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Engine torque output: constant or pulsed?
(8 posts, started )
Engine torque output: constant or pulsed?
This is mostly a question for Scawen, but if anyone is able to prove it experimentally, I'm also interested.

Assuming constant RPM and throttle position, does LFS model engine torque output as a single value? Or does it oscillate with the crankshaft phase based on the power pulses (e.g. a spike in torque every 180 degrees of a 4-cylinder's crankshaft rotation)?

I'm not sure how applicable it is to cars, but at least for motorbikes, a lot of people seem to be of the opinion that wide, uneven spacing of power pulses (such as in the case of V-configuration engines, or "cross-plane" crankshafts for inlines, e.g. latest Yamaha R1 and M1) is beneficial to a rider's ability to "feel" the level of grip under acceleration at the limit, compared to evenly-spaced power pulses that nevertheless may still experience some oscillation in torque output.

If no such torque oscillations exist at all in LFS, what effect they would have if added, and are they worth the CPU time?

Does the mass of the driveline and/or vehicle damp such oscillations to the point they're practically non-existent?
I have no proof whatsoever,but I doubt that engine is simulated so complex in LFS. I would bet on constant value at constant RPM right away.
Quote from Eclipsed :I have no proof whatsoever,but I doubt that engine is simulated so complex in LFS. I would bet on constant value at constant RPM right away.

That's my guess also, but it's interesting to think about.
#4 - w126
Even at low engine RPM, e.g. 2000 RPM, there will be only 3 physics simulation steps (0.01 s) per one crankshaft rotation, so there is not enough "fidelity" for pulsed engine torque.
Quote from w126 :Even at low engine RPM, e.g. 2000 RPM, there will be only 3 physics simulation steps (0.01 s) per one crankshaft rotation, so there is not enough "fidelity" for pulsed engine torque.

That's a very good point. I completely forgot about the physics loop time. I think that alone proves the torque is a constant value.
Quote from Forbin :That's a very good point. I completely forgot about the physics loop time. I think that alone proves the torque is a constant value.

only elektro motor have stable torque .. (( 2 pi R o / 60 ))
Quote from WestlY :only elektro motor have stable torque .. (( 2 pi R o / 60 ))

I wasn't referring to the torque vs. RPM curve, and anyway, an electric motor's torque output decreases as RPM increases, so it's not entirely constant.

I was referring to the torque pulses over the course of a full, 720 degree rotation of the crankshaft, as each cylinder fires.
Quote from Forbin :I wasn't referring to the torque vs. RPM curve, and anyway, an electric motor's torque output decreases as RPM increases, so it's not entirely constant.

I was referring to the torque pulses over the course of a full, 720 degree rotation of the crankshaft, as each cylinder fires.

I think I know ( stable speed vs use gass )

all motor's torque output decreases as RPM increases, so it's not entirely constant.(Event Horizon vs. full gas)

For this reason, there are transfers ..
pulsates steering column transfers.


I think in the LFS only the effect of the wheel (tire pressure -- but i dont know - small info car in garage Smile) ... So you could only calculate the shaft for you - i don't see efect in game with crankshaft

Engine torque output: constant or pulsed?
(8 posts, started )
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