[For those of you who don't know, I sold my 2006 4.0L/5spd coupe, and put most of the hop up parts on the wife's 2005 4.0L/auto vert.]
On Monday I attended a private track rental at MIR with 12 other Mustangs. I was driving our 2005 4.0L/auto ragtop, which is strictly bolt-ons with a 7.5" 4.10's, LSD, LCA's, alum DS, tune, CAI, and alt pulley. I bolted up my 275/50R17 M&H DR's (28" dia) and made 8 passes. I adjusted my timing with the 93 tune, having added 4 gallons of 104 unleaded; played around with shift pressures, and shift points. I would stall up to 1800-2K, and I made several 15.0xx passes with my 60's around 2.15, but my speeds were down a few MPH's over my only other time at the track with this car.
I pulled off my DR's to give two other guys a try with them, and decided to make some runs with my 275/50R17 Nitto NT450 street tires (also 28" dia). Leaving at idle, I immediately knocked off 2/10th and gained 1mph. I ended up with a best ET of 14.779 @ 91.66mph with a best 60' of 2.106.
Although both sets of tires are shown to have the same rotations per mile, I did notice a difference through the traps. With the DR's, I was going through the traps in 4th gear, but with the street tires the car would shift into overdrive at about 4,800 RPM's just before the traps (don't give me too much crap about being in overdrive - I'm used to racing stick shifts). My best runs were on streets with the OD off. So the DR's are a tad bit taller than my street tires (perhaps they're growing slightly in dia as the speed increases?).
So why was I so much better with my streets than the DR's? Track prep was the best I've ever seen. Folks were dead hooking like they've never done before. Could the stickier track been holding my DR's back? Why didn't my 60's decrease with the DR's?
Thoughts?
On Monday I attended a private track rental at MIR with 12 other Mustangs. I was driving our 2005 4.0L/auto ragtop, which is strictly bolt-ons with a 7.5" 4.10's, LSD, LCA's, alum DS, tune, CAI, and alt pulley. I bolted up my 275/50R17 M&H DR's (28" dia) and made 8 passes. I adjusted my timing with the 93 tune, having added 4 gallons of 104 unleaded; played around with shift pressures, and shift points. I would stall up to 1800-2K, and I made several 15.0xx passes with my 60's around 2.15, but my speeds were down a few MPH's over my only other time at the track with this car.
I pulled off my DR's to give two other guys a try with them, and decided to make some runs with my 275/50R17 Nitto NT450 street tires (also 28" dia). Leaving at idle, I immediately knocked off 2/10th and gained 1mph. I ended up with a best ET of 14.779 @ 91.66mph with a best 60' of 2.106.
Although both sets of tires are shown to have the same rotations per mile, I did notice a difference through the traps. With the DR's, I was going through the traps in 4th gear, but with the street tires the car would shift into overdrive at about 4,800 RPM's just before the traps (don't give me too much crap about being in overdrive - I'm used to racing stick shifts). My best runs were on streets with the OD off. So the DR's are a tad bit taller than my street tires (perhaps they're growing slightly in dia as the speed increases?).
So why was I so much better with my streets than the DR's? Track prep was the best I've ever seen. Folks were dead hooking like they've never done before. Could the stickier track been holding my DR's back? Why didn't my 60's decrease with the DR's?
Thoughts?
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