Yeah, he has huge ones...I think like 500lb/hr. The problem is that they are low impedance. They have just recently come out with some 80lb high impedence injectors. I just verified yesterday that they are available. You could run a piggyback driver to fire the low impedance injectors, but it is a pain.

JRider,
I don't see why you couldn't do that. Those throttle bodies aren't very big, so it would depend on the power goals as to if they would be big enough. You would have to have them or get them real cheap to make it worth it. The aftermarket ones aren't that expensive.

Eddie

It's never a good thing when you have an impotent injector!

thanks for all the info. My stock 575 SCI came from Advantage with a superchiller and 3" pulley. Also came equipped with an exhaust pyrometer. And from experience with the set-up, it stated to run lean at 4600 RPM. To me that is proof the factory throttle bodies lack flow and adequate fuel delivery. Talked to FAST since they offer 4-barrell high impedance injectors, but they do not recommend them on blower engines. currently looking at injectors mounted in a throttle plate with air only throttle bodies.
Currently rebuilding total motor with Hyd. roller, Dat Pro 1's and good gaskets. Will multiple injectors work with factory ECU?

I was just thinking that all the merc linkage is good, the IAC is there, and the arrester looks good and is already there. Why not make use of it? ditching the stock injectors would most likely help the TBs flow.

I'm going to look into using the stock throttle bodies as air only. But i keep hearing they do not have enough air CFM above 5000 RPM. What is the CFM on the stock throttle bodies?

I Think 670 each but without the stock injectors in the way they should flow better. How much better...I dont know. I know Steve Zuckerman sent his out to have some mods done so the would flow more.

Adavantage_575. I am in the process of doing the same thing as you. I have a Littlefield 871 that is stripped and the whipple intercooler that is ready to go in. I have talked with Steve quite a lot along with Eric his motor man and EFI tuner. I will try and find more info the the TBs

Eddie,
have you looked at a driver box for the low Z injectors? Depending on the output of the MEFI.. (switched to ground?) to fire the stock injectors a driver box can open up the injector world to much bigger squirts!!

Dick

JRider, let me know what you find out. I think 1340 CFM is a little shy for an 871 Blower in the upper RPM band.

I have. I mentioned it in post 11. It is just a pain and something else to go wrong. The 80# er's are available now, so it's no longer an issue. (8) of them will support over 1400 hp.

The way to get the 575 injectors to flow adequately at a pulse width that doesn't burn them up is to install an adjustable fuel pressure regulator. Turn up the FP, turn down the pulse width.
The guys that modified my throttle bodies say they are Merc/GM rated at 670CFM, but on their flow bench they only flow 640, probably because of the big injector sitting right above the bores. Mine now flow 740 each (with the stock injectors) for a total of 1480. I think side mount injection and removing the TB injectors would result in a big flow increase too. Hmmmmm. Maybe get that missing 30CFM back or even more?
Eric did have to completely remap my injection after this but, knock on wood it's run great ever since, evidenced by my repeatedly broken drive :eek:.
Here's a pic. Eric has my program stored if you guys want to do this upgrade. Oh yeah, Eric also upgraded my manual fuel pump to an Eickert, and went to bigger lines.
EB Marine #615-714-2944.
Best Regards,
Steve