What air pressure works best in your ET Drag stiff wall slicks
06-17-2011, 09:05 PM
#1
What air pressure works best in your ET Drag stiff wall slicks I am going to start off at 14 psi tomorrow and then keep leting out another pound until she hooks, or I get to 10 psi. Does that sound like a good plan?
What psi works best for you guys?
If I think 13 is the best than I need to keep checking them and airing them down to 13 again befor each run, correct?
What psi works best for you guys?
If I think 13 is the best than I need to keep checking them and airing them down to 13 again befor each run, correct?
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06-18-2011, 07:42 AM
#6
12 before the burnout, and that worked for me with a 3350 lb car. If the car is really light, you may be able to get away with a little less, if the car's alot heavier, it may require a little more.
I wouldn't bother starting at 17 psi. If you can hook with the tires at 17 psi you probably don't need to be running a 28 inch tire, and could most likly get away with a smaller size, and have the same results, maybe better (lighter tire)
OP, I don't know what you're spraying but a 370 with a fogger, and say a 30 jet is going to make enough power for mid to low 9 second passes. 12 psi... I would go in 1/2 lb increments on the adjustments from there unless you totally blow them off at the hit then maybe a full lb, but I would be looking at shock settings and the like before dropping the tire pressure any lower then 11. I doubt that you will find any more then 13.5 to really work.
I wouldn't bother starting at 17 psi. If you can hook with the tires at 17 psi you probably don't need to be running a 28 inch tire, and could most likly get away with a smaller size, and have the same results, maybe better (lighter tire)
OP, I don't know what you're spraying but a 370 with a fogger, and say a 30 jet is going to make enough power for mid to low 9 second passes. 12 psi... I would go in 1/2 lb increments on the adjustments from there unless you totally blow them off at the hit then maybe a full lb, but I would be looking at shock settings and the like before dropping the tire pressure any lower then 11. I doubt that you will find any more then 13.5 to really work.
06-18-2011, 08:03 AM
#7
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12 before the burnout, and that worked for me with a 3350 lb car. If the car is really light, you may be able to get away with a little less, if the car's alot heavier, it may require a little more.
I wouldn't bother starting at 17 psi. If you can hook with the tires at 17 psi you probably don't need to be running a 28 inch tire, and could most likly get away with a smaller size, and have the same results, maybe better (lighter tire)
OP, I don't know what you're spraying but a 370 with a fogger, and say a 30 jet is going to make enough power for mid to low 9 second passes. 12 psi... I would go in 1/2 lb increments on the adjustments from there unless you totally blow them off at the hit then maybe a full lb, but I would be looking at shock settings and the like before dropping the tire pressure any lower then 11. I doubt that you will find any more then 13.5 to really work.
I wouldn't bother starting at 17 psi. If you can hook with the tires at 17 psi you probably don't need to be running a 28 inch tire, and could most likly get away with a smaller size, and have the same results, maybe better (lighter tire)
OP, I don't know what you're spraying but a 370 with a fogger, and say a 30 jet is going to make enough power for mid to low 9 second passes. 12 psi... I would go in 1/2 lb increments on the adjustments from there unless you totally blow them off at the hit then maybe a full lb, but I would be looking at shock settings and the like before dropping the tire pressure any lower then 11. I doubt that you will find any more then 13.5 to really work.
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06-18-2011, 01:07 PM
#8
12 before the burnout, and that worked for me with a 3350 lb car. If the car is really light, you may be able to get away with a little less, if the car's alot heavier, it may require a little more.
I wouldn't bother starting at 17 psi. If you can hook with the tires at 17 psi you probably don't need to be running a 28 inch tire, and could most likly get away with a smaller size, and have the same results, maybe better (lighter tire)
OP, I don't know what you're spraying but a 370 with a fogger, and say a 30 jet is going to make enough power for mid to low 9 second passes. 12 psi... I would go in 1/2 lb increments on the adjustments from there unless you totally blow them off at the hit then maybe a full lb, but I would be looking at shock settings and the like before dropping the tire pressure any lower then 11. I doubt that you will find any more then 13.5 to really work.
I wouldn't bother starting at 17 psi. If you can hook with the tires at 17 psi you probably don't need to be running a 28 inch tire, and could most likly get away with a smaller size, and have the same results, maybe better (lighter tire)
OP, I don't know what you're spraying but a 370 with a fogger, and say a 30 jet is going to make enough power for mid to low 9 second passes. 12 psi... I would go in 1/2 lb increments on the adjustments from there unless you totally blow them off at the hit then maybe a full lb, but I would be looking at shock settings and the like before dropping the tire pressure any lower then 11. I doubt that you will find any more then 13.5 to really work.
But if that works well, do I want to keep letting air out as the tires get hotter and build pressure each pass? I would assume so but just thought I would ask.
I have a 28 fuel and a 105 nitrous jet. I am thinking I will be happy to be in the mid 10's. 9's would be crazy though. I am the only guy with a fuel injected motor at the local track so I am having a blast just beating the guys that have trailer only sbc's They all sure have allot of questions after they see me run
THey look so shocked when I tell them I daily drive this with AC and cruise. LOL 
06-18-2011, 01:25 PM
#10
Tire pressure will move around depending on how consistent your burnout is, track temp, ambient temp. You adjust your burnout for those conditions to try and maintain a consistent tire surface. I don't see many guys measuring post burnout tire pressure, but I do see IR thermometers at the track 
06-18-2011, 05:46 PM
#11
Ok I am going to start at 13 psi. Since this pig has to weigh at least 3600# and I am 250. I need to stop by the dump and get this thing on the scale. (I may have to wait another week if the rain starts up again)
But if that works well, do I want to keep letting air out as the tires get hotter and build pressure each pass? I would assume so but just thought I would ask.
I have a 28 fuel and a 105 nitrous jet. I am thinking I will be happy to be in the mid 10's. 9's would be crazy though. I am the only guy with a fuel injected motor at the local track so I am having a blast just beating the guys that have trailer only sbc's They all sure have allot of questions after they see me run THey look so shocked when I tell them I daily drive this with AC and cruise. LOL
But if that works well, do I want to keep letting air out as the tires get hotter and build pressure each pass? I would assume so but just thought I would ask.
I have a 28 fuel and a 105 nitrous jet. I am thinking I will be happy to be in the mid 10's. 9's would be crazy though. I am the only guy with a fuel injected motor at the local track so I am having a blast just beating the guys that have trailer only sbc's They all sure have allot of questions after they see me run
THey look so shocked when I tell them I daily drive this with AC and cruise. LOLTires.. I'd set them at 13 if the car's heavy before the burnout, do a good 5 count burnout in 2nd gear, and then off the line lock and power thru until they grab. Then, stage and go.
I'd reset them back to 13, every pass. Which means you'll be taking air out all day, but that's fine... it's normal. Try to stay as consistant as you can with the burnout times, and where you stage the car (in the groove, etc... a buddy to line you up helps alot with that).
If it blows the tires off I'd drop the pressure to 12, and if it still spins it's shock adjustment time, etc.
06-21-2011, 07:03 PM
#14
If you have a zex kit on there I don't want to know anything about it. The only thing that zex makes that's worth anything is their plate kit. Every other thing I've seen from them looks like trouble to me... no way an I trusting a fuel and nitrous solenoid that fit in a purple box that's not much bigger then a full size nitrous solenoid from any of the other companies.
Even for a high fuel pressure system that's screwy jetting... I'd be very careful with that.
Even for a high fuel pressure system that's screwy jetting... I'd be very careful with that.
06-22-2011, 09:07 AM
#15
I guess going by JL's statement I don't need 28" slicks. 
I run 18lbs in my 28x10.5x15s tires and it always hooks unless the track is crap and everyone else is spinning too. I never bothered lowering the pressure because it works where it's at.
I am not saying that 18lbs is the best air pressure, only sharing what has worked for me. My car is also NA so I'm sure that makes a big difference.
I run 18lbs in my 28x10.5x15s tires and it always hooks unless the track is crap and everyone else is spinning too. I never bothered lowering the pressure because it works where it's at. I am not saying that 18lbs is the best air pressure, only sharing what has worked for me. My car is also NA so I'm sure that makes a big difference.
06-22-2011, 03:47 PM
#16
You probably don't need them.
From experience, here's the air pressure that I've found to work, +/- a lb by tire size:
26x8.5 15.5
26x10 15
27.11.5 qtp 14
28x9 14.5
28x10.5 13.5
28x10.5s 13
29.5x10.5w 12
30x10.5 12
That's as big as I have dealt with personally... I don't think the car with the 29.5 and 30 (same car) needed that big of a tire.. but that's what was on it, when the car was bought... so that's what stayed on it.
Jimmy how fast is the car, and is it a stick car or an auto car? If it's a stick car, and you're running it n/a you may need the air pressure to get the tires to spin a revolution or 2 to stop it from bogging. 26 inch tire would probably accomplish the same thing.
From experience, here's the air pressure that I've found to work, +/- a lb by tire size:
26x8.5 15.5
26x10 15
27.11.5 qtp 14
28x9 14.5
28x10.5 13.5
28x10.5s 13
29.5x10.5w 12
30x10.5 12
That's as big as I have dealt with personally... I don't think the car with the 29.5 and 30 (same car) needed that big of a tire.. but that's what was on it, when the car was bought... so that's what stayed on it.
Jimmy how fast is the car, and is it a stick car or an auto car? If it's a stick car, and you're running it n/a you may need the air pressure to get the tires to spin a revolution or 2 to stop it from bogging. 26 inch tire would probably accomplish the same thing.
06-22-2011, 04:01 PM
#17
It's an auto car(TH350 w/ 5500 stall) and it will run 10.50's in decent weather. I went with the 28" with the intention of swapping the 4.11's for a lower ratio. I am still trying to get the weight down as much as possible and want to see where it crosses before I make the swap.
06-22-2011, 04:09 PM
#18
Hard to say. If you are leaving off the footbrake I don't doubt that you can get away with that tire pressure.. if you try leaving off a transbrake it's probably going to spin.
The speeds you're running a 26 will work if you work the car some, 28's make it easy to be consistant.
If you know anyone with a set of 26's mounted up that would fit on your car I'd try it and see if it goes any faster, on the same night. Just swap the tires and see what happens. That will tell ya if the gearing change will help as you suspect, and tell you if the gear change will still get you thru the traps rpm wise...
I wouldn't be surprised to hear that it works the same with the 26's, maybe better if the gearing is too tall as it sits... if the gearing is way off for what the car wants it may pick up a bunch. Could get worse too depending on the powerband. One of those thing you have to try. If you have a good prepped track, traction, likly won't suffer at all.
There's a class that the max tire is a 26x8.5 that's run at a bunch of places across the country and there's guys going in the 5.7 range to the 1/8th mile on them. Probably scary to watch I'm sure... but they are doing it... if they can get down the track at that power level on that tire you probably will with no issues...
The speeds you're running a 26 will work if you work the car some, 28's make it easy to be consistant.
If you know anyone with a set of 26's mounted up that would fit on your car I'd try it and see if it goes any faster, on the same night. Just swap the tires and see what happens. That will tell ya if the gearing change will help as you suspect, and tell you if the gear change will still get you thru the traps rpm wise...
I wouldn't be surprised to hear that it works the same with the 26's, maybe better if the gearing is too tall as it sits... if the gearing is way off for what the car wants it may pick up a bunch. Could get worse too depending on the powerband. One of those thing you have to try. If you have a good prepped track, traction, likly won't suffer at all.
There's a class that the max tire is a 26x8.5 that's run at a bunch of places across the country and there's guys going in the 5.7 range to the 1/8th mile on them. Probably scary to watch I'm sure... but they are doing it... if they can get down the track at that power level on that tire you probably will with no issues...
