Engine torque from derived torque then onto virtual torque tables

[hjtrbo]

Hey all,

Honestly a little bit embarrassed to ask this but is it possible to calculate engine torque from a derived torque figure that was generated by a Mainline chassis dyno?

Thought I could just throw the gearbox ratio and diff ratio at it but the numbers like way wrong. It's making me feel really dumb. For those interested the gear ratio is 1.15 and diff ratio is 3.23. Converter locked. Peak torque was 750Nm at 140kph which is approx. 4200rpm. Tyre rev/km 473.19.

Reason for asking is my logged delivered engine torque reports nearly the same as the rear wheel torque of the dyno, but those tables are supposed to reflect engine torque. I was hoping to find the difference so I knew how much to bump up my airmass A coefficients.

 

[07GTS]

if it works as it is then may be best to keep it as it is, if u change the reading at all say 30% to estimate the change to engine from rear wheel then every table that uses torque value will be out by that amount (mostly all your trans pressures) then they will all need adjusting again to bring them back in line,
IMO id make the idle torque read as the stock idle torque reads (after camshaft change) so its in line for the idle corrections, driving decel ect. anything alse under a mid to hard throttle wouldnt matter as much as its only used for trans stuff that even if its wrong torque value it will be the same value each point so will be correct even if in error of actual

 

[hjtrbo]

Yeah like you said, probably no need to do it but I'm bored and haven't got anything left on my tune to muck around with. The thing is running perfect. Thought I'd dig a hole just to fill it back in next month... My logic makes no sense.

I took a little out ages ago from the 550 to 950 in Airmass A which helped heaps with the cam and head combo as well as increasing the throttle follower torque table in the same areas. Reporting about 60Nm now at idle when warm. Would love to know what a stock one reports at idle. The purpose of me mucking around with this is to wind the transmission tables back down towards stock and instead rely on the torque values been accurate to get the line pressure back.

It's been a while but I think you are heading down the same road with the lower torque values idle?

 

[07GTS]

yea i dont have mine at idle to compare stock but a mates is about the 0-20nm at idle which reflects the idle torque follower table setup, i also setup a tune im working on with guy from US and set it the same way for idle and seems to work well so ur not fighting the torque follower with airflow corrections, but yea if u wanted something to muck around with just log the same layout as the VTT layout for airmass/map and adjust the same area to suit estimated engine torque from the dyno readout and then populate those values back to the idle map/airmass row, dont forget the e85 VTT for yours too theres some more work once u swap over

 

[hjtrbo]

Got it.

But to clarify, for example the scanner currently shows 800 peak torque on a road pull at 21 deg advance. Just so I'm heading in the right direction that number should be reported around 1050 for example???

 

[07GTS]

yea try bump it up to estimated amount in both the map and airmass (seems to work best changing both) by adding the error to it, then blend in from idle n see where it ends up being as its not always exact can take a few goes but if its close will be fine

 

[hjtrbo]

Sweet. I'm not far off buying the ID injectors just to know the fuel model will be spot on. You were right that I can make the 1050s work. 450kPa base pressure will put me at 80% duty on e85. Was thinking all these changes will work together. And have been thinking even more that if the fuel model gets corrected with the better data that the torque model could even line up far better???

 

[07GTS]

yea if u change injectors and re do the fueling it will change the torque reading again also so best to have mechanical fueling correct then injector data correct then the fueling/air model will be much better and consistent when dialed in, i still recommend a manifold referenced fuel pressure whether u can do that with the FPCM or change to mechanical reg as that will give even more range for the injectors

 

[hjtrbo]

Going to do similar to you. AI surge tank with 2 x 460s. Had a chat to someone that done the 2nd pump on a boost switch and he said it mucked up the closed loop control of the FPCM pump when it kicked in so fuelling wasn't good until things settled out. Had a look today at a PWM setup but didnt like it. Sometimes rock solid old fashioned steady supply is fhe go. Do you reckon I'll get away with the FPR1200 regulator? ID calculator says 10,400cc/min required fuel flow at 450kPa base pressure.

I'll have to go very slow with the torque tables as I have to walk the trans pressure back. So will be little steps at a time. Will take months lol. There is a pressure test port on the trans that I would like to fit a sensor to and include in my logs.

 

[07GTS]

yea looks like that reg will suit says can flow 1200hp which is bout what the pump modules flow, if its small enough u may even be able to fit it next to the tank then just return straight back from reg to module and feed thru and back into stock feed keeping your fuel pressure sensor/flex when u get it in use and just run a line from manifold to reg if u go that way or keep it steady 43.5psi (300kpa) or 58psi (400kpa) base if u need more, i got the fuel sensor wired into mine u could just get a sensor to suit the pressure range and wire it in to hpt pro feature if u have that to log it, or ngauge if u can find one nowdays