Blue line is what i see most of the time. Red line was a later in the night pass, that the car picked up a ton in 60'. Trying to figure out how to keep the red line all the time, or keep the blue line more consistent. Sometimes the hump is longer and it slows the et down. This is aprox. .4 into the run. Is the tire wadding up from not enough PSI?

More info needed. Also are you running Hoosiers?

M/T 3074S 10.25 PSI 2475# 4link, DA Strange, 6 on C, 2 on R, 110# spring.

where is i/c, what are springs set at.i assume the track got better on red line.are you pulling timing,what is hp

just saw the shock settings try going to 8 on rebound(not sure on total number of clicks)

One more click on compression and it feels as the car bounces like it is too stiff then. Not sure on IC, strut car and it picks the wheels up just about 3 or 4 inches and carries them 10 ft or so. I have pulled 6 degs at hit, and none and shows no difference in et or DS rpm.

I may be wrong but that seems like alot of air for that weight of car.

quote:

Originally posted by BLIND MULE 2217:
I may be wrong but that seems like alot of air for that weight of car.

Its been a while since I've been that light, but the air pressure does seem way high....

Have you tried any passes with less air? I also found having someone record run with an I pad at a good angle lets me see a lot in super slo-mo. Had similar issue with dragster and air pressure helped a lot.

quote:

Originally posted by BLIND MULE 2217:
I may be wrong but that seems like alot of air for that weight of car.

I'm running 8.5lbs at 2003lbs so I don't think he is too high.

Does it hit the wheelie bars?

I have run lower when I first switched to MT but pics/videos showed it really wrinkling the tire.

Wheelie bars? What wheelie bars? LOL Its a strut car so it only carries the wheels up about 3 or 4 inches id say and for only about 10 ft or so?

quote:

Originally posted by Slick Vic:
I have run lower when I first switched to MT but pics/videos showed it really wrinkling the tire.

Wheelie bars? What wheelie bars? LOL Its a strut car so it only carries the wheels up about 3 or 4 inches id say and for only about 10 ft or so?

Have you tried playing with the strut adjustment any, How are they set?

Struts are all the way loose.

quote:

Originally posted by Slick Vic:


Blue line is what i see most of the time. Red line was a later in the night pass, that the car picked up a ton in 60'. Trying to figure out how to keep the red line all the time, or keep the blue line more consistent. Sometimes the hump is longer and it slows the et down. This is aprox. .4 into the run. Is the tire wadding up from not enough PSI?

I will also add this, forgetting the spin hook blue line deal, the red graph is a bus load higher than the blue indicating much higher WS and therefore much better performance! So you have more going on here than just traction if the actual air change is not that great! or you are not factoring in the air change vs on track performance correctly.

quote:

Originally posted by TOP38:
I will also add this, forgetting the spin hook blue line deal, the red graph is a bus load higher than the blue indicating much higher WS and therefore much better performance! So you have more going on here than just traction if the actual air change is not that great! or you are not factoring in the air change vs on track performance correctly.

Not much air change, a little better, but sun off of track at this point so I am sure the track got better. So is the tire "wrinkled" and staying that way on that pass and not on the blue line pass? Then less air would be better?

quote:

Originally posted by Slick Vic:

quote:

Originally posted by TOP38:
I will also add this, forgetting the spin hook blue line deal, the red graph is a bus load higher than the blue indicating much higher WS and therefore much better performance! So you have more going on here than just traction if the actual air change is not that great! or you are not factoring in the air change vs on track performance correctly.

Not much air change, a little better, but sun off of track at this point so I am sure the track got better. So is the tire "wrinkled" and staying that way on that pass and not on the blue line pass? Then less air would be better?

Your missing my point, they should be laying over each other almost exactly! Unless you have a large air swing, the HP is not impacted to any real degree to cause that large of a WS difference, your red line is higher everywhere (other than the spin portion) in that graph which indicates more power is being applied to the tires! and it is showing you that on your time slip too.

In general more air pressure, more bite....

I am having the same issue with my car. Goes out about 4 to 5 feet and spins. I was pulling timing and trying to detune the car and in talking to some other racers they feel I am not hitting the tire hard enough to stay up on the tire. Wheel speed is only about 400 to 450 at .25 out.

I am going to change my gear from a 4:86 to a 5:27 with a 1.80 first gear, which will be a 9:5 to 1 starting line. For my weight (2650 lbs.) and stroke (421 SBC). Also looking at going from a 5400 stall to around 6000 to get up in the range of the cam.

I lose about .02 to .03 when it spins...

To me, it looks like you are "basketballing" the rear tire. If the tire is wrinkling hard with that air pressure and weight, you may be hitting the tire too hard on the initial hit. The graph seems to show the initial hit is squashing and wrinkling the tire hard (hence the small spike), then it hooks for a period of time, then the tire rebounds (unloading the tire) and spins. I would try tightening the rear shock extension to see if the issue gets better. If it does, you can continue to tighten the shock extension or make a 4 link adjustment to take out a little hit.

Hope this helps.

quote:

Originally posted by TOP38:

I will also add this, forgetting the spin hook blue line deal, the red graph is a bus load higher than the blue indicating much higher WS and therefore much better performance! So you have more going on here than just traction if the actual air change is not that great! or you are not factoring in the air change vs on track performance correctly.

Sorry to disagree but the relationship between the curves tracks steady throughout the screen shot. The discrepancy between the two is not performance related, the ground lost on the initial spin is the culprit.

quote:

Originally posted by RyanNorton1:

quote:

Originally posted by TOP38:

I will also add this, forgetting the spin hook blue line deal, the red graph is a bus load higher than the blue indicating much higher WS and therefore much better performance! So you have more going on here than just traction if the actual air change is not that great! or you are not factoring in the air change vs on track performance correctly.

Sorry to disagree but the relationship between the curves tracks steady throughout the screen shot. The discrepancy between the two is not performance related, the ground lost on the initial spin is the culprit.

You can disagree all you want. We all have opinions!