Rotary Elite

[bradltl]

As I am making slow progress on my build, the consideration of engines has come up. I've moved away from a V8, just being too heavy for the chassis and too much torque for the drivetrain components. My next consideration was to put in a rotary, specifically a 13b turbo2. Then I found this:

Do you happen to be on this forum? If not, does anyone know this person / car? I would love to know more about the build!

Thanks!

[lotect]

Hi Brad from memory I'd have thought the rotary engine was quite heavy compared to a modern v8. It's also extremely thirsty.

Good luck

[bradltl]

The Mazda Rotary (13b) weighs in at about 122kg or 247lbs. The Chevy L98 (Corvette) engine comes in at 270.5kg or 596lbs.

I haven't personally weighed either of them, but that is what the internets tells me.

[lotect]

I stand corrected it's been a long time since I handled one I just remember being surprised how heavy it was.

Cheers Alan

[DanR]

Make sure you have space for the gearbox. The crank line of the rotary maybe higher than what was there originally.

[Herc]

..the gearshift ended up a long way back, a bit like '70s TVRs. Not sure I'd enjoy that much.

Also am curious if the rotary has much benefit over the Lotus 2L. I was under the impression that that were high revving with poor low end torque too.

Herc

[Dunc]

Are those weights for the iron LT series Chev V8?

The later alloy LS series are reputed to be super light and powerful.

The 4.6 from the Range Rover is only 20Kg more than a 907, and the same if the 907 has A/C fitted.

Another option would be the Northstar engine (which I think is similar to the later OHC LT5) and would be available cheaply.

D

[bradltl]

That weight was from the cast iron block... from my research the aluminum block saves about 100kg.

I need a complete engine and transmission for about 800USD. My build is based on challenge with a set maximum budget, so I am a bit limited in what can be afforded in that space. The last time I priced Northstars, they were running 1100-1500.

The thought behind using the rotary is specifically the low torque number. That should minimize the shock load on the drivetrain components while still being able to provide good power. Certainly not ideal, and I'm not married to the engine either, but for the goals of my build and the restrictions of the challenge, I can't think of a better alternative.

[lostcause]

The later rotary engines are reliable, very powerful and super compact, the accessories take up more room than the lump itself! The revvy nature of the rotary and its high rpm limit will suit the low ratio axle of the elite far better than a lazy v8, remember the original engine does 7000rpm, most v8s are out of puff by 5-5500. I'd give the rotary a big thumbs up.

[frommerstop]

I used to work for Mazda in the early eighties, I'm a big fan of rotaries, having built & raced them over the years (even taught a service class for dealer technicians back in the day), so I've seen a few project Rotary engined Lotus being built over the years, but most were Europas, and at least one I've seen was in an Elan. The one I read about on an Elite had issues with the shifter location, as has been mentioned, but I suppose you could adapt the Lotus bell housing to fit rather than use the Mazda 5spd as that guy did. In a Europa, the rotary works very well... but then it was only replacing an old Renault engine! As for cost & weight, I think you're better off with a 4.0L Rover with a low profile Edlelbrock (spl?) manifold & Holley... it weighs 12lbs LESS than the stock 907 engine, and the cost less on the used market than a good 13b. $800 is a very tight budget though, I'm not sure you could do either one for under a $1500 by the time you factor in hoses, mounts, carb&manifold, exhaust, and either new bell housing, or modifying the existing one. Also, if you don't get a "good" rotary, your rebuild options are limited. Very few people really know how to properly rebuild one, and parts are only offered through a couple of after market suppliers... Mazda will NOT sell you a gasket set, apex seals, corner seals or side seals, let alone a rotor or housing. Heck, you can't even get an oil pump from Mazda any more! If you need rebuild parts, you're left with cannibalization, or after market racing firms, like Racing Beat, or Rotary Engineering, and they are all too happy to charge you a premium for their "racing" parts.

$800 would go a long way towards "freshening" your 907, unless it's beyond hope though!

...just a bit of food for thought.

Cliff

[bradltl]

This is all I have of the 907...

[Steve Cook]

Doesn't the rotary spin in the opposite direction to most engines - or am I thinking of something else?

[frommerstop]

Wow, I guess even an $800 tune up won't do it!

Well, if you decide to go the Rover/Buick V8 route, you can use MG V8 headers, and there is a bell housing that will bolt it straight up to your Lotus 5spd. Unfortunately by the time you buy them (and the carb/manifold combo) you'll be at, or near a grand... and you'll still need a donor engine.

Cliff

Doesn't the rotary spin in the opposite direction to most engines - or am I thinking of something else?

No, the output is clock wise (from driver's position), as is industry standard. The rotor does spin counter-clock wise (anti-clock wise for you Brits), but it's center bearing acts against the eccentric shaft (the Wankel version of a crank), turning it the opposite direction.

Cliff

[bradltl]

Wow, I guess even an $800 tune up won't do it!

Yea, that is why I've been considering an engine swap since the beginning of the project.

I think we are pretty set on a Rotary swap at this point. Now it is really just a matter of which version. Ideally I would like to get a 13b turbo2, but we'll probably just end up with a '86 or later 13b(NA). Then port and tune it.

I would still love to get some information from that build video above. I sent a message via youtube, but have not received a response.

[frommerstop]

I think a non-turbo 13b is a good way to go, if you're set on rotary power. Turbos raise a bunch of issues, cooling, exhaust plumbing, under hood temps, etc. As for porting, that gets quite involved on a rotary, similarly with two strokes, it involves full engine tear down. Bridge porting is worth while if you're building a new engine, but not really something doable near your budget I'm afraid. I have considered such a conversion on a second Elite that I'm looking at picking up, I think if I do go the rotary route on that one, I'll try and adapt the bell housing of the stock Lotus 5spd to it. I really like the Mazda trans, but don't want the shifter under my arm pit! I'm thinking I could take the two bell housings, cut & weld, and make one doable piece... maybe you will "pave the way" with your project. I should mention, if you use a Mazda Wankel, you'll need a bit better radiator, and I'd add an oil cooler (like the first generation RX-7s used) under/in front of the radiator. More than 60% of a rotary's cooling is by oil inside the rotors, so keeping the oil temp in check is critical. Also, switching to Euro spec front bumper helps air flow considerably - looks way better as well!

Cliff

[bradltl]

you'll need a bit better radiator, and I'd add an oil cooler (like the first generation RX-7s used) under/in front of the radiator.

Got that one handled already. A good friend of mine, did a rotary swap into a Miata some years ago. Recently tore it down and sold off bits of it. He gave me this:

[frommerstop]

Could be a bit of a trick getting to that radiator cap!

[bradltl]

That is something that I hadn't considered!

[Artie]

The rotary in NA form will also last almost forever, although you will lack a little low end, you will make up for it up top! A well ported and fuel injected 13B 6 port will net you somewhere in the 220bhp to 230bhp, if done correctly. The engine doesn't take up much room as you've looked into and you can find the engine and trans in junkyards for probably $500 or so. Just be sure to refresh all the water seals and metal springs internally when you rebuild it, as they are critical to the engine sealing! Also, as mentioned, use a large oil cooler and I'd suggest synthetic oil, even though mazda recommends against it. I've been a Porsche Club of America and Audi Club of America driving instructor for over 10 years running my FD3S with a healthy raceported 13BREW engine and when pulled apart to refresh, there is no visible wear to any metal surfaces or bearings internally! The previous 13BREW I tracked for 4 years and ran conventional Valvoline oil had considerable wear on every surface and bearing! And remember, this is inside a raceported twin turbo engine that produces over 400 horsepower to the tires! I'm very intrigued with your project and will be checking often! Cheers!

Art

Edited August 10, 2011 by Artie

[bradltl]

I actually almost bought a 13B Turbo2 engine a couple weeks ago. We were settled on the price and I was about to make the deal when he dropped a bit of information that killed it. He didn't have any of the turbo components for the engine. It was a deal breaker.

If anyone has a line on a complete 13B engine and transmission, drop me a line.

[Artie]

You looking for a turboII or just an efi? I can probably find a non turbo and trans fairly easily. Turbo II may be tougher

[bradltl]

Really, either... I need a good deal (as this is a budget build). Ideally I would like a turbo2, but an efi would be good if the price and condition is right.

Turbos create their own issues, specifically with heat, but the added pep would be fun.

[Artie]

Turbo's do add some issues, however, the benefits far outweigh the risks in my opinion. I've owned 3 turbo rotary cars and 3 other twin turbo'd cars in the last 15 years, and to be quite honest, I only had 1 turbo failure and it was due to an improperly built set of remanufactured turbos for my current RX7 track car. The person I purchased the car from, had the turbos rebuilt by a diesel turbo builder and they used a pressed in fitted bushing instead of the dual stage floating bushings Hitachi uses in it's turbos so when I hit 18psi blasting down the front straight at Heartland Park Topeka's road course, The rotating assembly in the secondary turbo contacted the housing due to the bearing seizing the shaft! Anyway, a turbo'd rotary will easily make 300 reliable HP, but it will not be within your budget as posted unfortunately. I'll keep my eyes peeled for a donor motor for you and possibly trans.

Art

[bradltl]

Just bought the engine donor... ended up getting a 12A for a deal I couldn't refuse. Picking it up in a couple weeks, and by that point should have the Elite completely stripped.

Here was the PO's ad:

Early 80's RX7 - Silver

81/82/83?

Paint in decent shape.

I would recommend a flat-bed to get it home;

the engine can be made to reliably run in the short run, but as the 12A goes it is likely due for overhaul;

Peformance Parts:

Racing Beat components

Dellorto DHLA Carb with Racing Beat Performance Package consisting of:

intake manifold

exhaust header with tuned exhaust and tail pipe

dual Racing Beat fuel pumps,

springs and shocks.

Car has disc brakes on four wheels and BBS Alloy rims.

Car was originally restored inside and out with performance package for about $10,000.

Performance package is still worth about $1.000.

Junk value is $360 (2400 @ $13.60 cwt);

RX7 fans, don't let this car go to China smelters.

Make an offer.

This car is more than suitable for a restoration project, or, if you choose, as a racing project.

I am selling this car for my brother abroad, so please inquire via email for additional contact information;

Myself or my parents will be showing you this car, so please provide a full name and a phone number and I will do the same;

serious inquiries only.

$1000.00

• Location: Macon, GA
  
• it's NOT ok to contact this poster with services or other commercial interests
  

[Ozlotus1976]

This is my Three year pain in the you know what !

As obama has run the country into the ground i have had to slow down with the build

but am getting close to been on the road will have to save for body work and paint

i had to mod the frame for the extra HP thinking around 350 would like 400

the torks are low so the engine is a high reving computer set 9500 RPM

i had twin turbos but one was in very bad shape so put a GT45 T4 single Max 28 PSi

but running it at only 10 PSI

I'm running the rx7 tran and the stick has moved back about 6 inches this is nice !

custom drive line was made and later maybe taller gears in the diff i think it has 4.11 but not sure ???

the bushing and ball joints in the front are shot but i have got new stuff for them

Edited June 30, 2012 by Ozlotus1976