[ponyboy96]

Just curious if others have experienced heat soaking and power loss of the track when it’s very hot out. I was running the car as hard as I could this weekend and noticed that I was definitely down on top end speed by about 20mph or so. I typically see high 140-150 on this straight, but could only manage about 130-135 this weekend.

Now it was very hot with track temps around 98 degrees. Only change to the car this time vs last, was I did add a rotofab intake (standard, not big gulp). So was the car just pulling that much timing that it was way down on power or is it possibly related to the intake. Car is stock with no tune.

If this is common, what are you guys doing to help with the heat on track?

[Spaceme1117]

Likely, your intake air temps were very high. Likely over 150F or more. So car will be pulling timing and have reduced power.

I can remember the exact number but I think on 4th gen LS motors (LS3, LS9, LS7, etc.) the ECM pulls timing when IAT's get to 125 or 130. Likely the same or similar for LT1, LT4.

May be time for some cooling mods for your car; bigger supercharger radiator, larger reservoir tank, etc.

On my C6 Corvette, I have an E-force supercharger. I added a larger intercooler radiator, much larger Cordes Performance reservoir, spacer plates and heat insulation between the supercharger and engine, and I upgraded the radiator to a DeWitts. All of this keeps my IAT's much lower than before and the temps recover much faster after a run.

[RUQWIKR]

Originally Posted by ponyboy96

Just curious if others have experienced heat soaking and power loss of the track when it’s very hot out. I was running the car as hard as I could this weekend and noticed that I was definitely down on top end speed by about 20mph or so. I typically see high 140-150 on this straight, but could only manage about 130-135 this weekend.

Now it was very hot with track temps around 98 degrees. Only change to the car this time vs last, was I did add a rotofab intake (standard, not big gulp). So was the car just pulling that much timing that it was way down on power or is it possibly related to the intake. Car is stock with no tune.

If this is common, what are you guys doing to help with the heat on track?

Heat soak, high oil temps, etc. will be much more of an issue quicker with you being an A10.

[Badmojo]

You can expect 5-7 mph drop on long straights in high ambients.

You can help reduce the impact by:
1. Katech 172 F thermostat
2. Reduce the glycol percentage in the radiator and intercooler
3. Add redline water wetter



Sent from my iPhone using Tapatalk Pro

[ponyboy96]

Thanks. I was doing some reading and went ahead and ordered the ADM reservoir kit. I’m thinking high heat and possibly some air in the intercooler or something. Probably a good start.

[Beescuz]

I was at VIR a couple weeks ago with Chin. Temp outside was around 90 degrees on Monday. Around the 30 minute mark car started pulling power on the back straight. Wouldn't go over 130mph. Oil temp was around 270 degrees as well.
Let the car cool down and had no more issues remaining of the day.

[20Bluezl1]

What was your coolant temp?

[Beescuz]

Originally Posted by 20Bluezl1

What was your coolant temp?

Mine was 190.

[Badmojo]

I would check this on the PDR with Cosworth toolbox or an OBD2 reader. The on-dash display is notoriously wrong.


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[Gunkk]

Originally Posted by ponyboy96

was definitely down on top end speed by about 20mph or so. I typically see high 140-150 on this straight, but could only manage about 130-135 this weekend.

Check and bleed the supercharger intercooler loop. Might have air pocket which will cavitate down the pump, triggering pump-safety-shutdown and raise AITs, causing the behavior you describe.

[20Bluezl1]

Originally Posted by Beescuz

Mine was 190.

Wow my temps are around 230⁰ I wonder if something is up with my coolant system. Maybe bad thermostat?

[Badmojo]

Originally Posted by 20Bluezl1

Wow my temps are around 230⁰ I wonder if something is up with my coolant system. Maybe bad thermostat?

220+ F is normal under track conditions per OBD2 gauge or the vehicle health tab in the Cosworth Toolbox. The factory dash gauge might as well be an on/off switch.

[ponyboy96]

Originally Posted by Gunkk

Check and bleed the supercharger intercooler loop. Might have air pocket which will cavitate down the pump, triggering pump-safety-shutdown and raise AITs, causing the behavior you describe.

Yes I added the reservoir which should fix that. After the install, it sucked down a good bit of coolant, so more than likely that was the issue. The car feels like it picked up a bunch of power post install.

[Mountain]

Originally Posted by ponyboy96

Just curious if others have experienced heat soaking and power loss of the track when it’s very hot out. I was running the car as hard as I could this weekend and noticed that I was definitely down on top end speed by about 20mph or so. I typically see high 140-150 on this straight, but could only manage about 130-135 this weekend.

Now it was very hot with track temps around 98 degrees. Only change to the car this time vs last, was I did add a rotofab intake (standard, not big gulp). So was the car just pulling that much timing that it was way down on power or is it possibly related to the intake. Car is stock with no tune.

If this is common, what are you guys doing to help with the heat on track?

Yep. See any discussion on this past [2021] SCCA TT Nationals at NCM.

Originally Posted by Badmojo

You can expect 5-7 mph drop on long straights in high ambients.

You can help reduce the impact by:
1. Katech 172 F thermostat
2. Reduce the glycol percentage in the radiator and intercooler
3. Add redline water wetter



Sent from my iPhone using Tapatalk Pro

Good recommendations. About the T-stat, even for an LT1, it is something to look at if you track a lot. The reason is for oil temperatures. Although the factory setup seems to stabilize, and not get too dangerously hot, it gets into a worrisome range (265-270F), and you better be running quality oil of a proper viscosity... The factory oil cooler works via fluid-to-fluid transfer, getting cooled by the oil cooler block attached to the engine block/oil filter block. This is cooled via the "cold-side" portion of the engine cooling system/radiator. If the coolant/fluid is not circulating, you wont get flow to provide more cooling (cooler coolant gets hot, and heat transfer slows down as it transfers into fluid father into the circuit, instead of getting more fresh, cooler fluid locally). The T-stat is your gate-keeper of that.

I don't have a lower temp T-stat yet, so I haven't data logged this, but I'm willing to bet there is something there. How much is the question, but if there is -10F, that's a worthy change! Oil temps of 155-165F are better than 165-170F.

Originally Posted by Gunkk

Check and bleed the supercharger intercooler loop. Might have air pocket which will cavitate down the pump, triggering pump-safety-shutdown and raise AITs, causing the behavior you describe.

Good call. Some ZL1 owners at this year's TT Nats did this and were able to grab a noticeable gain in power back.

Originally Posted by Badmojo

220+ F is normal under track conditions per OBD2 gauge or the vehicle health tab in the Cosworth Toolbox. The factory dash gauge might as well be an on/off switch.

In my SS 1LE, I've never seen my coolant go beyond 220F. In fact, 99.99999% time it wont eclipse 217F.