Oi there guys. I have been looking to build a 13B 6-port all motor and im looking to make at least 225-250 rwhp. Im wanting to know if having the engine bridged will it really make that much of a difference in the power gains that I will be able to get. This is a S5 engine thats goin into 82 GS RX7. I know about what parts I will need to get the engine into the car and so on and so on. Im talking about the engine, gearbox, fuel & ignition, and rear end. Any HELPFUL input will be noted and greatly appreciated. Cheers guys and thanks.

 

hello?

 

searching is good for your health!

 

i know it is. But all im finding is stuff for 4 ports engines. So thanks for the sarcasm.

 

i dont see you having 250 whp out of a bridgeport. thats alot of na hp. not gonna be streetable id guess

 

Well this car will be daily driven. Ive always gone turbo and called it a day but this build will be pretty special to me. Even if i can pull 200 to the ground ill be happy cause on drag days I can put a 75-100 shot to it for that extra power if i really want too. I just dont want to be seen as another slow RX7. Where I live mate is nothing but mustangs and chevys. And yes 250 rwhp is achievable on a bridgeport. Maybe not from a 4 port engine though, But it can be done.

 

My previous engine was a street ported 6 port out of an 88. I had straight exhaust, 650 RB Holley, RB intake, RB header, Borla Pro XS muffler, stock ignition and got 178HP @ 8500RPM. I can post dyno charts but it'll be next week before I can get them.There was room for improvement for sure but a piece of the coolant passage let go before I was ablt to do so. I think your 200 is attainable but 250 is probably a stretch.

This is the 2nd run, 4th run netted the 178hp.
http://www.youtube.com/watch?v=77SGOjGYHJo

Car now has a halfbridged TII irons, S5 NA rotors, and everything else is from the other engine sans the RB 6 port intake. Still in break in but I'll hit the dyno as soon as it's ready.

 

IMO you are going to have a hard time making that kind of power with any kind of port on a 6-port unless you really have your ducks in a row.

That kind of power level is not something you get accidentally. You either really know what you are doing, or you are paying somebody who really knows what they are doing...

 

Ditto what peejay said! Those are some high #'s for a N/A car.

 

Your right. Thats why I brought it down to a minimum of 200 rwhp. I know 200 is attainable on a 6 port due to the fact that they come out the box with 146ish to the fly, that would equate to like 115-120ish to the ground rough estimate. So I know with a 48 mm weber carb, RB header, 2.5 inch duals all the way to a 3 inch muffler with a good tune on the carb with sufficient fuel will get me to roughly 180-200 rwhp. Lets not forget that im goin to do a full bridgeport on this engine. I was goin to go with a 48 mm pp cut but im not too familiar with pp's as I am with bridgeports.

 

Yeah it is. Thats why I looked at what I do with this car and how much i'll be running this car on the track. I think that 200 at the least will keep me content for the moment.

 

200 at the wheels is still pushing it. You're asking for 100 more horsepower over stock.

Yes, some people have done it. The people with all their ducks in a row.

I don't think a cheap header like the RB unit would help. I forgot where I saw it, but a RB header only picked up 10hp at the wheels over the stock exhaust manifold on an engine that already had some decent things done with it. (I think the difference was 185 vs. 175)

The thing about bridge ports on 6-ports is that some people have found that the aux port closes SO late that a bridge there just results in compression loss to the next chamber. That's why when I did my half bridge 6-port, I only did the main secondaries and left the aux ports alone.

I found some homologation paperwork from the 80's that specified a bridge port for 12A cars, and the bridge eyebrow actually closed before the main port did, and the main port wasn't that high up either. Much less port timing than any 6-port.

If you're starting with a GSL-SE engine, the best bet would be to set the end housings aside and get some 12A ones, and make a four port 13B out of it. While you're at it, use a 12A center housing as well since you won't be needing the fuel injector bungs, and all 6-ports have small primary ports.

 

Well true on that. I have a 12a in my car atm that is VERY strong might I add. I was thinking about using the irons from that block on my 13b but I was told by too many people to just use the 6-port irons and dont touch the aux ports. Idk mate, If im not goin to break 200 all motor with either port setup then ill just drop the whole idea and just keep buying turbos for my rotaries. I just dont get this though. Our engines can (if built correctly) spin sooo high in the revs, But can barely break 200 whp all motor? That boggles me mate. the B16a revs to like 8,6k-8.8k with a 10:1 comp and makes like 160 to the ground stock. I know i just compared circles to triangles but im just saying. :-/

 

My 170whp half-bridge felt a whole lot faster than my 175whp street port. The half bridge had a far more useful powerband, no waiting for the 5500rpm torque spike typical of street ports.

Not really. At least, not for very long. Endurance engines rarely go over 9000rpm, while endurance pushrod V8s are in the five digit range nowadays.

200whp is about 250-260 at the flywheel. That's a lot for a 2.6l engine that throws most of its energy away through the cooling system and out the exhaust.

Keep in mind, this kind of power was average for Ford 2-liter DOHC rally engines... in the late 70's. On carburetors and mechanical ignition. Of course, they could run to 10-11,000rpm and live, and they had the benefit of being able to run higher compression than 9.7:1.

No, no they don't...

And at any rate, rotaries will always make less power than piston engines, it's a fact of life, they just are not as efficient. That is why the motorsports equivalency is usually around 1.7 or 1.8 correction factor instead of the 2.0 that it should be.

And why even a 200hp rotary needs a cooling system sized roughly for a 400hp piston engine, and an exhaust system that needs to be ultra bulletproof and/or wide open lest it be rent asunder by the heat and pressure.

You pays your money and you makes your choices. 170whp was enough to make a fat car with crap gearing and crap tires knock down a timeslip with a 13 in front of it, let's see any Honda with similar limitations do that.

 

b16a's have 160 at the flywheel and 12a irons wont work with the s5 13b housings. All rotaries prior to the s4 rx7 has the coolant orings located in the housings, both 12a and 13b's. s4 and newer have them located in the irons. If you use your 12a irons on s5 housings there will be nothing to seal the coolant jackets.

there are plenty of s4 and s5 6 port N/A motors making 170-180ish at the wheels and more is possible, it just takes the right combo of things. im amidst my own 6 port port/rebuild/swap in my 82, i will be more than happy with 180whp, even 160 is fine by me, still more than enough to have fun with in a first gen

 

there was a guy who dynoed his PP engine, @like 225 rwhp, took it out of the car, and at the flywheel it made 300! at 9k the t2 trans eats a LOT of power!

oh also the honda might rev to 8.8 once or twice, before the valve head pops of and splits the block! we did 165ish with the vtech b18, didn't last very long though....

 

I can tell you that a B20 running at near five figures at full chat is hair-raising. Sounds like an old 2000cc Kit Car like the Clio Maxi.

But yeah, they need building to handle that. I know someone who curses one of the tuner chip houses, because he can't find any good B18 cranks, they're all trashed because the tuner chip d00dz say it's no problem to raise the rev limiter to 8800, then the engine's at the junkyard soon after, and finding an Integra that isn't modded is like trying to find a stock Mustang GT... it doesn't happen. (I know someone who spent a LOT of money returning an Integra GSR to bone stock trim, 'cause he couldn't find a stock one and had to buy a modified one)

 

You pays your money and you makes your choices. 170whp was enough to make a fat car with crap gearing and crap tires knock down a timeslip with a 13 in front of it, let's see any Honda with similar limitations do that.

Ive heard of that being true and have seen it as well. But What im saying is if the most that i can get out of my car is low to mid 13s then ill just keep saving and get a stock turbo swap and whatever else I will need for it and call it a day. I know I know, I mentioned that this car will be daily driven and what not so 170-185 should be more than sufficient. I guess that im just soo used to the feel of turbo rotaries that anything less than what im used to is slow. :-/ I just want to make this car a nice all motor competition for when i go to the track and maybe when im dickin around with a mustang or chevy on my way to work ya get me. Its not goin to be full drag or anything because this car has to keep going while im working on my turbo'd 86. That one my friend will be my " street bish". Lol!

P.S. Youlot have a kind way of slapping people with reality too. xD

 

Lmao! Fa true mate. B20s are scary either way. The walls on those blocks are too thin for my liking. My Eg coupe has a D16y8 in it right now because my girl drives it. As far as stock hondas/acuras go, you can find them left and right here. But RX7's get abused sooo badly hear its tear jerking almost. Ive only seen like 4 on the road where i live because people just beat the ish outta them and send them off to the bone yard.

 

Thank you for enlightening me mate. I forgot all about the interchangability of the irons and housings. :-/ Goes to show how long ive been riding hondas. <<< fail

 

I've seen and worked on enough 9 second sleepers to never think my car is faster than anything... you know that there are new 5.0 Mustangs in the 10s with little more than a tune, headers, and slicks? The factory tune is quite conservative... the factory power rating is conservative, too, as some people have been seeing near 400whp from a "412hp" engine.

 

That is true mate. But your talking about a V8 with 3.7 litres more displacement than our engines. Im only reason i want to do an all motor build is because ive never done one on a rotary. My builds have always been turbo. I'd like to use a little nitro on this block because i know that just on the power that ill be netting off of the build alone i wont be really doing too much damage to most of the guys in the scene here. I know you said that you broke into the 13s while not at your best, was this all motor power or nitro'd?

 

skip the 6 ports, and just go P port, they make nice low rpm power, and if you get the exhaust right, it'll be in the 12's....

 

That is true bro. Dont PP's run hot on the road though? Im not too familiar with them and I dont have a reputable builder that can cut them for me here. But I know that i can get into the 12's easily with those ports and the right intake & exhaust. How long would a PP block last daily'd anyways?

 

i don't have a ton of road miles on mine, just because i'd need to smog it, but so far if anything on the street it runs cold, when i step on the gas it runs hot, but my radiator is from 1984 too....

i think if you DD and didn't rev it to 9k on every shift, with carbon apexes i think it would do like 30-40k, which is a lot longer than you're going to want to drive it, its FUN but kind of intense