It seems I've a chance someone here knows what the inertia is of the rotating
parts of a (standard) TR4 and TR6 engine?
PS : most chassis dyno's are measuring horsepower out of the acceleration of
the very heavy cylinders (great inertia). The wheels of the car are resting on
these cylinders and accelerate them during the runs. But the engine has also to
accelerate the rotating parts of the car(crank, transmission, wheels..). I
suppose that the dyno operator has to make a guess of the inertia value of
these parts and add it to the inertia of the cylinders. Here is a comfortable
opportunity for the operator to make the customer happy : if he is adding an
exaggerated number for the inertia of the rotating parts of the car, then the
horsepower is exaggerated. As far as I know , chassis dyno operators never
mention or ask about the car inertia. It would be very interesting though to
know the value he is using, because then you can always use this same value for
runs on different occasions and compare the results a bit better. A chassis
dyno is really only usefull to compare the results of changing things on the
engine during one and the same session.Don't be fooled by the absolute numbers
: Once I went to a chassis dyno with my TR3 : my car must have looked pitiful
against the modern cars the operator was normally testing, because the result
was 210 bhp at the wheels and I knew it surely had no more than 180 bhp at the
flywheel! I don't know if some chassis dyno's have a brake to hold the engine
on a constant rpm at WOT : then the inertia of dyno and car doesn't matter and
you know the right horsepower at the wheels. About right at least : you can
cheat yourself a bit by overinflating the tyres and the dyno has still to be
calibrated rightly.
Marcel
Van: "fot" <fot at autox.team.net>
Aan: "Bill" <Bill at ponostyle.com>, "Larry Young" <cartravel at pobox.com>
Cc: "fot" <fot at autox.team.net>
Verzonden: Woensdag 5 september 2018 02:44:00
Onderwerp: Re: [Fot] 89MM piston question
You mean something like this ? Measured on a chassis dyno. The notes on the
left are the suggested power train loss
as described by the dyno shop. But, whatever the final numbers are in truth the
5250 mark is right there.
This was the comaprison to my 2015 engine spec.
I shouldn?t have advanced that cam me thinks.
jim g
From: Fot <fot-bounces at autox.team.net> On Behalf Of Bill via Fot
Sent: Tuesday, September 4, 2018 3:08 PM
To: Larry Young <cartravel at pobox.com>
Cc: fot at autox.team.net
Subject: Re: [Fot] 89MM piston question
I?m being a bit facetious, I understand what people mean (sort of) but I?ve
heard ?Horsepower wins sales, torque wins races.? and the equivalent spoken or
written sagely, with solemn nods all around, too many times not to comment. One
is a functional equivalent of the other, both in a mathematical and practical
sense. The relationship is linear. Torque is force. Horsepower includes a
circular distance component to express work.
As you say, the numbers for the power and torque curves should equate at every
point (adjusted by the function). The fact that they often don?t is
ridiculous?horsepower measured by a dyno is calculated from torque and RPM, not
directly measured. The shorthand bullshit detector for dyno curves expressed in
Imperial units of ft-lbs and horsepower is to see if the curves cross at 5252
RPM. Many don?t, including those published in car magazines.
Sheesh.
On Sep 4, 2018, at 9:21 AM, Larry Young via Fot < [ mailto:fot at
autox.team.net | fot at autox.team.net ] > wrote:
P = T*R/5252
When people talk about a torquey engine, they usually mean it makes its power a
low revs.
I once ran an engine on two different rolling road dynos (a Dynojet and a
Mustang Dyno. The guys at the dyno shop said the second one would give less hp
because they used a brake in their setup. I said, "you didn't calibrate for
that"? They backpedaled and gave me a line of BS. Then the power and torque
curves they produced did not agree with the equation. To get an explanation, I
worked my way up the chain and eventually talked to the dyno companies head
"technical" guy. He said he thought it must be the calibration! I said, "it is
basic physics, like saying F = ma". Since then, I have never trusted dyno
numbers. Good for comparative tuning runs only and of course, bench racing.
- Larry
On 9/2/2018 10:46 PM, Bill via Fot wrote:
BQ_BEGIN
It always puzzles me when people say that. Horsepower is torque times RPM (and
a conversion factor). Torque is horsepower/RPM. So how can one count more than
the other?
BQ_BEGIN
On Sep 2, 2018, at 4:13 PM, Mordy Dunst via Fot < [ mailto:fot at
autox.team.net | fot at autox.team.net ] > wrote:
Its the torque that counts. So, I suspect the motor enhancements took the
benefit of the tractor stroke. If the motor is able to produce that power at 6k
rpm with shift at 6500.
I shift at @ 6200 - my motor produces max power @5800 on the dyno. I use a
kastner designed cam for which I have the masters.
MDunst [ http://headgasket.com/ | Headgasket.com ] [ tel:626.358.1616 |
626.358.1616 ]
Fax [ tel:626.628.3777 | 626.628.3777 ]
Triple R Munitions, Inc [ tel:626.201.9471 | 626.201.9471 ]
T FFL 6,7 SOT 2
On Sunday, September 2, 2018, John Styduhar via Fot < [ mailto:fot at
autox.team.net | fot at autox.team.net ] > wrote:
BQ_BEGIN
What kind of modifications were done to the engine to extract over 200 HP from
a tractor engine? Nitrous shot.
On Sat, Sep 1, 2018 at 3:05 PM Thomas Boyd < [ mailto:tom at trenterprises.com
| tom at trenterprises.com ] > wrote:
BQ_BEGIN
All of our FIA race cars are running legal 87mm engines.
Just rolling roaded the latest SLR build at well north of 200bhp
Thomas Boyd
Director
TR Enterprises
[ tel:01623%20793807;302 | 01623 793807 (ext 302) ]
[ http://www.trenterprises.com/ | www.trenterprises.com ]
On 1 Sep 2018, at 17:02, John Styduhar via Fot < [ mailto:fot at autox.team.net
| fot at autox.team.net ] > wrote:
BQ_BEGIN
If you really had serious compliance with most group's rules, I would guess
half the TR cars would not pass muster. Let's have fun together.
On Sat, Sep 1, 2018 at 9:40 AM Terry Stetler via Fot < [ mailto:fot at
autox.team.net | fot at autox.team.net ] > wrote:
BQ_BEGIN
Indeed there are Glen.
Sent from [ https://go.microsoft.com/fwlink/?LinkId=550986 | Mail ] for Windows
10
From: Fot < [ mailto:fot-bounces at autox.team.net | fot-bounces at
autox.team.net ] > on behalf of fubog1 via Fot < [ mailto:fot at autox.team.net
| fot at autox.team.net ] >
Sent: Saturday, September 1, 2018 7:34:26 AM
To: [ mailto:rkramer56 at gmail.com | rkramer56 at gmail.com ]
Cc: [ mailto:fot at autox.team.net | fot at autox.team.net ]
Subject: Re: [Fot] 89MM piston question
BQ_BEGIN
everybody else seems to be using 89.
HaHa not everybody, rules say 87mm, there are still a few guys running them
(and winning)...
Glen
-----Original Message-----
From: Bob Kramer via Fot < [ mailto:fot at autox.team.net | fot at
autox.team.net ] >
To: van.mulders.marcel < [ mailto:van.mulders.marcel at telenet.be |
van.mulders.marcel at telenet.be ] >
Cc: fot < [ mailto:fot at autox.team.net | fot at autox.team.net ] >
Sent: Fri, Aug 31, 2018 11:26 pm
Subject: Re: [Fot] 89MM piston question
I've always used 87 MM due to the rules but everybody else seems to be using
89. The procedures are the same so It'll be the same. I blew a head gasket last
time out, compression into the cooling system and blew off the bottom hose. I
guess it wasn't tight enough, and scuffed two pistons before I could shut it
down.
Bob Kramer
On Fri, Aug 31, 2018 at 12:43 PM, < [ mailto:van.mulders.marcel at telenet.be |
van.mulders.marcel at telenet.be ] > wrote:
BQ_BEGIN
Bob,
It is definitely necessary to make that modification to the liners. The relieve
should correspond to the shape of the combustion chambers : about 4 mm wide on
a 89mm engine.
Marcel
Van: "fot" < [ mailto:fot at autox.team.net | fot at autox.team.net ] >
Cc: "fot" < [ mailto:fot at autox.team.net | fot at autox.team.net ] >
Verzonden: Donderdag 30 augustus 2018 00:05:43
Onderwerp: [Fot] 89MM piston question
Do the guys running the 89MM pistons and liners need to relieve the liners to
clear the intake valve, or does the extra MM make the difference?
Bob Kramer
On Tue,
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