How accurate is the hp/tq histogram?

[dleach1407]

How accurate is the hp/tq histogram?

[decipha]

I only made it to help visualize the torque curve so you know where peak torque is occurring at.

[wwhite]

I've been graphing TQ_NET(Net engine torque into transmission, ft-lb.) on EEC-IV SD E4OD, and appears to be very accurate.

TORQUE CALCULATION
OVERVIEW

The engine output torque, or net torque, is calculated from a table of
indicated torque versus speed/load, determined at MBT spark timing, 14.6 A/F
ratio and no EGR. This torque value is then adjusted by multiplying by a
factor dependent on the difference between MBT spark (adjusted for actual EGR
flow), actual spark advance, and if in open loop fuel control, by a factor
dependent on the value of lambse. This value is then further reduced by
subtracting friction torque and accessory load torque. Net torque (TQ_NET)
is used in the electronic transmission control strategy in calculating the
EPC required for "static capacity".

[decipha]

thats only going to be as accurate as your torque table is

the tq and hp payloads i made in tunerpro are based on airmass so will show you where your actual peak torque is occurring which is really all you need to know

[dnschneid]

would you say the width of the airmass-based torque curve is sufficiently accurate to use as a basis for evaluating ideal gear spacing?

[decipha]

No, cuz torque isnt the only determining factory for most optimal gear shifts.

Theres a 20+ variable engineering calculation for gearing ratios. Everything from tire friction to ambient temp, coef drag, center of gravity, wind speed, etc.. goes on to it. Thats like trying to model engine flow with limited/missing data.

Best bet is trial and error.

You could always do a gear vendors if you need to split gears or trying to get every last bit.