scathcart

You'll either need carbon (so no power adders) or ceramic apex seals.
Steel apex seals chatter like mad above 8500.

gus5891

well i'm sure i can do it in my parents living room but i cant have it sittin there for weeks. we are southern rednecks but we live in a more city like place an my parents are kinda gettin into this city thing

gus5891

the apex seals in my car were changed about 10 to 15 thousand miles ago(trust me i started whinin when i learned this)so i thought i could just reuse them

scathcart

Sure can, if they're in spec.
If they are steel, keep it under 8500 or you housings will wear like mad due to seal chatter.

scathcart

To clearance and build a 9000+ rpm motor usually takes me about 40-50 hours.
Using stock intake manfiolds for above 8K is a waste of time.

gus5891

what are you suggesting for intake manifolds then

scathcart

Custom. There's nothing else available.

Then again, I would never start with a 6 port block if I wanted to use sideports for above 9k.

gus5891

yeah well i'm young an learnin how to do this stuff. i'm pretty good with piston cars but as i've learned everything i know about piston cars i can throw away with a rotary car. just gotta start over an learn how to work on these. not to sound cheap but money being a issue what would be said for the condition of the gaskets being they only have a few thousand miles on them would i need to change all of them or are some of them reuseable. i really aint got the funds to go all out altho i think i'm gonna have to

scathcart

I think if this is your first engine build, and money is a problem, keep it under 8K.

High revving motors are for competition where, simply, revs are required to make the power.

If you're just building a cheap engine for you to tear it up on at the drag strip, build a street-ported engine and throw a couple hundred horsepower worth of nitrous at it.
Faster. Cheaper. Easier.

gus5891

i know enough to know nitrous can blow a motor. i dont want to cook it that fast.

scathcart

You're right.
Nitrous can kill a motor.
So can very high revs.

I've pumped over 350 hp worth of nitrous through a rotary, that had much less mods than are required for a 10K rpm engine.

Really, you're never going to build any successful motor. You're a kid who is day dreaming about building some high-screaming engine for no point. You can't afford to build a 10K rpm motor, nor do you have the skills, so stop wasting everyone's time with your fantasies.

gus5891

dude relax a little i'm not just tryin to take up everybodys time what i'm tryin to do is learn from what yall tell me. an from what i have gathered already is that i dont need a high rpm car. my dad is the one who suggested that high of rpms so i came on here to ask what i would need to do that. what i learned is i dont need that kind of rpms i just need to fix it right an run it right.an the fact that you tell me i'm not goin to build a successful motor gives me all the more reason to prove you wrong.O an the skills to rebuild this engine everybody had to start learnin somewhere

fastrotaries

if you had acces to a: lots of money. b: a full shop, & c: had a clue. you'd know that you'd get waaay more power, and spend less money, doing a 20B na project rather then some high revving motor. For some reason ricers have chosen this as the staple for making power, Just because they heard from some other kid, who heard about it, in a japanese magazine. Yes it can be done, but right now, not by you. If you need to ask .5 of the questions...you're out of your league. There are several books you can purchase and read about. Some a little more technical than others, but I suggest you start reading, rather just have a bunch of answers dropped on you lap. Best of luck, and remember you have to start somewhere.

pengarufoo

+1 for high revving 20b

12akid

most shops told me all you need is good brigde port and u can go past 10krpms

snowball

their is a large diffrence between making power at high RPMs and being able to run safe at high RPMs

Kyrasis6

Yea when I measured my RX-8 eshaft the front and rear journals where a mirror image of eachother to .0001" as well as the journals for the rotors. The surface finish of all surfaces was right around 2 RA with one spot non-critical spot reading 5 RA. My polishing attempts to get the RA lower was useless as they only checked about .1-.2 RA lower after polishing by hand.

It is by far the highest quality OEM part I have ever measured.

Kyrasis6

You can blow just about any engine quickly if you dont' know what your doing and not taking the right precautions you can do just as much damage with turbo as you can with nitrous the same goes for overrevving. If you don't have the engine setup for what you are doing it isn't going to hold together regardless of what it is.

There are a lot of things to consider about apex seal chatter, just not the material of the apex seal. Surface finish of the rotor housing, hardness of the seals, clearances, weight, rpm, the spring rate of the apex seal springs, surface finish of the apex seals themselves, etc.... I would imagine an engine with an apex seal clearance of .001" would have a lot less chatter and hold together at a much higher rpm than one running the same speeds with .002" clearance.

arghx

iTrader: (3)

.

SCCA RX7 RACER

Mega Squirt System
Mega Squirt System

ericgrau

iTrader: (1)

To answer poster's question:
On a race car: mods given by others, bridge/peripheral port (peripheral is better, costs more). Car must spend all its time around redline to show any improvement.

In a fantasy world: valves that close the peripheral port and open the stock port at low to middle rpms. The auxillary ports would handle the "middle" rpms (~4k-7k).

On a street car: Don't bother, for reasons given by others. Get a VDI intake, full performance exhaust (Racing Beat is deservedly popular), cone filter, cold air box around the cone filter. Then get it street ported. Stick in the S5 rotors for an 8000rpm redline, or get what is necessary for the highest useful redline on a street port.

Which leads to my own question:
What are the "oil mods" that need to be done to raise redline? At what rpm is the power peak on stock porting? At roughly what rpm does power drop off? At what rpm is the power peak on street porting? At roughly what rpm does power drop off?

Carbon seals don't last nearly as long as steel ones, btw. So you/I may hit a wall at 8500rpm unless you don't mind frequent rebuilds to replace the apex seals. That's assuming the powerband on a street port even reaches 8500rpm.

gus5891

well i'm figuring on just puttin the s5 internals in the car for now an just go from there

Kyrasis6

You should be able to look in the dyno section and get some comparisons. Kahren has a really good post in there with a pretty heavily modified NA engine.

Here is the link: Kahren: TII NA Build 186 hp



Looks like power on that build fell off around 6,800-7,500 rpm. He says in the post that the engine was initially going to be built for a turbo but decided to stay NA for the moment which was how the car was dynoed.

gus5891

that still looks like pretty good hp an torque to me though

Kyrasis6

Then why are you worried about rev 10k?

End of the World

^ We're all sitting down here like WTF?