Got another one

Technical Assistance for Super Pro and other non-junior related Drag Racing Classes

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Got another one

Postby Pool Man » Mon Jan 07, 2008 9:21 pm

I have been noticing that a number of race cars have different size tires. Most of the cars that i noticed had simuliar ET's. Why such a W I D E range in tire sizes? Is it due to the different chassis set ups? Like, leaf spring, ladder bar and four link? Is it the chassis and its set up that dictates the tire size?
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Postby Emily's Dad » Tue Jan 08, 2008 9:15 pm

Certainly cant speak for everyone’s decision, but…

Most bracket racers will set up for "dead hook", aka NO SPIN

There are some cases (Comp and P/S especially) where you will set up for a balance of controlled tire spin and least amount HP loss from tire size…..
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Postby Pool Man » Tue Jan 08, 2008 9:55 pm

But, that does not explain why bracket cars run such large tires. I have seen 10.5 inch tire cars run in the low 5's with those tires. Why do racers always run much larger tires than IMO they really need? Is it due to poor chassis set up or just in case they hit a bad track and may need more tire? Which make no sense to me. I am talking abt. door cars here. Not dragsters.
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Postby Emily's Dad » Tue Jan 08, 2008 10:04 pm

Bigger is better.......right


smiley-hug
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Postby Emily's Dad » Tue Jan 08, 2008 10:09 pm

With an exception of the very high end 10.5 tire cars….most are a case of border line insane ….these dont even fit into the "controlled spin" category….maybe the "uncontrolled spin" ……if one of these 10.5 cars go back to back numbers its generally shear luck.
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Postby Mindbenders5 » Tue Jan 08, 2008 11:06 pm

Before i sold my chevy II to go jr dragster racing with my kids I ran a 10.5x31w m\t rear tire. And my car would drag the rear bumper every pass. I think its just what you are cofortable with and what the car was built for. Most full body bracket cars are built for a 14x32 rear tire so thats what alot of people run
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Postby Emily's Dad » Tue Jan 08, 2008 11:43 pm

Dragin the bumper AND running low 5"in the 1/8???
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Postby Mindbenders5 » Tue Jan 08, 2008 11:48 pm

NOOOOOOOOO!!!!!!!!
ran mid 6s
but it was full body. full interior. So it was fast enough. The only thing i cant figure out is why I spend more on a one cylinder engine than i did my last small block!! LOL smiley-lol
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Postby Pool Man » Wed Jan 09, 2008 8:20 am

The tires in Traivs' El Camino are 33/15/15 Just seems like way to much tire for the car. Car should run in the mid to low 6's.
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Postby Emily's Dad » Wed Jan 09, 2008 8:25 pm

I wouldnt fret it....add a little air, back off on the burn out and have fun.

Unlike converter's smiley-laughing when it comes to tires, too much is BETTER than not enough.
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Postby 3dracing » Thu Jan 10, 2008 11:55 am

Ron most of the 10.5 guys around here run the MSD Digital ign. and the just plug in the laptop and re-program the timing and settings they want, leave soft and pull hard. When it gets hot and greasy at our local tracks in the summer that are fudging on the track grip, can you have to much tire?


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Postby Pool Man » Thu Jan 10, 2008 2:05 pm

I just want to run the smallest tire possible without sacrificing traction. Without going trough a process of ellimination with diffrent size tires. Like i said, i have seen many, many cars running the same ET. Some with relatively small tires and others with huge tires. I was trying to come up with a way to judge what size tire is needed. Rather than just throwing a big set of tires and saying that is good enough. Would rather get away with running a smaller tire if i could.

And yes, you can have to big of a tire. We proved that with Brians dragster. Cost him abt. $6,000 to learn that lesson.
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Postby 3dracing » Thu Jan 10, 2008 4:24 pm

What cost $6000?


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Postby Pool Man » Thu Jan 10, 2008 5:13 pm

All the transmission casing, heim joints and tabs he had to get welded back on the chassis after the tires shook everything possible.
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Postby dragracer2757 » Thu Jan 10, 2008 9:19 pm

how much power and what size tire in the digger ,, usually shake is from not enough power(wheel speed) just curious
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Postby Emily's Dad » Thu Jan 10, 2008 9:22 pm

Scott knows.....

Guessing only at the end of the burn out???

Ron not sure if this is "the" cam for you, but its close.....look up a Comp Cams 304CR8, and quit sweating the rpm thing......
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Postby Pool Man » Thu Jan 10, 2008 9:28 pm

468 cid steel block and heads. Hyd. lift cam. That was exactly the problem. Not enough power for the tire. That is why i say you can have to big of a tire. I tried telling Brian for well over a year that he had to much tire for the engine. Everyone at the track kept telling him " you can never have to much tire". So, guess who was wrong? That's right. DAD.

This is why i am now asking the question for Travis' car. Even though it is a door car and has line lock, i still would like to install a tire more suitable for our application rather than just put any old tire on it. If i do over size the tires how much will it hurt the performance of the car?
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Postby Emily's Dad » Thu Jan 10, 2008 9:43 pm

So you are saying that the car "SHOOK" at the hit? During the run? or was it only on the burn out?
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Postby Pool Man » Fri Jan 11, 2008 12:17 pm

It would shake vilently on the burn out. Then, the tires just break loose at the launch or shortly there after.
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Postby drags3078 » Fri Jan 11, 2008 9:05 pm

is this a powerglide or 3 speed transmission ??..... quit putting hydraulic cams in race engines .... it least put solids in for the minium , you pull another 1200 to 1500 rpm over a hydraulic
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