LT4 Procharger LT4 and 10.7/1 comp.

[northcountry]

Have a LT4 and installed a procharger at 8PSI, compression is high for this, BUT, its fun. Put in 36 lb. injectors, which is to much and going back to 32 lb. and more fuel pressure. Any one have ideas on getting things dialed in for best HP.

 

[6 Shooter]

Charlie,
Welcome to

Sorry can't help u on dialing her in, run my LT4 stock, I Love Her that way! :cool

I'm sure someone here @ CAC will be able to offer u some great advice.

Later,
6 Shooter

 

[northcountry]

Thanks 6 shooter, just found this site tonight and appears that it will be a real help. Been reading some posts on rear end changes and may look into that along with getting the fuel issue resolved.

Thanks again

 

[69MyWay]

Northcountry,

Welcome to CAC. I have no pratical supercharger experience, but I can tell you that a good quality scanner will do wonders for your tuning efforts.

Basically you need a good scanner that will read the O2 sensors. You will then dial the fuel pressure up and down at WOT as needed to obtain the best possible mix. This is best done a dyno, but can also be done with a long strip of quiet private road and a friend to watch the scanner and advise you when you are in closed loop, then to watch while you go full throttle under a load. You can also watch the spark knock module as you will obviously get into detonation if too lean, and the scanner will show you that before you can physcially hear it, or feel it in the seat of the pants.

There are many different brands of scanners. I use a ACTRON brand. They have two different models for pre and post OBDII systems. I ended up buying both because I have both types of style cars to keep running.

You can go straight to www.actron.com and mail order a scanner for your car.

 

[Vettelt193]

air/fuel ratio is the key, as 69MyWay said. It is the single most essential adjustment to our cars. Your setup really requires the bigger injectors... have you tried to tune down the fuel pressure with the 36lb injectors? The stock injectors won't have a good spary pattern if they are adjusted too high, and you will lose power. Also, keep in mind, one of the most important parts of supercharging is to make sure you are not running lean. Too lean and your engine will break, blow, or etc.

 

[Mad-Mic]

8 psi and 10.7:1 comp ratio is a bit high i would think especially if the car is already heavily modded as this one sounds like. high psi and high comp ratio you'll break parts mainly head gaskets it's not enough pressure to lift the heads off the studs or anything but i'd take that into consideration once you get it tuned in you might want to back down the boost to maybe 6 psi.

i'm sure someone with a similar setup will chime in here and help more.

 

[Vettelt193]

compression on a stock LT4 is 10.8:1 so I assume it has already been bumped down a little.... ATI prochargers come with intercoolers, so more boost can be applied safely. LT1 can go to 9psi, so I assume, without any hard calculation, the higher compression LT4 can go to 8psi without troubles

 

[c4fan]

Welcome to CAC northcountry. This by far the best site for corvette owners.:BOW I bought my 87 earlier this year and have learned so much from the members here. You can find out anything about your car from these forums. I hope to install an intercooled ProCharger set-up on my car in the future. Unfortunately putting a kid through college takes priority. Living in CA. it is the only smog legal way I can make a major horsepower increase that I have found so far other than nitrous and that may come down the road also. Need to stay ahead of all these undeniably fast imports starting to litter the streets. I figure that with the supercharger and some head and cam improvements I'll be running with the big dogs.

 

[northcountry]

Thanks
Lots of things to work on. I will buy the scanner and use the friend to watch, No dyno in Fairbanks.
I went from 28lb stock injectors to 36lb. Little to much fuel when I get on it, lots of black smoke. So plan on going to 32lb and play with fuel pressure. Have installed a fuel/air meter so plan on running on the rich side to stay away from most problems.
It is intercooled, from Procharger.

Thanks to all of you guys for the help.

 

[bob eshleman]

pro charger

hi try looking into inter cooler and or h2o injection-will help with higher compression. good luck, bob.

 

[6 Shooter]

Re: pro charger

hi try looking into inter cooler and or h2o injection-will help with higher compression. good luck, bob.

Bob - Welcome to

 

[northcountry]

Already has the intercooler, the main problem in Alaska is the poor fuel (octane) race fuel unleaded 100 is 7.50 a gallon plus shipping of 25 dollars for 5 gallon cans. So been trying to find another way to boost the octane. Toluene is the way to go that I read. May try 10% and go from there.