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dual tbi and idle fuel requirement

Posted: Thu Aug 19, 2010 2:28 pm
by 355vette
first post -- I have looked around trying to answer this myself
MSII V3 with 2.89 code
408 CI BBC with tunnel ram intake, 2 GM tbi from 5.7 with 55 lb injectors @ stock 12 psi and I will run 20 psi so should be about 70 PPH per injector. I am making the wiring harness now and am wondering about idle and will those injectors cause a tuning problem @ idle. If they will I would use dual table and only run one injector in each tbi at idle and back to all 4 at a pre determined rpm. If you all think there won't be a problem using 4 at idle I will forget dual table and wire each tbi to one bank and control both banks from one ve table. I'm pretty new so hope this question makes sense. In the future these injectors wil go on a 468 BBC with a 6-71 blower so then I don't think idle fuel will be a problem as the bigger blower motor will like lots of fuel at idle.

Thanks

Re: dual tbi and idle fuel requirement

Posted: Fri Aug 20, 2010 4:21 am
by Matt Cramer
I don't anticipate a problem - we've used four injectors of that size on a mild 350 before, and it's no different from eight 35 lb/hr injectors. An MS1 shouldn't have any trouble with those; MS2 can run much larger ones and still keep the idle as smooth as your cam will allow.

Re: dual tbi and idle fuel requirement

Posted: Fri Aug 20, 2010 7:06 am
by Jack
Matt Cramer wrote:An MS1 shouldn't have any trouble with those; MS2 can run much larger ones and still keep the idle as smooth as your cam will allow.
Matt,

It seems as though you are implying that the MS2 will be able to produce a better idle. If yes, why?

Jack
Triumph TR8 - MS1

Re: dual tbi and idle fuel requirement

Posted: Fri Aug 20, 2010 8:42 am
by Matt Cramer
Jack wrote:Matt,

It seems as though you are implying that the MS2 will be able to produce a better idle. If yes, why?

Jack
Triumph TR8 - MS1
It has about 100 times the pulse width resolution.

Re: dual tbi and idle fuel requirement

Posted: Mon Aug 23, 2010 2:35 pm
by Jack
Ah-ha, just a couple of decimal places. . . .

Thanks Matt,

Jack