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TR Fourbangers - max RPMs

To: triumphs@autox.team.net
Subject: TR Fourbangers - max RPMs
From: John Cowan <jfcowan@pacbell.net>
Date: Mon, 27 Mar 2000 20:45:25 -0800
Wise words from John H. Sheally II, posted on a Morgan list at www.gomog.com

As to the Turbo/blower/super charger units for a TR4. Paxton, Judson and Rootes
come to mind and have been used in the past.The principle was the sliding vane
type blower system.

N.B. They should only be used in the TR4 when you are not going to turn high
RPMS with the engine for it has always had a heavy crank supported by only
three main bearings. In the best of conditions , with a balanced engine, rods,
crank and flywheel pressure plate, the engines have never liked high RPMs

The TR4 delivers great torque if one uses his head and not his foot and 
chooses a
blower as mentioned.  You would have a very nice unit. I used to race TR4s and
had the pleasure of owning and racing Group 44s last solid axle car the 65 
National
winner.  I stayed with SU carbs and later 45DCOE Webers and never a blower
because of the rules at the time. I was always pleased with my engines running
them at 14.5 comp ratio,steel head gasket F,D,and G3 cams and some additional
grinds,overdrive in all four gears,various overbores and RPMS at 65 to 7500 but
always with a eye on balance and the bottom end got rod and main bearings quite
often to make the bottom end live under those conditions. The point is the 
TR4 is a
good strong bottom end torque engine that 5500 and under RPMS lives well but
when asked to turn over 55 has to be maintained on a regular basis with 
change of
rod and main bearngs to keep the crank alive. Bearings cost much less than 
engine
rebuilds. Make sure your TR4 is balanced and blueprinted where possible. Be
warned if you find on of the mentioned blowers usually some adapting and 
machine
work is required for fit and by all means top it off with a rev limiter. I 
prefer the
MSD with soft touch. and remember the saying of the drag racers (Injection 
is nice
but I would rather have the engine "blown").

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