Drag radial head-scratcher
#2564461
10/15/18 04:17 PM
10/15/18 04:17 PM
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Joined: Jan 2005
Posts: 223 California
70Drop
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enthusiast
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OP
enthusiast
Joined: Jan 2005
Posts: 223
California
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I went to the ANRA event this weekend and had a blast! Just put new tires on the car: M/T Pro Drag Radial, 9x30-15. These replaced 10.5x30-15 bias ply slicks. For my first run, I used 16 psi. The tires gave me a 1.65 60'. That was terrible compared to my old tires that gave me a 1.58 typically. Everyone told me to go up in pressure to make them work better, but I instead went down to 12 psi, which was the low end of the recommendation from M/T: http://www.mickeythompsontires.com/tech-bulletins/street-air-pressure-guidelinesAt 12 psi, the car gave me a 1.52 60', which is the best ever with the car. Multiple people said I should go up on pressure rather than down and that if I put 20 psi in the tire, it would do even better. Since I was going into competition rounds, I didn't want to change anything and ignored them. I continued to get great 60' times. The next time I can get some T&T runs, I'm going to try higher pressures to see what happens, but I'm very interested in the experience of you guys. Relevant specs on the car: About 3300 lbs. with me in it Super Stock leaf springs + Caltracs and drag shocks 727 with 3500 stall, 4:10 gears 500" big-block with a 260 @ 0.050 solid roller
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Re: Drag radial head-scratcher
[Re: 70Drop]
#2564471
10/15/18 04:42 PM
10/15/18 04:42 PM
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Joined: Jan 2003
Posts: 8,027 Tulsa OK
Bad340fish
master
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master
Joined: Jan 2003
Posts: 8,027
Tulsa OK
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I run the Pro Bracket Radial in a 28x10.50. Mine has had the best 60ft of 1.41 at 19 psi. In reality it was probably higher, I made 3 passes in 40 minutes and that 19PSI was the cold pressure before the first run.
68 Barracuda Formula S 340
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Re: Drag radial head-scratcher
[Re: 70Drop]
#2564472
10/15/18 04:42 PM
10/15/18 04:42 PM
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Joined: Jan 2003
Posts: 2,917 A shed in England
Tig
master
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master
Joined: Jan 2003
Posts: 2,917
A shed in England
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Pretty new to drag radials myself as I haven't made a full pass yet. We started at 16 psi stone cold, the rear shocks are valved for radials. We were wadding up the bias plys real bad with the shocks set up for radials so I'm guessing you can go with a lot more aggressive settings with Radials. Our second "go for it" pass produced a big wheelstand and the landing did some damage after I lifted. There's some more info in the "tips for a drag radial newby" thread. HTH's
Last edited by Tig; 10/15/18 04:51 PM.
'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials. 9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge. RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
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Re: Drag radial head-scratcher
[Re: 70Drop]
#2564499
10/15/18 05:23 PM
10/15/18 05:23 PM
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Joined: Jan 2003
Posts: 13,363 Marion, South Carolina [><]
an8sec70cuda
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 13,363
Marion, South Carolina [><]
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If the track is good, I've run up to 21 psi in my 295-65 M/T ET Street radials. Typically gets quicker as air pressure goes up.
CHIP '70 hemicuda, 575" Hemi, 727, Dana 60 '69 road runner, 440-6, 18 spline 4 speed, Dana 60 '71 Demon, 340, low gear 904, 8.75 '73 Chrysler New Yorker, 440, 727, 8.75 '90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt '06 GMC 2500HD LBZ Duramax
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Re: Drag radial head-scratcher
[Re: an8sec70cuda]
#2564509
10/15/18 05:45 PM
10/15/18 05:45 PM
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Joined: Jan 2003
Posts: 11,711 Portage,michigan
B3422W5
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 11,711
Portage,michigan
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If the track is good, I've run up to 21 psi in my 295-65 M/T ET Street radials. Typically gets quicker as air pressure goes up. Yep. Dragging less of a flat pair of tires down the track
69 Dart GTS A4 Silver All steel, flat factory hood, 3360race weight 418 BPE factory replacement headed stroker, 565 lift solid cam Best so far, 10.40 @127 1/4 1.41 best 60 foot 6.60 at 103.90 1/8
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Re: Drag radial head-scratcher
[Re: 70Drop]
#2564526
10/15/18 06:21 PM
10/15/18 06:21 PM
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Joined: Mar 2009
Posts: 2,463 Sydney,Australia
tex013
top fuel
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top fuel
Joined: Mar 2009
Posts: 2,463
Sydney,Australia
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what width rear rim ? That will affect psi . Do you have radial valved,tight, rear shocks ? Did you alter rear shock settings going to radials ? What sort of power/ ET ? Whatever works for your car is best . For what its worth , with Hoosier 275 radials I ran 17 1/2 - 18psi on a 8" rim . Similar with MT ET street radials . With MT Pro bracket radials I went to a 10" rim , with the 28x10.5 I ran 18psi , I now run the 29.5x10.5 version @ 19 psi . Looking at launch pics may even prefer another 1/2psi or so .
Oh yeah I was running 1.42-1.48 with my 505 , with my 440 I am around 1.5-1.52
Tex
Last edited by tex013; 10/15/18 06:23 PM.
New best ET 10.259@129.65 . New best MPH 130.32 Finally fitted a solid cam, stepped it up a bit more 3690lbs through the mufflers New World block 3780lbs 10.278@130.80 . Wowser 10.253@130.24 footbraking from 1500rpm Power by Tex's Automotive
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Re: Drag radial head-scratcher
[Re: tex013]
#2564542
10/15/18 07:23 PM
10/15/18 07:23 PM
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Joined: Jan 2005
Posts: 223 California
70Drop
OP
enthusiast
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OP
enthusiast
Joined: Jan 2005
Posts: 223
California
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what width rear rim ? That will affect psi . Do you have radial valved,tight, rear shocks ? Did you alter rear shock settings going to radials ? What sort of power/ ET ? Whatever works for your car is best . For what its worth , with Hoosier 275 radials I ran 17 1/2 - 18psi on a 8" rim . Similar with MT ET street radials . With MT Pro bracket radials I went to a 10" rim , with the 28x10.5 I ran 18psi , I now run the 29.5x10.5 version @ 19 psi . Looking at launch pics may even prefer another 1/2psi or so .
Oh yeah I was running 1.42-1.48 with my 505 , with my 440 I am around 1.5-1.52
Tex They are 10-inch rims. I didn't change the shock settings for the radials. I hadn't thought about that. ET is 10.60 to 10.70. I probably have about 550 hp at the wheels. I didn't realize there was a thread about drag radials. I'll have a look.
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Re: Drag radial head-scratcher
[Re: 70Drop]
#2564586
10/15/18 09:02 PM
10/15/18 09:02 PM
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Joined: Mar 2009
Posts: 2,463 Sydney,Australia
tex013
top fuel
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top fuel
Joined: Mar 2009
Posts: 2,463
Sydney,Australia
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see if you can get startline video or pictures , see what is happening
Tex
New best ET 10.259@129.65 . New best MPH 130.32 Finally fitted a solid cam, stepped it up a bit more 3690lbs through the mufflers New World block 3780lbs 10.278@130.80 . Wowser 10.253@130.24 footbraking from 1500rpm Power by Tex's Automotive
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Re: Drag radial head-scratcher
[Re: 70Drop]
#2564664
10/15/18 11:59 PM
10/15/18 11:59 PM
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Joined: Aug 2003
Posts: 43,174 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,174
Bend,OR USA
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Generally speaking most drag radials like more pressure than any bias ply does, that being said I haven't raced a set of radials in a lot of years so keep that in mind. the last set of legal NHRA stocker bias ply tires I raced on where 9x30 on a ten inch wide rim that ET the best with 16.0 to 17.0 Lbs. cold, the 60 ft. and reaction times where great on those tires Do you know how accurate your tire pressure gauge is? Are you using a low tire pressure gauge or a regular gauge that goes up to 60 Lbs. or more? I've seen decent quality low pressure tire gauges vary a hoop, some read low and some read high compared to a very good known calibrated test gauge I suggest you use your tire gauge only, DO NOT LOAN it out EVER Add air 1/2 lb. at a time until the 60 ft. and reaction times slow down and then go the other way down 1/2 lb/. at a time until it reaches the limits on the low side The number on the gauge doesn't really matter as long it reads the same every time with the same pressure in the tire, what does matter is the time slip
Last edited by Cab_Burge; 10/16/18 12:00 AM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Drag radial head-scratcher
[Re: ross]
#2564686
10/16/18 12:57 AM
10/16/18 12:57 AM
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Joined: Sep 2014
Posts: 4,457 Washington
madscientist
master
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master
Joined: Sep 2014
Posts: 4,457
Washington
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My M&H Racemasters like 21.5 on my car. Which tire are you using?
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
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Re: Drag radial head-scratcher
[Re: Cab_Burge]
#2564708
10/16/18 01:58 AM
10/16/18 01:58 AM
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Joined: Jan 2005
Posts: 223 California
70Drop
OP
enthusiast
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OP
enthusiast
Joined: Jan 2005
Posts: 223
California
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Generally speaking most drag radials like more pressure than any bias ply does, that being said I haven't raced a set of radials in a lot of years so keep that in mind. the last set of legal NHRA stocker bias ply tires I raced on where 9x30 on a ten inch wide rim that ET the best with 16.0 to 17.0 Lbs. cold, the 60 ft. and reaction times where great on those tires Do you know how accurate your tire pressure gauge is? Are you using a low tire pressure gauge or a regular gauge that goes up to 60 Lbs. or more? I've seen decent quality low pressure tire gauges vary a hoop, some read low and some read high compared to a very good known calibrated test gauge I suggest you use your tire gauge only, DO NOT LOAN it out EVER Add air 1/2 lb. at a time until the 60 ft. and reaction times slow down and then go the other way down 1/2 lb/. at a time until it reaches the limits on the low side The number on the gauge doesn't really matter as long it reads the same every time with the same pressure in the tire, what does matter is the time slip Good point. It wouldn't be the first time I've chased a gremlin that turned out to be bad data! My gauge is a low-pressure type, so I'm measuring at the top of the scale for the radials. Same gauge I've used with my old slicks. I think it was pretty accurate, but I should probably use another gauge to compare with
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Re: Drag radial head-scratcher
[Re: 70Drop]
#2564890
10/16/18 03:34 PM
10/16/18 03:34 PM
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Joined: Jan 2003
Posts: 2,917 A shed in England
Tig
master
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master
Joined: Jan 2003
Posts: 2,917
A shed in England
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Valving a rear shock for radial is looser than the equivalent bias ply shock on extension at least.
'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials. 9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge. RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
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