Trying to help a friend of mine out. We are just absolutely clueless. 245 American with a procharged 538. It will blow the tires off the line more times than it will hook up. Off the trailer it goes right down Broadway but after that it's a crap shoot. He's pulled /added timing, new penske shock, played with lauch rpm, put on new big bubbas, tried different tire pressures, 4 link adjustments and who knows what else. Anyone have any other ideas? Car worked great when it was n/a

Rusty, JR Baxter and Greg Kelly here are who you want to be talking to. Besides them, Danny Nelson, Anthony Bettozzi snd Steve Furr to name a few that know what they are doing.

As a WAG, converter not right for the combo.. or junk track.

How fast did it run when it went down?

Launch rpm?

By chance could the shock be topping out due to hitting harder? Where is the timing and launch rpm? How much boost at the hit? Same converter as na or new tighter?

Launched anywhere from 3600 to 4800. He had borrowed a bolt together to try but I cant remember the size or stall. He has a new 9 inch in there now made for the combo. This has happened at a few different tracks

quote:

Originally posted by Bucky:
By chance could the shock be topping out due to hitting harder? Where is the timing and launch rpm? How much boost at the hit? Same converter as na or new tighter?

He got a new shock from penske a few weeks ago and that was no help. I know he talked to Travis at American and he can't figure out either why it's doing this.

Set base timing to 30 degrees, drop launch to 3000 rpm, pull 15 degrees at transbrake release put timing back in at 1.0 second. Once you figure out how to make it run from there, you can start fine tuning the timing retard (amount and duration). The faster you get all the timing back in it the faster it will go.

You didn't post how many degrees you are pulling at transbrake release, nor did you post total base timing, but too much timing will make it violent down low.

If it still wont leave drop the base timing even lower (25 ish) to see if you can get it to leave consistently or retard the timing even more at transbrake release (maybe 20 degrees).

If it still won't behave drop some boost out of it. When it does go down the track how fast is it?

What is the converter flashing to?

quote:

Originally posted by Triple Nickel:
Set base timing to 30 degrees, drop launch to 3000 rpm, pull 15 degrees at transbrake release put timing back in at 1.0 second. Once you figure out how to make it run from there, you can start fine tuning the timing retard (amount and duration). The faster you get all the timing back in it the faster it will go.

You didn't post how many degrees you are pulling at transbrake release, nor did you post total base timing, but too much timing will make it violent down low.

If it still wont leave drop the base timing even lower (25 ish) to see if you can get it to leave consistently or retard the timing even more at transbrake release (maybe 20 degrees).

If it still won't behave drop some boost out of it. When it does go down the track how fast is it?

What overdrive and how much boost? Most of the PC guys I know have 25 or less base timing and pull up to 10* and all back in before 2 secs. Should also have a 10 inch converter IMO. And put Hoosier c1550s on it

2019 American 245” with a F1R 540. I had the exact same struggles earlier this year. Two biggest changes that turned the car around was to ditch the Penske shock and got a custom built JRI from Competitive Suspension and went with a much tighter converter from Abruzzi. I had a 10” Q3 and it would flash over 7000. Went to a Q6 and it killed 500 ish in stall. I also lowered tire pressure from 5.6 to 5.2. 3195MT tire. I run my base timing at 26* pull 8* at the hit and have all of it back in 1.8 seconds later or basically as soon as the car is in high gear. Runs low 4.20’s 168 with this setup. Hope that helps

I would get more back to the very basics...

what is gear in trans

what is rear gear

what blower is on it and if its gear drive...what ratio...and if its belt,what pully

and last what is the spread of your top and bottom bars

Trying to get as much info as I can for you all. It's an F1R, running 4.10 gears and I believe 1.80 first in trans. I believe he's running a whole lot more timing than anyone has suggested here like in the high 30 degree range. Ill get some more info in the morning. I appreciate all the info so far. Keep it coming

quote:

Trying to get as much info as I can for you all. It's an F1R, running 4.10 gears and I believe 1.80 first in trans. I believe he's running a whole lot more timing than anyone has suggested here

my opinion ... way too much rear gear and trans first gear...add wack timing numbers and who knows what drive ratio or pulley on there...she sounds vicious!!

quote:

Originally posted by jenavet:

quote:

Trying to get as much info as I can for you all. It's an F1R, running 4.10 gears and I believe 1.80 first in trans. I believe he's running a whole lot more timing than anyone has suggested here

my opinion ... way too much rear gear and trans first gear...add wack timing numbers and who knows what drive ratio or pulley on there...she sounds vicious!!

Na, perfect combo

quote:

Na, perfect combo

well you are a wild man!!

As mentioned, launching @ 15-17* and then ramping it back to your full timing number is the key thing with getting them to stay hooked.

If he has a Racepak data log I'd be glad to look at it and offer suggestions.

Key message here is kill timing till it settles down, set the base low then pull enough to get a handle on it. Then creep back up on the power via base timing and decreasing the amount of retard. No clue on the OD of the blower but then again does it really matter, you gotta kill it a bunch (one way or another) to make it go down the track consistently. One way to do that is through base timing and timing retards. My initial guess at 30 was based on the idea that the OD in the blower isn't set on kill (4 teen power range in a dragster = on kill to me for bracket racing), if it is then base timing needs to be closer to the 26, then pull 15 at the hit, and ramp back in. If you wanna hold it out till 2 seconds that's fine too. Key idea here is to get rid of some of the timing how you do it is up to the tuner. I threw some numbers out there as a reference.

That first gear is likely too steep and i'd consider dropping some rear gear too, but it should go down on a 4.11, just might be a little aggressive. If money was no object, drop in a 1.58 sonnax first gear and drop rear gear to 3.70 then try that. Timing is much cheaper tho in the short run as long as you don't hurt the motor....

PS i'm no procharger guy, roots stuff is all i have to work from, so gross numbers may be off but the idea is the same PC vs. roots.

Just for reference I run a 180/370 gear in my blown TD, works really well for me. The 370 keeps the converter a bit on the loose side but it runs good speed without allot of RPM

Something stupid, but I assume the air in the shock was checked? I've seen no air in shock do this.
Sounds like a lot of gear and timing though if it is upper 30s.