XHP V3

[smiddy 76]

I'm similar to John in mods, have MHD 1+ tune, started at 8.0, now at 9.1 also running XHP stg 2 V3.

More than happy for a daily, have stage one turbo upgrades ready to go, ( similar in spec to RB One's), as my OEMs are whineing.        Will look at a custom map to assist with increased air/fuel flows etc.

[jon dee 500]

LIMIT TORQUE BY GEAR  Thought I would tag this on here.... apologies if there is already a separate thread.

Since there does not appear to be any way of getting the trans to start in 2nd gear when in Sports mode, I am wondering if using  xHP's "limit torque by gear" would be a good way to allow starting in 1st without the engine falling in a hole when the wheels start to spin. My thinking is that it would do much the same thing as MHD's "boost by gear" mode, but may be a better solution due to more recent development. I also like the fact that xHP includes a few presets.

Anyway, if anyone has tried the xHP solution I would appreciate any comments / impressions / comparisons.

Cheers...

[Herbmiester 923]

Not tried XHPs version but do use MHD boost by gear which certainly helped my launches. Set 1st to 10psi and virtually eliminated the rear end breaking away just before it changed to second. 

[jon dee 500]

On 10/17/2020 at 2:58 PM, jon dee said:

Since there does not appear to be any way of getting the trans to start in 2nd gear when in Sports mode, I am.... etc.

As it happens, I chanced upon some information that shows a method of making this work. Start the engine >>> move the shifter to the left >>> pull the shifter back one click and the dash will show that you are now in M2. Release the brake and accelerate. While the engine is building revs in M2, quickly slap the shifter to the right and then back to the left.... BAM... you are now accelerating in S2  

Tried this under modest acceleration and it does work. Didn't notice any hesitation or other side effects, and I don't think there should be any as the trans never leaves 2nd, but I will try it a few more times to be sure... to be shure

Cheers...

 

[Herbmiester 923]

21 hours ago, jon dee said:

As it happens, I chanced upon some information that shows a method of making this work. Start the engine >>> move the shifter to the left >>> pull the shifter back one click and the dash will show that you are now in M2. Release the brake and accelerate. While the engine is building revs in M2, quickly slap the shifter to the right and then back to the left.... BAM... you are now accelerating in S2  

Tried this under modest acceleration and it does work. Didn't notice any hesitation or other side effects, and I don't think there should be any as the trans never leaves 2nd, but I will try it a few more times to be sure... to be shure

Cheers...

 

But is it a quicker way of accelerating?

 

[jon dee 500]

3 hours ago, Herbmiester said:

But is it a quicker way of accelerating?

Probably will be for me, but primarily I just wanted the option of starting in 2nd and using sports mode to shift gears. Hopefully, that plus DTC should eliminate the HUGE stumble caused by DSC intervention when starting in 1st and giving it a big shoeful. Sports mode in xHP stage 3 is pretty damn good and I want to see how it stacks up against Manual, and of course I would be starting in M2 if I was changing gears myself

I believe that some BM models have the option of always starting in 2nd gear unless the car is doing a hill start or towing. Second gear starts are said to improve the driving experience (talking about 8-speed AT in drive mode here). Eliminating an unnecessary gear shift and making full use of the torque converter makes good sense to me. So I will play with that and see how it works before I start looking at Torque or Boost by gear to make 1st gear starts more civilized at club events.

Cheers...

[Herbmiester 923]

I am not convinced this is the best way to go about this unless its just so you can get a bigger turbo roll on effect.  As stated by limiting boost in first gear you all but eliminate the bog. I have read about launching a manual in second and it is brutal on the clutch as well as being slower. 

[jon dee 500]

Second gear starts in a manual are brutal on the clutch unless you have enough torque to spin the wheels for long enough to get the car up to a speed where the engine does not drop out of its power band when the tyres stop slipping. So basically if you can smoke the tyres in second you're good On the other hand, second gear starts in an auto don't have any ill effect on the torque converter (a type of fluid coupling) as there is no mechanical connection, just oil getting flung from one half of the coupling to the other.

The torque converter actually has the ability to multiply input torque when the speed of the driven (output) shaft is low. XHP have written a response to this question and without looking it up, the essence of what they wrote was that second gear starts don't harm the transmission.

And I had the chance to test a bit of this theory at the street sprint today. Did two runs under similar conditions, one run in Sport with a 2nd gear start, and one run in Manual with a 2nd gear start. Sport mode 97.33sec versus Manual at 97.79sec. So in this highly unscientific test the car shifted gears better that I did !!! That being said the driver made a few mistakes in both runs so not really a true comparison. For the manual run I actually brake boosted the start (DTC on) and after the run a pretty knowledgeable competitor and friend of mine commented... that car of yours gets off the line quickly !!!!

Potenza RE003's worked well in the wet under braking and acceleration. Predictable in the dry as well when giving it heaps

Cheers...

Edited November 4, 2020 by jon dee
Typo...

[Herbmiester 923]

zero to sixty did testing on second gear starts and the verdict was that its slower. 

[jon dee 500]

On 11/4/2020 at 8:12 PM, Herbmiester said:

zero to sixty did testing on second gear starts and the verdict was that its slower. 

60km/hr ? I'd guess that demonstrates the benefit of your boost by gear setup... allowing you to get away in first gear with without excessive wheelspin. I'll be having a play with boost (or toque) by gear when I get keen. Reality is that I only ever do full throttle starts at events, so for normal driving first gear starts are fine.

Cheers...

[smiddy 76]

I had a bit of a tussle with a M60 M5 couple of days back.

Motorway on ramp lights, started in second, traction off, got about car length ahead, even from there till about 130kmh, buttened off, but he was starting to gain.

Boosted stock turbos go well from a dig in second gear imo.

[Herbmiester 923]

On 11/6/2020 at 12:36 PM, jon dee said:

60km/hr ? I'd guess that demonstrates the benefit of your boost by gear setup... allowing you to get away in first gear with without excessive wheelspin. I'll be having a play with boost (or toque) by gear when I get keen. Reality is that I only ever do full throttle starts at events, so for normal driving first gear starts are fine.

Cheers...

No zero to 60 is a YT channel that has a big focus on N54 tuning, testing and modifying. Most comprehensive actual testing you will see. times were 0 to 100kph.

[Herbmiester 923]

Without an LSD I have worked out that somewhere between 10 and 12 psi of boost is all the chassis can handle on dry chip seal roads before it sets the Xmas lights on or wheel spins. If I had an LSD or I was on a stickier surface It would be different. I has improved since I put in the M3 control arms as the bushes were much firmer and it seemed to all but eliminate the odd bit of axle tramp I would sometimes get. Fitting subframe buses and a diff reinforcement support supposedly also helps. I also noticed that when I went linear throttle I has less slip. Trying to figure why but can only assume that the throttle just opens a bit slower and allows a bit more forward momentum before the turbos really spool up. Need to get the old girl sorted so I can do more testing with the Dragy.

[jon dee 500]

Since the purpose of the "linear throttle" function  is to smooth out the high initial torque rise of the turbo engine, I would expect that the DME controls the throttle opening to produce a more gradual rise in torque through the lower rpm range. And if that is the case, then it will have the same effect in softening the initial torque rise as boost by gear or torque by gear. Whether the linear throttle effect is achieved by controlling the throttle opening, wastegates and/or a combination of these and ignition timing is something only MHD would know. However, when you stomp the gas pedal to the floor, you are signalling the DME that you don't care about linear throttle, so in theory it should go straight to full noise If it doesn't do that and you get less slip, the settings must still introduce a bit of "lag" into the torque rise.

Did you measure any difference in 0-100 times between linear throttle on and off ?

Cheers...

[Herbmiester 923]

1 hour ago, jon dee said:

Since the purpose of the "linear throttle" function  is to smooth out the high initial torque rise of the turbo engine, I would expect that the DME controls the throttle opening to produce a more gradual rise in torque through the lower rpm range. And if that is the case, then it will have the same effect in softening the initial torque rise as boost by gear or torque by gear. Whether the linear throttle effect is achieved by controlling the throttle opening, wastegates and/or a combination of these and ignition timing is something only MHD would know. However, when you stomp the gas pedal to the floor, you are signaling the DME that you don't care about linear throttle, so in theory it should go straight to full noise If it doesn't do that and you get less slip, the settings must still introduce a bit of "lag" into the torque rise.

Did you measure any difference in 0-100 times between linear throttle on and off ?

Cheers...

I did some testing with the Draggy but there too many other variables at play including the updated map and the boost by gear settings. I was right on 5.1with this setup  and before that 5.4.

[jon dee 500]

You just reminded me that I have a Passport GTimer sitting on the shelf above my desk It's another one of those speed / distance / power gadgets except this one works off a 3-axis accelerometer for making its calculations. I bought it years ago and stopped using it when I got hold of an Apexi RSM. I'll have to recommission the GTimer to get a few performance figures as it is a lot quicker and easier to use the GTimer than to make logs and extract the data for Virtual Dyno. From memory, I don't think that it is fussy whether you use second or third which should make it easier to find somewhere to do some testing.

Cheers...

[Herbmiester 923]

I had a G-Tech back in the day but like most of those accelerometer devices they were a bit hit and miss. GPS based stuff like the Draggy is cheap enough now.

[Olaf 3317]

@Herbmiester is Draggy a phone app that gives you performance figures?  Could putting this on my phone be like +10hp for my mighty M40B16?

 

[Herbmiester 923]

2 hours ago, Olaf said:

@Herbmiester is Draggy a phone app that gives you performance figures?  Could putting this on my phone be like +10hp for my mighty M40B16?

 

Draggy is a stand alone device you place in the car it uses GPS to calculate acceleration. It Bluetooth's to your phone.