Heat Loss Through An Oil Cooler 1

[Scott367]

I have a NA 331 ci engine making about 500 hp. My cooling is what I would consider acceptable but no more. I have maxed out what is available with an aftermarket radiator. I am thinking that since I have an oil capacity of approx 12 quarts I could lose alot more heat through an oil cooler. Is this a good use of funds or a waste?

 

[reidh]

An oil cooler won't be that much of a benefit, as an oil cooler will warm the air infront of the radiator, as well as restrict the air flow through the radiator. You may have a marginal gain, but I would categorize this as a waste of funds.

-Reidh

 

[evelrod]

It depends greatly on how you intend to operate your vehicle. In racing, such an engine would demand a heat exchanger in the oil system. On the other hand, a street driven car might not...12qts is a lot for a street car to bring to operating temp just about anywhere, even here in Socal! True, you can use an oil cooler with a thermostat in the system for street, but I have always shied away from the added complication.

On many import sport cars, heavy duty trucks, etc. an oil cooler is std. The only street car I have installed an oil cooler on was my 290hp (at the wheels) T Coupe and, even that was a smallish piece. I use a 19 row Mocal on my ~130hp Mini and ~185hp Lotus...both with 10+qt.capacity wet sump systems. I did crew (back in pre history) on a IMSA GT Pantera with a 26 row Mocal on a 500+hp, 24qt dry sump system. On a hot summer day, oil temps hover around 200f on all these applications.

My vote is you probably won't need a cooler and, even if you live in Phoenix, you might need only a small one.

Rod

 

[evelrod]

Reidh.
Just do not mount the oil cooler in front of the radiator,
I don't. As a matter of common sense, I mount them with their own seperate ducting so the radiator and under hood temps are not affected by hot air off the oil cooler.

Rod

 

[patprimmer]

Like Rod said.




Regards

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[reidh]

Evelrod,

That would definitely work. Keep in mind there is no free lunch though (increase in drag caused by doing this).

-Reidh

 

[evelrod]

In my experience (vast in this particular area---broken engines) it is always better to keep 'er runnin' till the checker, then try to work out the aero. "To finish 1st, first you must finish." I've seen them come in from a qualifying session with water at 240+ and oil at 270+ on more than one occasion. That's great for Rou$h...I just do vintage. Besides, the ultimate oxymoron is comparing my Mini Cooper or my Lotus Cortina with anything aero! ;-)

Rod

 

[patprimmer]

Here, the old school Mini was also known as the flying brick because of the aero, or more precisely, lack of it.


Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[reidh]

Yeah, I guess my aero background is coming back to bite me. When packaging a piston engine under a cowling for an airplane, we always stacked the radiator and oil cooler to reduce drag. We could live with the slighty higher radiator air restriction since the engine doesn't make as much power at altitude, thus rejecting less heat.

I was always told I had my head in the clouds, you guys are just proving it.

-Reidh

 

[Scott367]

I run this car, 1965 Mustang, on a closed course on fun run days. Open track run as many laps as you like for the entire day. The car may see 15 to 20 85 to 90 sec laps before a cool down. Since the oil is hotter I planned on putting the cooler behind the radiator where I will still have a delt in T.

 

[evelrod]

Scott, that sounds like the plan. I raced 1964 HiPo Fairlane in 64/65 sans oil cooler. I think the total oil capacity was something like six qts. and I ran without the mechanical fan. I bought the car in Pueblo, Colorado but drove/raced/hot rodded it all over the southwest until it was destroyed in a TA in Gardena, California in '66. Too bad, it was a great little car (a bit over 100,000 miles). The 289 did have a couple of problems that cropped up, one biggie was the timing chain tended to break and squirrel up all the valves. The last time I had Joe Reith do the valves I installed a roller chain system that was supposed to be stronger/unbreakable...never got the chance to find out, car was crashed that summer.

Best of luck.

Rod