Renesis Engine

[Guest Magnum Rockwilder]

Okay, I just had to "check" you since you "BS'd" me. LOL!

 

The reasons I hate rotaries are simple: I like power, reliability, and economy, all of which can be accomplished easily with a piston engine. Rotaries are great to sit around and marvel over, but no so great in actual functionality.

[MrWOT]

I look at in terms of power output to displacement.

 

At 1.3L the 13b can push a reliable 300hp and still be daily driven, that's about 231hp/liter. My 3S-GTE (2L) in my celica would be pretty hard pressed to live a long life at those kinds of levels comparitively since with the sane hp/liter output that would be 461hp. 8) For higher power a larger engine would be much better suited though, for said reasons of longevity and reliability that you stated. But for performance around 300hp the 13b should last.

 

So how do the 7's handle with the V8's in them? Understeer at all? I can just imagine what it must be like to drive a 7 with an LS1 under the hood

[Guest Magnum Rockwilder]

The displacement of the 12A/13b is arguable. I won't get into a long discussion over it because I've done it many times before, but in simple terms: Mazda chose to only count one combustion chamber per rotor towards the displacement when there are actually 3 combustion chambers per rotor.

 

The RX7's don't gain any weight with a well engineered SBC/SBF conversion. They gain about 125lbs with al all-iron Chevy engine, and an aluminum intake, heads, radiator, and water pump take it down to stock weight. With an aluminum driveshaft, lightweight exhaust, lightweight battery (Dynabatt, 13lbs), and other mods you can get them down to below stock weight.

 

There are quite a few V8 RX7's kicking ass in Solo II auto-x courses across the country.

 

Check out GrannysSpeedShop.com for all the info you need.

 

I have a V8 kit for a 1st gen RX7 for sale right now.

[Guest Magnum Rockwilder]

Oh, and who gives a #### how many liters it is, HP is HP, right? They can brag all they want about 300hp 1.3 liter engines, but they'll still get stomped by a basic bolt-on SBC.

[auxilary]

here's a simple break down:

 

how often do you change the timing belt on a 4 banger? hondas and toyotas are every 60k miles. What happens when you don't replace the timing belt at recommended maintenance window, and it breaks on you later?

 

right. you find out that the honda and toyota motors are indeed interference motors, and wind up with bent valves and dinged pistons.

 

Ever thought that this might apply to a rotary as well? But since the rotary has no timing belt, valves, cams or pistons... deep rotary maintenance is to pull it apart, inspect, replace parts as necessary. basically a rebuild.

[TomsCoupe]

my 12a ran 260k kms before it died. The only reason it dies was because i beat the living shit out of it and accidentally let the oil run EXTREMELY low. Rotaries are awesome engines. Infact, my next project will be rotary powered

[MrWOT]

here's a simple break down:

 

how often do you change the timing belt on a 4 banger? hondas and toyotas are every 60k miles. What happens when you don't replace the timing belt at recommended maintenance window' date=' and it breaks on you later?

 

right. you find out that the honda and toyota motors are indeed interference motors, and wind up with bent valves and dinged pistons.

 

Ever thought that this might apply to a rotary as well? But since the rotary has no timing belt, valves, cams or pistons... deep rotary maintenance is to pull it apart, inspect, replace parts as necessary. basically a rebuild.[/quote']

 

Hey now.. in defense, my 3S is non interference 8) Bag on Hondas all you like, but leave Toyota out of this

[auxilary]

toyotas aren't THAT wonderful. 96-2001 4 banger camries that everyone and their mom praises for reliability have a huge problem with timing belt slipping on the water pump and bending some valves

[Zhadman]

...but instead we'll just have to rely on the oh-so-subtle evidence that 99% of RX7's are on their 2nd, 3rd, or 4th engine due to failed apex seals.

 

Er... my 88 TII had over 100k miles on it's stock, original and never re-built motor. It was very well maintained and affectionately cared for by the PO and myself. ANY engine, wheter it has rotors or pistons, will fail under prolonged abuse.

[BrandonsZ]

Point well taken, I know they don't have "cylinders" I was dreaming of a reasonable way to make 8 rotor. so it would be like a v16? I guess? Ok so you can double the litres too that makes sence, so the 1.3L is really like a 2.6L 4 banger? So the 2.0 would be like a 4.0. I was totally off base, sorry.

 

So I guess 4-rotor would be reasonable, but I really can't fathom putting a 2 rotor 20B in a Z. I know they're cool and fast but...

 

I have nothing to base these comments on, I'm just shooting the breeze.

 

So what could you get for 20MPG? Probably a B20 if it was set up right, but you could have had a V8.

 

Really though you can't beat the Rotary for power density unless you go turbine, but then again the gas mileage could be measured in gallons per mile at that point.

 

So for the lightest possible engine with the most power and you don't care about gas mileage then it makes sence to go rotary. But in a Z? I just can't...

[auxilary]

Point well taken, I know they don't have "cylinders" I was dreaming of a reasonable way to make 8 rotor. so it would be like a v16? I guess? Ok so you can double the litres too that makes sence, so the 1.3L is really like a 2.6L 4 banger? So the 2.0 would be like a 4.0. I was totally off base, sorry.

http://www.howstuffworks.com and type in ROTARY ENGINE into the search field.

 

So I guess 4-rotor would be reasonable, but I really can't fathom putting a 2 rotor 20B in a Z. I know they're cool and fast but...

3 rotor. Each rotor is 650cc. You've also never driven a rotary.

 

I have nothing to base these comments on, I'm just shooting the breeze.

Exactly. No offense, but because of that you come off very ignorant.

 

So what could you get for 20MPG? Probably a B20 if it was set up right, but you could have had a V8.

How many people here set up a hybridZ for fuel economy? I know of only 1 person, and he's doing an electric powered Z, because that's his specialty. B20 is a honda motor found in the CR-V. 20B can do 20mpg in stock form. if you don't go over 2k rpm.

 

So for the lightest possible engine with the most power and you don't care about gas mileage then it makes sence to go rotary. But in a Z? I just can't...

Here, I'll solve that problem for you:

 

 

 

I mean, who in their right mind would want that kind of weight distribution and 2100lb weight in full trim!?!?!?!? Not me!

[NZeder]

In the late 60's early 70's Nissan/Datsun purchased a rotary license from NSU for the Wankel Engine and installed a prototype 2 rotor into a Datsun 1200 (this is a common engine swap for the 1200 today as drag cars - however there are more and more SR20DET getting installed in the 1200's now)

 

There were a lot of car manufactures looking at the rotary in the 70's, Merc, Nissan, Mazda, NSU (dropped when purchased by Audi), GM the list goes on. But the fuel crisis of the 70's almost killed the rotary off it was only due to Mazda's efforts/perseverance that we still have them on the roads today.

 

So if the fuel crisis did not happen it could be conceivable that a Z might have had a rotary engine as an option? Mazda has, over the years, killed all reasons to hate the rotary (IMO), reliability, fuel economy by competing in endurance races around the world. I guess this is another reason why rotaries are banned from most races and if they are allowed to run, some class rules stop the use of the peripheral port.

 

I guess there will always be the love 'm' hate 'm' with the rotary.

 

Re an 8 rota - WOW technically this would be very difficult to do as a rotary does not have split bearing like a piston engine. This makes assembly tricky and hence the reason for 3 and 4 rota to have a 2 or 3 piece eccentric shaft.

 

Cheers

Mike

[Guest Z2nr]

I have done a tremendous amount of research on a lot of import engines from the 1jz, 2jz, 3sgte, 13b, sr20 etc...

 

All of them have their weaknesses, but the 13b-rew has a bunch. The sequential turbos are a bird’s nest of vacuum lines which are prone to cracking, The rew engine also has a poor coolant system with a small radiator and an air separation tank which is prone to cracking. Another problem with them is the ecu that comes with the 3rd it is not very good. Unlike most piston engine cars that compensate for basic bolt-ons, the rew ecu does not do that, so any bolt-ons that increase air flow cause the engine to run in a lean condition. The apex seals on the rotors are very prone to failure because of this.

 

 

What people need to understand is that the rotary engine design has an inherent flaw. The rotor only comes in contact with the epitrochoid shaped housing, at each of the 3 apex seals. The engine does not have oil squirters or a crank to dip into the oil like a piston engine uses to stay cool, also rotors see heat at every side, where as a piston only sees the combustion on one side. All of these things makes for a very hot environment which is very bad for the weak apex seals. Not to metion that the engine is turbo charged which also generates a great amount of heat, IMO this is a recipe for disaster if adequate cooling precautions are not made.

 

Putting on any bolt on to enhance air flow, without appropriate dyno tuning will result in a blown motor, even something as simple as an intake or exhaust. It's not a 2jz where you just put on the parts change the oil add fuel and enjoy the added horsepower. The rew needs stringent tuning to be safe reliably.

 

The construction of the rew is not bad really, but the apex seals are a PITA. They are weak and extremely sensitive to detonation, a hard knock or ping and there goes an apex seal.

 

The 13b-rew is a great motor that needs the TLC of a mechanic with spare time. I think it is ridiculous to have to get new apex seals every 80k, that is retarded. That is like saying you need new piston rings every 80k, it is a hell of a job to do every 80k, changing a timing belt is a lot less time

consuming.

 

I personally think that for the package the 13b rew is a great engine, even though it would never be my personal choice, they are too delicate for schedule and driving style. A rotary engine is something that you keep stock or you modify it for on track use with sparing joy riding IMO.

[auxilary]

the rotary is a hell of a lot simpler to assemble/disassemble than a piston motor. The REW's biggest problem was heat because of the US emissions and catalytic converters. This caused a huge backlog of heat, which in turn dried up vaccuum lines (which is why common modifications are silicon lines and efini y-pipe, which is metal instead of plastic that's prone to cracking). These are more along the lines of safety modifications.

 

I am using a 13b-re. I am not using the stock ECU, I'm not using the stock twin turbos, and I have no exhaust restrictions. In fact, my exhaust is 3" all the way back, no cats, and a muffler that's a straight through design. Sure, it's loud and obnoxious, but it's freeflowing

 

The RE motor is basically a cross between the REW and 13b-t from FC rx7s. The intake ports are 30% bigger, and exhaust ports are a bit smaller to produce more torque. My fuel is converted to a parallel 6an system with a 255lph fuel pump and 1680cc secondary injectors.

 

Point is, sure, it has flaws, but as long as the owner knows the good and the bad, and knows how to avoid dealing with the bad, it's not a problem. I think my conversion will be just fine and dandy if it blows, great, I'll have a reason to do a street port and take out those annoying restrictive exhaust sleeves

[BrandonsZ]

But really... so testy.

 

Certainly I know nothing but the basics about rotary, I drove three, one was in a mazda pickup (my uncle's) it was the dog of all dogs, then I also drove both a 1980 and a 1986 mazda RX7, (they were owned by a good friend) the 1980 was the 1.1L and the 1986 was the 1.3L (i think). The 1980 was a little faster than a 323 IMO, the 1986 was pretty quick and had a nice top end, and a surprising amount of low end kick off the line. But my 5100lb Cadilac kicked his stock butt. When it hit 120K it blew something wouldn't idle and had shavings in the oil, he drove it in that condition for about 4 more months and surprisingly it hung together. then he hit a street sign and sold it for $500 in 1994.

 

However, it sounds like you have it all worked out, so in your case (aux) it will probably be bad ass! Good luck. Also it sounded like a jet engine and you felt like you had to plug your ears on the freeway when he floored it.

[auxilary]

1980 had a carbed 12a 1.2 liter na motor, in 85 the gsl-se rx7 had a 13b fuel injected motor, last year for first gen body style. 85 yielded new body style, 86-88 had optional turbo2 making 180hp, 89-91 was revised 2nd generation (labeled series 5) that had GXL, SE, GTU, GTUs, TurboII models. Turbo IIs had 200hp.

 

mazdas rotary cars are not under powered. They're perfectly balanced for handling. Try driving a miata - sure, it's balls slow, but it carves corners like crazy. Same goes for rx7s and the new rx8

[Guest Magnum Rockwilder]

The 12A is 1.1L.

 

...and for those interested, here's a site that explains that an RX7 engine should be rated at 2.6L instead of 1.3L:

 

http://www.turborx7.com/faqs.htm

[auxilary]

1146cc, 573 x 2 rotors. We should also stop calling the 5.0 mustang motor the 5.0, since it's technically 4.9 liters.

[Guest Magnum Rockwilder]

Agreed.

[(goldfish)]

Was I reading that right? Are they comparing the engines by how much volume is under combustion? The proper way would be to take the volume of the oval and subtract the rotors disp. IMHO.