Baffle mounted oil cooler in -8

All,
I live in a very warm section of the country (middle Georgia) and so want to make sure I have adequate cooling. I have been researching the baffle mounted oil cooler in a -8 here and elsewhere on the web.

Since the -8 oil cooler has to be mounted lower than on the side-by-sides, much of the oil cooler is blocked by the #4 cylinder and thus it doesn't work as well. Some have opted for a different more efficient oil cooler (Stewart-Warner, I think). Others have located their oil cooler on the firewall. I have a firewall mounted battery and thus, the firewall is a bit crowded. Also, I would rather not have to buy another oil cooler. I have the Niagra cooler that comes with the FWF kit.

Some have fabricated spacers that move the oil cooler back some. This looks like it improves airflow a little more. On one website someone used Z brackets (same ones used on the fuel tanks) to move the oil cooler way back. I have fabricated a 1/8" spacer that I plan to put between the oil cooler doubler bracket and the baffle. But, I don't know if that will make a significant difference.

The reason for my post is that I would like to update the body of knowledge on this topic. Those of you with flying 8's (particularly in warm climates), how is your baffle mounted oil cooler mounted (per plans or modified), which oil cooler do you have, and how is it performing?

Thanks,

Tony
Take this for what it's worth. You're going to get lots of conflicting advice, but here is my experience.
I recently built 2 nearly identical RV8's. I'll call them #1 and #2.
#1 has a an ECI O-360 A1A, 4164 carb, 8.5 to 1 pistons, dual mags and a Positech(Vans cheapie) oil cooler mounted on the aft baffle. Also it has the Vans oil shutter installed. Also, standard Vetterman exhaust.

#2 has an ECI O-360 A1A, 3878 carb, 9 to 1 pistons, dual mags and A SW 8406R (expensive) oil cooler mounted on the back baffle. The shutter has been rigged, but I left it out for the summer.Also, standard Vetterman exhaust


Both #4 cyl. aft baffles were opened up completely inside the doubler to get the most airflow thru the cooler.

The airplanes are hangared together, and have been flown side by side a couple of times. What I have observed so far is:
When the planes are started and taxied together, take off in formation, flown to cruise altitude together, and then established in cruise, we get nearly identical temps. CHT's the same, EGT's the same, oil temps the same, fuel flows the same.
It should be noted that both plane s have Dynon D180's, with the EGT probes in the identical spots for both planes( 2 inches from the base of the exhaust flange). Also for anyone interested the floscan 201B fuel flow transducer's are mounted to the outlet side of the gascolators.( 30 gal fillup's have less than .5 gal +/- accuracy).
Incidently the positech cooler was slightly obstucted by the fully open shutter,which still blocks some airflow.
CHT's around 360, EGT's 75 deg.ROP, oil temps around 185-195.

It gets hot here in Cincinnati in the summer too.

If I had it to do over again, I'd get the Van's EA Oil Cooler II(it fits the doubler better than the positech).

This summer I'll do a very good comparison with lots of numbers.

I apologize in advance for whatever protocol or reg. I have busted.

Per Plans in Houston

I decided to build the baffle-mounted cooler per plans, using the FWF kit cooler, and haven't had any problems flying around Houston for three years. I have occasionally had to level off in climb when climbing out of Phoenix after a fuel stop in the summer, but that was understandable with outside air temps quite high. I did do significant reinforcement to the left rear corner baffle area, and haven't had any cracking, but the cooler is essentially mounted right where the kit has you do it.

I'd do the same thing again.

Paul

Guys Larry Vetterman has cracked the code with complete control over oil temps, by removing the vernatherm and installing the oil cooler bypass spring and plunger in the filter housing, a ball valve on the line to the oil cooler, controlled with a vernier from the cockpit. The part numbers for the oil cooler bypass are SL62415 for the oil bypass plunger and 69436 for the spring.

rocketbob said:

Guys Larry Vetterman has cracked the code with complete control over oil temps, by removing the vernatherm and installing the oil cooler bypass spring and plunger in the filter housing, a ball valve on the line to the oil cooler, controlled with a vernier from the cockpit. The part numbers for the oil cooler bypass are SL62415 for the oil bypass plunger and 69436 for the spring.

Click to expand...

Bob,
Are details available somewhere?
Thanks!

Per the Plans

Tony:

Not knowing any better, I followed the plans. I have Van's standard oil cooler mounted on the baffle. My engine is a Lycoming O-360-A1A.

During summer flying in the Dallas area my oil temps are typically 175 to 185. I've never seen it go higher than 185.

During the winter months, it's difficult to get the temps up into the 170 range much less the "magical" 180 range. Usually the temps are in the 150 to 160 range. But winter is short here. I have not blocked off the opening to raise the temps.

I have spoken to a Lycoming rep about the temps, worried that I'm not burning off the moisture in the oil. He said that since I change oil and filter every 25 hours that this should not be an issue.

Regarding Paul's remark about strengthening the left corner of the baffles to prevent cracking, this is a common concern. With my finish kit, bought in November 2002, there was an extra angle included for strengthening this area (in other words I have the baffle metal and the angle metal in that corner). I'm not sure what current plans call for. I only have 285 hours on the airplane but so far I have seen no cracking in this area or any other for that matter.

Chris

rv8180 said:

Bob,
Are details available somewhere?
Thanks!

Click to expand...

Nope, unless you call Larry. Long story short:

Buy a 3/8" brass air/oil/water stainless ball shutoff valve from the aviation aisle at Tractor Supply (I think the valve cost me $5.00)

Remove vernatherm

remove thermostatic bulb and spring from vernatherm by removing the clip and separating the bulb from the cap

put the vernatherm cap back on the oil filter housing

remove the top cap on the oil filter housing

place oil cooler bypass plunger and spring in oil filter housing (part #'s listed in previous post)

put the cap back on

attach the 3/8" ball valve to the supply side of the oil cooler

fabricate a new arm for the oil cooler valve and hook up a vernier control, install the control on your panel

Now you have complete control over oil temperatures. Larry said he was able to drop his temperatures significantly...I was sold on the spot with this great mod.

rocketbob said:

Nope, unless you call Larry. Long story short:

Buy a 3/8" brass air/oil/water stainless ball shutoff valve from the aviation aisle at Tractor Supply (I think the valve cost me $5.00)

Remove vernatherm

remove thermostatic bulb and spring from vernatherm by removing the clip and separating the bulb from the cap

put the vernatherm cap back on the oil filter housing

remove the top cap on the oil filter housing

place oil cooler bypass plunger and spring in oil filter housing (part #'s listed in previous post)

put the cap back on

attach the 3/8" ball valve to the supply side of the oil cooler

fabricate a new arm for the oil cooler valve and hook up a vernier control, install the control on your panel

Now you have complete control over oil temperatures. Larry said he was able to drop his temperatures significantly...I was sold on the spot with this great mod.

Click to expand...

Thanks!
It sure sounds good and workable.
Due to my engine selection, I'm going to really consider this.

Oil cooler vertical position

I installed my Vans oil cooler per plans. Originally I had adequate cooling; during low level flight in hot weather the oil would be in the 190s, at high altitude with warmer than standard temps in the low 200s.

I had some baffle cracking at about 300 hours, and in the process of rebuilding and reinforcing the baffle I moved the cooler up about 1/2" vertically. This has a surprising effect on the oil temps, which are now consistently 10-15? less than before.

My conclusion is that Vans setup works fine even in hot conditions, but you should 1. reinforce and/or brace the baffle to prevent cracking, and 2. mount the cooler as high as possible without rubbing the cowl.

I have an IO-360-A3B6D and fly in extreme (for me) temperatures (in both directions). -20 in the winter and 90+ in the summer. I have no oil temp issues and this is my setup.

The parts:











YMMV, but I hope this helps.

apatti said:

The reason for my post is that I would like to update the body of knowledge on this topic. Those of you with flying 8's (particularly in warm climates), how is your baffle mounted oil cooler mounted (per plans or modified), which oil cooler do you have, and how is it performing?

Thanks,

Click to expand...

My oil temps were way too hot initially, so I ended up getting a new oil cooler -- a Stewart Warner 8406R. It's a direct replacement (no baffle modification required) for the Niagra 20002A that came in the Vans FWF kit. This resulted in the often-reported 10-15 degree drop in oil temps for me. In retrospect, I wish I had gone with a slightly bigger cooler originally -- one that's an inch wider and has a few more fins on it.

I've never had a CHT problem, but my oil temp is still hotter than I want it to be in the summer. For example, takeoff from sea level 95*F and climbing to 9000 feet results in an oil temp of about 220 at the top of climb. That's with CHTs in the mid 300s and climbing at 120kts. More than 5-6 touch-and-goes with ambient temp above 85*F results in an oil temp of about 215.

I have standard pistons, fuel injection, and dual electronic ignition. Maybe this combination is putting out more than 180 HP and that's why my oil temps are hotter than the carb engines mentioned here. Maybe it's just a slight difference in cowl construction. Who knows.

I do know that an RV-8A builder near me (same climate) rarely sees an oil temp over 180 on any day - even during break-in. He has an injected, dual electronic ignition engine too. His secret? He installed the wider oil cooler because Vans sent it to him by mistake and he didn't know any different. Since the cowl on the -8 prevents the cooler from being installed as high as on side-by-side models, the only way to alleviate blockage by cylinder fins is to make it wider.

Your mileage may vary. It seems that every plane is just a little bit different in this area. It may be easiest to just go with the stock setup and fix it later if you have a problem. If I were building again, though, I'd use the biggest and best cooler I could fit on the baffle. You can always cover it up after the fact.

Thanks for all the replies. It does look like there is wide variation here. You'd think if the standard setup works in Houston and Dallas it would work here in Middle GA.

I plan to double the thickness of the baffle section where the oil cooler is and mount the cooler on a 1/8" spacer all around. I'll see how that goes and, if necessary, modify it later.

Thanks again.

rocketbob said:

Now you have complete control over oil temperatures. Larry said he was able to drop his temperatures significantly...I was sold on the spot with this great mod.

Click to expand...

I dont get it. It is my understanding that the vernatherm prevents most of the oil flow through the cooler when the oil is cold, then allows flow through the cooler when the oil heats up. So, how would changing this system to manual control result in a drop in oil temperature? If thats the case, it would seem to indicate that the original vernatherm was not working properly.

Am I missing something? I would like to drop my oil temperatures a bit myself, but I dont see how making it a manual control system will help me accomplish that.

erich

erich weaver said:

I dont get it. It is my understanding that the vernatherm prevents most of the oil flow through the cooler when the oil is cold, then allows flow through the cooler when the oil heats up. So, how would changing this system to manual control result in a drop in oil temperature? If thats the case, it would seem to indicate that the original vernatherm was not working properly.

Am I missing something? I would like to drop my oil temperatures a bit myself, but I dont see how making it a manual control system will help me accomplish that.

erich

Click to expand...

Not sure Erich, you can call Larry Vetterman and I'm sure he'd fill you in on the details. I'm guessing there is less of a flow restriction with the vernatherm closed (hot) than there is with the oil cooler bypass and spring. The other possibility is your vernatherm is not closing completely thus allowing oil to bypass the oil cooler.

A northern perspective

Tony,

I live in the Portland, OR, area and can give you another perspective. My RV-8 has an IO-360 M1 with 9.2 to 1 pistons, and one LightSpeed ignition. I used Van's Firewall Forward Kit oil cooler and mounted it to the back of the baffle according to the plans, with some extra reinforcement to the rear corner of the baffle. I put the cooler as high as possible on the baffle. I was very careful to fit and seal the engine baffle to the engine and the cowling. My oil cooler is almost too efficient. In the summer (90+ degee temps), I fly with most of my oil cooler airflow blocked off with an aluminum plate across the back of the cooler. Normal cruise temps are cyl heads about 340 and oil about 180. During long climbs, cyl head temps reach 380 and oil temps will reach 200 or less.

In winter (temps in 40's), with the oil cooler completely blocked off, my cyl head temps run around 300 or slightly less and oil temps are about 140 to 150--way too cool. I have to block some of the cowling outlet cooling airflow at the bottom rear of the cowling to get oil temps up to 170 to 180, and cyl head temps up to 320 or so. I do this with a 3" x 5" aluminum plate clamped between the exhaust pipes to block airflow out of the cowling.

I suggest that you use Van's normal (cheap) oil cooler, mount it according to the plans high on the back of the baffle, and that you not use Van's oil cooler shutter because it blocks some of the airflow in the open position. If your baffle is tightly sealed, you should get plenty of cooling for your oil.

Dan Miller
RV-8 N3TU 530+ hours
Battle Ground, WA