Top Fuel

iTrader: (8)

how are shift points programmed with LS1 Edit?

by mph or rpm?


thanks,
Steve

Top Fuel

iTrader: (8)

thanks ONYX. <img src="gr_stretch.gif" border="0">

Won't my shift points be thrown off at the track with bigger tires, since my pcm will be programmed to my street tire size? <img src="images/icons/confused.gif" border="0">

Steve

Pro Stock John

iTrader: (34)

Top, I wonder the same thing.

I am going to change my shift points with Brian from BV Performance in the next couple of weeks.

I plan to run taller tires at some point and I would think that 28x10x15 Hoosier slicks would throw off the MPH thang right?

That being the case, if I want both of my shift points at 6600, what mph would that be at with 4.10's?

Top Fuel

iTrader: (8)

with 4.10's:

a 26" tire hits 6600rpms at 41mph on the 1-2 and 77mph on the 2-3.

a 28" tire hits 6600rpms at 44mph on the 1-2 and 83mph on the 2-3.

So if you use 41mph as your 1-2 shift point, but use a 28" tire, the car will short shift at 6100rpms.

If you use 44mph as your 1-2 shift for 28" tires, but decide to go back to 26" tires you will shift at 7200 rpm. <img src="gr_eek2.gif" border="0">

I think thats right? <img src="images/icons/confused.gif" border="0">

later,
Steve

Terry Burger

iTrader: (4)

2001 cars shift by RPM, maybe you can change pre 2001 cars to do the same?

Ryan K

iTrader: (11)

Well guys it does shift off of MPH. BUT remember it calulates MPH from the Drive shaft speed. So as far as the computer is concerned, no matter what size tire you have the computer is going to think you are actually the same speed at a given rpm. The computers only method of seeing speed is at the Driveshaft. Your speedo will be wrong but that doesn't matter. The computer should shift at the same rpm give or take differences in slip speed of the TC.

Ryan "hope that made sence" K.

<img src="graemlins/fluffy.gif" border="0" alt="[Fluffy]" />

Ira

[quote]Originally posted by Ryan Karasek:
<strong>Well guys it does shift off of MPH. BUT remember it calulates MPH from the Drive shaft speed.</strong><hr></blockquote>

Yea Ryan. You understand correctly. You could also say, it shifts off indicated speed, not actual speed as the car has no real clue how fast it's going, only how fast the driveshaft is turning.

Ira

ONYXSS

mph

Top Fuel

iTrader: (8)

Ahhh <img src="gr_stretch.gif" border="0"> thanks Ryan and Ira, that cleared things up. But now to the next question...

How do you figure out the indicated mph that would equate to 6600 rpms? Or should I just tell my tuner that want to shift at 6600rpms and let him figure it out. <img src="gr_grin.gif" border="0">

thanks,
Steve

ToplessTexan

[quote]Originally posted by Ira:
<strong>

Yea Ryan. You understand correctly. You could also say, it shifts off indicated speed, not actual speed as the car has no real clue how fast it's going, only how fast the driveshaft is turning.

Ira</strong><hr></blockquote>

Just as a point of interest, C5s works a little differently. The VSS pickup is on the ring gear and what the PCM sees is really axle rotation rate not driveshaft rotation rate. Where is the F-body VSS signal supplied?

Ryan K

iTrader: (11)

It reads it at the output of the transmission, on the tail shaft.

Ryan <img src="graemlins/burnout.gif" border="0" alt="[Burnout]" />

Chris Spiess

[quote]Originally posted by Top Fuel:
<strong>How do you figure out the indicated mph that would equate to 6600 rpms?</strong><hr></blockquote>

There is a setting for tire diameter somewhere I think. The formula would be
Driveshat Speed/finalDrive*tireDiameter(in)*PI/12/5280*60

Or

Driveshat Speed/finalDrive*tireDiameter(in)/336

Where Driveshat Speed = Engine RPM/Trans gear ratio

[ February 15, 2002: Message edited by: spiesscj ]</p>

Ryan K

iTrader: (11)

There is a setting for tire diameter somewhere I think. The formula would be
Driveshat Speed/finalDrive*tireDiameter(in)*PI/12/5280*60

But, remember the Torque converter has slip, so that equation doesn't account for TCC slip speed. Every car is going to be different so, its more of a trial and error setting.

Ryan <img src="graemlins/fluffy.gif" border="0" alt="[Fluffy]" />

Pro Stock John

iTrader: (34)

Verter slippage affects it how? up or down?

What would I plug into LS1 Edit to have 6600/6600 shift points with a 4.10 gear out back and 26" tall tires.

Ryan K

iTrader: (11)

PSJ, The engine will be going faster than you would expect. So first start off low and then work your way up to where you want it. Make several test runs at the track and see what RPM is on the shift. YOU MUST HAVE TRACTION because spinning tires lowers the amount of TCC slip you get.

I for my first try, I would go for:
1-2 @ 35 MPH
2-3 @ 66-67 MPH
3-4 @ 110 MPH then at the track leave it in (D)

Thats where I would start.

Ryan K <img src="graemlins/gr_cheers.gif" border="0" alt="[cheers]" />

Pro Stock John

iTrader: (34)

I remember doing 40/80/120 with Ed Wright a while back.

Mr Cowl Hood

But, remember the Torque converter has slip, so that equation doesn't account for TCC slip speed. Every car is going to be different so, its more of a trial and error setting.

Ryan <img src="graemlins/fluffy.gif" border="0" alt="[Fluffy]" /> [/QB][/QUOTE]

True true. You can use the standard shift Pt Vs RPM tables to get pretty close though. It's actually fun to see cars make more power and creat higher stalls so that you have to go back into the program and adjust shift points for it!!!
<img src="graemlins/burnout.gif" border="0" alt="[Burnout]" />

[ February 15, 2002: Message edited by: Mr Cowl Hood ]</p>