Tested M&H Racemaster Drag Slicks, 7.5 x 23 -15, mounted on 15x6 Malibu alloys.
I was hoping these slicks would solve all my traction problems, and while they did better than my very much used BFG drag radials, I expected more out of a true "slick."
Inner tubes are "recommended" for this type of slick. But neither Jeg's where I bought them or the M&H rep at Coker Tire knew where I could get some that small. So I followed their advice and rubbed dishwashing soap on the inside of the tires, which would seep into any porous spots, and ran 'em tubeless. Had no issues losing pressure, at least not today.
I was surprised to find out these tires are directional. It could have something to do with the inner part of the tire where it seals to the rim, I'm not sure. They are amazingly light at about 16 lbs., making the wheel/tire combo about 31, 9 lbs less than my stock Alero GLS's.
Since the tires are only 23 inches in diameter, the effective drive ratio is drastically changed, and I think I was actually into 4th gear by the end of the track, but I'll have to recheck that.
There were some issues not related directly to the tires that affected the E.T's--high humidity, storms moving through, throttle body limitations, etc. But the times were very consistent, and the launches were all straight. And I hope to learn more the next time out.
Test and Tune, May 7, '08 (Bandimere Speedway) (Elev. 5860 ft, temp. 60-65 deg. F.)
Stock LS1 MAF, 2.5 in. throttle body, iced intercooler, 1.9 in. SC pulley, 11-12 lbs boost. IAT sensor in intake manifold.
1) 14.058 @ 97.70, 2.077 60 ft.
IAT 73-84 deg. / ECT 190-201 deg.
18 psi tire pressure, launched at 1607 rpm. Had air filter and muffler installed on this run; hooked up good--just a couple chirps off the line.
Injector Duty Cycle, 101 %
Bypassed air filter, removed muffler:
2) 14.026 @ 98.81, 2.139 60 ft.
IAT 70-81 / ECT 190-199
18 psi tire pressure, launched at 1576 rpm. Some wheelspin but no sideways movement....
Injector Duty cycle 107 %.--Note how the fuel demand increased after the air filter and muffler were removed.
3) 13.890 @ 99.65, 2.125 60 ft.
IAT 64-75 / ECT 190-198
18 psi tire pressure, launched at 1338 rpm. Same as above....
Injector Duty Cycle, 108%
4) 14.019 @ 98.09, 2.121 60 ft.
15 psi tire pressure. Forgot to save scan....
5) 14.059 @ 98.80, 2.098 60 ft.
IAT 70-82 / ECT 198-201
15 psi tire pressure, launched at 1161 rpm .
Injector Duty Cycle 106%
6) 13.936 @ 99.09, 2.097 60 ft.
IAT 63-77 / ECT 199-205
15 psi tire pressure, launched at 1418.
Injector Duty cycle 107 %
245 timeslips and counting.......
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