Great article on the 4rotor Corvette
#1
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Great article on the 4rotor Corvette
One of my Corvette friends sent me this article.
http://www.telegraph.co.uk/motoring/.../mfvette30.xml
http://www.telegraph.co.uk/motoring/.../mfvette30.xml
#4
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.
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#5
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Originally Posted by Sapphonica
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. ![Nono](https://www.rx8club.com/images/smilies/nono.gif)
![Nono](https://www.rx8club.com/images/smilies/nono.gif)
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.
#8
Originally Posted by brillo
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.
#9
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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.
#10
Originally Posted by brillo
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?
Last edited by Shoafb; 10-11-2006 at 07:25 AM.
#11
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Originally Posted by Michael
Man, with that fwd auto tranny and 4 cyl cavy engine, that beast must have run 10's.
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Originally Posted by Shoafb
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?
Maybe Mazda can bring the 8 track back in the next Rx?
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Originally Posted by alnielsen
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.
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Originally Posted by brillo
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.
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."
#16
Originally Posted by r0tor
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."
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.
#17
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Originally Posted by Sapphonica
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. ![Nono](https://www.rx8club.com/images/smilies/nono.gif)
![Nono](https://www.rx8club.com/images/smilies/nono.gif)
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!!!
Last edited by rotarygod; 10-17-2006 at 03:14 AM.
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Originally Posted by rotarygod
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!!!
Why not compare that engine to the first 12A and 13B engines of that time?
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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.
Last edited by r0tor; 10-17-2006 at 06:39 AM.
#19
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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.
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.
Last edited by rotarygod; 10-17-2006 at 10:57 AM.
#21
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Originally Posted by rotarygod
There are many other engines today that make far more power per liter of displacement. Some things never change.
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....
#22
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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.
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.
Last edited by rotarygod; 10-17-2006 at 11:50 AM.
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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.............
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.............
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#25
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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
combinations Mazda has under wraps in it's R&D department