One of my Corvette friends sent me this article.

http://www.telegraph.co.uk/motoring/.../mfvette30.xml

 

That is awesome. I am glad the guy saved the car and shocked that they can be so embarrassed about the car.

 

Man, with that fwd auto tranny and 4 cyl cavy engine, that beast must have run 10's.

 

I find it quite interesting that GM made a 4 liter 2 rotor engine. I've read many times on this list about the technical problems of making the displacement bigger. Since GM was able to do it in the 70s, some of the arguments against large-displacement rotaries must be specious.

 

The reason it never went into mass production was the fact they couldn't get larger displacement rotary's to work efficiently. a 4 liter 2 rotor is technically feasible, but the efficiency would be terrible due to thermal issues, and flame front travel.

 

Wow I knew GM saw the rotary as non feasible, but to be so embarrassed about the car and the engine?

 

Interesting read.

 

...just like the Renesis, which gets worse gas mileage than a C6 Vette, makes a small fraction of the power, AND turns a lot of the chemical energy in the gasoline into thermal energy instead of mechanical energy to make the drivetrain go roundy-roundy.

 

if you think that the renesis is inefficient, I should show you the brake specific fuel consumption data of the older larger displacement engines, I have the data in SAE papers somewhere. In fairness they were older tests and not direct injection.

 

So the Renesis is about as efficient as a 25+ year old piston design?

Maybe Mazda can bring the 8 track back in the next Rx?

 

Many of the older kit cars used the Oldsmobile Toronado FWD transaxle. They just put it in the rear of the car instead of the front and created a mid-engine car. I specifically remember a Ford Pantera and GT40 replicas using this. It was the best way to handle large horsepower engines with out using expencive racing transmissions.

 

I sense


coming...

 

The DeTomaso Pantera used a ZF transaxle.

 

I did say replicas.

 

efficiency? Who cares when they had a massive 4 rotor making 420hp back in the early 70's... and that was with a poor seal system that they never did figure out (which ultimately caused the engines demise in GM)


http://www.illustratedcorvetteseries...3_4-Rotor.html
"On a one-mile check track, GM president Ed Cole and Duntov clicked off 148 mph in the 4-rotor Corvette. The car started out with a throaty roar and hit top speed, belching flames and making an ear piercing scream. It was actually faster than a '73 454 Corvette! But not even powerful friends in high places could get this prototype into production."

 

The current 06 vette is close to the EPA of the current Renesis with about 2x the hp and tq. Compare current Piston engines to current Rotary engines if you want to be fair.

 

Mazda tried it several times. If it's so feasible, why haven't we seen one in production? Instead of a larger 2 rotor such as the prototype 15A and 21A engines, they made 3 and 4 rotors based off of the 13B sized rotors for racing. Why not larger rotors? A 2 rotor 21A should have easily been the equivalent of a 20B 3 rotor. So what that the 21A only made 180 hp. If they were so great, why didn't anyone else ever build one and get it farther than prototypes? Maybe if they had stuck to smaller engines like Mazda had, they wouldn't have given up in the face of the gas crisis back then. Everything is about compromise. There is a balance to everything. Just like porting or turbos, making it larger isn't always the correct answer and many times is the wrong one.

If GM had a 585 cu. in. 4 rotor engine making 420 hp, that's only 210 hp per 2 rotors (292.5 cu. in.). It was a peripheral port engine over 3 times larger per rotor than the current rotary. That's downright pathetic! We can beat that amount of power per rotor with smaller rotors and side ports!!!

 

Yea, we can (bearly) beat 210hp per 2 rotors 30 years later with the help of fuel injection, modern intake design, and advanced ecu work.

Why not compare that engine to the first 12A and 13B engines of that time? .

Another comparison that could be made is the Mercedes 4 rotor in the late 60's that had direct injection and .6L per rotor - that could only muster 350hp though. Impressive for its displacement compared to GM's, but still not as powerful. They also had a 280hp 3 rotor with direct injection and dual spark ignition - but only had 280hp.



The only thing that stopped GM was they never figured out how to make the apex seal that would last like Mazda did.

 

I'll do better than that. I'll go back to 1967, 5 years ealier than the GM engine. The Cosmo 110S (L10A) for '67 had a side intake port 10A engine that made 110 hp. In '68 the Cosmo (L10B) made 130 hp. That was from a 1 liter! Mercedes and GM were pathetic by comparison for what the engines were and they were using periperal intake ports! It's no wonder that only Mazda continued on with the rotary.

While a current 13B peripheral port engine can top 350 hp, even back then the 12A P-port engines could hit 240 hp. If it had 4 rotors it could have had 480 hp back then and that's from a 2.4 liter. The GM engine was nothing special no matter how you look at it or what you compare it to from any time period. Our current side port engines don't just barely top 200. They beat it with authority. The only thing intriguing about the GM engine was it's displacement. In traditional American engine fashion, large but not very powerful for it's size. Even today's GM LS series engine with all of it's might and authority isn't very impressive when we talk about horsepower per liter. Their rotary was no different. There are many other engines today that make far more power per liter of displacement. Some things never change.

 

the LS2 in the vette gets 400hp at 18/28mpg is hp per liter really worth bragging about?

 

It all goes back to the age long argument...

on the track would you rather have a 400 hp 6L engine putting out a paltry 66 hp/L or a 240 hp 2L engine putting out 120 hp/L....

 

How many of us drive on a race track all day? I swear that sounds like a 7 forum argument. They all want race cars and gladly give up creature comforts and powerband but never drive on a track. The street is all that matters. The Vette wasn't built as a race car. It's a street car. Would you really want a large rotary on the street that gets even worse mileage can can't pass emissions? In case you haven't noticed, there are many people that run smaller engines at the track.

There are 2 things that are important here. The first is that the GM rotary wasn't even a technological marvel for it's time. The second is that a larger rotor isn't necessarily better. It isn't. I for one think we need smaller rotors but just more of them. Larger rotors are a bad idea in every way shape and form.

 

no... the arguement is usually a V8 owner vs a civic owner...

goes something like...
ricer-> "Pfft my car has 100 hp/l... If my car was a 6L engine I'd have 600 hp instead of your 400hp"
V8 guy-> "Lets see how badly my low tech 400hp V8 whoops your 200 hp ***"

 

Its just amazing to think this things actually exists & the lies about it burning in 1977 do show the GM embarrassment. Not to mention the meting with the GM execs this guy had.

Personally, he should fit the GMRE engine for authenticity & the fact thata working example is still around is really amazing.

Long live this Corvette & its rotary power.............

 

This is a good thread. I'd love to see smaller rotors...but 3 of them. I'd love to see what kind of
combinations Mazda has under wraps in it's R&D department