Running hot

[Stangman]

Ok first off sorry not FE but helping a neighbor.
68 Camero 540 ci 9.0 to 1 compression (690) HP on motor.
F2 procharger with intercooler low in front of radiator.
Tranny cooler high in front of radiator but both are about 6 inches away.

He has had this set up for a while. He just freshened up motor and the only difference is an electric water pump. (Highest flow pump JEGS make) and he was told by Miezer and Ron Davis not to run a thermostat.

So now the problem is he can let it idle forever and never go over about 192-95 degrees.
If he goes on the parkway the temp creeps up slowly may take 5 miles or so but it goes to 220 then he can get off parkway and cruise around town and temp goes back down to 195. So I know some of the guys use an electric pump I was wondering do you use a thermostat. You would think cruising it would run cooler. A little help please so I can advise this Chevy guy.

[475fetoploader]

I ran a moroso electric water pump on a big block Chevrolet.  I ran no thermostat.  I custom tuned how fast the water circulated through the engine with some inexpensive moroso coolant restrictors that take the place of the thermostat. It’s possible to pump water through so fast that heat doesn’t scavenge properly. Both in the block, and the radiator. It sounds like his heat occurs more during driving.  I’m curious about air/fuel ratio, and timing.  Part load, cruising speed maybe something is unhappy that causes heat. Not enough timing, too much timing, a lean condition in an intermediate circuit etc. Also I have experienced an electric fan working good on a car not moving, that becomes a restriction at 50mph.  Hopefully the fan turns the correct direction, I’ve also seen that before.  Especially on refrigerated shipping containers, really causes problems when the evap fans go backwards.

[Stangman]

Thanks 475 all those things are good points and I asked him all those questions. He did have the car tuned by the same guy that normally tunes it. He’s running a Holley sniper system. I’m going to advise a restrictor. He showed me a few that he has. I really was interested in knowing about running a thermostat. All info welcomed

[GerryP]

Is he in a position to fit a mechanical pump and thermostat just to aid in trouble shooting?  I really don't think his issue is the pump or coolant flow volume, but you'd want to rule that out in the simplest way possible.

I know the flow issue comes up but most of the time, the flow volume is too low and causes the overheat.  If the flow is fast, it travels through the engine pretty fast and doesn't spend as much time dawdling around and getting really really hot and since it didn't get heat saturated, the radiator doesn't need to transfer as much heat.  If the coolant runs too slow, then it can get pretty hot in the engine before the radiator extracts the heat to start over.  You would need to run thermocouples around the engine and radiator to see what the deltas are.

[1967 XR7 GT]

Without a thermostat the coolant circulates to fast and doesn't stay in the radiator long enough to get cooled. Restrictions should work, it's trial and error to find the restrictor with the right size hole.

Another thing to think about is, 35mph and above, provide the air flow the radiator needs  for cooling.

[Dr Mabuse]

Never, ever NEVER drive on the street without a thermostat. Never.

He has computer controlled fuel injection, and no 'stat!

[Cyclone03]

What is he running for a fan ?

[Stangman]

He has a Ron Davis radiator and fan assembly duel pass made for his car and horsepower.

[machoneman]

We were frugal (cheap?) long ago in my drag race 427 Camaro, we simply gutted a thermostat of the spring and tower, ending up with essentially a flat plate with a hole in it. Worked fine btw but it was not a cruiser! Also, other BBC pals followed my lead in street cars but merely matched the hole size of a thermostat, with the center removed, in a flat aluminum plate. Worked for them too.

Funny, but with old style (non-cross flow) radiators it was hard to tell how fast the coolant was moving w/o a stat. But, with any cross-flow, leave the stat out and watch that coolant zoom! Yes, too fast and it doesn't have enough time to absorb engine heat. A stat or holed plate is needed.   

[jayb]

I always run a thermostat with an electric water pump.  I don't believe in the "too slow" or "too fast" theories of water flow through an engine, unless they are really, REALLY slow.

I think he has a basic thermodynamics problem.  At idle, the engine is putting out less heat, and his electric fans and radiator can keep the coolant cool.  Running down the road, the engine is putting out more heat, and the radiator/fan package is not able to keep up, so the coolant temperature is rising.  Plugged radiator?  Too many things in front of the radiator, blocking it?  If it was all new I'd say his radiator is not big enough or the intercooler and trans cooler are blocking too much air, but if he ran the package successfully before, then something has changed...

[Stangman]

Well previously he was using a regular pump and thermostat and it was fine. Now he is using a bigger procharger with more boost but just cruising I don’t think that should matter.

Today he put a 160 thermostat in it and it was a little better. But he has fans on all the time. I told him to put a 180 in and have fans come on at 195 and go off at 180. It was 90 plus degrees today and hot so I don’t see the benefit of a 160 thermostat it will never close after it opens especially with today’s temperature so it really is nothing more than a restrictor after it opens.
Oh today it was better on the parkway and a little worse around town with the 160 thermostat. I will keep you informed.
I’m glad you chimed in Jay I know you run an electric pump

[jayb]

For sure the extra boost DOES matter, and it matters a lot.  If he is running more air volume or boost going down the road, that will add a great deal to the heat.  He needs a bigger radiator.

FYI my 55 gpm CVR pump cools my NA 1000 HP SOHC just fine in traffic, on the freeway, and at the race track.  It's not the pump, it's the upgraded supercharger adding the heat.

[Stangman]

Just curious Jay do you have a crossflow and did you notch the frame rails and if you do have a crossflow did you get a wide enough radiator to notch both rails.

[fryedaddy]

thats how my motor was acting.it would overheat under power,but you could slow way down or idle and it would cool.my problem was it was sucking the bottom rad hose flat.but with a electric pump i dont think that could be the problem,unless it pumps more the faster you go.

[jayb]

Just curious Jay do you have a crossflow and did you notch the frame rails and if you do have a crossflow did you get a wide enough radiator to notch both rails.

Yes and yes, 31X19 radiator, 1-1/4" tubes, dual core.