traction and launching and gears oh my.

harvboi05

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i wasnt really sure where to post this so i figured id keep it all in house with the sn95 guys.

im getting my car setup for an outing at the track and etc. im rocking 3.73s, 27" tall 255x55x17 nitto invos on the stock 17x8 wheels. hardened 28 splines and a fresh trak loc. (ive seen cars cut 1.6s on those exact tires) poly mounted upper and lower control arms. stock t45 gear set. im never going to run slicks and skinnies, DD trim forever. im shocked with the amount of traction i have now, it isnt the smoke show like a fwd car i expected, second gear hooks pretty well, third dead hooks. makes me worried im not making as much power as i hoped. granted im probly leaving +50whp on the table with the lack of timing and how fat the fuel is, but i dont think that will make or break the amount of traction i have now. i guess its a good problem to have.

does anyone have an experience with 27" tires, 3.73s, ~600+whp (centri tq curve), and 7k rpm redline? i was hoping for 1.7x 60ft (hey, cut me some slack) and some 10.xx slips. the car should trap north of 130 in its current trim after i get it on a dyno and finalize the tune. 27" tires make that big a difference vs 25.75"? i know there are quite a few guys with 600whp centri setups, and this is my first rodeo with this setup. any advice for optimizing the current setup would be appreciated.
 

98 Saleen Cobra

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How you aren't breaking the tires loose with 255's is beyond me actually. The Invo's are not a drag tire at all and the typically spin from most people I talk to who have them.. What else is your setup??
 

harvboi05

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yeah im shocked with the traction too, hence my concern. i know theyre not a drag tire, but when i saw more than one person cut sub 1.7 60fts with a street tire that lasts 10k miles i was sold.

i forgot about suspension. kyb adjustable front struts, 14" 175 front springs, oem bullet rear springs and bilsteins out back.
 

98 Saleen Cobra

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That doesn't seem right, but hell run it at at the track and see what it traps.. How much power are you making?
 

harvboi05

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Trust me I will. Idk yet, no dyno/track time yet. I'm hoping to trap well over 130 with minimal weight reduction, so +600.
 

98 Saleen Cobra

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Sorry bro, IMO you are making no where near 600rwhp.. You'd be blowing those tiny tires off going into 4th lol.
 

harvboi05

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I'm still working on things so I'm not too concerned yet. Just hoping to find out how tire height vs gears and etc comes into play.
 

itSSlow98

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Sorry bro, IMO you are making no where near 600rwhp.. You'd be blowing those tiny tires off going into 4th lol.

I agree, i wonder if your clutch isnt slipping. 255s, let alone street tires simply wont put that much power to the ground. Hell my brother has 295 Invos on his 2011 Gt making 410 and he'll spin to 50mph.
 

harvboi05

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this thread isnt going in the direction i hoped, but for what its worth, my car hooked in second on stock 245 radials before the rebuild and it made ~475whp. i still have a lotta kinks to work out, and finalize the calibration.

im hoping to confirm that a 27" tall tire is more/less than ideal for a car with the ETs and trap speed goals i have in mind.
 

98 Saleen Cobra

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Sorry buddy. Yes to answer your question with a 27'' tall tire and 3.73's you'll be able to trap will into the 130s :D
 

harvboi05

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thanks for your input.

i was hoping to hear from some people with more drag experience as to if that is an ideal setup. when to use 26/28" tires, etc etc.
 

98 Saleen Cobra

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Well really you want to optimize your gearing and tire sizes for your max trap.. There is also how much sidewall you need for traction too. Some 26'' DR's will still get blown off with the power.. I think that either a 26'' or 27'' tire will be just fine for your trap speed with the 3.73's
 

harvboi05

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max speed in 4th should be way over 145, so its not like ill run out gear. i think i got a lil bit too tall a tire.

sidenote: i forgot about the extra 150lbs of tools i have in the trunk right now incase i break down. that will help traction. lol.
 

98 Saleen Cobra

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Yea throwing a 150lbs of tools in the trunk def helps with traction hahahaha.

Yea you got to tall of a tire.. You can either get a 26'' tire or up to 4.10's and keep the 27''.. BUT I'd say the first one is cheaper hahaha.
 

harvboi05

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i have a full carry kit of 1/4, 3/8, and 1/2 rachets sockets, breaker bars, oil, coolant, wood blocks, tons of shit! haha.

the funny thing is, now my speedo is 100% accurate. id rather have to launch harder than softer so i guess im where i intended on being.

do you have 4.10s?
 

98 Saleen Cobra

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I do have 4.10's.. If I were to drag my car I'd pretty much need a 28'' tire with the power/weight/gearing that I have..
 

harvboi05

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man i woulda bet money you had 3.73s. i like to dabble in roll racing too, so i figured 3.73s would be a good all around gear.

id like to see what kinda results drag guys get with 3.73s and with what size tire/power level theyre at. hopefully some more people chim in.
 

98 Saleen Cobra

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Yea the 4.10's are little much but they are growing on me more and more.. When I street race which is pretty rare, I don't have to worry about a T/S car jumping out on me.. The race ends rather quickly at 127-30ish.. vs 145 like most people like to run which to me is a little safer lol.

Don't get me wrong if I had 3.73's I wouldn't change them. I've been thinking about switching to 3.73's when I hit up the road coarse again. But right now the 4.10's are fun on the street and they get the job done. :)
 

harvboi05

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i just calculated the difference between tire height on stock tires vs my 255 55 17s, and it increase the speed capabilities of each gear by 13mph! in comparison 275 40 17s increase speed capabilities by less than 1mph. i didnt realize how huge a jump that is. i essentially lowered my final drive to 3.42, or ~10%. that would definitely help increasing traction. i have yet to take the tools out of the trunk and verify their effects either.

just posting up some info in case some one stumbles upon the thread in the future.
 

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