Want to run 9.90

Lenny5160 · 02-06-2019, 01:23 AM

Quote:

I just purchased the Pro Cube with 3 timers and ZForce from K&R so I'll let the box shift it on time.

Seems less than ideal, if I'm understanding it correctly. If you want the shifts to happen down track at wide open throttle, the time setting for your desired RPM will change every time you change your throttle stop time. You'd be better off using RPM as the shift trigger.

jlundy · 02-06-2019, 10:46 AM

Quote:

Originally Posted by Lenny5160

Seems less than ideal, if I'm understanding it correctly. If you want the shifts to happen down track at wide open throttle, the time setting for your desired RPM will change every time you change your throttle stop time. You'd be better off using RPM as the shift trigger.

As I mentioned in my first post, it's painfully obvious that I have no clue what I'm doing. That really is the main reason I joined this forum, to read and ask questions.

I guess I need to shift into 2nd on the stop then coming off the stop say 7000 rpm = time? shift into 3rd for the remainder of the run. Thought time was more consistent than RPM?

I thank you Lenny for taking the time to help this racer whom thought he'd have a go at electronics racing.

Hacksaw · 02-06-2019, 11:22 AM

What about getting it to shift to high gear when your on the stop? Wouldn't that be the most consistent? Thinking you would need a little down track speed but your really fooling the car to think it has a PG trans.

Lenny5160 · 02-06-2019, 12:37 PM

How fast does the car run wide open? That will influence the options you have. As Hacksaw mentioned, you can go all the way to High gear while on the stop, but you probably want to be a full second quicker than the index (say a 8.90 or quicker car when trying to run 9.90) to pull that off. I get the feeling that your car isn't that quick.

I've never run a 3-speed, but here's what I think I would do in your situation. I'd launch the car hard, then put it on the throttle stop. Have your shifter hooked to a timer which would put the car in 2nd gear shortly after the throttle stop turns on. When the car goes wide open again, I'd either have some way to put the car in 3rd based on RPM or just shift it by hand at the desired RPM.

jlundy · 02-06-2019, 12:45 PM

Quote:

Originally Posted by Lenny5160

How fast does the car run wide open? That will influence the options you have. As Hacksaw mentioned, you can go all the way to High gear while on the stop, but you probably want to be a full second quicker than the index (say a 8.90 or quicker car when trying to run 9.90) to pull that off. I get the feeling that your car isn't that quick.

I've never run a 3-speed, but here's what I think I would do in your situation. I'd launch the car hard, then put it on the throttle stop. Have your shifter hooked to a timer which would put the car in 2nd gear shortly after the throttle stop turns on. When the car goes wide open again, I'd either have some way to put the car in 3rd based on RPM or just shift it by hand at the desired RPM.

To be honest I have no clue what it runs...........I run at altitude 4000ft. This is an all new combo 445ci SBF, C4 trans, 486 gears. 2260# with me in it.

Just fired the motor first time last Sunday while everyone was watching super bowl.

pmrphil · 02-06-2019, 02:09 PM

Quote:

Originally Posted by jlundy

To be honest I have no clue what it runs...........I run at altitude 4000ft. This is an all new combo 445ci SBF, C4 trans, 486 gears. 2260# with me in it.

Just fired the motor first time last Sunday while everyone was watching super bowl.

Have you done the math regarding rear gear and tire size? As far as finish line RPM goes?

jlundy · 02-06-2019, 03:03 PM

Quote:

Originally Posted by pmrphil

Have you done the math regarding rear gear and tire size? As far as finish line RPM goes?

Yes, I have and finish line rpm would be about 7600.

drgrcr1156 · 02-06-2019, 01:25 PM

I've never run a 3-speed, but here's what I think I would do in your situation. I'd launch the car hard, then put it on the throttle stop. Have your shifter hooked to a timer which would put the car in 2nd gear shortly after the throttle stop turns on. When the car goes wide open again, I'd either have some way to put the car in 3rd based on RPM or just shift it by hand at the desired RPM.[/QUOTE]

I run a 3 speed TH400 in 9.90 and this is how I have my shifts set.

jlundy · 02-06-2019, 12:39 PM

Quote:

Originally Posted by Hacksaw

What about getting it to shift to high gear when your on the stop? Wouldn't that be the most consistent? Thinking you would need a little down track speed but your really fooling the car to think it has a PG trans.

That could work. 1, 2 shift........On stop, come off in high gear. What kind of shock to the converter would that be if any?

Hacksaw · 02-06-2019, 03:13 PM

Quote:

Originally Posted by jlundy

That could work. 1, 2 shift........On stop, come off in high gear. What kind of shock to the converter would that be if any?

I think as long as you have some decent rpm and wheel speed on the stop the converter can handle it and recover quickly. Lots of PG racers do this now. Check with a doughnut maker and get there advice.

02-06-2019, 11:22 AM	#3
Hacksaw Senior Member Join Date: Sep 2016 Posts: 881 Likes: 206 Liked 308 Times in 173 Posts	Re: Want to run 9.90 What about getting it to shift to high gear when your on the stop? Wouldn't that be the most consistent? Thinking you would need a little down track speed but your really fooling the car to think it has a PG trans.

02-06-2019, 12:37 PM	#4
Lenny5160 Senior Member Join Date: Nov 2015 Location: Inver Grove Heights, MN Posts: 898 Likes: 604 Liked 431 Times in 224 Posts	Re: Want to run 9.90 How fast does the car run wide open? That will influence the options you have. As Hacksaw mentioned, you can go all the way to High gear while on the stop, but you probably want to be a full second quicker than the index (say a 8.90 or quicker car when trying to run 9.90) to pull that off. I get the feeling that your car isn't that quick. I've never run a 3-speed, but here's what I think I would do in your situation. I'd launch the car hard, then put it on the throttle stop. Have your shifter hooked to a timer which would put the car in 2nd gear shortly after the throttle stop turns on. When the car goes wide open again, I'd either have some way to put the car in 3rd based on RPM or just shift it by hand at the desired RPM. __________________ S/ST 51 S/C 53

02-06-2019, 01:25 PM	#8
drgrcr1156 Junior Member Join Date: May 2010 Location: Massachusets Posts: 91 Likes: 0 Liked 2 Times in 1 Post	Re: Want to run 9.90 I've never run a 3-speed, but here's what I think I would do in your situation. I'd launch the car hard, then put it on the throttle stop. Have your shifter hooked to a timer which would put the car in 2nd gear shortly after the throttle stop turns on. When the car goes wide open again, I'd either have some way to put the car in 3rd based on RPM or just shift it by hand at the desired RPM.[/QUOTE] I run a 3 speed TH400 in 9.90 and this is how I have my shifts set.