oil cooler

dave wj · Post by **dave wj** » Wed Feb 07, 2007 12:45 pm

Hi all,

Can anybody help please:
I've built a kitcar with a Rover 4.6V8 engine. The timing cover and oil pump are from a 1990 3.9 RV8. I wish to fit an oil cooler and am looking at a mocal
unit. The easiest way of plumbing it in I believe would be to use a sandwich plate between the filter and the filter face on the oil pump to provide the supply and return to and from the cooler rad.
I've been onto Merlin motorspots who can supply the parts.
Is this a method which would work ok on the RV8 ?, and if so what sort of oil pressure drop if any would result?
My engine runs very hot during the summer months resulting in a significant drop in oil pressure. I'm hoping the oil cooler will go some way to improve the situation.

Many thanks for your help

Dave

GreenV8S · Post by **GreenV8S** » Wed Feb 07, 2007 12:53 pm

Make sure you fit an oil stat, as long as you do that there should be no problem.

dave wj · Post by **dave wj** » Wed Feb 07, 2007 1:01 pm

Many thanks for your swift response Peter. I'll most definately be taking the thermostat option.

All the best,

Dave

softdash3.9 · Post by **softdash3.9** » Wed Feb 07, 2007 11:28 pm

Running an oil cooler can in itself drop the oil pressure, due to the additional restrictions, food for thought

Don't automatically believe it will solve all our problems

dave wj · Post by **dave wj** » Thu Feb 08, 2007 8:45 am

Hi Royston, guys

Food for thought indeed. My problem I believe is that due to the engine running excessivly hot during hot days, the oil is thinning out and therefore allowing the pressure to drop, but more importantly if I go above 60 mph the engine temp starts to average out higher than I'd like and as soon as I slow down the fans kick in. Now it appears that just water cooling doesn't quite do the job and that has a knock on effect, thinning the oil and thus lowering the oil pressure.

If the extra oil cooling has the effect of reducing the engine temperature so normal speeds can be acheived and reduce the thinning effect on the oil, then I'm hoping any oil pressure loss due to oil cooler fitment will be compensated for by the oil not thinning so much due to the reduced engine temp.

On relatively cool days both pressure and temp probs are within reasonable limits although I have to manually switch my rad fans on as soon as I hit town traffic otherwise temps rise very quickly.

I'm paranoid about cracking my block.... being a 4.6!!!!!!

Hoo Whee! catch 22 I guess.

Hope this makes some sort of sense.
Incidentally I've got the biggest rad I can fit in my kit car. RPI seem to think it's big enough to cope. Oh and a new water pump.

Thanks all for your input on this.

Cheers,

Dave

Ian Anderson · Post by **Ian Anderson** » Thu Feb 08, 2007 9:25 am

I would hazard a guess that your radiator is not up to the job.

Or it is up to the job but due to placement it cannot get a decent airflow through it.

What type of kit and how big a radiator

Ian

jrv8 · Post by **jrv8** » Thu Feb 08, 2007 9:47 am

Hi,
What kitcar is this engine in ?
Jim

softdash3.9 · Post by **softdash3.9** » Thu Feb 08, 2007 9:50 am

Have you got some oil pressure readings hot/cold and what are the engine running temps against usage?

Was just wondering what your expectations are? are they too much possibly? i.e. are you panicking for nothing.

RV8's aren't renowned for their oil pressure, are you using the correct grade of oil?, are the gauges accurate? just wanting to throw a few ideas in the ring to consider

My vitesse has @ 25-30psi at tickover when hot, no oil cooler fitted although I have a correct SD1 type in the garage.

I used her on the hottest days last year in @ 30 degs whilst cruising down windy lanes, temp was up a little but was acceptable, can't remember the temps though

dave wj · Post by **dave wj** » Thu Feb 08, 2007 10:58 am

Phew now where do I start,

The kit is a Luego Viento which is a larger lotus 7 style with enough room for easy fitment of the V8. The rad is quite a bit larger than would normally go in the standard Lotus 7 kit. Unfortunately I can't give you the size as I'm at work at the moment, but RPI seemed to think it was a good size.

Oil pressure when hot is around 30-35psi at 2000 rpm and somewhere in the region of 5-8 psi at idle warning light stays off.

When cold it is around 50psi and 20psi at idle (when first starting up)

Air flow through the rad is good as it fills the opening in the nose cone and sits only about 2-3 inces back.

oil is 15W40 (maybe I should try 20W50)

The only other issue I can think of is underbonnet heat. Would this have a dramatic impact on overall engine temp?

I've heat wrapped the exhaust manifolds to try to lower this a tad, but curiously this seems to have the effect of bringing the rad fans on quicker, with minimal effect on engine temp.
Strange one that.

I understand that RV8's are oil volume dependant rather than pressure so I've not been overly concerned, but the overheating during the hot days is a worry, and as I've read on several posts that the oil is a vital component of the engine cooling process, then an oil cooler seemed a logical step, or is my ignorance showing through?

Thanks again for all your advice and interest guys. This is a bit daunting for us newbies to the V8 scene.

All the best

Dave

badger · Post by **badger** » Thu Feb 08, 2007 5:14 pm

Your hot oil pressure is just fine, the book figures are 35psi plus or minus 5psi at 22-2400rpm. No idle figure is quoted, the low pressure switch operates at 3 or 4 psi normally. Get the thin oil out and put in the correct 20W50 (assuming it's an old-style oil pump and not an interim serpentine front cover?) and that'll give you another few psi as well.
Cold oil pressures are irrelevant on this engine (and most others as well!), most std engines rarely make the nominal 35psi so yours must be fairly ok especially with the thinner oil in it.

dave wj · Post by **dave wj** » Fri Feb 09, 2007 8:40 am

Thanks for the info Badger, I think I'll try to sort out the underbonnet heat for starters as the tendency to overheat in the summer is a real concern.
I guess the oil cooler option will be a last resort (expense wise anyway)

Incidentally, the rad covers an area of 24" x 16" and just squeezes in so unless I have an ally rad made, I have no scope in that area.

Thanks to all you guys for your help and info.

Cheers

Dave

mikeinatruck · Post by **mikeinatruck** » Fri Feb 09, 2007 8:58 am

Have you considered 'Wynns water wetter' it prevents coolant from forming air bubbles when the tempretures are high, worth a try.

Have you actually tested the tempretures accross the rad when its hot to see what the flow rate is like?

Ian Anderson · Post by **Ian Anderson** » Fri Feb 09, 2007 9:09 am

Dave

What is the area like just behind the radiator?

If it is cluttered the air flow through the rad will be reduced.

I read somewhere that you can get away with about 1/6 of the area of the raidiator as an inlet space but need pretty well full area for the exit air.

Also once the air has gone through the radiator is there somewhere for it to go? What about extra fins to release air / heat from engine bay?

Ian

dave wj · Post by **dave wj** » Fri Feb 09, 2007 9:28 am

Thanks, Mike , Ian.

I've tentatively looked at water wetter, again if I can't bring the temps down by conventional means, then I may look at that. Would you recommend adding to existing 50/50 glycol based coolant or drain out, use fresh water and just add water wetter to that. I must admit, I don't fancy draining down again, as after changing my water pump, trying to remove air locks etc was a nightmare.

Ian,

You may well have something there, although there is a decent amount of room behind the rad even with the fans being inboard ( they pull the air through the rad). I'm wondering about the airflow under the bonnet.
With the car being a lotus 7 style (but larger) the rad is very close to the underside of the car, therefore I'm assuming the air would have easy escape underneath the car, but I'm not so sure. Anybody familiar with air flow under a bonnet?
There are large clearances around the exhaust manifolds as they exit the side of the car, so air can escape here.
There are no louvres in the actual bonnet.
My plan is to create some grilles or something similar in the bonnet to aid airflow. The bonnet being GRP I've got to create something to hold mesh and still look half decent. Any ideas very much appreciated.

Thanks again guys,

Dave

Ian Anderson · Post by **Ian Anderson** » Fri Feb 09, 2007 10:21 am

Look in my Avtar

that is the rear of the GT40 with a stainless pannel and "le mans" style grill to allow heat to escape (Mid engine car)

But the GT40 has side scoops (Air into engine bay) to assist with heat and more vent in the tail section near the number plate.

The rad on mine is up front and is really open to allow heat / air to escape (also Ali rad) Ali Rad is 32cm by 76cm if memory serves correct with twn fans for the slow stuff!

Ian