1fastWS6

iTrader: (3)

Here's my dyno graph. I'm shifting at 6600-6700 now. Wondering if I should be shifting higher or maybe lower due to the torque curve. Do you think it would help to shift 3rd or 4th at a higher rpm?

What about ideal launch RPM? The 2 step is at 6000 now. Track prep usually isn't ideal, but it's decent, and it spins a couple rev's max off the line.

Thanks,
Craig

gator's 99TA

iTrader: (2)

your motor pulls hard all the way to redline. i would ideally shift it as high as i could to take advantage of the power and to stay away from low rpm the next gear change. 6700 rpms is all i would stay at if the bottom end is stock.

also if you are racing at KCIR, they prep the track pretty well. with your tq, moser, and clutch, you should be pulling 1.59 or quicker. i know i have at that track (used to live near there). 26" et streets and manual trannys have never gone well together for me or my friends that race up there. think about an et drag.

soliari

I'm not sure I would go any higher than 6700 with a stock bottom end either ... otherwise shift at 6800 or 6900 ... just like gator suggested.

1fastWS6

iTrader: (3)

Thanks for the responses.

I wish I was racing at KCIR, that's a decent track. The track I usually go to is basically a strip of pavement out in the middle of a field. My best 60' so far is before the new cam and it was a 1.64 on a 5500 dump. My shiftlight is set at 6600 so I probably actually shift at 6700 (I'm slow LOL).

I'd like to try some taller ET Drags, something that has more sidewall. I wish they made a 27" X 10.5". I think a 28" would slow me down. And, the 26 x 16's just aren't very consistent.

Navy David SS

iTrader: (13)

1fastWS6. I had the same problem. I went with the ET Drag 28x9. They are only 27.3" with a roll-out of 88. The are bigger than the 26's but not as big as say 28x10.

At our track the 28x9 work great. Also the 28x9 are the soft compound, where as the 28x10 are the med to hard compount.

David

1fastWS6

iTrader: (3)

Hmmmm, might have to look at those. Thanks David.

Colonel

The bad thing about big cams with stock bottom ends is that you can't spin 'em up as high as they need to be spun. You have a cam that wouldn't mind being shifted at 7200 and it BEGS to be shifted at least at 7000.

1fastWS6

iTrader: (3)

I agree with your statement about big cams and stock bottom ends, but based on the way the tq drops off with this cam I didn't think shifting past 6800 would do me any good.

I guess the basis for asking my original question is to figure out how you determine optimum shift points. Doesn't it somewhat relate to the trans. ratio's also to keep the rpm's from dropping below peak tq on each shift? It has to do with more than just the peak of the hp curve correct?

And, how much do you think I'm giving up in ET by not shifting at 7000?

Thanks for the help guys....

JS

iTrader: (4)

Steven is correct,My buddy told me to shift my car (6100 peak carrying to 6400) at 6500 on the 1 to 2 shift but shift it at 6400 on the 2 to 3 shift due to the closer gearing on 2 to 3?

But the very best way is to race and play with the shift pints.
I'm gonna set them 6500/6400 and be done with it...

Your car really pulls right to 6500 but falls off quickly..
I'd shift yours around 6700 on the 1 to 2 and 6600 on the 2 to 3.

Colonel

Quit thinking "TQ". You gotta look where your HP ends up after a given shift...and yes, that has to do with your tranny ratios. You must also consider that the quicker your engine spins up, the more HP it robs from itself in the process of doing so. In some cases this can make the optimum shift point lower on the 1-2 shift than on the 2-3 shift, for example. In other cases, due to wider 1-2 ratio drops it can have you shifting at the same or higher RPM on the 1-2 and 2-3 shifts.

As you can imagine, optimum shift points for a high stalled auto with a shift extension of 5900 on the 1-2 will be different than with an M6 with it's HUGE RPM drop between 1-2.

Joel's right, experiment, experiment, experiment!

JS

iTrader: (4)

This is true,U really cant say this is where it SHOULD be and thats it.
Go out and race the car and find out what it likes by shifting higher on the 1/2 or lower and the same for the 2/3 until ET falls off.

I'm sticking w/my 6500/6400 theory and leaving well enough alone

NJSPDER

iTrader: (2)

i always apply the rule of thumb that you shift based on where you will land on the torque curve, taht seems to be how i got my best et's in my cars at least. if you can drop the engine rpm back to around 4750-5000rpm you will be hitting peak torque after the shift, that will help the car carry better between gears.
taht would put your shifts in teh 6800-7000 range(right around where gator suggested). i would suggest leaving at a slightly lower rpm, go down to say 5700, and try hitting the shifts at 7000.

good luck

later
tim

Colonel

Where the peak TQ is has ZERO to do with where I shift any car. Baseing it on peak TQ RPM is not logical (no offense intended to Tim.) You want to put down as much HP to the ground over the course of 1320 ft as you can. That's the bottom line.

NJSPDER

iTrader: (2)

that is always what i use to pick gears so that i use the whoel hp curve up as i get to the traps.
i know what you are saying. i have seen both schools of thought work equally.
shifting for torque usually results in less mph for the same et, dunno why.
i have always managed to make a tenth or so that way. when i shifted my cars for hp i always gained a bunch of trap speed and didn't seem to get any et out of it though.

later
tim