BIGBOS

I was seeing 9psi before on my 7.85" crank pulley (8 rib) and my 3.6" 8 rib blower pulley....

Now I went to a smaller 3.3" 8 rib blower pulley....and I'm only getting 10psi...


They haven't put the car on the dyno yet, cause they know I want to see about 12psi out of the car, I think it needs to get there to start making the power.....

But should I tune it as is right now and see how it does at the track, then make my next decision, or should I guess into the wind and order a smaller blower pulley, but I think if I go smaller then I will slip, even with the 8rib...

RyanJ

how high are you spinning the blower now? if you wanna swap pullies again...id get a larger crank pulley.

scottywheels

ryan the thing is that dropping .3 on the blower pulley is about 4-6 psi. so I think he is leaking somewhere. I run a 4.5 blower pulley and 8.5 inch crank...

RyanJ

really!? i didnt figure that much with good heads and a cam and all that. id listen to scott and take it to speedinc.

BIGBOS

Yea, they are going to work on it and see if they can figure out what the deal is...

BIGBOS

The car checked out ok, there were no boost leaks anywhere, and the BOV was tightened up a little..

I'm not sure what to do from here...

CHRISPY

dyno it and give it a quick tune you might be surprised

Then launch off the brake and **** yourself hehe

scottywheels

id run it like it is for a bit Brian. I stil cant see it only gaining 1 psi that doesnt compute. are you maxing the blower, 7.85 crank and 3.3 blower pulley.

Think of it this way, im only making 14 psi and Im a 346 so I know you will be happy with the car at 10 psi

NoGo

iTrader: (2)

I agree with Scott. I just threw some numbers together, and you really should be seeing close to 12-13 psi if you are actually spinning the blower that high.

Slippage? Maxing intercoolers? Restriction in the intake / suction side of the blower?

GMC SKI

what air filter are you running with this setup
If the engine bay is clean pull the air filter off for a run and see what happens
Are you running stock Ati intercoolers?

1dirtyZ

iTrader: (1)

check to see what your impeller speed is. if you reach it or exceed it you will actually loose boost.

scottywheels

I took my filter off my car and actually made an aditional 4 psi

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The car still has the supplied Procharger plastic intake ducting and conical air filter.

We can make a run without it, but if it worked I'm not sure what the long term solution would be.

JimmyKash

2 things:

1) check the intake tube to the blower...it might be collapsing and creating a restriction

2) check the connection to the throttle body, sometimes that likes to collapse as well and cause a restriction

BIGBOS

Well my friend an I did a calculation..

The max impeller speed of the D-1SC is 62,000

I have a 7.85" crank, divide that by the blower pulley which is 3.3", then you multiply by 4.10 because thats the ratio of the blower, and you get a #, then I multiplyed that by what RPM the car would be spinning too, I figure 6500, so it turned out to be 63,000 something, which is over the max of the blower, so it looks like I'm maxing it out, what should I do from here..

And F1 head unti is quite expensive, and only gives you 8000 more rpms of impeller max speed...

But the car will be getting tuned tomorrow as is, and I will take it like that for now until I decide what I will do next...

ChrisB

1000 rpm of overspinning the blower isn't a big deal at all. You won't really loose boost initially - you still may make more - but it will be more from heating up the air than from moving that much more additional mass (of air).

What camshaft are you running - you could be blowing out a good bit of boost - as realistically a D1 maxxed out should be good for 700rwhp with an optimized setup.

I would definitely try a run with the intake tubing removed to see what happens.

Also are you sure you aren't getting any belt slippage? You might try marking a pulley and your belt and seeing how far the marks are off after a pull.

Finally if everything else checks out I would pull the blower and inspect the impeller blades to make sure they aren't damaged.

CHRISPY

I would think you are having a restriction on the intake side of the blower.

Remove all the intake tubing and see what happens (on the dyno of course)

might need a solid intank tube and bigger K&N.

1dirtyZ

iTrader: (1)

the F! flows alot more CFM than the D1sc, so that should make a difference . i think you will make more boost at lower RPM.

BIGBOS

Well a new problem has come up...

My 42.5LB injectors are maxed out, they did pull off the the K&N and the boost shot up about 2psi...

GMC SKI

get the Siemans 55lb injectors they are a nice injector
that's what I'll be going with in my setup which is almost the same as your bit different cam though 224"/230" .587"/.593" 114LSA
Racetronix has them in stock
they should support the new power
I thought it might be the stock intake setup and K@n filter supplied
11 psi and a small shot of the giggle gas and your in business

jim