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This might be a great donor car model

Posted: Sep 13 2017 5:00am
by helpfulguy
So I just read that cars with rotary engines/wankel engines require a lot of maintenance and break down a lot. Making the market full of good condition "useless" cars. Useless unless you want a perfect condition car, without ICE engine, for peanuts. Cool model Mazda RX8, I Googled "Mazda rx8 without engine" and found this for example (no affiliation), not sure there are any other models with similar engine:

https://www.salvageautosauction.com/mod ... 8-for-Sale

Re: This might be a great donor car model

Posted: Sep 13 2017 5:40am
by amberwolf
helpfulguy wrote:So I just read that cars with rotary engines/wankel engines require a lot of maintenance and break down a lot.
I dunno about that--a friend had an '87 RX-7, trouble-free (except for a mirror taken off by a pizza driver) from new off the lot almost a couple decades until someone with no license or insurance driving an unregistered car slammed full-speed into the back of the RX-7 while waitng at a red light. AFAIK he simply had the regular maintenance done per the schedules in the manual; he drove it quite a lot (he loved that car and still bemoans it's loss).

Re: This might be a great donor car model

Posted: Sep 13 2017 10:45pm
by The Toecutter
The 3rd generation RX7 from the 1990s has the lowest drag of the choices of used Mazda sportscar readily available. It will yield a decently efficient conversion that could give 15-20% better efficiency than a Nissan Leaf. The 1st generation is especially low in weight. You can't go wrong with any RX7 as a donor choice for a sports car conversion to electric.

The RX8 is less aerodynamic than all types of the RX7s, heavier than all types of the RX7s, and more complicated than all types of the RX7s.

Re: This might be a great donor car model

Posted: Sep 29 2017 2:06pm
by Drunkskunk
Mazda rotary engines are highly reliable. If mistreated, the engine can burn it's seals and need a repair, but the engine can go for hundreds of thousands of miles. They get a bad rep because they eat a quart of oil normally between changes, and are far from fuel efficient by displacement. I think it was Road and Track that said " All the power of a V8, and the gas mileage too! "


The RX-8 has better CD than the RX7. 0.30 for the RX8, 0.33 for the 3rd generation RX7. But the RX7 has a better CdA, 6.14 VS 6.44
(Source http://ecomodder.com/wiki/index.php/Veh ... _Drag_List)

Oddly, those are both way better than the tiny Mazda Miata at CD 0.38 and CdA 6.68. For it's size, that's practically the aerodynamics of a brick wall. My 2005 Dodge Durango Looks like a brick wall, but it has a CD of 0.39, and a CdA of something in the mid 8s. Often what looks Aerodynamic to the eye isn't to the wind, and vice versa.

An old Honda CRX HF has a CD of 0.29, and a CdA of 5.39

Re: This might be a great donor car model

Posted: Sep 29 2017 7:19pm
by maydaverave
If I was going to do a ev conversion car I would get a compact older car with no power steering or power brakes. Preferably rear will drive so I could just bolt a motor to the differential.

Re: This might be a great donor car model

Posted: Sep 29 2017 8:14pm
by Hillhater
Drunkskunk wrote:Mazda rotary engines are highly reliable. I....
.... They get a bad rep because they eat a quart of oil normally between changes, and are far from fuel efficient by displacement.
Actually, most current VW turbo motors use more oil than that !
And the fuel efficiency is a "furfy" ...the result of most motoring "experts" not understanding the actual "working" capacity of the rotary engine.
All those "little 1.3ltr". Rotary mazda engines were infact 2.6 litre equivalent capacity.

Re: This might be a great donor car model

Posted: Sep 29 2017 8:47pm
by spinningmagnets
If treated in accordance with the proper maintenance, the Wankel rotary can be reliable and long-lasting. That being said, it simply cannot take the abuse that a current piston engined design can. Rather than having a steel block and aluminum pistons, the rotary has a steel rotor and the running surface of the block is chrome-plated aluminum.

If the rotor tip-seals wear away into the chamber wall (regardless of the reason), as soon as the chrome plating fails in one spot, the block dies very rapidly after that. Once the block is damaged enough that the motor is blowing oil...you have to replace the block.

Either way, I have noticed that there is a regular stream of RX-7's for sale in very good shape with a "blue smoke" engine for sale )over the past decade), and none of them will pass a smog test until they have a full rebuild. I have actually seen V8-swapped RX's, but I personally would use a turbo V6...or an electric conversion. Making it an EV seems like it would be the easiest swap, because there are a lot of options when configuring the battery shape (likely in two blocks, one in front, one in the back seat).

Its still just 2WD, but...if you didn't want max range in the battery size, the performance would be phenomenal.

Re: This might be a great donor car model

Posted: Sep 29 2017 11:06pm
by Hillhater
Contrary to popular folk law, mazda rotary chambers(blocks) are readily refurbished.
There are even people who have devised their own equipment to grind the chambers and refsurface with various plasma sprayed materials.
The rotaries biggest issue is emmissions due to the open porting system.