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Discussion Starter #103





Some Winter mods to the aero on the yellow machine, extended the front air dam and reprofiled and strengthened the rear spoiler. Also put the car on the RR and saw 205 bhp at the flywheel, added the NOS and saw 275 bhp, giving me just over 400 bhp/ton. Took 3 of us sitting in the car to stop the wheelspin on the rollers :shake:
 

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Discussion Starter #107
The AFR was around 13, dropping to 11 with the NOS on, I wasn't using the bottle heater so a bit more gas to come there.
 

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Discussion Starter #111
Bored now, thinking about the car bouncing around off the line, I wondered if it was some form of tyre shake. Also looking at the numbers, I think the car is overgeared, so fitted a pair of these, 205/60/13 Toyo 888, just as wide as the slicks, sticky, but crucially 8% lower diameter. If I can improve the early track acceleration I could finish up with better overall times but lower trap speed so avoiding the need for an extra shift.


 

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Worth a try Steve.....when the track is finally open again....I did find that my Sprite was very sensitive to tyre pressure to avoid bouncing.
 

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Discussion Starter #113
Ah that's interesting Phil, what sort of tyres/pressures were you running? BTW Martin Cowell's son Mark got in touch and we have exchanged much useful information, in fact that is what got me thinking down this route. Martin ran some amazing times/ ETs but all off quite modest 60 ft times.
 

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Discussion Starter #114

Went to Santa Pod yesterday to do some test and tune. Came home with a best of 11.9 secs @ 114mph, and a 1.7 sec 60ft. Well pleased with that, the new tyres do what I hoped they would.:D
 

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Discussion Starter #116
Yes Robert, the pic is of the car bouncing around on slicks, but with the 888s on it was fast and smooth.
 

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Yes Robert, the pic is of the car bouncing around on slicks, but with the 888s on it was fast and smooth.
slicks can be tricky with smaller engined manual cars. You need lots of torque to keep it planted and hooked up. The see-saw bouncing is all in the tyre sidewall, so you'll struggle to dial it out with 4 link and shock adjustments. Running a stiffer sidewall tyre like you have or more pressure in the slicks should help but its a fine balancing act between traction and wheel speed. It's a moving target based on track temp and prep levels but it helps to collect and record data from your clean full pass runs if you don't already, basic stuff like ambient temp, track temp, tyre pressure, shock settings etc.
 

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Discussion Starter #120

So back to the Pod for another private test day, track was super sticky just after the Euros. Ran a 1.64 second 60 ft but couldn't convert it to an ET better than the 11.9 I ran before. Is it possible that the sticky track holds back a relatively low powered car? More probably the driver not shifting fast enough,,,:shake:
 
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