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This is a street car, but I have no problem driving cars with lots
of HP. What do I need to "touch" on the 6 cylinder in order to make
it roar?
Carburation isn't an issue as I have a factory PI setup with multi-port
fuel injection, oxygen sensors and computer controls to drive it
which will go on later. (This setup could actually be Vortex boosted,
but I am dreaming again...)
So, while the engines apart, what needs enhancing? What are its weak
points? Will it handle 7,000 RPM? What mods bring the size to 2.7L
that Rimmer sells, is this a good idea?
Roger_
Where to start...Hey I know, how 'bout an opinion...
Start with the head. Minimum here is to take the "ledges" off each side of
the combustion chamber. You should have a comp prep manual and they cover
that pretty well. I wouldn't go over about .050" off of the head (less if you
do not remove the ledges) as the thing will ping easily. Match the ports to
the manifold, and if you feel at ease doing head work, go ahead and remove
the sharp edge at the lower edges of the port where it goes into the pocket.
Also spend some time opening up the area behind the valve guide. Use bronze
guides. Measure the thickness of the head before you start as there are
several different thicknesses (and of course yours could have been cut
already). Measure from the head gasket face to the rocker cover gasket face
(both machined faces), the stock thickness should be 3.460" on that motor.
To decrease the "pinging" problem, you will want to recurve your distributor.
You may actually be able to advance the thing more than the stock setup, but
you will have to slow the curve down quite a bit. You will probably find that
with the stock tired distributor, all the advance will be in quite early (i'd
guess 2500 rpm or so). Try to set it up so that it is doesn't stop advancing
til about 4000 rpm. All motors are different, and it will take some serious
time to get it down.
Balance the bottom end piece by piece. By that I mean balance all the pistons
the same, all the rods the same, balance the crank, then add the pulley and
balance it, then add the flywheel and balance it etc etc. As you add each new
piece, any metal adding/removing should come only from the newest piece. Use
only a stock pressure plate. The heavy duty ones add additional stress to the
thrust washers and they are a weak link. Go for an aluminum flywheel, its
like free "horsepower". It doesn't really add any power, but it will allow
the motor to rev quicker.
If you are using the factory injection, you can go really wild on the cam
specs. What was a fairly hot street cam on a carburated motor, turned out to
be mild on the injected model. Is this motor an injected one, or are you
adding the stuff?
For exhaust you have two different styles of headers. For street applications
go for the one that combines three cylinders into two, then combines the two
pipes into one. If you can lose a little power below 3500 rpm or so, but make
it up above that rpm, go for the header that combines all six pipes into one
directly. No matter how nice it sounds with two, use only one exhaust pipe
all the way back, it makes the most power. If this thing is gonna be
"pumped", I would try 2.5" pipe all the way back, but you probably won't lose
too much at 2.25".
I hope you don't mind, but I'll throw this out on the list as I'm sure it
will be a good topic, and and everyone who knows that I'm all wrong, will
want to jump in here. You'll get lots of opinions ! <g>
Never one to hold back on my opinion...
Nick in Nor Cal
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