Tar Heel

I've done a search but come up with lots of tires except MT. I have 275/40/17 drag radials and will be going out Saturday for the first time on them. The car is an '04 with CAI, Yank SS4000, 3.90 and a good tune. Dyno numbers were 326rwhp. If the air is good there is a chance that the DA could be below sea level (Dallas Raceway in Crandall) and I'm hoping to go high 11s but that may be optimistic. Any ideas where to start air pressure?

Thanks!

2blackvette

18-20 psi, thats what i used at the track, m/t et street radials, yank 3600, cyl heads,cam, headers,x-pipe, 4:10rear car ran consistant 11.3's, that should at least put you in the ball park. good luck, andy

chaase

Start at 20psi and do a run. Drop the pressure 1psi and run it again. If the 60' times get better, then lower it again. If you get a worse 60' time, then go back up 1psi.

Every car is different but for my car, 18psi cold worked the best.

Tar Heel

How much of a burnout do MT's require? I've been out of racing for a bit and can't remember how much they like or if I need to do a John Force on the first one since they're new.

chaase

You don't need to go insane with the burn out. You just need to get them hot and enough to stay warm until you launch. I would do a longer one when it was cold outside though. They wouldn't stick right if I didn't.

dankhts

Mine seems to hook up the best if I burn out from 1st to 2nd with the line lock on until I see the white smoke...also 19 - 20 psi works best for me it seems...they'll prob hook a bit better after a heat cycle or two...

123sugey

If track prep is stout or even ok .. Maybe 20 psi. Don't worry about the DA where you are. Figure out from the first pass what your car may need. Don't forget that you need to figure out what to launch your car at. That will come with time

algZO6

17.5 cold works for me

Tar Heel

Thank you. The only reason we keep an eye on DA is that we'll be attending a points at the same track next month and we have to run a 12.45 index or better. We'd like to collect some data Saturday to give us a baseline as to where we'll be when we return for the IHRA Pro Am.

Great point about where to leave at regarding RPMs. This is my first rodeo with the C5 but from previous bolt-on cars they reacted best when I left just above an idle and let the converter flash. However, those weren't IRS cars so this will take some TNT'ing to figure out what it likes best. I can't wait to see how much the gear, converter, tune, and DR helps it out. The only time we've had the car down the track was last spring when it went 13.39 bone stock and even had our luggage in the trunk!

RonSSNova

My guess is that since you will be bracket racing, is that you will need to adjust your leave rpm in order to cut a light.

Hopefully, you can leave anywhere between high and low and still hook up.

From the datalogs I've taken with HPT, there is a delay between the pedal and the throttle. It's not a lot, but will figure in the whole deal as well.

Good luck.

Ron

Tar Heel

18.5 seemed to work fine although truth be known, changing it from 20 all the way down to 17.5 didn't change the 60' hardly at all. It stayed between 1.62 and 1.60 on every pass and the ET was between 12.35 and 12.30. Also, I left from about an idle and flashed it when the tree came down. I tried once "pushing" the converter a tad to about 1500 or so but wasn't sure how good the track prep was and didn't want to push it through the tree and red light.

TA

You can't just pick a pressure and assume it will be the best pressure for all weather/track conditions. There are warm days when the track is prepped well that I I can hook at 24 lbs or so. On cold days with bad track prep I've had to as low as 14-15 lbs to hook. Normally I start at about 21 lbs or so and adjust up or down accordingly based on results.

And BTW, I have about the same RWHP as you do and run high 11s fairly consistently.

Tar Heel

Thanks. What type of weather conditions and DA are you running high 11s in on a regular basis? If is was similiar to mine and I was going 3+ tenths slower I have issues.

TA

I run at Atco and Etown which are probably two of the quicker tracks in the country. They are both just above sea level and see very low DAs in the early spring and late fall.

Tar Heel

Thanks. I assumed that. My DA was 1800+' and we literally had a 30mph wind coming straight down the track. I think in perfect air on a well-prepped track it has an 11 in it. I'm going to order some AR headers to make a little more power and some Bogarts to lose some weight and hopefully those two items will help.

We'll get there ...

TA

Just come to the east coast in November and you'll get your 11

Tar Heel

I used to live to Eastern NC and raced at Coastal Plains in Jacksonville, NC. That place was a mineshaft! I believe it's listed at sea level for it's elevation and it wasn't uncommon in the spring and fall to be -1000' DA.

Dallas Raceway in Crandall, Texas is my home track and it's 500'. We get decent conditions early and late too.