Oil cooler location

[svanarts]

Hi guys,
My RV-4 is already flying but I'm not really happy with the oil temperatures. I keep hearing how the 4 is the coolest running of all the RV series but I'm just not seeing that. I currently have my oil cooler mounted on the left side of the firewall just above the "step" where the rudder pedals are. I want to move my cooler to a location that will allow more airflow. I'm still trying to decide between behind the #4 cylinder on either the baffling or the engine mount, or in front of #1 (or is it #2). Fabricating the mounts for any of these locations has me stumped. Any brilliant or even stupid ideas out there?

Hey, let's have a poll while were at it!

[aerial]

Let me qualify my response by saying I don't know. Really I DON'T, but to me it would make sense to have as cool as air as possible running over the cooler. That would mean an air duct, or getting it out of the hot air after it's flowed past your cylinders or exhaust stacks. In front would make sense, but where to put it? It's not like an auto where you can hang it in front of your radiator.

[svanarts]

I'm actually starting to lean toward putting it up in front of Cyl #1 or is it #2. Anyway where ever there is more room. Maybe having some of that oil up there would help the CG. You just can't have enough weight on the nose in a RV-4.

[aerial]

..... You just can't have enough weight on the nose in a RV-4.......

What's your weight and balance like? How heavy of a person can you carry in the back, how much baggage before you start having trouble with your glide and flare?

You are not the only one who has eluded to this. Rob (of http://www.advanced-control-systems.com/ fame) gave me a ride in his RV-4 when I was up in Oregon. I asked him to do a barrel-roll, and he quickly quipped "How much do you weigh, you have to watch the weight and balance on these 4's." I didn't ask him to elaborate and was content with the aileron roll he demonstrated. (It was quick!)

Have you tried any spins? With someone in the back?

[svanarts]

The heaviest person I've had in the back was 180lbs so that's my personal limit right now. I really need to reweigh the airplane though. It really helps if you put a CS prop on an RV-4. I did the W&B for my friend's RV-4 with an O360 and CS prop, he could carry a 375lb person in the back!

The RV-4's reputation for being tail heavy is true.

[aerial]

I'm doing ground school ASA DVD style and they talk about rear CG leading to a problem recovering from spins. That's why I asked. But what do you notice in the flight characteristics when loaded in the back? Or is it more of a "gut" feeling with heavier stick weight?

[svanarts]

The only time that a heavy passenger is really noticable is flying the pattern in a landing approach. The tail gets really heavy with a big boy in the back. Makes you really pay attention in those base to final turns. Most if not all RV-4 pilots will not do spins with a passenger.

[svanarts]

Anyway, back to oil coolers. It looks like I won't be able to put it up front unless I can find some fittings that won't interfere with my lower cowling. It's just flat too tight up there with the cooler I have. I can't remember the exact make and model but it's roughly the size of the Stewart-Warner coolers. For now it will have to go behind the #4 cylinder.

[aerial]

For now it will have to go behind the #4 cylinder.

I was thinking about it (couldn't get online this weekend because the phone lines were down...life in the country) But putting it in front might make that cyclinder run hot and that's not good, up high and behind sounds like the place, that way it's not behind the exhaust which gets hotter than the cyclinders.

[svanarts]

Possibly. I wouldn't think it would rob too much cool air from that front cylinder. After all, the cooler is under the front baffle and most of the cooling air is still blowing over the cooler opening and straight toward the cylinders. I know that putting the cooler behind #4 does raise that cylinder's temperature a little. But not enough to really worry about. I suspect the same for #1. I still hope to find a way to mount it up front.

[flysteve]

Hi Iv seen one on top of the case jest in front of baffly

[RV-4]

Hello
My oil cooler is located behind the # 4 cylinder and I'm still getting too much cooling out of it. So far I have installed a full back plate to it and I replaced the oil temp gauge thinking it might have been the problem but no,it's still too cool.

In the summer, I get about 150-160 degrees and in the cool fall weather I get about 120-130 which it way too cool for the health of my engine (0-320 E2D ).I'm getting oil foaming which isn't good. I currently thinking about removing the whole thing, What do you guys think of that??/

RV-4
Montreal,Canada

[Dan A]

Hi Guest,
Maybe you could try bypassing the oil cooler. You need to get that oil temp up!! Good luck
Dan

[rv4guy]

I have my cooler mounted in front of the #1 (LHS) cylinder and it works great. Yes, you need to have 90 deg fittings there in order for the oil lines to clear the lower cowling.

I noticed in one of the posts, someone pointed out they were getting too much cooling - this is not because of the oil cooler! Your vernatherm (the valve that controls oil flow to the cooler) isn't working!

...and my next peeve - have you guys actually flown in an RV4? or any other tandem seat airplane?...with a passenger? When your CG moves aft, your stick forces become lighter and vice versa. The tail doesn't get heavier (as far as the pilot is concerned). Lighter stick forces mean you're more likely to overload the airplane unintentionally - and since you're probably already over the aerobatic gross weight, you're also more likely to bend the airplane and hurt yourself. I also don't believe for a minute you can put someone in your back seat that is 375 lb (was it??). My back seat weight limit is 240 lb. I had a short friend 'try out' the back seat (on the ground) that weighed around 280 lb. The stick wouldn't move past 'elevator neutral' before hitting his gut - NOT gonna happen in my airplane.

OK, enuf!

Happy flying, but be careful out there and don't try stuff you don't understand!

m.