Actually I'm running an 83 mani with a 79 carb. Strange, but it works. I guess since I'm not using the vac ports for emissions. It has a Pacesetter header... Not the best, but better than the cast iron manifold. It definitely still makes power over 7k. I was thinking of taking it to 7.5k on hard runs. That's where the fuel pump is going to show it's dark side though.

 

The redline is not a shift point... it's a warning point, the limit of "safe" operation. It's determined through engineering, based on materials and structures analysis, and confirmed through testing. There is always a healthy "safety" factor included.

In essense, it's the manufacturer saying "we don't guarantee that it won't come apart, above this speed." The stock engine could well (and often does) survive operation well above redline for an indeterminate amount of time... but the designers are basically saying "you're on your own, there."

Increasing the carb or exhaust size does not change the redline, though it will make it easier for an engine to rev past that limit or produce more power at higher RPMs. But intake and exhaust changes alone don't make any changes to mechanical structure, so they don't improve the structural integrity upon which the redline is based.

Blueprinting, balancing, clearancing, lightening or treating of rotating or structural components can dramatically increase theoretical redline. Dyno testing (often to destruction) can confirm a raised redline for a design.

 

Rev too high, and your apex seals will start chattering because they are spinning so fast they can't hold themselves against the housing. Once you start chattering, you are slowly chewing up your motor.....

 

doesn't seal chatter start at 8400 RPM? So 7000 would be safe as far as seal chatter.

Other than seal chatter you have to worry about e shaft flex and stationary gears.

 

chatter ? shaft flex?...what?

 

The vibration of the internal parts starts to increase at higher RPM. The seals and eshaft will flex and chatter up against the housings. Rotor bearings can do the same. The rotor can actually wobble back and forth a hair.

 

where chatter starts depends on the condition of the apex seal springs, rotor housing surface, apex seal condition etc etc

i wouldn't rev a 30 year old motor too much higher than stock, maybe 7200.

 

Sterling, what is a good Fuel pump, Regulator and Fuel gauge combo will be fit when I purchase a carb from you. I am stuck on your Sterling and Sleeper combo. My car will be a daily driver with some kick. I am thinking of ...well, I hope to put in my order in by the end of Aug09. I am working crazy hours double and triple shift's in overtime sleeping 2-3 hr to get what I want for my car. I am soon to order a Carb from you, still working on my list from Re-Speed. I want to say thanks for your contribution to us RX7 cult members.

 

A good point that's missed by many.

Redline is a construct that takes into account performance, powerband, wear factors and mechanical limits. Once mods are introduced during a rebuild, redline loses it's original defined limit. Carb, intake and exhaust mods change/raise the powerband and useable rpms. When an engine is rebuilt with oil, porting and stress mods, (i.e., hardened stationary gears, balancing, clearencing, 3 window bearings, etc.), useable powerband and rev limits can increase to as high as 11k, depending on expectations of longevity. Keep in mind most clutches are rated to a max of 10k rpm. For longevity, depending on porting, 8k is a workable limit if the proper mods are done. For a full bridgeport or P-port, 9-10k can still net power, but not longevity.

 

the book Rotary engine (google it) has all the stress graphs and such for all the internal parts. the neat thing about a rotary is that you can balance and use carbon seals and stuff, like mine; glen says i can rev it to 11k (which is scary!).

but my motor is NEW, subjecting a 30 year old engine to big stresses isnt a great idea, imo.

and piston engines have it worse, redline on say a b18 honda is like 1 rpm before the thing comes apart on its own (seen it! we get sponsored by a drag type shop, and they have a whole bunch of broken blocks and heads)

 

Didn't know there was a tech section in any book that showed stress/failure rpms for different parts. Do you recall which rotary book it 's published in? Google yielded many books with Rotary in the tittle.

 

Thread jack!

 

http://foxed.ca/rx7manual/manuals/RE...amoto-1981.pdf

they dont give failure stats, but they do show stresses

 

Really? He's jacking a thread entitled "Need help on a new Sterling Nikki in which the OP (-YOU-) asked about the fuel delivery requirements of a second-hand Sterling Nikki because he's asking me about the fuel delivery requirements of a new Sterling?
So is he "jacking" the thread because he's not asking about what RPM rotaries start to eat themselves, or because he's not asking about your second-hand Sterling Nikki?
Not sure I quite get it, Cross. You saved your buck, so what's the problem with Silvio's question here? Are you totally against the idea that someone might actually buy a Sterling Nikki from me?

Silvio, all the necessary info is on my website. There's a forum there, too, dedicated to Nikki owners.

 

Well, usually whenever you ask your own question in a thread started by someone else it's considered a thread jack, but I was joking... I could really care less. Everyone has to learn somewhere. Maybe I'm a bit of a post ***** sometimes... I guess perhaps I should have started a new thread for my engine wear question, but I didn't want to clog the site up and figured it seemed like a relevant follow up to me getting the higher capacity carburetor working right. I just figured that if you have a smaller bottle neck of an intake and exhaust system and a better ignition system than the factory units that maybe I could pull another 200RPM out of the old 12a and not feel so guilty for over revving it.

On the subject of your work however I think it's pretty fantastic really. Taking a 30 year old OEM carburetor and turning it into a performance carburetor that rivals the performance of Holley and Weber for less than half the price and less hassle than outfitting a full aftermarket conversion. I needed a running carb quick so I chose a used one and it only took me 3 days. If I wasn't so short on time I would have sent one off to you and gladly paid the price and waited however long it takes to get the work done.

 

Thanks for responce.

 

My motors a new rebuild with good compression on all faces. I take mine to about 7500 on a regular. It goes from 5500 to 7500 really fast in first and second gear. getting on the freeway is sooo fun.

Sterling, I'm sure we'd all buy your carb from you rather than buying second hand or going somewhere else. I know I would. But times are bad for about everyone these days. and sometimes we need a carb right now, and cant wait several weeks or longer. I understand stuff takes time. But when the economy picks up I'm sure you'll get tons more orders. I still plan on buying a sterling carb. and keeping my modded carb as a backup.

 

That wasn't the point, jinx. Don't make me sound petty. My annual net from carb sales is a joke. This is a hobby for me, so I couldn't care less if someone buys a Sterling second hand. But to me, it's just a tiny reason they should be all the more polite to those asking questions about the thing.
My gripe is (and always has been) with the "Butt-out, Noob!" attitude in other people's posts, -joking or not.

 

Well, even though you only make some side money from the nikki's I hope you continue making them. I really hope to own one some day. Even though your only making a little money. at least your a recognised and respected member of the the rotary community.