The hose from the aftercooler goes to an additional front mount heat exchanger... probably mounted in front of the radiator. YS is using a B&M tranny cooler with a fan for his front mount heat exchanger.

 

Update

The car originally had a 4.25" pulley made by Durham Performace. Without the aftercooler we were getting about 7.2 PSI of boost at the intake. With the aftercooler installed, this dropped to 5.6 PSI.

Today we installed a 3.875" pulley made by ASP. We are now at 6.5 PSI.

I am not sure if there is a difference specs between the way Durham Performance makes pulleys and the way ASP does, but I was expecting a larger gain in boost. I can't really explain why there wouldn't be a larger gain.

At this point, I have 2 options:

1. Get a smaller pulley to achive more boost and then tune. Depending on the pulley size, we should be able to get around 300+ RWHP.

2. Tune as is. As is, we should be able to get in the 290s for RWHP.

Thoughts, suggestions, opinions??

-YS

 

I'd up the boost at least back to where you were. I think it is the aggressive turn into the intercooler that is killing your boost at the moment altough a 1.6psi drop isn't really bad. My 12psi supercharged Miata only looses about 1psi through the larger intercooler so I would expect a max of about 1psi through the 4X6". As long as you are staying in the efficiency curve of the blower and the rest of your system can handle it, I'd turn the boost up. The intercooler will keep your temps down and allow you to still run aggressive timing even at the higher boost level. FYI, I don't know what the pulleys cost you but I have them made locally for my blower for about $50. I'm sure they could do them for you as well if you are paying more. Shoot me an email if you want me to look into that for you.

 

[QUOTE]Originally posted by samdog
[B]I'd up the boost at least back to where you were.

 

I thought you were dynoing today, YS?

 

We did 2 pulls to determine what kind of boost we are seeing. I am going to wait until Monday to actually tune so that I can decide if I want to try and up the boost just a little bit more before tuning. The post up a few levels covers what we saw for boost.

-YS

 

At this point... someone *cough cough cough* is recommending a smaller pulley...

 

If you're setup to handle it (fuel delivery wise), why not run more boost than your previous 7.2 psi? An intercooled 9 psi is going to have a cooler intake temp than the non-intercooled 7.2 psi you were running. You'll be less likely to encounter detonation assuming your fuel delivery can keep up with your increased air density.

 

Right now were are trying to figure out how boost the 3.875" pulley should be producing. Until we know that and whether or not the drop in the aftercooler is constant, we would be really guessing on what size pulley to use. My main goal with the aftercooler was to make consistent power when racing in the warm months. If I can run the same HP as I had before over a wider ranges of ambient temps, I would be very happy.

-YS

 

Update

I went with a little bit smaller pulley today - 3.675" pulley from Durham Performance. We are now pushing about 7.5 PSI at the intake which is just a shade under where I was. We noticed a little bit of belt slip in the top, so we are going to go with a 1/2" shorter belt tomorrow to ensure that doesn't happen. The peak boost may end up being the same, but we will no longer see the little dip just before peak boost.

The current HP output is 296 with 184 lb/ft of torque. We may be able to eek out a few more HP with the new belt, but probably not too much.

We measured temps before the aftercooler and after. It is 141 going in and 74 coming out at 64 degrees ambient. I am very pleased with the temp drop and I think that making a tad more HP than before with the cooler AITs will be much safer for the motor. We left the top end at 12.5:1 as there was only a 1-2 HP difference over 13.4:1. We decided to stick on the side of safety for a few HP.

Overall I am very pleased with the results.

-YS