I just checked the manual and it doesnt give any info in regards to the crank pulley.

Its a generic installation manual...though it did say the kit shipped with 7,8,9,12, 15psi pulleys...

Is anyone out there running a p600b at 15psi?

 

I've never heard of anyone actually getting a full 15 pounds of boost out of a 600b. When I had mine, I ran 8 lbs. on a completely stock engine. Then, I had a tune and added ported LT1 heads, that's it. I dynoed 435 rwhp, 440 rwtq. Don't know the before numbers but even though the boost dropped down to 6 lbs., I could feel a significant increase in HP. I'd guess I picked up 30 HP. If you do the ported heads, keep an eye on the CR. If they open up the chambers, you may lose compression, which you may or may not want? For me, since I had stock pistons, I wanted the combustion chambers opened up to drop the CR.

 

I think I would have your stock castings ported first, see what gains you get and go from there.

 

Yea...I understand I will never see 15 lbs out of a 15 lb pulley but....What I was getting at is....If I see 10 lbs out of a 12lb pulley, a 15 lb pulley may give me 13 or so lbs? it could be good for 30 hp at the tires? and its just a pulley.heh..should be cheap etc.


I have read something about some dude in texas that people send their heads to? Was it lloyd elliot or...?

 

nighttrain66 on this site - Lloyd Elliott

 

You may have an issue with belt slip with the P600b and the small pulley.

 

i respectfully disagree.
in your scenario, the blower is pushing the air into the chamber, so the intake may not be as big of a deal , b ut the piston is the only thing pushing out the exhaust gases (unles you get a cam with a bit of overlap)
so if you crap a bunch of air into the chamber of an unported head, which do you think would get the exhaust out faster, a stock head or a ported head?

im not a fluid dynamics genius but i do know that you will pick up gains by getting a good porting job (i stress good)
i wouldnt be surprised to see 50hp at the same boost level.

realquick - your theory (calculation) is right imo, and im sure you did the math on a calculator.
i may use this to see if my blower is maxxed out.

 

Yea, I'll probably hold off on the pulley...If I were to get a d1, or other ati blower, would I really notice much in gains? vs the p600b?

The compression in the motor is around 9.2 to 1....and im running a 12psi pulley..not sure if I can run much more boost....

Do the new blowers make more boost lower in the powerband because of the impeller design etc? The p600b's impeller looks rather chinse heh..

These cars are a sickness...It was mothballed for a few yrs....now I'm contemplating dumping alot of money into it.....

Thanks for all of the input....I'll do the heads in the fall..when I take it off the road..

I have yet to get the car inspected...It had a temp inspection that ran out..

The reverse lights wont work....One valve cover is leaking some oil...Reverse pops out of gear....Needs brakes and an alignment... Then its ready..Small stuff really...

 

My experience with stock lt1 with p600b(8lbs) . !rst gear was useless 2nd was cool.

With Craig Gallant stage 2 heads, mild cam, voila!! 2nd gear was pretty useless. Lotta fun on the street with street setup. Very impressive burnouts!

Sorta boring now. Gotta have more. Good luck with yours.

eric t.

 

lots of bad information in this thread...

Boost that you measure is a result of air from the blower being restricted. Your cylinder heads only flow so much. The intake valve is usually the biggest restriction in any performance engine. Try to look at airflow along the lines of mass. You've got the blower squeezing a huge mass of air into the intake port. The port can only move so much at a time, so there is a restriction and the pressure that you read goes up. At the same time heat is building up from the crammed up pressurized mass of air.

Now open up the intake port or switch to larger aftermarket heads that flow better. The blower is still cramming the same mass of air into the port, but since the port flows better, there is less resistance and more air gets into the cylinder. Less resistance means less heat as well. Now there is lower temperature air mass easily flowing into the cylinder. You read lower boost pressure while making more power.

But there is more. Look at the exhaust side. An opened up exhaust port does wonders on a forced induction engine.

And like you mentioned, you have the ability to lower the compression ratio which lowers cylinder pressure a bit. You can change pulleys and increase pressure again starting the entire cycle over again.

Look at Top Fuel engines. They make around 8,000 horsepower with huge superchargers. Do you think they run unported heads?