Hey Guys, Maybe some of you could help me troubleshoot my trackday power loss problem. I notice that my first 1-2 laps on the track are full power... car feels very fast. Then over the 2nd-3rd lap my power drops 20-25%. Do I have heat issues? should I upgrade my intercooler, upper/lower pipe, ignition system, jet hot coat the turbo components / manifold? I'm sure some of you road race guys have come accross this issue. I could sink alot of $$ and not know if one thing or the other could fix it.

BTW water temps stay perfect the entire time and never rise.

Thanks...

 

I used to own a turbo GTI and after some spirited driving in warm weather, it would heat soak like no tomorrow due to the weenie stock intercooler.

I see u aren't in stock boost so I would say your car might suffer from heat soak. Aren't NJ pretty cool at this time of year though?

 

You might try looking look to your oil temps - over a 20 or 30 minute session it was not uncommon for me to see my oil tems (Mitsu option oil guage & drain plug temp sender) climb quite a bit. I usually pulled the car off when my oil tems reached about 110c. My water temps never moved and stayed center guage.

Ambient temp could also be part of the issue - a combination of extreme engine heat and hot outside temps might be pushing your car towards a more conservative set of engine management parameters. Depending on how your car is configured that could be driven by either your ECU or your XEDE. If it's ECU or XEDE related you should be able to do some data logging to find the problem.

 

With the stock intercooler the car will heat soak a little after a few laps. I generally put in a few gallons of 100 along with some 92 to overcome the heat soak issue. Or you could just buy an intercooler, which will keep the IATs down.

 

So a new big intercooler should be the first thing to try?

 

Or some higher octane fuel... I'd try the cheapest solutions first...

 

It doesn't only happen on the track. if you get stuck in the traffic on hot summer day, the same happens... when you are going up hills for a while, when you load too much weight ( like 4 passengers) ...etc. I actually logged timing when this happened. it pulled like as much as -4 degrees with rich mixture. I think your car gets heat soak and start knocking (rasing the in-cylinder temp = detonation). Then, ECU will try to block anymore knock activity, therefore, you will be like 30~50WHP slower! if you have the after market cone type filter without heat shield it will get even worse.

Edit: many things you can do: use one step colder spark plug bpr8ES or even bpr9es for the track day. high octane gas, water/akly injection, big intercooler, low boost, bigger oil cooler, cold air intake box if you have the after market one.

 

I use 5 gal 100 and 5 gal 93 on the track. I think I have enough octane for the track.

 

FMIC it is, then.

 

Not precisely a "big" intercooler, but an intercooler has efficient flow for the power level you are running with minimal drop in boost pressure. A "big" intercooler tends to lose some boost presure than the stock one since it was designed for different hp application.

 

Um, no.

If you are running a stock BOV, I would replace it first. I found my spring would allow boost to blow off once it got hot. It would hold full boost for the first 2 or 3 laps, then it would start dropping off. First, 16.5, and then after 25 min, the car wouldn't boost over 14psi. i replaced the BOV with a Greddy RS, and now, the car is as fast on the first lap as the last.

According to the tests I have done on the dyno to look for power loss, making back to back pulls, there is little power loss *10%>x* with the stock intercooler running less than 19psi. Now, once you start boosting over 21-22psi, which was @360whp, the heat soak exceeded 10%, but was still less than 12%.

Hope this helps.......

The Freak.

 

I'm running 21 PSI with my tune from Shiv. Can I buy a spring for my type-s BOV?

 

Yes, you should be able too. I think they make a double spring mod. With my RS, I was boosting 23-24 (max) trying to get the limit of the valve.

 

What about pushing the little water spray button on the console to spray the intercooler?

 

Unless you removed a spring doing a modification as said to "reduce flutter" or whatever everyone seems to think is so good for Greddy Type S's, leave it alone and crank it down further. The Type S isn't affected by heat.

100 octane isn't enough, IMO for turbocharged cars. Unless, you're trying to save a catalytic converter. I run 112 leaded. It kills O2 sensors like no tomorrow when you're driving hard, but personally, I'd rather replace O2 sensors than rings/pistons/engines.

The factory gauge is too heavily weighted to really get anything decent out of it. Unless you're logging, have an aftermarket that little Mitsu gauge will stay in the middle until you're completely boiling over/hitting air pockets in the coolant/etc.

Have you modified the thermostat at all? I run three small holes in a 180°F/90°C thermostat. If you're too scared to mod the thermostat, go buy a lower temp thermostat. They're too expensive for me for what I can do with a power drill and something from AutoZone.

Oil temps really love to rise up quite high when you're running extended road course. EVO's have the benefit of vented hoods, a more upright/open fascia, and an oil cooler that comes stock. If you're really worried, get some aftermarket temp gauges.