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
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