I'm not saying it can't be done wacky, I'm saying unless the motor is built for it, it shouldn't be done. Sorry guys but running 9k rpms and above will chew up the housings if the rotating assembly isn't balanced. I'm not saying it will kill the motor but it will be useless if you try to rebuild it.

 

true story. I can feel when the motors harmonics start to get out of balance. On my 12a its right about 7.5~8k, after that you know your hurting the longevitiy of the motor and usefulness. If you want to make 10k all day and have a rebiuldable motor (and I hate to say this) you need to consider other options. the 10a has thinner, lighter rotors and far less flex in the higher rev range (if ignition system is stable) Consider talking to jeff 20b about biulding a two rotor or four rotor 10a with 2mm seals (yes I know it wasn't done from the factory) you will find that
1. you can much higher revvs
2. your motor will be smaller
3. fuel consumption will go down
4. longevity will go up
5. overall power will be the same
6. most 12a parts are usable (cheap)
7. boost at high revvs are possible (big power)
8. motor will shed over 40lb of fat if you stay stock. if all aluminum then you will lose 60 lbs~70lb depending

think about that idea. 150 hp from a 150 lb motor....mmmhhh sounds like sex to me. lol

Cheers

 

can feel harmonic??? wow you must have bionic senses but I bet its detonation due to leaning out on top end. in other words, low fuel.

longetivity?? what made you think that your motor will last long with turbo.

 

I don't know where you live, but finding 10A parts in the United States is incredibly difficult and not cheap

 

my input is you have to do all the oil modds and are balanced with the right carb for the ports 10k is easey and it will last for a long time its all in how the build is done theres so many little things you can do to make the motor handle these high rpms

 

When they blow, you'll know you've exceeded the limit........

 

Glad you asked. The 10a had much shorter apex seals then the 12a or the 13b, as such the stress that the seal is under is significantly less. dealing with the engineering portion of this you will find that the stress a part is under due to high revvs becomes exponentially higher. Because of that the weakest portion of the seal is the part you have to worry about which is the center of the apex (because it is furthest away from the irons) meaning, shorter seal is a stronger seal. I know you cannot find 10a rotors easily, however you cannot place 2mm seals in a 10a either. they have to be made, which means engineering (gasp). Anyway the math says that if you build a 10a motor with modern technology and design work you will get a motor that can withstand over 14k revving (did this little project for one of my engineering classes) and with PP ports I estimate based on the 12a's numbers and the old 10a's numbers that at 12k you will make about 250 to 300 hp assuming you can continue to feed the motor correctly.


As for the turbo. keep low boost and doing the above mentioned motor design with a 8k limit you will find that the efficiency of the motor will increase. this efficiency increase can then be used by a ecm to limit power output to original specs and thus improve longevity due to the higher efficiency rating (less foot on the pedal equals less load on the motor equals longer engine life)

 

easier said than done. Whats the point of adding turbo if you cant drive it like the way its suppose to be driven. maybe Im just from the old hood where trailer queens dont exist.

 

lol, some of the new ecm out there have a chassis dyno that limits overall volume of oxygen injected into the motor. Basically if your set max output is 175 HP you will be at that power at a specified rpm and you will stay there up until the redline. same with torque. Basically the motor will act like and electric motor, except it will use a direct chemical reaction instead of a electric reaction (more power and energy efficiency). Like the power curve of a third gen rx7 with everything stock. The power climbs to 255 hp (debatable) and stays there until 7k. That would be NIIICEE in a first gen with 30+ mpg. thats my opinion though. I get 15 mpg with my 12a and weber ida 48.

 

I hear you bro. Wish there is something out there but its a fact, you got to pay to play.

 

yep thats true too. Overall I think to real limit for a street port 12a (assuming that your using all the goodies) is about 200 hp w/o turbo.

 

 

What about a street port 13b? What kind of goodies would I need?

 

There have been a few injected 13B's on the forum making over 200 at the wheels...but not much. Maybe 215-225RWHP max. Intake is the limiting factor....which is why I'll be choking down a massive 62mm Terminator carb...as a test. It is a fact that 55mm dco sidedraft Webers run fantastic on streetports. It all depends on how much $$ and time you want to spend to try something different.

I think a ported 13B cosmo motor with large carb or ITB's would be as far as far as you can go on a streetport. Rebuild it with 91 n/a rotors or Rx8 rotors (so some sayith) and you've got a massive oiling system, stock, with massive ******' bucket ports! I would bet a properly built and tuned N/A Cosmo 13B would easily make 250RWHP.

 

But the exhaust would have to be huge, like a 4" OD pipe = too loud for street and the intake ports so big the side seals get chewed up in no time. = very small longevitity. And I still think 225rwhp MAX

 

A street 13b (renesis) is the best your going to get with a street setting. No mods necessary. If using an older 13b from the 80's you will need alot. high flowing oil pump and higher oil pressure, you'll need to rebalance the motor and if you are going to be higher revvs (like what the Renesis motor can do) you will have to lighten the rotors and harden the stationary gears, use three window bearings for the rotors and clearancing of the rotor tips (lower life for the apex seals, approximately 50~60k before rebuild required) either a high flow carb (weber IDA 48 or equivalent) or aftermarket fuel injection. approx. 240 hp

With the 12a you will need all of the above AND you will need the aluminum intermediate plates, ceramic seals, and finally aluminum flywheel. All in all you would be best going with a renesis motor, it would be cheaper sad to say. Either way you can be sure that the motors I have described are top of the line for the limit you placed (street port)

-richard

 

I beg to differ on the aluminum center iron. One of the big reasons people use them is for the weight savings. Other than that, they have a surface that it harder than the stock irons. Nothing to gain but less weight and possibly less wear (which lapping will cost you tons less). Also, ceramic seals are not needed unless you feel like revving over 8000+ on a regular basis (8500 is max for steel springs before detrimental damage occurs) and get boosted. The steel springs are great for boost to 8k, the ceramics for 8+k of NA or FI, and the carbons for 8+k NA. You can also use the stock flywheel and assembly as long as you have it balanced for the rev range you plan on keeping it at.

When over 9k (or if you are paranoid, 8500) it would be in your best interest if you install a scatter shield and/or a security blanket on your transmission, unless you don't like your feet much.

 

Not on an N/A motor! SDJ style header/or long primary systme with 2.25 instead of the RB 2"....back to 3". No more is needed on N/A motors! A couple presilencers in each primary, a borla/RB/Rotaflo at the end will cork it fine. Remember, its not a bridge or P-port! Just a MASSIVE SP!

BTW...have you even seen an opened up, bone stock 13B cosmo motor? Imagine SPorting it!

 

IIRC, the smallest venturies you can get for it is a 50mm

 

Yeah, I hear ya but the streetport can only flow so much so once it's all grinded out, it's a game of intake an exhaust tuning to get the last % out of it at that point.

Some of the few rx7 13b Streetported motors that can get into that HP territory with a carb are the Mazdatrix SCCA E Production level motors and those pipes are 4 inches back there. Not to mention really really LOUD. As in 102db limit at the track.

 

bigger exhaust is not always better.

 

Custom pare!

 

Gosh...I hope that rear muff isn't a Flowmaster!

Plenty of ways to get N/A's quiet enough...even P-Ports!

 

the reason I say that the alum center plates are needed for the 12a is that the stock 12a center plates are a little odd and need to be changed for the motor to match the current design work. also the harder those plates are the less issue of flex at high rpms and the wear issue (the motor I designed is built to last a much longer time and higher stress then stock) you can build a car using 2 of 3 things:
1. cheap
2. safe
3. fast

which two do you want?

 

i want none