diynoob...am I hearing you right? You are complaining that you are making to much boost? Tell me this is a joke? I don’t mean to be rude but the fact is you bolted on a power plant of a blower and now you don’t want high boost? If you wanted something small you should of went to Vortech...or LPE's system (roots style).

The point is or how you look at it you have a nice blower and yes back pressure will cause higher boost and for example I am running 11psi at 5800rpm with full length headers no cats no muffs 3 inch pipe all the way back and all in all my belt is slipping...but one theory I have as well is the differential gears in the back...for example I have 3:73's and since my motor spins so fast with those gear I do believe my belt slips till it catches up...I know a guy with stock gears and there is no slippage on his car and he makes a lot of boost on a big pulley. So be happy for the blower size and it only leaves you room when rebuilding the motor and wanting to make killer power if that is your goal :D

 

the d-1 blows more air or MOVES more air so it does not matter about moving air it is about moving air with force? What i am trying to say is a d-1 and p-1 will both move 7psi...the d-1 will make it easier there for not creating more heat as the p1 will make 7psi but it has to work harder so there for that is more heat..like going to a F-1 it makes 7psi in nothing flat and so there is no heat...see what i am saying? So the d-1 does not have to work hard to make the 7psi but has to work hard at 18psi and so on and so forth.

You have the right idea with the blower you have because if you decide to go with more power you have it...there is always an option i am working on is installing a BOV (blow off valve) and control the flow with that so i dont over boost like what you are talking..What my goal is to make 11psi at 2300rpm or little less and over spin the blower and any extra or over boost will be vented so in theory i make 11psi at 2300-6500rpm and any extra will be vented.

 

Ok, first off, 7 psi is 7 psi is 7 psi regardless of what pumps it into the engine. For two cars having the same boost and one with a P1 unit and the other with the D1 unit, that would mean the units wouldnt be running the same size pulley. The D1 unit would have to have a larger pulley or the P1 unit would have a smaller pulley. The difference between the P1 and D1 is that the D1 flows 200 CFM more, per the ATI website. Now, the only thing that will happen with the same size pulley on each unit is that the D1 will attain higher psi at a given RPM and will achieve more boost sooner than the P1 in the midrange. The D1 is the better unit because it will provide more boost sooner and obviously will provide more power sooner because it flows more air. A P1 unit will have to use a slightly smaller pulley to match the flow of a D1 unit due to the D1 flowing 200 more CFM. The decision you need to make is just how much boost you want. Obviously if you push too much you will shorten the life of the engine considerably and perhaps even damage it. Plus, using the D1 unit, you can use a larger pulley which may help prevent potential belt slippage problems. My engine, completely stock, was getting 10 psi with the D1 unit at redline with the 4.63" pulley, even with the headers and cam change the psi didnt change at all. But the Z06 exhaust system flows better, hence less restrictive. And I got the same response from ATI that it shouldnt be that high. Your exhaust may be causing some back pressure. You have to either swap out your exhaust or put a larger pulley on the D1. Ive thought about installing a relief valve myself in the system. That way you could run a smaller pulley, get more boost down low, and then as the RPM's rise and you attain the max boost you would like, the rest would be vented out. Thats the beauty of turbo systems. These systems can achieve max boost very quickly due to the exhaust waste gates spooling the turbos and then vent excess boost overboard via the relief valve. Superchargers are linear and are belt driven and have to wait for the engine RPM's to increase to drive the supercharger to increase boost. As for your second question, it would probably be better to run 7 psi and shift at redline.

 

av8ter...we are both on the same page on this...yes venting the excess boost to acheive lower boost seems like a killer setup! i am thinking of getting the GREDDY type -r BOV it does both blow off and venting and vacuum so when idle it vents boost:D now just need to save up money and buy it! hhaa haaa

on C4 forum black bart has a vette the is making 7psi at 2300rpm and then vents 15psi for the rest of the rpm

 

I was really asking if the boost curve is any better on a D1 w/ 7PSI vs. the curve on a P1 w/ 7PSI. I know that if they are both making 7PSI at 6000RPM they will both make the same power, but the D1 might have a better curve giving more low-end boost.

 

Its not about PSI its about CFM. Lets say we a have a P1 made to flow x cfm at 6000 rpm and we get 7 PSI of boost. Then we add heads and cam so we get 5PSI and the same CFM so everything is OK. Then we get a smaller pulley and jack the boost back up to 7. We may now be out of the P1 impellors efficiency range. So we get a D1 and the right pulley and put out 7 PSI all is well. Its not the 7 PSI we are worried about itÂ’s the CFM + 200 that we are now flowing. You are doing the opposite which is just as bad. Your taking the D1 and trying to make it run at its low end. It may very well fall out of its impellor's efficiency range so you would be better off with a P1. Maybe its not and your making too much boost, its hard to tell. I though you were going for 5 PSI on a stock car which makes this a no brainer. You need the P1.

Tattooed: Nice to meet you too, I shall take you up on the offer when I get it going again. Your car is very SWEET! :)



[Modified by BrainDrain_dx, 4:55 PM 10/17/2003]

 

Ok. Given the comparison that both units put out the same psi at redline, then that would mean they would have to have different pulleys in order to compensate for the difference in flow between the two units. So the D1 would be spinning slower with a larger pulley. In this case, I would think they would almost be identical throughout the curve because even though they are different in flow characteristics, you made them the same by gearing them with the different pulleys with an end result of the same psi at redline. The only thing that really is different in that comparison is that the D1 is just spinning a little slower but makes the same power as the P1. Thats the beauty of the D1, it doesnt have to work as hard to make the same power as the P1 would. If you would like, I can email you a copy of my dyno.

 

So which "rediculous" criteria did you base your decision on?

I see, so not only did you consciously decide to purchase the kit without researching it (not much was necessary, read below), assumed it was an easy/bolt on install (even though this is rarely the case in the automotive performance arena, especially with major upgrades such as superchargers), but on top of that instead of attempting to return the kit you decided to fix these "major" production "flaws" yourself. It sounds to me like you're aware that supercharger kits require some extra effort to install and debug, and readily accept that, as is evident by your eagerness to "fix" the kit yourself. I don't see where you have a leg to stand on.

I should also point out that before the ATI kit was released I posted about the potential fan issue, which is a well-documented potential problem with all LS1 supercharger kits that require an aftermarket fan. Unless you've been living under a rock or are illiterate you were aware of this before you purchased the kit.

 

I don't mean to pick on you but that is a complete misunderstanding of a turbocharged system.

The turbocharger is "spooled" by exhaust gas, where the exhaust gas, and effectively the intake boost, is regulated by a "waste gate".
The "relief valve", or "blow off valve", or "surge valve", is meant to dump off boost that is the result of timing differences between the throttle position and exhaust pressure (or rpm in the case of a supercharger), to prevent the throttle body blade from bending, or the compressor from "stalling".

The problem with attempting to regulate boost using a post compressor device (like a "surge valve" for example) is that you usually wind up losing blower efficiency, and that its difficult to dial in. I've tried it before on many combinations, but the most successful have been when I used such devices to bleed off large amounts of boost on the street (because I'm too lazy to swap pulleys), and then disable them at the track.

I don't know why no one has raised this point, but from a longevity point of view the boost per say isn't a problem, its the potential for detonation. I'd leave the current pulley arrangement and pull a lot of timing out of the map (especially over 5800rpm), or consider running a smaller crank pulley (several are available). Another solution might be to trade compressors with someone, I'm sure there is someone here looking go upgrade to a D1.

 

LOL. This crap just keeps getting better and better. I knew of the existing problems from researching others, and because of such, I also knew I could fix them. That doesnt mean that every supercharger kit out there requires modifications to work and I cant speak for every kit out there, only the ATI at the time. If correctly engineered, there shouldnt be any issues. If so, then they werent researched enough or designed correctly. But this is all irrelevant. The main problem, which Ive already stated before and apparently I have to one more time is that as many people that did have problems shouldnt have had to deal with it at all at the magnitude that it was. I was capable of correcting them myself so it wasnt much of an issue to me, I just wanted it so I could have some fun, which I am. Plus I have other vehicles to drive in the meantime, but to many others who use theres as a daily driver and arent capable of fixing the issues, Im sure it was quite aggravating and shouldnt have had to put up with it.

Youve got to be kidding!! LOL No, I wasnt living under a rock. Are you disappointed?? LOL. I can tell you one thing related to your comment of your previously mentioned "well documented potential problem" post that may be hard for you to comprehend: Sorry, but Im not a member of the Terry Burger fan club that sits around with dire anticipation awaiting your next post to ponder your next life altering topic worthy of world notification of course which is stemming from your obvious impeccable credentials and experience. Somehow, believe it or not, I missed it.

Rest assured, youre not picking on me and I wouldnt care if you were. I know how turbos work. I was in a hurry and heading out to dinner, nevertheless, Im sure my intent was understood. Oh yeah, I can assure you that Im quite literate. If you would like to critique any more grammar, start with your own.


[Modified by Av8ter, 11:13 PM 11/26/2003]

 

Thread's gone a little off topic :rolleyes: