lunitic5454

iTrader: (1)

I am shooting for a flywheel horsepower of 1200 - 1300hp with a gt88 turbocharged 408. I plan on using E85 to get the boost high enough for my hp goal, but the car will primarily a street car, and I want to keep the convenience of 91 octane pump gas.

My problem is I figured 120 lb/hr injectors will get me to my hp goal with E85, but from I've been told, those injectors are to big to idle with 91 octane. I want to keep my LS6 intake so I need to do it with only 8 injectors.

Can anyone tell me if 91 octane will work with 120 lbers and a factory computer? If not, will a piggy back unit (i.e. megasquirt) help, or should I use 95 lb/hr injectors.

Thank you in advance.

BTW: I'm using HP Tuners

Lonnies Performance

iTrader: (16)

A good tuner should be able to make 120's work on a 408.

You can also reduce fuel pressure to help size them dowm on pump gas.

lunitic5454

iTrader: (1)

Thank you for your input. Has anyone else had experiece with this? Does the year of the computer matter, mine is a '98?

Thanks again for any input.

bug man nrg

Hold on it is not that easy if you are going to run E85 and 91 octane fuel you will need a ecu that will do this for you .this ECU will need a 0-5 volt out put like for the TPS and map sensor .most after market ECU's can do this it is down to the tunner to set it up for you this will take a bit of time to do but it is installed you can run to any pump and pump E85 or 91 octane
here is a quick vid that will give you what you need
http://www.youtube.com/watch?v=a1CzmmMUy50

lunitic5454

iTrader: (1)

Ok..... I don't think I'm asking the question correctly.

I know that E85 and 91 octane require different tunes. I can think of several different ways to do it. I could use two different fuel tanks and just download the correct program in the PCM. I could use 2 different PCM's, each with its own tune and switch between them. One local tuner said that we could set it up with a GM Flex Fuel senser and change the tune based on the sensor input, just like the ProEFI set-up (BTW, Thanks for the link). But that's not my problem right now, I'll worry about that later.

My concern is making just 8 injectors do it all, everything from max hp with E85 to idle with 91 octane. 120 lb/hr injectors @ 60 psi can get to my 1200 fwhp goal using E85 (barely), but once I switch fuels will the 120 lbers be to large for idle. Some people tell me that 120's are to big for pump gas, some say it should be OK????

I guess what I'd like to know is what is the limiting factor with large injectors and idle? Is it the injectors can't function properly with such a short pulse width, or that the computer can't fire them that quick. If the computer is the problem, then will a piggy back or aftermarket unit do the job. If its the injectors, then I'm kinda screwed.