TOPIC: rx7

Does any one know if this would work on a rx7 12a the old carby kind?

Peripheal, it might. If I recall correctly the old RX7 used a real ahem, interesting, 4 bbl carb, near-unheard-of on any other Japanese engine. Is yours this 4-bbl? Would need to see pics of the underside of it to have an opinion, and it may well be an iron throttle body.
Theoretically, most anything w/ a round throttle butterfly (and NOT a slide type throttle) can be Grooved- but some are "Very" interesting to do! Also I think I remember something about the old RX7's having pretty dirty emissions, but maybe that was an issue from rotor seal wear and hence oil getting into the chambers?
PS- are you in Aussie or NZ?

Tracy G

Thanks for the reply. I don't own this car and it is the carborated motor 12a. I have been hesitant to purchase this car because of the fuel efficiency but i have wanted a wankel for some time and the price is wright. On to the problem with the design, the intake gases mix with the exhaust gases through the spark plug port. I am a little bit conserened with the mixing causing a greater exaust temp due to the lack of a perfict seal in the two chamburs and a beter air fule mix.

I am in the former usa. Hope thats not a problem.

O I purchased the groovy kit but have not used it as of yet.



Thanks
Tracy G

This helps to explain why the EGTs are so high(1600F) and why they shoot flames out of the exhaust.
.

Cooling is usually the #1 focus for people building rotaries.

It sounds like you understand the design issues of the rotary.

I would look at the intake port/manifold design for this 12A and try to figure out if there is anything that might interfere with the new waveform the groove creates.

Hello John and Nate. first John I looked at your profile and am so using your first name. Ron always encouraged us to use our real names here, I think it's a good idea too.

I'm only aquainted w/ the vaunted RX7 by way of working on one over 10 years ago, I did some brief work on a bad carb. base gasket I think it was. I of course drove it around my old shop and it was a real kick to drive, loads of power wanted to rev to the Moon! But I have no real knowledge of these. A good view of the carb would enable opinions of it's Groove-ability. I am unsure of the end results on this engine, someone needs to try it. In addition to the known Groove effects on power, emissions and MPG's it would be useful to see if the exhaust temps would drop, as it has been demonstrated to be the case on other vehicles. That could indicate greater efficiency.

As a further thought- if the stock carb. is troublesome to Groove, I wonder if there is a conversion available like a Weber kit? This (at least the one I worked on)is a 4-bbl, extremely unusual for a Japanese car. We know the Weber DGEV is a great Groove candidate, but this idea would require research, also into the emissions inspection issue, if that applies. Commonly available 4-BBL replacement carb's are prob. too big for this engine?

John if you do get this RX7 we'd love to see more on it! And- Welcome to GadgetmanLand BTW! Are ya lookin' at Grooving anything else? I asked if you were from Down Under 'cause you referred to the "carby" that's usual parlance down There!

Nate thanks for digging up that vid. on the Wankel engine, that guy has a good idea I think! Do you mean overall engine cooling or just exhaust temps? Not sure but I bet these cars are hard on the Cat's and exhaust system.

Tracy G

Cooling in general.

This site's focus is mainly on the rotary in aircraft but there is some good information and lots of custom fabrication on this site.
http://www.rotaryeng.net

Nate thanks for that link on Wankel engine development. Jeepers I've never stuck my melon into the world of rotorary engine development, there's some serious stuff in that link! Last night I did a simple google search for RX7 carburetor conversion . Boy was I wrong evidently folks have done lots of conversions, even found discussions of going to injection, even from carb. to inj., and back to carb! Well I guess there's no limit to how much $$ one can spend...

Also I didn't realize that the RX7 doesn't have valves- Wow it feels like I'm totally ignorant on these motors. Amazingly simple. Kinda looks like they can be pricey to deal with, and fewer of 'em around. Slightly obscure, never seen discussion of one being Grooved. I don't see why the Groove wouldn't work, a matter of what carb. or TB is involved. Sounds like they are notorious for poor economy. They must be capable of swallowing tons of air/liter of displacement, and they DO rev like crazy. Must be why I see pics/info of American 4-BBL carb's and Weber sidedraft carb's too.

John, what year RX7 are you lookin' at? Would this be a budget find/build for you? I do remember being quite amazed to see a Japanese 4BBL carb on the only one I ever touched, I didn't open it up. The kid who owned it was real broke just wanted it to run so he could sell. But I Think I saw an iron base TB casting on it. If the one you're looking at is an iron TB, that raises issues for bit wear.

Grooving is a sort of "tuning" practice- when doing a carb., it is good to be able to re-tune said carb. Therefore it's good to have a carb that can be tuned-issue of availability of jets, rods, etc. I don't know if these Japanese $tock carb's have any part$ available other than rebuild kit$$. See my point? I ran into all this when I Grooved the stock 2BBL carb on my Subie, finally converted to Weber 32/36 DGEV. Much better!

Then there is the issue of cooling on these Wankel RX7 engines. They might run a rich mixture just to assist in cooling, using excess fuel for cooling. That's a discussion in of itself- I wonder if Grooving a replacement carb that is tuneable, and adding Plasma Jet Ignition, can give real benefits to these engines? A slightly Deranged mind wonders? Guys- talk to your RX7 owning freinds if you know any, see what they think. I bet nobody has proposed what I just did.

Back on topic...John take a closer look at this Mazda, see what's in there.

Tracy G