right now im streetporting my 12a but have a couple ?s

1. how will a streetported 12a run with 100% stock carb and emissions? will the jets need to be changed? and if so what jets have you guys used?
2. will the stock GS fuel pump be sufficient or will i need to swap a se pump in?
3. is there anything else i should be changing over from my car being 100% stock besides the port job? if so please explain.


thanks guys this is my first rotary build and i know the ?s probably seem dumb but its a learing experience lol and man it is a whole different world than doing sbc or sbf builds haha

 

also i was wondering with the streetport done what kind of power increase should i expect? and what are the pros and cons to how she runs afterward? i.e mpgs? power band changes? rpm increase/decrease? driveability? stuff like that and dont be afraid to get into detail....thanks in advance guys

 

It should run OK with the stock carb and intake. You will not see appreciable gains at all until you upgrade your exhaust.

If you upgrade your exhaust (headder/free flowing exhaust), you should see 155-160 HP with a good flowing stock style carb.

 

interesting, so what i have now is the stock manifold, stock pre-cats, stock cat, then straight piped to the back from the cat...so your saying adding a header would help the port do its job better? 55-60 hp gainfrom a port? thats a 55-60% gain, awesome it will be very noticable if i actually get those number thanks, do u know anything about the other ?s

 

+1 go hard or go go home bro. I street ported my 12a and ran a rebuilt Nikki and pacesetter header. I was happy but after a few weeks I was bored. Currently Im porting my 12a with a Judge Ito Monster SP, Sterling Carb, RB Exhaust and Gilmer pulleys. It adds up quick just save up and hunt down used parts you'll be alot happier. Goodluck

 

any given port job needs all supporting mods like carb/jetting and free-er flowing exhaust to get the maximum gains out of that port job. the better it inhales, it also needs to exhale just as well. if ur limited on funds i'd also do the exhaust. that way id DOES exhale better. then when ur funds allow u can upgrade the carb. g/l with the build.

 

lol no im not low on funds ive been saving for this project all summer, i just have never done this before. i need to know what jets have you guys used in the nikki carbs, what fuel pumps you have used. basicly what setup makes a streetport perform perfectly?

 

I disagree, If you have certain goals, a basic streetport is great. You get a very decent increase in performance, and maintain good driveability, and fuel mileage. If you want a monster port, you have to give some things up. Maybe this guys is not wanting to do that.

But yeah, you will absolutely get the best difference with carb and exhaust work.

 

ya see i like stock cars, im that kinda guy lol i want my port to work like it should but keep the enginebay as stock looking as possible because i go to a lot of car shows and original gets the points.. ill be playing around with my nikki on jet sizes and what not but if someone out there has one jet size that works miracles for them or a certain carb setup that they swear by id liek to know, it could possible make my experimentation a little easier

thanks

 

You will absolutely need to replace your pump with a Carter 7lb pump or similar Holley/Mallory/whathaveyou. The stock pump is barely adequate for the stock engine, nevermind a modified one. You can not use the SE pump. It's pressure is rated for injection, not carburetion and it will overfill the carb. You must use a low pressure carb specific unit.

The stock exhaust is restrictive at best. Replace the whole thing with a decent aftermarket header and at least mandrel bend piping with a couple Magnaflow's in there.

If you want to retain stock appearance and driveability while increasing power, the Sterling is the way to go. www.sterlingmetalworks.com. Tons of info there and you won't be disappointed.

You probably will have to go up with the jet sizes, but I can't tell you how big to go. Join the forum on sterlingmetalworks and Sterling can help you out with that there.

 

 

thanks for the info! great site....ok back on subject, so the stock GS pump puts out what PSI? anyone know?

 

teh sterling nikki is very interesting....with mechanical secondaries it seems like a nice shot plus is about the same price as a rb holley

 

I am using the stock fuel pump (~3 psi) and stock carb with RB road race header and long primary exhaust. Street ported 12A has been in the car for 30,000 miles. A Sterling Nikki is the way to go if you want the stock look, but I would do the exhaust first.

 

Exhaust is the first and best mod to do on any rotary. Stock ones are extremely restrictive to meet noise and pollution requirements. Doing carb or porting mods first is tossing money down the toilet, they cannot reach their full potential without headers and a freer flowing exhaust. Just eliminating the cats and adding headers only is at least a 25 hp gain. A full exhaust upgrade gets you even more.

When working with mods on a rotary, toss out most everything else you've learned modding piston engines. The same rules don't apply.

Rotaries tend to run rich oem. The extra unburnt fuel, along with air injection from the air pump, helps heat up the main cat to clean up emissions. You may not need to change the carb jetting, but Sterling's site will get you set up.

 

ya one thing i did not see on sterlings site....what elevation is he at? because im sure that makes a huge different on jetting the carb

 

The stock carb has an altitude compensator, which usually gets disabled when they're stripped down to the basics.

 

Sterling is in New York. Ask on the forum and he will be able to guide you. He will not be able to tell you exactly what will work for your particular car, every car is different, but he can get you started and with a little trial and error you can get it dialed in.

 

I know my YAW started on a 12A. When it got put on a 12A streetport the jet size went up one, which has also been good on my 74 13B 4port daily driver long time' now.

 

you guys are great help

ok so im in the process of buying a rb header right now from a member, im almost ready to start porting my actual engine, right now im just practicing on spare housings using a micrometer and caliper until my templates come in.

so far this is what the engine setup will look like, and of course ill change things around and play a little bit as i go

1. streetported intake and exhaust

2. engine freshened up with atkins it A (most everything but apex's) i will measure to be sure but ive got a few used sets that are good.

3. RB daul pipe header, going to toss old exhaust and make a full dual set up with 2 mufflers and no cats(most likley magnaflows because ive had good experience with em)

4. stock nikki(for now) with correct jet sizing(whatever i find works nice)

5. (I think but am not sure yet) stock emissions but with deleted air pump

6. pontiac e-fan with adjustable thermo switch

thats it for now, and im thinking saving up for the sterrling nikki is a very smart choice, i would rather have that than some junk holley anyday...time will tell

 

you really should run a collected exhaust setup. You get much more power than running dual pipes all the way. To over simplify it, one exhaust pulse from one rotor passes through and sort of sucks the next one through coming from the other rotor. They call it the bernoulli effect. Fast air over an area creates a low pressure place under the rushing air. sort of like if you have a straw in your drink and blow across the top it will suck the drink up the straw and eventually spray it all over your buddy.

How long the pipes are before they collect determines at what rpm level this happens most effectively (as well as pipe diameter, the angle they converge at and a ton of other variables).

There is a lot to consider when determining this stuff, and I don't have the experience to tell you where the pipes should collect. Others here probably can help more with that. If you search you can find a few good threads on it though.

the racing beat website has a rule of thumb though.

Can't post a link, the site won't let you (at least I dont know how)
Go to the racingbeat website
pick rotary
pick 1st gen
pick "tech tips" from the left-most columb
pick "exhaust systems" from the top
then pick "configurations"

 

ahhh good info makes alot of sense, looks liek with a streetport a collection at 22-25 inches at about 30-40 degrees is ideal which is about the specs of a rb header but im getting the header type with daul outlet so i could make myself a simple collector to go to teh end of the header flange which would put it more at around 25-28" but i think that would be fine...imo

 

Yeah that definitely sounds good. A lot of people have done that type of setup with good results. Sounds like you are going to end up with I really fun car!

 

well thats the coool thing about rx7s im starting with a really fun car and making it really really fun and this is all a learning experience, just like when i built my first chevy 350 truck from a junk beater....to the beauty u see in my sig... but i gotta say learning new stuff about these rotaries and how they work is the most interesting thing ive ever learned

 

My car is street ported and stock carb and stock gas pump,It does have complete RB system Headers to muffler,Got msd blasters coils,msd cables and NGK for ported rotaries br8eix and it is really fun, oh and a k&n Filter ,This little things do make a difference, it moves..is a sleeper very quiet but when i hit it hu what a difference,