Leigh,
Thanks for posting this. I find it quite interesting.
What is the "Max Air/fuel: 17.5" all about?
I assumed it was your air/fuel ratio, but the chart doesn't show anything
above about 12.75 and low of ~11?
I have been led to believe that max power for a gasoline powered engine
should be about 12.5:1 air/fuel ratio, which puts you in the ballpark above
~4700 rpm and somewhat to very rich below 4000 rpm.
Is there a way to lean it out a bit below 4000 rpm and keep the top end in
that same range?
Also your torque and horsepower "peaks" are quite a bit lower than I
expected...?? Lower than the book stated peaks of 4400 and 6000 rpm
respectively...(for the SU cam)??
Just out of curiosity, has anyone tried a set of 40mm DCOE's (or equivalent)
on the U20 instead of the 44/45's?
( I'm leaning towards thinking the 44/45's are too much for a "street"
engine, no personal experience tho.)
I have to say I know zip about carbs, but what size "choke" are you using?
How does the different "chokes" effect performance?
Leigh,
I am trying to understand your #'s and how to increase the performance, not
trying to pick apart your baby.
You've done a great job on "Zippy" since you picked it up. Keep up the good
work!!
Daryl
'66 1800 work in progress......
----- Original Message -----
From: "Leigh Brooks" <shifty@shiftco.com>
To: "Roadster datsun roadster mailist" <datsun-roadsters@autox.team.net>
Sent: Thursday, March 23, 2006 3:42 PM
Subject: Zippy on the dyno
>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
|
