Additional Oil cooling?

[DDS]

I've got my engine out and am resolving what I hope I (we - thanks!) have correctly diagnosed as an oil cooler leak. I got to wondering about adding an auxilliary oil cooler - I don't want the extra complexity if it isn't required, however I would like to look after the engine. It is a 2056cc, big valves, ported, 9.5:1 CR, cam etc... Likes to rev, but isn't exactly the wildest T4 out there.

Is the stock cooler adequate?
At what level of build/under what circumstances is additional oil cooling required?

TIA, Dave

[Treemn]

I had the same displacement,8.5 cr & rods modded for piston cooling. Saw 240* before adding external coolers. (plate type
installed in series behind non foglight grilles.Never over 220
after. HTH
Jeff

[Dave at Pelican Parts]

An external cooler is required if your oil temps are excessive with just the stock engine-mounted cooler. There are enough variables in how the engine oil gets cooled that you can't reliably say ahead of time if a given engine will or will not require additional oil cooling.

--DD

[lmcchesney]

DDS, it's like Dave said. But, I read that you removed the engine because of the oil cooler leak. Soooo, that means you have been runing this engine combination, correct? If that is true, have you been monitoring the oil/engine/EGT temps? As you have seen from Jeff's post, you need to know the temp to determine if you need to lower the oil temp. DD and others can help you determine the oil temp. such as direct oil temp measurment to activation of the warning lignt.
L. McC

[Jake Raby]

Gotta have gauges.... Incremental gauges that read numbers instead of just Red and green..

Remember, cooling the oil is just 1/2 of cooling the engine. Cool oil doesn't cool the heads. Not one bit.

Also, most temp problems are the fault of mistuning... most of them can be tuned away and save the install of a big cooler- thats just a simple band aid.

[DDS]

Thanks. I only have an oil temp gauge, but it has a numerical deg F scale. I think I've had it as high as 210. Usually, 170-190 IIRC. (I've only been looking for problems) To Jake's point I've been playing around with the tuning. Pretty close on the webers now, keeping it a bit rich. I have a few holes to plug in the tin too, and haven't yet tried to optimise the timing. I believe John at aircooled .net suggested 35deg at 3500 rpm and I've left it there.

This all tells me that the stock cooler may be adeqate and to hold off and watch the temps before adding another system's worth of potential leaks. Thanks for the advice!

What is considered and ideal 'maximum' working oil temp?

[Jake Raby]

Does it have a stock cam??? If so, go ahead and install the external cooler...

210 is NOT hot on oil... its a great operating temp. I consider 230 hot.

[DDS]

Interesting stuff as always. Thanks Jake. FAT FC442, .465, 290 deg advertised, HD single springs. 42DCNFs, 44mm intakes, 9.5:1 (might be a bit higher)
Beyond higher average rpm, what effect does cam grind have on oil temp? Would my cam run hotter or cooler than a stock cam?
I haven't run it in mid summer, so I'm not totally clear on its max at this point. Thanks for the 210 benchmark.

Dave

[Dave at Pelican Parts]

I'll let Raby address the cam question, as he's done about sixty zillion more hours research into cams than I have.

Oil viscosity tests and other oil tests are done at 212F, the boiling point of water. I consider that to be the oil's normal operating temperature. I consider 250F to be "too damn hot", and 230F to be "hot".

Run the motor. On really hot days, keep an eye on the temp gauge.

--DD

[Jake Raby]

The cam effects the engines efficiency more than anything else... I think even more than the CR..

A cam that does not match the CR simply creates a hot burn that promotes inefficiency, and the creates heat- period... Head temp and oil temp.

It never ceases to amaze me how much guys put into the oil temp gauge, they think that as long as the oil temp is cool, the engine is cool- NOT... You MUST take head AND oil temps measurements to accurately monitor the engine.

The stock cam has little overlap, and tight lobe centers, due to this it promotes high cylinder pressures and heats up the engine fast.... Thats one reasobn VW used it was to get the engine to operating temp faster in cold climates... These cars were never designed to work their best here in the states!

If you add bore and CR to the stock cam, that sucker will be a fireball for sure, I've done it.

[DDS]

Of course, I should have got that - realized vs theoretical/static/mathematically derived CR. thanks.

So I guess mine has so far demonstrated that it isn't a fireball, though I do get the point about the heads being way far away from the oil. I'll have to figure out a way to monitor all the temps, or just keep the tuning conservative, and use the oil as a rough benchmark. Hmm - Can you use the D-jet CHT to drive a temp gauge? I'll seach the archives....

I ordered a new oil cooler, and for now will just use the stock unit and watch the temps.

Many thanks again.

Dave

[Jake Raby]

The oil cannot even be used as a benchmark! Oil temps are dependant upon friction. Friction is directly related to RPM. Heads are dependant upon load...

You gotta have both instruments! Benchmarks don't exist.... well they used to, to the guys that ended up as statistics, and open wallets until they listened.

[DDS]

Slowly, slowly, I get the point. OK, I don't need a lot of convincing, the head work cost plenty. Any suggestions on the best rig for monitoring head temps? Monitoring this would be a really good idea while tuning (learning) also.

Dave

[Jake Raby]

www.westach.com has great instruments....

[Dave at Pelican Parts]

The VDO instruments that Pelican sells include a CHT gauge. This has the ring thermocouple that goes under a spark plug. You may need to do some light grinding to give the "tail" of the TC somewhere to go, but nothing too extensive.

--DD