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-   -   ET Street's Best 60' PSI? (https://www.rx7club.com/rotary-drag-racing-167/et-streets-best-60-psi-946218/)

Bacon 03-17-11 06:35 AM

ET Street's Best 60' PSI?
 
SO i know every day will need different pressures to get the best 60 depending on the conditions that day. but where do you start dialing in from?

I was able to cut 1.48's & 1.50 at 16 psi, but some of the rednecks at the track said they were hooking best at 12-14, and never go higher than 14. now their launching at much lower rpm, but have way more torque, and traction is traction right?

Really wondering what the guys cutting 1.30's and low 1.40 start dialing in from and is it just a .5psi or 1 psi jump till you see chnage in the 60'

ohh another think killing me is no 2 step yet, so im just free reving and dumping

enzo250 03-17-11 09:43 AM

You'll have to play with it and see what works best for you...

I've had best luck with 9~11psi.. although it will be a fun ride!...

I would start around 12 and keep lowering it till it becomes to unstable on the top end.

tom94RX-7 03-17-11 12:13 PM

You also lose top end speed with lower air pressure. I run et streets and usually take them down to about 11 or 12 and always get good traction. But last time out I had it around 14 psi and it must have helped me get better trap speeds but I was not launching good, not because of the tires though.

Now I got 2 step and will be launching with 5-10 pounds of boost and also wondering what psi I should start out with, was thinking maybe start out with 15 psi cause I'd rather have the tires break loose off the line than break something, but Idk I'll have to play with it.

sk8world 03-17-11 12:45 PM

I used to run 10-11psi. Last year I decided to leave it high to start. 13psi. First run was 1.43 and second was 1.39! I would guess that to be the record on a stock axle fd? This was also on my 10.5 not the 11.5's.

ultimatejay 03-17-11 03:54 PM

Also remember, the more you hook the more your going to start breaking driveline components and that sucks when you dont' have a trailer.

Bacon 03-17-11 04:59 PM

1 Attachment(s)
shees a trailer queen, so far ive eaten 1 tailshaft & 3 inner axle cups, but learned lessons form every part, changing to a sprung clutch helped alot, tailshaft brace, the last axle cup was my fault :)

https://www.rx7club.com/attachment.p...1&d=1300399077




Originally Posted by ultimatejay (Post 10522441)
Also remember, the more you hook the more your going to start breaking driveline components and that sucks when you dont' have a trailer.


sk8world 03-17-11 05:18 PM

Damn son.. Thats car is gutted! I want to get lighter but my car is in too nice of shape to rip it all out.

I quite worring about breaking parts, part of racing. You preload the driveline and most all that goes away.

turbo10th 03-17-11 05:39 PM

I usually run 13-14psi and have managed a best of 1.45 but pretty consistant 1.5-1.58's foot reving

Bacon 03-17-11 07:57 PM

1 Attachment(s)

Originally Posted by sk8world (Post 10522580)
Damn son.. Thats car is gutted! I want to get lighter but my car is in too nice of shape to rip it all out.

I quite worring about breaking parts, part of racing. You preload the driveline and most all that goes away.

LOL yea, if i could do it all again I would have kept the interior. and a lot of other things. Ive owned this one since 96 and when I wrecked it this was the direction I wanted at that time, 2 bad my turbo is tiny, my ecu is outdated but hey alot has changed since my last power adder purchase.
https://www.rx7club.com/attachment.p...1&d=1300409762





Gonna start at 14psi tomorow as that seems to be a good starting point and see what the night holds!!!



If your not breaking your not trying hard enough

Judge Ito 03-18-11 07:01 AM

keep in mind that when u lower the tire pressure under 10psi the car will try to sway from side to side in top end. a little scary.

turboR1 03-18-11 10:19 AM

7-9psi is where I hooked the best, but that was on junk 5 yr worn et streets. I would start at 15psi and work my way down until its too scary for you lol. just make sure you dont mix and match the radial and bias ply tires it will make the boat sway a lot worse.

Trots*88TII-AE* 03-18-11 12:55 PM

Just to but in, what kind of pressure do you run in front bias ply tires? I've got Firestone cokers on spares.

sk8world 03-18-11 02:02 PM

I over in flate mine. thinking its 40-45psi I run. I have never tried 15psi in my et streets but going to give that a try next time out. If the track is on kill mode then pump them up!

sk8world 03-18-11 02:04 PM

https://www.rx7club.com/attachment.p...1&d=1300409762





Looks like the tree-pole won... Damn... That would make me cry!

Bacon 03-18-11 02:52 PM

LOL, yea the pole won, funny thing is poles are only like 350$, but overnight emergency install was 1000$ in labor, thank god for insurance.

Skinnies in front are moroso DS2's i run @ 30 psi as it says max press 32 psi on sidewall of them (heat expansion)

Ive tried the biasply/ radial missmatch, so i know that wobble on the big end all 2 well- Tminus 2 hrs till track time!!!!

sk8world 03-18-11 03:43 PM


Originally Posted by Bacon (Post 10524120)
LOL, yea the pole won, funny thing is poles are only like 350$, but overnight emergency install was 1000$ in labor, thank god for insurance.

Skinnies in front are moroso DS2's i run @ 30 psi as it says max press 32 psi on sidewall of them (heat expansion)

Ive tried the biasply/ radial missmatch, so i know that wobble on the big end all 2 well- Tminus 2 hrs till track time!!!!



Good luck, let us know how it goes. I may go saturday. Only 5 minutes from my house!

Bacon 03-18-11 10:28 PM

Well 14 psi was worlking well, i was launchin like a puss since its been 2 years, cutting 1.80's but when i dropped to 12psi, that and 7k ate another inner axle cup- owell i needed somehting to do sunday

mazda rx2 rotary 04-09-11 09:32 PM

A little run down of my experience!!I ran a set of 28X11.5X15 slicks and ran mid 1.20 sixties all day long.i drive my car on the street alot slicked down with the wheelie bar.I put a set of ET streets 13.5X28X15 and lost a tenth of a second off my sixties.no matter what I did I could never get back to the mid1.20s.I sold the ET streets,slicked it back down,and to date I have ran a 1.24 sixty with the slicks,with the ET streets the best was a 1.34!!!

1sgen 04-10-11 12:13 AM

13 to 14psi was the best for me , 1.44
i went down to 12 and front end started moving around toward the end of the track

Indian 04-17-11 09:43 AM

hey guys.. are these tire pressures cold or hot?

beefcake 04-17-11 10:16 AM

cold as you dont get much time to test it after a burnout . unless your going roundy racing

Indian 04-17-11 10:41 AM

thanks Beefcake.. not sure if some of these measurements were recorded between runs or sometimes people drive to the track with them and adjust them before cool down

beefcake 04-17-11 10:49 AM

it would be best if you got a trustworthy mate to be able to check your pressures just before you enter the staging zone, as your temps can rise or fall depending on time of the day, our rh side slicks always get hotter as the sun is in the afternoon , and we always have to drop the rh side tyre to balance it.
Usually between runs its cooled down enough to have cold readings, but you should check it in the staging lanes as good practise as thats the last time you can get it the same

Indian 04-17-11 11:00 AM

good info beefcake. Thanks

Bacon 04-17-11 07:56 PM

Nitrogen..... temp becomes nearly irrelivant


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