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  #1  
Old 02-23-2020, 06:52 AM
N546RV's Avatar
N546RV N546RV is offline
 
Join Date: Aug 2010
Location: Houston, TX
Posts: 910
Default IO-390 options?

OK, so I'm looking into options for a ~200-horse engine application for my RV-8. I'd been planning on a Titan IO-370, but last week I learned that the Whirl Wind no longer "supports" their props with the 370/375 engines. Still need to try and run down that reasoning, but in the meantime, I'm doing thought experiments.

The most obvious alternative is an angle-valve 360. I can get one from Van's for only a couple grand more than the Titan 370 I spec'd out last year.

BUT...

When looking at the engine list on the Van's site, it's hard to keep my internal Emperor Palpatine from moving his eyes down one more line and seeing that an IO-390 is only $800 more. That doesn't help me much, though, since Van's won't sell an IO-390 to anyone but a -14 builder.

Thing is, it doesn't seem like there are many other providers out there for a -390, if I were to keep entertaining this idea. The only concrete example I have is Barrett - I have a price sheet I got from them at OSH 2018, which lists the price of an IO-390 at $43k! Those extra ten horses sure ain't worth $10k to me...

So I'm just wondering if there are other options I might be poking around at out there. Or maybe I should just be happy with the angle-valve 360 and call it a day...
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Philip
-8 fuselage in progress (remember when I thought the wing kit had a lot of parts? HAHAHAHAHA)
http://rv.squawk1200.net
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  #2  
Old 02-23-2020, 09:06 AM
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DanH DanH is offline
 
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Location: 08A
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Phillip, one approach is to consider the primary requirement. The key is choosing what you're willing to compromise.

If the primary is to be a hauler, i.e. passenger and lots of baggage, do the 360 or 390 angle valve, short cowl, no prop extension. HP primarily benefits climb, heavy climb more so, and the W&B is friendly...nice and stable when loaded aft. The compromises will be more empty weight and a heavy stick in pitch when solo.

If it is to be a sports machine intended for lots of solo fun, buy a parallel valve M1B and a light prop. Have the ports and valve seats worked if you want to spend a few bucks. An AFP FM100 will flow a little more than the AvStar, as will an SDS throttle body.

I'm not aware of anyone having trouble with their Hartzell composite, and I suspect you'll get the money difference back when you sell the airplane.
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  #3  
Old 02-23-2020, 12:01 PM
DaveO DaveO is offline
 
Join Date: Dec 2012
Location: Greenfield, IN
Posts: 330
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Here is a thought, I purchased a non angle IO360, it had 10:1 pistons installed, it produced very close to 200 HP on a 7A. True, not a IO390. but there is more of those available. But you might be looking for only a new one too. Just my 2 cents.
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  #4  
Old 02-23-2020, 12:21 PM
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rv969wf rv969wf is offline
 
Join Date: Sep 2006
Location: Beaver, OK
Posts: 444
Default IO-360 with 390 cylinders

One other option is to purchase a LOW TIME IO-360A1B6 with the counterweighted crank and beefy heavy duty rods. Have the crankcase halves machined for the larger bore that the 390 cylinders have, get the case shuffle pinned to help prevent the case halves from fretting, keep the stock Lycoming 390 compression ratio pistons. Barrett converted many 360s to 390s this way. The problem is Lycoming is several months out on even getting the 390 cylinders to anyone. There are many of them flying out there like this. Just something to think about.
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Beaver, OK in NO MANS LAND
RV-6 IO360A1B6 C/S Hartz 200HP ?
Also Fly North American NAVIONs
Race car engine builder/Machinist/Fabricator 1982--present.
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  #5  
Old 02-23-2020, 04:43 PM
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N546RV N546RV is offline
 
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Location: Houston, TX
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Quote:
Originally Posted by DanH View Post
Phillip, one approach is to consider the primary requirement. The key is choosing what you're willing to compromise.

If the primary is to be a hauler, i.e. passenger and lots of baggage, do the 360 or 390 angle valve, short cowl, no prop extension. HP primarily benefits climb, heavy climb more so, and the W&B is friendly...nice and stable when loaded aft. The compromises will be more empty weight and a heavy stick in pitch when solo.

If it is to be a sports machine intended for lots of solo fun, buy a parallel valve M1B and a light prop. Have the ports and valve seats worked if you want to spend a few bucks. An AFP FM100 will flow a little more than the AvStar, as will an SDS throttle body.

I'm not aware of anyone having trouble with their Hartzell composite, and I suspect you'll get the money difference back when you sell the airplane.
Good feedback as always. My intent is to optimize towards utility, though I want to be careful of putting too much weight on the nose since I'm a big dude (6'4" and well over 200#, but working on the latter). That, in turn, is why I liked the combination of a lighter parallel-valve engine and a composite prop.

Another way to skin this cat would be to stick with the -370 and go with the Hartzell composite; the only real downside is the extra $4k or so required to do so (well, probably more like an additional $2k over the angle-valve + WW combo).

One thing that itches the back of my mind this whole time is not feeling like I have a good idea of what the choices I make will have on W&B, other than the very general "these things move CG forward and these others move it backward" sort of stuff. That lack of clarity makes it tougher to know whether, for example, adding the extra ~30# of an angle valve is "no big deal" or "possible solo forward-CG issue territory."

What I wish I had - and maybe this exists and I haven't found it - is some kind of database, which could call out the rough CG/weight of a bare airframe, plus approximate stations of the big items (engine/prop/battery/etc), and then I could work up some sample CG problems. Obviously the biggest issue here would be variance in the "bare airframe" numbers, but I feel like I could at least work sample problems for a variety of "bare airframe" examples and at least get some vague idea of where I sit.

It's also entirely possible I'm overthinking this - and I was pretty much told this exact thing by another local builder. "Just build it, you'll be fine." Which may be true, but for a guy who lives on numbers and rationality, it's also unsatisfying.

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-8 fuselage in progress (remember when I thought the wing kit had a lot of parts? HAHAHAHAHA)
http://rv.squawk1200.net
https://www.meetup.com/Houston-Area-RV-Enthusiasts/
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  #6  
Old 02-23-2020, 05:19 PM
Northernliving Northernliving is offline
 
Join Date: May 2005
Location: Boston, MA
Posts: 376
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Quote:
Originally Posted by N546RV View Post
OK, so I'm looking into options for a ~200-horse engine application for my RV-8. I'd been planning on a Titan IO-370, but last week I learned that the Whirl Wind no longer "supports" their props with the 370/375 engines. Still need to try and run down that reasoning, but in the meantime, I'm doing thought experiments.

The most obvious alternative is an angle-valve 360. I can get one from Van's for only a couple grand more than the Titan 370 I spec'd out last year.

BUT...

When looking at the engine list on the Van's site, it's hard to keep my internal Emperor Palpatine from moving his eyes down one more line and seeing that an IO-390 is only $800 more. That doesn't help me much, though, since Van's won't sell an IO-390 to anyone but a -14 builder.

Thing is, it doesn't seem like there are many other providers out there for a -390, if I were to keep entertaining this idea. The only concrete example I have is Barrett - I have a price sheet I got from them at OSH 2018, which lists the price of an IO-390 at $43k! Those extra ten horses sure ain't worth $10k to me...

So I'm just wondering if there are other options I might be poking around at out there. Or maybe I should just be happy with the angle-valve 360 and call it a day...
You will probably get as many opinions as there are members on this site. I decided to go with a hand crafted parallel valve injected 360, balanced with head work and valve work and the Hartzell carbon fiber CS prop. I'm expecting to get around 205hp +/- 5hp. I'm fitting an existing cowl and intake and I wanted to minimize rework but after looking at all available option, thought this was the best compromise/trade off. Not quite as much weight up front as an angle valve/BA prop set up, but more weight than what I have with a PV/12lb FP prop. I'll give you a PIREP in the next 6-8 weeks.

Dan outlined the trade-offs nicely.
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RV8 Based at ORH - Purchased
RV8 - The Project #83313 - Under Construction
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  #7  
Old 02-23-2020, 06:26 PM
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Carl Froehlich Carl Froehlich is offline
 
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Location: Dogwood Airpark (VA42)
Posts: 2,411
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This is what I did to project W&B on my build:
- A good friend has an RV-8 with a nice W&B. He is using the same Grove gear and parallel valve IO-360 (same as I will use) but with a three bladed MT composite prop (I will use the standard Hartzell BA CS prop). He is using two PC-625 batteries (mounted just aft of the firewall, one on each side). I will also use two PC-625 batteries.
- I took his W&B and corrected for the heavier prop. This lead me to move one battery to the aft location.

So - perhaps you can do a similar approach as you look at engine/prop combinations.

Carl
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  #8  
Old 02-23-2020, 09:26 PM
RidiculousM RidiculousM is offline
 
Join Date: Jan 2011
Location: Camarillo, CA
Posts: 99
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Just call Lycoming Thunderbolt and order a YIO-390 and put a carbon fiber prop on. Call soon they are backlogged about 9-10 months.
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  #9  
Old 02-24-2020, 07:39 AM
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DanH DanH is offline
 
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Location: 08A
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Quote:
Originally Posted by N546RV View Post
...I want to be careful of putting too much weight on the nose since I'm a big dude (6'4" and well over 200#...
Check your manual. CG range (normal) is 78.7 - 86.8. Fuel arm is 80, pilot arm is 91.78. So, fuel moves CG very little, and pilot mass moves CG aft. With a 390, metal Hartzell, and rear battery, the "Most Forward CG" example computed for the DAR was fuel fuel and a 170 lb pilot, which puts CG right at the forward limit. I used that example for realism; an FAA standard pilot going out to fly acro.

I'm 220+. Even so, when solo the stick is heavy for a high pitch rate, and it will run out of aft trim with full flaps in the landing configuration. I didn't install a 390 and a fastback turtledeck for speed, or for acro. Primarily I did it to haul Ms Patti's stuff.

Quote:
One thing that itches the back of my mind this whole time is not feeling like I have a good idea of what the choices I make will have on W&B, other than the very general "these things move CG forward and these others move it backward" sort of stuff. That lack of clarity makes it tougher to know whether, for example, adding the extra ~30# of an angle valve is "no big deal" or "possible solo forward-CG issue territory."
Just for fun I modified my W&B spreadsheet by adding a line for a negative engine-prop weight with a center 28" aft of datum...i.e. the effect of an engine prop lighter than a 390 and metal Hartzell. Thirty less pounds at 28" aft of datum moves the CG aft one inch, 60 lbs 2"
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Last edited by DanH : 02-24-2020 at 07:46 AM.
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  #10  
Old 02-24-2020, 09:07 AM
Northernliving Northernliving is offline
 
Join Date: May 2005
Location: Boston, MA
Posts: 376
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Quote:
Originally Posted by DanH View Post
Check your manual. CG range (normal) is 78.7 - 86.8. Fuel arm is 80, pilot arm is 91.78. So, fuel moves CG very little, and pilot mass moves CG aft. With a 390, metal Hartzell, and rear battery, the "Most Forward CG" example computed for the DAR was fuel fuel and a 170 lb pilot, which puts CG right at the forward limit. I used that example for realism; an FAA standard pilot going out to fly acro.

I'm 220+. Even so, when solo the stick is heavy for a high pitch rate, and it will run out of aft trim with full flaps in the landing configuration. I didn't install a 390 and a fastback turtledeck for speed, or for acro. Primarily I did it to haul Ms Patti's stuff.



Just for fun I modified my W&B spreadsheet by adding a line for a negative engine-prop weight with a center 28" aft of datum...i.e. the effect of an engine prop lighter than a 390 and metal Hartzell. Thirty less pounds at 28" aft of datum moves the CG aft one inch, 60 lbs 2"
Dan, what is your empty weight CG? My empty weight is 1012 lbs and my emty weight CG is right at 78.78; at the forward limit. This is with the battery in the bottom of the forward luggage compartment, a PV 360, grove gear and 12lb carbon FP prop. When I'm landing with full flaps solo at 210lbs, I'm adding slight forward trim, and when I have a 225lb passenger(the limit w/out luggage), I'm adding almost full forward trim on landing. Do you have any idea how much weight the fast back added? I would think minimum, but it's mostly behind you.
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RV8 Based at ORH - Purchased
RV8 - The Project #83313 - Under Construction

Last edited by Northernliving : 02-24-2020 at 06:07 PM.
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