Choosing an engine?

I tipped the canoe on my "9A" today and plan to order the finish kit on Monday.
Also engine time--- So now I start looking at all them Lycoming model numbers and yup they give me a headache.
Any one out there know the best model for 160 hp fixed pich prop with a fuel pump and dynafocal 1 mount?
A runout to rebuild or a clone are high on my list
Thanks
Frank

I don't know which engine is the best, but I installed an o-320-d2j in my plane, and the installation went well (so far...I haven't started it yet).

IMHO, look around and see what is out there. If you are trying to get an engine for a small amount of $$, you are probably not going to get the ideal engine (especially if the plane came off a Cessna, or other high-wing plane), but from what I have seen/heard, most engines can work.

When I started looking for engines, I called the major players (Aero Sport, Penn Yan, etc) and specifically with Bart at Aero Sport, I told him what I was building (9A), and he came up with an engine for me.

Hope this helps,

Ron
Rv-9A

Engines

Whatever you do, stay with a Lyc!! My buddy has an Eggy on his -7 that was signed off two months ago and has 1.5 hours on the tach!! ECU (computer) troubles and trouble codes that keep him grounded still! Plus excuses and ,more excuses when he should have had his 40 hours flown off by now. All this because he has his own strip and wanted to keep it there and burn mogas. The cost of the Eggenfellner ain't nuthin' to write home about either.
Pierre

pierre smith said:

Whatever you do, stay with a Lyc!! My buddy has an Eggy on his -7 that was signed off two months ago and has 1.5 hours on the tach!! ECU (computer) troubles and trouble codes that keep him grounded still! Plus excuses and ,more excuses when he should have had his 40 hours flown off by now. All this because he has his own strip and wanted to keep it there and burn mogas. The cost of the Eggenfellner ain't nuthin' to write home about either.
Pierre

Click to expand...

Pierre,
Has your friend posted his problems on the eggenfellner yahoo group?

They have quite a few guys there with lots of experience and may be able to help him. I follow the site regularly and have not noticed anyone with his kind of problems.

In fact, almost every single person flying with the egg sube seems to be extatically happy with their choice and they all talk about just turning the key and flying.
I think his problems may not be typical.

Have him check it out.

-Mike

Choosing an engine

In fact, almost every single person flying with the egg sube seems to be extatically happy with their choice and they all talk about just turning the key and flying.
I think his problems may not be typical.

Click to expand...

As an Eggenfellner customer, I was curious about the reported problem, so I checked with Jan. Here is what he wrote me:

We visited with Ralph yesterday to correct a loose / possible damaged, #2 plug wire. Engine now runs like a clock Here are the pictures.

To answer your question?

If you want a Lycoming, which I would highly recommend, here is a Lycoming ref document to pick the model that you might use, looking for a used engine.

Lycoming Certified Engine Guide

For a 160HP O-320 look at engines starting with a suffix D1A. For a 150HP O-320 look at suffix E1A. I believe both of these O-320?s have Dynafocal 1 and cont?l prop. Not saying these are preferred but just an example. In fact they are in rare airplanes. You will have better luck finding a D2A or E2A, which are fixed pitch versions of the D1A & E1A. The most common are likely out of cessna 172's, E2J, D2G. Not sure about the fuel pump pad? I think the new ones are based on D1A and D2A, 160HP c/s prop & fixed versions.

From there many variations can be found. The big thing to look for is if it has constant speed/fixed prop capability and Dynafocal 1. Avoid conical mount engines, as they just are not as desirable. I know I had one in my RV-4, which was not terrible but lousy compared to a Dynafocal. Even if you go fixed pitch consider picking an engine with the ability to use a hydraulic prop, great for future upgrade or resale. Other suffix mean small changes in magnetos, accessory pads (could be important if fuel pump pad is not there) and carb or carb location. There are also FI versions listed. Also look at the back of the document for what airplanes use what engines. Also the H2AD is a OK engine with some past history of eating cams, but it's an odd ball so avoid it.

Of course you can get a new Lycoming for about $18.5K fixed, $18.8K const spd, brand new.

http://www.mattituck.com/index.html

Using a new engine ($18.5K), stock parts and FWF kit from van?s accessories ($3.25K), a Sensenich metal prop ($2K), you could have a very nice new engine set up for under $23.8K. This will give you 10-20 years of trouble free flying. A Lycoming will be easy to install, no dual electric fuel boost pumps, radiators and redundant electrical systems as with auto engines.

Price the cost of "other" engine kit with a prop (Eggy). You are looking at about $37K; you will need the $8-$9K electric prop to get decent performance from a Subie. Not picking on the Eggy Subie, but price is not a bargain compared to a Lycoming. Plus you will have better resale with a Lyc. Why? People who buy used homebuilts are less likely going to tinker and will use A&P's, who know Lycs, have the tools and parts, available at 1000's of airports across the land.

You will find unless the Subie is turbocharged the performance will be better with the Lycoming. Also a Lycoming RV will weigh up to 100lbs less! Even a turbocharger will only give real benefit above 12,000 feet and the SUbie advantage will be small. If you fly at +12K feet sucking O2 all the time, a turbo is nice to have. Of course turbos are available for the Lycoming as well. The Subie weight, as much as 100lbs more compared to a Lyc powered RV, is a bummer for payload/fuel. Check it out. The installed finished weights are much higher.

As far as smoothness and reliability, well I hear the Eggy is smooth. I can tell you a well-built Lyc with a balanced prop is smooth enough. As far as reliability there are over 41,000 Lycoming O-320/O-360's in service all over the world. How many Eggy's are out there, actually flying? There are 500 Subaru engines registered of all models, including the pushrod version.

Cheers George

You seem to have already nailed down your minimum requirements, so look for any model that meets those!

Other than the '76' series engines (which current wisdom suggests avoiding unless......), most of the differences are in the details rather than applicability. Sure, a solid crank will avoid the recurrent inspections of the hollow ones, but that's a detail. Bendix vs. Slick mags, 3/8's vs 1/2" prop bolts (I assume in the -9 you don't plan on 'hanging on the prop very often) again are just details.

Most of the configurations out there were for a specific application, but for the most part the basic case/crank/accessory case configuration should work.

Pay attention to the guide George suggested, it's an excellent reference. A bit convoluted at times, but still excellent. Just use it as a referecnce every time you find a candidate engine to make sure there was nothing there that is a deal killer for you (like the H2AD!).

George,
Its obvious you like Lyc's, and that is fine, but I fail to understand why you think the ancient air cooled design is better technically than equivalent modern engineering, particularly with the POS antiqauated mechanical fuel injection system the "newer" hi-tech engines use. Please dont use the "because everyone uses them argument"- no technical merit there, only a historical bias. Chevrolet threw out mechanical fuel injection right after they tried it, and now carburation is rare, wonder why?

I dont have an engine-make bias formulated yet, but what I see technically in an air cooled engine are a lot of inherent disadvantages: high costs/low production, air cooling is prone to overheating under load, which requires loose part tolerences, which results in wear (poor longetivity) and tends to be vibration prone/rough running. The engines are limited to low rpm use because of its long stroke; the long stroke results in high internal mechanical stresses and heavy parts. The engines are not environmentally friendly; often limited to expensive 100 octane (often leaded) avgas to get any power without detonation with hot heads, and the lack of development/competition forces reliance on manual mixture controls, which results in excessive emissions and less than optimal mixture control (must balance overheating vs excessive fuel use) better done by computer control.

The only real pluses I see are the redundent systems in stock form (im not sure magnetos are a particularly good idea though) and easy c/s propeller installation, which the conversions can add if desired. The weight and fuel use issues are pretty much equal between the better designs, even when the reduction drives and cooling eqt is added. The automotive engines have big advantages in cost savings, engine and parts availability, engine durability, smoothness, high output without overheating due to water cooling, and they are constantly being improved because of the much higher production rates and inherent competition between manufacturers.

BTW, the eggy is a very good system, excessively expensive, but far from the only source; Subi's are probably the most common engine used these days in home-built planes and rotorcraft.

Many Lycoming parts are interchangable

If you get a good deal on an engine that isn't exaclty what you are looking for it might still work out.

I bought an O-290 (I know not the engine you want) that came out of a high wing Piper and thus it didn't have an engine driven fuel pump.

Some searching on the internet found a serviceable accessory case, cam gear, and "rod" to drive the fuel pump, total cost was under $250 plus the cost of some gaskets and the fuel pump. Make it less than $500.

For that I have an engine that will work great for my -9.

If you are even thinking of buying a rebuildable core, I suggest you buy the How to Rebuild a Lycoming Engine DVD from Mattituak. It doesn't cost much and will give you an idea of what is involved.

choosing an engine

Take it from someone who has taken a $25,000+ hit from an "alternative" engine company, DON'T DO IT. It was not Eggenfellner and he has a fine package. I am now firmly in the "put an airplane engine on an airplane" camp.

I now have a beautiful ECI IO360 on my almost completed 7. I'd have 300 hours on my plane if I'd just listened to those who tried to convince me to put an airplane engine on my plane.

The Lycs and clones may be old technology but they are technology that works. And, more importantly, they can be worked on virtually anywhere in world.

Darwin N. Barrie
P19

Yes the Subie will be heavier and likely slower than the Lyc. Also likely to be more expensive if you go with a FF vendor. I thought Lyc was advertising that they had produced their 30,000th piston engine just last year. For sure, not every one produced in the last 40 years in still in service.

There are likely more than 500 Subes flying as RAF has sold over 400 alone in their gyros over the last decade. Egg has apparently sold hundreds more with dozens now flying. Many more private ones have been flying for 5-10 years. The mechanicals are well proven with likely in excess of 150,000 flight hours.

If you fly a lot, the Sube might be a good value with its much lower overhaul costs and virtually nil maintenace. If you want the advantages of EFI and liquid cooling, no fuss controls, cruise at lower power settings and like something smoother than a Lyc, a Sube might be for you. If you want good speed, payload, lower initial cost or don't fly a lot, the Lyc is hard to beat on a $ per hour basis.

The Sube is just a viable alternative to the Lyc for many. Inferior in some ways, superior in others. There is no perfect engine out there that does everything best.

Subaru clarification

Our friend's problems with the RV-7/Subaru installation was much more involved that a "looose/broken plug wire". I became familiar with the situation around the first of the year, as I am building a Lycoming equipped RV-8 at the same airport. The first problem was the lack of an installation/wiring manual included with the engine shipment. Shortly before the DAR visit, several engine test runs were conducted and several rattle type noises/fuel pressure/computer code problems were encountered. The noises were attributed to the low RPM characteristics of the Reduction Unit. When questions concerning this noise were posed to Eggenfellner Aircraft, the noise was described as normal, but a $1300 upgrade was offered as a solution. The fuel pressure problem was posed to Eggenfellner Aircraft, the first solution was to increase the fuel pressure. two different ODBII scanners capable of reading a 2000 Subaru computer did not reveal the problem.Furthermore, the fuel pressure increase did not solve the problem. This problem was only resolved by Jan's visit to our friend's aircraft, last Sunday. The solution was to address a poorly functioning injector and a bad plug wire. The action solved the skipping/missing engine problem, but now the computer turns on the aux. fuel pump when the pressure falls below 29PSI. Call it one solved, another on on the rise. The third problem was with an "engine speed sensor" throwing off a code that caused the check engine light to illuminate and caused the engine to run rough. Jan was able to address this during his visit, last Sunday. Problem resolved.

The larger issues with any experimental aircraft product revolve around customer service. I will not go into the tit for tat, Chevy vs. Ford type of banter, but I submit the following: the gentleman that assisted our friend with the installation of the Subaru engine advised everyone involved of possible issues that may be encountered/require resolution-his predictions came to pass in droves; our friend with the RV-7 should not be required to resort to postings on a Yahoo to resolve his engine issues-while personel from Eggenfellner Aircraft visited our friend on two ocassions, it took a lot of effort to convince the company to address the issues in this manner; the gentleman that assisted our friend with the installation of the Subaru engine has expended extraordinay efforts to assist our friend and Eggenfellner Aircraft in resolving these and other issues with the installation and should be lauded for his efforts, not blamed for "missing a bad plug wire"; our friend should be hopefully rewarded for having the patience of Job during this shakedown process-I would not have the same attitude after expending that much money and time.

In closing, everyone involved with this installation has made an effort to resolve the problems. I believe Eggenfellner Aircraft can resolve these issues, but I would recommend that more timely response would have avioded much confusion. Subaru engines have been used for years in expirimental aviation and while I believe that Jan's premise in developing the Subaru for the RV is an excellent solution, I still have doubts about any automobile engine that was designed to cruise at around 2300 RPMs being used to turn 4000 plus RPMs to maintain cruise performance, not Subaru specifically. Additionally, I would not want to wait for the delay encountered with an electric CS prop. With over 300 units sold, Eggenfellner Aircraft has a proven install base and when expending $25000 to $30000 for a product, outstanding customer service in resolving issues should be a priority for the company. Understanding that not all solutions are yet documented and as with anything experimental, new problems can crop up everyday as Subaru changes the computer code on these engines monthly, it is my hope that others will not have to wait months for resolutions to nagging problems that keep them grounded.

If you need excellent assistance with a RV Project, contact Kaolin Aviation Services, in Sandersville, GA. I'll leave the engine choices up to each of you, but I do think that Yan's product is a viable alternative for builders to consider.

FWIW,
Robby Knox
RV-8, N82XS, 95% complete-95% Left to go

I ordered an O-320 from Penn Yan Aero and should be receiving it in a few weeks. 17.5K is getting me a 0-time rebuild, 160 hp with one mag and one Lightspeed ignition, F/P prop, skytech starter, etc. And no shipping charges. I am anxious to get it and will share observations good/bad as they occur to me. I am an A&P with very little recip experience so I wanted a turn key setup done by professionals.
Bruce Sacks
N659DB (res)

Gentleman, Gentleman, Gentleman,
First of all I have been in this homebuilding business since 1987, built a Wagaero cub (0-200A)from plans took 3 years flew it up until last April. sold it and was going to quit this airplane thing and that lasted a whole 2 weeks.
had a good part in building 2 Glastar's. In short I have been around and had my eye on the non aircraft engine folks for a while and in my opinion -- no thanks.
So I will shop for A Lycomming,I just wanted to get a few model numbers on my shopping list 160 hp, fuel pump, constant speed prop, carburetor,
seems simple enough but then I see 3/8" attaching bolts, this sump and that sump on and on--- Oh well it wil work out in the end.

Frank k--must have done to many nutplates today (baggage floor)

Cobra strikes again

cobra said:

George,
Its obvious you like Lyc's, and that is fine, but I fail to understand why you think the ancient air cooled design is better technically than equivalent modern engineering, particularly with the POS antiquated mechanical fuel injection system the "newer" hi-tech engines use.

Click to expand...

No I don't think a Lyc is technically equivalent, it is technically superior for aircraft uses, at least if you look at lower weight, less real cost, ease of construction, performance. Other than that the auto engine, Chevy V8/V6, Subie, Mazda are great. I don?t think a magneto, carb or mechanical FI is technically better, but more reliable and independent of the electrical system. As far as making a better failsafe electrical system with all the required electrical dependency, I say great, do it.

However until you autoengine lovers get the weight down, performance up, fuel burn less, noise down, hydraulic prop control, direct drive (no reduction unit), installation as easy as Lycoming including a custom cowl, less cooling drag (with radiators stuffed in the cowl) and at price less than a cost of a new Lycoming using stock Van's components, than yes, a Lyc is better, practically and technically. What else can I say, You want to cary more payload a Lyc is still best. You want to race? Bring it on Cobra

?I LIKE LYC? Mo power to ya Cobra

All the best George

Core required?

bsacks05 said:

I ordered an O-320 from Penn Yan Aero and should be receiving it in a few weeks. 17.5K is getting me a 0-time rebuild, 160 hp with one mag and one Lightspeed ignition, F/P prop, skytech starter, etc. And no shipping charges. I am anxious to get it and will share observations good/bad as they occur to me. I am an A&P with very little recip experience so I wanted a turn key setup done by professionals.
Bruce Sacks
N659DB (res)

Click to expand...

Bruce: just curious, did you have to turn in a core from an O-320 to get that price? If so, how much was the core worth?

Originally Posted by bsacks05
I ordered an O-320 from Penn Yan Aero and should be receiving it in a few weeks. 17.5K is getting me a 0-time rebuild, 160 hp with one mag and one Lightspeed ignition, F/P prop, skytech starter, etc. And no shipping charges. I am anxious to get it and will share observations good/bad as they occur to me. I am an A&P with very little recip experience so I wanted a turn key setup done by professionals.
Bruce Sacks
N659DB (res)

Click to expand...

If you were able to get all you listed for 17.5K you got a great price compared to what I was able to get quoted to me. My calls to Penn Yann yielded a price around 19K for an 0-320 with slick mags, wiring harness, F/P prop and starter. That price did not include alternator or vacuum pump.

Original posted by gmcjetpilot No I don't think a Lyc is technically equivalent, it is technically superior for aircraft uses, at least if you look at lower weight, less real cost, ease of construction, performance.

Click to expand...

George, I agree with you concerning the fact that at present the Lycoming engines are going to be my best economical, performance, resale value leader of choice when it comes to engine choices to put in my RV. What I am discovering is that no matter how I feel about wanting to put something different in my plane to make it go, the reality is I cannot beat the Lycoming engine(s) for providing me with economy, performance, ease of construction. However, I cannot agree that this makes these engines "technologically superior". Superior, yes because of the lower weight, less real cost, ease of construction, performance but not technologically superior. Technology has nothing to do with making these engines "superior". Economies of scale are what is tiping the balance into their favor. The fact that there have been tons of them made, that there are a kazilion mechanics out there that know how to work on them or that the average airplane buyer wants to see them in an airplane are the real reasons why they are "superior". It all boils down to money not technology. Which is exactly why I will end up with a Lycoming something or other in my RV rather than the very impressive Eggenfelner Subaru package. I can afford the Lycoming, I cannot afford the Egg Subie.

RVBYSDI
Steve

Weight comparisons

gmcjetpilot said:

You will find unless the Subie is turbocharged the performance will be better with the Lycoming. Also a Lycoming RV will weigh up to 100lbs less! Even a turbocharger will only give real benefit above 12,000 feet and the SUbie advantage will be small. If you fly at +12K feet sucking O2 all the time, a turbo is nice to have. Of course turbos are available for the Lycoming as well. The Subie weight, as much as 100lbs more compared to a Lyc powered RV, is a bummer for payload/fuel. Check it out. The installed finished weights are much higher. Cheers George

Click to expand...

The Eggenfellner web site shows the following weights:

2004 and 2005 2.5 STI engines are 345 without supercharger ready to fly with mount etc.

2004 and 2005 2.5 STI engines are 365 with the supercharger and 200 HP.

2004 3.0 H-6 engines are 430 ready to fly - 190 HP.

2005 3.0 H-6 engines are 445 ready to fly - 200 HP - variable valve timing

IO-360 firewall package - 180 HP - that came off the RV-6A was 415 lb

Am I missing something? John

gmc...,
Your words: "However until you autoengine lovers get the weight down, performance up, fuel burn less, noise down, hydraulic prop control, direct drive (no reduction unit), installation as easy as Lycoming including a custom cowl, less cooling drag (with radiators stuffed in the cowl) and at price less than a cost of a new Lycoming using stock Van's components, than yes, a Lyc is better,"

As an engineer, Ive learned to identify relevent system specifications, then pick from the applications that at least meet them- Not the other way around. The selection often falls to secondry criteria (smoothness, durability, parts availability, mainenance support, etc) when the other factors are similiar. You've provided unsupported annecdotal arguments to support your bias. I dont, I like real performance numbers to compare. Here are some of those numbers for you to chew on.

Rotary 13B wet weight, installed and running: 325 lbs. with oil, water, mount,
reduction unit, exhaust, and engine control system.
Output w/fuel injection: around 180 HP naturally aspirated, 225+ if turbocharged (the new Renesis 2-rotor engine update produces between 230-250 HP naturally aspirated at slightly less weight and better economy). The 3-rotor 20B produces around 300HP. All are electronic fuel injected, automatically controls fuel and spark at any altitude.
Cost: abt $4000 with full overhaul and aftermarket engine controls (overhaul kit is cheap, abt $400). Renesis engine will be about twice that, at least for a short while until they become more common.
Reliabiity: probably north of 2000 hrs to "rebuild" (no measurable wear at 1500 hrs. and counting, because Roraries have very few moving parts and no reciprocating stresses to contain).
Fuel burn: 8 gph at 202mph, 6.0 gph at 172 mph with fixed prop.
Cooling drag: come on, get real. Lets talk about reduced performance from overheating if you want). The cowls are generally the same part.
Reduction unit: what is the beef, the reduction units are practically industructable and included in the total engine weight and cost comparisons.
Noise: similiar, subjective, and controllable in any application. Rotaaries have a bit of a whine, like a turbine.

The numbers suggest the auto conversion here is comparable in weight, efficiency, noise output, and output unless you compare the newer engines which favor the Mazda's. Cost strongly favors the auto engines, due to much higher prduction rates and availability. Parts (mounts, engine control, etc) are now available for easy installation, included in cost comparison.

Now its your turn to supply the Lyc numbers. Lets put all the cards on the table. If you are really sure of yourself, lets compare the IO-540 and the Renesis (the best of the breeds). This is fun, bring it on...

You must have been shocked that the two RV-8 Rotaries, compared by Vans to a 180 hp and 200 hp rv7 and 7a were slightly slower for alot more fuel burn and noise.

Guess those comparisons must not have been real numbers.

I saw a rotary blow its lunch at a racetrack...spectacular.

On the other hand When I dropped off parts at the local aircraft engine shop I saw a crank that broke clean through at the number 1 journal fillet from an unrepaired prop strike.

The engine got rough, but continued to run for the 35 minutes it took for this plane to get to the ground.

Saw a lycoming run 3 hours with no electricity...unlike the sube that went down, killing a guy (the electric pumps these engine controls take are high drain. I guess that the more modern HP electric pump must be more advanced than the "outdated" mechnical pump on the "outdated" carbed or injected Lycoming....unless of course you want to live through an alternator failure. These are the same electric pumps necessary for the rotaries, they must be on constantly, they are not mere boost pumps, and when they died the engine also dies, instantly.

As an engineer, how much performance would you need to overcome the inability to withstand a common system failure like a charging failure?

Airplanes cannot pull over, they can only come down. When was the last time you heard of a vapor locked lycoming? How many different fuel systems have been tried on the auto conversion? With how many totalled aircraft from Vapor lock.

As an engineer, why do we need the complexity, and parts count of a system designed for a dynamic RPM installation, where throttle transistion is critical, for an airplane application where the RPM is nearly static, and throttle transition is not critical?

As an engineer, why is it more efficient to transfer heat from metal to water to metal to air, rather than simply from metal to air?

As an engineer how does the addition of an entirely new system (cooling) create efficiency or reduce the probability of failure?

Finally, if this can be done for $4K to buy a core and a fuel management system, why is Mistral investing hundreds of millions of dollars? I am sure they could have worked a deal with Mazda to buy cores. Heck most junkyards have enough cores for years to come? Perhaps their engineers are just not smart enough to figure it out.

Electrically dependent engines

Saw a lycoming run 3 hours with no electricity...unlike the sube that went down, killing a guy (the electric pumps these engine controls take are high drain.

Click to expand...

Do you have more information about this claim? I can't find anything in the NTSB files, but perhaps it didn't happen in the US.

It is true that most (all?) auto conversions are electrically dependent, but that does not seem to be too difficult to handle. The glider guys give us a hard time because we fly gasoline dependent engines. Not really much difference. Just make sure you have enough gasoline and electrons, and go flying. The cool part is due to some magic we can generate our own electrons along the way.

rv8ch said:

The glider guys give us a hard time because we fly gasoline dependent engines. Not really much difference.

Click to expand...

I hope not to sound trollish, but when was the last time anyone saw a glider get off the ground without a gasoline dependent engine?

Just thinkin'

Winch launch?

I hope not to sound trollish, but when was the last time anyone saw a glider get off the ground without a gasoline dependent engine?

Click to expand...

Electric winch launchs don't use much gasoline...

cobra said:

gmc...,

Rotary 13B wet weight, installed and running: 325 lbs. with oil, water, mount,
reduction unit, exhaust, and engine control system.
Output w/fuel injection: around 180 HP naturally aspirated, 225+ if turbocharged (the new Renesis 2-rotor engine update produces between 230-250 HP naturally aspirated at slightly less weight and better economy). The 3-rotor 20B produces around 300HP. All are electronic fuel injected, automatically controls fuel and spark at any altitude.
Cost: abt $4000 with full overhaul and aftermarket engine controls (overhaul kit is cheap, abt $400). Renesis engine will be about twice that, at least for a short while until they become more common.
Reliabiity: probably north of 2000 hrs to "rebuild" (no measurable wear at 1500 hrs. and counting, because Roraries have very few moving parts and no reciprocating stresses to contain).
Fuel burn: 8 gph at 202mph, 6.0 gph at 172 mph with fixed prop.
Cooling drag: come on, get real. Lets talk about reduced performance from overheating if you want). The cowls are generally the same part.
Reduction unit: what is the beef, the reduction units are practically industructable and included in the total engine weight and cost comparisons.
Noise: similiar, subjective, and controllable in any application. Rotaaries have a bit of a whine, like a turbine.

The numbers suggest the auto conversion here is comparable in weight, efficiency, noise output, and output unless you compare the newer engines which favor the Mazda's. Cost strongly favors the auto engines, due to much higher prduction rates and availability. Parts (mounts, engine control, etc) are now available for easy installation, included in cost comparison.

Now its your turn to supply the Lyc numbers. Lets put all the cards on the table. If you are really sure of yourself, lets compare the IO-540 and the Renesis (the best of the breeds). This is fun, bring it on...

Click to expand...

Hang on a minute here. Lets look at some real figures.

Weight: This is actually a hard one to find. There are a lot of different figures quoted for engine weights. I would suspect that the weight is similar with the rotary having a slight edge.
Cost: $4000!!! Are you kidding. There is no way you could put a rotary in an RV for $4000. According to the powersport engines site the rotary engine is $22,500us plus another $5000 for the installation kit. The prop reduction unit is $6,500 alone!!. I can get a new Lyc clone for less than that. In the latest RVator Van states that the cost of the rotary engine installs tested was comparable to a Lyc 0-360. Also $400 for an overhaul kit. Would you honestly fly an engine for 2000 hours, pull it down, throw a $400 overhaul kit at it and go fly for another 2000? There is a reason why overhauling a lyc cost so much.
Reliability: I would suggest to you that the 0-320 / 0-360 range of engines are amoung the most reliable piston engines getting around. There are not enough rotaries getting around in aircraft to say they are more reliable than a lycoming engine. I have experience with rotary engines, albeit in cars. Needless to say the ones I have seen in cars make me happy I'm getting a lycoming. Lycoming have made a LOT of aircraft engines. I think its pretty safe to say they know what they are doing.
Fuel burn: I have driven a rotary car for quite some time. They are fuel guzzliers. Especially at the 6000rpm they run at in these installs. Dont believe me?
From the latest RVator. I'm sure most of you would have read this but anyway.
Their test showed the rotaries consistantly burnt more fuel than the lyc's for the same flight.
an example
Flight 3 (cruise 2500 prop rpm WOT over a specified distance)
rotary 1 burnt 29.3 liters
rotary 2 burnt 27.2 liters
IOF-360 burnt 19.4 liters 180hp
IO-360 burnt 20.9 liters 200hp
They did two other flights with similar results.
Speed: But the rotaries are faster I hear you say. Lets face it for the same HP all things being equal the plane is going to go the same speed regardless of what engine it has. We know that all things are not equal. The main difference being the rotaries would have a drag advantage due to the lower frontal area.
The RVator results had the 180hp lyc powered plane and one of the rotaries being within 1 knot of each other. The other rotary was 3 knots faster while the 200hp lyc was 10 knots slower (It is the only A model on test). So a slight advantage to the rotary but not much.
Noise: There is no way around it. Rotaries are loud. In the RVator test the rotaries were about 10db louder than the 180hp lyc. 10db is a lot. a 3db increase represents double the volume. They even stated in the test that while they were testing the rotaries the airport manager came out to see what was making all the noise.

I am not saying that rotaries are bad and everyone should have a lycoming but in your post you stated
"You've provided unsupported annecdotal arguments to support your bias. I dont, I like real performance numbers to compare. Here are some of those numbers for you to chew on."
The numbers you stated are just plain wrong. If we are going to compare the two engine type we should compare some real numbers obtained in a proper test rather than guesses.

"Just make sure you have enough gasoline and electrons, and go flying. The cool part is due to some magic we can generate our own electrons along the way."


My point is that when the alternator fails, those fuel pumps are a high amp draw and will extinguish the battery very quickly. Then you are coming down.

These are short span, high wing loaded planes. Talked to a local guy who did a dead stick landing in an RV-8. He has thousand of hours as a millitary pilot and test pilot. He said it was downright scary how fast you have to descend in a C/S prop RV that looses power.

So, just pointing out that the self sufficient lycoming which can create spark, and pump fuel indefinitely, without electricity, is a saferdesign.

Penn Yan

No core turn in required. The base price is 14k then you select options from there such as hp, carb, ignition, starter. I don't have my order form in front of me and you need to get them to send you the price sheet in order to get a realistic idea of the total cost. Mine came out to 17.5k and if anyone is still interested in exactly what I ordered contact me. They build and test your engine, then send you the run data with it. Build time was quoted at 6 weeks.
Bruce

Alternator failure

Jconard said:

My point is that when the alternator fails, those fuel pumps are a high amp draw and will extinguish the battery very quickly. Then you are coming down. ...

Click to expand...

This is true, which is why you need to understand your loads, make sure you know when the alternator fails, and make sure you have enough spare battery capacity to get you to the nearest airfield.

On my RV8 I estimate my loads will be less than 15 amps if the alternator fails, and I have two 17AH batteries. That means I need to get on the ground within about two hours if I see that the alternater has failed.

SeveraL replies:
JConArd- You made several excellent observations, particularly concerning complexity vs reliability. There are times when additional complexity is needed to solve a specific problem. Air cooling simply has heat transfer limits in high performance engines. Even motorcycles have converted to water cooling these days. Heat destroys engines thru two pathways- it degrades the lubricating capacity of oils (high engine wear), and more importantly, it leads directly to detonation. Detonation is a killer to heads, head gaskets, pistons, valves and bearings. Because air cooling leads to higher engine temperature, parts have to be designed with a lot of clearance to allow metal expansion/contraction. Excessive tolerences lead to high wear, vibration, and metal fatigue.

The rotary engine has far fewer moving parts than just about any other engine that I can think of- only the triangular rotors rotate in the engine itself, no valve train, and they stay in continual one-direction motion, like a turbine. Reciprocting engines are hard on bearings, constant pounding involved, and the stresses are much worse with long stroke, big bore, air-cooled engines historically used in aircraft. That is why their TBO's are so important to monitor. Each piston has to accelerate to maximum velocity at 90 degrees, decelerate to stop at 180, accelerate to peak velocity at 270, and decelerate to a complete stop again on EVERY engine rotation. Each change of direction puts a pounding stress on crank and pin bearings. Long strokes add excessive angular stresses (from the long crankshaft throw) to the mix, along with increased piston travel distances, as compared to normal short stroke automotive designs.

Grant Ed:
I have not seen Vans article. I like head-to-head comparisons, but only if the test setup is unbiased. Keep several things in mind-1) 2 planes is not a particularly good representation of all the possible setups in new expiremental designs, and 2) speed is not a reliable comparison comparison between different aircraft with different engines- there are too many variables involved that have little to do with the engines themselves. Regarding the rotaries in the test- what generation engine was used, what fuel system, what exhaust system, etc, are you basing your assumptions on.

Tracy Crook is probably the most experienced engineer with Rotary conversions. Go to his website for detailed cost and performance data http://www.rotaryaviation.com/faq.html I referred to. Everything he does is measured and compared. For example, his planetary redrives all cost between $2350-3000 delivered. His digital engine control system, with redundent ignition system, costs $875.

A rotary has few moving parts and no reciprocating parts to wear or break down, therefore the overhaul is easy and involves only a few metal apex seals and some O-rings. You can purchase a low-mileage, 2-rotor 13B Japanese engine for 800-1500, depending on model from any of a number of importers- most of their parts interchange. The twin turbo version from the RX-7 is more, around 4000. The cooling system parts are available from junkyards, if desired, to keep costs down.

High rpm is not a issue with a rotary, again like a turbine. They can run continually at 6000 rpm without any issues at all, and much higher if desired (as in the race engines to 12,000 with lowered durability).

As for the noise issue, it really depends on the mufflers and pipes used, like any other motor- I have no idea what the planes in Vans article used. Straight pipes are a bad idea, in either application. The best noise reducer is probably a turbocharger

Look You-allll I was just kid-in

Look I love airplanes, anything mechanical and if it makes noise, burns fuel and especially fly?s I love it.

My "technically superior" comment was tongue in cheek because of the way the question was posed. I also have an engineering degree BTW so I won?t hold that against you.

5 things I don't like about auto engines:
WEIGHT:

Really as far as weight all you have to do is look at the scales: From my list and Dan's list: http://www.rvproject.com/wab/

(2) Subie's: empty weights (lbs)
(2) Mazda: empty weight (lbs)(120) RVs and their average empty weight?s with fixed or c/s props, models (RV-4,6,6A,7,7A,8,8A,9A)Let the numbers speak. Except for the one Mazda all the auto engines are near 1200 lbs! That is heavy. Mazda seems to have an edge on the Subie but was still 1100 lbs with a fixed prop. That is 30-75 lbs heaver than comparable RVs with O-320/O-360/fixed pitch props. Not bad but could be better. Of course who knows about paint, equipment, lights etc. Regardless weight is not an issue. Auto engines weigh more, no surprise.

For the record an (I)O-320/(I)O-360 weights vary from 240-280 lbs. The Lyc IO-360 (angle valve, counter weight crank, 200HP) is a heavy engine at 320-330 lbs , not 400 lbs or whatever. An (I)O-540 does weigh 360-375 lbs, and can put out 250-300hp continuously. Again real HP at the prop, not auto engine numbers at 8000 RPM. Dyno of an auto engine should be w/ PSRU and components used in airplane. Installed weight: remember your auto engine needs the PSRU, radiators, coolant, extra fuel pumps and batteries.

HEAT EXCHANGERS: When Van designs in integral cooling tunnels in the fuselage belly or a better way (less drag) to locate radiators is found auto engine installations will suffer more drag. Just throwing radiators in under the cowl with no baffles or diffusers is not ideal. To be fair the air-cooled engines have over 75 years or research funded by the government to reduce and optimize cooling drag in air-cooled aircraft engines. Last work from NASA was in the 70?s from funded work by the U of Mississippi on reduction of cooling drag in horizontally opposed air-cooled engines. The result is the round cowl inlets, pressure plenum benefit quantified and data on cowl exit design factors. There is info, which is relevant to radiators for water cooling in this report. This is where more work is needed for water cooled engines, but the airframes are designed for air-cooled engines. The work done on the P-51 is available from NACA (NASA's predecessor) may be of use. My point is the radiator installations are aerodynamically ugly.

PERFORMANCE: Well this is hard to prove but I?ll go the races. There have been a few fast Subies and Rotary engines, but by in large the Lycomings are going much fastest in the races. Tracy Crooks RV-4 has been getting faster of the years and he came in third in the general 160HP class at the Sun 100 race 2004. If he raced in the 180hp RV class he would have finished 6th. This is good, nice job, but remember Tracy has been screwing with this for years. Who knows how many RPMs he was turning?

http://www.aircraftspruce.com/sunfunraceresults1.php

Also the heads-up comparison Van did between two beautiful Powersport Rotary engine RVs and a 180hp RV showed they were right up there in speed, however the fuel burn of the rotary RV?s was large (see the last RVator). The powersport engines are highly modified 13B Mazda from Everett Hatches work. They also had nice custom cowls (James aircraft). The claim of 215hp for these highly modified Mazda engines only fly as fast as the 180hp RV. Is it cooling drag? Is it the extra weight? Don't get me wrong, but they burned huge fuel over the Lycoming for equiv speed. At least they performed well. They weighed about 70lbs more than the Lyc 180hp Lyc RV.

http://www.powersportaviation.com/


Also a rotary has 3 rotating parts and is nothing like a turbine, more like a two stroke engine. I know I fly turbines. The noise my be solved at cost of weight and drag but the design of the engine will always have a bit of fuel burn disadvantage. Also a side note and one thing I don't like is adding oil to the fuel. A minor issue but a hassle, about 3/4th qt of oil every fill-up. My Lyc takes a qt every 4-5 fill-ups (16 hours).

The real proof is in actual flight test against similar RV?s with Lycs. Auto engine performance is making head way. If the cooling drag and weight issues are addressed while adding reliable power you are on your way to a true alternative, which is better. However that is easier said than done and no guarantee it can be done. In the mean time Lycomings are getting roller cams, electronic ignition, composite oil pans, more manufactures AND getting cheeper (O-360 new, all accessories $18,000). OH NO


HYDRALIC PROP CONTROL: PSRUs do not have hydraulic prop control**. I don?t hate electric props or MT, but they just are not as good as hydraulic control. It is a compromise not a preferred design. Also MT props cost too much. Electric MT props are "9 Large". I just can?t imagine having to ship my prop to and from Germany when there are lots of companies in the US that make all kinds of metal and composite props, 2 and 3 blades. (Like the fastest prop, a 2-bladed blended Hartzell for $5.5K that can be worked on by every prop shop.)

The PSRU already weighs enough. To add the gov drive would add weight, cost and complexity. Needless to say the Lycoming was designed from the drawing board to use a hydraulic prop and it's weight includes this capability. No PSRU needed with direct drive.

**(http://www.mistral-engines.com/ has a PSRU with prop control, the story is they will sell them for $6.5K? There goes some of the cost advantage of a homegrown Mazda installation.)

Subie and the Mazda are hurt by fixed pitch props may be more than a Lycoming because they need RPM to make power. Remember an O-360 is almost (6) liters. How many liters is a Subie? (3) liter. No wonder there is less vibrations the pistons are small. Lycoming pistons are 5? in diameter. Of course the higher RPM?s auto engines need means a PSRU. A necessarily evil I guess, but the direct drive Lyc is elegant in it's simplicity. By the way gear drives are not new. Lycoming and Continental have had geared engines for decades.


SYSTEM COMPLEXITY:More batteries, more alternators, more pumps, more pipes, more heat exchanges and complete dependance on electrical power and electronics. Yes they are work arounds but it's not KISS.


In closing I love all planes and engines, but I don?t have the time to engineer and play with an installation of my own design. Of the off the shelf Subie kits, nice but not optimized and cost too much, way too much. The off the shelf Rotary (powersport) is out of production and was a little spendy but very nice. Hope powersport comes back. Do it yourself Rotary? Nice, get a PSRU with hydraulic prop control, reduce weight (titanium exhaust pipes) and Van offers an option to install radiators in firewall or belly. Cost? Performance better than a Lycoming? There will be very little profit in FWF kits in a small market and cost will be high, and they will be competing against Lycoming, like it or not. The best auto engine installations and designs are going to be custom and limited to individual efforts of a few talented folks for a time to come.

My criticism is constructive and some what factual and correct I hope. No offense intended. The Lycoming is not manna from heaven, but it is not bad if you respect it's limitations: Keep CHT below 400F, oil temp 190-210F, use proper leaning technique, don't abuse it with fast throttle changes and shock cooling, fly often and change the oil.

The alleged benefit of auto engines in maintenance and overhaul is overstated. Your going to have to wait a long time for this to pay-off. A Lycoming can go 10-15-20 years without overhaul if limits are observed. I should know I have gone to past TBO twice with no problems. You will have to change the oil less in a Subie but that is chump change. No one has flown a large turbo Subie for 2000 hours or 20 years, so all the maintenance talk is really a guess. How long is that PSRU going to last. If your engine is fine but the wind maker takes a dump, you are screwed.

The auto engines have less delicate temp issues and less "mass inertia" of parts. (Yes I know "rotary engines go round", my family owned a RX2 and RX3 in the 70's.) Water cooling is great, but in a plane it's a double edge sword. I think a Lycoming with water cooling would be great.Cool Jugs! They are cool but they cost more and add weight; Also, you than have to deal with the radiator installation design issues. Air cooled sucks (or is it blows) but it is well established and works.

Cheers George MSME, ATP, CFI

() Corrected thanks MC

6 liters

gmcjetpilot said:

Remember an O-360 is almost 4 liters. How many liters is a Subie? 2.5 liter.

Click to expand...

If my conversion program is correct, the 360 (360 cubic inches) is 5.899343 liters, or almost 6 liters. The "big" Subaru H6 is 3.0 liters.

SeveraL replies:
JConArd- You made several excellent observations, particularly concerning complexity vs reliability.

"There are times when additional complexity is needed to solve a specific problem. Air cooling simply has heat transfer limits in high performance engines. "

Not true. First, it is only air that transfers heat from your radiator. Second the rate of thermal transfer to air is proportional to the difference in temperature...more heat transfers as the difference between the metal and air temps go up...but the rate is the same for air to metal whether it is in the head or radiator.



"Even motorcycles have converted to water cooling these days."

RESPONSE: Not relevant....water cooling in cars and motorcycles was necessitated by two things, packaging and wide speed variation. It is much easier to duct fan blown air through a radiator, than it is to duct it over an engine, an important consideration for a vehicle that may sit and idle. It also allows the heat transfer to be moved to an area where air can enter and exit more efficiently. This was key to the motorcycles. If you remember correctly Dirt bikes were some of the first to use water cooling...because short of huge fins they could not keep the engines clean enough to transfer the huge heat/little airflow generated when you sit and spin your wheels in a mud bog. Later as fully faired sportbikes became popular, ducting was critical and the packaging needs of the engine made it impossible to give the engine the necessary cooling fin surface.

As an interesting side note, the GSX-R was successful for years (From 85-97 I believe) as an air and oil cooled sportbike. I still love them today, they won because they were reliable as a hammer, and were very, very light. Only when specific outputs got to a point roughly double that used in aircraft did they need to go to water cooling.

None of this applies to aircraft where the speed is always high when output is high, and where there is good reason to duct air over the engine rather than over some other device. There are also important benefits to simplicity and light weight in an aircraft.


"Heat destroys engines thru two pathways- it degrades the lubricating capacity of oils (high engine wear), and more importantly, it leads directly to detonation. Detonation is a killer to heads, head gaskets, pistons, valves and bearings. Because air cooling leads to higher engine temperature, parts have to be designed with a lot of clearance to allow metal expansion/contraction. Excessive tolerences lead to high wear, vibration, and metal fatigue. "

RESPONSE: The same amount of heat will be created to make horsepower, it must be transfered to the air to get rid of it. Water is less efficient than metal to air...that is it accepts less heat, as a function of wetted surface than does air, so you will either have similar temperatures, or you will need greater metal to water to air transfer areas. Most water cooled engines do not measure CHT directly, they measure the water temp in the water jacket of the head casting. In my experience an "under the sparkplug" CHT sensor will read much higher in a watercooled engine than in an aircooled engine.

BY THE WAY THERE ARE NO HEAD GASKETS FOR LYCOMINGS.

Finally, the tolerances you discuss are made necessary by running aluminum pistons in a cast iron bore. As I am sure you remember aluminum expands at roughly double the rate of iron. These tolerances are not high enough to lower fuel efficiency, or create excessive oil consumption, both of which are comparable to and usually much better than the car engines.

There is huge stress on the eccentric block and cam in a rotary. They can and will blow, I have seen it, at a race track, and it is truly spectacular when they do.

I think the wankel is cool. It is an awesome powerplant in a formula car. But you can hurt them simply by reving them with no load, or too much reverse load (over agressive down shift), they are not completely bullet proof.

Light, simple, powerful, and efficient....tell me; what is the definition of elegant?

Both replies excellent, well thought out, informative. I got a lot out of each.

It is my understanding that at top (racing) speeds, that small aerodynamic differences and weight differences between planes are more relevent than power differences. Am I wrong?

For my own education, how much of a loss of performance/economy is lost or gained between a fixed and c/s propeller? Tracy's fixed-prop RV4 has been competetive with the best of the pack, and with the new higher-output Renesis engine (90? more HP, better economy, lighter) and appropriate propeller, could prove somewhat faster.


For sufficient air cooling it seems a lot of additional air-to-metal contact area is needed as power level is increased, which is physically restricted by weight and space considerations. With water cooling, you can easily incease the radiator thickness, increase water pressure/flow rates, add additional radiators, or possibly improve the heat-transfer medium if needed.

Id like to add one more thought- the decision of which engine is "BEST" is subjective and depends entirely on which criteria the judge uses to compare specifications. I think ALL we can really say in a forum like this is that a specific engine meets the criteria, that it is adequate. The rest of the discussion involves opinions and personal biases.

It seems to me that the systems we have discussed so far are adequate, and seem work well within the aircraft design performance envelope. The eventual individual choice boils down to personally-chosen intangibles, things like: cost, ease of installation, engine running characteristics, fuel economy, maintenance requirements, etc).

Comments about oil consumption on a Lyc being lower than most cars????? Really. I added the first quart of oil to my new BMW at 400 hours. Is there any Lyc that has ever burned less oil than that. Come on!

Head temps lower on a Lyc than a liquid cooled engine at high power???? This is physically impossible and illogical. Porsche converted all their endurance racing air cooled engines to water cooled heads a long time ago. At high power levels, air cooled engines cannot reject the heat fast enough without very huge fins like the sawed fins seen on the big Pratts and Wrights. At Reno, these even require ADI and Spray bar water to keep things from melting.

Exhaust seats and valves suffer the highest heat flux followed by chambers and pistons on air cooled engines.

You see any air cooled racing engines in any upper form of auto racing? Want to know why? Physics.

"For sufficient air cooling it seems a lot of additional air-to-metal contact area is needed as power level is increased, which is physically restricted by weight and space considerations. With water cooling, you can easily incease the radiator thickness, increase water pressure/flow rates, add additional radiators, or possibly improve the heat-transfer medium if needed."

What you are missing: 1) The transfer from the engine to the water is actually less efficient than to air, both transfering heat into the coolant and then into the metal of the rad. 2)The rad must have just as much surface area as the cylinders would, and because of lost efficiency, more. The same amount of heat transfered requires the same amount of time/space.


"Comments about oil consumption on a Lyc being lower than most cars????? Really. I added the first quart of oil to my new BMW at 400 hours. Is there any Lyc that has ever burned less oil than that. Come on!"

ANSWER: Run your BMW at 5500 RPM (70%) for 15 hours straight and it will use more than the one court my Citabria burned per hour.

"Head temps lower on a Lyc than a liquid cooled engine at high power???? This is physically impossible and illogical. Porsche converted all their endurance racing air cooled engines to water cooled heads a long time ago. At high power levels, air cooled engines cannot reject the heat fast enough without very huge fins like the sawed fins seen on the big Pratts and Wrights. At Reno, these even require ADI and Spray bar water to keep things from melting."

ANSWER: 1) In all cases it is metal to air heat transfer in the end, the surface area required there is the same, the ability to reject heat is the same. The aluminum fins of a radiator have the same transfer coeficient as an aluminum cylinder head.

2) The internal heat content is the same, power is a function of heat. Since the output is high for lower fuel burn it actually means that less raw heat is created in a Lycoming. There is a constant amount of heat created per unit of gasoline that is burned. So it is not physically impossible or illogical.

3) REREAD, I said that the temps measure by most are two different temps air coolde head temps are read in the casting or at the sparkpluc, water cooled are read in the water jacke or the outer casting. My experience with both types of racing engines is that if the head temp is taken at the sparkplug, water cooled heads always run a little hotter.

4) A combination of factors combined for Porsche, but many packaging and aerodynamic demands made it easier for them to maintain drag/downforce ratios, and cool their engines by repackaging heat into radiators placed strategically around the car. Inapplicable to an airplane because drawing in pressure air at the front and ducting it out the bottom, works very well aerodynamically and is a simple system.

As a point of reference, I just re-engined my 77 Westfalia. Its air cooled 2.0ltr 100hp engine went 104,000 miles before rebuild and ran great, runs even better now...with the appropriate packaging, air cooling is an excellent method.

Oil burn/use

rv6ejguy said:

Comments about oil consumption on a Lyc being lower than most cars????? Really. I added the first quart of oil to my new BMW at 400 hours. Is there any Lyc that has ever burned less oil than that. Come on!

Click to expand...

I don't think any one said that? You are right cyl/piston clearance is much better with water cooled engines and do burn less oil. If you were referring to my comment about oil use in rotary engines, which require you to add two stroke oil to the gas directly or in an injector. From what I was told every fill up (L&R wing tanks) you add 3/4 qt of oil. That is more than a Lycoming. The Subie? I guess nothing, like most new car's.

Our Sube uses 1 liter of oil in 40 hours which is where we change the oil at the present time. About the same as a REALLY good lyc. Most Lycs I've flown use a liter in 5-10 hours. Spends most of its life at 4600-4800 rpm under boost.

A coolant rad is capable of rejecting far more heat than a few fins on an air cooled engine of the same volume despite the heat transfer coefficient of the aluminum parts being the same. You're missing the part about the exposed surface area of a folded and louvered fin and their proximity to the coolant tube.

Air cooled engines have the advantage of higher Delta T of course. This is balanced somewaht by relatively poor heat transfer to the air because of the distance from the hot parts to the fins. Especially critical in the exhaust port area. This is the main limitation to producing high power levels on air cooled engines. Wright and Pratt ran into the same problems 60 years ago.

Liquid cooled engines have water jackets surrounding the exhaust ports and spark plug sockets in most cases. I don't see over 270F on the aluminum boss under the plug on the Sube. How can you have less than this on a Lyc with a CHT of 400F?