I bought a p1sc 8lb kit. I have a few of questions that aren't a big deal but I probably should have asked already.

1: Are there slippage problems with the pullies in the kit?
2: When running ported heads I was told I would lose boost. Is this true? How much?
3: Is this rating on the money or is it under rated like a vortec?
4: Are there any comon installation problems with this kit?
5: Are there any tuning issues with this kit?

Any one that could answer any of these questions would be a huge help.

 

lets see
1. Luckily we have a spring tensioner whichc really reduces the amount of slippage. So as long as you have it PFT it shouldn't slip
2. You will loose boost with ported heads. How much depends on your port job. I have a 10 lbs kit with LE3 heads and I peak out at 8.5 lbs.
3. not sure about the rating havent done the math
4.one common installation problem...its a PITA. Ls1s are so much easier.
5. I had mine tuned by Jeff Creech and he didnt seem to have any problems other than running out of fuel quick

 

I'll be running le1 heads that flow 270/190. I guess i wouldn't lose as much boost as you. Maybe none at all. Thanks a lot for all of the answers.

 

loosing boose = good

 

I have a 12 psi ati pulley and I only get 9psi at 6000rpm. I don't have any belt slippage with my 8 rib. Yes tuning is hard but I'm a novice tuner. It is best to get a professional dyno tune. Make sure you get a fuel pressure guage and a boost guage so you can keep an eye on your motor before you start romping on it.

 

aggiez28: loosing boose = good


Loosing BOOS(Z)E=Bad, especially on the weekend... BUT, a reduction in boost due to better flowing heads should = an increase in power. After I installed my re-worked heads, the SOTP increase in power was significant.

 

I wish that more enthusiasts understood the boost/airflow relationship as you all. When you purchase a kit and the manufactuer claims a certain boost level in literature it is based on a stone stock combo. When we "spec" a boost level for a modified car we make generalizations about how certain modifications affect volumetric efficiency. A better breathing engine will inhale and expel more air and less will back up in the intake, thus lowering observed boost on a gauge. This will result in increased power on multiple levels.

First the cylinder charge will be denser and allow you to burn more fuel.

Second the charge temp will be lower as the pressure isn't as high, increasing density.

Third the blower will be working easier which results in less parasitic loss.

Fourth you can choose to turn the blower up again and run more boost (airflow) on pump gas which while negating some of the above gains will result in even more power.

A supercharger produces airflow. Excess airflow above atmospheric pressure produces what we call boost. The amount of boost observed on the gauge is dependant on the volumetric efficiency of the supercharged engine.

For example, lets suppose your blower is capable of delivering 950 cfm at your rpm/pulley ratio combination.

Lets say you have an LT4 350 and you rev it 6000 rpm. A stock LT4 has a VE% of about 85%.

((350 x 6000) / 3456) = 607 cfm (100% VE) * .85 = 516 cfm

Now let's see roughly how much boost we can make:

950 (blower) / 516 (stock LT4) = 1.84 x 14.7 (atmospheric press @ sea level) = 27 psi absolute. 27 - 14.7 = 12.3 psi of boost. This is simplified and ignoring temp and friction vaiables.

Now lets add a set of ported heads, optimized cam and a good exhaust. VE% could now increase to 95% or better. Let's figure 95%.

607 x .95 = 577 cfm
950 / 577 = 1.65 x 14.7 = 24 psi absolute - 14.7 atmospheric = 9.3 psi.

Which engine do you think will make more power?

Okay now let's spin the blower back up to make 12 psi again. How much additional airflow can we get and still run on the gas we ran before the upgrades?

577 / 14.7 psi = 39.25 cfm per psi

39.25 * (14.7 + 12) = 1047 cfm

This is a 10% increase in airflow

It takes roughly 1.5 cfm to make 1 hp so the theoretical potential is 698 hp. The actual gains will be a bit lower due to temperature, friction and parasitic losses but it can be remarkably close to this number at that boost level.

For instance a stock LS2 can easily make 500 rwhp on 7 psi of intercooled boost. This would suggest flywheel hp around 575-590. Imagine if the compression were a point or so lower where it could be bumped up to 12....

 

Yeah, I understand that less boost isn't nessecarily(sp?) loosing power on ported heads. After all that would increase the motors airflow potential right? Which as markinkc69z stated would make the combo more efficent. When I started reading his post i was taken back but then I saw he was a ati tech. Then it all made sense that he could just throw out those numbers. Are there any other gauges i should get? Say a A/F gauge? Or is that overdoing it? Thanks a lot guys. I can't wait to get it a put it together.

 

I really reccomend the Innovate wide band line. It can be invaluable for tuning and optimizing your setup. A fuel pressure gauge is also very useful.