I am planning to pull the motor out of my 85 GSL this weekend. After I've pulled it and torn it down, a friend of mine who does a lot of work on RX-7s is going to rebuild and port it for me and reinstall it when done (all for $500, is that a good deal, he's really good with the damn things, got a second gen he pretty much built from scrap that runs high 12s no problem). This is my only car and gets driven a good bit, should I get streetport or bridgeport? What other mods will I need to get maximum performance out of either of these options?

 

A bridge-port will need a good intake(read 48 IDA Weber or fuel injection) and a very free flowing exhaust to make maximum power. With a street port you can run other intakes and still have a relatively quiet exhaust. Also, the bridge-port will idle at about 1800rpm and fuel consumption is awful. That being said, if I could go back and get a bridge instead of a street-port I would as the power available from a street-port gets boring fairly quickly.

 

Well, the damn thing has been idling at 2000 for the past few weeks, (can't find vacuum leak, may have something to do with blown apex seal(s)), so I'm used to that. To be honest I like a slightly higher idle, gives it a nice purrrrr. But is the fuel consumption so much more all the time or only when I lay down on the gas? Also, will a bridgeported engine run off the stock carb for a while until I get a new carb or get the chance to bore and re-jet mine?

 

PS- I have already ordered an exhaust cutout that will be welded either in front of or behind the cat, will that provide sufficient flow, or will I still need a higher flow header?

 

I assume it will run with the stock carb but it will be very lean unless you re-jet it. But, even if you bore the stock carb it will not flow enough to make maximum power on a bridge-port.

 

Yes, everyone, I realize exactly how loud this coutout will make the car. THAT'S WHY I WANT IT. I pull a little valve control mounted somewhere in the cabin, and I'm running on the stock exhaust, with a prettier muffler of course. But when I want pure performance, I open it up. A friend of mine has one on his Rex and the other day, some kid in a Civic pulls up and starts revving his engine like he's got something. My friend opens the cutout and pops it up to 7500. I swear small children 5 miles away wet their pants! You should've seen the look on the little rice-burner kid's face. Needless to say, he was horribly, horribly put in his place!

 

I am a little lost. What is this "cutout"?
Details.
Pics.

 

It is a y-shaped pipe that mounts anywhere on the exhaust piping (post or pre-cat) by being welded in. The single end is the collector piece (faces front of car). One of the ends of the "y" is welded to the rest of the exhaust piping. The other end is left open. It has an adjustable valve that can be closed to restrict the exhaust to the stock system, or opened to cut it out right there. Basically, its a way of being able to select between streetable or full off-road exhaust that can be controlled from inside the car. You can find it at the JCWhitney webpage under their universal exhaust heading. Fits all pipes 1-5/8" to 2-1/2" diameter and costs $21.95 plus however much MIG welding costs (about $50). Not a bad way to go if you ask me!

 

The only problem is, especially on a rotary, going with an open exhaust makes the mixture VERY lean. So if you do this, you either have to tune the carb for either full exhaust or no exhaust, and it will run like crap the other way.

That's why I'm thinking about NOT running a dump pipe this racing season... it was extremely cool, but it was a tuning nightmare.

 

Bridge!!!
BRAP!!!! BRAP!!!! BRAP!!!! BRAP!!!!

 

You don't need a bridge to have a brap-happy idle... my small streetport idled nice and brappy When I turn it into a big streetport (I checked - there's not enough metal to bridge the housings safely ) the overlap will be increased even more...

check out the new Mazdatrix video... this is their 6-port streetport engine for their E/Production racer... you can read about the engine here https://www.rx7club.com/forum/showth...5&pagenumber=2

link to video is here : http://www.mazdatrix.com/faq/epconv.htm

very sweet

 

My extend port(street port) never had a brapy idle the power was ok but i soon got bored of it hey REVHED. Then i got it bridgeported the power is so much better then the extend port but the power doesnt start to come on till a about 4.5k and really gets going a 5K. To get the most out of bridgey injection or a ida weber is your best bet but im running a moded nikki from an rx2 and it goes pretty good. Raced wy friends turbo, auto silvia(240sx i think) and killed him of the line then had to back off as we came to another red light and i was about 2 car lenghts in front of him

*added bit*
But im sick off my car now had it for over 3 years. in few months im goin to buy a T2 dont know what year model yet.

 

header dump in the v8 world

at least thats what i think hes talking about



id go street port,
bridge port is kinda wild for a daily driver,
you have to remember you lose low end torque with a bigger port,

that why those people with huge ports when they race have to rev to 5,000 to get the thing to go.

i think its all in the rb tek manual

 

How many people have actually experienced a rotary with no exhaust after the header - it aint bearable at 3k much less 7.5k

While making my own exhaust I drove the car around the block with only the header on - I didnt get over 3k for fear of going deaf! Another time I had to drive my car home from a race with no muffler - two straight pipes that collect right before the axle into a single - I had to stop at a gas station to stick tissue in my ears because it actually hurt to drive down the freeway. Your car may not be as bad - mine is bare inside, but it will still be very loud. Plus the powerband will shift dramatically with a dramatic change in the exhaust configuration.

 

I used to race with open header.

It was cool

 

sounds like we were once in the same boat,
i once had to drive home after breaking my exhaust right after the header,
man was it ever loud
if you went over 3,000 you were just asking for trouble.
cops would hear you from an easy mile away

also once had it break right at the rear axle,
that wasnt quite as bad,drove it like that for about 3 days.
no freeway though.

my car is also gutted in the inside

 

your right in ohio,we should meet up this summer and go down to mike p's to help with his engine swap.

 

earplugs under the helmut?

 

Your open header won't be as loud in the cabin if you pipe it all the way to were the stock tip hole by the bumper. I have run a open header with a fully open custom pipe to were the muffler was this way and it really makes a difference! If the pipe ends while under the car, the sound waves bounce right off the ground back at the car making it very loud indeed as you know.

 

I think it depends on what you want to do with the car. BUT, for that price, I'd sure as hell go for it!

 

I would but it's too far for me right now.

 

Once you've gone to bridgeport, can you add forced induction? I want to bridgeport my 12A, but I also eventually want a supercharger. Is supercharging something better done to a streetported motor?

 

Go with a turbo instead...

 

Either way, can forced induction work well with a bridgeport? Or is it better done to a streetported motor?