Drag Racing Discussions > Rear Engine Dragsters

RED setup

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773077:
I tend to agree with you regarding the wheely bar. I may have to use it as a crutch to get the car to leave properly, but personally don't care for them. I think you can get most slicks, within reason, down the track by manipulating launch rpm and timing, the question is: is that the ideal combination for the quickest ET. I also tend to agree with you regarding radials on a dragster. You'll not find the answer in 1 or2 laps down the track, it may take hundreds. My thought is how do you make them work? We use the bias belt slicks and spin them just enough to get the car moving and the correct wheel speed for that combination. Radials don't like spining and have a poor recovery. You would like the tire on the edge of breaking loose all the way down the track. Take a C/ED short deck sbc that is 307 ci and makes 800 hp vs this combination. The power to weight ratio for the C/ED would be .521 while B/DA  combination would be .668 both at the same weight. Both classes of cars have run the same tire, 12x33x15. What did they have to detune to get that tire to work on the B/DA car. I have some thoughts about radials but would like to talk with someone who has tried them to see what their experience was. Any thoughts on tire pressures and adjustments. How much tire pressure have you run. We used to have a combination that would get the car down any track: 7 lbs of air pressure, 5,000 rpm launch, take 12 degrees of timing out for 1.2 seconds. Thanks for the response.

masracingtd1167:
We have run them on a comp car but it is a bodied car with a 4 link . We have gone fast on them but only on a track with national event conditions . A dragster FED or RED needs wheel speed to go quick . We also crashed the car with the radials and to this day we really don't know what caused it . After the car was repaired we only went to one race but we put the bias tires on it and set the record on the first pass.That 12x33 tire is very fast and will work for you but the 14 might make the car a little more stable .With a thousand hp you should easily run in the six's ! It shure will be an eye opener ! 

773077:
I tend to agree with all that you have said. The radial was developed for cars with suspension and a RED has virtually none except chassis length and tires. The whole issue is getting it off the line, as the tires are built to dead hook and if you break them loose they may not recover. I think it still has to do with tire management in the first 5’ or that first .5 seconds from transbrake release. Lets say it takes .15-.25 seconds from brake release until it hits tire. At that point the bias slick is wrapped up and starts to spin about 1-2 turns before it catches and leaves on the edge of breaking loose. The radial on the other hand dead hooks and spins and catches itself or driver pedals it, in any case, lets say it recovers but to much time is lost to post an acceptable time.  My thought is that you would want to manage that point in time at launch as it starts to spin that 1 1/2-2 turns to allow the tire to recover, get up on the tire and hopefully have enough wheel speed to continue the launch without breaking the tire loose (kind of like a super comp launch but not quite, a pfft+). If this was the case, I think you would want the softest compound, widest tread and the lightest radial you could find. I would also think about swapping out the legal ignition and plugging in one with traction control (test only) to see what the rpm, trans output shaft rpm and wheel speed needs to be to launch successfully. Having said all this it could very well indicate that you need a different converter or tire and compound and rear gear to make it work on a RED. Sounds tedious, but interesting. Thanks for the info. Anyone else have some insite and want to share?   

ricardo1967:
Doesn't the track surface treatment (VHT and such) play a big role here?

773077:
Yes, of course, as well as the weather, engine power aviabable, tire pressure etc.. If the starting line is junk the bias tire probably won't do well either and you'll have to detune. A good tool to use is your experience. Walk the track along with crew chief before competition starts, Grade the track and starting line on a scale of 1-5. Crew Chief checks starting line again before burnout and sets final air pressure. After burn out crew chief grades the the starting as he guides the car back to starting line and sets launch rpm if its different than you predicted. If you are at a national event try to catch one of the top fuel guys when they are evaluating the starting line. I think with your experience you could add a bunch more. Be consistant in your preparation and remember you are racing the track not the guy in the other lane. 

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