May have been wrong all along

[Bruce Plecan]

Well, at dinner tonight Sleepy and Bashful got into a heated debate, and I
couldn't settle the disbute.
The issue was how wrong and yet right GM is in there injector sizing.
Lets just look at a 350 v8 say 8D mask.  Bare with me as I just round
numbers off.

25 times 8  =  about 200#'s per hour, for a 240 HP engine.  That is way over
sized.  In the past I just dismissed it as allowing for wear and tear and
some PCV levels elevating.

I think the rational, is more the ratio of (yes) the mechanical wear and
tear of the system but to make the BL alot more corrective in nature.   ie
as long as you have room on the low side of the injectors operating range
you'll be OK.  I see any P+H injector, at it's min linear time will make for
an easy to tune and FORGIVING calibration.

Also, explains SEFI.   By observation of my GN the 40#/hr injectors with a
mild cam was much smoother at idle then the oem ones,  and with the 55s are
just as smooth as the 40s.   While I could probably twist it's tail and run
550 HP that wasn't my goal, but rather I wanted  a least 450 with a little
room for more.  So went with the oversized 55s, but they worked out to be a
**nice** size to work with.    Also, reduces the work load on the fuel
delivery system.

Might again explain some conditions where there is trace detonation when
trying to run 350HP which the stock ones should support.

In playing with the 355 (cross fire TBI) I had been able to run good numbers
with the 85s but it just seemed so much easier to get the numbers with the
95s, even though still at the 325 HP level..

YMMV
Bruce

----------------------------------------------------------------------------
To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org