RPM Shift points after Ported IM and TB - Page 2

KingLT1 · 10-04-2020, 10:29 AM

Agree...I shifted mine at 6500 rpm. Helps the 4-5 quite a bit.

cmitchell17 · 10-04-2020, 01:22 PM

Its a huge PITA to get these things to shift where it needs to, and its still usually extremely inconsistent from shift to shift. I had to just sit there and adjust WOT shift MPH by 1 and flash, then try it, then flash again, and repeat, it takes forever. If you have bad tires and bad traction its going to hit the limiter easily.

I tried to adjust the RPM limiter acceleration rates to not cut fuel as early as it does stock, so in case it spends and the transmission can't shift as fast it won't hit the limiter. If it does get into the limiter it cuts power back severely and ruins the run.

laynlo15 · 10-07-2020, 06:38 AM

I moved all mine up 2 mph and 100 rpms starting in the 2-3 shift. Should get plenty of TNT on Saturday to have time to make adjustments if needed.

6spdhyperblue · 10-07-2020, 10:47 AM

Has anyone made a calculator for the auto gear ratios? rpm x (that gear ratio x rear gear x tire height) to get the exact mph? Am I thinking about that right

We need a wallaceracing with our stuff prepopulated

RobbyBeefcake87 · 10-08-2020, 10:40 AM

Quote:

Originally Posted by laynlo15

35 60 87 114 157MPH all at 6400

Dang that 4 to 5 on the a8 seems a bit steeper than our 3 to 4 on the m6's.

laynlo15 · 10-08-2020, 12:34 PM

My Camaro used to shift into 5th about 1000 ft I would guess and that last 320 feet goes pretty quick and then trapping at 147 to 149 mph.

6spdhyperblue · 10-08-2020, 01:09 PM

Man that’s a mph..crazy

wnta1ss · 10-09-2020, 07:55 AM

Quote:

Originally Posted by 6spdhyperblue

Has anyone made a calculator for the auto gear ratios? rpm x (that gear ratio x rear gear x tire height) to get the exact mph? Am I thinking about that right

We need a wallaceracing with our stuff prepopulated

Gearing is not difficult to calculate. Here's a formula:

sum of drive tire rolling circumference in feet times engine rpm
divided by
sum of gear ratio times differential ratio times 88

Example for an SS with runflats, A8 trans in 4th gear:
Tire circumference I will use 2016 GM spec for SS runflat 7.078'
Engine rpm 6500
Gear ratio 1.69
Differential ratio 2.77

Result is 111.68 mph

Now I will mention that the WOT shift mph programming for the automatics is not the actual mph that it reaches. This parameter needs to be lower to a varying extent, or the rev limiter will kick in and close the throttle, making you lose your momentum. This is why cmitchell17 said the auto tranny is a PITA, because it takes some logging and further tuning cycles before it shifts correctly.

laynlo15 · 10-15-2020, 08:50 AM

Went to track last night and the ported intake/Tb didn't really show any et gains and 1 mph on 2 of the passes. It didn't loose any so that is good. I did make some shift changes and they were fine on the first two passes. However on the 3rd and last pass it hit the rev limiter in 1st and 2nd as it cooled into the mid 70s. I think I need to move the mph by a couple. It ran 11.18/125/1.63 and 11.21/125/1.64 and the last pass it went 11.36/124/1.63 hitting the limiter. It probably would have picked up a little but I had to much fuel in the car as I miss calculated how much I have after I drove 155 miles from home to the track, I had almost 3/4 tank when I made my 1st pass (11.18), last time at the track I had 1/4 when I ran my 11.18/124 so thats almost 50 lbs more then I should have had. My bad for sure plus it was a few degrees hotter this time then last.

KingLT1 · 10-15-2020, 08:54 AM

who ported the IM/TB?

laynlo15 · 10-15-2020, 09:54 AM

Katech did the TB and Weapon x did the intake according to the previous owner. He went to a ported MSD and 95MM TB on his C7. I think a lot was my fault not having similar fuel level in the car so I screwed up. I have a ported 95mm that faster prom did plus a Solar adapter that I haven't run yet. Not sure if I'll run that this year as I doubt it will help any.

Trochoidal · 10-15-2020, 04:47 PM

Quote:

Originally Posted by 6spdhyperblue

Has anyone made a calculator for the auto gear ratios? rpm x (that gear ratio x rear gear x tire height) to get the exact mph? Am I thinking about that right

We need a wallaceracing with our stuff prepopulated

I use this calculator for the results you’re pursuing.

https://www.blocklayer.com/rpm-gear.aspx

10-04-2020, 10:29 AM	#15
KingLT1 Drives: 2016 1SS NFG A8 Join Date: Aug 2017 Location: 46804 Posts: 7,666	Agree...I shifted mine at 6500 rpm. Helps the 4-5 quite a bit. __________________ 2016 NFG SS A8/Whipple 2.9/Fuel System/Flex Fuel

10-07-2020, 10:47 AM	#18
6spdhyperblue Drives: 2SS 1LE Join Date: Aug 2013 Location: US Posts: 3,794	Has anyone made a calculator for the auto gear ratios? rpm x (that gear ratio x rear gear x tire height) to get the exact mph? Am I thinking about that right We need a wallaceracing with our stuff prepopulated __________________

10-08-2020, 01:09 PM	#21
6spdhyperblue Drives: 2SS 1LE Join Date: Aug 2013 Location: US Posts: 3,794	Man that’s a mph..crazy __________________

10-15-2020, 08:50 AM	#23
laynlo15 Drives: 2022 Lt1 A10 Join Date: Nov 2015 Location: clark, mo Posts: 8,882	Went to track last night and the ported intake/Tb didn't really show any et gains and 1 mph on 2 of the passes. It didn't loose any so that is good. I did make some shift changes and they were fine on the first two passes. However on the 3rd and last pass it hit the rev limiter in 1st and 2nd as it cooled into the mid 70s. I think I need to move the mph by a couple. It ran 11.18/125/1.63 and 11.21/125/1.64 and the last pass it went 11.36/124/1.63 hitting the limiter. It probably would have picked up a little but I had to much fuel in the car as I miss calculated how much I have after I drove 155 miles from home to the track, I had almost 3/4 tank when I made my 1st pass (11.18), last time at the track I had 1/4 when I ran my 11.18/124 so thats almost 50 lbs more then I should have had. My bad for sure plus it was a few degrees hotter this time then last. Last edited by laynlo15; 10-15-2020 at 09:07 AM.

10-15-2020, 08:54 AM	#24
KingLT1 Drives: 2016 1SS NFG A8 Join Date: Aug 2017 Location: 46804 Posts: 7,666	who ported the IM/TB? __________________ 2016 NFG SS A8/Whipple 2.9/Fuel System/Flex Fuel

10-04-2020, 01:22 PM	#16
cmitchell17 Drives: 17 2SS, 8L90, Cam, Heads, E85 Join Date: Dec 2016 Location: US Posts: 1,213	Its a huge PITA to get these things to shift where it needs to, and its still usually extremely inconsistent from shift to shift. I had to just sit there and adjust WOT shift MPH by 1 and flash, then try it, then flash again, and repeat, it takes forever. If you have bad tires and bad traction its going to hit the limiter easily. I tried to adjust the RPM limiter acceleration rates to not cut fuel as early as it does stock, so in case it spends and the transmission can't shift as fast it won't hit the limiter. If it does get into the limiter it cuts power back severely and ruins the run.

10-07-2020, 06:38 AM	#17
laynlo15 Drives: 2022 Lt1 A10 Join Date: Nov 2015 Location: clark, mo Posts: 8,882	I moved all mine up 2 mph and 100 rpms starting in the 2-3 shift. Should get plenty of TNT on Saturday to have time to make adjustments if needed.

10-08-2020, 12:34 PM	#20
laynlo15 Drives: 2022 Lt1 A10 Join Date: Nov 2015 Location: clark, mo Posts: 8,882	My Camaro used to shift into 5th about 1000 ft I would guess and that last 320 feet goes pretty quick and then trapping at 147 to 149 mph.

10-15-2020, 09:54 AM	#25
laynlo15 Drives: 2022 Lt1 A10 Join Date: Nov 2015 Location: clark, mo Posts: 8,882	Katech did the TB and Weapon x did the intake according to the previous owner. He went to a ported MSD and 95MM TB on his C7. I think a lot was my fault not having similar fuel level in the car so I screwed up. I have a ported 95mm that faster prom did plus a Solar adapter that I haven't run yet. Not sure if I'll run that this year as I doubt it will help any.

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