Inefficient engines

  • Thread starter TopHat
  • 125 comments
  • 8,265 views
Toronado
The current small block is only a ten year old design. All of the other versions of the small-block built before 1996 are irrelavent to the conversation. Just putting it out there before that blows up into a full scale argument.
Click to expand...

OHV is only ten years old? That's news to me. I must have been driving flatheads in 1985. Probably explains the hairstyles.
 
I drive around with an "inefficient" european V6 with "only" 65.8bhp/litre, (194bhp/2946cc,) but I don't see it as being inefficient.

It does everything it needs to do. It does everything it is asked to do. It does everything that Peugeot/Citroen & Renault wanted it to do.

Yes, a 3 litre V6 is more than capable of supplying more power, but why does it need to? It is a relatively large engine in Europe (well above the average engine size) but it is not used in a "sports" car. With those kind of figures, the engine should be completely unstressed and should, theoretically, last a very long time.

The Clio V6 has the same basic engine, but with 250bhp which gives it 85bhp/litre. Is this engine more efficient than the one I have? The Clio V6 has a service interval of 12,000 miles. The "normal" V6 used in the 406/407/607/C5/Laguna/Safrane/Avantime etc has a service interval of 20,000 miles. Is the Clio engine still more efficient? Yes, the Clio V6 has more power, but it also needs more looking after.

Going by the bhp per litre formula, a wankel rotary is a very efficient engine, but RX7s need a new engine every 80,000 miles. That does not strike me as being very "efficient".
 
You guys are forgetting about "rotating mass" and some other things. AKA, Parasitic Loss. You're comparing HP per liter from V8s, V6's, and I4's. Because of less parasitic loss on a 4 banger, yes it's going to be "more efficient", but it's making no more that 200HP in a normal street car. As you move up to a V6 there's more parasitic loss and a little more inefficiencies. Now you increase the displacement more and add two cylinders and you have even more parasitic loss. Which is why you can't really say that American cars are the worst. It's not that, it's that they chose to make way more larger displacement engines. It's not something that is put into the design, it's just a fact that there's going to be more parasitic loss with a larger displacement engine.
 
^ Yet another good point that many of us overlooked.

(You will recieve a parting gift in the form of Kudos. Do what you wish with them.)
 
Poverty
But arguably someone would have a hell of alot easier time making a replica LS7 than a replica S85.

A serious question here thats been bugging me lately. Why do some manufacturers make such advanced engines when a simple one can do the job just as well or better? Anyone got any ideas ont his?
Click to expand...
Because it impresses lots of people like you.

You utterly failed to indicate what the advantage of the S85's complexity was in answer to my last post. The LS7 is simpler, cheaper, lighter, and more effective. Yet you are not impressed at all by its overall efficency (not its specific output, its overall efficiency for providing cost-effective, reliable, lightweight power). However, you are thoroughly impressed by the BMW engine based solely on its technology.
 
Out of all the engines, I would guess that the S2000 I-4 is the most efficient with at least 100 hp per liter, but the red line is sky-high, which may contribute to that factor.

@ Daan: That sounds like a perfectly fine engine to me, don't know why you thought it was inefficient.
--------------------------------------------------------------------------

Here are good engine outlines- 1-1.6 L i-4 - 100- 110 hp (Hyundai Accent 110 bhp 1.6 L)
1.6-2.4 I-4 110-170 (naturally aspirated) or 300 hp (turbo)-(Mazda3 2.0 L 150 hp 👍)


2.5-3.5 L V-6 OR I-6 180-280 hp - (Ford Fusion 3.0 L V-6 220 hp)

4.0-6.1 L V-8 250-450 hp- ( Dodge Charger 5.7 L V-8 350 hp :))

6.5L-8.5L V-8 V-10 V-12 430 hp and UP- ( Chevrolet Corvette 7.0 L V-8 505 hp )

Most of these engines IMO are good. Only wish GM would back off the push-rod engines.

EDIT: Honda S2000 at 116.5 hp per 1.1 L :drool:
 
MatttheTuner
Only wish GM would back off the push-rod engines.
Click to expand...
All of you guys keep saying this - insisting on it, in fact - yet none of you can come up with a valid reason about why pushrod engines are bad other than because it's basically an old design. So far no one has said anything more convincing than that.

RWD cars are an old design. Should we abandon them, too? We'll be in trouble, because FWD and AWD cars are old too. What are our options, if age of the fundamental design invalidates it?
 
Duke
All of you guys keep saying this - insisting on it, in fact - yet none of you can come up with a valid reason about why pushrod engines are bad other than because it's basically an old design. So far no one has said anything more convincing than that.

RWD cars are an old design. Should we abandon them, too? We'll be in trouble, because FWD and AWD cars are old too. What are our options, if age of the fundamental design invalidates it?
Click to expand...

I love the argument that "OHV is old" when OHC engines were invented and used before OHV's. Therefore, by their own logic, OHC engines should be phased out... Antiquated pieces of crap. :rolleyes:
 
Duke
All of you guys keep saying this - insisting on it, in fact - yet none of you can come up with a valid reason about why pushrod engines are bad other than because it's basically an old design. So far no one has said anything more convincing than that.

RWD cars are an old design. Should we abandon them, too? We'll be in trouble, because FWD and AWD cars are old too. What are our options, if age of the fundamental design invalidates it?
Click to expand...

OK playing devils advocate I will step in.

Pushrod engines (like most things in life) have pros and cons, the principal con of the pushrod design is the pushrods themselves can limit engine speed (as in rpms) due to a tendency for the rods themselves to flex at higher speeds (and a small risk of failure). The greater reciprocating mass also increases the parasitic losses within the engine. Even with this well designed push road engines are capable of 8,000rpm redlines, which is hardly shoddy.

However on a con side the pushrod design does reduce overall engine size and lower the centre of gravity (significantly in comparison to DOHC engines), this is a significant benefit for a race engine, in addition the more straightforward design does provide a very reliable engine.

However I don't consider the pushrod design to be bad because of this as OHC designs have pros and cons of their own.

Regards

Scaff
 
Scaff
Pushrod engines (like most things in life) have pros and cons, the principal con of the pushrod design is the pushrods themselves can limit engine speed (as in rpms) due to a tendency for the rods themselves to flex at higher speeds (and a small risk of failure). The greater reciprocating mass also increases the parasitic losses within the engine. Even with this well designed push road engines are capable of 8,000rpm redlines, which is hardly shoddy.
Click to expand...

You are correct that pushrod flex does occur in OHV enignes, although that is usually not a symptom of high rpms but of too much valve spring force. The high rpm evil is valve float, which leads to higher spring pressures, which leads to bending pushrods. But if you upgrade the springs, there is a upgraded pushrod in production to go along with them. And a NASCAR engine manages 9500 rpm for 500 miles at a time, so they are very capable of revving.

Also I was under the impression that the OHC engine will have more valavetrain inertia (at least a vee engine) because there are two camshafts rather than one, and also the timing chain is longer. The OHC engine design I know well (Ford Modular engines) have lifters and rockers just like a pushrod engine, so that inertia is there either way (unless Ford just have an oddball OHC design).

(I understand you're just trying to play devils advocate, I'm just debating the facts...in general I share your point-of-view)
 
skip0110
You are correct that pushrod flex does occur in OHV enignes, although that is usually not a symptom of high rpms but of too much valve spring force. The high rpm evil is valve float, which leads to higher spring pressures, which leads to bending pushrods. But if you upgrade the springs, there is a upgraded pushrod in production to go along with them. And a NASCAR engine manages 9500 rpm for 500 miles at a time, so they are very capable of revving.

Also I was under the impression that the OHC engine will have more valavetrain inertia (at least a vee engine) because there are two camshafts rather than one, and also the timing chain is longer. The OHC engine design I know well (Ford Modular engines) have lifters and rockers just like a pushrod engine, so that inertia is there either way (unless Ford just have an oddball OHC design).

(I understand you're just trying to play devils advocate, I'm just debating the facts...in general I share your point-of-view)
Click to expand...


My bad I forgot to mention the valve float (post in haste - look stupid at leisure), and while the NASCAR engine example is quite correct it is of course about the upper limit, a OHC fanboy could counter with an F1 engine reving to 20,000rpm.

The valve train inertia issue is one that personally I think is very difficult to judge as it depends massively (in my opinion) on the individual engine and a poorly designed engine of either type will suffer in the same way that a well designed engine of either type can reduce the issue.

One I did forget is that its generally a lot harder to utilise multi valve set-ups (as in more than two per cylinder) in pushrod designs, however one could again argue the pros and cons of multi value set-ups. Also remembering that while its harder to do with pushrods its not impossible.

For me both types of engines have a place and both exibit pros and cons, the world would be a poorer place with out the low down grunt of an American pushrod V8 or a highreving European V8, any true petrolhead is going to love them both.

👍

Scaff
 
Another thing to point out. In those so called "more efficent" engines with OHC's and small displacements. They make most of their power way up in the rpms. Some of the more well known big HP/liter cars are praised for this. But, they make that power at crazy RPMS!! Who really drives around at those engine speeds?? If you really want to talk about usable output I would think that one of these engines might even be less efficient at normal driving speeds, not to mention at peak power. Not as far as MPG but as far as HP/Liter. I'd rather make 300hp@6000rpm and 295ft lbs @4000 rpm in my caddy than 240hp@8900rpm 153 ft/lbs@ 7500 rpm in the s2000. We'll see which engine lasts the longest and gets the best gas milage at peak power?
 
speedy_2
Another thing to point out. In those so called "more efficent" engines with OHC's and small displacements. They make most of their power way up in the rpms. Some of the more well known big HP/liter cars are praised for this. But, they make that power at crazy RPMS!! Who really drives around at those engine speeds?? If you really want to talk about usable output I would think that one of these engines might even be less efficient at normal driving speeds, not to mention at peak power. Not as far as MPG but as far as HP/Liter. I'd rather make 300hp@6000rpm and 295ft lbs @4000 rpm in my caddy than 240hp@8900rpm 153 ft/lbs@ 7500 rpm in the s2000. We'll see which engine lasts the longest and gets the best gas milage at peak power?
Click to expand...

I already proved in my first post that these "more efficient" engines can and sometimes do make not only more power than the larger, "less efficient" engines, but also more peak torque at a lower RPM. That doesn't say much about the torque curve overall, but the point remains that very few roadcar engines are like the S2000's, no matter how laughable its powerband is. :lol:
 
neanderthal
gil. good points but comparing the half ton titan and tundra to 3/4 ton fords and chevys?????? really!!!! not quite apples to apples is it.
Click to expand...
Thank you.
But that is exactly my point.
You'll note that I said the equivalent trucks are about on par with each other. (okay, so maybe in a bit of a backhanded way).:sly:
But if half-ton pick-ups are the "apples" in this case, Toyota and Nissan aren't growning "oranges" (3/4 ton) yet.
And isn't it great how Ford, Chevy, and Dodge 3/4 ton diesel trucks are pulling down better fuel economy than any other manufacturer's half ton trucks?
My point is that Hp/Liter isn't the be all and end all of what determines a "good" engine.
The starter of this little debate was comparing OHV engines to DOHC/SOHC engines.
Is America behind in developing OHC engines? Who knows? Points can be made to prove that we've done it and didn't like it.
Back when I was a kid, if you had the know-how, you could turn Ford's SOHC 2.3 into a fire-breathing little monster with out even touching the bottom end of the engine.
GM's Quad four proved to be a powerful little "hand grenade."
That 2.3 is still around, but it's the least popular engine in the Ranger line-up. Why? because the v-6's have more "grunt" where it's useful.
If you go back to the '60's Ford did have a SOHC V-8, and it proved to be extremely powerful. It also need frequent adjustment to keep it running right.
But if you look at the way most of us drive in the US, you'll see that a slow turning, smooth quiet OHV engine suits us just fine. We spend a lot of time cruising vs accelerating. The 6.0 L in the Corvette, is about the pinnacle of OHV design. If it was a DOHC, the car that is already very fast, would still be very fast, and it would be more prone to breakage and high repair costs.
The OHV lends itself to "indifferent" maintenance, and continues to run well.
But OHC designs thrive on high revs. And that just isn't the way the majority of us like to drive.
Yeah, we get a big kick out of tromping on the gas. But in the grand scheme of things we like our power in the lower RPM band, and we use it in the lower RPM band.
 
Why GM didn't stick with OHC designs? Look no further than the LT5 from the Corvette ZR1. Sure, it make plenty of power, but it was fairly unreliable, and the costs of repairing them were quite high compared to the LT1 of the same era. Of course, the LT5's 405 BHP was quite impressive by the end of it's run in 1995, a number that wouldn't be seen again untill the C5 Z06 in late 2001 and early 2002 after the "Z06 2.0" was released.

It isn't that American automakers can't do it, we've done it, and it didn't work out to well. Keep in mind of course that the OHC heads on the LT5 were indeed designed by Lotus, so it isn't even worth debating that GM screwed them up...
 
Not to mention that it was very damned heavy, and barely any Chevy dealer in the country knows how to service the bloody things.
 
I'm happy they dropped it. I mean, sure, it will always hold a special place in many Corvette fan's hearts, but even then once the LS6 and LS7 hit the street, the LT5 has been for the most part been forgotten.
 
on the contrary i believe that the ZR1 will never lose its place in history because prior to it a vette was pretty much a straight line machine in comparison to porsches and ferraris and other euros. the ZR1 showed GM the vette could hang with the best of them. i believe its why the C5 was such a giant step in comparison to previous vettes.
 
Wolfe2x7
Due to the fact that engines with a low specific output tend to be more fuel efficient and cost less, I always keep the context of the vehicle that carries them in mind. However, that still doesn't eliminate glaring differences between manufacturers, specifically those from Detroit and those from Japan/Europe...

For example, the 1996 Toyota Corolla DX made 105hp from a 1.8L four-cylinder, which is about 58hp/L. Not amazing, but not bad considering the fact that it's supposed to be a fuel-efficient little compact car.
Meanwhile, the 1996 Ford Mustang GT made 215hp from a 4.6L V8, which is about 47hp/L......uh, what?
It's not like the GT produced a million times as much torque, either -- although it made 285lb.ft, which is 62lb.ft/L, at 3500rpm, the Corolla made 110lb.ft (61lb.ft/L), albeit at a significantly higher 4400rpm.

Nowadays, Ford have improved upon that same 4.6L to achieve a whopping 300hp, for 65hp/L, and 320lb.ft, for 70lb.ft/L, at 4500rpm.
What about Toyota? The Yaris makes 105hp from a 1.5L, which is 70hp/L, and 103lb.ft, which is 68lb.ft/L, at 4200rpm.

How is it that the small Toyotas are powered by engines that are about as power-efficient as Ford's musclecar icon? Surely, the Mustang should have been designed with a little more...performance in mind than the Yaris or Corolla, right?

Now, now, I'm sure some of you are crying foul because the Yaris' engine is bound to be of a newer design than the Mustang's modular engine, so let's take a look at one of the best and latest engines Detroit has offered, the LS7:

The Corvette Z06 makes 507hp from a 7L V8, which is 72hp/L. It also makes 470lb.ft, which is 67lb.ft/L, at 4800rpm.
Now, let's compare that to the BMW M5, which makes 80hp/L, and 71lb.ft/L with a torque peak of 4500rpm.....

Now, you may have noticed that I chose a more performance-oriented rival for the american car, and that would be a fair claim. It isn't quite as easy to find "civilian" cars that match the Z06's specific output as it is to find matches for the Mustang GT. However, there is one notable thing about my selection of the M5 (and I'm not referring to my BMW fanboyism)...the M5 I chose to go head-to-head with the 'Vette was the 1985 model, which made 282hp and 251lb.ft from a 3.5L 6-cylinder.

Furthermore, it isn't impossible to find an "ordinary" car to compare to Chevrolet's bang-for-your-buck masterpiece. One such car is the Nissan's Sentra, which makes 115hp from a 1.6L 4-cylinder, which is 72hp/L, and 110lb.ft, aka 69lb.ft/L, at 4500rpm.

Oh, and that's the 1995 Sentra.

Seriously, Detroit just doesn't know how to get good power out of an engine, and it isn't because they're "concentrating on torque." That's why I included the torque and peak torque RPM numbers in all of this. It's really rather depressing. :rolleyes:
Click to expand...

Now compare foreign engines of the same size, to American engines.
What about Toyota? The Yaris makes 105hp from a 1.5L, which is 70hp/L, and 103lb.ft, which is 68lb.ft/L, at 4200rpm.
Click to expand...
1996 Toyota Corolla DX made 105hp from a 1.8L four-cylinder, which is about 58hp/L.
Click to expand...
1990 Pontiac Grand Am - 180HP 2.3L, 160ft-lb, 30mpg.
1996 Pontiac Grand Am - 150HP 2.4L, 150ft-lb, 30mpg
The latter of which was the base engine for the car.
Also, in 1996, these are the same numbers you'll get for a Cavalier, and a Sunfire.
And from 90-95, you could find that 2.3L engine in Oldsmobile Calais, Chevy Beretta's, and a few others.

You wanna compare effeciency? Show the whole picture, rather than taking a huge engine against a small one.

I won't name the Ecotec, since I recently took a girls '06 Cobalt LS for a drive, and was VERY dissapointed to find the even with it's quoted 150hp, my Grand Am of '98, with the same power and weight, would simply slaughter it. Even moreso in low-mid rpm's.
 
neanderthal
on the contrary i believe that the ZR1 will never lose its place in history because prior to it a vette was pretty much a straight line machine in comparison to porsches and ferraris and other euros. the ZR1 showed GM the vette could hang with the best of them. i believe its why the C5 was such a giant step in comparison to previous vettes.
Click to expand...
What are you talking about? The main problem GM had with the C4 'Vette ws that it handled too well. GM designed it with handling in mind and made it a horrible car to live with because of it. With the added weight of the ZR-1 and the spongier suspension, it's a wonder that the ZR-1 handled well at all. Not to mention the fact that the C4 only needed more power to hang with the best of them.
 
But Wolf,
If the Toyota Corolla is more "efficient" than the Corvette,
How come the Corvette gets from 0-60 in 4.6 to 5.1 Seconds, and the Corolla S needs nearly 8 seconds?

A loaded question to be sure. The Vette has so many more liters of displacement. But that does prove out the arguement that there is no replacement for displacement.

"Effeciency" is one thing. But the only numbers that mean anything are on the stopwatch.

It doesn't always matter which car has the handling numbers on the skid-pad either. As obvious as it sounds the car with the lowest time is the most "efficient" for what ever test it was at that time.

The Toyota MR2 is one of the most sought after GT cars of its time. Yet it was powered by the relatively mild 2.2 liter Camry motor. It was still quick, agile, and moreover, it was dependable and sturdy as an anvil.

By the same token, the "powerful" but mild 265 cid V-8 that came in the 1955 Impala, was so much more impressive when dropped in the Corvette of that time. And that before the fuel injection, and solid lifters.

And let's not forget that the 4.3 liter OHV v-8 that powered the "hot" version the Ford Falcon, and the first v-8 Mustangs turned the AC Ace into a fire-breathing monster that became known as the AC Cobra.

Some very "pedestrian" motors from both sides of the pond have been instrumental in powering some very historically significant automobiles.

I understand that it's an interesting argument. But each side can prove its point and validity. But when the day ends and the cars are coming back to the pits to be loaded on the trialers, or driven home, the horsepower numbers won't mean anything. The torque numbers won't mean anything. The numbers that count, will be found on the stopwatches.
 
i dont mean handling as in posting large numbers, but in tactile feedback, nuance and response in the various systems, something the euros are, arguably, still the best at.

no dount the C4 was an good handler, but it showed GM the way forward, that they could make something worthy of competing with the euros if they finessed and fiddled with it. like i say, its what made the C5 such a giant leap in comparison to previous generations.
the vette has always handled well especially in comparison to american cars. C4 brought the numbers up to euro standards, C5 brought the tactility, C6 has NOTHING to be ashamed of. period.

but that slightly cheap feeling interior. which, in and off itself, is not too bad at its price point and for the perfomance you get, but its problem is that its constantly being compared to cars that are much more expensive than it is. this is when the interior comes up. this is the contrived achilles heel.
 
Not the ZR-1 without considerable difficulty. I've heard that only a few select GM dealers know what to do with them, and taking a ZR-1 anywheres else can mean death for the engine.
 
neanderthal
but that slightly cheap feeling interior. which, in and off itself, is not too bad at its price point and for the perfomance you get, but its problem is that its constantly being compared to cars that are much more expensive than it is. this is when the interior comes up. this is the contrived achilles heel.
Click to expand...
I have always thought that GM should offer a "Luxury Interior" package on the Vette to silence these comaprisons you mention. Sell it for $15,000 or something that will warrant the production at low volumes, and give people nice leather, wood/brushed metal, premium stereo, etc. The price would still undercut the competition!

But then again you could say that the XLR-V is in fact this package, and it hasn't found many friends.
 
That's because the XLR-v is a piece of crap when compared to the car it is supposed to be better than.
But I read something recently regading the 'Vettes interior: If GM would spend $5,000 per car to increase interior specs and ergonimics on the 'Vette they could charge $10,000 more per car and turn a profit.
 
...Ah, but then the Vette wouldn't be the value-priced supercar that it has always been, just another 911 compeditor. Whats so great about that?

In general, I would say that concerns over the quality of the interior materials are well founded in the Corvette, but it isn't like we are talking Kia-grade plastics here. They are still better, for the most part, than what you would find in your average American Civic or Corolla, those two cars often setting the benchmark in what is acceptable and what isn't.

Of the C6s I've been in, and driven, there aren't many complaints. Sure, the plastic grain could stand to be altered, or other materials used, but the interior is still better than the more-expensive Viper, and I think there is a general agreement there.

---

As for the XLR-V, its a good car. People don't like it because it costs too-much money, but praise it for it's performance and the ability it has to chase down the big-buck Bahn-Burners like the SL55. Okay, the interior isn't quite up-to-snuff, but in the context of General Motors, it was another step forward in the right direction.

Would I buy one against the Mercedes? Probably not... I just love the SL too much. But comparitively shopping between a Jaguar XKR and the XLR-V, thats a bit more difficult, as it is a more level playing field. But even then, I'd probably go Jag, as the XK is indeed one of my favorite models out there today.

...Oh, whats a GM fanboy to do?
 
I'd say $55,000 for a car with no faults (and is still far cheaper than any 911 of performance value) is far better than $45,000 with an interior that can be found in a 6-year-old Chevrolet Malibu.

On the XLR-v, my only problem with it is that it GM went and half-assed everythig with it. The SL was guaranteed to be better in refninment, so rather than try to outdo them in performance they instead target the 8-year-old Jaguar XKR and 10-year-old Aston Martin DB7 Vantage Volante. As soon as the new XK came out (Buick frot end aside), the XLR needed updating, and it didn't get it.
 

Latest Posts

Back