Background: I'm running a Comptech S/Cer without A/C. (I did notice a droning sound that I'm pretty sure it wasn't there before coming from the intake lately, if it matters at all....)

We all know about the heat soak issue that our car has. My question is, does anyone have any solid numbers from testing or ideas of how bad the heat soak really is? Are we talking about 10% lost of power or even more?

Second, how long does the engine have to cool down for the issue to be gone,....other than overnight?

 

Hey man, I feel an amazing difference. I have tracked my car a few times now and I can tell you that my car DEFINITELY acts and responds differently during the first session as opposed to subsequent sessions. Why?

Because, the car is cool and warmed up during the driving of the first session. I feel I'm getting optimal power and response. Then, we take a cool down lap and head to the pits/prep area. There my car sits (hood up) heat soaking from the hard driving. My supercharger is not too hot when I first get back from a session because I have a vented hood and I've been driving 100mph, but the entire bay gets VERY hot once the car has been sitting still for a few minutes. For subsequent sessions, I definitely don't feel the same intial pull when accelerating out of pitlane but 1 minute of 100mph+ driving seems to cure the hiccups our car gets when it's heat soaked. Then, the car feels great again and I go through this cycle. I have been trying to figure out how to cure this and I really can't think of a solution. I imagine even the best race-prepped cars of any manufacturer have this problem.

You asked for numbers, this isn't ideal because I have always had my supercharger but it might give you an idea of how much air/intake temperature can make a difference. First, my car's dyno have literally varied from 286whp to 260whp without any modifications (just updating tunes for weather). I dyno'd 260whp in the worst of conditions. It was approaching 100 degrees, humid, and sucky at Inline Pro in the summer. I live in the DC area and I'll be getting dyno'd later this month, again. I'll bet money my car puts down at least 20 whp this time of year. In fact, it feels completely different. It pulls stronger and reacts to the throttle inputs much faster.

To make a long story short, if you are drag racing your car or just doing the occasional pull on the street I think the additional boost is more beneficial than the lost boost but lower intake temps using an aftercooler. Drag racing is all about maximum HP over a short blast. If you are tracking your car I really think an aftercooler is beneficial. They hold quite a bit of fluid and I think they make a big difference when your moving. As far as HEAT SOAK, I don't think there's ANY solution other than to keep air flowing by moving. A vented hood might help a bit.

I hope this helps some. This is the end of my novel.

GL!

J

 

Yeah, I was curious if anyone had some numbers to show the decline due to heat soak. Personally, I had my car dyno'ed the moment i had my supercharger installed, and that was a cold engine. Then I had another dyno couple months down the road, but I've been driving the car on and off that entire day before the dyno.

Althought the dynos is couple months apart, and taken its 2 different dyno machine, I wouldn't think the base for this comparison would vary too much. From my numbers, i between a cold engine and a hot engine, t showed around 40-45whp lost. That's about 15%.

I was just trying to verify with other "S/C w/o A/c" owners out there.

 

No one has ever done/thought of this?

 

Look for some of xvipers old posts...he did some testing with thermocouples and posted the data along with some tricks to keep engine bay temps down.

Quite a few of the owners here in Florida have cut their hoods...look for DYI hood vent.

 

I have taken your information and looked into the posts that xviper did awhile back that dealt with engine bay temperature. The post is very informative about the rise and fall on engine temperautre during driving. I've ran across numerous methods to help heat soak

What I'm more interested in, is the number in terms of hp lose. I have looked high and low for some numbers and didn't find any. I have a rough ideal on that hp lose since I did a few dynos, but in different conditions and different time of the year.

In a few days, I will be doing some more dyno and post up some solid numbers in terms of hp lost due to heat soak.