Hi Forum,

I have fitted a ProCharger P1SC kit to my stock 2008 Corvette LS3 vehicle. The kit came with a 4.63 pulley.

Initial tests on dyno showed a engine power level of only 515 hp and a boost of only 4 psi.

I then replaced the scrappy stock blow off valve with a quality piece from Forge and then complete leakage tested the hole system up to over 50 PSI.

No leakage and no belt slip.

Did a second dyno test with just about the same boost.

Then I saw on different forums that indications that maybe ProCharger have fitted the incorrect impeller. Some threads stated that this had happened before.

ProCharger claimed that the kit had the right impeller but I am still unsure.


I have counter clockwise rotation on the impeller. I looked for a upload function for a picture without luck so I just have to describe the impeller. Looking at the impeller, from the front of the car, on the fins that are located around 6 a clock. The fins are bent towards the right side i.e. they don't seem to shovel air with a clockwise rotation but if you imagine a counter clockwise rotation they should shovel air..

Questions:

a) Should a stock ProCharger kit with a 4.63 pulley give around 6 psi and deliver roundabout the promised 600 + hp?

b) Or is the ProCharger marketing promises made for a smaller pulley?

c) Any other idea on what could be the problem?
The tune have been checked by an experienced tuner. The vehicle runs very rich at high revs (10:1) so fuel supply is not an issue.

I don't want to change pulley and belt only to find out that they delivered me the wrong impeller...

Thanks for any assistance!

 

I think your questions could only be answered by ProCharger, contact them.

 

I doubt it's the wrong impeller. What else is done to your car?

 

First of all nothing else is done to the car. Its completely stock.
I have had discussions with ProCharger who recommends a 4.38 Pulley to get the boost where it should be.

In their marketing material they announce 6PSI and a level around 620+ hp so I wanted to see if someone else had a similar experience like mine or if others got boost and powers as advertised.

I live just some meters over the sea level and the temperature here is 15-20 centigrade which is like a normal spring day so it cannot be weather related as this was one possible explanation from their side.

If others get 6PSI with the same pulley like min then something must be wrong with my compressor unit. If others get the stats with a 4.38 pulley at least the fix will be easy.

 

That 620 number you speak of is crank horsepower not horsepower at the wheels. Wheel horsepower is lower because you have to factor in drivetrain loss. Is your car auto or manual? Either way 515rwhp at 4psi sounds about right for a stock LS3.

 

you SURE your belt it tight enough? I had to do some work and tightened mine to where i THOUGHT would be fine... but it wasnt giving me full boost... I had to REALLY crank down on it to get my boost back to where it should be.

 

@Detoxx03. My 515 is also at the crank so a bit disappointing considering the stock 436..
I don't doubt that 515 corresponds well to 4PSI. My problem is that the kit should deliver 6 PSI. The tune I use if for 6 PSI so the car runs stinking rich now with the low boost.
@Robertaj. Well what can I say. The belt is very tight. No slipping sound detectable on the two dyno runs I have done so far, Not a squeak...No friction heat detectable on the belt after the dyno run either. I cannot see that this is where the problem lies.

 

Ok had no idea that was at the crank also. I would try the pulley swap just to see. Maybe they sent the wrong pulley or expected the car to have more mods.

 

So this is on an engine dyno?

 

@Carlos: I have had it to the dyno twice.
First time we suspected leakage and then I changed the scrappy stock bypass valve to a forge high-end one. We then also ripped down the plumbing and replace all clamps to T-clams and then pressure tested the whole piping.
Very small leakage at 6 BAR which is over 70 PSI so the plumbing is ok.
Then back to the dyno with the same disappointing result the second time...:-(

 

Dyno?

Unless you are pulling the engine every time you dyno you are NOT getting flywheel HP.

Flywheel HP stock is 436HP, that works out to around 370 on a drive wheel dyno. Your 515HP on the Dyno would be around 565HP at the flywheel. Depending on the make of the dyno, the operator and the conditions of the run the engine could make 615HP on a different Dyno with a different operator on a different day.

 

He said his 515 was at the crank so his numbers at the wheels would be upper 400's.

 

Guys, at the dyno they of course measure at the wheels but they also have an algorithm to calculate the crank hp. That is how they get the crank hp.
The problem remains there as the vehicle is not generating the boost it should for the tune it has. (Too much fuel at WOT, 10:1) I need more air, hence I need more boost to make this work :-)

 

If your car is a stock automatic, 515 rwhp with a 4.63 pulley is about what you should expect. Go down to around a 4.0 pulley and you should get about 550-560 rwhp. That is what I experienced.

 

No offense, but if you're at 10:1, your car needs to be tuned. Stop whining about boost numbers and get a tune. Also, post wheel numbers. Crank numbers are for magazine-gawkers.
If you can't figure this out yourself, go to a shop.

 

Some questions,

What RWHP is the car at now?

How much timing?

You say the fueling is 10:1 which could mean a lot lower than that since most widebands bottom out there. That will cost quite a bit of power.

 

There seems to be a lot of questions here...to me.

I initially asked for references from others which have fitted a P1SC ProCharger kit to a stock LS3 vehicle, for a certain pulley. In my case 4.63.
The no 1 problem is that the boost is not what it should be as it should be around 6 PSI.
(According both ProCharger as well as according to the tuner)
Of course the tune is incorrect for the current boost but it is not the tune that is the problem it is the lack of boost.
With the right amount of boost i.e. air, the air fuel ratio would be fine.
The question is just if I need a smaller pulley(reference data from others please) or if I have some problem with the actual compressor unit.

 

Go look at your impeller, versus that of other corvettes. That will solve that.
Next, look at the setups of other, identical corvettes. Are they making 6lbs? Or is it less?
Third, is there dust around the belt drive?

 

You're too hung up on the boost number.