Andrew, et al.,
For the SU 2000, peak acceleration is obtained by shifting at about 5000
rpm. Seems low, but try some time to speed runs and you will find this
is the quickest. Easier on the engine than running to redline. You can
estimate the shift points by plotting the factory torque curves versus
road speed, using stock gear ratios and final drive you will find the
curves cross at about 5000 rpm. Peak sustained acel is obtained by
maximizing the area under these curves (left for the read to solve the
calculus problem). The plots I did a while back shows the following
optimum shift points:
1st to 2nd 5300 (rpm in 2nd=3300)
2nd to 3rd 5200 (rpm in 3rd=3800)
3rd to 4th 5000 (rpm in 4th=3800)
4th to 5th 4700 (rpm in 5th=4000)
Now if you extrapolate 5th to 7000 rpm you get 160 mph, yeah right!
Drag, rolling resistance and other forces really push the shift point a
little higher, but no need to go to 7000 or even 6500. The Solex engine
produces peak torque at a little higher (~10%) so shift points should be
a little higher. Unless your engine is modified to yield a torque peak
at higher rpm, no need for high revs.
Todd Osborn (buried the tach twice on missed shifts at redline: 2 blown
clutches, one cracked piston)
68 2L DATSFUN
San Jose, CA
Andrew Murphy wrote:
>
> Okay List,
>
> Once more unto the breach. I have heard a lot of stories about these cars
> ability to go over 6500 RPM. I have heard that these engines love to live in
> the 5500 range.
>
> So when Fred Katz pulls away from Calspeed when they are both doing 3500
> rpms, but Calspeed says that the solexes really shine when he is on the
> track and approaching 6500 RPMs, what does this tell us?
>
> The tach on my 67 2000 goes yellow at 6500 and red at 7000. I have always
> thought that you should stay out of these ranges for any length of time.
> Personally, I have only had my car over 6000 once for any length of time and
> the engine was really screaming. I can only get over 6000 in fourth gear. If
> I move to fifth gear, it peaks out at about 5700-5800. Hard to tell because
> let's just say my tach is doing the mambo at that speed.
>
> My girlfriend's 99 BMW Z3 2.8 liter v-6 redlines at 6500. But of course her
> engine puts out more power than mine at a lower RPM rate. Seems like once
> again the list has gotten onto the "fast track". Turbos, SUs, Solexes.
> AAAAAARRRRRRRGGGGGH!
>
> Me, I just want the courage to take my 34 year old engine over 7000 RPMs
> without fear of launching the head through the hood. When I finally do get
> my car on the track, I intend to do just that. 7000 or bust!
>
> So is that the final answer? SUs are better on the road but Solexes rule the
> track? I think Vic Laury and Craig Carter may have some things to say about
> that.
>
> Andrew Murphy
> 67.5 2000 Solex (Never been on the track)
> SoCalRoc
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