[Diy_efi] RE: Diy_efi digest, Vol 1 #413 - 12 msgs

[bill.shurvinton at nokia.com]

The gearing bit I have no problem with. My car weights 1250lbs (and =
needs to loose some) so has a very long 1st gear by most standards. =
Because it has very little inertia any lag in throttle response is very =
obvious.

I can't grasp why terminal velocity tune loses power in lower gears =
unless you are deliberately overfuelling to keep things cool though. I =
need to go away and think about that. I will 'get it' eventually :-)

Bill

-----Original Message-----
From: ext Dave Dahlgren [mailto:ddahlgren at snet.net]
Sent: 19 December 2002 10:26
To: diy_efi at diy-efi.org
Subject: Re: [Diy_efi] RE: Diy_efi digest, Vol 1 #413 - 12 msgs


You need to think in terms of cylinder pressure. Big truck long hill =
same rpm
and map big cylinder pressure. same engine in a 2000 lb car going =
downhill at
WOT very little pressure same rpm and MAP, at least until you chicken =
out and
lift. But I think it Makes the point. the only time the two engines see =
the same
load is at terminal velocity for both at the same rpm. If you tune for =
terminal
velocity with no fuel or timing modifiers for the lower gears and less =
load you
are giving something up power wise. To a certain degree the OEMs seem to =
play
with gearing to make some of these scenarios equal. Small light car take =
gear
out,big truck put gear in..=20
Dave

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