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T/S 368E
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Discussion Starter #1

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Discussing wheel speed tonight. The issue came up & guys had big differences in opinions.
What are most of you guys shooting for. How much does tire make change the sweet spot.
7.50 car with glide is what we were discussing.

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We recently went to M/T's from Goodyears, and the wheel speed graph is definitely smoother. We just went over the .25 and .5 into the run with a couple fellow racers at the track, and I cant remember them to save my life. I'll have to check.
The M/T's dont have the initial spike and then small drop off like the GoodYears did. Its more of a smooth, upward arc. We also changed shock settings slightly as well though. Ill post numbers when I have them.
Oh ya, 7.60 car with glide.
 

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T/S 368E
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Discussion Starter #3

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I don't want to mess up the replies, but the discussion started because of switching to M/T.
I run Hoosiers & we were discussing the difference since they changed.

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I am not sure if this is what you are asking, but we start from zero driveshaft speed to 1800-1900 rpm at .250, and 2800-2900 rpm at .500 into run to maintain wheel speed on an automatic car(bruno/lenco in the case in my car) It is a 6.70 altered roadster. I believe that these numbers are reasonably common for comp eliminator type automatic cars. We use a goodyear tire, but I believe we would look for these same numbers with any tire. I have no experience with other tires(I have been in the goodyear rut forever).
 

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I am not sure if this is what you are asking, but we start from zero driveshaft speed to 1800-1900 rpm at .250, and 2800-2900 rpm at .500 into run to maintain wheel speed on an automatic car(bruno/lenco in the case in my car) It is a 6.70 altered roadster. I believe that these numbers are reasonably common for comp eliminator type automatic cars. We use a goodyear tire, but I believe we would look for these same numbers with any tire. I have no experience with other tires(I have been in the goodyear rut forever).
That looks about 100 rpm higher then we were at,on our altered.
So I agree with you russ.that looks to be dead on numbers
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Dan
 

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T/S 368E
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Discussion Starter #6

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Thanks guys. The guys were far apart on opinions, so wanted more info.
To be honest, I haven't been out enough to find my sweet spot yet.
One insisted 1800 was fastest, one 2400, at .25 out.

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Is this how you guys look at it. Or do you look at the general shape, slope, and position of the driveshaft? For instance, how agressive the slope is in 1st? Or is this what your doing, just using those time markers as your reference? Great discussion.

Shawn
 

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T/S 368E
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Discussion Starter #8

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Just throwing out the numbers. They were going back & forth so fast, it was hard to follow.

I'm actually new to checking the numbers. My crew chief would worry about that stuff.
I had 3 guys go with last time, and that's where all this started. My wheel speed was way down with the new converter.
So the other night I brought the subject up with some guys from a 6.30, clutch car.
So I thought I would post to compare with some other guys. No one ever mentioned slope of the graph.
All I know is that 1800 & 2400 is a huge difference @ .25??

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I don't know if I'm doing it right either. I consider the slope of the graph for a particular track. For instance, under certain conditions, this is how aggressive I can get with the tuneup. Plus, I have a base for what I know the track can handle if I want to 'push it' I can try something and see if the track can take more.


Shawn
 

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As a rule of thumb. Somewhere between 1800 and 1950 @ .250 will usually get you the best 60s. Anything over that and your risking tire shake. The 10.5W tire is different and can take 2400 and 2500 @ .250 without shake. Of course the chassis setup has something to do with wheel speed and shake so I usually just start with a baseline of 1600 to 1800 @ .250 and then adjust timing and launch rpm until I find what the car wants.

The wheel speed @ .50 will vary depending on how much torque you have. My car for example ran a .971 60 foot time with [email protected] .250 and 2590 @ .500 but a 632 will not have the power to get the .50 speed without a shit load of nitrous so just pay more attention to the .250 and give the car what it wants.
 

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T/S 368E
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Discussion Starter #11

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We are pretty much all on a 33.5 X 17, no small tire guys in my circle.
The 2400 rpm guy is the most experienced, but slowest car in the discussion.
The majority said 1800 rpm. My car still had the 6.50 ET gear, and set up, so now with 7.50 ET power,
I'm trying to make the changes it wants. I welded up the crack in the housing & bought a new gear.
So hopefully we will actually get some real world runs in next time. Wheel speed was way low, 60' way slow,
chassis acting up last time out & didn't get any real usable information from such screwed up launches.

Thanks guys, with this little wimpy engine, I'll work on my .25 out and let it run what it will.

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T/S 368E
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Discussion Starter #15

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I actually took the 34.5 off 4-5 years ago when I switched to Hoosier.
Too much time, work & money to run A/PM, so I switched to T/S & didn't need it anymore.
I'm going to shoot for 1800 @ .25 with the baby engine & then start working on the chassis.
I really had trouble getting it to move last time out, and it was all because the 60' was so off.
Thanks.

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my magic number is 1850 .25 into the run not to worried about the .50 mark thats very hard to control in an automatic car. this is on a 1022 tire and let me tell you i leraned alot about tire pressure over the last few weeks, and have gone to a pressure i never imagined would work and it is doing very well i might add.
 

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Frank, can you describe "shit load"? I looked in my log book and I determined I didn't tune it correctly since I don't see that tune up term anywhere at any of the races we went to. What size pills are those? :-D
"Pills"... If you have pills then its not a "shitload":p. Ya gotta just take the pills comepletly out and let'er eat ;).

Hows the Motor coming?
 

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What I would like to know is how do you control it on a 10.5w tire car? I understand you can pulling timing but that is a crutch in my eyes. My car is already at 2 degrees of timing when the NOS comes on. Will lowering launch rpm helpwith the 2 step? or tightening the converter help control it more? what are you guys doing?
 
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