Yo guys ive got my 86 NA moving back to the Portland area, was thinking of getting it either agressive streetported or midly bridgeported. Now question is what kind of horsepower gains could i be lookin at and what is the difference and what kind of reliability could i be expecting after 20-30k, with all out bolt ons such as headers....high flow cats or none at all....intake, ecu all the goodstuff, i have yet to see a thread that even discusses porting on a tech level to where us new guys even know what to judge...........

Derek Adams
86NA....80k.....aftermarket dent in front fender
Zoom Zoom stickers that are on backwards cuz i put them inside the car...not outside

 

I couldn't tell ya but I would like to know what those even are...I asked a guy I work with (who races a '69 SuperBee that does 11's) and he didn't even know what a bridgeport was...

 

streetporting is good for street car, hence the name, any aftermarket adjustment you make that large or that increases the hp that much will shorten the life of your engine, only go brideport if you have a lot of money and dont care if you pop your engine like 3 times a year, it also all depends on how you drive, i am going pinapple stage 2 street port this winter, with a stage 4 hybrid turbo, after bolt on's i will be happy with the hp.

--joe

 

There is no benefit to bridgeporting a 6 port engine. I've already been there done that. My GSL-SE has a streetport and it will stay that way. The 6 port engines flow like crap compared to a 4 port. I know they can make some decent power and I even know why but I won't get into that. A bridgeport motor likes to be able to breathe very well which the n/a intake and exhaust system do not do. If you went bridgeport on a stock exhaust manifold car you would actually lose power! Go for the streetport.

Go to the kills section and read my post about "My GSL-SE vs. '87 T-II" that should give you an idea on what to expect performance wise.

 

You can't get a big street port on a 6 port either, not enough material.

If you are having the engine done you could go 4 port, or just buy a TII for the same price as a rebuilt NA engine...

 

alright so we have basically established that bridgeporting is not for 6 port engines, so what about an agressive pineapple street port, those guys are in portland where i am going back to anyhow.....but i plan on using an intake manifold from a T2 as well as a T2 fuel rail.....

 

What about a six-port bridge with a holley 650 4barrel and mt true duals? Suck that in your T2 and smoke it!

 

If you use a true dual exhaust on a bridgeport you will lose power. It absolutely has to be a collected system when you have that much port overlap. Dual is only good for stock porting. Tried it several ways and found this to be true. The 6-port end housings just don't flow that well. The runners are so small that there isn't much room for the air to turn at the end. Still wouldn't work as good as a bp 4 port. I do have a friend who has a very special 6 port setup in his tube frame VW drag car. He hogged out the outer ports into one giant port and then added a giant bridge to it. Intermediate housing was as large as it could get too with a big bridge. Exhaust ports had sleeves removed and the ports ground out as physically big as he could get them. Not a very reliable engine but he runs 10's n/a with a 4 barrel Holley. Power band is from 8000-12000 RPM! Oh yeah he used to have a dual exhaust but then changed to a long primary and gained tons of power.

 

Hows he running 12000 rpm on a 13B?

 

His engines don't last more than a few runs. He's got more money than me though so more power to him.

 

Yes, Dave Lemon from Mazdatrix posted on an experiment? just siamesing the 6ports (no bridge- racing rules) and he could not find a peak power at first as it climbed past 10,000 rpm or something. I forget the details, but interesting.

 

so what kind of power increase on a tII
lets make the assumption that the car is stock and nothing really done to it.

 

alright guys great posts, but my point is when i want to dig into the inside of my engine what is the absolute best route for getting alot of power for my NA and keeping it that way rather than going to a T2 swap...i mean i can do it, and im sure it would bring more power..but there is just something about being able to say, "yeah the bastards quick, and its not even a turbo"...kinda makes it a lil more special

 

i hear ya.

 

You've got it backwards...

They tried making it one big port in the endhousings and lost power big-time because there just wasn't any port velocity. I suspect this is why that bridge ported 6-port engine ran so miserably - without good port runner velocity, NO engine will make any decent power, especially one as "pipey" as an engine with lots of overlap.

They found that "there's no ral point to porting the 6-port" because there's already so much port timing that it's pointless to try for more. That's why they couldn't find peak power, the 6-port port timing is already quite radical.

Here's some linkables for those of y'all who like to read and learn, not seek quick distilled sound bite answers.

https://www.rx7club.com/forum/showth...highlight=port (see 2nd page for the Mazdatrix E/Production reference)

https://www.rx7club.com/forum/showth...ht=port+bridge Info on bridge ported 6-port engines

https://www.rx7club.com/forum/showth...highlight=port (recent discussion peripheral port engines, which turned into the usual street vs. bridge pissing match... but still, some good info)

 

i dont think the t2 intake maniflod will fit on a n/a, and there is no diff between the t2 fuel rail and the n/a except for the injectors it holds.

-joe

 

The T-II manifold will physically bolt up but you 've got some serious port matching to do.

 

If you want to stay NA and have real power, your only option at this moment is to go with a 4 port 13B. I am sure you can use the 4 ports end plates, and T2 lower\upper inatake manifolds, and the stock ecu.

Now that lead us to the next problem, you won't get that much HP with the stock ECU\AFM.

Now I know must people in here are tired of hearing me say this, but I've seen some wicked fast 4ports, carburated 13B's!!

My opninion, rebuild a T2 engine (street ported), put it in with the stock ECU, and get a stand alone later on. This otions opens up a lot of doors for the future

 

yeah, and you are going to want the TII rotor housings when you go to do your exhaust porting because from all accounts i've heard, it's hard as hell to get the NA diffusers out of the NA housings. You'll end up saving yourself a lot of time and trouble, and if you follow KNONFS' design, you will be able to clean out a lot of crap from your engine bay (going carb 13B 4-port).

 

Good good....so we are getting somewhere here......and about the intake manifold fitting on the 86NA it will...i saw one a few days ago..guy has it on his vert...but it takes some grinding down and some matching, wasnt really easy but not too hard....so now, some progress....so best thing i have heard so far to do is to swap to a 4 port.....say for example getting a jspec from corksport.com....i think they want 900...but im almost sure that includes the turbo and ecu and all the other goodies..might as well do the turbo swap at that point...but dammit i want a quick NA and am willing to go a lil further just make sure it stays that way, gotta be a lil unique, nothing like telling some guy in Trans-am you whooped his 350 WITHOUT a turbo......that will get some attention...a 79 CU motor vs. a 350....that will make him shake his head.......plus i have a bit of a problem with turbo's and that is the constant want for something bigger and better..........im like the kid at the toy store.......i get and exhaust and all the lil goodies...ima want a bigger turbo, then ill need a bigger intercooler to go with it, then a bigger and more expensive BOV, wastegate downpipe, ECU bigger injectors.....then ima get bored.....want another turbo...bigger intercooler...and so on.....by that time might as well have bought an FD....im not the type of person that can by the Gi Joe and not get the whole base and upgrade everytime something a lil better comes out. SOOOOO KNONFS basically if i could find a jspec 4 port with al the goodies no turbo set up maybe around $600?????? then run a carb after streetporting along with all other bolt on goodie headers, no cats, intake....or standalone.....how much horse u think is possible?? Im just trying to establish the best possible way to go for all of our NA buddies up in here who want to get the best for their cars.....thanx....

 

So we agree than you will make more power out of a 4 port?

Get a jspec, sell the parts you don't need, sell the parts from your current engine that you won't be using and get a Microtech MTX8 (cheaper than the halltech).

You will extract more power out of a stand alone ecu, rather than from a carb. How much power you'll be able to extract?

Hard to say, I've seen a 14.6 seconds out of a carb 6 port, and I've seen low 13's out first gen with 4ports engine.

I would expect high\mid 13's. Actually there is a video around here, there is a 2nd gen NA with a ported RE 13B, auto tranny, running 14.0 @ 100MPH. The guy who took the video, said that the driver mentione having problems with the car, and that the car has turned 13 seconds pass........

 

yeah so what kind of power increase do you make off streetporting an engine?

or is there no increase at all?

 

aight guys for us lil NA's who want something to do....we have gotten down to getting a Jspec 4 port....street porting it agressively.......all the normal bolt on goodies.......now....carb or stand alone...im just trying to get a basic standard goal for us weak six port NA guys to look to with out going the turbo route.....i mean hell it sounds good to me.....jspec 4 port 600.....sell the stock motor.....3mm apex seals a few hundred, aggressive streetport, i dont know how much that costs...exhaust goodies and intake....then carb? how many horses at the fly u think if we got the cats and get rid of the EGR?....just trying to set a standard here...thanx guy..been alot of help

 

do like me... 87 13b 4 port half bridged.. racing beat intake and a holley 650 wit no cats and full racing beat exhaust some sticky tires.. a gxl diff... and ull be straight... i havent had any major problems 4 port with a holley is the way to go for bridge.. idles around 1000-1200 rpm... the high end is just as incredible and even better than a turbo II with little mods... runs 13.8 @ 111 mph and it aint my daily driver.. my 91 na is... but it still kicks *** and is very streetable in my opinion..

 

damn sounds great to me...how much does all of this cost and would it be better for reliability to just get an aggressive street port?..thanx