Swapped drag radials to Bias ply-- lost 5mph?
08-20-2012, 11:40 PM
#1
Burning Brakes
Thread Starter
Swapped drag radials to Bias ply-- lost 5mph?
Last fall, I took my car to the track a few times and made 7-8 passes with it on MT 275/60/15 Drag Radials. My car only made 386rwhp/406rwtq, weights 3460lbs with me in it, and it was a 4speed with 3.73gears. I ran low 12s to high 11s. mph 113-116... I played with launching rpm and shift pts, but managed to improve with each run.
My Best w/drag radials
60ft 1.752
330 4.989
660 7.659
MPH1 91.46
1000 9.973
1320 11.930
MPH2 115.12
I hit 116.2mph on another 11.98 pass.
I took the car to the track on opening day this year (back in April) and the 4speed broke and the case split in half on the first launch. I had the car apart for few months and swapped in a liberty gear built tko 600 5spd trans which is faceplatted and set up for drag racing. I went with centerforce dual friction clutch and 25lb centerforce billet steel flywheel. I also redid my fuel system, installed a fuel cell with sump, aeromotive electric pump with -10an lines and aeromotive reg. I swapped my stock seats for a super light weight Kirkey seat, and changed from MT drag Radials to Hoosier 28x11.5x15 quick time pros. I was told that bias ply drag tires are a better match for stick shift cars because they absorb some shock and are easier on drivetrain parts. I was also told they hook better once you figure out what pressure and rpm to run.
Just made it out to strip with new set up and ended up running slower times and also lost mph? I run 13.16, 12.26,12.208,12.100.....and my mph was 110-111mph. On my fastest pass of the day I did reach a new best for 60ft though.
Best pass
60ft 1.699
330 4.973
660 7.733
MPH1 89.31
1000 10.09
1320 12.109
MPH2 111.62
was fun to get car back to the track but I feel like I took a step backward a little bit. However I was shifting easy this time... and trans is built for powershifting.
My goal is to get closer to 11.50s and i ended up run slower and not even getting back into the 11s. Also i dont know why my mph is down. Will a change from radials to bias ply cause a change in mph? My 5speed is geared up slighty diff then the 4speed st10 i had before could take cause the change.
My Best w/drag radials
60ft 1.752
330 4.989
660 7.659
MPH1 91.46
1000 9.973
1320 11.930
MPH2 115.12
I hit 116.2mph on another 11.98 pass.
I took the car to the track on opening day this year (back in April) and the 4speed broke and the case split in half on the first launch. I had the car apart for few months and swapped in a liberty gear built tko 600 5spd trans which is faceplatted and set up for drag racing. I went with centerforce dual friction clutch and 25lb centerforce billet steel flywheel. I also redid my fuel system, installed a fuel cell with sump, aeromotive electric pump with -10an lines and aeromotive reg. I swapped my stock seats for a super light weight Kirkey seat, and changed from MT drag Radials to Hoosier 28x11.5x15 quick time pros. I was told that bias ply drag tires are a better match for stick shift cars because they absorb some shock and are easier on drivetrain parts. I was also told they hook better once you figure out what pressure and rpm to run.
Just made it out to strip with new set up and ended up running slower times and also lost mph? I run 13.16, 12.26,12.208,12.100.....and my mph was 110-111mph. On my fastest pass of the day I did reach a new best for 60ft though.
Best pass
60ft 1.699
330 4.973
660 7.733
MPH1 89.31
1000 10.09
1320 12.109
MPH2 111.62
was fun to get car back to the track but I feel like I took a step backward a little bit. However I was shifting easy this time... and trans is built for powershifting.
My goal is to get closer to 11.50s and i ended up run slower and not even getting back into the 11s. Also i dont know why my mph is down. Will a change from radials to bias ply cause a change in mph? My 5speed is geared up slighty diff then the 4speed st10 i had before could take cause the change.
08-20-2012, 11:50 PM
#3
Race Director
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Any weather data? Your good passes were last fall...and I'm guessing it's a good bit warmer now? How about humidity, headwinds etc?
Bias Ply slicks will often be slower than radials by a MPH or so....but they obviously worked with the improved 60' even with the greatly increased first gear ratio.
JIM
Bias Ply slicks will often be slower than radials by a MPH or so....but they obviously worked with the improved 60' even with the greatly increased first gear ratio.
JIM
08-21-2012, 09:46 AM
#5
Safety Car
Could be a combination of factors for the slower runs, weather conditions, state of tune (fresh spark plugs needed maybe), etc. But I experienced the same thing (worse runs) when trying a set of ET bias slicks. The MT ET Drag Radials have less rolling resistance than bias ply tires. They also work better with the C3 suspension; no flexing or ballooning on the top end. I ended up selling the slicks and putting the Drag Radials back on, and the performance was back to normal.
08-21-2012, 09:57 AM
#6
Race Director
From a technical point of view I can see the bias ply tire absorbing the shock/hit from a 4 speed, so instead of the shift being transferred to the pavement some is energy is absorbed in the tire itself so can see where some MPH and ET could be lost in the change. Off the line they should be the same or little quicker due to the better launch you will get once the sidewall straightens back up 
08-21-2012, 12:24 PM
#7
Race Director
I can't tell how well you're hooking because the vids are skipping as I watch them for some reason. So, with either tire, are you spinning at all off the line or are you dead hooking? Assuming you still have the MTs and they are hooking as well as the Hoosiers, I'd go back to them the next time out for sure. You made some other changes, so I'd want to isolate those from the tires and see where that puts you compared to before.
Also, I'm curious about what tires you run on the back for the street. If they're normal street tires I'm sure you're "traction challenged". I mention this because for years I ran Nitto Drag Radials on the street so I could keep from putting on a smoke show under throttle. They really helped but they could still be defeated, especially as they aged.
I recently got a set of ET Street Radials and went to the track shortly after getting them. After putting some heat into them I dead hooked on every run. I was told to start them at about 18 psi and drop down 1-2 psi if needed until I hooked. However, I was told that if they hooked, to run as much pressure as possible since my ETs and traps would improve due to less rolling resistance. I'm really impressed by these tires and I love the fact that they also work great on the street at 32 psi. I realize that your situation is different since you have a clutch but they could be a great overall solution for you. Good luck next time out.
Also, I'm curious about what tires you run on the back for the street. If they're normal street tires I'm sure you're "traction challenged". I mention this because for years I ran Nitto Drag Radials on the street so I could keep from putting on a smoke show under throttle. They really helped but they could still be defeated, especially as they aged.
I recently got a set of ET Street Radials and went to the track shortly after getting them. After putting some heat into them I dead hooked on every run. I was told to start them at about 18 psi and drop down 1-2 psi if needed until I hooked. However, I was told that if they hooked, to run as much pressure as possible since my ETs and traps would improve due to less rolling resistance. I'm really impressed by these tires and I love the fact that they also work great on the street at 32 psi. I realize that your situation is different since you have a clutch but they could be a great overall solution for you. Good luck next time out.
08-21-2012, 02:11 PM
#10
Le Mans Master
08-21-2012, 03:10 PM
#11
Le Mans Master
Member Since: Apr 2001
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Any weather data? Your good passes were last fall...and I'm guessing it's a good bit warmer now? How about humidity, headwinds etc?
Bias Ply slicks will often be slower than radials by a MPH or so....but they obviously worked with the improved 60' even with the greatly increased first gear ratio.
JIM
Bias Ply slicks will often be slower than radials by a MPH or so....but they obviously worked with the improved 60' even with the greatly increased first gear ratio.
JIM
Use you air data in this calculator.
http://www.dragtimes.com/da-density-...calculator.php
Anything in the negatives is good air. Down here in Louisiana he can sometimes hit -1000 to -2000 DA and those are when the best track times come.
08-21-2012, 10:41 PM
#12
Burning Brakes
Thread Starter
I can't tell how well you're hooking because the vids are skipping as I watch them for some reason. So, with either tire, are you spinning at all off the line or are you dead hooking? Assuming you still have the MTs and they are hooking as well as the Hoosiers, I'd go back to them the next time out for sure. You made some other changes, so I'd want to isolate those from the tires and see where that puts you compared to before.
Also, I'm curious about what tires you run on the back for the street. If they're normal street tires I'm sure you're "traction challenged". I mention this because for years I ran Nitto Drag Radials on the street so I could keep from putting on a smoke show under throttle. They really helped but they could still be defeated, especially as they aged.
I recently got a set of ET Street Radials and went to the track shortly after getting them. After putting some heat into them I dead hooked on every run. I was told to start them at about 18 psi and drop down 1-2 psi if needed until I hooked. However, I was told that if they hooked, to run as much pressure as possible since my ETs and traps would improve due to less rolling resistance. I'm really impressed by these tires and I love the fact that they also work great on the street at 32 psi. I realize that your situation is different since you have a clutch but they could be a great overall solution for you. Good luck next time out.
Also, I'm curious about what tires you run on the back for the street. If they're normal street tires I'm sure you're "traction challenged". I mention this because for years I ran Nitto Drag Radials on the street so I could keep from putting on a smoke show under throttle. They really helped but they could still be defeated, especially as they aged.
I recently got a set of ET Street Radials and went to the track shortly after getting them. After putting some heat into them I dead hooked on every run. I was told to start them at about 18 psi and drop down 1-2 psi if needed until I hooked. However, I was told that if they hooked, to run as much pressure as possible since my ETs and traps would improve due to less rolling resistance. I'm really impressed by these tires and I love the fact that they also work great on the street at 32 psi. I realize that your situation is different since you have a clutch but they could be a great overall solution for you. Good luck next time out.
I actually have two sets of 15X8.5" convo pros for the back. Street tires are firestones 255/60/15 and the car will smoke them from a roll pretty easy. The other set of wheels has the Hoosiers mounted.
With The MT drag radials the car felt like it hooked hard and really put me in the seat at launch. They were pretty good on the highway and normal driving. I actually drove 1.5hr to the track, ran the 11.93, and then drove home on them. I wish I still had them but when the trans broke I sold them to a friend for $300. I should of just stayed with them. I ran 22psi in them and only did a short burnout and they hooked great.
The Hoosiers provided a lower 60ft but the car doesn't feel like it launches are hard. I had to run 15psi before they hooked and i had to get them hot to hook.
08-21-2012, 10:42 PM
#13
Burning Brakes
Thread Starter
08-21-2012, 10:44 PM
#14
Burning Brakes
Thread Starter
Use you air data in this calculator.
http://www.dragtimes.com/da-density-...calculator.php
Anything in the negatives is good air. Down here in Louisiana he can sometimes hit -1000 to -2000 DA and those are when the best track times come.
DA on my 11.93 ET run was 1800ft
DA on with slower runs was 1702ft
08-21-2012, 11:05 PM
#15
Burning Brakes
Thread Starter
Could be a combination of factors for the slower runs, weather conditions, state of tune (fresh spark plugs needed maybe), etc. But I experienced the same thing (worse runs) when trying a set of ET bias slicks. The MT ET Drag Radials have less rolling resistance than bias ply tires. They also work better with the C3 suspension; no flexing or ballooning on the top end. I ended up selling the slicks and putting the Drag Radials back on, and the performance was back to normal.
08-21-2012, 11:21 PM
#16
Race Director
I actually have two sets of 15X8.5" convo pros for the back. Street tires are firestones 255/60/15 and the car will smoke them from a roll pretty easy. The other set of wheels has the Hoosiers mounted.
With The MT drag radials the car felt like it hooked hard and really put me in the seat at launch. They were pretty good on the highway and normal driving. I actually drove 1.5hr to the track, ran the 11.93, and then drove home on them. I wish I still had them but when the trans broke I sold them to a friend for $300. I should of just stayed with them. I ran 22psi in them and only did a short burnout and they hooked great.
The Hoosiers provided a lower 60ft but the car doesn't feel like it launches are hard. I had to run 15psi before they hooked and i had to get them hot to hook.
With The MT drag radials the car felt like it hooked hard and really put me in the seat at launch. They were pretty good on the highway and normal driving. I actually drove 1.5hr to the track, ran the 11.93, and then drove home on them. I wish I still had them but when the trans broke I sold them to a friend for $300. I should of just stayed with them. I ran 22psi in them and only did a short burnout and they hooked great.
The Hoosiers provided a lower 60ft but the car doesn't feel like it launches are hard. I had to run 15psi before they hooked and i had to get them hot to hook.
http://www.mickeythompsontires.com/s...m=ETDragRadial
Or were they the Street Radials like this-
http://www.mickeythompsontires.com/s...ETStreetRadial
I'm asking because driving to and from the track on slicks could make for an interesting drive.
The 22 psi for the MTs vs. the 15 psi for the Hoosiers could definitely play a role in the difference in trap speeds.
08-21-2012, 11:33 PM
#17
Burning Brakes
Thread Starter
Yea, those Firestones are definitely overmatched. So, now you have me curious. Were the MTs the Drag Radials like this-
http://www.mickeythompsontires.com/s...m=ETDragRadial
Or were they the Street Radials like this-
http://www.mickeythompsontires.com/s...ETStreetRadial
I'm asking because driving to and from the track on slicks could make for an interesting drive.
The 22 psi for the MTs vs. the 15 psi for the Hoosiers could definitely play a role in the difference in trap speeds.
http://www.mickeythompsontires.com/s...m=ETDragRadial
Or were they the Street Radials like this-
http://www.mickeythompsontires.com/s...ETStreetRadial
I'm asking because driving to and from the track on slicks could make for an interesting drive.
The 22 psi for the MTs vs. the 15 psi for the Hoosiers could definitely play a role in the difference in trap speeds.
I was running the street radials
08-22-2012, 12:49 AM
#18
Burning Brakes
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One of the problems is you made a lot of changes.
When your that close to having it dialed in small changes one at a time is the key to happiness.
If it were me I'd backit up a little and put it back to the way it was and then go from there.
I know it's not practical to completely undo the new mods butget it as close as practical.
R~
When your that close to having it dialed in small changes one at a time is the key to happiness.
If it were me I'd backit up a little and put it back to the way it was and then go from there.
I know it's not practical to completely undo the new mods butget it as close as practical.
R~
08-22-2012, 12:19 PM
#19
Race Director
OK, that makes sense. By the way, your Vette is looking good. 
If I was in your situation, I'd be looking to get another set of the ET Street Radials before the next trip to the track. That should get you back in the ballpark. Then you can start isolating things where you made the other changes to make sure your set up is optimized.
If I was in your situation, I'd be looking to get another set of the ET Street Radials before the next trip to the track. That should get you back in the ballpark. Then you can start isolating things where you made the other changes to make sure your set up is optimized.
08-22-2012, 08:08 PM
#20
Race Director
The wider ratio in the 5 speed might be the issue. Your dropping a little more rpm between shifts and are not in the sweet spot on rpm on upshifts.
