What rml said. The jump to power levels routinely seen in the average
modern Japanese sedan engine entails working around three or four basic
design problems in the TR6 engine. Horsepower costs with these old
girls. That's why I'm going the conversion route for my hotrod (if I
ever get to it).
Luckily, they are fun (and probably safer) as they are.
My personal list would look like Robert's, except for number 3. I might
go with a light hand port on the head and good valve job instead of the
flywheel. I'm not a racer or autocrosser, so I don't have personal
experience with light flywheels on TRs. I'd ask Robert how light to
go..... too light a flywheel can make a car a pain in stop and go
traffic.
The other thing to remember is that every improvement will spotlight the
next weak link in your car, i.e. rear hubs, diff, handling , brakes,
cooling, etc, etc.
Have fun, but don't go nuts!
Jim
----- Original Message -----
From: "Robert M. Lang" <lang@isis.mit.edu>
To: "Sally or Dick Taylor" <tr6taylor@webtv.net>
Cc: "Pim Alferink" <p.alferink3@chello.nl>; <6pack@autox.team.net>
Sent: Monday, April 29, 2002 11:51 AM
Subject: Re: More power
> Hi,
>
> I wanted to chime in on this one... it was too compelling to read "I
want
> to leave the stock manifold apperance" and not reply.
>
> Sadly, if you do not change the exhaust manifold, you might as well
not do
> _any_ mods to your car. If you can't get the spent gasses out the back
in
> an efficient matter, it simply deos not matter what cam, carbs,
> compression or whatever you do to your engine internally. Yes, you
will
> increase the power - no, you will not get all the potential from the
> "system".
>
> I have played with the numbers a lot, and without a free-flow
exhaust -
> forget about making any real power.
>
> I still stand with:
>
> 1. make it breath in (k&n's or whatever)
> 2. make it breath out (a _real_ header, Monzas need not apply - and a
free
> flow exhaust (single 2.5 inch pipe all the way back).
> 3. lighten the flywheel
> 4. reduce the effective gearing with lower profile tires
> 5. dump the crank-driven fan and "go electric".
>
> Doing just these things, you will get a stock TR6 from around 18 secs
on
> the 1/4 mile to under 17 secs.
>
> If you want to turn insane RPM's, then balance. Insane means more than
> 5500 on a stock motor (not balanced). Remember that the inertial
forces of
> only a few grams adds up to hundreds of pounds of force at high RPMs.
>
> If you want to make power, then play with the head. Power means more
than
> 150 HP at the flywheel.
>
> If you want to make "real power", then you can change the cam,
compression
> etc. but your car will not be reliable until you do some stuff to the
> bottom end. For example, the S2 cam with 10:1 can make something like
140
> HP. Move up to 12.5:1, and you get over 160 - BUT the stress on the
rods
> is very high and reliability wil be in question. Numbers are from the
Comp
> Prep. Mnaual.
>
> Anything more tham 9.5:1 on the street is begging for trouble.
>
> The increase in cost to go from basic external changes to fairly
simple
> internal changes is a very big jump. Figure under $1k for items 1 - 5.
Get
> inside the motor and your costs go to 2K +. That's a big jump. And if
you
> do not know what you are doing inside the motor, you will probably
have to
> re-do one or more steps. This will cost you repeatedly 'till you get
it
> right.
>
> If you want details, I can show you several bad cams and broken misc.
> parts (like a cracked crankshaft) from my attempts.
>
> ta-ta,
> rml
> ----------------------------------------------------------------------
--------
> Bob Lang Room N42-140Q | This space for rent
> Consultant MIT unix-vms-help |
> Voice:617-253-7438 FAX: 617-258-9535 |
> ----------------------------------------------------------------------
--------
|