Quote:
Originally Posted by badmfkr 
Jon I said that to get feedback.
looking for replys like
1.drivabilty
2.stealthness
3.more low end power
4.being able to add more timing campared to a bigger cam.
but most of all not getting all the use out of a set of expensive heads.
Thanks |
A very basic way to look at this is:
The head determines the
height of the entire torque curve and the cam determines how the torque curve "rotates" about the max torque rpm point.
So you can have good low end torque as well as high end power with a great head and a fairly tame cam. You don't get that from a poor head and cam no matter what the cam. We've all seen high hp at 6500 rpm combinations be down 30-50 lb-ft at 3000 rpm because a long duration cam needed to be used to get the hp number.
A fat, flat trorque curve, like 350 to 400 lb-ft (rw) from 3000 to 6500 makes a very driveable car and still makes about 450 rwhp @ 63-6400 on an A4 346 engine. That fulfills your 1. thru 3. above. Not sure why you want 4.
One way to look at a combination is to compare minimum torque to maximum torque throughout the rpm range you plan to run. in the 350-400 example noted there is 87% of MAX torque available from 3000-6500 and 80% of max torque available from 2500 to 6600.
I like to look at the rpm band for 80% of max torque to get an idea of driveability, especially the lowest rpm where 80% of max torque occurs. 2500 rpm is nice.
Done correctly with excellent heads and matching cam, a 510 rwhp 402 can have 80% of max torque @ ~2000 rpm That's driveability, stealth and low end.
Jon