Has anyone compiled the rpm the various sizes of streetports make max hp at?

ex: The racing beat streetport templates make max hp at x,xxx rpm?

I'm trying to find streetport templates that make max hp under 8,500rpms. On a 13b 4port with 3b plates and gsl-se rotorhousings.

 

It also depends a lot on the rest of the system (intake and exhaust). Runner size, length, exhaust diameter, type and location of collector, megaphone/no megaphone, etc. all play an important role in locating where the peak power occurs and how tall/wide the peak is.

In short, I would say no to your question. You can piece something together based on what people have done on the dyno, but in most cases there are too many variables to draw solid conclusions (different exhaust, different intake/carb, different tuning, different engine wear levels, etc.). It would be nice to have a data collection like that, but most people can't afford to build a streetport, dyno, then tear down and put in a different streetport, and repeat.

I would just dig around on here for dyno charts, find one with a nice peak below 8500 (should be the case for every streetport), and see what they used in terms of a setup. You typically also want something with a nice and flat torque curve (which gives a linear HP curve) if you are doing autocross/road racing where you will be using a wide RPM range. The larger you go on ports, the more "peaky" they typically become. The peak is taller and usually shifted towards a higher RPM with larger ports.

Again, it all works as a system. A PP engine that peaks at 10k RPM won't work so well if you put on a stock exhaust and somehow adapted a stock intake which are designed for and engine that peaks around 6500 RPM.

 

aaaaah, "ditto", yeah, what he said

 

Agreeing with and adding the above: it's more complicated than just size; pattern type, shape & location of the ports (intake and exhaust) are also influential, if not crucial.

I haven't seen anyone publish even a good rigorous system for exactly describing one port plan from another - - something similar to what's done with cams, for example, where angle and lift are the main factors - - that would make it possible to even really compare two port setups with technical accuracy.

Fact is, I don't think even the idea of "street port" has a technical description beyond "a port that's still conservative enough to be able to drive on the street."

Before we can really compare, we must first be able to identify.

Or am I just missing it somewhere?

 

Again, agreeing with what's already been said.

As far as I know, a streetport is defined as a side port that "stays within the lines" (i.e. no bridge). This tends to imply streetability, but there are streetports with decidedly street-unfriendly powerbands just as there are a number of people who drive bridgies and p-ports daily (heck, there are some peripheral ports with more street-friendly powerbands than some streetports).

 

Yeah, with intake, exhaust, ignition systems being a constant. I see what you guys are saying.

Or even looking for general idea like: The Ito Aggressive Streetport adds this % of hp and torque at high rpms, anoth % at midrange, but you lose this % of hp/torque at lower rpms.

Like what divin diver said for cam specs... I'll check out the dynographs.

 

I am also interested in some different experiences from people with varying port jobs. Judge Ito ports of particular interest.

 

there are WAY too many variables to say what port does what. i don't think ive sever seen a street port peak over 8500, most peak at maybe 7500...

the PP example is actually a good one, they are SUPER picky about the exhaust, streetport less so, but getting the exhaust right is probably more important than one streetport template over another.

 

Yep. The other big factor besides the size/shape of the port is the transitioning between the port and the runner. That is where the real art in porting is. The templates just give you a 2D shape at the surface of the iron. It is up to the porter to make a nice transition between the runners and the port. Because of this, you can have everything else equal (even the porting template), but one engine makes more power than the other because of the transition on the port.

 

on one of the strongest engines ive seen the port opening was opened up to a medium sized template, runners were left alone. new irons/rotors/housings, it did 389rwhp@12psi. if you look, its really close to what aaron cakes car did at the time at the same boost, and he has a bridgeport

 

I think the only way you are going to get an answer to this is to contact the engine builders directly.

 

gotta keep this thread rolling i would ask Lynn E. Hanover on the no pistons forum that guy knows alot hes been racing rotarys a long time. hes in the building/porting section

http://www.nopistons.com/forums/Rota...rting-f81.html

cheers
chris