TarkMalbot Posted April 11, 2009 Report Share Posted April 11, 2009 I am looking at doing some 1/4 mile drag races and was wondering what I needed to do to set my car up for it. I am using the MX-5 so RWD, I have 250bhp and 235/40/17 Toyo TR-1 tyres. Should I reduce the tyre pressures? And if so by how much? I am currently running 30 PSI. I guess I can try a few different things regarding the traction control and stability control and see what gives me the best times but unsure of tyre pressures. Thanks. Quote Link to comment Share on other sites More sharing options...
scorps Posted April 11, 2009 Report Share Posted April 11, 2009 Wouldn't it depend on the weather and track temps as well as pressures, im sure there will be others you could take advise from once there. Have a great time Quote Link to comment Share on other sites More sharing options...
Tony Posted April 11, 2009 Report Share Posted April 11, 2009 You need maximum contact patch so i would drop the presure to around 15psi. Quote Link to comment Share on other sites More sharing options...
Bazza Posted April 11, 2009 Report Share Posted April 11, 2009 You need maximum contact patch so i would drop the presure to around 15psi. as the most important bit is getting away from the line that is good advice, although the lower pressure will give a bit more drag on the run itself ! not sure as low as 15psi, drop it slowly in stages to see what works best, too low and the tyre can loose contact area in the centre stick the front pressures up to reduce their drag as well remember to inflate/deflate as necessary afterwards ! Quote Link to comment Share on other sites More sharing options...
Rich Posted April 11, 2009 Report Share Posted April 11, 2009 Wouldn't deflating the tyre that much cause more of a strain on it and potentially damage it...thinking of the side wall here? Quote Link to comment Share on other sites More sharing options...
scorps Posted April 11, 2009 Report Share Posted April 11, 2009 Like i said have a word when you get there as you will find people who know about drag racing and can give excellent advise rather that people who think they know whats right. Quote Link to comment Share on other sites More sharing options...
Tony Posted April 11, 2009 Report Share Posted April 11, 2009 I'm just thinking back to my involvement with a funny Drag-car team some years back. The logic was low pressure =maximum contact patch then after launch> centrifugal force distorts the contact patch, which "assuming" the car keeps accelerating will reduce. Quote Link to comment Share on other sites More sharing options...
TarkMalbot Posted April 16, 2009 Author Report Share Posted April 16, 2009 A few guys in the US said similar. 22 in the back and 40 in the front. Thanks for the help. Quote Link to comment Share on other sites More sharing options...
Tony Posted April 16, 2009 Report Share Posted April 16, 2009 A few guys in the US said similar. 22 in the back and 40 in the front.Thanks for the help. It's a "suck it and see" scenario because of all the variables..... test, test and test again is the only way. Quote Link to comment Share on other sites More sharing options...
TarkMalbot Posted April 19, 2009 Author Report Share Posted April 19, 2009 I think it was me who was the problem today not the tyre pressures! My reaction time varied massively, my wheel spin, gear changes etc etc was different every time. With half hour queue between each run my coolant temp and intake temp was pretty high. I did 4 runs in total and other than my reaction time, my last run felt like it went pretty well. No wheel spin, no rev limiter, my fastest 60 foot time, fastest 1/4 time and terminal speed. And to my surprise I have just checked all the cars in the RWD Jap Class and I was 4th Overall only beaten by 3 Nissan 200SX. I managed to see off the Supra, RX7, RX8, Skyline, MR2, LS200 and a J2x90 MkII (whatever one of those is) 1/4 Mile Time: 14.258 sec Reaction Time: 0.972 sec 60 Foot Time: 2.176 sec Maz Speed: 97.6 mph mph Left Lane No prizes for guessing who won here: His was: 1/4 Mile Time: 12.096 sec sec Reaction Time: 0.333 sec 60 Foot Time: 1.873 sec Max Speed: 120.6 mph mph Right lane Quote Link to comment Share on other sites More sharing options...
Tony Posted April 20, 2009 Report Share Posted April 20, 2009 Nice ..... Your reaction times and gear changes will improve in time i should think, and you can't moan when your beating the likes of Supra, RX7, RX8 and Skyline's. Quote Link to comment Share on other sites More sharing options...
TarkMalbot Posted April 20, 2009 Author Report Share Posted April 20, 2009 My gea changes were spot on. I think what let me down was being nervous and flustered on the line as it was my first time. I think my technique was wrong too as I had my clutch fully disengaged. If I was to do it again I would have it on the bite point and hold the car on the hand brake so as soon as the lights changed I could just let off the hand break and be off rather than having to get to the bite point first. Never mind. Quote Link to comment Share on other sites More sharing options...
Tony Posted April 20, 2009 Report Share Posted April 20, 2009 It's a learning curve...... You did well considering and look what what you saw off Quote Link to comment Share on other sites More sharing options...
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