Bob,
You would be doing real good to get more than 165 out of your motor with
11:1 and 28 mm chokes. Carillo rods IMHO won't be needed until 14:1. I
ran stock rods up to 13.5:1 without any problems. I think I've told you
off list what kind of compression we have run in the past to get over
200 hp with 28mm chokes.
IMHO desktop dyno programs are for bench racers and if you want cold
hard figures hook the flywheel up to a real Dyno. Our real figures never
matched up to those programs.
Is 90 lb/in what piper recommended for seat pressure. To clarify are you
running 90 lb/in or 90 lb/ft seat pressure?
Mike
-----Original Message-----
From: owner-6pack@autox.team.net [mailto:owner-6pack@autox.team.net] On
Behalf Of Robert M. Lang
Sent: Monday, December 23, 2002 5:45 PM
To: 6pack@autox.team.net
Subject: Desktop Dyno
Hi,
I have a dumb question. I would like to converse with folks that have
run
Desktop Dyno to compute theoretical power curves for TR6 and have then
gone to a dyno to see if the numbers are right.
According to the numbers I'm putting in, my current engine should have
peak HP in the 195 HP range and nice fat torque from 2000 to 6000 (169
ft-lbs at 2000 to 168 ft-lbs at 6000 with the peak or 209 ft-lbs at
4000).
This seems a bit more than I thought I should be getting, so I'd like to
swap stories with anyone that's actually tried to correlate the numbers
with reality.
I know I'll get at least one "so Bob, whacha running?" query so here it
is
in a nutshell:
TR6 motor, .040 overbore, forged dome pistons, head milled to 10:1
yielding about 11:1 total compression ratio, mild port-match, early TR6
head (narrow port), Weber DCOE 40's (28mm "chokes"), Piper BP270 cam
(264
duration, .410 lift at the valve), balanced (recipro on the spinning
parts, rods balanced end-to-end), stock valves with a three-angle valve
job and stock rockers with "treated" Piper single coil springs (about 90
lb/in**2 seat pressure), tubular pushrods.
I run leaded race fuel because the head never got the hardened valve
seats, static compression is about 240 lbs/in**2 with the engine hot.
For some reason, nearly 200 HP sounds like it's a bit optimistic. I
should
think that 160 - 165 was more like it, but maybe I was too conservative
with my estimates. I can tell you that the first time you tromp on this
baby, it scares the heck out of you! But I thought that was the gears
and
the slicks, not ultimate HP. If it is HP, then I actually should be a
bit
quicker (owing to the curb weight of 2000 lbs (mandated by rules).
The reason I'm asking all this stuff is that "Charlie", my machinist has
a
pile of new stuff from me and this setup should yield 210 HP peak (at
6500) and torque peak up quite a bit (160+ torque from 3000 to 6500).
Strangely, this might be a bit too radical for my uses - but I coould
probably "do" another cam before Charlie gets to my job... maybe I
should
break down and buy a set of Carillo rods! The $2k price tag is hard to
take, though. Really hard to take!
Yeee - ha!
rml
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