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Old 09-25-2016, 10:24 AM
Cobra #3170 Cobra #3170 is offline
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Default Why running 3170 for top speed is a bad idea

Quote:
Originally Posted by MAStuart View Post
Hi Bruce Any idea what your car would run in the quarter mile. I am trying to get a handle on what my sons car would run for top speed if you could drive it to top speed. His car is #3400 pounds 122 cubic inches. It runs 141 in the quarter in 3rd gear. Not sure of rpm but I think 7300. He usually shifts at 9500. Car is a 90 eagle talon 5 speed.

Mark
Hi Mark,
I have no idea about 1/4 mile speed or time back in the early 90's I had a 565 HP (flywheel) tunnel port @ 2450 lb. I took it to Detroit dragway and it ran 128 MPH in 11.24 with a 1.9 60 foot on treaded race tires. The car weighs 2350 now and flywheel HP is around 850 @7600. Traction is better but certainly not anywhere near what a good drag or cheater slick could provide.

Yesterday we were testing 19" Bridgestone 305x30x19 RE-71's vs BFG
Rival 335x30x18 at a Porsche club autox. I changed the linkage on the throttle body to slightly open the secondaries to challenge the tires.
We ran the Rivals in the morning and were not happy with them at all.
After some chassis tuning we got down to respectable time but neither of us liked the feel of the car. In the afternoon we swapped in the Bridgestone's and Scott took 2 runs, they seemed better although times were only slightly better. Now to the point of this long and boring story on his third run just after a shift to second gear the car sheared the stub axle inside the LH rear hub carrier. The wheel would have come off the car because it is retained by a bolt on the other side of the break the only thing that kept it in was the break caliper. That was very scary because the wheel was only loosely located by the outer hub carrier bearing. The stub axles are original and 51 years old, one of the few parts I have never replaced. I am surprised because they are very robust parts but have suffered years of pounding. If this had happened at high speed the car would likely have flipped.
I plan on replacing both stub axles and all the bearings and seals.
The only good news: we were faster than a 991 Porsche GT3 that was on Hoosier A7's and we were the fastest car there on street tires. I will need to replace the rear disc and hat too because they were damaged by the wheel trying to leave the scene.

Last edited by Cobra #3170; 09-25-2016 at 10:29 AM.. Reason: spelling
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