Improving My 1/4 Mile Time...

[klenn]

Hey guys run my car down the 1/4 last week for the first time wasnt very happy with the result came out with a best time of 14.8 which to me seem pathetic to my mods, correst me if im wrong!

my car is making around 180rkw mods are

adjustable boost set 12psi

walbro pump/adjus reg

foward facing intake

fmic

adjustable suspension similar to teins quite stiff

goodyear f1 tyres with good tread

manual with standard clutch- clutch not in the best cond but dont think it slipped

To bare in mind also the whole boot is taken up by sounds which could weigh a bit but not enough to make my 1/4 this crap surely?

There were alot of other skylines and cefiros with less mods than my car and way craper tyres pulling alot better times than me but the one thing i noticed is their cars seem to squat down and launch but mine just sorta wanted to sit on the spot then slowly move foward if you get me.

ANY help or ideas would be much appreciated, id like to atleast crack the 13's!

[Nismo_God]

mate it is a lil slow, my stock s2 33 with only turbo back makes 169rwkw and my best pass on slicks is 13.426 and on 19x10 street tyres i got a 13.700. should be at least running the same as me with those mods and power...

im going to the wsid, u live in sydney? come down and we can chat

[GTshortie]

Klenn, If you could give us the rest of the details that follow with the 14.8 ET you ran like:

60ft (indication of how good your launch is)

Trap/Terminal Speed in MPH (indication of how much power your making)

Along with your ET these figures prove valuable in giving you better advice on where you can improve.

What size rims/tyres where you running? 16/17/18" 225/255 wide etc.

For you information:

I was previously running consistent 14.2 and a best of 14flat with around 190-210rwkw and getting 60ft's of 2.3-2.5 trap speed of 103-105mph this is with my heavy 17" sparcos running decent dunlop tyres 255 width at the rear.

I then switched to my r33 stockies 16" with good toyo t1r's in 205 width only tyres, and straight away i got:

consistent 13.6 ET with best of 13.5 ET same trap speed of 103-105mph but my 60ft improved to a 2.0-2.1 as opposed to 2.3-2.5 I was SHOCKED! and was trying sooooo hard to break into the 13's..

my 2c

[Fixxxer]

As mentioned above, what was the 60ft time?

Do you get wheelspin off the line, or bog down?

A good set of tyres will help rub off lots of ET.

[benm]

Hey guys run my car down the 1/4 last week for the first time

So you went for the first time, worked out how the whole night runs and made it home with the car in 1 piece... well done!

Now go back again (or for the next 6mths if you have to) and practice practice practice.

[2rismo]

Now go back again (or for the next 6mths if you have to) and practice practice practice.

Quoted for truth!

[klenn]

Klenn, If you could give us the rest of the details that follow with the 14.8 ET you ran like:

60ft (indication of how good your launch is)

Trap/Terminal Speed in MPH (indication of how much power your making)

Along with your ET these figures prove valuable in giving you better advice on where you can improve.

What size rims/tyres where you running? 16/17/18" 225/255 wide etc.

ok guys cheers for your help so far,

hope these are what your after

60ft-2.462

And speed- 93.97mph

my tyres are 235/45/17 with good tread.

any more info you need please let me know cheers.

[klenn]

As mentioned above, what was the 60ft time?

Do you get wheelspin off the line, or bog down?

A good set of tyres will help rub off lots of ET.

as for wheelspin it sorta felt like 1st gear didnt get me anywhere i could be wrong but it felt like it topped out really quickly like it was wheelspining, i think thats part of the problem the back wheels are already 2 or 3 fingerwidths inside the guards so when i go to pull away i dont think it can bog down because of the stiffness on the bum????? also i didnt let any of my tyre pressures down which could of helped me i suppose.

[`nigno]

So you went for the first time, worked out how the whole night runs and made it home with the car in 1 piece... well done!

Now go back again (or for the next 6mths if you have to) and practice practice practice.

Quoted for truth!

+1.

Experience shaves a lot off your time too Its a little tricky getting used to how a car hooks up and takes off at a drag strip. Trying to find the optimum way to launch and accelerate and a good tyre combo isnt something most people get right on their first ever try. Keep at it, guaranteed with experience you will lose tenths off that time at the very least.

[CEF11E]

this might be a silly question but, will your ET's improve with just stock rims/good tyres on the rear?

Also given full stick with 215/45/17's on the upchange to 2nd i am getting wheelspin all the way to 3rd will lower pressures stop this or will I also need to be lighter on the change?

[GTshortie]

Based on:

'60ft-2.462

ET 14.8

And speed- 93.97mph'

The general rule of thumb for 60ft's is for each 0.1 you reduce your 60ft by you shave off approx 0.2 off your ET.

So in your case just with practice you should be able to get your 60ft down to 2.0-2.1 after some more runs and by dropping(adjusting your tyre pressure). HENCE in the current form you should be able to net a 14flat given you run an approx 2.0 60ft.

I suggest:

-Empty OUT your boot!, esp the sound gear + spare tyre/tools/jack

-Run 30psi tyre pressure in the rear tyres and drop it through out the night and monitor your 60ft to see if you improved or not <don't go lower then 20psi at the bare minimum> THERE isn't a tyre pressure pump at WSID so you'll have to pump it back up on the way home.

Do that and PRACTICE, PRACTICE PRACTICE + PRACTICE and you'll see results your asking for

My mate in his twin turbo supra the first time out a few weeks ago with 214rwkw ran a 14.4 and best 14.2 with average 60ft of 2.3+, THEN we headed back on wednesday 21st DIDN'T change anything at all, first run FLUKED a 2.0X60ft and got a 13.7 the rest of the night he never saw 13's ago lol BUT he was still alot happier.

my 2cents

[Fixxxer]

Stock rims and a good set of tyres will improve your times a great deal (they are usually lighter aswell). The old rule is that if you can go 0.1 faster to the 60ft mark, you can double the savings at the 1/4mile. So if you go from a 2.4 60ft to a 2.1, you'll be well on your way to knocking over half a second off your 1/4 mile time.

CEF11E - Take some pressure out of your tyres, 25psi would be a good place to start, then lower it by 2 or 3psi if your still not happy (make sure you bring a portable air pump to pump them back up for the drive home). I wouldn't go much lower than 18-20psi on normal street tyres. I run 13psi on slicks.

The more traction you have the better (as long as the clutch holds up). You can leave with more boost too A good few free revs prior to launch will see you leaving with positive boost pressure.

Fixxxer

[2rismo]

A good few free revs prior to launch will see you leaving with positive boost pressure.

Fixxxer

Sorry, not true. Not possible in a manual at *this* level. Free revving the car before leaving the line is a very silly way of working out what type of launch revs suit your car. Experiment with holding the throttle at different rpm and work out where you're quickest to 60ft.

[klenn]

Sorry, not true. Not possible in a manual at *this* level. Free revving the car before leaving the line is a very silly way of working out what type of launch revs suit your car. Experiment with holding the throttle at different rpm and work out where you're quickest to 60ft.

I was just about to ask the same question so what your saying by having positive boost is to sit at the line idling then just put your foot down and let out the clutch at a certain revs so the cars on boost OR to sit at then line holding i suppose the 3-4 grand mark and then releasing the clutch as well as putting the foot down??

[klenn]

Thanks for your help so far guys,

So you guys are stating tyre presure is crucial but what about suspension does this not have a big impact on my current setup-does my car not make enough power to be worrying about the suspension for traction ect??

[2rismo]

I was just about to ask the same question so what your saying by having positive boost is to sit at the line idling then just put your foot down and let out the clutch at a certain revs so the cars on boost OR to sit at then line holding i suppose the 3-4 grand mark and then releasing the clutch as well as putting the foot down??

You won't have positive manifold pressure until your car is under load and you're off. The best you'll see on the start line is very little manifold vacuum - not boost. Just do it the way you described in your last sentence above and you'll be fine. Don't worry about tyre pressures or suspension for a while.

[Fixxxer]

Sorry, not true. Not possible in a manual at *this* level. Free revving the car before leaving the line is a very silly way of working out what type of launch revs suit your car. Experiment with holding the throttle at different rpm and work out where you're quickest to 60ft.

Point noted, I probably should have been more direct and stated that this is not suited to all applications. The vehicle I am talking about is well over-tyred, is light, and isn't set-up to bounce off a rpm limiter on launch. Bringing revs up to a certain level does not bring on boost as well as a number of free (over)revs and then a launch with this vehicle. All best 60ft times have been recorded this way. A 1.47sec 60ft time is not too shabby for a street car

Most normal skylines would be better suited to find a rpm level that best suits there car, then launch.

Fixxxer

[Giffo]

hey mate,

if you having trouble with 60ft times, soften up the suspension if you can, lower your pressure to about 28psi, and launch (riding your handbrake if your not scared to) this will decrese the chance of crappy tyres wheel spinning!

im my 32gtst year ago, my best was 14.1 with front mount, pod, and cat back exhaust with 14psi.

then i started to launch harder and ride the clutch a little, got 13.9. then my old man has been around it for years, now builds drag cars, which i raced when i was yonuger, but he advised that maybe my tyres are shitty, and to use the handbrake... i tried it and it worked, went 3 separate time in my gtst, each time got quicker! 14.1, then 13.9, then after hard launches and handbrake riding, i got it down to 13.4 @ 98mph, 60ft - 2.003

my gtr now has run best of 11.7, but after this build it should be closer to high tens at 130mph or there abouts!

goodluck, and if you want any help or me to come and watch you launch etc, let me know! cheers, Garth

[BU5TER]

more power also works

[Angus Smart]

more power also works

MOARRRRRRRR!!

Edited April 17, 2007 by Angus Smart