V6 - BAD! Rotary - Good?
Discussion
Has anyone out there seen or heard of an Elise being converted to Mazda rotary power? It seems like a natural 'fit', in several ways - lightweight(!),compact (easy fit), and Fast! A non-turbo late model Mazda mill should put out in excess of 175 BHP easily; not to mention the next generation "Rensis" motor - around 240 BHP at 9000 rpm, and it's even smaller and lighter than the current unit!
Has anyone out there seen or heard of an Elise being converted to Mazda rotary power? It seems like a natural 'fit', in several ways - lightweight(!),compact (easy fit), and Fast! A non-turbo late model Mazda mill should put out in excess of 175 BHP easily; not to mention the next generation "Rensis" motor - around 240 BHP at 9000 rpm, and it's even smaller and lighter than the current unit!
I've heard that UK petrol additives contribute to early wear for Apex seals (rotary equivalent to piston rings) and that it is unusual for them to last 100,000 miles. Then there's the economy... Not good considering the power output. Imagine driving a Lotus Elise and getting TVR mileage. The Elise's fuel tank isn't that big either.
I'm not sure what the ramifications would be for a tiny mid-engine car like the Elise. Rotaries need serious muffling. There is nothing quite so nasty as an improperly silenced Rotary engine.
Also, emissions on older engines can be a problem. Certainly they are far less environmentally friendly than any modern engine and there may be problems getting someone at the MOT to understand why a new car like an Elise is blowing so much unburnt fuel out the tail pipe.
Mazda claims to have addressed emission and economy concerns with the side-port design in the new engine. But, due to their small production quantities, prices are likely to be quite high for those who just want to buy an engine.
You've raised several good points here, but I think that the rotary has gotten sort of a "bad rap", in some ways: from what I read, the late-model engines have much better sealing than ones from more than about 5 years ago, but, more to the point, replacing the apex seals on a rotary should be a breeze, compared with rebuilding a piston engine - it's certainly much easier to remove, disassemble and re-install the engine itself. Parts are much cheaper, since there aren't many of them(!). I don't think that a properly rebuilt rotary would have undue trouble passing smog, assuming that the emissions gear is working. The engine is so much smaller than even a compact piston engine that there's more room for muffling (you're certainly right about badly silenced rotaries!), and there's still the basic point - you'd get a qualitative improvement in performance, due to the reduced weight and improved balance (lower polar moment, etc.), compared with a piston engine with comparable "numbers". An engine/transmissin package contributes a lot more to a car's performance than just supplying torque, and it's in a light, short-wheelbase car like an Elise that this type of improvement would be most significant, so I think that it would be worth some extra hassles. Yes, you're right about the gas mileage, but when you got your foot in it, it might be worth it - imagine the look on the Ferrari owners face...
Stephen White said: You've raised several good points here, but I think that the rotary has gotten sort of a "bad rap", in some ways: from what I read, the late-model engines have much better sealing than ones from more than about 5 years ago, but, more to the point, replacing the apex seals on a rotary should be a breeze, compared with rebuilding a piston engine - it's certainly much easier to remove, disassemble and re-install the engine itself. Parts are much cheaper, since there aren't many of them(!). I don't think that a properly rebuilt rotary would have undue trouble passing smog, assuming that the emissions gear is working. The engine is so much smaller than even a compact piston engine that there's more room for muffling (you're certainly right about badly silenced rotaries!), and there's still the basic point - you'd get a qualitative improvement in performance, due to the reduced weight and improved balance (lower polar moment, etc.), compared with a piston engine with comparable "numbers". An engine/transmissin package contributes a lot more to a car's performance than just supplying torque, and it's in a light, short-wheelbase car like an Elise that this type of improvement would be most significant, so I think that it would be worth some extra hassles. Yes, you're right about the gas mileage, but when you got your foot in it, it might be worth it - imagine the look on the Ferrari owners face...
Don't get me wrong, I love rotary engines. I've owned two RX-7s in my life and when I was younger, a friend of my dad's had an RX-3.
The seals haven't been a problem for engine reiability since the first RX-7s were introduced. However, I have read some articles that claim UK petrol additives caused serious premature wear. That, and the low mileage would probably explain the absurdly low prices for used RX7s in the UK market.
Regarding rebuilding rotary engines. I've never tried it myself although I've read a few books on the subject. The cost of normal replacement parts (assuming you haven't cracked either of the rotor housings) is pretty low. The time it takes to remove and disassemble the engine, clean and replace components, then put everything back together is also fairly low.
However, I've been told by people with lots of experience doing this that it is a fiddly job getting the new seals seated correctly and it is not uncommon for a rebuilt Wankel to need rebuilding again within 10k to 20k miles.
As far as size goes. Yes, in the 80s they were very small considering the power they put out (the amount of empty space under a mk I RX-7's bonnet is almost comedic). By today's standards, they have lost a surprising amount of ground in that regard. The 1.8l Rover K is probably larger but, if my memory serves, not by a whole lot. With Lotus' tweaks, the version in the 111s put out slightly more power than the normally-aspirated 13b engine used by the 1st and 2nd-generation RX-7 and revs almost as freely.
The new side-port rotary claims singificant increases in thermodynamic efficiency which both increases power and decreases emissions and fuel consumption. We'll see how it does when the RX-8 is released.
I have heard claims that with proper attention to intake, intercooling and exhaust, the twin-turbo version of the 13b can make well in excess of 350bhp without becoming unusable.
I would like to see an Elise with 300+bhp on tap. That would be a true Ferrari-frightener. You might even give the Pagani Zonda a scare.
There is a big problem with the Rotary engine.....
It goes the wrong way!
I thought about putting one in my atom, but by the time you have managed to switch the direction it was too wide to fit in.
I stuck witht he k series and got 290bhp, so if you want to have the power go and get it
It goes the wrong way!
I thought about putting one in my atom, but by the time you have managed to switch the direction it was too wide to fit in.
I stuck witht he k series and got 290bhp, so if you want to have the power go and get it
Yes, it's true that the twin-turbo RX-7s put out 350 to 400 BHP without becoming completely unreliable: Steve Millen has done some amazing things with them, for example. However, the news that they turn the wrong way is tragic. I recall that Honda motors also turn the "wrong way" - does that mean that a transaxle-transplant would also be in order? Whew! This is starting to sound like I'm getting my comeuppance - it had better "be worth some extra hassles"! Your point about the rebuilding being a 'fiddly job' also sounds quite credible, unfortunately. Oh well... Do you really think that a 300+ horse Elise would be fun to drive? Call me an old woman but, offhand, that just sounds scary-fast, not too much fun. Ah well, getting old, I guess...
I suppose that if one were going to transplant a reciprocating-engine into an Elise, one could do worse than an R-type Honda mill. Hmmm...
I suppose that if one were going to transplant a reciprocating-engine into an Elise, one could do worse than an R-type Honda mill. Hmmm...
Stephen White said: Yes, it's true that the twin-turbo RX-7s put out 350 to 400 BHP without becoming completely unreliable: Steve Millen has done some amazing things with them, for example. However, the news that they turn the wrong way is tragic. I recall that Honda motors also turn the "wrong way" - does that mean that a transaxle-transplant would also be in order? Whew! This is starting to sound like I'm getting my comeuppance - it had better "be worth some extra hassles"! Your point about the rebuilding being a 'fiddly job' also sounds quite credible, unfortunately. Oh well... Do you really think that a 300+ horse Elise would be fun to drive? Call me an old woman but, offhand, that just sounds scary-fast, not too much fun. Ah well, getting old, I guess...
I suppose that if one were going to transplant a reciprocating-engine into an Elise, one could do worse than an R-type Honda mill. Hmmm...
Having driven both an Elise and a Tuscan, I'm one of the sorts who believes that a little fear is a good thing. I love being in a car where I don't normally put the pedal all the way down because doing so would be a bad idea. So, I think an Elise withh 300bhp (or more) wouldn't necessarily be a bad thing. 400+ bhp/tonne is nice to have on tap.
The ordinary Elise just doesn't have the grunt it should have. When I drove it, I found myself flooring it way too often - and wanting more.
The perfect car (to me) would be the result of a joint venture between Lotus and TVR. A balanced combination of the best brute-force for which the Blackpool kids are famous along with the handling and finesse (and, lately, build quality) of the Norfolk crew.
Now, THAT would be a car worth having!
Regarding rebuilding of the rotary, having done it myself with the 13B in my 1st gen RX-7 I can confirm it is really simple. I had no particular problems and I've never rebuilt any engine before.
I'm seriously considering a rotary transplant into an early Esprit, would be a very nice combo I think. Would be long term as I have a couple other projects with higher priority (such as importing one of the first R32 Skylines into Canada and doing a bit of tuning on that).
The rotary would have some trouble going into an Elise as there are no factory transversely mounted applications thus no transaxles available. If the Honda motor turns the same way perhaps one could use a Honda transaxle. Another consideration is that the rotary's output shaft is in the centre of the engine, and therefore there is more engine below the output shaft than in a piston motor.
Regarding which version of the rotary to use I would vote for one that has yet to be released: the one in the new RX-7, which according to rumour will be about 280-300hp from about 1.5L displacement, non-turbo.
However as much of a fan of rotaries as I am I think putting one into an Elise would be considerably more trouble than it would be worth unless one were using a turbo version with the idea to build a 2/3 scale supercar that would be faster than any stock supercar.
Here is an interesting link on this subject:
www.wwwattmembers.co.uk/lotuslife/ubblotuslife/Forum11/HTML/001096.html
J
I'm seriously considering a rotary transplant into an early Esprit, would be a very nice combo I think. Would be long term as I have a couple other projects with higher priority (such as importing one of the first R32 Skylines into Canada and doing a bit of tuning on that).
The rotary would have some trouble going into an Elise as there are no factory transversely mounted applications thus no transaxles available. If the Honda motor turns the same way perhaps one could use a Honda transaxle. Another consideration is that the rotary's output shaft is in the centre of the engine, and therefore there is more engine below the output shaft than in a piston motor.
Regarding which version of the rotary to use I would vote for one that has yet to be released: the one in the new RX-7, which according to rumour will be about 280-300hp from about 1.5L displacement, non-turbo.
However as much of a fan of rotaries as I am I think putting one into an Elise would be considerably more trouble than it would be worth unless one were using a turbo version with the idea to build a 2/3 scale supercar that would be faster than any stock supercar.
Here is an interesting link on this subject:
www.wwwattmembers.co.uk/lotuslife/ubblotuslife/Forum11/HTML/001096.html
J
Johnny Freon said: Regarding rebuilding of the rotary, having done it myself with the 13B in my 1st gen RX-7 I can confirm it is really simple. I had no particular problems and I've never rebuilt any engine before.
I'm seriously considering a rotary transplant into an early Esprit, would be a very nice combo I think. Would be long term as I have a couple other projects with higher priority (such as importing one of the first R32 Skylines into Canada and doing a bit of tuning on that).
The rotary would have some trouble going into an Elise as there are no factory transversely mounted applications thus no transaxles available. If the Honda motor turns the same way perhaps one could use a Honda transaxle. Another consideration is that the rotary's output shaft is in the centre of the engine, and therefore there is more engine below the output shaft than in a piston motor.
Regarding which version of the rotary to use I would vote for one that has yet to be released: the one in the new RX-7, which according to rumour will be about 280-300hp from about 1.5L displacement, non-turbo.
However as much of a fan of rotaries as I am I think putting one into an Elise would be considerably more trouble than it would be worth unless one were using a turbo version with the idea to build a 2/3 scale supercar that would be faster than any stock supercar.
Here is an interesting link on this subject:
www.wwwattmembers.co.uk/lotuslife/ubblotuslife/Forum11/HTML/001096.html
J
But would you have to mount the engine transversely? A two-rotor engine (e.g. Mazda 13b) isn't much longer than it is wide as I recall. I think anyone wanting to mount one in an Elise would probably have to give up the Elise's boot but that isn't a big sacrifice.
Still, I agree with you in principle. I think someone who wants sphincter-puckering performance out of an Elise would be better served finding a hugely powerful 4-pot and transplanting that.
The Rotary engine sounds like a perfect choice for any Elise - especially the unit going to be used in the coming RX8 ( 1.3cc = 250bhp ! )
I think the main problem will be the heat generated from the engine, my understanding is that the engine can get upto some 30% hotter than a normal aspirated engine. So my fear would be for the car setting on fire....
Nice thought though.
SVG
>> Edited by Spinning-v-Grid on Friday 20th December 11:42
I think the main problem will be the heat generated from the engine, my understanding is that the engine can get upto some 30% hotter than a normal aspirated engine. So my fear would be for the car setting on fire....
Nice thought though.
SVG
>> Edited by Spinning-v-Grid on Friday 20th December 11:42
JonGwynne said:
But would you have to mount the engine transversely? A two-rotor engine (e.g. Mazda 13b) isn't much longer than it is wide as I recall. I think anyone wanting to mount one in an Elise would probably have to give up the Elise's boot but that isn't a big sacrifice.
True, true, hadn't thought of that. Then you could use something like a Boxster transaxle. Provided you didn't end up with 5 reverse gears and one forward . . .
Spinning-v-Grid said: The Rotary engine sounds like a perfect choice for any Elise - especially the unit going to be used in the coming RX8 ( 1.3cc = 250bhp ! )
I think the main problem will be the heat generated from the engine, my understanding is that the engine can get upto some 30% hotter than a normal aspirated engine. So my fear would be for the car setting on fire....
Nice thought though.
SVG
>> Edited by Spinning-v-Grid on Friday 20th December 11:42
I'd forgotted about the heat issue...
You're right not only do the rotaries run hot, they are also more sensitive to damage from overheating than piston engines.
With that in mind I'm not sure how practical a rotary lump would be in a rear-engined car, particularly one with as small an engine bay as the Elise and non-metallic body panels besides.
Next time you lift the bonnet on an RX7, take a look at the size of the radiator.
Now, try to imagine how you'd be able to put something with that cooling capacity in the nose of the Elise and then get the necessary flow-rate between the engine and radiator.
My Delorean had two big pipes (send and return) running the length of the car underneath. I assume the Elise has a similar arrangement but given the size of the car, can the pipes be big enough to handle the flow necessary to properly cool a rotary engine?
Say what you like about piston engines, they are pretty compact and efficient these days. Now if we can just get rid of these damn poppet valves. ;->
How about putting a new honda engine in out of the s2000.
They now go the right way
They are light
They rev to silly amounts
Deliver masses of power in basic trim
Worth a thought
Happy xmas all
Sorry about he web address, the cars not finished yet so I havent much to put on there yet.
Will have something there soon though
They now go the right way
They are light
They rev to silly amounts
Deliver masses of power in basic trim
Worth a thought
Happy xmas all
Sorry about he web address, the cars not finished yet so I havent much to put on there yet.
Will have something there soon though
atom290
It's already in the works. www.prototyperacing.com
To all,
The engine/trans out of a Formula Mazda is the easiest solution. Well sorted, 6 speed sequential box. They'll be doing developmental work on the Renesis engine this season, so by next year it'll be well sorted. It's also nice they're all built right here in So. Cal. I'll be paying them a visit soon.
It's already in the works. www.prototyperacing.com
To all,
The engine/trans out of a Formula Mazda is the easiest solution. Well sorted, 6 speed sequential box. They'll be doing developmental work on the Renesis engine this season, so by next year it'll be well sorted. It's also nice they're all built right here in So. Cal. I'll be paying them a visit soon.
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