Got some issues going on with B/O mainly but would like to have some conversation with active hardtail dragster guys.

What do you want to know

Mine is a hard tail. Double slip joint...

Some background. Racetech, owned it since new - haven't really raced it all that much over the years - had to let it sit quite a bit due to job changes, etc.

Had a 509 but messed up the crank, I turned it into a fresh 555 a few years ago, but haven't had much luck getting comfortable with it. Ran it a couple of races in 2019, just did nothing but fight with it - some of my own screw-ups and some of it trying to figure out the additional power.

I think a lot of it is the b/o - I never feel like I get a decent one like I did with the 509. I've jacked around with different rpm levels for that along with launch and shift. I run Hoosier C07 - same tire I have always used on it, new set last year but ended up not running due to the virus stuff. Finally went to VMP with it yesterday, got one 1/2 decent hit on it and that was it. Just wondering what you all are using for RPM#s, tire pressure and anything else you want to throw at me. Much appreciated.

I’ve run CO7s for awhile I have burn out limiter set at 45 to 4800 have done low to high gear and just high gear are you not getting any wheel speed

Not positive about that but the only difference between the car with the 509 and 555 is the cubic inches. I reused everything, convertor, camshaft, carb, intake, etc, etc.

My burn out limiter is on a button and I do let go and let Main limiter take over if it doesn’t feel like I’m getting enough wheel speed

The one year at the divisionals. The Goodyear truck never showed up. The (H) truck was there.
Went to a CO7. Fought for close to a year with shake. Didn't matter what pressure. Broke more *** than i could fix. Went back to GY. Stiff sidewall.
Smooth as glass..Just curious, since it is a HT,
Do you have laterals on the rear plate?. During the run, you feel the car is slightly moving around on you?. Look closely at the edge of the tire. (Both Edges) How much scuff?


Mine BO limiter 8000
Hit 4800
Shift 7600
Fall back 6900
Trap 7400
High gear BO only.

This message has been edited. Last edited by: TD3550,

Although not "active with Hardtail", when we ran ours a few years ago;
* the burnouts were always done in high gear with a 6000 chip
*launch chip was 4200 - 4400 depending on conditions
*shift chip was 6800 falling back to around 6100-6200
*finishline rpm was normally 7050 - 7150

This set up was used on both our 509 and our 548 with great repeatability.

NOT with Hoosier tire though. (not much luck with consistent performance in temp swings)

We had much greater success with the MT 3084s
on 15" wheel at 5.9 lbs all season regardless of 40* temps in April/May or 90*+ temps in the heat of summer right on through to the cold fall temps of Oct/Nov...

been running T/D with the Spitzer dbl slip hardtail with success for 8 years ... first thing I'll suggest is get rid of that tire .... the biggest nightmare we ever fought was trying to do a burnout with that tire without losing all the fillings out of his teeth ..

This message has been edited. Last edited by: Paul S/Q,

You too Paul. Mine shook so bad it took out the bronze thrust in the planets. Split right in half.
In the beginning i thought a death shake from the planets. All during the CO7 adventure.

we've run all the different m/t compound tires and ALL of them are great in the burnout ... ...burnouts for us in high gear only, @ 6300 ... we've been as fast as 6.05 with the car , once you get that burnout fixed , we can go from there

I have a racetech hardtail. My burnout chip is 6800. I've run a few different MT with no massive shake. Hoosiers only last on the car 12 runs they broke so much stuff.

Not sure what other peoples burnout procedure is like but I find my burnouts are much smoother if I'm on the brakes as soon as I start getting off the gas. Gets the wheels speed down before they grab.

Yes _ I do have laterals on the rear plate. With the smaller engine, the car hardly moved. I haven't had a decent run on this engine yet to really have a comparison. Without measuring about 2"+ on each side of tire.

I going to go back on rpm chip - had it up to 7500 and looking through my notes from a few years ago, the car liked 6600 better. Right now, before I feel like I have a decent b/o, the tires are grabbing.

I'm seeing that a lot of you are posting numbers closer to what I used to use and that has me thinking that I am off in left field (so to speak).

I do the burnout in high only, have a button (chip) but have tried to manage it with the pedal with no luck.

Looking at the specs on the MT 3084 - it says tubes are required? Is that real?

What about waterbox - minor, heavy?
Roll into the b/o or just stab it hard?

This message has been edited. Last edited by: chasracer,

I am going to give the Hoosier 1550 a try this spring. Coming from a 17" wide D06. Moving to a 16x16. Spitzer chassis

Before I left for florida, I had MT 3186's on mine. 5.5lbs, 5500 launch....never an issue. Went to florida, switched to alky, and a new set of 3195's. Been up and down in pressure, up and down in rpm. Only time it didn't shake on me is at 5 psi and 5k launch. But was told I was killing sidewalls...so I think mine is a wheelie bar issue (should be running mine, Top38 has been helping me with it) and a launch rpm issue. Never had a set of Hoosiers on the car, so no experience with them, but maybe a video of the car leaving the line will help. Watch what it does and go from there.

The secret with a ht is to cheat yourself on the b/o....DON'T get your money's worth.
High gear, mat it on a 6000rpm limiter and LIFT before it hooks...Get the tires out of the water box obviously but not much further out...
This is what works for me when I want to get a couple of laps on my old comp B/ED....

Never ran a tube in the 3084S MT.

Used them for several years with great results on our hardtail. A well watered water-box for best results. First burnout of the day was fairly aggressive. The remainder of the day moderate burnouts per MT engineering tech suggestion. We normally roll through just past the edge of the water then stab it. Lift just as it starts to hook. This worked for us...

quote:

Originally posted by chasracer:
Yes _ I do have laterals on the rear plate. With the smaller engine, the car hardly moved. I haven't had a decent run on this engine yet to really have a comparison. Without measuring about 2"+ on each side of tire.

I going to go back on rpm chip - had it up to 7500 and looking through my notes from a few years ago, the car liked 6600 better. Right now, before I feel like I have a decent b/o, the tires are grabbing.

I'm seeing that a lot of you are posting numbers closer to what I used to use and that has me thinking that I am off in left field (so to speak).

I do the burnout in high only, have a button (chip) but have tried to manage it with the pedal with no luck.

Looking at the specs on the MT 3084 - it says tubes are required? Is that real?

What about waterbox - minor, heavy?
Roll into the b/o or just stab it hard?

Not a fan of the CO7 tire for your deal, CO6 would be better and even better would be the MT. BO rpm around 6800 -7000. Launch 4600 to 5200, lot will depend on the converter and rear gear.
Usually Hardtails like to be hit hard.

On the BO's, make sure your off the throttle before the track prep starts, especially with the Hoosiers.

[QUOTE]Originally posted by Mad Dog:

. We normally roll through just past the edge of the water then stab it. Lift just as it starts to hook. .[/QUOTE

BINGO ...