Shift earlier for TQ.. thoughts this experiment ?

T

TopherSho

New member
Ok,  I finally have a 'final' tune from AJP Turbo,  (who btw .. is THE man).  And it is track time.

From my older car track experience with a G35 NA,  shifting before the TQ cliff resulted in better 60' and 1/4 mile times.  With my dyno and a few others it looks like some of us might benefit in the 60' and 1/4 doing the same.. Yet I have not seen the same topic brought up here which surprised me given the number of Dynos showing dipping end run power curves.

This is my experiment::

lower the 1-2 upshift from 6100 rpm to 5500 using the hand-held, not manual shifting.  This is to HOPEFULLY to push the resulting shift to 2nd RPM window left to 3900rpm-4000rpm based on the pic below instead of 4445@ rpm where the data log shows it resulting after 11 averages.  To do this i am 1st going to try commanding the shift @ 31mph instead of the OEM 35.7 mph where it shifts now under WoT.

w1qvz9.jpg


based on *my* dyno (mustang dyno @14.5 spark) I loose 50-lbft after 5200 rpm,  and loose around 25-hp.  Worse I am on a full TQ/HP downward curve the whole way from shift to shift, Add to this the RPM time dilation (it takes longer to build each rpm past 'point-x' than (point-x)-1) .. I might be crazy,  but the loss of 10hP to gain 30+ftlb AVG  in the proposed operation range may be actually beneficial.  Added to this the lower RPM-time-dilatation I think it should net me real measurable gains on 0-60 and 60' drags and a finale 1/4 ET.  Since no matter what we have 2 gears shifts 0-60 and 4 in the 1/4 it cant hurt to try.. :)

*IF* i see a logged 0-60 that is better by 100ms or more I will retest lowering the shift by 1 more MPH for a probable 3800RPM second gear start and re-logging.  After getting the 1st gear dialed in if it is beneficial I will also trim the 2-3 shift as well

So.. I'm going for it today regardless (FOR SCIENCE!) and tinkering and testing.  I Will post a log later. But I am curious on peoples thoughts and bets .. :P  Speculate away at my expense!



 
I was wondering sort of the same thing given our high torque Bias and my car's propensity for smoking off 1st gear.  I wish there was a way to launch in 2nd gear(brake boost to 1800-2k range).  I think it would net a better transfer of power without roasting tires?

Having that Dyno info is very telling to be able to tune trans in for best ET by maximizing use of your power envelope.  Shifting at slightly lower rpm might also ease the load on the Fuel system as well?
 
:) well for SCIENCE!  I going to find out for sure for my car at least. :) ..

You *can* run in manual shift mode and start the car in 2nd.  However loading 300ftlbs onto second gear that way .. I do not know if that's safe ?  Others would need to chime in ..
 
I wouldnt start in 2nd...the shifts happen so fast and you keep forward momentum unlike a stick car..i bet it would feel lazy

Everytime you flash some cars reset the kam and if yours does that your oar will not be set and you wont be getting full spark until you drive some so keep that in mind when flashing and testing
 
AJP turbo said:
Everytime you flash some cars reset the kam and if yours does that your oar will not be set and you wont be getting full spark until you drive some so keep that in mind when flashing and testing
Click to expand...

Yup we talked about that a few weeks ago as I recall!  I will be mindfull..
 
Well that's disappointing.. it is not respecting the hand-held SCT tuner 'option'.  I flashed to the revision-11 tune and checked the box for -3 MPH on WoT  for 1st gear and it is still commanding the gear change at the exact same place as the previous datalogs, 36.5+ MPH..

hmm  I am going to email SCT and ask why that may be ..

Attached the 4 0-60's.    They are brake-to-gas runs,  no power braking.
 
AJP turbo said:
Ill fix you up....i dont like the end user options for shift changes anyway
Click to expand...

I might drive out and hug you.. <3  but before you make the changes I was LIMITED to -3 on the handheld.. I would like to shift at 31MPH so that would be -5.5 from the OEM setting For this first test.

Currently all the logs have the gear change command issued at 36.5+ mph. 
 
AJP turbo said:
Ill fix you up....i dont like the end user options for shift changes anyway
Click to expand...

well i'm sure that damn thing modified a cell\table SOMEWHERE by reducing the value by 3... that's horrifying.. wonder what it did touch :P
 
In my case me and Brad decided to lower shift points to keep WGDC from maxxing out at higher rpms and to control boost spike. It commands the shift right around 5700rpms. I do plan on experimenting a little with manual mode at the track. I would imagine you might be able to pull a quicker 0-60 if you let the rpms run out a little longer rather than commanding a shift around 58mph and adding another shift to the time.

Big thing to keep your eye on when experimenting though is your FRP. If you shift early you'll drop to about 4k rpm or lower, the boost spike will occur and load will be high . . . . all of course while your cam driven fuel pump isn't spinning as fast. Kind of a recipe for low FRP really.
but there's always the wonderful AJP boost regulator mod ;)
 
Colorado-SHOBro said:
In my case me and Brad decided to lower shift points to keep WGDC from maxxing out at higher rpms and to control boost spike. It commands the shift right around 5700rpms. I do plan on experimenting a little with manual mode at the track. I would imagine you might be able to pull a quicker 0-60 if you let the rpms run out a little longer rather than commanding a shift around 58mph and adding another shift to the time.

Big thing to keep your eye on when experimenting though is your FRP. If you shift early you'll drop to about 4k rpm or lower, the boost spike will occur and load will be high . . . . all of course while your cam driven fuel pump isn't spinning as fast. Kind of a recipe for low FRP really.
but there's always the wonderful AJP boost regulator mod ;)
Click to expand...

So this has been bugging me.. what is the difference in the PTU upshifting at 5500rpm by programing versus the user doing it with the paddles?  If anything i would think the paddles were worse since the upshift timing seems shorter and crisper than the automatic upshift..

thoughts ?
 
I wondered this myself and if my tranny would behave I'd try 6750 or whatever RPM was needed to not breech 6750.

If you have DMRs enabled you could plug your torque curve into this calculator.

http://www.ecoboostperformanceforum.com/index.php/topic,5796.0.html

I ran a few different dynos and the results were the same showing the stark differences between PP/nonPP.

Whether this holds up in the real world, IDK, maybe the MKS will behave better so I can test it at the track.
 
FoMoCoSHO said:
I wondered this myself and if my tranny would behave I'd try 6750 or whatever RPM was needed to not breech 6750.

If you have DMRs enabled you could plug your torque curve into this calculator.

http://www.ecoboostperformanceforum.com/index.php/topic,5796.0.html

I ran a few different dynos and the results were the same showing the stark differences between PP/nonPP.

Whether this holds up in the real world, IDK, maybe the MKS will behave better so I can test it at the track.
Click to expand...

It dried enough to make some runs into 3rd.  I will check the logs and post them in a bit (ice cream run).. 

There was definitely more wheel spin/hop on engaging 2nd.  But there was also a scary 'blip' where it either spun the tire again or the fuel cut. 

Logs will tell..
 
TopherSho said:
FoMoCoSHO said:
I wondered this myself and if my tranny would behave I'd try 6750 or whatever RPM was needed to not breech 6750.

If you have DMRs enabled you could plug your torque curve into this calculator.

http://www.ecoboostperformanceforum.com/index.php/topic,5796.0.html

I ran a few different dynos and the results were the same showing the stark differences between PP/nonPP.

Whether this holds up in the real world, IDK, maybe the MKS will behave better so I can test it at the track.
Click to expand...

It dried enough to make some runs into 3rd.  I will check the logs and post them in a bit (ice cream run).. 

There was definitely more wheel spin/hop on engaging 2nd.  But there was also a scary 'blip' where it either spun the tire again or the fuel cut. 

Logs will tell..
Click to expand...

Logs... I could not tell if there was a fuel issue or it spun the tire halfway through second.. but it definitely had a power interruption for less than 250ms
 
The shift to 2nd is hooking up at a reported 4200rpm. So thats better but i would like to try for 4000.. 
The shift to third hooks up at 4000 +/- 50 rpm so that's awesome...

gear changes are happening at 31mph avg and 52.5 avg ..

Yet the time in LiveLink shows faster 0-60 for the 1st test,  but slower for the next 3 .. that baffles me.  Were shifting into much better TQ curve.  hmpf .. research time.

maybe i will make a run to 105 when i can and check that time.
 
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