Smooth Throttle for UpRev

Awgd8

POST#8 by wstar on the 1st page of this thread.

Originally Posted by Jordo! View Post
Awesome, thanks -- I will pass this on


"Driving Force" appears to = Load and "Flow Potential" is either VE or MAF counts (or a calculated perecentage based on both).

Load is based on RPM, VE, and g/sec of metered air, so that's probably about right.

WSTAR : " Yeah the table still doesn't make intuitive sense to me though. The tuner I used (as in, the dyno-tuning professional) seemed to know what he was doing and set all "3800" values in the last few columns though, and that seems to correspond to WOT at full pedal. "

It's clear from experimenting that this table does affect how the throttle reacts to pedal input, but both of the non-obvious labels seem like secondary effects. The position of the throttle butterfly will determine airflow, and that combined with RPM is pretty much going to define load or driving force or whatever. It just seems like one of these axes must be mislabeled for this to be a throttle table.


I wish wstar can chime in here... My AWGD8 # 3 MAP is at 4300 MAX. It might fully open pass the 3800, but not sure. All I know is there is a certain max at a certain flow potential %. As I mentioned on my MAP #3 . I lost a little bit of seat of pants pull when I reached the 50% flow potential as you can see on your MAP curve. ( the highest point @50% ) Those number weren't even close to 3800, but I did feel a strong pull from the middle of midrange to top end and those are around 3600-4300....

BTW, I just happened to noticed while looking at the curve Graph you posted, that my AWGD# blend 2/3 MAP looks a bit the same curve with the stock G37 MAP. It just happened that the Blend MAP power comes in earlier with a less throttle/pedal push....No wonder why I like it BEST!

V1H

I see what u mean

And on Wstar's comment that a linear curve wouldn't result in a steady throttle valve opening towards the upper end.. I think I know why that may be. It's a simple trigonometric relation. Opening an almost open butterfly a little further has much less an effect on additional air flow than doing so at a half opened butterfly. Therefore the ECU may have a built-in non-linear interpretation of throttle curve to actual throttle position. If that makes sense.
If all was purely geometric and idealistic this non-linear relation would simply be sinosoidal in shape. Some call this the "S" shape in a throttle map, which is a part of a sine square function. But I wouldn't be surprised Nissan also accounted for other physical parameters (partial pressure, turbulence, etc) which will probably make this non-linear relationship more complex than a simple trig. function.
In order to "reverse engineer" this non-linearity one would really have to play with throttle curves, point by point, until the datalog of the TPS becomes linear with accelerator pedal. That would of course be a huge PITA to do
And on top of that you'd have to repeat everything for all other rpms, coz flow characteristics change with rpm. (No motor has a perfectly flat volumetric efficiency across the rpm range)

Awgd8

Pm

juicinjake

i might be able to offer some insight as to why they did this. i just got my vhr car a month ago and have yet to mess with tuning it, but i have extensive r&d/tuning experience with a radical revup combination that i developed outside the light of the public forums. i tune this car myself using an aem infinity standalone ecu. the car uses a large single ported 87mm gm throttle body (along with a custom intake manifold that i also built) which brings its inlet airflow cross-sectional area on par with that of the hr and vhr. prior to this i attempted to make this work on the stock ecu and found the limits of the system, as well as experienced a lot of the frustrations you guys have been going through with this, minus the vvel connection. it becomes apparent after messing with it for a while that what uprev supplies you as a throttle map doesnt exactly directly control the throttle like you wish it would. in fact that map literally does nothing anytime the ecu sees that the engine is operating within the idle range. that said, what everyone always wants with regards to throttle control is what the standalones provide... a throttle position vs pedal position/rpm map. now, given that i have been able to experiment with a comparable amount of inlet airflow (potential) as the hr/vhr cars, but with the ability to control the throttle in this fashion, i can see why the power delivery is designed to be s-shaped. i was able to set the throttle table up, relative to pedal position, in a completely linear fashion with the aem. what might not be readily apparent is that the engine doesnt necessarily increase its airflow potential relative to throttle position. so, what you find with a big 87, or a pair of 60's, with a truly linear throttle curve is that it is way, way, way too responsive at low throttle angles to the point that it makes low speed maneuvering jerky and awkward, while shifting becomes annoying, uncontrollable and unpredictable. i have a triple carbon disc clutch that without the rjm bracket is more or less an on/off switch. the bracket allows you to slip the clutch effectively enough for the car to drive and shift closer to that of a stockish car. well, that all goes out the window if the engine response is ultra sensitive at low throttle angles. what i did to fix this was dampen the throttle response, relative to sub-50% pedal position below 4k. the map is setup such that the x-axis is rpm and the y-axis is pedal percentage... while the map content is throttle position. with my gearing/tire combination all cruising and general commuting is done under 4k, so this works out very well. i rev to 8k, with the real meat of powerband beginning a little after 5k. throttle response is practically instantaneous on my setup. its very easy to get into the powerband when you want to. this way, any time you are more than 50% into the pedal, regardless of rpm, the car acts as if it has a cable throttle control... yet it is predictable at low throttle angles and rpms and easy to move slowly and shift. i sold my uprev cable prior to buying my aem, not knowing i would have a vhr car in another few months. i plan on buying uprev again and experimenting with this very sort of thing (although im "supposed to be leaving the car alone"). hopefully, once i can tune this new car/engine and gain some experience with this new cam timing/throttle control arrangement i can be more helpful. great job so far guys, this thread made a very interesting read!

maxjix

left : 09 g37 sedan
right : 09 g37 coupe

All of the tables is the same

but
Throttle enhancement table are different.

Jordo!

What exactly do those tables seem to do?

__________________
Enjoy it. Destroy it.

V1H

Hi juicinjake
Interesting story. You seem to have the right expertise with throttle map tuning to get us all a step forward with how to best program the UpRev throttle map.
Looking fwd to hearing more