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Re: Zippy on the dyno

To: Leigh Brooks <shifty@shiftco.com>,
Subject: Re: Zippy on the dyno
From: RacerY@comcast.net
Date: Fri, 24 Mar 2006 21:43:58 +0000
That's cool, Leigh-
did Carb Connection do the work?

The raw numbers seem low- which, often, is a good sign.  They're not trying to 
shine you on with artificial corrections.  A chassis dyno's really good for 
comparing 'before/after' mods, but the absolute numbers often don't mean too 
much.

If they recommended a bigger air corrector ('air jet') then they think you're 
running rich in the mid- upper range. And that may be true- up to a certain 
point, leaner DOES make more power.  It's very engine- dependent, though.  Look 
at the tailpipes of most race cars- they're grey- to- white in color, meaning 
that they are running significantly leaner than any street car should.

If they didn't over- smooth the numbers, that's a nice, even curve- you may be 
hard- pressed to make much of a change and keep it looking so good!

As to the '17.5' number, it's just a hole that the computer picked up- possibly 
from an off- idle transition, or even from before the engine was started!

Toby
also in Seattle
-------------- Original message -------------- 
From: Leigh Brooks <shifty@shiftco.com> 

> I took Zippy to get some dyno tuning, here's the results: 
> 
> 1969 2000 
> "A" cam 
> 44 PHH Mikuni Solex 
> Fuel Jet: 135 
> Air Jet: 140 
> Pilot Jet: 55 
> Accel. Jet: 35 
> 
> 
> Max Horsepower: 89.4 
> Max Torque: 101.4 
> Max Air/Fuel: 17.5 
> 
> http://www.shiftco.com/features/zippy/dyno/power_torque.jpg 
> 
> http://www.shiftco.com/features/zippy/dyno/air_fuel.jpg 
> 
> Tuner recommended a 150 idle jet (air jet?). Said it was pretty close 
> and he synched the carbs a bit. 
> 
> Leigh Brooks 
> NWDE 
> Seattle 




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