MPH Drop / Tire Size
#1
12-09-2004, 11:37 PM
Join Date: Apr 2004
Location: Plano, Tx
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MPH Drop / Tire Size
Hello,
Took the L to the track this past weekend and I have a few questions reguarding tire size vs. mph loss.
My race setup on the truck consists of running 16x8's in the front and 16x10's in the rear. Both tires are 26" tall and so I was forwarned that I would mostly likely be going through the traps in OD. So for my first run I didn't turn OD off just to see. Well everyone was right! At about 75 yrds before the traps the car went into OD yet still ran my best time (12.5@109). Click here for video. Watch for the puff of exhaust near the end of the run. That's when it goes into 4th The truck totally nosed over when it went into OD like I expected it would and so for the next run I would hold it out in 3rd to see if it could make it and to hopefully better my et and mph.
I had a little worst 60ft on the 2nd run vs. the first pass, (1.79 vs 1.76) my 1/8 mile times were both 8.0@86, but at the end of the track I was able to pass through the traps right at 5,500rpms in 3rd which netted in a 12.6@106mph.
My question is how did I loose 3mph??? Was I getting out of my power band at all?? I should have done another run but I had to leave early and didn't have time. Both runs were made with the coolant being at the exact same temp as well as the air temp outside and so I don't think heat had anything to do with it.
Any suggestions??
BTW, those Mickey Thompson Drag Radials HOOK :d
Thanks.
Took the L to the track this past weekend and I have a few questions reguarding tire size vs. mph loss.
My race setup on the truck consists of running 16x8's in the front and 16x10's in the rear. Both tires are 26" tall and so I was forwarned that I would mostly likely be going through the traps in OD. So for my first run I didn't turn OD off just to see. Well everyone was right! At about 75 yrds before the traps the car went into OD yet still ran my best time (12.5@109). Click here for video. Watch for the puff of exhaust near the end of the run. That's when it goes into 4th The truck totally nosed over when it went into OD like I expected it would and so for the next run I would hold it out in 3rd to see if it could make it and to hopefully better my et and mph.
I had a little worst 60ft on the 2nd run vs. the first pass, (1.79 vs 1.76) my 1/8 mile times were both 8.0@86, but at the end of the track I was able to pass through the traps right at 5,500rpms in 3rd which netted in a 12.6@106mph.
My question is how did I loose 3mph??? Was I getting out of my power band at all?? I should have done another run but I had to leave early and didn't have time. Both runs were made with the coolant being at the exact same temp as well as the air temp outside and so I don't think heat had anything to do with it.
Any suggestions??
BTW, those Mickey Thompson Drag Radials HOOK :d
Thanks.
Last edited by In Flames; 12-09-2004 at 11:39 PM.
#2
12-10-2004, 08:42 AM
Senior Member
Nice looking truck and that's a pretty good Vid too!
I'm running similar ETs and never let it go into OD. (see my web page for the 26" tall tire slip)
There is an old school "rule of thumb" I've always gone by. Ideally you'd hit your max rpms at about the 1220ft mark.
Going into OD right before the line will only serve to shorten the tranny life and slow ETs.
I suspect you went slower because of the core temp of the motor. Even though your coolant temp guage showed the same temp... that does'nt mean the cylinder fill is as dense.
These things are very sesitive to the core motor temp. Much more so than a NA motor.
Rich
I'm running similar ETs and never let it go into OD. (see my web page for the 26" tall tire slip)
There is an old school "rule of thumb" I've always gone by. Ideally you'd hit your max rpms at about the 1220ft mark.
Going into OD right before the line will only serve to shorten the tranny life and slow ETs.
I suspect you went slower because of the core temp of the motor. Even though your coolant temp guage showed the same temp... that does'nt mean the cylinder fill is as dense.
These things are very sesitive to the core motor temp. Much more so than a NA motor.
Rich