94t66rx7

So I ordered some porting templates the other day from racinbeat for my spare 13BREW that I am going to rebuild and port myself. If you'll notice they don't offer any intake templates for these, so I asked why. They said they have yet to see any performance gains from intake porting on those engines, that the ports are already big enough. Now mind you, the engine on my car right now has monster ports, and while I have great top end power my bottom end flat out sucks, which if any of you drive in traffic know what a pain in the *** it can be so it got me wondering.... my turbo (T66BB) can produce plenty of boost and still be very efficient, so why not just raise the boost to make more power and retain streetablility? I can see why the exhaust needs porting, but when you are running a big turbo why the need for such big intake ports? If you need more air in the chamber what's wrong with just cranking up the boost? I know I may get flamed here, but this is coming from Racingbeat, not from me and I really want to know. Can someone explain this to me?

Cosmo Donk

Good question



The only thing I can say for sure is that at some point you will not be able to push in enough air for the big HP because the ports will be too small. Also, if you can get the same amount of air in at 8psi with big ports than, say, 12psi with small ports, the lower psi will be better because it won't heat the air as much.



Personally I think their comment is a little goofy because the Cosmo ports are pretty darn big and they came before the FD engine. Maybe they compensated with a tad smaller turbo to get some torque but I think if you matched the turbo well it should work fine with a good port job. Also, I have seen that there is more to porting than just opening up the ports. Smoothing, and shaping helps a lot as well. Oh, and maybe your current monster ports are just a little too big

BigTurbo74

really i thought your low end is only noticable affected with a birdgeport....anyway you say that 8psi would be better than the 12 in your example. assuming the exhaust ports were same size, would the size of the intake ports (one ported and other not) make a significant difference in lag? sorry kinda off topic but it got me thinkin........

knonfs

Take this as you will....



I purchase a RB street port template for a 13BT FC, when the fun strated, I was puzzle on how to tport the center plate. Since there is a SIGNIFICANT port size difference between the primaries and the secondaries.



Well their responses was, go down...PLEASE port the primaries per the template....



The outcome:



I hit the water jacket.....on top of that, reputable engine builders have told me NOT to port down on the primaries!!



OK enough

Cosmo Donk

One port being a different size than the other port? Then you would have some goofy rotor power differences I haven't ported anything so I am just going on what I have read and what makes sense



Yah, when porting you have to watch out where you go. I have a blown center plate that maybe I can measure and cut open for people to see so they know how far they can go

mazdadrifter

their car that flipped on the saltflats was a triple turboed 3 rotor - periphrial ported. (tell me they didnt' have a smile on their face the whole time they were puttin that beast together)



I wonder why they periphrial ported it, if there wouldn't be much gain it hp, or maybe it's the high rpm performance that they needed?? (considering they were trying to set a top speed record).

Cosmo Donk

I am sure they needed all of the air flow they could get, along with high RPM power. I doubt they gave a shat about low end with that car

Node

especially considering that those cars are towed to a certain speed.

just start at an rpm where you have some power when they let ya go

mazdadrifter

damn, I didn't know that

andynogo

From what I understand, the smaller ports in the centre plate are to allow for higher intake velocities at lower revs increasing torque down low.



And yeah, NEVER go down on the intake ports on a REW! (But up is GOOD )