1/4 mile driving tips, all turbo drivers please pitch in!

[Guest bastaad525]

Alright... as mentioned in another thread, I'm hoping to FINALLY take my turbo 240 down to the 1/4 mile track, hopefully this Friday. This will be my first time to the track with a turbo car, and only my second time to the track EVER. So... I'm not expecting to break any records

 

Truth is, even after driving this car for 2 years, I still feel like I'm a crappy driver in it, especially when it comes to launching the thing 'efficiently'.

 

My short time as a G-tech Pro owner (one of those 'performance meters' that measures your 1/4 mile time, trap speed, 60' time etc.) seemed to confirm this. I was 'only' able to achieve a best time of 13.4, but the trap speeds consistently averaged about 108mph (which seems to match up better given the known weight and wheel hp of the car), indicative that I could do better. Worse still, were my horrible 60' times, which averaged 2.7 to 3 seconds.... !!!!

 

So, I was hoping you guys could give me a few pointers. I TRY to launch the car by revving the motor to about 3000rpm and slipping the clutch to get the car moving and to build boost, but I think I'm slipping it for too long.. I dunno.

 

Anyways is this the best way to do it or should I just hold revs and drop the clutch?

 

I'm hoping to get everyone who's run the 1/4 in a turbocharged car to pitch in here with their experience as to which launch method produced the best 60' times. Even on cheap tires I should be able to pull better than a 3 second 60'!!!!

 

I don't know how many runs I'm going to get in, but I know it's a popular track and this will be on a friday night so I am guessing it won't be too many, so I'm not really going to get a lot of practice... so the more advice you guys can give me the better

[Guest ON3GO]

i can launch a turbo Z pretty good.

on my crappy old tires i got 1.9 and 1.8's all the time.

i always brought mine to around 4000 or so and feather the clutch.. sorta slip it but hold the clutch abit longer the normal.

i do this but maybe you dont want to... i never lift off the gas when i shift.. powershifting is your friend for fast times!

launching really depends on your tires.. so the sticky they are the higher you can launch.

just pratice it each run and you will get it down.

 

mike

[Guest bastaad525]

well... my tires are crap. They weren't that great when they were new, and as of now, they are just about ready to be replaced. They were $25 ea. all season radials, and are only 195's.

 

Again, practice really isn't a luxury for me... I don't think I'll get too many runs in, and I won't be going to the track on a regular basis. Chances are this will be the ONLY time I go until I do some more upgrades (heh... read that as: a really long time).

 

And I'm definately NOT going to powershift... yeah I know it definatley improves times, but at the cost of who-knows-what damage to various drivetrain components... not worth a few tenths for me.

[Corzette]

Automatic....

[Guest bastaad525]

I'd love to run that Maxima 4 speed AT but there's so little info on the swap and as always, I'm very broke

[EZ-E]

What I do, and its prob diff from most. Well anyway here it goes, and it could be the result of my shabby 60' times, but it works for me.

 

Well I pull up at the line, Ill rev to where Im hearing the turbo spool and will kind of feather the gas between 2500 and 3k. When you are there you will get to know when the light is going green.

 

Usually my times in the 60' are between 1.85 and 2.0, and I think that is the light start I give it.

 

In my ZX the best time I had with stock components was a 13.4 at 101.8.

 

With upgrades and the additon of an LSD I was able to lower that time to a 12.9 at 109.5, and the one thing that I did find was that with the larger turbo I didnt have to shift into 5th.

 

That was also with the 3.54 stock rear. It seemed that the car was running out of breath.

 

With the new turbo, TB and injectors, I can finish the track in 4th without worry.

 

I dont know why this is different, now with a 240Z if you can get traction, I dont see why you couldnt get to the low 13's or 13 flat.

[Guest bastaad525]

well, I don't seem to have a problem with traction, even with the massive 300ft lbs of torque to the wheels on crappy 195 width tires and open diff. Which tells me I'm not launching it right. I really have to abuse the clutch to get the tires spinning off the line. I try to slip it just enough to build boost, get the car rolling, not spin the tires, and yet not bog it either.

 

I never hear the turbo spooling if I just rev it in neutral

 

If I fix this boost spiking issue and get my boost back up to 14psi, knowing the weight of my car with me in it (almost exactly 2600lbs) and my estimate of 240ish rwhp (based off of my last dyno run with screwy boost curve which has since been fixed), and IF I could drive the thing PERFECTLY, I would expect a 12.8-13.0. Trap speeds from the Gtech seem to confirm this... according to a Car and Driver test of a bunch of performace meter devices, the Gtech came up pretty accurate. It gave me consistent 106-108mph's.

 

As it stands, with the spike I've got boost back down to like 12.5psi, and knowing I still suck at launching, yeah I'd be surprised to get a mid 13. Most of my Gtech runs were in the 13.7 range with horrible 2.5 second or higher 60' times I did manage ONE 13.4 at 108mph with a 2.3 60' time... but even with the Car and Driver review, I dont' trust the thing enough to say it wasn't just a fluke.

 

You know, I just remembered, there's one other thing I need to pass tech, I think? A battery tie down... Im' just using a heavy duty rubber bungie cord I'm gonna try to get one asap here but if I can't then I guess no track for me this week

[Scottie-GNZ]

You always hear me talk about seat time, so hear is my $.02 for your first trip to the track.

 

For this test session, resist the urge to "race" the car in the other lane. COMPLETELY IGNORE WHO LINES UP AGAINST YOU. For the 1st 2 passes, forget about the lights, reaction time and quick 60' time. Just launch the car best you can and make sure the car will make it down the track w/o problems looking for the best MPH. Not the same as testing in the backroad. Once you know the car is running w/o problems, then start concentrating on the launch. By this time you will have gotten over the nervousness and even disorientation at the starting line. FOCUS. You have to know what the car is/is'nt doing so you can know how to adjust your technique next time up. There is no magic formula for launching a turbo, stick shift Z-car. The only constant is that you cannot just dump the clutch.

 

195 tires on a 300hp car?

[Guest bastaad525]

well not quite 300hp but 300 ft lbs... torque falls off fast so I only end up with 230-240hp to the wheels. Because the car is already rolling at some speed before the turbo hits full blast, I rarely have a problem with traction when taking off from a light on the street.

 

And what can I say, I'm broke and they were cheap. I'm running the stock '81 non turbo ZX wheels, I think the biggest tire they will fit is a 205 or 215 maybe? Upgrading the wheels is not an option now or any time soon.

[Pyro]

I wouldn't even go with old hard tires. Nothing more frustating than no traction off the line when at the drags.

 

Wait until you get new rubber on the rear wheels before you go. Fresh rubber, even if it is cheap rubber, will make a huge difference.

 

In the early evening, the traction on the track is worse than on the street! The starting line doesn't get sticky until a bunch of cars lay down fresh rubber which typically takes until 9 or 10 at night. At least wait until then before running it.

 

Try removing the front sway bar for better weight transfer.

 

Good luck.

[Guest bastaad525]

eh... I dont have money for tires right now anyways

 

well if worse comes to worse and traction does end up sucking and hence my 60' times, at least you guys will be able to look at my E.T., mph and 60' and say "hey if you can get your 60' down to x then you should be able to run an x E.T.", right?

 

I'm even more curious as to what mph I'll run... I want to see just how accurate that Gtech really was, and also see if what few mods and changes I've made since my last dyno have made a difference in the power level tot he wheels.

[Guest ON3GO]

you can fit a 235 tire on your wheels.

the turbo wheels arent any wider, there 15x6.5.. and if they are wider its only by .5 inchs.

if there the same you can fit a 235 on it..

if there only 6inchs wide then a 225 you can do, still think you can squeeze a 235 on it.

have fun and be safe.

 

mike

[Guest bastaad525]

Can anyone else confirm this? Not that I doubt it... I never really bought tires for their size... never really had enough power for it to matter. I just bought whatever would fit that was cheap/on sale. Last time it was 205's, this time 195's. I seem to remember the last time them telling me the largest it could fit was 215's, and 195's were the smallest. The 215's were like 50% more if I remember right though

 

I have the four point N/A ZX rims, I forget what people call them. pics are in the link in my sig... well and duh my avatar but dunno if you can see them well there, I know I can't.

[Guest ON3GO]

you have the iron cross's.

i have 235-60-R15 BFGoodrich Drag Radials on some 280zx Turbo swats wheels..

there 15x6.5...

i think the iron cross's are 15x6.. still a 225 can be put on that for sure... a 235 might be pushing it but hell i would try it.

 

mike

[Guest bastaad525]

'iron crosses' are 14's actually

[Guest ON3GO]

so 14x6.. hmmm damn that sucks..

can still get some sticky rubber for 14inch wheels though.

if it wasnt for the bigger brakes i plan on and run on my Z's i would run 14's and 15's only on a Z.. just looks awesome i think.

 

tire.com is your friend

 

mike

[Pyro]

Well after reading you post a little closer it seems your traction is good. Sorry for getting on the subject of tires.

 

I think you need to find your ideal take off rpm. Before you go to the track find a quiet street with no houses near by. Then do a fairly quick clutch and throttle drop at 3000 rpms and see what happens. If it doesn't spin the tires then go up in 200 rpm increments until it blows the tires away. This will get you a range for a take off rpm. A little to moderate wheel spin is ok and the engine should be on boost quickly if you are going to make a good 60 foot time. Then try delaying the throttle drop by 0.5 second after the clutch drop. Try to come up with a simple technique because at the track, simple is best.

 

If the boost just breaks the tires loose real hard then plan on doing some suspension work, installing a lsd, and getting a set of wheels with slicks just for track day. Otherwise just concentrate on getting a high mph. Yes, getting a good MPH is also an important feature of drag racing, especially in a street car that is not good at running quick et's due to bad traction off the line.

 

Make sure to stay out of the water box at the starting line. But do a little burnout to clean off your tires. Radial tires get there best traction at maximum air pressure, so check your air pressure.

 

I was looking at my old time slips and I also had a hard time running good 60 foots in my turbo car: 2.142, 2.387, 2.306, 2.532, 2.371, 2.515, 2.306. The boost would come on and the tires would just spin! My car would run between 13.6' and 13.7s from 106 to 108mph.

 

My 240 V8 zcar with N20 ran 1.5's 60 footers all day long. And all I had to do was side step the clutch at 5000 rpm and push the gas pedal to the floor. It felt like the front tires were lifting! Slicks, no front sway bar, stiff rear and soft front springs was my only real mods. I'm not the best driver off the line either but if the car has traction and torque it doesn't matter. But I can tell you that 1.5 60 footers feel fantastic! That was most of the fun of the entire drag race. However stopping an old Z going 135mph at the end of a short track wasn't. Hahahaha

[True School 240Z]

You're gonna run it at LACR?

[Guest bastaad525]

Pyro - yeah well... it's not so much that I have good traction, I think it's just that I dont know how to launch right. I think I'm still bogging it enough off the line and that's why the tires don't break. Well I should say TIRE because I only ever spin one. I think the numbers you gave are probably going to be spot on with what I'm going to end up getting... high 13 at like 108mph. Sucks because at 108mph I should technically be able to get a high 12d in a 2300lb car

 

I've actually considered, many times, getting someone else to drive the car for me, someone who knows what they're doing

 

When you say "radial tires get the best grip and maximum pressure" um... what exactly IS maximum pressure? The 'regular' pressure for them is 32-35psi... I've run them as high as 40 before (was toying with pressures to affect handling)... not sure what the 'maximum' is they can actually hold though

 

And you did hit one nail on the head... I'm actually kinda scared about what's going to happen at the END of the run... how well my stock brakes are going to be able to haul me down from ~110mph. I hope there's plenty of space at the end of the track for slowing down :/

 

 

TrueSchool - yeah I think that's LACR, the one in Palmdale. I just always call it Palmdale so I'm not sure. If I go it's going to be me and two other guys with Z's. I still need to locate a battery tie down or I guess I"m out. If you want to go though it would be those other couple guys, always nice to roll in a pack of Z's Then again I haven't heard from the other guy so maybe they aren't going this week either?? I'll call him tommorow.

[gexgexgexgex]

I live only about 20 mins form LACR and i would like to maybe meet you guys there. I will not be bringing my Z because it is still not tuned hopefully in a few weeks. I i have not seen a turbo z at LACR yet. I would just like to know if you are going or not and at about what time.