so does anybody know what kind of increase in power you get from a street port?

 

Quote from Peejay-You've got it backwards...

Interesting. Here is the quote from Dave on the 2nd page of that thread-

Been there, done that, DOING it right now ---
Big end ports, custom manifold (long runners, MANY hours to fabricate - didn't work), etc etc.
Literally just finished a run (1/2 hour ago) with SHORT primaries, BIG pipe, comp muffler (didn't work quite as well as LONG primaries, but not all that bad)--- there was no hp "curve" just a straight line -- starting at 6000rpm it simply just kept gaining power till I stopped the run at 10,000rpm!!

Oh well, I'll invent some more things to try in the next few days. We are trying to get it to peak about 9-9.5k with as much as possible about 7k.

Btw, this is all with a 52mm Weber IDA downdraft, with 38mm chokes (as E/P carb rules require - it is SO much simpler than the injection).

That last run actually HAD a torque peak -- 7k instead of the 6k we usually see where we start the "pulls". Nice find out about where the torque was.

Dave --

Sounds like he had done it in the past and wrote the page on the website. It also sounds like he has revisited the Siamesed 6 port for his new convertible E-prod. car and has been learning/trying new things.

The power curve from 6K to 10K sounds great for a race car, BUT E-prod is limited to stock internals so he was looking to lower the peak power somemore (9, 9.5K) for longer engine life.

Or is there something I missed?

 

Only use the 4 port motor for the housings and oil pump. Use your n/a internals (rotors). You want the higher compression. Either use a T-II manifold (at first) with a standalone ecu or go Holley. The reason I say at first is because that manifold sucks. I build custom ones and it is easy to outperform that one. I would have to actually try in order to do worse.

After you decide on you motor/porting/intake setup then we can discuss your exhaust setup!

 

Just for a bit of thought here. A few years ago I talked to Paul Yaw on the phone about doing a very unusual 6-port engine. It involved hogging out the outer ports to one giant one. The difference comes from the fact that the intermediate housing ports were going to be completely filled in! Only 2 ports on the engine. This would help give back some much needed intake velocity. That outer port can flow huge amounts anyways. The runners could be almost a full 2" in diameter each. The intake would have resembled a peripheral port engine's. Tuning was going to be done based on runner length using a medium sized plenum and a standalone ecu. Custom exhaust sleeves and a long primary exhaust would have completed the package. Never did it though. The flowbench numbers looked very promising though. I would be curious to see how it would work. Any thoughts?

 

See thats the deal...im not going to go for the 4 port...i dont want to go for a motor swap...but just to say if i was going to take the motor apart anyhow to do the streetporting could in at that point just install rortor housings that were from a four port and effectively have a four port motor??....and just for the guy asking about how much power the streetport makes its actually about a 20 percent increase from what i hear.....

 

You could do that. However, the exhaust sleeves on the T-II housings are better flowing (if you plan to keep the stock ones), the intermediate housing has more material behind the ports. In other words you can port the primaries out larger on a T-II housing than an n/a. Obviously you want the outers so basically all you would use from your old motor is the rotors.

It is very easy to adapt/portmatch the 6-port intake manifold to work with the 4 port motor.

 

Thanks for the info dltrezan i really wanted to find out but nobody seemed to answer. exept yeah my car pulls alot harder now.

 

To make it a four port you need to change the END housings.

You basically ARE doing a motor swap by the way... pull out the old, throw in the new.

 

yo i got it now........this is what i am going to do when i gte the money...looks first, i dont care what anyone says so the corksport kit first with the 99 jspec lights molded in the front running on ADR 17x8.5 both front and rear with the s5 tails in the rear...but as far as motor goes im going to go ahead and buy a jspec 4 port or find another one somewhere else without all the turbo goodies because i know myself and im very likely to get the turbo bug and spend ungodly amounts of money on upgrading everything over and over again, im going NA in a way that way i have a cap.....so ima get the 4 port and streetport it and throw my 6 port rotors in with 3mm apex seals along with all of the exhaust goodies and fuel bolt ons and whatever....then im going to go ahead with the timing retard kit that way when i decide to do my 150 shot NOS wetkit it will run smooth and safe, now i kknow ima get flamed for wanting to use NOS but its going to be on a completely expendable engine considering im keeping my old one, and i will not use it for ****...some people say that but i truly intend that......with all the motor mods my car should be plenty quick for daily driving and knocking ***** out of hondas rustangs and camarios, but just when i have the chick in the car and that one guy pulls up in a vette thinking he is gonna mess with me like im some ricer with a bodykit then he'll have something coming when i hit the button...otherwise no...and ill have one hell of an engine built to handle that big of a shot...so thats it for me....mind made up...thanx guys..........im also going to use the same tranny with 5:10 gears and a differential from a gtu or T2..then ill be set....

 

from what I have been reading you Dont Want 3mm apex seals. For this reason. They wear your rotor housings faster. From what Im told you probable want some 2mm race apex seals they wont chew up your rotor housings and will handle as much power as a n/a could dish out. The 3mm apex seals just hold up to detination a lil bit longer but will fail just the same and the result is much worse. If you watch your a/f you will be just fine if not better off with 2mm seals

 

why dont you just buy a six port thats blown.. 89+.. rebuild it and get rid of the 6 ports.. easy task.. and street port that instead of trying to get a T2 jspec...

I am building my engine with a huge streetport on the primarys and a small bridge on the secondaries.. i wont break the bridge and ill have a reliable fast n/a