May have been wrong all along

[Dave Zug]

I started saying this (and was ignored, again) about a year ago when I was
using stock TPI 22's on a 390HP 383. thats a BROAD CURVE 390 HP. The peak DC
was 86% for an INSTANT during ONE shift. The other HIGH load DC's were like
60's and 70's.

I now am running the same 383 with 70 extra DYNO's RWHP of N2O sucessfully
using SVO 24's.  the idle is teriffic (thanks partly.. well, mostly... to
the new '730 conversion)


----- Original Message -----
From: Bruce Plecan <nacelp at bright.net>
To: <gmecm at diy-efi.org>
Sent: Wednesday, March 14, 2001 7:58 PM
Subject: May have been wrong all along


>
>
>
> 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
>
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