when you're running a fully programable engine management system are you almost always able to tune out dips in the torque curve?

for example, if you've created an almost perfectly flat a/f of 12.5 with a proper ignition curve, and there are still torque dips, would that just be a characteristic of the engine, ie. cam, header, head, turbo or boost combo?

i know this is kinda vague and hypothetical, but if you guys can give me some thoughts on this subject it would be greatly appreciated.

 

Depends on the type of engine, etc.

On a normally aspirated motor with a single runner manifold design, you will have some resonance dips that can't be eliminated. The header, intake (in front of the throttle body), etc. can also cause some dips, bumps due to resonance effects. Often times, if you have good measurements on these things (and simulation software in the case of the header), you can even calculate where these resonance effects will take place before the motor is even built.

On a turbo motor, you should be able to get a relatively smooth, broad torque curve once the turbo is spooled up.

Lots of other stuff to consider, but those are the basics.

C_A_T

 

CAT,

have you seen any dyno plots for toda itbs w/ vtec killer cams? is there anything in this combination that would inherently cause dips?

in a turbo car, if the boost curve varied up and down 1 or 2 psi in the datalog would that cause the torque curve to lose the smoothness?

thanks!

 

I have not seen any Toda ITB dynos. There should still be a resonant peak depending upon runner length, but the lack of plenum/intake may eliminate some other peaks/dips.

A 1-2 psi variation won't show much change in the torque curve on a high boost motor (14-15 psi or more), but if you're running 5-6 psi, then yes, you could expect to see some small changes. However, boost levels do not necessarily equate to airflow levels, and other aspects of the engine combo can affect boost. Thus, the boost variation may not effect the curve (visibly) at all.

C_A_T