Drag Radial Theory Question

[ViperTruck2933]

I ran the M&H 390s with 4.56 gears and just barely ran out of rpm (rev limiter) in 4th gear. I had the tires lowered down to 20 psi.

If I air them back up to 30 or so psi, will the tire be taller and help me get to the traps with a little rpm left?? :dontknow:

 

[TheMoparConnection]

i dont think you'll gain that much gear. I'm a couple hundred rpm away from redline myself. I like the stock tire size with my mods and next week the truck gets the cam and taller slicks. Excited to see the change.

 

[Dave T(BADVENM)]

i dont think you'll gain that much gear. I'm a couple hundred rpm away from redline myself. I like the stock tire size with my mods and next week the truck gets the cam and taller slicks. Excited to see the change.

What size will these be? Are you gonna run a true slick or taller drag radial?

 

[Nowwhat]

I ran the M&H 390s with 4.56 gears and just barely ran out of rpm (rev limiter) in 4th gear. I had the tires lowered down to 20 psi.

If I air them back up to 30 or so psi, will the tire be taller and help me get to the traps with a little rpm left?? :dontknow:

talk to Joe and see if with your rocker gear....if you can raise the rev limiter

 

[TheMoparConnection]

taller slick

 

[TheMoparConnection]

talk to Joe and see if with your rocker gear....if you can raise the rev limiter

good idea:idea:

 

[ViperTruck2933]

talk to Joe and see if with your rocker gear....if you can raise the rev limiter

Good idea, but won't work. My hp and trq fall completely off the table at 5800 rpms.

My limiter is already raised with the DC Stage II computer that I am running with the VEC 2. I have to shift at 5700-5800.

 

[ViperTruck2933]

What I REALLY need is a taller drag radial.

 

[AWDisuzu]

you only run over 5800 rpm in 4th to avoid going to 5th. you should still shift normally in other gears. you would need a considerably taller sidewall to make a noticeable difference in top speed rpm. I have a neat little program that calculates your 1/4 mile time based on a bazillion variables you type in. I'll see what I can figure out for ya.

do you have a dyno chart or at least HP/TQ numbers?

 

[Nowwhat]

What I REALLY need is a taller drag radial.

thats true....keep in mind at the end of the run.....trq falling off is no big deal as you are already hauling ass....my point is 100 rpm may give you what you need without more $$....let me grab the website...

 

[Nowwhat]

here you go....6000 rpms gets you 115mph

http://www.fordmuscle.com/calculators/rpm.shtml


6000 is no problem for your motor....dial it up...problem solved

 

[westmintrans]

Actually it could go either way. On out test dragster we actually killed 100 rpms on the top end by letting out 1/4 lb of tire pressure (6 psi to 5.75). True the tire is taller but when you run lower tire pressure, you put more load on the engine, thats why they recomend to check your tire pressure to help out your mpg on the highway. And we all know more load = less rpms. So you would have to put your theory to test to actually find out.

 

[Stanimal]

my advise would be to raise the rev limiter to about 6150 so that you dont have to shift into 5th, you will still keep the same ratio's so the 60' times will be about the same. just my .02

 

[TheMoparConnection]

here you go....6000 rpms gets you 115mph

http://www.fordmuscle.com/calculators/rpm.shtml


6000 is no problem for your motor....dial it up...problem solved

thats sounds right i trap at 112.98. and am almost to red line 5900rpm

 

[ViperTruck2933]

I am walking a fine line on the shifts. On my first Drag Radial run (12.57@111mph) I shifted at about 5700 rpms on all shifts and I bumped the limiter before I hit the traps (my limiter is already raised by the Stage 2 PCM).

I made a second pass and shifted all shifts at about 5900 rpms. My ET went down to 12.66@111mph and I barely cleared the traps at 6000 rpms in 4th gear. I think my ET suffered because I revved out of the power band on the early shifts.

I didn't get a chance to make any more runs. Next time out I plan to shoot for 5800 rpm shifts at each gear (top of my power band) and hope I get to the traps. I was just wondering if airing the tire up would help me any. ANY help would be good, becuase I am RIGHT on the line of making it.