89_Rx-7_GTUs

I was wondering i have not seen a thread talking about what power and RPM band the different ports give you!(PP, brigde, street )i would appreciate it thanks!

89_Rx-7_GTUs

what RPM range would i expect after afull street port?

micah

Why would your RPM range change?

boostedfc3s

iTrader: (2)

I think he means power band. At what RPM would the power band be for the different types of porting.
From what I understand is that the more radical the port the higher the power band is in the RPM range. Please correct me if I'm wrong though.

micah

Ahh. I guess that makes more sense.

classicauto

iTrader: (3)

Yup, thats the idea.

Any porting you do will remove power from the low rev range, although there's nothing fun down there on these engines anyways. And the further you take the porting (larger street--> half bridge---> full bridge--> semiPP--> full PP) the later the power comes on.....basic rule of thumb. There's obviously intricacies and situations that are exceptions, but thats the general rule.

There is no "list" because every port is different. They can't really be quantified into an "X port gives X power band" statement because the ports themselves as well as overall setup varies so greatly on each application.

89_Rx-7_GTUs

That helps clear things up thanks!

MmSadda

iTrader: (2)

You should still redline at the same place, but might hit peak power about 200rpms after where you would have before.

89_Rx-7_GTUs

Thanks that is more ike the answer i wanted!!, any idea about PP port? So my ? is what is the main way to gain RPMs on these cars besides porting?

classicauto

iTrader: (3)

Actually I think you misunderstood the prior response.

Engine's don't typically make peak power at redline. The example mmmsada is giving would be as follows.
(purely example don't quote actual numbers)
Stock port makes peak power at 6500rpm
Street port makes peak power at 6700rpm

Neither setup redlines until 8K since I'm using an S5 N/A in the example.



The only way to safely increase the redline is balancing and clearancing your internals. Clearance the rotor tips so the don't contact side plates, even a treated e-shaft would be worth while to reduce flex.

But at that point, you get into an entirely new ballgame. In order to turn ~10,000RPM you'll need a flywheel and clutch rated for it (unless you don't value having legs/feet) as well as a scatter shield technically. And to top all of this off, your stock intake manifold isn't well suited to run those revs. I mean, to do a p-port at all you need a custom intake, but even a high revving bridgey should have something suited for the high RPM flow in order to benefit from having the capability to rev that high.

ericgrau

iTrader: (1)

Porting doesn't increase the redline. But it does decrease low rpm power and increase high rpm power. So it's often helpful to combine a port with a high redline. A street port just means enlarging the stock ports a little, so not much changes. A bridge port adds a new port next to and outside the stock port. A peripheral port gets rid of the stock port and puts the port on the apex (not on the side like stock). A peripheral port is often combined with a 12000rpm redline. Among other things you need a custom made intake manifold for a peripheral port since the port moves ($$$). A street port OTOH doesn't need anything special. A BP or PP also has a high idle, poor mpg and poor emissions due to the lousy low ends. A street/stock port only loses a little mpg and emissions, and the low end is still fairly decent. That's why the stock port is where it is, and newer rotary cars merely increase the port size.