Low end torque

[Frank Lee]

Regardless, I've played with distributor timing systems and advancing it a few degrees did nothing for seat-of-the-pants torque that I could tell, so I don't think it's a viable method for avoiding that downshift on a hill.

[Ladogaboy]

Like I said, I can only speak for my own car on this matter (since I've done a significant amount of research), and other owners have seen significant improvements simply by increasing the ignition timing across the various load and rpm ranges. These improvements include increased power, smoother power/torque curve, and increased mileage (as much as 20% in some cases).

Again, the best course of action would be to check car-specific forums for more information on car-specific tuning. There is probably a significant amount of information on Japanese cars in particular, and the reason for that is Japanese tuners have a tendency to focus on ignition timing for performance tuning (as opposed to most American tuners who focus primarily on seeing how much more gas they can flow through the engine).

[Frank Lee]

Perhaps those who got +20% had timing that was way off before? A couple degrees doesn't make a dramatic difference no matter what system or make or model it is.

[Ladogaboy]

Originally Posted by Frank Lee

Perhaps those who got +20% had timing that was way off before? A couple degrees doesn't make a dramatic difference no matter what system or make or model it is.

It could if it's a matter of keeping your turbocharged car out of boost and in a leaner AFR. And again, the effects will be platform specific. Besides, this thread isn't just about fuel economy, it is about low-end power and "drivablity." And that, a couple of degrees of timing can improve.

[Kodak]

Let me see if I understand this correctly. Suppose I decide to skip any drivetrain mods and do some aero and weight improvements. Does this scenario check out?:

A throttle position of X is currently required to maintain 40 mph in 5th gear on level ground with no major wind. There is a slight engine vibration, so I decide to downshift, despite JR's success with even lower speeds. If aero is improved, and now the throttle position is X-2 units (sorry, not sure how it's measured), will the engine be more comfortable at 40 mph still in 5th?

So although engine speed has to stay the same, can a lighter throttle position to maintain speed help the engine be more comfortable at these lower rpms?

Or maybe I'm still way off.

[HAHA]

Yes - a bit like driving slightly downhills if you want to test what it feels like.

[Michael Moore]

Originally Posted by HAHA

A heavier flywheel may give you better low end torque.

Actually, it won't affect torque at all. Torque is a function of the engine tuning.

Extra flywheel mass may help an engine to run smoother at low speeds, or a lighter one may give quicker acceleration, but it has no effect on the power being produced by the engine.

An engine with very light flywheel mass may have plenty of torque, but if run right at idle it could be prone to stalling if something drags the RPM down just a tiny amount. Put a heavier flywheel on that same engine and you'll find that it will chug along, and the extra mass helps it to ignore any minor changes that would have the light flywheel vehicle stalling. I've noticed that on trials bikes. My Kawasaki vintage trials bike has a fairly light flywheel (for a trials bike) and it may stall if it hits a little bump when running right at idle, where a Bultaco (with a much heavier flywheel) will keep going.

A heavier flywheel may also make the vehicle less prone to slowing down at high speeds if there's a gust of headwind. The flywheel keeps things moving. Some teams will run a heavier crankshaft/flywheel at tracks like Daytona so that gust of headwind doesn't drag the engine down out of the powerband. The Honda 6 cylinder GP bikes of the 1960s had so little flywheel that if the throttle was shut at high RPM when the transmission was in neutral they pretty much just stop running.

cheers,
Michael