Today was last day of Sunday Grudge Racing at KCIR and BSwithTF came into town so we all decided to go to the track. Weather to say the least was a bit warm. Temps were in the 80 degree range at 1130am when we showed up and got into 85 degree range from 12-4pm when we raced. Charles' G35 indicated 90 degree plus temps on the track. I figured I'd be doing well if I got a 14.7@96mph because my car has always been .3 and 2mph slower between a 50-60 degree day vs one that's 80 plus.

Conditions:
85 degrees
30% humidity
30.0 baro
Sunny
10-15 wind

Prep:
15s in the front, all season, 26 psi
1/3 tank of gas
no spare/jack
suspension set to full stiffness

My first run was a bit interesting. I pulled a 14.671@92.74 with a 2.24 60'. I bogged horribly because the track was like glue. My trap speed was a bit disturbing, but I would guess the trap box might have been off because when I was going thru the last set of timers I was at 6600+rpms which means I was well above 95mph (it averages your last 60'.

My second ran was very disturbing. I increased my launch rpm to 4500rpms and let her rip. Unfortunately I think my clutch started to slip. I hit 2nd and I swear it was slipping again because it sure didn't feel like I was spinning. Maybe I had a peg-leg launch and that's what it feels like I ran a 15.0@95.07 with a 2.41 60'.

I let my car cool off for well over an hour, got the manifold to just "hot" and not "inferno" and then decided to make one last pass to confirm if my clutch was on it's way out. I got into the same lane, revved up 4000rpms and launched. 1st gear felt pretty good, I banged 2nd and felt what I thought was a momentary slip, and then it was fine. Banged 3rd and away I went. The run felt pretty decent. I got my timeslip and my jaw hit the floor:

60' 2.217
1/8 9.327
MPH 75.99
1/4 14.451
MPH 96.95mph (<---going thru the trap box area at an indicated 6600rpms+)

You know what my prior best was? 14.451@99.5mph with a 2.316 60' in 50 degree weather Just goes to show you how important a strong 60' is. You can see how the heat sucked out about 2mph once again. My RPM switch worked fine.

As for my clutch, I can't tell if it was a fluke, hot weather, sticky track, or combo of everything. When I left, I tried my hardest to get it to slip. I banged 2nd and it barked, banged 3rd and it was solid, went up a hill in 4th at 2000rpms and it didn't slip, etc , etc. I can't blame my clutch for dying (if it is) because it's the original, has a 120+ passes on it, and 95K miles.

I'm very certain I could hit a 2.1X 60' with the way the newly resurfaced track is now hooking. I definately going to go to the track the next time we get a 50-60 Wednesday night which should be soon. Hopefully the cool weather will keep my clutch happy.

BTW, a sweet red 350Z 6 speed showed up. He was sitting on some sweet deep dish polished 5 spokes (maybe 19s). He pulled off a 14.46@98mph.



Dave

 

Nice! was the 350 stock besides the rims?

 

 

I think he was stock because his car was pretty quiet.


Dave

 

Do you launch at 4000-4500 rpm when you street race?

 

I really don't street race. In the past two years, I've gotten into two streets races, both of which happened over the past two weeks. One was a 4.6 GT and the other was a L98 Vette. I couldn't resist because I just had to see how the JWT ECU was performing

For launching on the street, I'm running my 17" rims with W-rated tires and yes, I can launch at 4000rpms+ because they are significantly stickier than my 15s on the street. With 15s, I can't go WOT in 1st at all or the tires roast. Coming back from the track today, I constantly found my 15s spinning horribly when I tried to get on it in 1st or making a turn onto a road in 1st. With my 17s, this is never an issue. I can barely chirp my 17s in 2nd whereas my 15s bark very loudly and spin. When it's cold, things get much worse for the 15s.


Dave

 

Nice recap of today at the track Dave. It was perfect weather here today for just about everything but you guys were out doing. Looking forward to seeing this machine of yours soon. You planning on the 19th thing?

 

Wow Dave, I have never seen you post 60' times like that. Is that one of your better 60's in the Maxima? Just think if you could have pulled that 60' last time you were at the track, it would have been 14.3xx for sure.

 

Great run dave!


Now if you only could have gotten that 2.2 60' in the 50 degree weather you would have had a new PB


Maybe next time.

 

I had the same thing happen to me once. I _though_ I was doing a burn out, only I saw no smoke, heard no tires spinning, and smelled clutch! Turned out I was just burning the clutch for about 15 seconds (confirmed by my friend watching). I went ahead and babied it for that pass. Let the car cool for a while, and it was fine ever since.

To this day I've only gotten it to slip one other time, and that was since the SC install.

Good time!

 

What's REALLY weird is I didn't smell the clutch at all. I even popped the hood and tried to smell all over the engine bay for clutch and there was nothing. I burnt the clutch before on accident and it smelled nasty. This time around and didn't smell anything. It was really weird. It's good to know you've experienced the same thing yet you're still using the same clutch with little problems. I know a lot of the LS1 F-Body guys have constant problems with their clutches slipping badly on hot days and then everything is fine. I hope that's the case for me.


Dave

 

Thanks. The next Wednesday night where the temps are 60 or below, I'm going to the track. It's NEVER busy on Wednesday nights so I should get a bunch of runs in. I'm hoping for a 14.2.


Dave

 

Wow, I usly hold the RPMS at 2 grand, and then let go of the clutch really fast, and then give a little gas up to 3 grand and then try to hold it there till i get traction then floor it...

When you launch at 4000 do u just let the clutch go really fast and just hold it there threw the wheel spin, and then when you catch floor it?

 

For most Maximas and most tracks, launching at 2000rpms when your dumping the clutch usually results in spin and then a slight bog. I use to launch like this a couple years ago and my 60 foots were constantly in the upper 2.3s and sometimes 2.4s. I thought to myself that there was no way to launch this thing at all. I then realized that actually increasing my launch rpms and NOT dumping the improved things a lot.

I usually rev up to 3500-4500rpms (depending on traction at the track) and on the last amber I let up on the clutch just enough that the car starts to roll. Once the car is moving, a quickly lift up on the clutch as I'm feeding the gas. My goal is to always stay above 3500rpms coming off the line whether I'm hooking up or spinning a little. I've noticed that when the rpms fall below 3000rpms, the VQ gets bogged down badly even after the 60' and it will kill your times. Sometimes I have to modulate the gas in 1st to keep from spinning way too much. Usually my car will always bite down at 4500-5000rpms and then I can go full WOT. I know it sounds like a lot, but it all happens very quickly. I really don't slip the clutch all that much and I do not release it terribly fast. Dumping the clutch can have some damaging affects if the car hooks up hard (ie broken motor mounts, CV axles, gear, differential).


Dave

 

alright i'll try it... but even tho i launch at 2 grand your right the car can bog. But i dont let it, like i said i let go of the clutch fast, so yeah its spinning at 2 grand, but as i do, u slowly give it gas, so instead of the RPMs droping its slowly goes up to 2500-3000, and then i just anticipate when its about to catch and i floor it

 

Dave, I know this is a little ot, but im dying to know how you squared up against the ls1 and gt in the street race. I wouldnt be suprised if you pulled on the gt? haha What happened?

 

*edited for Monday*

Dave

 

Hey when you told me a couple post back, that you let go of the clutch but not fast....so you stay above 3500...and get the car moving, well does that mean your riding your clutch?

 

I rev up to around 4000rpms (usually) and I lift up on the clutch a little and get the car rolling (we're talking 1-2mph). Obviously when the car is rolling it means the engine are engaged so the rpms fall a bit. When I say I'm trying to stay above 3500rpms, it means I'm feeding the gas as the clutch is coming up. Pretty much my goal is to come off the line at 3500rpms or higher. It's hard to gauge, but I'd guess I'm off the clutch completely in the 1st 20-30 feet or ~1 second give or take a few tenths.


Dave

 

nice run

 

nice run - how much are they supposed to run stock?

 

nobody in here believes in the low rpm launch.

 

I do.

 

My car must be different because when I use to launch at 2000rpms with the same techinque, I would spin then bog. Next time I go out, I'll give a 2000-2400rpm launch a try since my track is hooking so hard now. Maybe it will work and possibly save my clutch.


Dave

 

Ahem...i am a firm believer of low rpm launch on street tires. i launch at 1700 rpms tops.

--Paul

 

How is this done?

 

 

How is a low launch done at 1700??????

I just tryed it, and evey time the car bogs... I hold it there, relase the clutch really fast and floor it, then it bogs and goes...then i try holding the clutch a little bit below ingaging point, and i slowly let it out and she rols a little and then starts to go , but i get slight wheel spin all threw 1st on my 17s

 

i stage the car at 1,500 or so and quickly let off the clutch at the same time applying gas. it should be done to the point that you get a few chirps off the line, but no serious bog. if you're getting bog that means you're letting off the clutch too early without mixing enough throttle.

 

Yeah after the car boged and i went she riped thew 1st like a bad out of hell...like i siad i did get some weel spin all threw first but it wasent massive...i'll work on it..thanks

 

yea, once you get it it comes so easily. it's so similar to a regular launch that you'll be able to do it in your sleep.

 

Good stuff dave. You know how touchy our clutches can be, so I really wouldn't be worried.

In the fairly rare event of me launching, I am a firm believer in the lower-rpm launch + a quick slip through the release point (quick chirp off the line, no bog if done right), not an aggressive drop (which would either bog you to shame or shake your front end loose with wheelhop). I can't even imagine any kind of launching technique at 4000rpms in my max - esp in warmer weather, the clutch rumbles (t/o bearing?) and seems to get mushier as I apply gas before releasing at all, plus I'd think my 15" BFGs would just go spin-crazy...but that's just my clutch and tires.

 

We launch almost the exact same way. (I don't stage quit as high, but blip the throttle slightly on the first yellow.) Looks like I just need to drop my tire pressure some on my Sport A2's to get my 60fts in the 2.1's

 

yup, i drop my A2's down to 15 psi. i guess it's a trend here at atco. you got civics and mustangs alike all dropping tire pressures. what altitude are you running at?

 

500ft at Steele AL.... I run sometimes at (not sure about altitude) Bowling Green KY as well, but track prep there sucks!!!

Last time at Steele I ran at 26.5 psi.

 

I dont know about you dudes with the low RPM launches. I dont think any of you have aftermarket clutches. I think I have tried launching like VQdriver with my clutch and I am pretty sure there is not getting out of the bog. I plan on doing a lot of test and tune this summer and hopefully Rudy will be there to give me some pointers. A 2.0x 60' on street tires is rediculous man.

BTW what is the level of the track Dave is runnin at?

 

I will have my clutch and flywheel before my next track outing. So I will let you know if I can continue to do my low rpm luanches...

Also, I think Dave's track is around 1200-1500ft??

 

My track sits somewhere between 1100-1200 feet. Not enough to make a huge difference, but enough to suck out a little ET/MPH.


Dave