DaddySS

Went to the track yesterday (SLP Day) for the first time since doing bolt ons and a lot of other work.

I was hoping to not only beat my previous (stock) time but get into the low 13s or maybe even high 12s.

Well, I didn't even beat my stock time! I was hoping you all could give me some insight on how to launch with the M6 and what else I am doing wrong.

I am currently making 365 rwhp and 362 tq with the mods in my sig.
Stock I was at 308 rwhp and 314 Tq.

Stock:

r/t 1.064
60 2.273
330 5.994
1/8 9.036
mph 80.90
1000 11.638
1/4 13.832
mph 102.91

now:

r/t .458
60 2.339
330 6.063
1/8 9.128
mph 79.25
1000 11.718
1/4 13.938
mph 102.19

To launch, I brought it up to about 2000 and dumped the clutch and stepped on the gas - spun the tires and had to let off a bit to get traction. I didn't power shift because I was a little rusty and didn't want to break anything but the shifting was quick and precise.

I did a quick burn out to clean off the tires before the run. Rears are BFG KDWs - 285 40 17, and I did not lower the inflation.

So is this a matter of launcing at lower RPM, feather the clutch more, easing into the gas rather than flooring it? I would have thought that even with a bad launch, the extra power would have at least let me beat the old, stock time?

Steve Burger

iTrader: (33)

Traction is the key. Look at your 60' times. They went up not down. With more power it will be harder to launch on street tires. At your power level I was running 12.8s on Nittos and 12.4s on ET streets.

Looks like you are doing a lot of spinning. Even the 330' and 1/8 times are higher. Hook it up and you will see better numbers.

T6Rocket

Also, something power wise isn't quite right. You gained 57 HP, but no gain in 1/8 or 1/4 MPH. Should have gained 3-5 MPH in the 1/4.

Al

MattG

You will never get times you will be happy with until you can get those 60s consistantly in the 1.95 - 2.00 range on street tires. The trick is to come off with enough RPM not to bog the car when it hooks, but not enough that you will just burn the tires all hte way through first gear. It requires some tricky throttle modulation. Give it just enough throttle so the engine doesnt bog and the tires spin just slightly. When you feel it start to hook, slowly press your foot down on the gas. Launching a 6speed car with some power on street tires is definitely not easy to do. Just keep practicing and you will get it. Just remember not to murder it off the line, and don't let it bog. You have to find the happy medium between those two!

ONGRNGO

Go out and buy a pair of nittos bring the PSI down to 15psi cold do a long burnout, like 8-10 sec, launch at 2500 to 3000 RPM and you should have no problem cutting a 1.9 or better 60ft that way, thats what I do and have cut a few low 1.8 60fts on my nittos. Street tires and more power don't go good together, thats my opinion.

Dan

jimmyblue

iTrader: (11)

Aside from the traction problem, do you know whether
you are shifting so as to get the benefit of the higher
power/TQ? How peaky is that dyno result, and are you
staying on top of it (the power/TQ curve)? You may
have to modify your shifting habits as you modify the
powerband.

DaddySS

Thanks for the feedback.

Steve, ONGRNGO - I was hoping not to get DRs simply because I only run a few times a year at the track - I mainly want to make the most use, and most fun with the power I have.

T6rocket - Yes, I thought the same thing. I just don't get why is wasn't faster?

MattG - I'll give those a try. I really thought it was grabbing pretty well but with the helmet, the noise from the other lane, my own inexperience and nervousness, etc. it's hard to tell. Where do you generally get to practice?

Jimmyblue - The torque curve is real flat - 325@2500,350@3100,362@5000. HP maxes @5700 but stays strong to 6200 and then drops off. I was shifting at 5500 to be a little on the conservative side and figuring that it would be at 5700 or so by the time I actually shifted.

DietCoke

iTrader: (18)

You need to be shifting at 6500 rpm is your biggest problem. Your shifting before you even make peak power, thats a waste.

Steve Burger

iTrader: (33)

Diet Coke is right. 5500 sift point is low for a stock cam. You are leaving a lot of power on the table at that shift point. I shift at 6800.

DaddySS

Thanks for the feedback so far gang.

So I should adjust my launch RPM a bit lower - balance between bogging and spinning, and shift about 500 to 1000 RPM higher.

How much difference will power shifting versus granny shifting make?

Assuming standard weight for a vert - where should my time be with the power I'm making?

DietCoke

iTrader: (18)

power shifting is worth .3 if you can shift the hell out of it. Shift at at LEAST 6500 rpm.

METALBEAST

iTrader: (1)

Your 60' time doesn't concern me as much as your 1/8 and 1/4 mile trap speeds. I had a similar problem when I first put my mods on my vette. It ended up being a bad tune.

MattG

Power shifting is good if you are real good at it, otherwise it can easily slow you down. I don't believe it is worth 0.3 seconds over a quick smooth consistant shift involving a quick flick of the clutch pedal. Power shifting on street tires sometimes just shocks them too bad in 2nd and you end up spinning harder in 2nd than you would have with a normal shift.

Practice your launch on the street with the same tires you are going to run at the track.

I do agree with the shifting at 6500rpm!

DaddySS

DietCoke: Two things; I am very concerned about shifting at 6500, first, the max power band holds steady between 550 and 6500 then drops, so shouldn't I be OK shifting between 6 and 6500? Second, when I ran stock I shifted between 6 and 6500 so I would think I would least be OK shifting there with the mods.

Metalbeast: I know what you mean, that concerns me too but I had it re-tuned about two months ago after I replaced the Catco cats with Carsounds and added the LS6 intake and picked up about 10 HP and Tq across the band. It feels very strong.

One thing that bothers me - on my first run I launched the same, spun a bit, and missed third and hit fifth and ran 14.1. The second run, the launch was the same, but all shifting was quick and precise and I only picked up .2?

silverbeast

iTrader: (16)

you need to practice!!! and get some tires.

DietCoke

iTrader: (18)

Sure, your OK shifting there, but your going to be SLOW like you are now. You shift at 6800 rpms because your making more power from 6400-6800 then you would be if you shifted at 6400, plus your shifting more into your powerband. Its all about powerband. If you shift at your peak, you should have gotten a smaller cam. You can't put up good times with a cam that peaks high unless your willing to turn the rpms to go fast, and thats all there is to it.

70 TA

Like everyone else said launching is the key to better times.

To learn how to launch I went out to a deserted side road and learned how to slip the clutch while keeping the RPM's up.

I rev to about 2500 or so and let the clutch out enough so it starts to grab and then floor the gas and slip the clutch so that I get very little or no wheel spin with the revs around 5000. Once I'm moving and I know the tires wont spin I let go the clutch fully. Sometimes I get a very slight bog but by this time I have good forward momentum and even though the revs drop a few hundred RPM the car seems to lurch forward so it doesn't slow my time.

I took me a couple times to get it sort of right but after about 10 times it should be second nature. Just dont do it too many times in a row without letting the clutch cool off.

Your shift point is another story, I shift my stock car at 6000. You powerband is certainly higher than stock with that cam and mods. You shouldn't be worried about revving it higher the bottom end can handle it. If in doubt about your top end and you didn't already you should upgrade your valve spings, pushrods and retainers which are the weak point of a stock LS1.

The time in my sig were for my stock Lid only SS on street tires.