How to soften the hit?

I am considering changing over to a 1500 Hp, 540 BBC with a 14-71 for my dragster. One thing that has me concerned is how to soften the hit on the tires. I use a MSD digital box now and I can take some timing out when I need to. Would this be best for a blown application or is there a better way?

I am seeing guys who are having tire shake getting off the line and I want to know how you solve the problem when you encounter it.

John

 

Post up some more info. What wheel base is the car? Does the car have any suspension? What tires? What rear end ratio? What trans? What clutch or converter? What class or what is your goal with this car and engine? Whatever your answers are to these questions, chance are somebody here has been through the same thing and can help you.
Brian

 

Current combination

235” wheelbase S&W, 4 link, Goodyear 33.5" x 17.0" - 16" 2532 D-2A, 4:11, PG trans 8” converter. Current engine is 522 BBC with hat injection, approximately 950 hp, runs 5.0-5.05 with my 275 lbs. T/D and bracket, Goal is 4.20-4.25 in the 1/8.

 

Bare Naked Ladies????

Back to the original question. How do you control the hit with a supercharged Top Dragster. Air pressure in the tires? Change the blower ratio?

I have never had a problem with tire chatter, tire shake, whatever you want to call it. Is it all related to tire speed?

To be sure someone on this forum can answer this question?

 

I have a Procharged TD. Best run 6.52 210 (4.20 1/8). Run it in fast brackets too at 6.80's. I use ignition timing and a tight converter and pulleys to get what I want.

Similar combo to yours S&W 230" 4-link, Hoosier 34.5 tire.

here are some specs: http://www.motorsportsinnovations.com/Race-Team/procharger1.htm

Greg

 

I would say all of the above. You can try to control the engine by the blower ratio, by the timing, by the convertor, by the tire. You may also find that the car will handle what you can throw at it. I ran a 125" altered with a 440" BBC with an 8-71, powerglide, same rear gear and tire, and no suspension, and I never had a problem with it spinning. It was around 1150 hp at altitude.
Put the new engine in and if the engine is running good and happy, don't change the blower or timing, but play with the convertor, or the suspension. Try a different tire. There things that can be done to keep it from spinning, but you wont know if you need to worry about it until you try the new combo out.
Brian

 

Greg:
Your combo is very similar to what I had in mind. I talked with them at S&W about the shorter arms for the anti-roll bar yesterday. Making the brackets is no problem since I built the whole car in my shop from a kit. I had also looked at the wheelie bar from S&W.

It looks like you were getting some ring gear deflection from the pictures you had on your website, is that correct?

Steve Morris told me I could use the steel rods, "Steel rods at a 2000 HP level will go 300 passes +".

How much fuel does your engine use on each pass? My fuel tank holds a little over 5 gallons of fuel. I am assuming that you are using alcohol?

One thing I wanted to do was retain the radiator so I could drive back to the pits. I am all the pit crew I have.

What size headers do you run?

Thanks for the reply.

John

 

John, if you drive it around the pits you will need a larger tank, I have an 8 gal tank, to drive it to the line and pull up between passes it will take a ton of fuel. My car use's between 4 and 5 gal per 1/8 mile pass including the burnout....and that is with me pulling it around the pits and to the starting line and back to the trailer. You need to pull it back to the trailer so you can get an accurate read of the plugs. Also...a pro-charger does' not beat a crankshaft like a roots blower will. The old adage is would you rather beat your expensive crank with a steel hammer or an alum. hammer.

 

I like that Jody. "The old adage is would you rather beat your expensive crank with a steel hammer or an alum. hammer." Tim and I talked over many of the issues I have with this change over. I will see you Saturday and we can go over all these questions. I appreciate you taking the time to introduce me to "blown alcohol" racing.

John

 

It looks like you were getting some ring gear deflection from the pictures you had on your website, is that correct? No, just had to clearance the Strange cast housing to fit the beefy Moser caps.

Steve Morris told me I could use the steel rods, "Steel rods at a 2000 HP level will go 300 passes +". I'm Oliver steel pushing 500 runs - new 625 material bolts this past winter.

How much fuel does your engine use on each pass? My fuel tank holds a little over 5 gallons of fuel. I am assuming that you are using alcohol? Yes, alky. I use about 2.5 gallons including driving to the lanes and back to the trailer. I'm EFI so the part throttle and idle is like it's NA.


What size headers do you run? 2 1/4 to 2 3/8 step - yea i know not a blower header but it's what I had.

Greg WWW. MotorSportsInnovations.com

 

my combo

I have a 540 1471 HH retro big chief motor 25%OD. Been through the tire shake problem a lot this year. I have 245" swing arm. I run 3.90 gears, 34.5 tires, TCI 10" converter stall at 6700, shift at 7600. Alum BME rods. I best I've run is 4.12/170 6.43/211. I think you are going to need a 9.5 or 10 converter and taller tires, difinently a ringless input shaft - trust me you are going to be making a lot more torque than you ever dreamed. When I went from 871 to 1471 broke three vasco ring style shafts in three launches, then a 1" ring style in 2 passes. This is the reason for the taller gear, taller tire, etc.

I use timing to get wheel speed and 60' times where I want them. There are are lot of varying options about what is a good speed at different times off the starting line.

I have been running a particular brand for several years with a little tire shake every now and then in years past. I got a lot more frequent this season, no matter what wheel speed I tried.

Recently I had my Ohlins shock made to be as stiff as they could get it at the first movement of the shock and I changed tire brands. Didn't have option of changing one at a time and racing over now.

One or both of these made it work very well, with about 18 passes in varying conditions with no down low shake (rattles when shift, working on that next).

Maybe this will help you get started.