Low end torque

[Kodak]

Are there any moderately simple ways to shift the torque curve down?

Torque peaks at somewhere around 2800 rpm on my GM inline 4, but it seems that a lower rpm for max torque would allow sooner shifts, as well as the ability to hold 5th gear longer (ex. on hills).

I am familiar with the camshaft mod on the 65+ mods list, but that is way too involved for my skill level. Maybe there are some easier methods.

Thanks for any suggestions.

[Patrick]

Move the timing belt on the cam pulley a tooth or two?

[Frank Lee]

Can't think of any simple or cheap ways to move the torque curve down... that cam timing thing would be my 1st choice, followed by a different cam itself, small tube headers, perhaps a heavier flywheel, and the like. Otherwise maybe you need to be satisfied with the torque characteristics it has and work on reducing parasitic losses- eliminate belt driven stuff, underdrive the rest, improve aero, all that jazz.

[HAHA]

Manipulating the air intake is a known method to tune the torque.
Some engines utilizes variable length intakes to optimize torque for a wider rpm-range.

Lowering the weight of the vehicle will give you many benefits somewhat similar to more engine torque.

A heavier flywheel may give you better low end torque. However, this has been argued not be good for FE (at least P&G).

[ecomodded]

Maybe you should/could chip tune your 4-banger and bring it alive. It could be that the giving amount of fuel to air ratio is too low at the lower rpm's to offer any torque.
if you are on a budget try the Evry mod.

[jakobnev]

A slight ignition timing advance is the simplest mod.

I suppose a variable geometry exhaust is too involved?

More port inductance at low revs would improve torque by better scavenging, but it would also reduce cylinder temps which would allow even more timing advance.

[Ecky]

I'd suggest advancing the ignition timing 1-2°. I've read that (on Hondas anyway) every degree advanced you move on ignition timing moves the torque curve down about 300rpm. Go too far and you'll start getting predetonation, but typically 1-2° is safe. You'll hear it if there's predetonation, it generally sounds something like marbles dropped on glass.

To advance ignition timing, first make a line on your distributor and motor at the stock setting (often 16°) and the turn the distributor slightly. The direction that makes idle go up is advancing.

If you have a timing light, the flywheel has markings for stock, -2° and +2° usually.

[Diesel_Dave]

Originally Posted by Kodak

Are there any moderately simple ways to shift the torque curve down?

Buy a diesel

[JRMichler]

Your engine comes stock with variable valve timing. That's how they get 185 hp out of 2.9 L. My 2.8 L (earlier version of your engine) has trace knocking at low RPM in warm weather, so I don't believe there is any room for improvement by advancing ignition timing.

I can accelerate, although slowly, from 20 MPH in 5th gear on a level road.

[Kodak]

Originally Posted by jakobnev

I suppose a variable geometry exhaust is too involved?

Yeah, I'm not too great of a tinkerer, but thank you for throwing it out there as a possibility.

JR, thanks for clarifying the VVT situation. I'm still surprised at how low you go with 5th, as I've expressed before. Perhaps your better aero (topper) takes some of the required throttle position out of the equation, but if you're geared the same as me (3.73) with the stock tires, then we have matching engine speeds.

My engine can do 45 mph in 5th comfortably at 1500 rpm. Any lower and a mild low vibration tells me urges me to downshift. Oddly, the shift-indicator light does occasionally pop on at 40 mph, when I'm on flat ground and babying the throttle.

I've heard of tunes helping some guys out in this department.