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RE: Problems at 4500 RPM

To: "'Ted Schumacher'" <tedtsimx@bright.net>,
Subject: RE: Problems at 4500 RPM
From: "Jim Swarthout" <jswarth1@tampabay.rr.com>
Date: Tue, 24 Jun 2003 00:02:36 -0400
And a stock engine does not go flat at 4500+.  Add another 700 rpm and 
they will start to soften but sitting new in our showroom they would 
easily turn past 4500 rpm.  Ted

Ted,

Interesting! Let's hear what actual drivers have to say!

Acceleration flattens out at 4400 rpm and nearly disappears at 4800 (in
3rd 
gear it takes a long time to go from 4800 to 5000 rpm).
The same thing happens in second gear but is less noticeable.  I
couldn't 
sense anything in first gear (I guess because it all happens too fast).
I 
didn't have a place to test it in 4th gear, but I'd imagine it to be
*very* 
definite (and therefore easier to measure).

Test conditions (since an earlier message mentioned some effect of 
temp/humidity):
temperature: 51 F
humidity: 81%
elevation: approximately 100 feet

Stock '69 engine, but with lightened flywheel, electric fan, and Crane 
XR700 electronic ignition)

I'll be interested to hear how my results compare with everyone else's!

Regards,
Cregg Cowan
71 TR6 (w/ 69 engine)


Referencing Page 10,Figure 3 in the Triumph TR6 Competition Preparation
Manual (which compares dyno runs of a stock TR6, TR6 w/10:1CR, TR6 with
S2 cam/10:1CR, and TR6 with S2 cam/10:1CR/Header) , the stock tr6 makes
max HP at 4700 RPM (103 HP) after which it falls off sharply.  Therefore
I would say (according to the chart) that one should use 4700 RPM as the
max shiftpoint (although personally I prefer 4500)

Hugh Barber
Hollister, CA


I would have to say "peak " horsepower is reached at 4500 rpm, for later

models @ 104hp. After this the hp falls off even though rpm's still
climb.


Mitch Seff
Oceanside, N.Y.
75 TR6


In a stock car, I'd have to say things "stop happening" at around 4500,
more or less. Change to K&N's and it does up a tad, maybe 150 RPMs. 
 
regards,
Bob "seat of the pants" Lang



Jim Swarthout

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