Drag Racing Discussions > Front Engine Dragsters
Rear Tire selection
masracingtd1167:
Jon Thank's for the reply's ! Very interesting stuff !
wideopen231:
Thanks Jon. My bad on the gear it is 1.69 not 1.68. Have not weighed car yet and hoping for less total weight than stated,never upsetr when they weigh less. Hoping for high 1400's,but with battery and cpl extra electronics trying to keep expectations realistic. Aluminum carrier ,aluminum pump in trans , minimze everything,plus drilling holes in holes to get air out should help. Right now 4 gallon tank and battery on nose,215# driver hanging out back. Have fire bottle and NOS bottle(mostly topend and some midtrack) to mount that can be used for ballast also.
The 50" out was changed during build after long talk with that Parks guy.The 4.11 is in because it was here. I have 4.30 and 4.56 I can get to try at any time. $.11 is leaving sme on table for 1/8 but not so much 1/4 mile.Not many 1/4 mile tracks we might run but a few and with bracket deal I need can do both combo.
On the expected HP number. Don't laugh to hard. I used desktop dyno program. Was skeptical at first. After running number real worl combos thru it and getting aroun 1 to 3% differance in real dyno number I have come to respect it more. If you give it real numbers for headf flow,induction system,real compression and accurate cam specs it will impress you with its accuracy. I am amzed anyone can write a program that can run as many compariosns and get in ball park much less as close as it does.Main thing I have found is cam and HEAD FLOWS,imagine that.
If interested and have real dyno and numbers needed I can run them thru program and see how close it comes.Kind of hobby checking and working with it while wife watchs tv at night. Alann Starr once told me "If you go a day w/o learning something new you wasted a day of you life." Pretty sure learning anything on engine would qualify with the old man.
Sorry but glad to see Im not only finding it hard to find info on simular setup. Heck if it was easy it would bore the heck out of me. Done a lot and not much of has been picked because it was easy.
Thanks for input and info you found out from contacts.
To Op sorry not trying to highjack thread,figure info in public room better than PMs where only one learns.
Chris McBride
JakeB23:
This is good information.
What about air pressure? What is everyone running for air pressure?
JrFuel Hayden:
Jake, good question. well lets see "what is everyone running for tire pressure" ;
Scott Parks ran 4 1/2 lb in his 33x12x15 on 12" bead lock wheels in their NHRA record [ 6.76, 197 mph] holding A/ND with their 385 ci SBC with monster flowing heads. Scott and Frank's car has the motor out 52" to help keep the tire speed up since the big head motor makes less torque than any other A/ND racing. Again less tire pressure gives you more tire speed.
i just talked to a racer just having fun in his low budget FED running in the 8's using 10.5 slicks running 7 1/2 lbs of pressure.
A friend racing Heritage A/FD with a blown alky late hemi runs 32x14.5x15 GY runs 6 1/2 lbs and 6.40's
We run 5 3/4 to 6 1/4 lb depending on track conditions on 12" rims with D2585 GY 31x12x15 running 7.0's @ 188 mph.
So what is everyone running ? If you are asking about what you should run, as you can see, it depends on your combo, clearly if you are running a 355 ci SBC or a 526 ci blown alky BBC you will need different slicks, rim width, pressures, launch rpm, weight of car with driver, weight on the nose, height of wheelie bar, trans gear, rear gear, and converter.
I'm sure you have heard this before "it's the whole car combination".
Our driver, when he was racing his own JrFuel "A" car picked up almost 2 tenths by changing converters, nothing else. Kinda like the last piece of the puzzle, it let the motor run in the RPM range it wanted.
Jon Hansen, Hayden Wheels
JakeB23:
Ok, I wanted to update this post since I had some questions, and now I have some results.
I have a 225" FED that runs 5.40's in the 1/8th and 8.70's in the 1/4, (well, did atleast)
I started with 33 x 12 MH slicks, tried 7-9 psi, settled on 8, and car went 1.22 60's
I borrowed a set of 32 x 14 Hoosier's, tried 6-9 psi, settled on 7, car also went 1.22 (fastest)
I bought a set of 3069W 33 x 10.5 MT slicks. I thought the $269 a tire was reasonable, and at the time Hoosier 33 x 12's were 3 weeks out, and 33 x 12 GY's were a month out. I'm Impatient, and I wanted to stay with a 33" tire. Also I had used to run 28 x 10.5's MT (M5) compound on a 6.80's bracket car that didn't hardly need a burnout to hook, so I wanted to try them for my FED.
I tried 6-10 Psi and settled on 7. Car went a 1.18 60' Fastest 60' I've ever had, now I did have to slow down the shift this weekend to run an index, but I CAN'T WAIT to unleash this thing and see what it will run now!
Disclaimer. I don't know how old the MH or Hoosier's were, but there were both at least 3 years old. The Hoosier's I ran on a 15" rim, so there was definitely added weight for that wheel/tire combo.
Either way, I wanted to let everyone know my results as this is what helps people learn.
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