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Discussion Starter #1
I was running 11.7 1/4 7.4 1/8. I am running a 408 stroker 499 pounds torque at 3600 rpms 501 HP at 5630 rpms. The old rears were 3.42. Everyone said go to 3.73 or 3.90 and ets will improve. Well I went to a 3.90 and the best time today was 12.1 and 7.8. I think I have got out of my power curve with the 3.90 gears. Any thoughs?:(

tumblebug
 

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What were your old 60ft. times and your new ones? You may be spinning a little more off the line now.
 

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your 1/8 should have improved with the gear change, but your 1/4 would have been slower and down on MPH if your were out of your power curve.
As stated above you might be spinning off the line. The first 60' are soo important.
 

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Discussion Starter #4
spinning

I think your right about spinning. I just looked a some old time slips and 60' were always in the 1.6s. Now there in the 1.8s. I am running 28-9-15 Hoosiers. There not even 1/2 wore out. The reason for changing the rears was that I wanted to cross the finish line at peek HP rpms. I think my torque starts dropping off at 5000. With the 3.42 the car was pulling all the way through eventhough I was barely shifting into 3rd at the end of the track. I guess drag racing is as hard to figure out as women.:confused:

Tumblebug
 

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I guess drag racing is as hard to figure out as women.:confused:

Tumblebug
no, there are equations for drag racing that can help you figure things out. with women, you're stuck to 'feelings' and other things that we can't quite comprehend...
 

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depending on converter you should be under your peak HP with a 28" tire and a 3.90 gear. but if you 60' slowed down its most likely traction issuse. what do you have for traction control in the rear? and what air pressure did you have your tires at? i ran the same tire on my car and they seem to like 10-11 psi max.
 

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You have to consider the weather as well as the traction issues. When it gets hot your motor will be down on power. The air is just not able to support much HP plus it heats up your fuel and takes HP out of it. And heat makes the track slicker. Add to that the age of your slicks. Tread depth has nothing to do with how well a tire works. Age reduces the softness and stickyless of a slick.
 

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Discussion Starter #8
all of the above

Thanks guys for the input. I think it's all of the above. I was running 17 pounds in the tires, and they had a street car competion that was eating the rubber off the starting pit. It was also hot. I think I will go back to the 3.42. It only takes about a hour or so to change them out. My top end went from 119.8 to 113.6 I would like to go to maybe 3.55, but money is tight and times are hard, and my wife's foot doesn't fit well in my rear end. (Not car rear end).

tumblebug
 

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Personally, I don't think your tire pressure is the problem. I know I run MT slicks, but I run mine at 16 psi no matter the conditions. My car weighs 3335 with me in it and the engine makes pretty good power. My 60's are always consistent.

I'd be interested in what u have for traction aides on the car as well. That gear should work well, so u might have exposed other issues with the swap, such as chassis set up, or converter.
 

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what cam , converter ???

what cam is in it ??? if you use a cam with more topend and a cam that will rip through its range faster , thats when a bigger gear will help ya , IMO,, if your motor peaked at 5600 and had 500 lbs of torque at 3600 ,,, you might get more out of a converter change than a gear ,,, but thats more $$$$
 

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leave the gear in it and make the car work. Get the 60fts to drop then the ET's will come down too. Your mph is an indicator of HP so if the ET is good but the mph is down there is a problem.
 

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Discussion Starter #12
cam & converter

comp cam hyd roller Duration 236 in 242 ex Lift .555 .576
converter B&M nitrous hole-shot 3000 stall
 

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I guess drag racing is as hard to figure out as women.:confused:

Tumblebug

Thats one of the smartest statements I have seen in a long time!!!!!
 

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Discussion Starter #17
power down

Yes, my son was videoing from the stands, and he said I was not coming off the line nearly as quick. The car is coming off the line at or around 2800. I was so sick about the down time I only ran 3 passes. But, every pass was a little faster. I may go back with fresh plugs and wires and try shifting at a lower rpm before going back to the 3.42s.

tumblebug
 
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