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-   -   porting a six port and the sleeves (https://www.rx7club.com/2nd-generation-specific-1986-1992-17/porting-six-port-sleeves-920375/)

Jet-Lee 09-11-10 06:31 PM


Originally Posted by Karack (Post 10210603)
you sure are sounding elitist to me.

we're now getting way off topic of the point of retaining the 5/6th port sleeves to sacrifice low end for top end, there is no need to overthink the simple things.

Retaining the aux sleeves doesn't sacrifice low end, it retains low end. Removing them sacrifices low end for top end.

Perhaps this is why we're arguing?

We may be way off the original topic, but that topic is dead anyways as he already ported his sleeves so we can't really say much. The topic, however, has gotten pretty specific as to whether or not to bridge the aux ports and match the sleeves accordingly. (maybe split the thread?)

I say do it. At least I'm seriously tossing around the thought of doing it myself.

RotaryEvolution 09-11-10 07:02 PM

i referred to the pineapple inserts that the OP mentioned installing which help to supposedly guide the air into the port opening better by adding a "ramp" to the end of the sleeve. perhaps my wording was confusing. this ramp also twists with the sleeve which aims the air at the wrong point in the sleeve(the sleeves don't always sit at the correct 90* angle), it is just snake oil(sorry pineapple).

for bridging the aux ports, i still have mixed feelings about it. if one is going to go that far then they would be far better off taking the bridge out between the secondaries and making true secondary port bridge. the tiny bridge on just the aux ports would have a tendency to disrupt airflow more than help it.

lonetlan 09-11-10 07:26 PM


Originally Posted by Karack (Post 10210775)
i referred to the pineapple inserts that the OP mentioned installing which help to supposedly guide the air into the port opening better by adding a "ramp" to the end of the sleeve. perhaps my wording was confusing. this ramp also twists with the sleeve which aims the air at the wrong point in the sleeve(the sleeves don't always sit at the correct 90* angle), it is just snake oil(sorry pineapple)....

So when the sleeves are not activated(under 3,000RPM), the air is going into the wall instead of out the port. Weren't the 6-ports designed to do that? Please explain.

RotaryEvolution 09-11-10 07:34 PM

insert the sleeves into an iron and then install the LIM onto the iron and open the actuator, you will see that the sleeve usually won't point directly towards the motor or even towards the airflow path of least resistance which is towards the rotor rotating direction. the sleeves generally do not open as much as they should from what i have noticed.

Jet-Lee 09-11-10 10:02 PM


Originally Posted by Karack (Post 10210775)
i referred to the pineapple inserts that the OP mentioned installing which help to supposedly guide the air into the port opening better by adding a "ramp" to the end of the sleeve. perhaps my wording was confusing. this ramp also twists with the sleeve which aims the air at the wrong point in the sleeve(the sleeves don't always sit at the correct 90* angle), it is just snake oil(sorry pineapple).

Ah, ok. It seems like a decent idea, but I'm up in the air on that one. I can see the theory behind it, apparently it's been dyno-proven though?


for bridging the aux ports, i still have mixed feelings about it. if one is going to go that far then they would be far better off taking the bridge out between the secondaries and making true secondary port bridge. the tiny bridge on just the aux ports would have a tendency to disrupt airflow more than help it.
Would be good to try though, none-the-less? I was thinking of maybe taking the aux port slide and instead of removing all the material for the bridge, give it a little (tiny) scoop to help it pull that a/f in during that brief overlap period, but not so much to terribly kill the overall flow to the main port.

RotaryEvolution 09-12-10 12:51 PM

testing is really the only method of proving whether something works or not, bridging the aux ports should either show a noticable improvement in power gains or nothing at all, it's difficult to do conclusive tests though due to the complications involved of dynoing an engine then tearing it down and doing the bridge, retuning and getting the results.

i don't think i've seen anyone do any dyno runs with before and after pulls with the port sleeve inserts either. most people just say they feel the difference but i've also seen people say that slick 50 made their car more powerful, or by switching to synthetic oils, or by using split fire plugs which we all know is BS.

Aaron Cake 09-13-10 10:16 AM


Originally Posted by Jet-Lee (Post 10210549)
Please explain how it's adding overlap in the lower rpm's if the valve is closed.

The overlap I was speaking of was in the high RPM range when the ports open. It would only add a little overlap and port area when you consider the position of the rotor and where a slightly ported secondary port opens.

But you will STILL get overlap when the sleeve is closed, even though it is just a little. The void in the iron between the face and sleeve will allow high pressure exhaust gasses to bypass from the exhaust side of the rotor to the intake side.

This has been tried before, and dyno graphs have shown no real HP increase in the top end. Unfortunately, these graphs were posted years (around 8) ago and I did not save them.

Now, what this can be quite useful for is spooling a turbo, but that's another discussion.


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