Torque vs Horsepower

[natto fire]

Originally posted by: Smartazz
That's part of the reason why diesel engines on trucks last so long. The first reason is that they are overbuilt and the other is that they are consistently on lower rpms, I also think that this may be the reason why single engine planes have huge displacement for so little horsepower and they rev really low as a result.

Well, you still have to factor in mean piston speed. Although diesels rev low, they usually have crazy long strokes, which still makes for high piston speeds and therefore, engine wear. While rod to stroke ratio is certainly not the end all be all of engine reliability, it can be an indicator of how hard the main bearings/wrist pins are being thrashed about.

 

[Demon-Xanth]

Originally posted by: Captain Howdy

Originally posted by: Smartazz
That's part of the reason why diesel engines on trucks last so long. The first reason is that they are overbuilt and the other is that they are consistently on lower rpms, I also think that this may be the reason why single engine planes have huge displacement for so little horsepower and they rev really low as a result.

Well, you still have to factor in mean piston speed. Although diesels rev low, they usually have crazy long strokes, which still makes for high piston speeds and therefore, engine wear. While rod to stroke ratio is certainly not the end all be all of engine reliability, it can be an indicator of how hard the main bearings/wrist pins are being thrashed about.

Fun fact: a 5.9L Cummins ISB weighs in at 1050 LBs. That's right, an engine with the displacement of an LS2 weighs more than twice it's weight. The engine is built to be a million mile engine. But the oily nature of diesel fuel and the use of keystone rings also help. Diesels are so overbuilt because unlike car engines that will use the HP and then go back down, diesels are asked to use the HP for hours on end. If you're towing a trailer over the Sierra Nevadas, you're going to be going uphill with a heavy load for about three hours. That's not an easy thing for an engine. So durability becomes much more of an issue, imagine what a high revving four banger would be like if you held it at 8000RPM for three hours a day regularly. Go ahead, I'll get the broom. That's effectively what diesels are asked to do. And they're built to answer the call.

 

[Demon-Xanth]

As an example of a car with a torque curve that is high end:
http://www.turbo-kits.com/imag...x8_turbo_kits_dyno.jpg

A dyno of a turbo'ed RX8

 

[91TTZ]

Originally posted by: Demon-Xanth
As an example of a car with a torque curve that is high end:
http://www.turbo-kits.com/imag...x8_turbo_kits_dyno.jpg

A dyno of a turbo'ed RX8

Not bad.

 

[91TTZ]

Get an electric car. Then you can have max torque at 0 rpm.

 

[Zenmervolt]

Originally posted by: kevinthenerd

Originally posted by: Zenmervolt

Originally posted by: kevinthenerd
Nice dyno. I'd rather have that than a peaky motor that makes 400hp after spooling up.

Let's take 2 cars, otherwise identical, with only the powerband difference.

Car 1: 400 ft-lbs of torque from 1,000 RPM through redline (in this example, 5252 RPM to make the calculations simple)

Car 2: Low torque at 1,000 RPM, building slowly then suddenly spiking to 400 ft-lbs at redline (5252 RPM)

Which car is faster? Both engines' peak power is 400 HP at 5252 RPM. Car 2 has the "peaky" engine that you say you'd rather have.

That's all I've been saying. Ideally, you have a big, fat, wide torque curve. That will yield large amounts of HP too. Peak values are irrelevant really. What you want is maximum area under the HP curve.

ZV

???

We've proven that I cannot read...

ZV

 

[kevinthenerd]

Originally posted by: 91TTZ

Originally posted by: Demon-Xanth
As an example of a car with a torque curve that is high end:
http://www.turbo-kits.com/imag...x8_turbo_kits_dyno.jpg

A dyno of a turbo'ed RX8

Not bad.

Not bad? 326 is crap for that engine. First of all, they only dyno'ed it to around 7790 rpm. They probably chose too small of a turbo because people always misunderstand the air flow requirements of a Wankel. The stock motor delivers 247 hp @ 8500 rpm. Emissions hold back that engine from phenomenal performance. Out of the box, the engine runs very rich with whacked out maps to get the exhaust gases hot enough to burn the left-over hydrocarbons. With peripheral porting, 3mm apex seals, and a good tune, I wouldn't be surprised to get 500 hp out of that engine without a turbo.

My friend told me about a guy who ran a 6-rotor first-gen RX-7 in a naturally aspirated class dominated by expensive muscle car setups. He had half the money in his car as they did, and he was beating their 10s with 7s (ET).

 

[Demon-Xanth]

Originally posted by: kevinthenerd
Not bad? 326 is crap for that engine. First of all, they only dyno'ed it to around 7790 rpm. They probably chose too small of a turbo because people always misunderstand the air flow requirements of a Wankel. The stock motor delivers 247 hp @ 8500 rpm. Emissions hold back that engine from phenomenal performance. Out of the box, the engine runs very rich with whacked out maps to get the exhaust gases hot enough to burn the left-over hydrocarbons. With peripheral porting, 3mm apex seals, and a good tune, I wouldn't be surprised to get 500 hp out of that engine without a turbo.

My friend told me about a guy who ran a 6-rotor first-gen RX-7 in a naturally aspirated class dominated by expensive muscle car setups. He had half the money in his car as they did, and he was beating their 10s with 7s (ET).

Okay, I need to raise the BS flag here.

 

[deanx0r]

Horsepower for the track.
Torque for the street.

/thread.

 

[kevinthenerd]

Originally posted by: Demon-Xanth

Originally posted by: kevinthenerd
Not bad? 326 is crap for that engine. First of all, they only dyno'ed it to around 7790 rpm. They probably chose too small of a turbo because people always misunderstand the air flow requirements of a Wankel. The stock motor delivers 247 hp @ 8500 rpm. Emissions hold back that engine from phenomenal performance. Out of the box, the engine runs very rich with whacked out maps to get the exhaust gases hot enough to burn the left-over hydrocarbons. With peripheral porting, 3mm apex seals, and a good tune, I wouldn't be surprised to get 500 hp out of that engine without a turbo.

My friend told me about a guy who ran a 6-rotor first-gen RX-7 in a naturally aspirated class dominated by expensive muscle car setups. He had half the money in his car as they did, and he was beating their 10s with 7s (ET).

Okay, I need to raise the BS flag here.

You don't need an engine lift to work on a Wankel. They're extremely light. A stock two-rotor from a first-gen (which had a carburetor and was in a crappy state of tune) gave over 100hp, so 300hp from a six-rotor is the bare minimum starting point. In a Wankel you have all different porting options ranging from stock to race, including J porting, bridge porting, and peripheral porting. You can order custom race engines and whatnot from Pineapple Racing, and perhaps on their website, you can get an idea of what that engine can do before you raise the ignorant flag.

Don't forget about the Mazda 787B. It used basically a Cosmo engine (3-rotor) to develop so much horsepower that it was quickly banned.

 

[kevinthenerd]

...

 

[deanx0r]

Originally posted by: kevinthenerd
Don't forget about the Mazda 787B. It used basically a Cosmo engine (3-rotor) to develop so much horsepower that it was quickly banned.

The Mazda 787B engine was a quad-rotor.
And they were never banned from LeMans, they just failed to be competitive in the long run.

 

[91TTZ]

Originally posted by: kevinthenerd

Originally posted by: 91TTZ

Originally posted by: Demon-Xanth
As an example of a car with a torque curve that is high end:
http://www.turbo-kits.com/imag...x8_turbo_kits_dyno.jpg

A dyno of a turbo'ed RX8

Not bad.

Not bad? 326 is crap for that engine. First of all, they only dyno'ed it to around 7790 rpm. They probably chose too small of a turbo because people always misunderstand the air flow requirements of a Wankel. The stock motor delivers 247 hp @ 8500 rpm. Emissions hold back that engine from phenomenal performance. Out of the box, the engine runs very rich with whacked out maps to get the exhaust gases hot enough to burn the left-over hydrocarbons. With peripheral porting, 3mm apex seals, and a good tune, I wouldn't be surprised to get 500 hp out of that engine without a turbo.

My friend told me about a guy who ran a 6-rotor first-gen RX-7 in a naturally aspirated class dominated by expensive muscle car setups. He had half the money in his car as they did, and he was beating their 10s with 7s (ET).

It's not bad because it's a realistic street car, not a 6 rotor, 7 second beast. And making the mixture richer does not make the exhaust gases hotter, it makes them cooler.

 

[kevinthenerd]

Originally posted by: deanx0r

Originally posted by: kevinthenerd
Don't forget about the Mazda 787B. It used basically a Cosmo engine (3-rotor) to develop so much horsepower that it was quickly banned.

The Mazda 787B engine was a quad-rotor.
And they were never banned from LeMans, they just failed to be competitive in the long run.

I'm sorry. It was a doubled-up 13B. My mistake. The FIA banned Wankels at the 1991 season, though. A similar thing happened all around motorsport. It's hard to race a Wankel because nobody allows them. They're too fast and too light, and it's hard to compare Wankel displacement with piston-engine displacement while being fair. My least favorite example was the banning of the Wankel (typically seen as a 300 cc Sachs) from Formula SAE.

 

[91TTZ]

Originally posted by: kevinthenerd

You don't need an engine lift to work on a Wankel. They're extremely light. A stock two-rotor from a first-gen (which had a carburetor and was in a crappy state of tune) gave over 100hp, so 300hp from a six-rotor is the bare minimum starting point. In a Wankel you have all different porting options ranging from stock to race, including J porting, bridge porting, and peripheral porting. You can order custom race engines and whatnot from Pineapple Racing, and perhaps on their website, you can get an idea of what that engine can do before you raise the ignorant flag.

Don't forget about the Mazda 787B. It used basically a Cosmo engine (3-rotor) to develop so much horsepower that it was quickly banned.

The wankel is not that light. You still need an engine lift to work on it, unless you can curl 250-300 lbs while you unbolt it.

It's also a horribly inefficient engine. People that are amazed by them often don't just understand them. They are not as reliable as a piston engine and get worse gas mileage for the same power produced.

Most of the fools that argue with me about this believe that the rotors in those engines spin at 8,000+ rpms. They just don't understand how they work.

 

[91TTZ]

Originally posted by: kevinthenerd

Originally posted by: deanx0r

Originally posted by: kevinthenerd
Don't forget about the Mazda 787B. It used basically a Cosmo engine (3-rotor) to develop so much horsepower that it was quickly banned.

The Mazda 787B engine was a quad-rotor.
And they were never banned from LeMans, they just failed to be competitive in the long run.

I'm sorry. It was a doubled-up 13B. My mistake. The FIA banned Wankels at the 1991 season, though. A similar thing happened all around motorsport. It's hard to race a Wankel because nobody allows them. They're too fast and too light, and it's hard to compare Wankel displacement with piston-engine displacement while being fair.

It's the same deal with 4 stroke pistons engines vs. 2 stroke piston engines. You need to rate the displacement in a way which reflects the displacement of powerstrokes actually used.

 

[kevinthenerd]

Originally posted by: 91TTZ

Originally posted by: kevinthenerd

You don't need an engine lift to work on a Wankel. They're extremely light. A stock two-rotor from a first-gen (which had a carburetor and was in a crappy state of tune) gave over 100hp, so 300hp from a six-rotor is the bare minimum starting point. In a Wankel you have all different porting options ranging from stock to race, including J porting, bridge porting, and peripheral porting. You can order custom race engines and whatnot from Pineapple Racing, and perhaps on their website, you can get an idea of what that engine can do before you raise the ignorant flag.

Don't forget about the Mazda 787B. It used basically a Cosmo engine (3-rotor) to develop so much horsepower that it was quickly banned.

The wankel is not that light. You still need an engine lift to work on it, unless you can curl 250-300 lbs while you unbolt it.

It's also a horribly inefficient engine. People that are amazed by them often don't just understand them. They are not as reliable as a piston engine and get worse gas mileage for the same power produced.

Most of the fools that argue with me about this believe that the rotors in those engines spin at 8,000+ rpms. They just don't understand how they work.

Don't understand them? Here's the beginning of a simulation I'm writing to design my own (written for Quick BASIC):

DECLARE FUNCTION FTNX! (THETA!, BIGR!, LILR!, D!)
DECLARE FUNCTION FTNY! (THETA!, BIGR!, LILR!, D!)
CONST PI = 3.14159265358979#


N = 3


SELECT CASE N
CASE 2
FACTOR = .6
RANGE = 3
CASE 3
FACTOR = .5
RANGE = 2
CASE 4
FACTOR = .4
RANGE = 1.6
CASE 5
FACTOR = .4
RANGE = 1.4
CASE 6
FACTOR = .35
RANGE = 1.4
CASE 7
FACTOR = .3
RANGE = 1.4
CASE ELSE
FACTOR = .3
RANGE = 1.4
END SELECT




'CLS
ASPECT = 640 / 200
'7 320x200
'8 640x200
'9 640x350
ASPECT = ASPECT / 1.25 'Laptop
ASPECT = ASPECT / 1.25
ASPECT = ASPECT / 1.25






BIGR = 1
LILR = 1 / (N - 1)
'Higher values of D are more aggressive, i.e. more compression and wear
D = LILR * FACTOR


SCREEN 8, , 2, 0
PAINT (0, 0), 1
JUSTSTARTED = 1
STEPS = 300
WINDOW (-ASPECT * RANGE, -RANGE)-(ASPECT * RANGE, RANGE)
FOR THETA = 0 TO ((STEPS + 1) / STEPS) * 2 * PI STEP PI / STEPS
X = FTNX(THETA, BIGR, LILR, D)
Y = FTNY(THETA, BIGR, LILR, D)
IF JUSTSTARTED = 1 THEN
PSET (X, Y), 8
JUSTSTARTED = 0
ELSE
LINE -(X, Y), 8
END IF
NEXT THETA
PAINT (0, 0), 0, 8

PRINT "Rotary Animation"
PRINT "N = "; N
PRINT "BIGR = "; BIGR
PRINT "LILR = "; LILR
PRINT "D = "; D



SCREEN 8, , 1, 0

FOR K = 3 TO 0 STEP -.01





JUSTSTARTED = 1
TOTALX = 0
TOTALY = 0
FOR P = 0 TO N - 1
X = FTNX(((P / N) + K) * (2 * PI), BIGR, LILR, D)
Y = FTNY(((P / N) + K) * (2 * PI), BIGR, LILR, D)
TOTALX = TOTALX + (1 / N) * X
TOTALY = TOTALY + (1 / N) * Y
IF JUSTSTARTED = 1 THEN
PSET (X, Y)
FIRSTX = X
FIRSTY = Y
JUSTSTARTED = 0
ELSE
LINE -(X, Y)
END IF
NEXT P
LINE (X, Y)-(FIRSTX, FIRSTY)
IF TOTALX > MAXX THEN MAXX = TOTALX
IF TOTALX < MINX THEN MINX = TOTALX
IF TOTALY > MAXY THEN MAXY = TOTALY
IF TOTALY < MINY THEN MINY = TOTALY



'PAINT (TOTALX, TOTALY), 8, 15

'DUMMY$ = INPUT$(1)
PCOPY 1, 0
PCOPY 2, 1

NEXT K



'DUMMY$ = INPUT$(1)

FUNCTION FTNX (THETA, BIGR, LILR, D)
FTNX = (BIGR + LILR) * COS(THETA) - D * COS(THETA * ((BIGR + LILR) / LILR))
END FUNCTION

FUNCTION FTNY (THETA, BIGR, LILR, D)
FTNY = (BIGR + LILR) * SIN(THETA) - D * SIN(THETA * ((BIGR + LILR) / LILR))
END FUNCTION

Copyright Kevin Durette, 2007. All Rights Reserved.

 

[kevinthenerd]

Originally posted by: 91TTZ

Originally posted by: kevinthenerd

You don't need an engine lift to work on a Wankel. They're extremely light. A stock two-rotor from a first-gen (which had a carburetor and was in a crappy state of tune) gave over 100hp, so 300hp from a six-rotor is the bare minimum starting point. In a Wankel you have all different porting options ranging from stock to race, including J porting, bridge porting, and peripheral porting. You can order custom race engines and whatnot from Pineapple Racing, and perhaps on their website, you can get an idea of what that engine can do before you raise the ignorant flag.

Don't forget about the Mazda 787B. It used basically a Cosmo engine (3-rotor) to develop so much horsepower that it was quickly banned.

The wankel is not that light. You still need an engine lift to work on it, unless you can curl 250-300 lbs while you unbolt it.

It's also a horribly inefficient engine. People that are amazed by them often don't just understand them. They are not as reliable as a piston engine and get worse gas mileage for the same power produced.

Most of the fools that argue with me about this believe that the rotors in those engines spin at 8,000+ rpms. They just don't understand how they work.

I never said they were efficient, but the RX-8 in particular is a lot less efficient than it could be because of its fuel mapping. The compression ratio on that motor isn't spectacular either. People don't understand that the squished area that causes higher heat transfer (and less efficiency) can also help detonation resistance because of the way the flame front travels.

A lack of reliability can usually be linked to a lack of maintenance; people don't understand that Wankel engines are oiled like 2-strokes. Guys with old RX-7s typically just mix oil with their gas when the intake oil pump goes out. That intake oil pump is the most overlooked part that piston guys don't even know to check, and I think that ignorance is just part of the reason why Wankel engines don't do as well as they could. If everyone was running a Wankel engine, don't you think it'd be hard to find a local mechanic who understood everything about connecting rods and valve trains?

The acceleration of the rotor within the Wankel engine is constant, which is a big advantage over a piston engine. A piston engine is at the mercy of the rod-to-stroke ratio to determine the maximum acceleration, and even then the best you'll ever get is a sinusoidal piston path with inflection points (which is wasted time when you could be applying a correcting force). The constant inward acceleration of a Wankel rotor is only based on orbital speed and the radius of that path, which is governed by rotor size and epitrochoid eccentricity.

I never said that the Wankel was the ultimate solution for an econobox, but it's hard to beat it as a sports car or race car engine.

 

[kevinthenerd]

Originally posted by: 91TTZ

Originally posted by: kevinthenerd

Originally posted by: deanx0r

Originally posted by: kevinthenerd
Don't forget about the Mazda 787B. It used basically a Cosmo engine (3-rotor) to develop so much horsepower that it was quickly banned.

The Mazda 787B engine was a quad-rotor.
And they were never banned from LeMans, they just failed to be competitive in the long run.

I'm sorry. It was a doubled-up 13B. My mistake. The FIA banned Wankels at the 1991 season, though. A similar thing happened all around motorsport. It's hard to race a Wankel because nobody allows them. They're too fast and too light, and it's hard to compare Wankel displacement with piston-engine displacement while being fair.

It's the same deal with 4 stroke pistons engines vs. 2 stroke piston engines. You need to rate the displacement in a way which reflects the displacement of powerstrokes actually used.

But, like the Wankel, you have more than just displacement affecting your power. In the case of Wankel vs. 4-stroke piston, you have to deal with power to weight, accelerations for a given air flow, etc.

In the case of 4-stroke vs 2-stroke, you have to take into consideration that the 2-stroke has to take away more heat. You need to control the fuel/oil mixture as well as the fuel/air mixture. The 2-stroke has a harder time breathing and especially scavenging. The 4-stroke has a lot more control over valve timing events, and in a modern engine you can even have variable valve timing. The ram-charging effect in a 4-stroke is more significant (despite the crankcase of the 2-stroke) because of the ability to hold the intake valve open without sacrificing exhaust extraction. All of these factors wind up making a fair rules balance between the two difficult, and with the lack of literature and widespread experiences with the Wankel and the radically different gas exchange processes, the question only becomes hazier.

 

[Zenmervolt]

Originally posted by: kevinthenerd
I never said that the Wankel was the ultimate solution for an econobox, but it's hard to beat it as a sports car or race car engine.

As long as you don't care about fuel efficiency at all, they're great, yes. Unfortunately, when you have to stop twice during a race where everyone else only has to stop once, it's really, really hard to win.

They're interesting engines to be sure, but there's just something wrong to me about any engine that intentionally burns oil. (The advantage for things like chainsaws is that being two-cycle allows the engine to remain lubricated regardless of orientation without needing some sort of quasi-miracle oil sump setup.) The Wankel burns more fuel to make the same power and it produces greater amounts of emissions. From an engineering standpoint it's a cool toy, from an efficiency standpoint it's a false-start.

ZV

 

[kevinthenerd]

Originally posted by: Zenmervolt

Originally posted by: kevinthenerd
I never said that the Wankel was the ultimate solution for an econobox, but it's hard to beat it as a sports car or race car engine.

As long as you don't care about fuel efficiency at all, they're great, yes. Unfortunately, when you have to stop twice during a race where everyone else only has to stop once, it's really, really hard to win.

They're interesting engines to be sure, but there's just something wrong to me about any engine that intentionally burns oil. (The advantage for things like chainsaws is that being two-cycle allows the engine to remain lubricated regardless of orientation without needing some sort of quasi-miracle oil sump setup.) The Wankel burns more fuel to make the same power and it produces greater amounts of emissions. From an engineering standpoint it's a cool toy, from an efficiency standpoint it's a false-start.

ZV

In mass production, I believe the Wankel could be a cheap alternative for small engines like those. Despite the poor emissions, I think you'd still outdo the emissions of a 2-stroke, but that's honestly just speculation. Fitting plugs into the tiny chambers could be a problem without expensive custom plugs. (A Wankel relies heavily on kernel formation from multiple plugs because the flame front travels too slowly in its pancake combustion chamber.)

 

[91TTZ]

Originally posted by: kevinthenerd


Don't understand them? Here's the beginning of a simulation I'm writing to design my own (written for Quick BASIC):

Nice work.

 

[Zenmervolt]

Originally posted by: kevinthenerd

Originally posted by: Zenmervolt

Originally posted by: kevinthenerd
I never said that the Wankel was the ultimate solution for an econobox, but it's hard to beat it as a sports car or race car engine.

As long as you don't care about fuel efficiency at all, they're great, yes. Unfortunately, when you have to stop twice during a race where everyone else only has to stop once, it's really, really hard to win.

They're interesting engines to be sure, but there's just something wrong to me about any engine that intentionally burns oil. (The advantage for things like chainsaws is that being two-cycle allows the engine to remain lubricated regardless of orientation without needing some sort of quasi-miracle oil sump setup.) The Wankel burns more fuel to make the same power and it produces greater amounts of emissions. From an engineering standpoint it's a cool toy, from an efficiency standpoint it's a false-start.

ZV

In mass production, I believe the Wankel could be a cheap alternative for small engines like those. Despite the poor emissions, I think you'd still outdo the emissions of a 2-stroke, but that's honestly just speculation. Fitting plugs into the tiny chambers could be a problem without expensive custom plugs. (A Wankel relies heavily on kernel formation from multiple plugs because the flame front travels too slowly in its pancake combustion chamber.)

I dunno, you'd still need a sump of some sort, unlike a 2-cycle. Unless you built some sort of 2-cycle Wankel, in which case you're back to square 1 on the emissions.

ZV

 

[Apex]

Originally posted by: kevinthenerd

Originally posted by: 91TTZ

Originally posted by: kevinthenerd

Originally posted by: deanx0r

Originally posted by: kevinthenerd
Don't forget about the Mazda 787B. It used basically a Cosmo engine (3-rotor) to develop so much horsepower that it was quickly banned.

The Mazda 787B engine was a quad-rotor.
And they were never banned from LeMans, they just failed to be competitive in the long run.

I'm sorry. It was a doubled-up 13B. My mistake. The FIA banned Wankels at the 1991 season, though. A similar thing happened all around motorsport. It's hard to race a Wankel because nobody allows them. They're too fast and too light, and it's hard to compare Wankel displacement with piston-engine displacement while being fair.

It's the same deal with 4 stroke pistons engines vs. 2 stroke piston engines. You need to rate the displacement in a way which reflects the displacement of powerstrokes actually used.

But, like the Wankel, you have more than just displacement affecting your power. In the case of Wankel vs. 4-stroke piston, you have to deal with power to weight, accelerations for a given air flow, etc.

In the case of 4-stroke vs 2-stroke, you have to take into consideration that the 2-stroke has to take away more heat. You need to control the fuel/oil mixture as well as the fuel/air mixture. The 2-stroke has a harder time breathing and especially scavenging. The 4-stroke has a lot more control over valve timing events, and in a modern engine you can even have variable valve timing. The ram-charging effect in a 4-stroke is more significant (despite the crankcase of the 2-stroke) because of the ability to hold the intake valve open without sacrificing exhaust extraction. All of these factors wind up making a fair rules balance between the two difficult, and with the lack of literature and widespread experiences with the Wankel and the radically different gas exchange processes, the question only becomes hazier.

Isn't a fully dressed 13B-REW 327 lbs?

That's light, but not incredibly so.

I think the real advantage is it's reasonably light AND compact. It's the combo of those two things which makes it a reasonably nice engine.

 

[Demon-Xanth]

Mazda 12A rotary 348 (RX7) (with oil and water)
Mazda 12A rotary 356 (Japanese model turbo, EFI)
Mazda 13A rotary 301 (R130 Lucia - Japan only) (bare)
Mazda 13B race 242 2-rotor race motor, with accessories

Still not feather weights. Compare to:
Porsche 911/6 280
Buick/Rover 215 V8 318 (and Olds)
Honda B18B four 326 1995 Civic
Lotus 907 (Esprit) 275
Subaru 2.2L 269
Suzuki Cultus 3 cyl 139 (sorry, just had to throw in the Geo Metro's engine )
VW flat-4 air cooled 200