I had done some research (posts on here & phoned Procharger) and was going to get the D1sc in order to have the capacity in the future if I build another motor. Right now it is an '89 IROC,stock bottom end,40,000 miles. Talked to the dealer today and he recommended the P1 would be a better choice for the street. It is mainly a street car, go to the track just for fun as well. He was saying the P1 would have better driveability as it has a more linear power band/flow. The D1 would come on more at a higher rpm (approx 3500), but lag somewhat at lower rpm compared to the P1. I was planning on building a bigger, better motor sometime down the road...but in reality,that may or may not happen. I am now leaning towards the P1 with the 3-core intercooler upgrade for now. If I eventually do build another motor, well...just have to deal with it at that time, maybe sell it & get a D1 then. For now, the P1 and D1 at 8-9lbs of boost would make basically the same power, just the P1 would give me better all around driveability.

Any thoughts on this would be welcome.....as I am ordering it probably tomorrow!

 

im running a d1sc with 10lb of boost on a completely stock L98 with no problems...just upgraded the injectors to 24lb .....

 

go with the d1.......to up grade later, the p1 will be 1500 bucks ..........10 psi with a d1 is a walk in the park with plenty left for future mods.

 

what kinda rwhp you guys seeing with the D1 at 10psi?

 

What about the driveability with the D1? I was told that due to the helix impeller in the D1 (vs. the straight impeller in the P1) that the boost does not come on much until higher in the RPM (approx 3500 area) Then it really comes on. At lower RPM, he was saying the D1 might feel like not much is happening, maybe a bit boggy (so to speak) I have a 2800 rpm stall converter in mine which may help that. Right now, I go through the lights at approx 5500 - 6000 rpm in third gear (700 trans).

Here the D1 is about $500-600 more then the P1.

Glock...so the injectors is all you've done to it? How's the driveability and what did you gain in the 1/4?

Thanks for your input

 

have not run a 1/4 mile yet ..... just had my fmu adjusted ..had a bung welded to my exhaust so they can do a wide band reading to adjust my fmu ...as for driveability car runs fine ..also i installed a msd 6btm

 

In my experience what the dealer told you is true. The P1 begins building more boost at lower rpms in comparison to the D1 and then the D1 passes it (in boost production) near max impeller redline. The D1 is capable of producing 100 more hp (925 vs 825) but this is only if you spin them both to their max speed. Also the P1 is a few hundred bucks less (it was when I bought one). If you're looking for a street setup that's not going to spend most of its time at max rpms then go with the P1-sc.

If you think of a graph of boost vs rpm (boost on the vertical Y axis) the P1 will be a straight line with a positive slope. The D1 is a mild exponential like curve. In the below drawing the P1 is ther red line the D1 is the dark blue

 

I have a D1sc (not installed yet) but I read many posts that the D1 has a more aggressive boost and boost more (200cfm) and comes on quicker than the P1.... Many people that got the p1 say they should of gotten the d1 if they were to do it all over...
Keep in mind, you max boost is near your max rpm too...

Did you talk to ATI?

Rafael

 

Keep in mind that with a street driven car you're not going to be spinning either of these blowers at their potential. To get to max impeller speed with either of these blowers you'll be running the standard 7.625" crank pulley and a 3" blower pulley with a 6000rpm shift point. This is going to reqire massive belt tension to avoid slip as the boost rises. An upgrade to a custom larger crank pulley $$$ would help with this issue.


What are your hp goals?

 

I say get the P1 myself if you plan on keeping it a street car and plan on keeping the Long tube TPI intake on there, here is a copy of a post i made before showing the boost I get.

With the 4" pulley I get this from my data logs.

RPM--PSI
3000-2.5
3500-3.5
4000-4.8
4500-6
5000-8
5500-10
6000-12


Now this is with a D1SC with 3core intercooler stock intake on a stock block with about 40k miles on it. Now as you can see your not getting much boost lower in the powerband, i really don't feel much tell about 4k.

 

I also have the following already done..crane cam 104124, 2800 stall converter, Lingenfelter Superam upper intake as well as the lower intake,52mm throttle body, hooker competition headers, Dana 44 rear with 3:54 gears,Walbro 255 l/ph fuel pump,AFPR,MSD 6A.

I am leaning toward the P1 now, with the 3 core intercooler upgrade. Mostly based on the more linear power curve...but still not 100% sure??

Also, my dealer was saying that I may be able to delete the external fuel pump supplied with the kit as my Walbro 255l/ph pump may be enough...waiting to get ahold of Procharger again to see if that would work.

Also thinking of adding 1:6 roller rockers...anybody think they're worth it?

 

I don't think that you need the higher lift with the 1.6 rockers because your forcing air into the cylinder...... The amount of time the valve stays open is the same. Your just gonna increase valve speed and risk valvefloat.
Of course the higher lift would help a normally aspirated engine, but your already gonna sqeeze air in.

 

Get a D1. you will be so much happier. there is little difference in everyday driving, but the d1 comes in much stronger and you dont have to turn it as hard to make the power. i built a 4.6 in a mustang that started out with a p1, which sucked, and kept locking up and spitting out bearings, and the straight impeller doesn't move much air, then a couple different d1's which were o.k., and it now has a f1-c that was sent to procharger and had an overdriven set of gears put in it. the f1 is fine to drive on the street. now looking into an f1-r.

 

Thanks for everyones input. I ordered the D1 last week, also a set of Accel 24lb injectors. I'll try & post some pics when it's all done.

 

one issue I had installing the D1SC w/Intercooler was that the bracket tension pulley was coming into contact with my dual fan housing. The noise resonated into the SC but was an easy fix, just reposition the fan housing. The D1SC starts to pull strong from the 2500-3000 range then just keeps on pulling. Watch those intake gaskets though.

 

My motor makes peak power at 7400rpm using the d-1sc, and it would have 4psi at 4500rpm with 10psi max at 7400rpm. With 15psi max it makes 1.3psi@ 2700, 2.5psi@ 3100, and 6psi@ 4500. I'd think that lower boost in lower rpms is better for the street. You're never going to see any boost anyway until basically WOT. More low rpm boost means more power there, which will more readily burn rubber. The p-1 may end up being faster off the line, counting on traction, but then the d-1 will be able to make up that ground. Also, on 10psi 10:1 compression last year I dynoed 633rwhp/472rwtq. This year I'm on 8.5:1 compression and 15psi, and am probably making about 660rwhp now.