nick812

Can someone please explain this port job better to me? I tried to do some research but everything that came up was the full Pport. I am thinking about doing a Semi-PPort 13B for my 85 GS.

Lynn E. Hanover

Well, you were not supposed to know about this, because only really sick people would do this to a rotary.

But, if yoou promis not to do it, I will tell you how to do it.



First in the quest for more power you add the standard bridgeport. Then you get outrun a few times, and you go back in and do a big "J" Bridgeport, and that seems to work great, and one day a guy with a Pport engine outruns you, so you check on the price of some Pport housings. You wet your pants when you hear that price.



But the engine is apart already, so what to do?



Suppose that the "J" bridge port could be made bigger? The first problem would be that you would strike water. So we fill the whole water jacket next to the port with an aluminum filled epoxy. If there is no water there can be no water leaks can there?



So now you can use the epoxy as on wall of the runner and cut the housing part of the port further to the centerline of the housing, and the port is just huge. So you reassemble your new killer engine and go racing. You find that the added port volume has dropped your runner velocity so low that the engine only comes on hard above 8,000 RPM. Fun when you can get that far, but a general pig to drive in traffic.



So you take it apart again and make the port even bigger, but then fill in most of the side ports with a steel or iron filled epoxy and reshape the port to look like two small Pports side by side.



Now it drives pretty well, and the power comes on hard at 6,000 RPM. Now the guy with the factory Pport still outruns you but just by a hair, and when you show him your engine, it looks like a side port.



The down side beside the down time and porting is that it has to have solid one piece apex seals. Metal, carbon or ceramic, but one piece. There is no way to keep the end piece from falling into the Pport opening.



If you go to this port style first, and keep the closing line closer to stock, street driving is much improved. If turbocharged, it acts like a turbo Pport, yet better low speed drivability.



Compression seal grooves must be blocked next to the port as in the "J" bridge port.



Lynn E. Hanover

Lynn E. Hanover

Well, you were not supposed to know about this, because only really sick people would do this to a rotary.

But, if yoou promis not to do it, I will tell you how to do it.



First in the quest for more power you add the standard bridgeport. Then you get outrun a few times, and you go back in and do a big "J" Bridgeport, and that seems to work great, and one day a guy with a Pport engine outruns you, so you check on the price of some Pport housings. You wet your pants when you hear that price.



But the engine is apart already, so what to do?



Suppose that the "J" bridge port could be made bigger? The first problem would be that you would strike water. So we fill the whole water jacket next to the port with an aluminum filled epoxy. If there is no water there can be no water leaks can there?



So now you can use the epoxy as on wall of the runner and cut the housing part of the port further to the centerline of the housing, and the port is just huge. So you reassemble your new killer engine and go racing. You find that the added port volume has dropped your runner velocity so low that the engine only comes on hard above 8,000 RPM. Fun when you can get that far, but a general pig to drive in traffic.



So you take it apart again and make the port even bigger, but then fill in most of the side ports with a steel or iron filled epoxy and reshape the port to look like two small Pports side by side.



Now it drives pretty well, and the power comes on hard at 6,000 RPM. Now the guy with the factory Pport still outruns you but just by a hair, and when you show him your engine, it looks like a side port.



The down side beside the down time and porting is that it has to have solid one piece apex seals. Metal, carbon or ceramic, but one piece. There is no way to keep the end piece from falling into the Pport opening.



If you go to this port style first, and keep the closing line closer to stock, street driving is much improved. If turbocharged, it acts like a turbo Pport, yet better low speed drivability.



Compression seal grooves must be blocked next to the port as in the "J" bridge port.



Lynn E. Hanover

13BTNOS

Mr. Hanover,

I think he was thinking more in the lines of this port.

Lynn E. Hanover

Nothing "Semi" about that. It is a tiny Pport.



Lynn E. Hanover

rotaryinspired

Lynn



Do you have any pictures of what you are describing. I think my mind pictures it correctly, but nothing like seeing the real thing. Thank you in advance.

Brad

BLUE TII

The "semi p-port" Mr Hannover is describing is a bridgeport that has been extended very far into the rotor housing, but still uses the sideports inlet.



To imagine this using the picture above- delete the little round peripheral port in the rotor housing from the picture entirely, extend the bridge port (the one that is cut into both the rotor and side housing) toward where the little round peripheral port was and finally fill in some of that stock side port (the one entirely cut into the side housing).



The port pictured is a variation of a type refered to as a "cross port" in Japanese and was first used by Mazda in their very first rotary car the Cosmo Sport, but abandoned in the production versions.



The cross port is still very popular in Japan! I was looking through a Japanese RX-7 magazine and there were many companies selling manifolds and rotor housings in several variations and combinations to convert to cross port.



Some used the Mazda Factory peripheral port rotor housings and custom cast lower intake manifold to convert to stock primary port, peripheral secondary port and a blocked off stock secondary side port.



Others used a custom peripheral port rotor housing (very much like the one pictured) and a custom lower intake manifold so that the stock primary and secondary sideports were used as well as the new small peripheral port. This combination looked stock to all but the keenest eyes.

racerguy180

I agree with Blue TII, I remember reading an old HyperRev RX-7 Magazine that had the "cross port" in it.

I think the old Scoot Time Attack car had the hybrid peripheral/side intake port combo.



I will try to find it and post a picture of it.



Erik



Lynn: I am amazed at the amount of knowledge that you bestow on us!

Lynn E. Hanover

I have no such pictures, however I can draw up one in MS Paint.





Lynn E. Hanover

13BTNOS

That port work is what most people call a "semi-Pport". Almost all the low seven second cars from Puerto Rico are running that port. It is a tiny Pport but you have to remember that all the side ports are also utilized and as with that picture the side ports are also bridgeported. This style of porting combined with a Borg Warner S400 80mm turbo are producing well close to 1000rwhp. http://www.ausrotary.com/viewtopic.php?t=46604 If you follow this link and look at the top 10 worlds fastest 13b powered cars almost all those in that list are running a "semi-Pport". Out of the top ten list only one car is not from Puerto Rico and that would be Abel Ibarra. Here some shots of the semi-Pport manifold.