400 rwhp, 4.11's and 112 mph trap.. Taller tire??

alright, my tire is only 25.4" tall, ran a 12.5 @ 112 with a 1.75 60 ft time. Stock clutch and BFG dr's.

anyways, i really wanna cut down my 60 ft's so im thinking of getting an et street, it comes in at 26.5" tall. how many more mph would i roughly gain, and what would happend to my e\t assuming i run the same 60 ft?

would it be a similar time just with more mph?

shouldn't you be running better than 12.5? how is your shifting

my car is an auto that dynoed 305 with headers and intake,

ran 12.71 with a 1.88 60' at 109.88 8.1 1/8

with 400hp you should be in the high 11's with your 1.75 60'

maybe a slightly taller tire will help, what is your 1/8 mile time

i was hoping for 11's. i think my clutch was slipping a substancial amount, so i ordered a new one. was still on stock clutch.

here are my times.

60 ft - 1.7651
330 ft - 5.2278
1\8th mile et - 8.0591
1\8th mile trap- 87.17
1\4 mile et - 12.5009
1\4 mile trap - 112.00

that was only a 3600-3800 rpm launch. i kept braking loose or my clutch would slip if i went higher.

I bet your clutch is the problem. Stocker at 400rwhp espeically with the added torque of your mods would smoke that thing. I suspect your clutch is the issue, throw a new one in (not stock), break it in correctly and lets see where you are at. What clutch/flywheel did you order?

keeping my stock flywheel, and i ordered a Spec Stage 3+
i know lots of complaints but i have personally driven a z28 with a spec stage 3 and i was very pleased with it. so i felt it was a good buy.

and yea im really hoping the clutch was the only issue.

should i buy a set of et streets that are a bit taller? how long would they last as a pure track tire? i think ill burn up my bfg's in a hurry if i keep doing this. plus they dont stick as well as i wanted.

112mph trap seems really low, shouldn't you be trapping around 118-120?
I was trapping 109mph in my buddy's bone stock 02 WS6 last fall.

One of my friends had a 99 SS a few years ago with an LPE cam, LS6 intake, longtubes, 4.10's, Spec stage 3 clutch, and 315/17" Nittos, dyno'd about 380rwhp and was running 12.03 @ 118mph

the 315 is a taller tire. so the trap will be hire, this is my problem. my tires are too short. i dont know if ill hit 118 mph, that seems high lol.

i was hoping for a 115-116

The ET streets will grow in diameter slightly on the big end also if you think that helps any. What rpm are you crossing the line at?

As asked above, what rpm are you crossing the traps at and what at what rpm do you make max power? Those two should be close to maximize your track mph...And if you're using 17" wheels I'd ditch them for some 16" stockers at least or maybe 15s...More sidewall would help. too...espcially for a stick car...

--Alan

im buying 16" wheels off my buddy. and im trapping 112 mph at 6200-6300 rpm.. peak power was 6400 for me. 407.4rwhp.
peak torque was 5200 i think.

picking up 16" stockers tonight, and ordered a set of 26x10.5x16 M\T ET Streets.
lets see some 12.20's :) i hope haha

You're loosing a lot of et and mph thru clutch slippage. Fix it and see. I was trapping 120 with 4.10s in an A4 car with 27" tires. You should be able to do that with 26''ers with a stick.

i dont know if ill hit 118 mph, that seems high lol.


No, it's not. Not with 400rwhp.

yeah ditch the DR's and get a pair of good slicks. I have about 400RWHP and i got a crappy 13.2 @ 113 MPH w/ 2.40 60ft. Go with 27" tires and make sure your suspension is made to hook up

In your signature you say "lowered".....which typically doesn’t work well for serious launches. You need to make sure you're car is not squatting during the launch, which will really hurt your 60ft times. If so, you can add some LCA relocation brackets to compensate for the lowering.

Also, with the 4.10s you could run some 28” slicks, which will give you much better and more consistent launches.

WD

Anti-squat in action (1.50 60fts)!

http://shutter13.pictures.aol.com/data/pictures/09/008/7E/66/FD/80/-AbK8koNyU1YSjoKbdQCm1wkEYPu7Uk70300.jpg

i was under the impression that 28" tall tires would not fit on a lowered car, so i went with 26"

and i do have the lower control arm relocation brackets, set to the lowest setting.

engineer just curious, what suspension setup you have? (i.e. springs, shocks, struts?)

i was under the impression that 28" tall tires would not fit on a lowered car, so i went with 26"

and i do have the lower control arm relocation brackets, set to the lowest setting.

The clearance issues with 28" slicks are typically at the front and rear lip of the wheel wells at the rockers. And not with the top of the wheel well affected by lowering.

If you already have the relocation brackes and it isn't squatting, you should be good to go.

WD

engineer just curious, what suspension setup you have? (i.e. springs, shocks, struts?)

QA1 90/10 adjustable coil-overs up front w/ front sway-bar removed. Eibach rear drag springs w/ air-bags, Spohn adjustable TA w/ floor pan mount and adjustable Spohn Pan Hard Rod. Metco CNC aluminum LCAs w/ relocation brackets. Stock gas charged 50/50 rear shocks.

WD