Instead of pistons, porting may be the best solution for you. Since it's a recent rebuild, you won't need apex seals or any other hard seals. If it doesn't smoke, you won't even need oil O rings. Don't even bother cleaning the rotor faces since they'll just get covered in carbon again anyway.

All you'll need is a gsket set from Mazdatrix (around a hundred bucks) and a Dremel with the bits of your choice (I prefer cutting disks and sanding drum myself). Oh, don't forget a porting template.

I built an engine for a friend last year which he then overheated. All it required to fix it was a quick teardown, a gasket set ($100), a little cleanup of the existing streetports (I made 'em a little bigger than before, hehe) a set of used rotor housings with identical chrome wear to the old ones (another $100) and some exhaust porting. I didn't even clean up the rotors. It went back together fine and is now my daily driver. It's nearly ready for its 2nd oil change. Only $200 and I have a great little engine. Maybe you shouldn't give up on your rotors so quickly?

 

how much difference will the porting make? and since my compression is low, wont I need to change apex seals while I'm in there?

 

It's possible. It depends on the wear and condition of the apex springs. You'll also be able to check for missing chrome.

22k might be enough to replace the apex seals. Or not. It depends on your budget. Some will say that since you're rebuilding the engine, you might as well go all-out and replace everything. Heh, sure. They make it seem like the act of R&Ring a rotary engine is some huge monsterous job or something.

The thing that you need to remember is that it's already a running engine. It'll still run even if you don't replace anything other than the basic gasket set (assuming it goes back together correctly, which isn't hard with an FSM or Haynes manual to follow).

How much do you have to spend?

 

currently I have no budget, so its a scrape together money kinda thing

 

crazy question, but is there any way to port one without disassembling? anyway to "stuff" anything inside to keep the shaving from getting in the engine?

never mind, I just read some more about porting, didnt know it was done to the INSIDE of the rotor housing until just now, so the answer to my question was an obvious no

 

uhm... no... refer to my post a little down the page for my SE engine's ports to see why you can't do anything liek that without disassembling... u'll see

 

You could stuff something into the ports and sorta dig around with a porting tool of some sort and hope metal shavings don't find there way into the seal slots on the rotors and stuff. Honestly, I think everyone has thought about this. Trust me when I say that it is so much better of an idea to port the engine when it's apart.

If you could scrape together the cost of a gasket set for your year of engine and have faith that the apex seals etc are going to survive a teardown and rebuild (I'm sure they would, but anyway), then you could probably get away with spending just a little over a hundred bucks. You'll need new coolant afterall. (unless you like to reuse it for some sick perverted reason hehe).

I like to use Vasoline as an assembly lube. Some always gets into the water jacket. I like to fire up a rebuild on straight water to check for leaks. If it's all tight, I drain the water while it's still warm to help float-out the oil-slick of the vasoline and refill with a 50/50 mixture of the green stuff and water. I know it's probably a good idea to use one of those soap-based radiator flushes to help cut through the rest of the petroleum residue, but I haven't been arsed to do it yet.

 

are the performance gains worth the price of the gaskets, the supplies (bits, sanding drums, templates) and the time and effort?

 

absolutely!

 

what could I expect the estimated torque gain to be?

 

torque? probly not a lot, but ur top end would move a lot closer to ur red line than it was before, and likely be higher hp... think of it as going to a more extreme cam on a piston engine

 

I dont need more top end, I need low end. my problem is coming off the line I need to be able to get out into traffic

 

interesting, i've not relied on bottom end to get me into traffic... especially on the highway... going 60, drop it to 3rd and let it rip, its all top end from there

 

I'm not talking highway, already rolling 60, no problem coming off of a an on ramp onto an expressway, I'm all set there. I'm talking about sitting at the exit of a parking lot on a busy street and PRAYING there will be a break in traffic. or if I need the other lane it would be nice to be able to get in front of the other people instead of having to slow down and **** off everyone behind me while I'm looking for an opening next to me

 

hmm thats something i've never had to put up with in my rx7's or even my repu... i dunno what to tell you man... mine have always had plenty of power... street ports help out incredibly as well...

 

You do gain torque, but it moves higher in the RPM range of the engine. Fellow forum user peejay has said he still has enough low end torque after a port job to keep it in 5th at low RPM and it'll still accelerate. I'm not sure how large his ports were, but I think he may have only done a basic cleanup of the stock router/milling of the plates.

What you can do if you don't want to change the timing of the ports is to just clean them up internally. The power and efficiency gains will be enough to justify the $100 expense of a simple resealing job, not to mention the great learning experience (college can't beat that price!!). All you have to do is to smooth all the sharp edges and remove all the casting flash. Use a finger to feel all around inside the port and keep grinding untill it's a nice ergonomic shape (or whatever feels good to you, hehe).

Then again, this is coming from somebody who has already done a couple engines and is comfortable/confident with the tools required to port and remove/install engines etc. If it's your first time, you might want to start small and work slowly. I did. Then when I rebuilt the engine after it overheated, I ported the intakes even larger (My engine's ports are now too large for a dellorto).

By the way, my 13B feels pretty good at low RPM with its streetport. Of course the 460 geared diff helps offset the truck's weight, and the JDM Hitachi carb probably helps a little. A Holley is tempting, but I like the low RPM action of the Hitachi. I'm not sure how a bone-stock Nikki will do on a ported 12A. There is always the Sterling carb option (I've read rave reviews and will get a Sterling carb for my 12A when I'm ready to dive into my 12A project).

 

Maybe your exhaust system is clogged up? The exhaust on my red REPU was made poorly and its old engine had severe amounts of missing chrome. It also had a Facet fuel pump which could hardly keep up with the engine. It was a very gutlless REPU. My white one has none of those problems and the difference was quite noticeable, even when the white truck still had stock ports. The red one's problems are being remidied at this time.

Are your secondaries opening?

 

secondaries sound like they are opening, tires sqeal, even chirp going into second when tires are still cold, it just takes forever to get up to any kind of speed. I know I just stated a HUGE contradiction, because OBVIOUSLY you need torque to break the wheels lose, but the acceleration is just not there

 

could the exhaust get clogged up in a couple years? its a racing beat system that was SUPPOSEDLY put on two years ago

 

Man, this keeps getting stranger and stranger. RB exhaust systems are supposed to work very well. I bet it's your engine's low compression. My red REPU's engine's compressions was never tested, but its low power was still high enough to break 'em loose pretty easily. It didn't accelerate worth anything, but it could still burn 'em off.

Does your engine have trouble starting when it's hot? If not, try disabling the hot start assist motor. None of my trucks have that feature, and the red truck's engine would always be hard to start if it was hot and was accidentally stalled or whatever. I also looked through the exhaust ports and could see large areas of missing chrome. The apex seals and springs felt really good though. Try to determine if your rotor housings are missing any chrome.

 

hot start assist motor? I have no idea what that is and am willing to bet I dont have one.
racing beat "holley" intake with edelbrock carb, racing beat header and exhaust system, no omp (premix MMO religiously) no emissions, holley fuel pressure regulator
guess I'll pull the headers and see what I can see

 

Don't take this wrong, but, is your Edelbrock tuned properly? Those are great carbs, but like alll others if isn't right you aren't going to get the pickup you are wanting. My buddy got his all out of adj. and wasn't worth a damn of the line.

 

That's what I was gonna suggest... If you got *** for mixture, no spark half the time, or vacuum leaks in abundance, you're going nowhere.

How's it run, what's your exhaust look like? Soot all over the tailpipe?

Remove your spark plugs, how do they look? Black and nasty? White and cooked? Or a light golden brown?

Huh? I was under the impression that I needed air tools and a serious air compressor... You're telling me that I can run down to Home Depot, pick up a Dremel or Black and Decker RTX and do a port job? Will it even cut through the iron housings?

So how's this porting template work? I slap the porting template on, I color in the area where I can see through the template, and I remove it and cut away what's colored?

How do I clean up the port? I assume it shouldn't have rough angles, so I need to taper it off at the ends or soemthing eh?

If it saves me $300 on my rebuild, I'm willing to try... Maybe go down to RP Performance or PFS and pick up some old housings.

 

https://www.rx7club.com/showthread.php?t=342527


one of them had to be telling the truth

 

refer to my SE porting thread, i used a dremel for all that..