I have read through the recent posts here and I hate to bring up the same subject but I will This is for a non-internet friends car I have been helping with. I have little experience with the pcm on a 90 but I assume LT1 edit isnt an option. I have been more into LS1s lately and have used electromotive and DFI systems on several cars so I am familiar with those.

If this were your car - 90 vette, 10psi intercooled P1SC ATI, 30lb injectors, TPIS custom chip, 355 inch LT1, 9.2 cr forged pstons, AFR heads, mid sized CC roller etc. What would you do for a decent user adjustable fuel/spark system?

Right now the car has an FMU/inline pump and MSD 6 and just made 450rwhp through an A4 but at higher RPM its getting lean and I cant just grab a laptop to fix it. Fuel pressure is staying above 99 PSI but I have never been a fan of FMUs even though it is working..

I'm just curious what the best and most cost effective option would be to go with a '90. The owner would rather have something he can adjust and doesnt want to be mailing chips back and forth, I'm just not that familair with this generation of stock engine controls and any suggestions would be appreciated. An upgraded in-tank will put in soon so that will be OK, its forward of that I could use a little guidance

 

First "if" the duty cycle of the injectors are at 100%,he will need to chang then.I was able to get 426 HP out of my setup with 30LB injectors but they were at 96% duty cycle, just an example but you get where i am going with this. Now i have 42LB injectors and making more horse power my stock pump and ati inline are unable to keep up so a new 340 walbro is going in. There are no quick fixes or cheep ones usualy. I would recomend a FAST system but they run around $1000 outherwise he is sending out for a new chip every time he makes a change wich can cost more than $1000' after a few years.Depends on how long he wants to keep the car.I hope i have helped

 

Tunercat is similar to LT1/LS1 edit and it will work on a 90' C4 if you can burn proms for it.

www.tunercat.com

 

The injectors are well past 100% and the FMU is doing what it is supposed to but it is very hard to get a consistant a/f. The car easily dynos 450 right now but its just running out of fuel on top and its way too fat midrange. The fuel pump is getting changed to the biggest in/tank one we can use so that wont be an issue.

When running a FAST system does it 'piggyback' the stock ecm and still use or is is it a complete stand alone fuel/spark system. What is ther website, still cant find it - sorry for the dumb questions

 

Thanks, I'll look into it

 

Oops, the car is a '92 - pretty sure LT1s didnt exist in '90