GN1's ported or not

[Race Jace]

I am not saying that the porting that champion does is no good. They can port their own heads better than most any one else. I am saying that for some reason having heads that flowed considerably more did not seem to help. Why? that is a good question. Can you fill the cylinder completely with as cast heads and flowing more air doesn't help? Is the manifold runner size restricting the amount the cylinder can flow? I really don't know what is happening.

 

[TURBOGTA1]

I did not really see a gain going from unported GN1s to fully race ported set. the car just never picked up.

If you are not racing a class then the best bang for the buck would be to go with the unported 14 bolt GN1s and scorpoin rockers and run their intake. instead of a stocker. you could purchase all of this for just one set of ported GN1s

Jason, you have the ported version on your car now, did you run the unported version prior !!!!! I was told that with my combo, I could see 35+ H.P with the ported version vs the unported version.

 

[Race Jace]

yes i had the unported versions when i was the first TSM car to go into the 9's way back in 2002

 

[49-blues]

Who sells the scorpions for $300?

 

[Race Jace]

Who sells the scorpions for $300?

I think they are less than that, you get them from anyone that sells the champion heads and also direct from champion

 

[Kip]

Jason, did you recam your car when you ported your heads? My guess would be that you did not and that is why you saw no gain. You have to remember it is all about combo and the cam for one set of heads is not always the best for another set of heads.
Take care, Kip

 

[Race Jace]

I do have a small comp 218 in there.

 

[VadersV6]

Just because a head flows a bigger number, doesnt mean it will perform better. The peak number at .500 or .600 is meaningless. Add up the flow numbers from .100 up to .600, then divide by 6. Or, go in .050' increments and divide by 12. That average number is the only thing that matters. If the guy running the flow bench can block a small spot in the valve pocket with clay, and the head still flows the same number, then those heads have velocity issues. flow numbers are only part of the mystery. If the old turbo and cylinder head were complimenting each other well before, the new turbo may become a bottleneck with some mondo race heads.
Also, if you're filling the cylinders more, but then turning around and bleeding off a bunch of that air back into the intake, with a cam that closes the intake valve too late after bottom dead center, then there is no way a huge flowing head will help you. It starts to become a dance of, get more air in the cylinder, and keep it there.

 

[Blown&Injected]

And the flow at .600 is totally useless if the valve never even gets there. An average number gives equal weight to all the numbers and as I recall the aftermarket heads did a better job than my ported stock irons at the lower ranges and the valve spends much more time there than at other higher lifts. While the lower numbers at lower lifts would drag down the average flow numbers making for a slightly more accurate number for comparison purposes, the cam profile should be considered, as mentioned above, to know what the heads will actually flow. A roller will spend much more time at the higher lifts than a flat tappet cam. It is not a linear equation.