silverz28camaro

well my 1-2 shift is perfect(6100rpm) but my 2-3 was still off, rev. limit is at 6500 and the shift is at 6500rpm, i still took it to the track and ripped off some good times, but it felt like the motor(which is stock except full bolt ons) seems to shut off past 6300rpm, now i set my shift mph from 74 down to 70 and now it shifts (2-3) at about 6100-6200, seems to more powerful at the beginning of third opposed to the end(past 6200rpm) of second. Question is do you think i can gain more time in the 1/4 mile from this, really trying to get into the 11's with stock internals

does anyone know what a bolt on ls1 dyno numbers are at 6,100/6,200/6,300/6,400 and 6,500rpm?

i would imagine if the power diff from 6200 to 6500 is any more than a 20hp drop then my car may pick up a .1 and 1 mph in the quarter

most guys who run my 1/4 mile trap speed of 111.3 also trap an 1/8 mile time of 88.5 or better mine is 87.8

times are;


2000 auto camaro
13.54 @ 104 2.049 60' stock 2.73

12.94 @ 109 2.002 60' full exhaust, lid, tune, nitto 555r 2.73

12.279 @ 111.06 /1.740 60' /7.840 @ 87.8 mph 1/8 mile; full exhaust, lid, tune, nitto 245/50-16 555r 3.73 moser 12-bolt 2800 fuddle, ls6 intake manifold, slp under drive pully.

if i could still go to the track i would but its closed til march. just need something to look forward to

VinceTrifecta

I have a dyno chart for my 1999 Z28 w/ a CAI on my site (http://www.trifectaperformance.com/dynos.aspx). The motor stopped making power around 5800 or 5900 RPM so I actually adjusted my shift points downward (I believe the stock RPM threshold is 6000 RPM on the car).

But, as you state if you rev it past the power band, you may pick up performance after your shift because the loss of power for going past the peak is more then compensated by the amount of power you'll be at after your shift due to the increased RPM. If you have a dyno sheet from your car, and you can correlate before shift and after shift RPM you can determine, theoretically, what the best shift point is. But, as is the case with anything, you'll need to test your theory, also. ;-)

C_Rules

is there any science to picking where to shift. or is it just mess around with it to see what gives you the fastes times at the track?

silverz28camaro

i see what your saying, run the car, change this or that and run the car again and note gain, BUT the problem is i had my car dyno tunned and when i put in the gears and stall it kinda throw things off put i do believe it is where it need to be at now (6200) i just wanted to see what people here thought my gains would be.

i remember looking at that tack and seeing 6,300...6,400...6,500. it just seemed like it took to long and didn't feel like it was pulling hard.

Now it shifts at 6,200 and at 4,900 in 3rd it feels as if it pulls harder from being in its power band instead of out.

Guess we'll see what kind of times and trap speed i run next spring

WS6T3RROR

There is absolutely a method to picking shift points at WOT. Here is what you do. For best results dyno the car and get a print out of the tq curve the thing makes, for so so results use dynos from similar cars. Now that you know where your tq is which is what accelerates the car, you need to know that the transmission is what defines the rpm drop. So look up the gear ratios in your trans, and rear then convert the rpms to mph, now you have tq vs mph. If you graph every mph available in your rpm range in every gear, i like to use excell. where the lines cross should be your shift mph, but I always convert back to rpms just to make sure i feel safe taking the engine to there. The hard part is getting your trans to actually shift when you want it to but you can tell what its doing if you have a good data logger, it'll take a couple of shots to work out how long the shift is and slip and junk like that, but it should easily put you in the ballpark.

Also, dont believe your butt dyno, calibration may vary .

Edit: Sometimes its also just a better idea to stay in a gear and rev it out at the end of the track, rather than upshift and try to pull another gear. That particular situation is a try it and see, and can be avoided if you have an accurate example of what the car will do mph wise and what your engine does after max power.

C_Rules

you have a copy of that spreadsheet template that you could attach?

WS6T3RROR

Mine was lost when my old laptop died last summer and i havent gotten around to making another one. Its really not too hard, when i get the chance to make another i'll set it up in a form anybody can just plug the numbers from thier ride into (gear, trans tire height etc) and then i'll post it. Unless somebody beats me to it, i'm sure i'm not the only one who does it this way, as i read it on this site somewhere a long time ago.