Achieving a better torque curve?

[AgaBoogaBoo]

What are some things a car manufacturer can do to affect the torque curve?

I thought of this after thinking about next year's RSX-S and how the torque curve has been modified.

 

[NutBucket]

Change the cam timing (ie of each cam). That's the purpose of adjustable cam gear(s).

EDIT: Intake and exhaust manifold design play a role in this as well. For example, a 4-2-1 header will produce more midrange torque then a 4-1 header. The tradoff is that the 4-1 header is much better for top end.

 

[Eli]

The biggest things effecting torque curve are the cut of the camshaft and the engine's stroke.

You can change the torque curve all over the RPM range with changes in the camshaft lobes, ie: valve lift and duration in relation to piston position.

 

[AgaBoogaBoo]

Originally posted by: NutBucket
Change the cam timing (ie of each cam). That's the purpose of adjustable cam gear(s).

EDIT: Intake and exhaust manifold design play a role in this as well. For example, a 4-2-1 header will produce more midrange torque then a 4-1 header. The tradoff is that the 4-1 header is much better for top end.

what about lowend torque?

 

[notfred]

add displacement.

 

[Eli]

Originally posted by: notfred
add displacement.

Adding displacement by increasing bore will increase torque, but it won't change the torque curve.. at least not like an adjustment in valve duration/lift and/or a displacement increase via an increased stroke would.

 

[mAdD INDIAN]

Airflow management is a big factor in torque curves.

Depending on how the air flows into the combustion chamber from the manifolds can greatly affect the torque curve. At low RPMs, you want a slower air flow to optimize torque, but at high RPMs you need much faster airflow if you want to generate power. Now coming up with a multi-stage intake manifold that can offer different airpaths at different rpm ranges can go a long way to generating useful torque curves across the entire rev range. That's why you'll see modern cars with dual runner intake manifold,that is they offer a short path at high RPMs and long path at low rpms.

Hope that helps. I"ll give more info tomorrow. Gotta sleep now.

 

[TechnoKid]

turbo'd cars have pretty flat torque curves, take for example the Audi 1.8T engine.

 

[olds]

Take the 455 out of my boat and put it in your car.