Injector Size vs Idle Mixture Control, E85
Injector Size vs Idle Mixture Control, E85 Hi all. I'm assembling a 6.2L LS-3 with an LSA supercharger, and will be dedicated pump E85 use only (E60-E85 range). Medium size 224/232 cam, and overdriven supercharger ratio using 10" crank pulley (stock upper pulley). On sizing injectors before purchasing, it looks like 1300cc is about what the engine will want for 750'ish hp. My concern is, will this be too large of an injector to have good idle controllability? Meaning can the pulse-width be small enough to produce proper A/F at warm curb idle speed, say 750rpm? No problem to use a 1:1 referenced fuel pressure regulator to help, but will that be enough? I think that would only differentiate fuel pressure by 10-14psi?
Be great to hear some opinions of those that have built and tuned similar. I'll likely post same question on HP Tuners forum, but have not yet.
Thanks.
Be great to hear some opinions of those that have built and tuned similar. I'll likely post same question on HP Tuners forum, but have not yet.
Thanks.
Last edited by FormulaBoat; Dec 10, 2021 at 08:07 AM.
As stated, spend the money on buy good injectors. ID's, FIC, DW, etc.
There's a lot of places you can go cheap on when building a car. Injectors is not one of them, I don't GAF how many people on the internet say so.
Boost referenced regulator is the best way to go IMO.
You're gonna need two fuel pumps to push that much E, or one BIG one.
There's a lot of places you can go cheap on when building a car. Injectors is not one of them, I don't GAF how many people on the internet say so.
Boost referenced regulator is the best way to go IMO.
You're gonna need two fuel pumps to push that much E, or one BIG one.
Based on the HP Tuners comment, I'm guessing your going to use some stock ecm? I have tuned a LSA supercharger with ID1300 in it. It has a Holley running it. Starts, idles great and doesn't have any overly stinky fuel smell. I have the timing at 20* at idle.
Im probably at/close to the HP you are wanting to be.
I run Bosch 210's, dual 450lph Walbros (both on full time), straight E-85 (always tests at 75-85%), and use HPTuners. Car starts, idles, and drives very nice. 800rpm idle, and injector duty cycle has never been more than 62%, so too big? Yes, but haven't experienced any I'll effects.
FWIW, my buddy is making quite a bit less HP, and runs 93 octane unleaded, also with Bosch 210's. His also starts, idles and runs very well, and has never seen more than 30% IDC, running Holley Terminator X.
I run Bosch 210's, dual 450lph Walbros (both on full time), straight E-85 (always tests at 75-85%), and use HPTuners. Car starts, idles, and drives very nice. 800rpm idle, and injector duty cycle has never been more than 62%, so too big? Yes, but haven't experienced any I'll effects.
FWIW, my buddy is making quite a bit less HP, and runs 93 octane unleaded, also with Bosch 210's. His also starts, idles and runs very well, and has never seen more than 30% IDC, running Holley Terminator X.
TECH Apprentice
Joined: Oct 2015
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I run the snake eater 1500 in my LSA. E85. But I have to big of a cam in it and it idles a little rough. But no problems so far ,year and half. 620 LBS logging them. If it was daily I would pony up for some high end ones.
