Lotus Elan

Rotary swap

PostPost by: benymazz » Tue Feb 11, 2020 4:37 am

I imagine at least some members of this forums are familiar with Wankel (more commonly known as rotary) engines. Mazda made them mainstream in the 1970s and 1980s before their effective ban in racing ultimately led to their demise in production cars (kind of hard to do R&D without being able to race them).

Anyways, rotaries are known for being able to extract a good amount of power from a small amount of available space, and having a good hp/wt ratio as well. So I find myself pondering if it's possible to shoehorn a 13B rotary into an Elan...

If I ever find myself with an "extra" Elan somewhere down the road, this is probably something I will try.
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PostPost by: 2cams70 » Tue Feb 11, 2020 5:54 am

benymazz wrote: their effective ban in racing ultimately led to their demise in production cars (kind of hard to do R&D without being able to race them).


No it wasn't due to that:
1. Poor fuel consumption
2. Poor emissions
3. Poor reliability.

Mazda never properly resolved these issues inherent in the design.
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PostPost by: benymazz » Tue Feb 11, 2020 8:02 am

2cams70 wrote:
benymazz wrote: their effective ban in racing ultimately led to their demise in production cars (kind of hard to do R&D without being able to race them).


No it wasn't due to that:
1. Poor fuel consumption
2. Poor emissions
3. Poor reliability.

Mazda never properly resolved these issues inherent in the design.


You’re right - these are important details I left out. My take on the situation is that at the time the 787B ran, Mazda had been using their race cars as a test bed for the latest engine technology they were developing (as many manufacturer-associated racing teams do). Maybe they were going down a path that would eventually lead to a dead end, but as long as it was still winning races they were willing to do it. Once the rotary was phased out of racing, combined with increasing emissions regulations and reliability problems that were becoming more pronounced as cars in general were becoming more reliable while the rotaries still had maintenance issues, the rotary was dead.

Mazda’s sales of cars with rotary engines as a percentage of total sales were also falling rapidly at this point and combined with the situation outlined above (a higher cost to make an engine that could be used in a production car) it’s not hard to see why they pulled the plug on it.
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PostPost by: el-saturn » Tue Feb 11, 2020 2:21 pm

a friend of ours has a europa s2 with a rx7 engine in it - the workmanship and design of the rear is awful: the mazda bits and the lotus bits are in a JOINT VENTURE - colin would kill the guy!! ...... BUT he's got about 140hp and he's f... quick! only this lotus 11 was quicker at hockenheim a few months ago...... sandy
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PostPost by: Davidb » Tue Feb 11, 2020 4:55 pm

I recently noticed that Mazda RX8s can be a very good deal so I spent a lot of time reading up on them since I have always thought they were attractive. It seems that Mazda made some changes to the rotary engine they fitted in the RX8 to try and meet emission regulations. The engines as used in the RX8 are far less reliable as a result I learned. "How difficult/expensive can it be to overhaul a silly rotary engine?" I thought. The answer is Very, on both counts. The rotors and housings have to be replaced at least. Buy a replacement engine from Mazda? They will only offer a warranty if a Mazda dealer installs it. Big bucks. I decided to admire them from afar... Mazda built a plant in N.America to rebuild the engines replaced under warranty since there were so many to replace. The engines produced there were not acceptable so they transferred the rebuilds to Japan--shipping costs added enormously to the cost of replacement engines.

They must have lost a ton of money. That is maybe why they don't make rotary engines anymore!
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PostPost by: Donels » Tue Feb 11, 2020 8:51 pm

I've seen a couple of Lotus 7's converted to rotary engines, they were called 'rotus' so an Elan must be possible. Whether it’s desirable or not is a different question.
Fundamentally the wankel failed because the combustion chamber is the wrong shape, being long and thin. The ideal shape is spherical. The long thin shape causes high heat loss through the combustion chamber walls giving high fuel consumption and the 'cool' walls quench the combustion giving high emissions.
Last edited by Donels on Wed Feb 12, 2020 8:28 am, edited 1 time in total.
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PostPost by: Davidb » Tue Feb 11, 2020 9:46 pm

Donels: Not to be persickety but, The Rotus (notice capitalised) was a Lotus Seven replica built in the USA in the eighties by a Toyota dealer that used Toyota drive train components. The suspension was also modified using a "rocking arm" front suspension designed by a contemporary racing designer-ferfget his name... The name "Rotus" came about apparently because of the way the Japanese Toyota representatives pronounced "Lotus". I got that from the son of the Toyota dealer.
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PostPost by: types26/36 » Tue Feb 11, 2020 10:14 pm

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PostPost by: The Veg » Wed Feb 12, 2020 3:11 am

Interesting timing- the podcast I co-host Just released an episode with much talk of Mazda rotary engines:

https://storage.pinecast.net/podcasts/7 ... _Ep_04.m4a
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