Overheating Help Please

[BITTEN]

Hi Team
Some of you might remember our cobra as BITTEN now BITES in custom orange paint. We may have upset a few by not sticking to originality but that’s our thing.
My Dad and brother and I have built BITES from scratch over the last 20 years.
She looks great and the 331 is unbelievable. I must admit that we probably went too aggressive with the Cam as it’s making power past 8,200rpm which robs torque but it’s a light car.
To my issue. She is on the road and handles amazing with the Penskes however she gets way too hot for my liking. Sits in the 90 degree C mostly but climbs to 110 (at that point I stop or get to open road and it drops to high 90’s or low 100’s).
I have just installed a brand new highest output SPAL thermo fan - no difference.
Removed the stupid accusump (doesn’t hold primed air pressure) to see if it was blocking air flow- no difference.
It has an electric water pump and was professionally tuned with a Link Xtreme ecu and a 3 core alloy radiator.

It is possible that the cam is retarded to a point that’s contributing but changing that is a major issue (engine out and retune).
Any help will be appreciated greatly

[xb-60]

Firstly, congratulations on your family build of the Cobra. Does "build from scratch" mean that you actually designed and built the chassis as a clean sheet build? Whatever, building a car together as a family is a great project and a great achievement.

So, overheating ..... at 90deg C most of the time, that should be no problem at all. Even with sometimes up to 110deg, if you have sufficient pressure capacity in your cooling system, and it's in good condition - that also should be not a problem. Under what conditions does the temp reach 110?

Cheers ...and a happy, safe and cool New Year to you!
Glen

[Tommy]

I agree with Glen on the temp. With proper coolant and pressurized system, I don't start getting concerned until the temp reaches 110C. At that point I start watching it closely and shut it off if it reaches 115C. . . . Congrats on your car.

P.S. Many people don't understand how a car's cooling system reaches a stable operating temperature after the thermostat opens and the engine is running at a steady pace. The amount of heat the ambient air can remove from the coolant via your cooling system (i.e., radiator, fan, pump, etc.) is a function of the difference in the temperature of the coolant and the ambient air. So most of us instinctively understand that the coolant will run hotter on a hot day than on a cold one. What many don't recognize is that as the coolant temperature rises, the difference between it and the ambient air increases allowing the cooling system to become more effective at removing that heat. So even on a hot day the coolant will only increase in temperature until the difference between it and ambient is sufficient to allow the cooling system to remove the necessary amount of heat. Unless there is a malfunction, the coolant temp will not continue to rise uncontrollably. It will simply rise until it reaches the new equilibrium temp.

Regarding the fan: Note that some sellers claim their fans are reversible by simply changing the polarity of the wires. In my experience, fans with curved blades are much more effective in one direction than the other. If your fan has curved blades, it likely works much better as a puller behind the radiator, than a pusher in front of it. And of course an effective shroud to direct air through the radiator is essential.

[Treeve]

Might be worth checking if you've got proper shrouding around the radiator so the air doesn't recirculate and that all the air going through the nosecone is actually going through the rad and not just going around the sides.
Treeve

[BITTEN]

Thanks everyone.
As it turns out we had a faulty terminated wire that failed while driving hence why it ran at 87-90 then rose to 110 without warning.
Glen, we started with a Crown chassis but only the front cross member is crown now.
Hand built 4 link bars, sway bars, wish bones, watts link,engine mounts, Carbon dash etc etc
I’ll post more pics soon

[incoming]

I never thought pusher fans made much sense. In the HVAC/R industry, you pull air through hot coils and push air through cold coils.

[BITTEN]

Yeah you’re right Incoming. Unfortunately we built the radiator frame toward the engine for better weight balance but didn’t leave quite enough room for a puller fan. The SPAL fan we have flows 3000cfm as a pusher when most pullers that are reversed as a pusher drop significant cfm (rated as pullers)

[eschaider]

Electric pumps frequently pump significantly less than their rated flow when pumping against even a moderate resistance (head). A 30/40/50 or more gpm pump may reduce to 30 gpm or even less when pumping against the head created by the reduction in hose ID represented by a T-Stat, hose plumbing or the coolant passages in a head gasket.

The best performing electric pump I have found (so far) is a Delta-Pag unit that I ran across at PRI a couple of years ago. It is a for real 60 gpm flow rate with a brushless variable speed motor that rises and falls in step with coolant temps. Click here for more info =>Delta-PAG Pump and go to page 4

[xb-60]

Originally Posted by BITTEN

.....Glen, we started with a Crown chassis but only the front cross member is crown now.
Hand built 4 link bars, sway bars, wish bones, watts link,engine mounts, Carbon dash etc etc
I’ll post more pics soon

Looking forward to the pictures.
That is some achievement, modifying/refining/designing a chassis and building a car as a team effort, actually getting sufficient consensus along the way to actually finish the project

Cheers!
Glen

[cycleguy55]

Originally Posted by BITTEN

Hi Team
Some of you might remember our cobra as BITTEN now BITES in custom orange paint. We may have upset a few by not sticking to originality but that’s our thing.
My Dad and brother and I have built BITES from scratch over the last 20 years.
She looks great and the 331 is unbelievable. I must admit that we probably went too aggressive with the Cam as it’s making power past 8,200rpm which robs torque but it’s a light car.
To my issue. She is on the road and handles amazing with the Penskes however she gets way too hot for my liking. Sits in the 90 degree C mostly but climbs to 110 (at that point I stop or get to open road and it drops to high 90’s or low 100’s).
I have just installed a brand new highest output SPAL thermo fan - no difference.
Removed the stupid accusump (doesn’t hold primed air pressure) to see if it was blocking air flow- no difference.
It has an electric water pump and was professionally tuned with a Link Xtreme ecu and a 3 core alloy radiator.

It is possible that the cam is retarded to a point that’s contributing but changing that is a major issue (engine out and retune).
Any help will be appreciated greatly

I'm curious as to why you believe 110°C is too hot.

My daily driver normally runs at 90°C, and can easily get to 110°C in hot weather with air conditioning running, working hard, etc. Edit: I believe the red part of the gauge (overheating) starts at 130°C / 266°F.

My BBF Cobra has been to 110°C (230°F) on a number of occasions without any problem. In fact it's been to 250°F / 121°C without any ill effect when the cooling fan relay failed - other than it puked a bit of coolant due to expansion.

What problems are you trying to avoid?

[Tom Kirkham]

Not having enough ignition timing at low RPM will cause overheating.
How much ignition advance do you have at idle?
Do you have a vacuum advance?

Side note...
late ignition and the rich fuel will make your headers glow...

[eschaider]

Originally Posted by Tom Kirkham

... late ignition and the rich fuel will make your headers glow...

And set fire to combustibles in close proximity. The good news is the fire is easy to detect from the smoke, heat and flame.

[jknich]

Manifold vacuum for distributor advance helps cooling at idle.

[Dominik]

In reference to "at that point I stop or get to open road", and also what Tom posted:
Are you overheating at low rpm?

My headers once started to glow red hot in seconds at idle. The static timing was only 6deg.
I went to 16deg (starter didn't like 20deg) - BUT retarded at WOT to remain at my comfortable 35deg total.

This is important!!

[BITTEN]

My tuner told me that 130 deg C is getting too hot for an old style block vs modern engines. Something definitely seemed odd to me when it normally runs in 80’s.
The air box was too hot to touch after an easy run around town and the collector blistered the body paint. I guess bottom line is that it is much hotter than normal (normal being before this tune which has a more retarded Cam and much more timing advance (side note it didn’t like anything less than 60 deg adv)).
Anyway turns out the 20 amp thermo fan fuse was under sized (should have been 30amp) and it was tripping. All sorted now and engine runs mid 80’s-92 deg C