c2t88rx7

Should it be done? What does it take? These are questions that people ask all the time, and everyone has a different answer.

Therefore, I made this thread for all of you to discuss your opinions. Share and discuss your views on what it takes to build a high revving 13B-REW (Let's say... 10k-13k???) and its advantages/ disadvantages. Just to get some insider info. Thanks!

Shamrock.James

some tips:

1) it needs to be perfectly balanced, to the very 1/10th of a gram, unlike your english

2) upgrade injectors

3) will need to be ported to allow for such a high RPM

4) you could even cosider installign secondary plaatary gears for a smoother run

5) you will have to shed weight off clutch etc.

6) it will be undrivable as a daily car, which is what you are thinking, so give up now.

87base RX-7

i dont care ill still drive it on the street cause i jus love that scream!!!!! though my recipe is a renises swap for more power/streetable bridge port and already revs real high and should have no prob gettin it too 14 grand

peejay

Consider this:

Going from 5000 to 10,000 will double your car's speed.
So will going from 4000 to 8000.

However there is 56.25% more rotational inertia at each given RPM point equivalent (5000 vs 4000, 7500 vs. 6000, 10,000 vs. 8000, extrapolate linearly).

This means it takes more HP to accelerate the engine. If you compensate for the 25% higher RPM with lower rear gearing, that difference extends to the entire drivetrain, since *everything* from the pinion gear forwards will be spinning up an equivalent percentage faster.

To accelerate the car you must accelerate the engine. And unless you are tractor pulling or dyno racing, *acceleration* is the point behind performance engine mods.

Energy wasted on accelerating the engine/driveline is energy not spent making the car go quicker!

ALSO... the higher spinning engine would have to accelerate at a faster RATE then the lower one, for equal acceleration. If it took 2 seconds to double speed, the higher RPM engine in this example would have to accelerate 2500rpm per second, while the lower-revving example would only have to accelerate 2000rpm per second. This increased *rate* of acceleration *also* saps HP available to accelerate the car.

And then there's the engine longevity factor... no engine in the world lasts longer by spinning really fast.

Don't worry about making an engine higher revving - worry about making more power in your existing (or lower!) RPM range.

Sponge Bob Square Pants

IMO it's not worth spending the money necessary to allow the engine to rev higher than 9,500 rpm or so for a street application.

c2t88rx7

Hmmmm.... havn't seen any advantages

So at 9,500rpm, how much torque will I loose? I was thinking about 9k. Turbonetics T-76 w/ single ceramic ball bearing.

KEEP ON VOTING, PEOPLE!!! LET'S SEE WHAT EVERYBODY THINKS!!!

j200pruf

iTrader: (4)

There is a guy in Aus, I belive it is Rohan Ambrose that spins his birdge ported 4 port 13B to 12,000RPM. And he is making 300HP.
And as far as what you need.
Get Cryoed Race Bearings
Guru motorsports 2 piece crank and hardend stat gears.
The Guru chomemoly 10 pound flywheel that is made to use 5.5 inch multiplate clutch would probably be a very good idea.
Higher oil pressure regulators
Loop Line.

re10

Run it as a N/A - forget the turbo idea... getting around to 10K is no problem with a well built PP. What are you going to use it for?

EpitrochoidMan

Horsepower=(torque x RPM) / 5252

However, lots of RPMs means lots to worry about. I would definitly have a scatter shield over 10K. Not to mention the short life span your engine would enjoy.

j9fd3s

iTrader: (3)

you need BIG porting to make power that high.

chairchild

* centre bearing
* lightened rotors
* balanced counterweights
* carbon apex seals
* run it N/A
* lightened flywheel and clutch
* huge PPs on the inlet and exhaust
* uprated fuel system
* straight-through exhaust system
* multiple air filters to give virtually no restriction
* uprated bearings
* coated internals to cope with the increased friction

~Should see you to around 13-14k

rotoboy20

in my opinion, you'd be better off useing a 12a or an 11a. smaller internals = less mass = usable power in the upper rpm range.

look at it this way.

i race nitro powered radio control cars. the engine i use is a mere .12 cubic inches. it spools up to 43,000 rpm in a split second, much like a cosworth formula 1 power plant. although the cosworth doesnt do 43k rpm.

now to get that type of power and response out of a 12a you would need

twin 600 cfm four barrel carbs,
extreemly large porting on intake and exhaust,
three inch exhaust pipe about 4 feet long with no resinators,
and of course all the nesacery low friction coatings for the internals, every thing must be balanced, and i would advise that all nesacery parts be cryo treated.

it would also be a good idea to use a electronic distributer, you know, the kind without points. and an intence set of incredibly hot ignition coils.

not to mention the race gas to feed the beast. oh and you might wanna pre-mix 1 ounce to a half gallon of fuel.

messy i know, but the oil acts like a coolant. also it will keep the seals lubed up enough to maintain compression at such high rpms.

ill post a web site that has a .30 cid single rotor engine. its for model planes. you say that two 600 cfm carbs would be too much then you will get the picture when you see the carb on this tiny motor.

chris

rotoboy20

http://osengines.com/engines/osmg1400.html

re10

I think you mean 10a, not 11a

A friend of mine built up a 10A J port, and managed 13K rpm runs in second gear (circuit racing) without too many drama's.

RX794

No one has mentioned this yet, so I think I will. You'll need a different intake manifold design that's made for a higher rpm motor.

rotoboy20

if im not mestaken there is an 11a, i could be wrong.

11a is also a type of carburator for model cars, so i may be confusing myself.

i still think there is an 11a, didnt really run in production, but there was one produced by mazda.

Kenku

Uh... well. Food for thought.

You can build for more RPM, but you'll get to a point pretty rapidly where the engine won't... well, do much of anything at midrange RPMs, and just plain won't start. Which really isn't very useful.

The R26B from the 787B LeMans car made about 700hp at 9000 RPM. The slide-trumpets broadened the power curve, but if anything reduced peak power. But anyway, that's 350hp out of a 2-rotor. Someone build that; I've not seen anyone do that who'll talk about it. All sorts of threads here and there about people wanting godawful huge RPMs but not having any idea on how to get as good of efficiency on a race peripheral port motor as Mazda did 13 years ago.

To my mind, everyone's asking the wrong ******* questions in here whenever big-power NA motors come up. Not "how high can I spin things?" but "how can I make the most power by such and such RPM?"... that's what I'd *really* like to know. Looking at most forms of racing, what was done 13 years ago should be able to be copied but... yet, noone will say that they have even managed the same power with an NA 2-rotor. Hell, people should be *improving* on it... where's that?

Bah, don't mind me, just grumpy.

Gearhead

iTrader: (1)

I'm not sure how many of you have been around high RPM rotaries. My roomate built 2 PPs with Mazda ($$$) PP housings. His first had Racing Beat housings. Anyways, the sound is great. The power is great. Yes, you can drive it on the street, but a tuned turbo car will outrun it for about the same money... and you won't get 6mpg when you're cruising to the store, nor will you pour $12 of Klotz 2stroke in the tank at every fillup. This was probably overkill. You also won't have to deal with the fouled plugs ($25 apiece), noise complaints, and cops as much. In retrospect I'm sure if he had all that money back, he would have built a turbo car. A mutual friend of ours has a Gotham racing built car that will outrun his CBR. My advice, for what it's worth, go turbo and shift at 8.5k or lower.
Don.

SPOautos

The real benifit would be having the ability to keep going up with the rpms incase you were say...at the end of the track (drag strip). You dont want to shift right at the end so you hold it and keep going to 10K rpms. So what if your tq drops, with the additional rpm your hp shouldn't drop to bad if you have a decent intake manifold. And even if the hp did drop real bad I doubt its going to be enough to make up for the much high gear you'd be shifting into.

I think it could be real usefull in that type situation

STEPHEN

re10

Sorry to say you are wrong... you may be thinking of the 13a (front wheel drive RX87 Luce from 1969'ish)

As for the comment re better to go turbo - depends on what you building the car for... as a daily driver no question the tubo is the nicer ride. If you are running on the circuit, turbo motors are rated in a higer class... over here rotors capacity is rated x 1.8 and turbo rotors x 3.0.

kenn_chan

My thoughts are pretty mild on this but until a 98, I was running a RE Amamiya 13B PP, 12K RPM wasn't hard to hit but it plays hell on your plugs, always either fouled or burned up, one or the other. 330 on an engine dyno, was the readout when I picked up the engine, and it lasted about 2 years of weekend raceing on Fuji Speedway. the occasional 1/4 mile blast was when I hit 12K, and to be honest its hard getting the launch correct is the hard part, 1/4 the time ya bog it the 1/4 of the timje ya over rev and lose traction entirely, and the other 50 percent well lets just say the the Nissans, GTR or Zet's and toyota supras of the world hate you! (Oh 1st gen SA22C with OS giken tranny parts, Nissan diff custom welded and fiberglass fenders, hood, and rear port gate to replace the glass hatch)

re10

So what killed it - what broke???

Jay7 Nyc

iTrader: (3)

http://www.osengines.com/engines/osmg1400.html haha thats too funny RC rotaries I need one for my Yokomo!

Dr. Rotar

I wonder if you can mount that mini rotary to a rc car. I have talked about machining a mini rotary for almost a year now. Guess someone beat me to it.

rotoboy20

a radio controled rotary car is in the works, it wont mount to conventional R/C engine mounts. im pretty much building from the ground up, the suspension will be borrowed from another vehicle.

otherwise id have it in my Kyosho Vone-RR!!!

-chris