My car apparently hates the dyno...the last 2 times, something has gone wrong to prevent us from dialing in the tuning. The first was a slipping tranny, replaced that and headed back this past Saturday. Now it's only making 3psi of boost with the 7" pulley...should be 9-10psi.

We were lucky enough to locate a new belt and diverter valve locally and replaced them with the car still on the dyno, but neither of them solved the problem. We already tested for blowby (none), tried it without the airfilter, and checked the clamps/hoses. All of my ducting is solid tubing, so it's not collapsing, and we don't hear any noticable air escaping.

Any suggestions on things to check, before yanking the blower and having Vortech check it out?

 

What kind of combo was the pulley rated for? Your motor, or a standard LT1?

Also I know you changed the belt, but is it possible it is still slipping?

Is your bov leaking?

How does the motor run off boost?

 

Thanks for the reply...we're not 100% positive the belt isn't slipping some, but I don't believe it is. Already replaced the "BOV"...that's what I referred to as the diverter valve, mine is routed back into the inlet. Car runs fine on and off the boost, just isn't putting down the power it should be. Up to 3psi it runs great, then flattens out....doesn't have the midrange punch it's supposed to either.

I think my Aftercooler has gone south...last night I put the stock ducting back on, which routes the blower outlet directly to the throttle body and saw about 8psi...it's tough to watch the gauge and drive. Of course all the clamps and tubing were messed with, so I'm planning to put it back on tonight after tapping the inlet for a boost gauge connection and see what happens. I couldn't see any obstructions in it, but I'll check it out more tonight with a mirror.

My Aftercooler was powdercoated and the shop that did it expressed concern that the hot oven would damage it, but I called Vortech from the shop and they said it would be fine. It better not turn out to be that...

 

So, do you think the aftercooler may be blocked somewhat, or leaking? Are you going to gage it before or after the cooler? You could definately see what was happening if you got readings on both sides of it.

 

I'm guessing it's blocked (we didn't hear/feel anything leaking), but I'm at a loss as to how that could happen. I get 8+psi with it bypassed, but only 3psi with it in the loop. I'm planning to look at it tonight, then tap my inlet for a boost gauge fitting so I can get both in/out numbers.

I do run my "backwards" from the typical Vortech installation...anyone ever heard of that causing a problem??

 

i see that your induction piping is routed differently but that doesnt matter. there is no difference, you can flip the aftercooler all day long and you will never see the difference. what im saying is that there is no top or bottom to it. so there is no inlet/outlet side.

what were your dyno numbers anyway?

i know with the stock pulleys on a stock motor vortech says that you will loose around 1psi with the aftercooler.

how much did it show previously? what have you changed with the motor. if you have done anything to your motor to make it flow better (like bigger heads), then you will have reduced your psi reading, while flowing a more air through it.

psi is the resistance of your motor to the forced air of the SC. same force form the SC / less resistance from the motor = less boost

if your motor flows better, then youll have to really up the superchargers CFM to bring back the psi reading....

ALSO, contact for vortech and check but, im almost positive that the more air you flow through the aftercooler the more restriction it will cause. if your flowing a lot you may need to step up to a large intercooler....

depending on what motorwork you have done you may need to upgrade your SC.

did you recently upgrade to a T-trim?

jeremy.

 

There were no changes to the motor. The first time on the dyno, it made just over 500rwhp (no nitrous) and we discovered the tranny was slipping. I put a new tranny in it and it was running like a beast on the street. This past weekend we tried to re-dyno and the first pull netted 380'ish horsepower, so we knew something was wrong. We tried again (with the same result) and noticed the boost gauge only reading 3psi and the car feels sluggish.

With the Aftercooler bypassed by using the stock Vortech tubing directly from supercharger outlet to the throttle body, my boost gauge once again shows 8+psi and the car is very responsive and pulls hard throughout the RPM range.

Does anyone have an Aftercooler that is not installed? If so, do me a favor and shine a flashlight in it...can you see ANY light on the other side? I can't see any on mine, but using a mirror inside everything I can see looks normal. The plates may be offset so I don't know if any light would normally shine through.

After I get everything hooked back up this weekend and a pressure gauge on each side of the Aftercooler, I'll know more. At the moment it appears to be my restriction and has changed for some unknown reason??

 

that is weird. did you recently change to the 7" pulley?

sorry ive never shined a light through it so i couldnt say. i would think you would see the light though.

there isnt anyway that the fins could have been damaged?

 

Nope, it had the 7" pulley on it the last dyno. I have a local buddy with one, we'll try looking at his this weekend. I can use a mirror and see both outside edges of the cooling "brick", and it looks fine. I'm assuming there's several rows of fins and they're offset from each other and maybe that's why the light doesn't show. It's all very strange...

After I get some hard data I'll give Vortech a call and see what they say...

 

well if nothing has been changed and you are all of the sudden loosing 5psi of boost, then something has changed somewhere.....goodluck. keep us updated