I am new to supercharged motors as I have just installed a Procharger on a '96 Z-28. I plan on running 8-9 #'s of boost (stock motor w/16K miles). I've been told that the stock 24# injectors are marginal at this level and should at least upgrade to SVO 24# injectors to avoid lockup at higher fuel pressures (85psi and above). With the 24# SVO injectors I should still be able to leave the PCM alone and continue the use the FMU (or so I've been told). My real question is this: Is it recommended that I upgrade to larger injectors and use a service (like PCMforless.com) to re-program the PCM and continue to pay them each time I want something changed? Or, is it more adventagous to purchase PCM software (like LT1 edit) and do the programming myself??? I have several changes that I need to do to the PCM currently. I am leaning toward purchasing a PCM editing program and cable because I like the idea of being able to tune myself, but I want to make sure there is a safe "starter" set of parameters for my application and that the program has a detailed set of instructions and/or internet support. Any input from experienced users as to what direction to go and with what programmer or software would be greatly appreciated. Thanks for your time.

 

you're gunna blow your engine in no time with 8-9#s of boost.

 

Just installed an ATI charger on my 95'. Obsolutely no mail order tune! You need to have the car dyno tuned to perfection to give your motor even a fighting chance of survival. No joke @ 8 psi the piston rings will hate you and eventually give up. The charger I installed, is on a stock motor so I went 7 psi. Hopefully buying myself some time before I rebuild the engine. There are many topics discussing boost levels on this board. I would also ditch that FMU and go 38lb or higher injectors. The FMU is garbage.

Adam

 

It's surprising how opinions vary so much...most people I've talked to including ATI say that it is safe to run up to 9lbs of boost on a stock shortblock, but lets say for precautionary measures, I run 7 lbs. of boost. I am still looking for information regarding PCM programing. Any recommendations based upon previous experiences with tuning would be appreciated.

 

Well the varying opinions will all conclude to the inevitable with the stock motor. If ya don't believe us just wait. Running stock tuning with 10.5:1 compression is not going to corelate to longivity. Ringlands will break eventually. Just be prepared. If your absolutely dead set on running the stock motor, pick up a set of AFR heads with large 78cc combustion chambers to lower the compression on the stock motor. You should then be able to run the boost you wanted for quite some time with a correct tune.

 

Your in the best place for advice, on this forum. While ATI may state you should be safe up to 9 lbs..they won't be buying you a new motor when she goes. I'm dead smack in the middle of tuning my car..back to the dyno this tuesday actually. Regardless of the amount of the boost a tune is crutial. ATI also states in there install manual how to tune your FMU for certain injectors...that is no the proper way to really tune the car. I'll tell you from my "current" experience and I've talked to Ivan ( madwolf tuning ) and he said he couldn't accurately tune my car from mail order. He mentioned he could "safe tune" the car but it would not be optimal. Ed Wright is also an awesome mail order tuner for supercharged applications. The shop I have my car at now mentioned although he does excellent work it takes about 3 tries of mailing back and forth to get the tune "right on". We are currently using LT1 EDIT and a dyno to get mine all set up.

Adam

 

Intercooling yes, you can run that much boost. What I would do is

1. compression check
2. leakdown test.

if those pan out ok, then put the blower on. If you're going to run an FMU, you can use stock injectors, but I'd have at least an inline booster pump. If you're going to run bigger injectors, then do the mail order or LT1 edit program. Even with bigger injectors, I would still advise minimum of a booster pump.

I don't know what you guys are doing with your blowers/turbos, but I put my ATI on at 54K miles and I currently have 115K miles on my car. I still have my bone stock engine. Did I mention no problems.

Main thing is to have enough fuel and make sure that the engine doesn't knock. knock will kill your engine. I run 11.5 to 11.8:1 air fuel ratio and I'm running 20* of timing and have no problems. I do my own tuning.

Do the above and be smart about it. If you need help PM me.

 

I understand that people consistantly damage their motors because of a lack of understanding regarding superchargers and their related boost requirements. I also know that it is possible to run a safe combination on a "stock" motor with reasonable expectations of performance and durability. People are on this message board and several others that have done it the right way such as "DarkblueTA". Thanks for your post, I will contact you! Detonation, excessive cylinder pressures and heat all contribute quickly to a short-lived motor irregardless of how well built it is (lower compression, blower pistons, forged parts etc.), even if it was designed to be used in a supercharger application. I should have been more specific with information regarding my installation, but I was trying to keep the post to a mimimum. Here goes...I am using the ATI intercooler, FMU (for the time being) & inline booster fuel pump; I have a selection of pulleys for varying boost, currently using the stock 24# injectors and the motor has 16K miles (good compression and leaks okay...motor considered to be in "excellent working order). What I should have said was I am new the supercharging "LT1 motors". I understand the corrolation of boost to stock engine longevitey. I also do not plan on running 9 lbs. of boost from the moment I start the engine. This is something that I plan on doing over time...engine permitting. I plan on "creeping up" on the higher boost levels when I feel comfortable. This leads me back to my original question...lets forget about mail order PCM programming and concentrate on PCM software and the necessary cables/hardware. The advise I am looking for is the recommendation of a good software program that has a baseline for my application and a detailed instruction manual and good tech support if needed so as to be able to get the vehicle up and running safely and then have the capability to tune it based on its own parameters (on a dyno or on the street/track) without having to be an Engineer. I have moderate computer skills and a relatively good understanding of EFI and belive I have enough common sense to do the tuning myself or with the guidence of a chassis dyno shop. I am just looking for some insight based on someone elses experiences with different PCM programing software and their tuning efforts. Sorry for the lenghty post.

 

For some reason the LS1 can take more than the LT1. Maybe it's the half point less compression? I don't know. I've visited a site with a guy and the stock motor running the QMP turbo kit with over 100 dyno runs on the stock motor with alot of them over 700 Hp. Please show me a LT1 doing the same. The LT1's don't last, even with good tuning. There have been many proment members that have had their cars tuned right and they still went. There is always someone that gets alot of miles out of the stock motor that thinks everyone is on crack, all I can say to that is just wait and experience it yourself. My stock motor lasted a year and a half and almost 15K miles and was professionally tuned before a ringland went. I since do the tuning myself.

If I had to make a guess, I would say at least 80 percent of LT1's with stock motors will need rebuilding within 2 years of putting on FI. It might be more. With odds like that I would heed warnings. My $.02 FWIW

 

Don't be led to believe that "X psi of boost on a stock LT1 is safe". Most people equate "safe" with OEM levels of longevity, and it just ain't gonna happen! Believe what you will you really should trust me on this one.

Now, that said, a carefully tuned and driven LT1 with low boost (~6 psi) will PROBABLY have reasonable longevity. But don't expect to last like a well cared for stock motor will. Get into the 8 psi range and it won't last as long. And 10 psi on a stock motor is an invitation to the "rebuild club". The LT1 is an excellent motor that was never intended for boost. The CR is quite high for the tecnology involved already and even stock non-boosted motors with stock tuning will ping on premium. What saves them is the knock sensor circuitry. But the stock pistons, while fine for a stock non-boosted motor, are too brittle to withstand any serious detonation. Once you get to 8-10 psi, detonation is inevitable on pump gas and that will destroy the pistons. If you severely retard the timing and richen up the mixture under boost you can inhibit detonation, but you will lose substantial amounts of hp and there is a limit to the effectiveness of these tuning techniques anyway. Water/alky injection is a big help in this regard, but is also no panacea.

Basically, the stock LT1 is not very tolerant of boost. A 6 psi setup with a "safe" tune, while probably giving acceptable longevity, will not gain all that much power with the requisite retarded timing and rich mixture. If your performance goals are in the range that a 6psi setup provides I think you would be better off with a heads/cam/induction/exhaust package.

Rich

 

I expect the inevitable...FI will take its toll on the stock LT1 motor over time irregardless if I run 6 lbs of boost or 10. The natural progression of building a "hotrod" is to modify and replace the "weakest link" then modify again and replace the "weakest link" again, etc. etc. (at least that's the theory for a basic street car). I fully plan on building a blower motor so that I can completely enjoy all the benefits of maximum boost, I am crawling before I walk so to speak. I really didn't want to get into a debate regarding longetivety of the stock LT1, as I am more looking for recommendations on tuning software as I stated before. Thanks to everyone who has taken the time to answer this post so far. We could go on forever about what the correct combination is for different levels of boost, but I am more interested in the tuning aspect and would like some recommendations on PCM programming software. Thanks for your time!

 

The FMU has an undeserved bad rap. It's a crude tool though and to be used safely it will basically make the car very rich everywhere (under boost) unless other changes are made. I think that there is no substitute for tuning with a wide band and would say that it's necessity for a blower car. What ever method you use to add enough fuel, I think you need a way to tune the AF ratio via the PCM in response to wide band readings. IOW, if doing it yourself you will need LT1_Edit and an LM1 wide band. Or, have it done by a tuner (in real time, not mail order, if possible).

Rich