auxilary Posted October 9, 2004 Share Posted October 9, 2004 low power na rotaries last a long time. high powered turbo and na rotaries, don't last as long Quote Link to comment Share on other sites More sharing options...
NZeder Posted October 10, 2004 Author Share Posted October 10, 2004 Yep heard the 100k thing before also, and like Aux states usually turbo and high output (revs) NA's. I will be building the 4 rota for reliability not out and out performance. If I did the performance thing I would be getting close to 650hp from the NA 4 rota. Going for more standard street porting = results in longer life and around the 350-400hp area (only time will tell once I start the build and get it on the dyno etc). This HP can delivered by 13B TT with lots of work but life will be short if revs are high (9000 rpm) this type of engine might need to be striped and looked at every 3000k (assumes a race engine under race conditions) Quote Link to comment Share on other sites More sharing options...
auxilary Posted October 10, 2004 Share Posted October 10, 2004 wouldn't it just be easier to find a 3 rotor, port it, put in series 5 stationary gears and high comp. n/a rotors with 3mm seals, and run reliable 350 n/a hp? it'd still be cheaper than a 4 rotor. Quote Link to comment Share on other sites More sharing options...
NZeder Posted October 10, 2004 Author Share Posted October 10, 2004 Yes I could do the 20B install. A 3 rota will be around (all $$ in my local currency NZD) $4500-$6000 then a rebuild $7000 (includes all parts new balance as you state Series V n/a rota etc). Now given that 3 rota's are TT then I will need a custom intake manifold + EFI bits and computer etc. The difference between a 3 rota and the 4 rota kit is about $3000 then there will the difference in the rebuild. So the difference will be in the order of $10,000 but the result will be a unique Z or even Rota for that matter. And building this over 12-18months will help with the $$ differences. Yes I could go and fit a 3 rota in a month of so...but in 12mths I will have a very special car. Still $10,000 is a lot of money in any currency. So once the bike sells I will be looking into the cost of the 3 rota vs 4 rota in a lot more detail...... Quote Link to comment Share on other sites More sharing options...
Owen Posted October 11, 2004 Share Posted October 11, 2004 low power na rotaries last a long time. high powered turbo and na rotaries, don't last as long Exactly, plus add someone who does a DIY boost control and cranks it up or bolts on a new turbo and then blows it all up. But with the newer generation apex seals that problem is lessened isn't it? The latest thing I've seen is a sort of spring (a flat piece of metal bent into a U shape) which sits under the apex seal and keeps it pressed against the walls. Owen Quote Link to comment Share on other sites More sharing options...
Guest crayZ Posted October 12, 2004 Share Posted October 12, 2004 Just a side thought for a moment, anyone thought about gas rotaries? how much power difference are we talking about if you are going to opt for gas instead of petrol? I would like to see gas rotaries producing equivalent power (preferrably) or maybe less but not too much. Obviously more power is better.. Quote Link to comment Share on other sites More sharing options...
lazycyril Posted October 14, 2004 Share Posted October 14, 2004 Also remember to factor into your costs, that you will want a big 3 inch or so complete stainless steel exhuast system. Plus prolly some shielding. Rotoary exhuast is friggin HOT. I had a first gen beater rx7 for awhile, lotsa miles on it. it had less and less power over time, but was fairly reliable. Was fun little car to throw sideways at whim and with those skinny little tires on it and the moutain roads I commuted.... Wish first gens were smog exempt in Cali, no chance of that happening though Might make for an interesting electric car conversion. Hmm Z car with spare tire and fuel tank area converted into battery storage might work as well. Quote Link to comment Share on other sites More sharing options...
73240ZT Posted October 23, 2004 Share Posted October 23, 2004 I own a 1985 GSLSE RX7 with 135,000 miles, all original engine etc. Reving to 7000 rpm with no problems, if the engine is not overheated or over revved and has a clean supply of oil, it will last a long time. My two favorite engines are the free reving ROTARY and the sweet straight six. Kenny Quote Link to comment Share on other sites More sharing options...
Guest Turbo_20B_Luv Posted March 10, 2005 Share Posted March 10, 2005 Rotaries are very finicky, but its all in the tuning and in the cooling system. I wouldnt go 4 rotor for 2 reasons: Cost and Weight. VERY EXPENSIVE The best would be a 20B three rotor. They came in 1993 and up cosmos (depsite the fact that i keep seeing people say they are 1998 and up). It was an OPTIONAL motor, the 13B-RE was the "base" motor for those cars. Everyone that has put a high power turbo 20B into their Rx7s describes the driving experience with one word: "frightening". I shipped one once after wiring up engine management for it, shippin weight was 411 lbs with everything on the motor except for emissions/power steering/ac. In a 2800lb Rx7 (1993-1995 here in the states) with 550+ hp to the wheels, the car will break loose cruising down the highway at 70mph if you drop a gear and stomp on it. Heres a couple links to get you thinking... http://www.pettitracing.com/rx7/index.htm go to the "banzai" car in the above site. This car still uses the stock twin turbos! http://www.rx7club.com/showthread.php?t=293958&highlight=dyno if you are a HP junkie, the above link will make you happy... Quote Link to comment Share on other sites More sharing options...
Guest PaulfromPA Posted March 14, 2005 Share Posted March 14, 2005 Sounds like a very interesting swap!! If you like I have a video of a 4 rotor 3rd generation rx-7 at the dragstrip that I could send you. Let me know your email and I'll send it to you or just email me at sorgere@gmail.com. Paul Quote Link to comment Share on other sites More sharing options...
TomsCoupe Posted March 15, 2005 Share Posted March 15, 2005 I hope you have like $60k+ for a 4 rotor Quote Link to comment Share on other sites More sharing options...
crazy280 Posted March 15, 2005 Share Posted March 15, 2005 well, pushrod design IS newer than DOHC design. Food for thought. Pushrod design also has less moving parts, ergo less things prone to fail I don't mean to be arguementative here, but I think dohc is less prone to fail, especially if you're revving the engine. The whole valvetrain is much smoother, and generates less friction and heat. I'm not knocking pushrod engines, they're still one of the best performance options, I'm just clarifying. Quote Link to comment Share on other sites More sharing options...
auxilary Posted March 15, 2005 Share Posted March 15, 2005 from a daily driver perspective... if both motors were developed, let's say... by honda, for daily driving use, not designed to be raced, exceed 5000rpm, etc... pushrod design would be more reliable. Quote Link to comment Share on other sites More sharing options...
johnc Posted March 15, 2005 Share Posted March 15, 2005 Funny, I'm putting a 20B into a customer's FD right now. Quote Link to comment Share on other sites More sharing options...
auxilary Posted March 16, 2005 Share Posted March 16, 2005 you hiring? Quote Link to comment Share on other sites More sharing options...
johnc Posted March 16, 2005 Share Posted March 16, 2005 Not with the workmen's comp issues California has... Quote Link to comment Share on other sites More sharing options...
auxilary Posted March 16, 2005 Share Posted March 16, 2005 so you're saying you have illegal workforce from down south employed at your shop? Quote Link to comment Share on other sites More sharing options...
crazy280 Posted March 16, 2005 Share Posted March 16, 2005 from a daily driver perspective... if both motors were developed, let's say... by honda, for daily driving use, not designed to be raced, exceed 5000rpm, etc... pushrod design would be more reliable. Honestly, in that situation, I don't think the valvetrain design would make a huge impact. The only thing really wearing out in those circumstances are the valves and guides, which would wear out the same with either configuration. But it's funny you mentioned Honda, because they don't use ohv on any of their newer cars, to my knowledge, even cars that fit your criteria. Even GM and Dodge/Chrysler (the last to really hold on to ohv) are retooling for ohc/dohc on most of their cars (except the performance beasts like 'vette/viper/hemis - awsome cars that aren't really about reliability). Why would they be phasing out ohv on their daily drivers if it were more reliable? This was just my train of thought, and I'm no engineer, so I could be wrong. Edit: sorry, not trying to hijack this thread... Quote Link to comment Share on other sites More sharing options...
zed240au Posted March 16, 2005 Share Posted March 16, 2005 luv the sound of a 4 rotor and agree it would be awsome but and if you can afford it go for it but if moneys an issue go a 20b would be much easier and way cheaper Ive been rallying a rx4 with 13b j port motor for 6 years never touched the motor since rebuilding it plenty hp cheap and easy to look after though it does luv clutches would be on my third now and the ceramic race clutches car is competive with wrx v8s Think its how you look after them that counts always warm before reving dont rev over 9300 or they will twist cranks had a cousin got 160,000 mile out of a rx3 12a never touched it used to start it up have breafest then go to work mick Quote Link to comment Share on other sites More sharing options...
johnc Posted March 16, 2005 Share Posted March 16, 2005 Even GM and Dodge/Chrysler (the last to really hold on to ohv) are retooling for ohc/dohc on most of their cars (except the performance beasts like 'vette/viper/hemis - awsome cars that aren't really about reliability). Why would they be phasing out ohv on their daily drivers if it were more reliable? The reason why auto manufacturers are moving to DOHC over pushrod designs has to do with valve layout (3 & 4 valve vs. 2 valve). The cost benefits of a pushrod engine goes away when you're trying activate more then 2 valves in the combustion chamber. Quote Link to comment Share on other sites More sharing options...
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