In a message dated 9/6/2005 12:34:58 PM Eastern Daylight Time, tphy@bmi.net
writes:
Lynn, I just picked up a 91 rx-7 with a frozen engine. My intent is to
turn it into one mean autocross , hillclimbing racer. Where do I start? Is
there a web site for this madness. I'm looking for tons of low end torque (I
think, I am using my stock 91 convertible now, and it's lacking in this
department) Any help would be most appreciated! Also, I need new street tires
for the convertible, something that would be good on wet roads, any
suggestions? Thanks in advance, Tom in Central OR ( also putting a
rotary in my RV-7)
Is this a NA engine?
The rotary is lacking in low end torque. Not that the big car version has a
20B engine (three rotors). It has a generous redline in stock trim, and any hope
of HP production requires a trip to RPM ville. The street engines can take
bursts a bit above the red line without damage.
There are a number of items that make a big difference for little
money.
A big streetport (this all depends very much on the end use of the car) if
street driven to the events. The primaries are cleaned up but timing is left
stock. So, when on the street at normal speeds there is nothing going on but a
stock engine. Then you port the hell out of the secondaries (the big end ports)
so when the revs get high enough to open the secondaries, you have some real
good power. This strategy is also good on gas mileage.
You can also bridge port the secondaries for more of the same effect. This
also lets you maintain a near normal idle. For race only stuff you bridgeport
the whole thing. No low end at all. Not much power until 6,000 RPM, then hang on
Nellie.
Need 100 PSI of oil pressure, a baffle between the pan and engine to keep
the pickup covered. (a good idea for any rotary racer). Best power will be above
9,400 RPM. Aftermarket one piece seals (carbon). Cut the rotor tips down .015"
to keep them off of the irons during crank flex. Scrape off the indium from thr
first 1/8" of the rear stationary gear. Race rotor bearings. Aftermarket
header with freeflowing muffler. Timing at 25-27 degrees fixed both leading and
trailing. Put the muffler under the rear bumper or it will melt.
I have two tube frame race cars, but no street Mazdas. I don't even know
what size tires they use. Sorry.
Lynn E. Hanover