OK. Makes me a bit nervous though, had a close call years ago due to a bad reading gauge and not enough air pressure. Do you think I should try full stiff on the rear shocks at the same time? Any change in launch rpm? It is about 4600, full stall appears to be about 5800. I want to be aggressive on the changes, but don't know how much to change without getting lost.
I really wish I had time to get the converter loosened up before I race again, sounds like that is pretty important as well.

6psi is not low for that tire at all. If you had an issue before, it likely wasn't due to pressure. I would be more concerned at close to 10 psi where you run them. That's overinflated and can be sketchy. I am obviously not implying anything towards you here, because you have been running big tires for years.........But SOME guys get uncomfortable with the big tire "waggle" in high gear. Meaning the car seems to float around in the rear. That's normal and cars just move. The problem arises when guys attempt to correct every little waggle and before you know it, the car is all over the track. Just keep it pointed straight, let the rear sashay a little and she will go right down broadway.

That's a tall tire with a lot of sidewall on a 15" wheel. You get it stood up in high gear and the tread pattern is narrow with a lot of rubber between the rim and the track. It's going to move around. Overinflated, the tire is too tight, the contact patch gets tiny when stood up. It may "feel" more stable, because you have it pumped up tight, but get it in the marbles and it will be out from under you before you know it, because there is no rubber on the track and the tire can't recover.

Hard to say where you should start on the shocks, because I feel certain they are done. I would run the shocks through some sweeps, then tug on the quarters and see if the adjustments actually DO anything. If I was setting this car up from scratch, I would go 6" on the bars from the wheel center, 6psi on the tires, 80% tight on extension and 50% on compression for an initial hit. Not knowing condition of shocks makes this all a crap shoot at best on settings though.

On the front, I would pretty much guarantee the fronts can't control the rise, so I would try them full stiff on extension. You actually WANT it to make too much wheelspeed early and kick the tires.........then you back it off. Since you have data now, you will be able to determine if it just started out TOO hot, or it stuck the tire, bounced and THEN got hot

Realistically though, I doubt you can make that car too hot. It just doesn't have that kind of power. I mean my GTX was a 3200lb ladder bar car with 29.5s. I left on all I could make and it went high 1 teen 60fts. I could go 1.24 on a bowling alley with worn out hides. You are lighter and a much bigger tire. I simply can't see it overpowering that tire

I would take a swing from the start..Full stiff up front, if you can tie ir down to little to no travel even better. I might go 1-2 sweeps from full stiff on the rear at first and then look at the data. I would agree as old as they are they are likely dead. Lower tire pressure as well in the rear. FWIW we run the NA car at 9.4-9.75 and that is a 29.5x10.5 tire, not a W.

As for the launch RPM there area few schools of thought. Some of the fastest cars out there leave as low as the combo will tolerate. Making a "run" at the convertrer. That number seems to vary combo to combo. I am a koolaid sipper in that theory myself with a converter car. We leave very low with the NA 10.5 car. I was a non believer until I did it with mine, ended up leaving at 3900 in a car that made no power below 7700. That led to the best ET's and quickest 60' times for me. The current car we leave at 4200 with a similar power band. Just something else you may or may not want to try.

You have a way to collect and read data now. That will help a ton. My guess is you will end up with new shocks, a lot less tire pressure and eventually a much looser converter...

Some more info for the more experienced
First off, the shocks feel VERY stiff from the "fender" test. On the rear shocks there are 6 1/4 sweeps for extension, I am at five. I couldn't budge the back (maybe 1/2 inch?)at full stiff, so there must be something left.
Afco no longer rebuilds my version of shock and has no parts left
The graph attached was the first pass, and my throttle stop was goofed up and it went almost full throttle before TB release. You can see where it hit the rev limiter instantly ,or almost, and I lifted. I then stabbed it again full throttle and ran it out.
It looks to me as if it tolerated minimum rpm on the second hit? I think I was about ten feet out when I hit it the second time.

When I try and run the car like you guys suggest, I will see how low I can set the rear tire pressure and still not have a wrinkle at rest, as a reference. Sound good? I just spotted Montes' suggestion, 6PSI. Will try that, hopefully no wrinkle at rest.
My next outing will be last weekend of this month, July 29 test day.

I'm not a pro like Monte and Al but I know I
would lower the wheelie bars a lot and the tire
pressure.. the bigger the tire the less pressure
you need for the same weight... also with the wheelie
bars lower you dont let it build the momentum to hit
them hard... I am of the school that I run right up on
the conv.. I dont use any chip.. it goes up on the stall
so it doesnt build the slap the conv can get from low rpm
and I cant say about your shocks.... the only reason you
dont wheelie higher is the bars are on the ground and
wont let it.. which is fine.. but you have that momentum
built up while going up and it will unload the tire...
I can say for fact that my car cant leave from a low RPM
it just blows the tires off.. found that out when the
trans brake took a dump and with the skinny tires I cant
hold it in the lights

MrP, your car likely couldn't leave from low rpm because it didn't have enough grunt. Big tire, low torque. By giving the motor a "run" at the converter, when it hit, the motor welded itself to the converter, tugged it a little, stuck the tire and then knocked it off. Anytime you leave "on the converter" it doesn't shock the chassis as hard, because the flash is essentially gone.

In Greg's case, he can start higher and keep lowering it. His car would leave harder and 60ft better from about a 3200 rpm hit if it will stand the tire up......, but not sure he can get it on the tire that way.

Low wheelie bars more or less "prop" the car up on the bars and not let it crush the tires. Bars are both a crutch and a tuning aid depending on setup. Having them high serves zero purpose other than a safety catch

As I say leave at the lowest RPM the combo will tolerate. All will be different for sure. Lots of variables, torque amount and peak, car weight, SLR, tire etc etc. Just been my observation that generally speaking they will run quicker at a lower launch RPM in many case. Nothing is universal for sure, just a rule of thumb. We run a high RPM SB in the NA car and it leave at a relatively mundane RPM for sure.

Greg, if you don't have a "converter helper", get one, it helps keep the heat in the motor and takes away fuel you don't need or want with the car staged and the throttle matted on the chip. Ron's, Kinsler, FIE (Fuel Injection Enterprises (Spud Miller) all sell them.

I am following this thread with great interest... My Cuda is a lot like Greg's Dart, except i am only running 10.5W-31 slicks.

On a good track, I can stiffen up the front shocks, which are DA Santhuffs and they will lock up solid if you tighten them all the way! I can also restrict the travel to about 2.5".

it hits the tires hard, and i find the air pressure seems to work best about 10.25psi. In that set up it will run 8.48 at 158 mph with a 1.18 60 foot.

my challenge is that when the track is not good, I seem to need to loosen the front shocks, add travel, soften the ext on the rear and lower the air pressure to 9.75 to get it to work, and it still wants to spin.

I need to learn the 'balance act" between all these variables to adjust to conditions better, so Monte and Al, please keep the advice flowing! If you help Greg, you will help a lot of us.

Thanks,

Arnie

Arnie do you have a data logger at all? If not might add that to the Christmas list, invaluable tool.

No way lower air pressure helps on a BAD track. You let the tires down when track is GOOD and tighten them up when bad. Has NOTHING to do with sidewall. Its about the contact patch

I am OK with others getting help with 60 ft settings. It will help us all

All of this is based on torque... if you guys
have a ton of torque you will be different than
the guy with less torque... but from what Monte
and Al are talking about is higher torque engines
but based on what they are saying you can get a idea
of what direction to go.. all cars are different and
will take a different set up... I know why I did what
I did.. it was lack of torque.. but it worked for me..
it gave me a 1.19 60'

Al, i don't have a data logger, but I am running a MSD grid, so I guess the next step is a data logger...

Monte, I am launching off the Transbrake at 3,400rpm and it has always hoooked better this way compared to 4,000+ RPM. Alky terminator and 3 speed 727, so should i try 3,000 or 3,200 ??

Interesting comment on the air pressure. With the 10.5W-31 on a 12" rim and the car weighing 2,850#'s w/ driver, what air pressure range should I try for good track or bad track??

I am going Racing on Sunday and plan to tighten the front extension, but would like to know "what order" to try things. Is it front shocks first to find enough transfer but as slow as possible, then rear extension, then rear compression, then fine tune air pressure???

Greg, I should come down to Brainnerd this fall and run with you!!!

We have VERY LITTLE torque in the NA 10.5 car. It is a Small Block 10,000+ rpm engine. It works just fine the way we are discussing here.

IMO with the front tighten it and limit it as much as you can. The rear extension needs to be tight on a ladder bar car, will it go tight enough with your shock valving, who knows right now. Video is all you have to work with so start there. Camera focused on a 3/4 side view mainly looking at rear tire to see what is going on. Compression is used to keep the tire planted once you find the sweet spot. IMO air pressure is probably the first place to start out back. But would not be afraid to make more than one change at a time. Would not necessarily do them all at once but would try to get the front end slowed down, lower the pressure in the tires and tighten the extension a tad all at once. Then watch the video and make changes accordingly based on what you see on video.

FWIW We run our TT5 at 9-9.7 depending on track conditions. We video EVERY run the car makes. Also look at the data on every pass. Once you get close the adjustemts will be smaller but you got to get the car up on the tire first.

Greg, I should come down to Brainnerd this fall and run with you!!!

[/quote]
Come on down! It would be great to meet in person. Let me know and I can save a pit spot.

Greg, Thanks for the offer on the pit spot! Hopefully in September.

Al, do you run 9.4 when the track is good, and raise it to 9.7 if the track is bad like Monte is suggesting? i always thought to go lower when the track was not prepped as well, but having said that, it usually didn't help much...

I can lower to 10 psi and if it hooks, lower it to 9.75, etc, to test this theory...

This is not saying anything bad about anyone in particular......but MOST racers don't understand tire pressure.

Brief rundown, although I have done it before in other threads. Lower pressure lets the tire "cup" in the middle at launch. Basically just using the edges of the tire. This is beneficial almost all of the time, because 99% of cars are overtired for the power they have and it makes it tough to get the car "on the tire" early. The more air you put in the tire, it flattens the tire out early and actually puts MORE rubber on the ground early, where VERY few cars actually need it.

Lets look at this from a realistic standpoint. Many bracket guys and or heads up guys run a tire nearly as big on their low horsepowered door cars and pipe racks, as you see on fuel funny cars and dragsters. Think about that a minute..............So if that is the case, do you really think your 800 N/A hp bracket car with 15x33s is "blowing the tire off" at the hit?............hardly. As with MOST cars, it crushes the tire at the hit as it is trying to drive the rims into the pavement. After flattening the tire, it and the suspension rebound, hopping the rear of the car and spinning the tire. This happens SO fast, guys think they blew the tires off at the hit. This NEVER happens

No offense taken Monte, I am always willing to learn...

So in my case with a 34" ladder bar car, weighing 2,850#'s with driver and making 965hp while launching with a 3 speed 727 auto, and 4.56 gears on a 10.5W - 31 on a 12" rim, where would you start the air pressure??

I still have room to tighten the extension on my DA Strange rear shocks (110# springs) to slow down the crushing of the tire.