Contour Enthusiasts Group Archives Forums Modifications Duratec Performance low end question's

Lets just say that the mathematics aren't proved wrong, but if someone else were in error then the way the math was applied may have been wrong. I'm not giving you any math that you can refute and say it is wrong. I am explaining why the engineers use a dual runner intake manifold and using simple math to illustrate what happens.
I don't care if you experiment and whatever works for you is fine.
Cracking the secondaries implies that you are opening them just a tiny bit, not all the way. The relative percentage of air added by the cracked secondaries is pretty small and won't affect the intended operation of the system too much... i.e. The velocity isn't slowed much if at all and you should notice little to no change in the torque of the engine. Cracking the secondaries does seem to help reduce the 'dip' in torque that is seen on a dyno graph. I believe this is because there is less turbulence caused when the secondaries opens up. If you assume that a small amount of air is already flowing down the secondary intake runner, there will already be some momentum and when the secondary opens all the way there is less 'lag' before the air begins to start flowing down the tube. It also reduces carbon build-up because there is constantly a small amount of air moving down the tube.
So I think cracking the secondaries is probably good, and I even have a similar effect that I did to my intake manifold when I did all my modifications.

However, your experience and 'cracked secondaries' in NO WAY contradicts the 'theory' and practice that I outlined above.
So don't take it personal.

warmonger

Oh yeah, and one last thing:

How do you know you gained anything from the butt dyno? The but dyno is proven a liar almost every time unless the changes are dramatic. I proved my own but a liar a couple times already.
You will never know unless you dyno before/after...you may just be eating placebos, but at least your happy.

warmonger