Running too hot?

[72442conv]

My GTM usually runs from 215-225, which seems okay to me for what LS engines typically run in Corvettes, but I have always been concerned that it is too hot. On Thursday I got into a traffic jam, and it was a hot day in South Florida, so it started going to 230 and maybe even a bit over that. At 230 I started getting concerned about it, but thankfully after it hit a bit over 230 I was able to get onto the turnpike and temps went back down into the 220 range. I have no idea where the fans are coming on and off. This car has a 575HP LS2 crate engine that came from Texas Speed and it has their ECM, but I really do not know where they set their fans to come on and off. My understanding is that on a factory Corvette the primary fan does not turn on till 224 and the the secondary turns on at 238. Is this correct? Would Texas Speed leave that stock? I know these engine run hotter than most, but at what point are you really having an issue? Looked at a bunch of threads which talked about air being caught in the system, most of those cars just overheated, could there be a bit of air in the system?

[72442conv]

Found out something interesting today. Took the car to work, when I got there temp was at 220. I opened the hood and both fans were going at full blast. What was interesting is that with the hood open the temps stated to fall while the car was parked. I have read threads stating that there is not enough airflow out off the hood, and that cars that ran cool in the go kart stage would not do so when all the body was on. I can confirm that there is an issue with airflow out of the hood area. Not really sure what a solution would be on a completed car, but if you car is not completed, definitely look at making the hood openings bigger.

[VRaptor SpeedWorks, LLC]

That is why I made these....which can be installed on a finished car...

http://vraptorspeedworks.com/gen-ii-...-hood-louvers/

http://vraptorspeedworks.com/gen-ii-...engthmax-flow/

[beeman]

Are the fans fully shrouded? At speed if you are overheating, assuming the system is bled correctly, you are overheating because air doesn't want to go through your radiator. I see a lot of GTMs with inadequate ducting in front of the radiator that allows air to go above, left, right, or most commonly under the radiator. At speed, air does not want to pass through a radiator because it is relatively restrictive, it will choose any other path it can unless you force it through. My guess is you have huge pathways that the air can take around your radiator. This will also cause front end lift at speed if the air is going underneath the front of your car. Usually outflow is not an issue if you have more that 25% of the radiator surface area available for exit (unless you are trying to outflow to a high pressure area - not a problem with the GTM exit locations).

[VRaptor SpeedWorks, LLC]

I've experienced this enough times now to say there is a definite difference between the Gen I and Gen II. I don't recall any of the more than 20 Gen I GTM's that we've had thru the shop running any different temps with the hood on or hood off. With the Gen II's, we've seen this with about every single one we've built now. Temps are fine thru the whole build and as soon as you put a finished hood on the car and close it and drive the car, you end up with 220 degrees+ coolant temps.

[beeman]

Good point, Shane, I was thinking Gen1.

[72442conv]

This is a gen 2 car.

[72442conv]

Are the fans fully shrouded? At speed if you are overheating, assuming the system is bled correctly, you are overheating because air doesn't want to go through your radiator. I see a lot of GTMs with inadequate ducting in front of the radiator that allows air to go above, left, right, or most commonly under the radiator. At speed, air does not want to pass through a radiator because it is relatively restrictive, it will choose any other path it can unless you force it through. My guess is you have huge pathways that the air can take around your radiator. This will also cause front end lift at speed if the air is going underneath the front of your car. Usually outflow is not an issue if you have more that 25% of the radiator surface area available for exit (unless you are trying to outflow to a high pressure area - not a problem with the GTM exit locations).

Highway speeds are not really too much of an issue, 220 is normal and it can go down to 215 on cool days. Issue is really in traffic where it will go to 230 if you are not moving.

[72442conv]

That is why I made these....which can be installed on a finished car...

http://vraptorspeedworks.com/gen-ii-...-hood-louvers/

http://vraptorspeedworks.com/gen-ii-...engthmax-flow/

This car has quite a bit of your parts Shane, but it does not have the hood louvers. I have been thinking about it as I know you sell them, just not sure I will like them on there, LOL. I don't see many other solutions as trying to vent to the inner fenders probably will not work as that is a high pressure area, same as trying to vent to the back of the hood...

[VRaptor SpeedWorks, LLC]

I do understand that the look of the louvers isn't for everyone....but not sure what other solutions there are on a finished car without getting really time consuming and expensive.

[GTMsomeday]

On my car I lowered the shield in front of the radiator (with all the decals) and removed the shield at the windshield (center section only). Basically I vent to the back of the hood. This provides a good flow thru. Never runs hot. My car is a gen 1 though. But I modified the hood to make the opening more like a gt-40. Which has a smaller opening. Hope this helps! Maybe give you some ideas. Good Luck!

[Fraser D]

You can always try mesh with a larger opening to material ratio.
I am guessing but I think that the mesh FFR supplied is ~50/50.
McMaster Carr sell the same style in a bunch of different ratios

[72442conv]

This is a Gen 2 car is has the 8 small holes in the hood, no mesh. There just isn't enough area in those holes to vent the air being moved by the fans.

[Fraser D]

This is a Gen 2 car is has the 8 small holes in the hood, no mesh. There just isn't enough area in those holes to vent the air being moved by the fans.

Understood.
I have all radiator air flow vented in front of the wheels.
It has a different radiator set up than standard but I have not experienced any adverse handling issues at speed.
You could potentially go through the side panel without effecting the look of the car or costing big $'s.