Cruising IAT's (Whipple Gen5)

[Angrey]

So I've been empirically collecting data on my drives.

I have a Whipple Gen5, 2.75" pulley, Oversized Heat Exchanger and a Trackspec hood vent. I have a wonderful .50 final overdrive paired with 4.09's so my cruising speed at 2k rpms is 77 mph.

My IAT's are most optimal at around 85 mph. At that speed, the airflow is significant enough to drive heat out and the engine load is still low enough not to create significant heat. At 85, I'm generally 10 degrees above Ambient (although I've seen it momentarily dip to 8 or 9 degrees, but steady state would be about 10F over ambient).

If I slow down to say 70, although the engine load is slightly less, the air flow is less, so the over ambient climbs to about 12 degrees. If I speed up and cruise at 90-95, the airflow is greater, but the engine is working harder and so it climbs from 10 over to about 12 over.

I was just curious to see what others are getting for IAT2's over ambient when cruising.

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[engineermike]

I’ve found that airflow through the engine affects it more than airflow over the LTR.

 

[Angrey]

I’ve found that airflow through the engine affects it more than airflow over the LTR.

I found it interesting that there's an optimal dip. At first I was a bit concerned/dismayed because I'd get double digits over at lower speeds and it would decrease with speed/airflow, but then it would increase again at higher speeds. Seems there's an optimal tradeoff between how much heat the motor is creating to maintain speed and how much airflow it's receiving at that particular speed. All of these are of course steady state/full operating temp. It takes the car awhile to warm the exchanger fluid fully.

I think the hood vent is making a huge difference. But I have no before/after to confirm that.

Forgot to add I'm running the whipple "closed" style box/divider around the filter, but admittedly it could be improved to fully isolate from the engine bay.

 

[engineermike]

One interesting thing I had happen was when idling, I logged IAT actually higher than MCT. This means the intercooler was actually cooling the air at a standstill even with no air passing over the LTR. Even with the small LTR it seems the water system has a lot of heat capacitance.

 

[Angrey]

One interesting thing I had happen was when idling, I logged IAT actually higher than MCT. This means the intercooler was actually cooling the air at a standstill even with no air passing over the LTR. Even with the small LTR it seems the water system has a lot of heat capacitance.

It's one of the reasons that I preach about relying on dyno sessions for determining things like how much a motor can or can't handle, etc.

When we did my dyno rips, IAT's were wonderful because the car hadn't fully heated up all the coolant in the exchanger. Out in the real world, the car is heat saturated and that latent capacity is gone.

 

[S550AC11]

In the summer I'm +20ish on the highway at 70+, +30 in town. It will climb higher if I sit idle for extended time but come down quickly once I get moving. In the winter I've been as low as +7 on the highway and +18-20 in town.

I have the standard heat exhchanger with an RTR grille which feeds my air box and exchanger. 3.875 pulley. In roll race scenarios I've never had temps climb above +30.

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