i have an s4 na thats getting streetported, i notice alot of people use s5 rotors in their rebuilds instead of s4.... well im stuck with using the s4 ... so i was wondering how high they are made to redine and how much hp i can expect to max at...

im hoping to make 170-180+ hp at the wheels and make this at around 7200+ rpm

 

people use S5 stuff because the manufacturing tolerences are closer the the S4 counterpart. they are also lighter and if you are trying to make a light rotating assembly, lighter the better.

and they are higher compression too

 

well i know all this , but im stuck with my s4 stuff so wanted to know the max on them.... ill be pushin them with a mild streetport

 

The stock redline is how high it's rated to go.

 

I am getting 170 RWHP using S4 non turbo rotors.

Redline is gonna stay around 7000 though, no matter what. The heavier weight of the rotor is the issue. The only advantage that the Renisis or S5 non turbo rotors have that increases their redline is their lower weight.

 

do you have a pic of the dyno when u got the 170whp and mods ?

 

Probably still in the 2nd gen Dyno and 1/4 mile section, or might be here in the 2nd gen section.

But the engine/drive train mods are:
cone intake with fresh air ducting
custom exhaust (including 1 highflow cat and single muffler out) flow tuned for non turbo engine flow at 4.5k to 6k.
rebuilt S4 with a mild street port on the engine (except aux ports which are a little more agressive with close held until about 75*).
extrude honed and matched Hybrid S4/S5 intake with air pump actuated VDI and Aux port operation and cool coating (never tested to see what the hot soak intake temop was before so I can't say if the cool coating did anything).
CDI with Jacobs wires and Denso Iridium leading plugs
Remapped ECU (runs leaner at 5k and up than stock) and advanced timing (probably a SAFC would do the same thing- rarest RX got around 15 HP as I recall just tweaking with the SAFC at above 5k)
Tweaked AFM
4.1 Non turbo rear end (car originally had the 3.9 as it is a 88 vert)
Redline Super Lightweight shock proof in tranny and read end (no ****- 3-4 HP peak dyno RWHP change right there)
15 lbs flywheel
No EGR or precats.

I know there is a couple of other things, that I can't think of right now.

See my big thing was to pass CA emissions, so most of the emissions systems are simular or intact. Yeah I would get busted on the visual for the no EGR and missing cats, but it does pass the sniffer test.

 

Just curious, but how would removing EGR affect your smog test? I was never able to even see mine until I removed my intake manifold, unless they remove that how would they know if it was there or not?

 

ive tried to stay ontop of what the n/a guys are doing but this is new stuff for me.

care to elaborate on the ecu remap and the AFM modification?

 

In CA the test (once every two years) requires the initial testing technician to confirm there is a EGR valve if the sticker on the hood shows one. Without one you would fail the visual test (visually confirming everything is there and intact).

You can see a S4 non turbo EGR valve, if you know what you are looking for and where to find it. Of course it is even easier just to test it by unplugging the vac line for it, but again the smog tech must know what he is looking for (another reason I take my cars to a mom and pop smog test station that hs absolutly no clue about rotary engines).

 

There was another member that was intrested in making repplacement chips for the S4 non turbos and S4 Turbos. He wanted me to sell the chips through my webstore and contacted me accordingly.

I asked for a couple of samples as well as a dual chip set (the S4 verts use two chips to run the engine) made to my specs. He sent them too me and then I never heard from him again.

They all worked fine except the Turbo ones, which I could never get to run right.

As far as the AFM, I don't want to go into details online with it until I have confirmed there are no bugs in the set up and anyone can do it. The last thing I need is a bunch of people copying the mod, and it blowing up some engines.

 

I just had an idea, couldn't you just block off the EGR port and mount the valve on top of the block off plate for the visual?

 

My autotech teacher used to race rotaries in the 70's, he's gone to 17,000 rpm on stock weight 12A rotors with staked rotor gears, weight isn't an issue.

 

17,000... hahahahaha expecially in the seventies. .

 

I've done this- remove the EGR valve, clean all of the gunk out of it with some acetone (or similar solvent), plug the passages with red RTV, and remount the EGR valve. Even got the vac line still going to it, but the EGR solenoid valve is non-existant.

 

I remember a story a while back of a guy with a 12a fb and he was racing and he had a mishift and hit about 12,500 rpms, heard a pop and thought his motor was toast, it was only a minor thing that happened and he was back on the track in minutes. I dunno kinda random

-Andrew

 

He's not lying.

I visited RXSevenSymphonies school to use their press when I was doing my suspension bushings and had a chance to talk to his teacher, Nolan.

Nolan used to Race RX3's all the time, Road Race. I was talking to him about redline and such with rotaries and how I wish I had built my engine to rev higher. He then told me that with proper fuel and porting you don't need to do much special to have then rev high without a problem. ALL he did was stake the gears. He did no system balancing, no hardened stationary gears, nothing like that. He told me that from the factory the balance is pretty damn good and he never saw it necessary to get it rebalanced for higher RPM use. This guy is pretty knowledgeable and he has a bunch of cool stories from his racing days. Oh yah and he used STOCK weight rotors and stock weight system basically, no lightening of the rotors or anything.

 

what does that mean?

 

wow, i wonder what 17,000 rpm's sounds like.......prolly like buzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz, but a lit more intense


*sits and thinks about weedwacker noises*

 

12A rotors are considerablly lighter than 13B

 

In my case the EGR valve diaphram is in the way of the VDI intake.

I have been working on a shorter EGR, but it has not been a real high priority.

 

Well according to mazdatrix the 76-82 12a rotors were .11 pounds heavier than s4 13b rotors, not sure how much the earlier 70's 12a rotors weighed, but im sure its not much different? Not a 10,000 rpm difference surely. Although the shorter e-shaft probably helps.

 

An explanation of staked from some site: The drive disk is staked to the shaft - you know, hammered in place and staked with a center punch.

Same purpose as the Racing Beat snap ring rotor gears, just a different way of keeping the gears from moving

 

And no one has mentioned the chatter marks on the housings found at that RPM.

 

how exactly do you benefit from staked gears? just a tighter system?