So how many different steps could be taken to structurally increase the redline neglecting power, porting etc...??

I've heard all the common sence stuff, balancing, lightening the rotors, supporting the eshaft with an extra bearing in the center, ligtening the eshaft...

Someone mentioned clearancing the rotor tips... Wouldn't you want to do the opposite and go with slightly thicker apex seals to tighten the clearance so that the seals have less chance of binding, flexing, and have increased heat transfer??

What about stiffer apex seal springs to resist the chattering, or slighly lightening them by cutting a very shallow parabolic shape in the center on the edge inside where the small spring seats?

Of course you have your underdrive pulleys for the water pump and alternator, etc... anything else, any additional thoughts?

 

You clearance the rotor tips to keep them from contacting the rotor housing. And the stock 2mm seals are fine for high rpm's. There have been people running 10.5k rpm p-ports on stock 2mm seals. At those rpms you want the thinnest possible to enhance the sealing properties.

 

Yea I was just reading a post in the dyno section and realized clearancing the rotor tips meant so they wouldn't hit the housing.

I don't plan on running past about 8,500 or so so I'm guessing I won't have to worry about the seals.... I've heard what you said before from others about using 2 mm seals but sometimes I play stupid to see what kind of responses I get back from ppl. Just curious as to other ways to increase redline. In piston engines hollowing portions of the main and rod journals can dramatically increase the crank's ridgidity, could parts of the eshaft be hollowed out deeper? I just got my new one friday evening and won't be able to micropolish and analyse the **** out of it until tomarrow...

Edit: RX-8 eshaft in S4 engine by the way...

 

Hardened stationary gears for one, increased oil pressure, under-driven accessories and main pulleys (to prevent water pump cavitiation and to reduce drag), race-use eccentric shaft oil jets, bearings with "windows" to allow better oil flow...

Also, you'll need a flywheel and transmission that can take those high RPMs without blowing up, and you'll need a scatter shield around said parts in order to keep the driver (ie, you) from getting fragged (ie, dead) if the drivetrain decides to grenade itself.

There's no reason to go past the redline unless you have a pretty aggressive porting though (or if you have a massive turbo or something).

You would need carbon apex seals (for their light weight) after a certain point.

Is this a turbo or an NA?

 

If you're only running to 8500 rpm, all you need to do is get it properly balanced. The hardened stat gears and 3-window bearings would be a good idea if you are going to run that high very often. And a scatter shield is only needed if you run higher than 8500. As long as you keep it below there, your fine. Heck, an s5 NA engine can do that stock. And I don't know about increasing the rigidity of the e-shaft. As far as I know, its perfectly fine for all but the most extreme use.

 

ok. main question. what port are you gonna run, and where do you want peak power to be??

 

Got the RX-8 stationary gears and bearings sitting here as well :-D

 

lol, I didn't want to get into porting on this thread, was mainly speaking hypothetically because in a year or two I plan on building a much more beefy turbo engine that might see 10k.

But, since you ask I plant to run a large street port with Aux porting as well. I'm considering doing a Aux bridge and keeping the sleeves functional for some streetability. I would like it to continue pulling through the 6,500-8000 rpm range. It is my first rotary build so I'm trying to get a feel for what I would like to do in the future.

I havn't been able to find anyone on here yet that has done an Aux bridge and kept the actuators functional, everyone I have found removed the sleeves.

 

Aaron Cake did it, but he also turbocharged it.

 

That is where I got the idea of doing the bridgeport on the Aux, I was originally just going to do pineapple inserts. I'm not sure if he kept them functional though his engine does have a bit of a lope in his movie and I don't think he's taken the engine above 4k yet to really know how it does.

Would be great to see if I can have my cake and eat it too (not to be misconstrued).

 

Use S5 or RX-8 rotors because they're a bunch lighter. If you're really serious about building a high rpm motor speak to an experienced engine builder or shop that has built many high rpm engines. Their information will be more reliable than what you read on here, what you'll read here will be mostly 2nd hand information, or theory.

High revs for the sake of high revs is stupid, don't be trying to increase the redline because it's "cool", have a good reason for it (power up top).

 

i would toss the water pump and move to electric.

 

actually, the electric waterpumps sort of suck in general, and REALLY suck for high RPM.

 

But the aux ports on his engine aren't functional, since the previous owner removed the sleeves.

 

Oh, I thought he said he left them functional. Guess I mis-read.

 

The death of the RPM battle is the crank flex seen as high rpm strains cause fatigue. After all the rotors are not going anywhere unless something holding them gives "E shaft or stat".

I have some theory’s to combat but not yet tested so I will leave that out until I can give further insight on them.

What I will suggest for your desired setup that I feel is a must is a custom intake manifold and plenum. You can use stock Tb if wanted but really get an intake designed for you. You will just see pore results for your efforts if you leave this factory tuned. After all you can polish someone’s *** all you want but with there pants on no one can tell.

 

They make 2 piece 13B eccentrics if you are really serious about this. The don't flex. There are also shafts available with a center bearing but of course you need to modify the middle iron. None of these high RPM options are particularly cheap. Um, I think Kiwi RE is one of the vendors that sells these parts.

Which begs the question, is high RPM operation really necessary on a turbo engine? People seem to be doing fine at 8K/9K.

 

Man, the stock e-shaft is already hard enough to install...much less with a bearing :p

 

N/A going > 12,000 rpm ftw!

 

you guys are ******* nuts with the n/a builds. I'm not looking for an n/a vs. turbo thread here, but after the 172rwhp dyno I just canned it and bought a T2. It would have been thousands and thousands + many hours building the car and chasing down parts + a measure of unstreetability to do any of those really high horsepower n/a builds, and you'll still barely hang with a lightly modded turbo II.

There's an FD guy with a 3 rotor peripheral ported n/a that's doing at least 300whp. I think he's spent over 10 grand on it, but if you're gonna do an n/a build just go all out and do that ****.

 

racing beat race rotors... the roll pins in the rotor gear can give at high rpm. don't know how necessary this is for you.

http://www.racingbeat.com/FRmazda2.htm

i think you should go peripheral port if you're going to go down this road.

 

I must ask the question, why go higher in rpm's? More isn't always better, especially when it comes to rpm's and engine longevity. If you are building a turbo motor, there's no point to going that high.

 

Because being able to rev to 11K is "mad dorifto JDM tyte" and makes them like Takumi :p

 

I'll agree with that 100% "Clearancing the Rotor Tips" would be half a&%ed since you are sacrificing potential longevity for added rpm. Clearancing the tips would provide less support for the Apex seal, subject it to more heat, and decrease surface area for it to remove the heat it has absorbed. So I would say good things to increase reliable redline would be to use ligher rotors, a stiffer eshaft, support it better, and good ballancing.

With the stationary gears wouldn't it be possable to just add a third staionary gear with bearing in the center? Or even without the bearing. That would stabalize the rotor completly and reduce the forces on the eshaft to the loads applied by combustion and torsional flexing...

At school they told me once that if a crankshaft was out of balance by a couple of grams and spinning at 9,000 rpm plus that it could throw the ballance off by and astronomical amount (the example given was 74 lbs!!). So I'm sure proper ballancing is a huge requirment for any high rpm engine.

So what if we where pushing for the maximum redline available (provided there was a benefit) I know at some point there would be problems with the apex seals chattering. I'm sure reducing the flexing of the eshaft would help this how do the race teams overcome this? Stiffer apex springs or less spring install height I'm sure would help but stiffer springs would increase the co-efficient of friction which a race team would try to avoid.

There are ways to help the water pump, properly shaped and sized coolant passageways before and after the pump will help reduce cavitation and decreasing impeller clearance inside the pump would not only increase pumping efficiency but reduce cavitation as well.

High HP numbers are not my primary concern. I work with 800+ hp engines at work and to me getting 400+ hp out of a hobby car is pretty boring. If I where to try half the things mentioned by other members like lighter rotors, turbo, and custom intake I would not have started with a beat up S4 engine and car. To me it is what I can make out of it with my head and hands and maybe a few better made parts. I don't see my current engine build going past $2,000-$2500 on budget.

Iceblue: I would be happy to openly hear some of your theories if you would like to PM me on the topic.

 

LS1.