3000 rpm at 65mph?

[96eclipsegsx56]

Is it normal to be at 3000+ RPMs at 65+ MPH in 5th gear?

 

[DSM1G90]

Check with an external method (GPS or radar gun) to be sure.

I use the highway markers and the corner of the windshield and be visual on all of it. When I pass a mile marker, I hit the trip odo back to zero. when I hit the next mile marker, I'd better be at one mile on the trip odo.

Or, get a stop watch, put the car at 60mph and when you hit the mile marker, hit the button to start the countup. Then when you hit the next mile marker, hit the button to stop the count. You'd better be at 60 secs with stock tires.

Get the circumference specs of a stock 205/55r/16 tire and that should be real close to the tires you put on.

Check out this Tire size calculator. Works like a charm.



-DSM

 

[cliffkemp]

This is just the nature of small 4 cylinder engines. They have pathetic torque. This is why the adage of "there's no replacement for displacement" is perfectly sound logic that can not be beaten.

It is not the nature of 4 cylinder engines to have 'pathetic' tq. They actually have excellent tq based on displacement. The problem is, they are put into cars that are not proportionally heavier.

Ex. Dodge neon with 132 lbs of tq. and weighs 2500lbs.
Jeep cherekee 4.0 with 220 lbs of tq and weighs 3700lbs.

If they were 'pathetic' the jeep should have more than doubled the tq rating. I realize that some high performance engines today do have more than 2x the tq such as newer 3.5 and 3.7 and so fourth but, keep in mind that if you want to compare high performance engines, the s2000 had over 150 and the m3 just has 295.

Point is the m3 doesnt weigh at 2x the neon weight. The true saying should be there is no replacement for losing weight. A lotus with a 1.8 will tear up many cars on the road since the older exige could go 0-60 close to that of an m3 with the 414hp 4L v8 vs the little 1.8 toyota with just 190 hp and around 130 tq.

Our 2L are actually tq monsters for what they are with the right turbo set up. The real comparo will always be hp to weight ratio along with gearing and so on.

The best thing about our cars is having 500whp and getting 30+mpg...No v8 will ever do that even with good gearing like the zr1 and zo6....40 mph/1000 rpms will not even do it. Our cars can be made lighter than the v8 cars, too.

 

[Ozone302]

It is not the nature of 4 cylinder engines to have 'pathetic' tq. They actually have excellent tq based on displacement. The problem is, they are put into cars that are not proportionally heavier.

Ex. Dodge neon with 132 lbs of tq. and weighs 2500lbs.
Jeep cherekee 4.0 with 220 lbs of tq and weighs 3700lbs.

If they were 'pathetic' the jeep should have more than doubled the tq rating. I realize that some high performance engines today do have more than 2x the tq such as newer 3.5 and 3.7 and so fourth but, keep in mind that if you want to compare high performance engines, the s2000 had over 150 and the m3 just has 295.

Point is the m3 doesnt weigh at 2x the neon weight. The true saying should be there is no replacement for losing weight. A lotus with a 1.8 will tear up many cars on the road since the older exige could go 0-60 close to that of an m3 with the 414hp 4L v8 vs the little 1.8 toyota with just 190 hp and around 130 tq.

Our 2L are actually tq monsters for what they are with the right turbo set up. The real comparo will always be hp to weight ratio along with gearing and so on.

I think he meant at the time the engine actually produces the torque. 4cyl engines generally produce torque higher in the powerband than bigger engines.

 

[cliffkemp]

I think he meant at the time the engine actually produces the torque. 4cyl engines generally produce torque higher in the powerband than bigger engines.

That all depends on set up of cams, exhaust, and all. My neon put down 92% of its available tq at 2000 rpms. The tq curve was nealry flat til 5700 rpms, according to the dyno. It tapered off significantly above 6400 and it is a 420a DOHC engine. My point is, it depends on the weight of the car as to the performance you will get based on power (hp and tq.

This is why a lotus will do sub 5, 0-60, with a 1.8L making just 115 wtq and 165 whp. The more cylinders you put on an engine, the more inefficient it is based on displacement as it has more rotating weight within itself. Of any engine made, 4 cylinder engines have the highest power to displacement when NA and tuned. No matter how you slice it, the 4 cylinder is better.

The 'power' he was talking about when saying there is not replacement for displacement has more to do with what you feel. When you have a lot of tq, the car feels fast compared to a lighter car that may actually be faster. You will feel more 'ummpf' in a vehicle with an engine with lots of tq. That does not mean that it is accelerating faster.

I like big motors too....my favorite is the legend....426 hemi. Still, being 7L, it is not going to come close to the s2000 and make over 840, be street legal, and be drivable on the street like the s2000. This is why the s2000 has the record for hp/L. I will leave it at that. There is more to it, though.


Just to add. Porsche had a 3L 4 in the 968. It produced over 220 hp and tq. Size of the pistons and stroke all have much to do with when and where power is in the curve. Nobody puts big 4 cyl. engine in cars anymore but, they really are not all that big as a hemi has 213 CID per bank. That is 3.5L per 4 banger side. Same holds true with the zo6, it is a 427. Keep in mind that the porsche is just around 180 CID and factory tune. That porsche will put many v8s to shame when compared to when it was made although it was a semi heavy car.

 

[ramsack]

It is not the nature of 4 cylinder engines to have 'pathetic' tq. They actually have excellent tq based on displacement. The problem is, they are put into cars that are not proportionally heavier.

Ex. Dodge neon with 132 lbs of tq. and weighs 2500lbs.
Jeep cherekee 4.0 with 220 lbs of tq and weighs 3700lbs.

If they were 'pathetic' the jeep should have more than doubled the tq rating. I realize that some high performance engines today do have more than 2x the tq such as newer 3.5 and 3.7 and so fourth but, keep in mind that if you want to compare high performance engines, the s2000 had over 150 and the m3 just has 295.

Point is the m3 doesnt weigh at 2x the neon weight. The true saying should be there is no replacement for losing weight. A lotus with a 1.8 will tear up many cars on the road since the older exige could go 0-60 close to that of an m3 with the 414hp 4L v8 vs the little 1.8 toyota with just 190 hp and around 130 tq.

Our 2L are actually tq monsters for what they are with the right turbo set up. The real comparo will always be hp to weight ratio along with gearing and so on.

The best thing about our cars is having 500whp and getting 30+mpg...No v8 will ever do that even with good gearing like the zr1 and zo6....40 mph/1000 rpms will not even do it. Our cars can be made lighter than the v8 cars, too.

I'd take a heavy car over a lightweight parking-lot car. If your jollies are driving around a parking lot in twisty autocrosses, go for a light car. If you like real courses and don't want F1 aero tech for the downforce, then you want a heavy car. Losing weight is not a replacement for displacement.

Like hell a v8 won't get 30 MPG. Vettes do it with ease in their top gear.

The more cylinders you put on an engine, the more inefficient it is? I don't think so. How then, did F1 engines have the potential to make 1,000 naturally-aspirated HP from a 3 liter? Because it had 10 cylinders. It exposes that 3 liters to a TON of port area, and makes that power through RPMs. The gearing is way different than that of a road car, so at the wheels, they are still getting incredible torque numbers.

THAT still doesn't take over the "no replacement for displacement" adage. Those high speeds make an engine very unreliable.

 

[cliffkemp]

I'd take a heavy car over a lightweight parking-lot car. If your jollies are driving around a parking lot in twisty autocrosses, go for a light car. If you like real courses and don't want F1 aero tech for the downforce, then you want a heavy car. Losing weight is not a replacement for displacement.

Like hell a v8 won't get 30 MPG. Vettes do it with ease in their top gear.

BS and you know it. There is not a one vette that will get 30 mpg with just normal driving. NOT ONE. You would have to baby it going down the interstate all day to get that. The fastest cars on tracks have always been lighter ones.

If you want to go fast on a track that is long and set up for cars that have lots of power, by my guest. That is not skilled racing when you just dump the gas after a curve and go a couple of miles before the next serious turn. Havin to do hairpin turns, one after another, makes the driver focus more on the apex and requires quick judgement and more skill. Fact is, there is less room for error on shorter, low speed courses than longer highspeed courses. Look at the times. Proof is in the pudding. Just so you dont jump the gun, not saying larger, heavier cars are not that good either. I like both. For every corvette that has a 40mph/1000 rpm 6th trying to muster 30 mpg by putting at 65 in the interstate, I can find you PLEANTY of 4 cylinder cars that can do it no problem and beat it significantly.

To answer you F1 issue, that is easy. Tell me a street car that revs to 20k rpms....hmmm not any. When you can tell me ONE v8 that has the same tq/L or hp/L as a 4 cylinder, I stand corrected. F1 cars, for the record have very little tq but, they do keep what little they have to very high rpms and that is where the hp comes from. Hp is just work done over time. You have not proven any point about there is not replacement for displacement. Do keep in mind that F1 is going back to turbo 2L engines....wonder why that is???

 

[ramsack]

Normal driving or driving like an ass? They aren't gas hogs.

The fastest cars on tracks are those which are the lightest which also have more weight at speed (downforce). A piddly little Toyota Lotus is only good in a parking lot. It's not a high-speed car. If they had the aero tech for downforce, their engines wouldn't push them very far.

Ah yes, the common "this type of driving takes no skill" statement.

F1 is going back to small turbo engines because of idiot yuppie green tard eco-fascists having their way. There is zero technical reason why they are doing it. The cars will be slower. The same retards also believe that racing is 100% driver, so everyone must have equal cars. Sorry, but money is part of racing. People deserve to have better cars than others. It's just anti-competitive.

Since when is there a clause for "there is no replacement for displacement" that says this only applies to street cars. My F1 debate was to illustrate that even revs and cylinders don't meet up to the adage. You failed to understand gearing in that example.

Your whole side of the debate is picking and choosing facts that help it while ignoring the facts that hurt it.

There is no replacement for displacement.

 

[Ozone302]

BS and you know it. There is not a one vette that will get 30 mpg with just normal driving. NOT ONE. You would have to baby it going down the interstate all day to get that. The fastest cars on tracks have always been lighter ones.

If you want to go fast on a track that is long and set up for cars that have lots of power, by my guest. That is not skilled racing when you just dump the gas after a curve and go a couple of miles before the next serious turn. Havin to do hairpin turns, one after another, makes the driver focus more on the apex and requires quick judgement and more skill. Fact is, there is less room for error on shorter, low speed courses than longer highspeed courses. Look at the times. Proof is in the pudding. Just so you dont jump the gun, not saying larger, heavier cars are not that good either. I like both. For every corvette that has a 40mph/1000 rpm 6th trying to muster 30 mpg by putting at 65 in the interstate, I can find you PLEANTY of 4 cylinder cars that can do it no problem and beat it significantly.

To answer you F1 issue, that is easy. Tell me a street car that revs to 20k rpms....hmmm not any. When you can tell me ONE v8 that has the same tq/L or hp/L as a 4 cylinder, I stand corrected. F1 cars, for the record have very little tq but, they do keep what little they have to very high rpms and that is where the hp comes from. Hp is just work done over time. You have not proven any point about there is not replacement for displacement. Do keep in mind that F1 is going back to turbo 2L engines....wonder why that is???

I'm sorry but you're an idiot. You seem like one of those 4cyl fanboys that always says "volumetric efficiency" and shit like that to justify why 4 cyls are better. Volumetric efficiency is BS because at the end of the day the big v8 still has more power than you regardless of how much power per liter you're making. The only reason I own a 4cyl is because of gas prices. All I've owned since I was 16 was big v8's and honestly, I'm not very impressed with my 4cyl. So quit acting like 4 cylinders are the holy grail of engines, because they're not. They're just little economy engines that are tuned out the ass to be "the best of both worlds", when in reality they are not that at all. I'd rather have a nasty snarling v8 trying to twist my cars chassis than a little baby 2L trying to spool up half the time. There is no replacement for displacement.

 

[95TalonOwner]

I'm sorry but you're an idiot. You seem like one of those 4cyl fanboys that always says "volumetric efficiency" and shit like that to justify why 4 cyls are better. Volumetric efficiency is BS because at the end of the day the big v8 still has more power than you regardless of how much power per liter you're making. The only reason I own a 4cyl is because of gas prices. All I've owned since I was 16 was big v8's and honestly, I'm not very impressed with my 4cyl. So quit acting like 4 cylinders are the holy grail of engines, because they're not. They're just little economy engines that are tuned out the ass to be "the best of both worlds", when in reality they are not that at all. I'd rather have a nasty snarling v8 trying to twist my cars chassis than a little baby 2L trying to spool up half the time. There is no replacement for displacement.

Then get rid of your car and stop complaining? This is a thread basically about gear ratios.

Back on topic...

 

[Calan]

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[Archer Fabrications]

Im with you craig..... Are these rants even necessary? And what does it have to do with dsms and their 3000rpm 60mph 5th. Just
My $.02 if you guys wanna have a displacement war between dodge and honda take it to pm

 

[cliffkemp]

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I was about to post the BS that he sent me as I tried to be civil and all to him in a private message and explain to him what I was referring to...to no avail. This is not even worth it.

The topic is about gearing and I have owned 5 dsm cars and love them for all their quirks. I have had v8s and v6s too and even still have my rotary. My apologies for this getting out of hand as some people do not get the point and start to rave.

My original posts are accurate and tired of playing the peeing contest with people that do not get it.

I am actually putting taller tires on my laser and if the trans fails at some point, I will probably have the 5th gear redone to add to the mpg savings as I dont drive the car all that hard and it has a 2.3 to aid in low tq.

I also agree, if you do not like your car, sell it and get what you like, as stated earlier.

Im with you craig..... Are these rants even necessary? And what does it have to do with dsms and their 3000rpm 60mph 5th. Just
My $.02 if you guys wanna have a displacement war between dodge and honda take it to pm

I tried that, he was an idiot there too. Some people.....

 

[ramsack]

You're the tool who couldn't lose an argument publicly, so that's why you tried to take it to PM. And then you had the snarky attitude of an ass to facetiously wish me a good day.

There's no replacement for displacement.

Only asshole idiots will attack me for saying this because they will somehow view it as attacking these cars. I guess the people who stroke or bore these engines for displacement are also idiots. Otherwise, we should destroke them down to some absurdly small number to try to get the most HP/liter for no reason and say that breaks the rule of "there's no replacement for displacement."

 

[cliffkemp]

Then get rid of your car and stop complaining? This is a thread basically about gear ratios.

Back on topic...

Amen to that. The replacement to displacement is a turbo....2 or even 4 in some cars.

You're the tool who couldn't lose an argument publicly, so that's why you tried to take it to PM. And then you had the snarky attitude of an ass to facetiously wish me a good day.

There's no replacement for displacement.

Only asshole idiots will attack me for saying this because they will somehow view it as attacking these cars. I guess the people who stroke or bore these engines for displacement are also idiots. Otherwise, we should destroke them down to some absurdly small number to try to get the most HP/liter for no reason and say that breaks the rule of "there's no replacement for displacement."

You jumped the gun. I was not attacking you, only giving you facts. In public is not the place for this and you being an idiot and calling names just shows your ignorance.

The POINT was that 4cyl are more efficient and have more tq than you make it out to be as they are not anemic on this. As far as tq/L goes, 4cyl do much better. I never said that stroking an engine was a bad thing as I have one in my car.

I said have a nice day as in being decent, not condecending.

 

[ramsack]

Turbos are a replacement for displacement to the mechanically-ignorant. You can't just develop a high-HP N/A engine and then boost it. There are sacrifices to be made in many areas, and it's why "there's no replacement for displacement."

 

[ramsack]

4 cylinders are more efficient per mile, and being mounted in small tin cans helps. They are less efficient at turning the energy in fuel to rotational force.

 

[Archer Fabrications]

if i was a mod.......... id close this thread already you guys are pathetic and annoying

 

[Achelea]

Can an airplane mechanic join in?

Gonna explain a few things so everyone sees why I am saying what I say at the end. Good? Cool.

All 4 stroke reciprocating engines produce torque. For testing they build 1 cylinder engines to test designs of pistons, cams, cranks ect ect.

A 4 stroke motor goes through 2 complete rotations per cycle. Starting at TDC, you have the Intake stroke. It's at the bottom, and starts the compression stroke. Hey, it's at the top again, And there's the spark of our lives, the plug! And down again for the power stroke. Whew, that's hot, let's get rid of the smoke. Back up once more for the Exhaust. Top bottom top bottom top. 180 degrees each cycle, and 720 degrees total. IE 720 degrees of rotation per power stroke. (So technically, your car is only producing power on HALF the full revolution).

Why is this important? Because 1 Cyl engine, (Like they have on really old dirt bikes IIRC) are rough. They call them thumpers, because they have a power stroke on every other rotation, and they beat the piss out of you when you're not running it.

So that's 720/1=720 degrees between spark.

Well, to smooth things out, they put another cylinder on there, and golly gee, they found out you could put it just about opposite of the other one. So you get a spark every cycle. How far apart are they?

720/2(Cylinders)=360 degrees between sparks.

Cool. What about the 3 cylinder geo metro with it's anemic output but awesome fuel milage?

720/3=240 degrees between sparks.

You can see where this is going, right?

720/1=720
720/2=360
720/3=240
720/4=180
720/5=144
720/6=120
720/7=102.5 (this is so asinine, I don't think anyone bothered with this number personally. Well, except for radial engines, but I don't see a lot of round motors on our cars. )
720/8=90
720/9=80 (another round motor number. Old timey airplane engines)
720/10=72
720/11=65.45 (Why the hell do those old timers insist on these funky numbers... Oh, right, they were crazy. )
720/12=60
Bah, we'll skip down to the 16 cyl engines, and then the world record motors for giggles.
720/16=45
720/36=20. Yes. There is a motor with 36 cylinders. Lycoming built a 36 cyl engine that had a displacement of 127 liters and produced 5000 hp.
Course the Russians decided to out do us.
720/112=6.42.. 112 Cylinders. 16 rows, 7 banks, 383 liters (That's 23,931 CCs. Yes, that many.) , producing 10,000 hp.

Why add more cylinders? They found out that the more cylinders you had, the smoother the engine ran. Funny huh? Another thing they figured out was the orientation of the cylinders mattered too.

Ever wonder why a Subaru Idles so damned smooth with NO balance shafts? Cause Each piston has a mate going with it. An Inline motor has vibrations cause all their pistons are dancing up and down, and a V4 wobbles cause their cylinders are pumping up to the sides. (I'd mention round motors, but they are finicky.. and weird.) During Power on, they all do the job, but the flat motor will run smoother than the inline motor, but the V motor sits some where in the middle.

But there's a funny thing. A V6 with a 60 degree slant won't make the same power as a v6 with the same displacement as one with a 90 slant. Reason is engineering. To make use of the power stroke, the crankshaft has to be designed different, and the 30 degree difference between the motors makes it's effect known.

SOoo, after that rambling, what do I have to say?

There is no replacement for: Research for your application.

Big V8 motors produce more torque at the lower RPMs simply because there is more pistons to push down on. That's why they Are Great for Drag racing, towing, stump pulling, etc etc. And they can be tuned for mid range RPM runs. However, when you get into the higher RPMs, you find out that steel stretches like rubber, iron shatters like glass, and you need to invest in more undies when they let go. With large area pistons they have a lot of mass moving back and forth. They can take a lot of punishment, but it's difficult to make a 4.7 liter V8 take near 10k rpms for extended periods of time. Not with normal internals.

So What about our smaller displacement 4 cylinders? Well, smaller pistons weigh less, so they have a bit less inertia, so they can take being slung up and down a cylinder at 5-6k rpm a bit better than a V8 would.. and maybe for a bit longer. But since there is less piston to push on, we don't have the same torque down low. However, we can make up for it by spinning a tad faster than the V8s do. That's why they do great for commuter cars. No reason to be filling up 8 cylinders when 4 would do the job. Hell.. at cruise, 2 cylinders can do the job.... 1 would be too little. And silly.

Want the best of both worlds? Look at aviation. They need efficiency, light weight, and reliable power.

So they have Aircooled horizontally opposed 4 and 6 cylinders. Depending on aircraft, some have tiny soda can pistons, and others have paint can sized pistons.

But I'm comparing apples to Oranges again, aren't I....
And in the end, that's what you are doing when arguing about V8 vs 4 cylinders.

Want me to make another Apple/Orange post again?

 

[PieEyedPiper]

Great post.
Feel free to explain apples and oranges anytime.

I've always been curious about oiling a circular engine..

 

[ramsack]

Not only do more cylinders smooth out the rotation, but there is generally more energy being extracted from the fuel per rotation than with fewer cylinders, hence it is more efficient thermodynamically. Aviation adopted jet engines because they can approach 100% efficiency, where a reciprocating engine is quite pathetic and only really converting 20-30% of the energy in the fuel to mechanical force. The answer is clearly jet engines powering all cars.

 

[PieEyedPiper]

Not only do more cylinders smooth out the rotation, but there is generally more energy being extracted from the fuel per rotation than with fewer cylinders, hence it is more efficient thermodynamically. Aviation adopted jet engines because they can approach 100% efficiency, where a reciprocating engine is quite pathetic and only really converting 20-30% of the energy in the fuel to mechanical force. The answer is clearly jet engines powering all cars.

And they're circular!

 

[cliffkemp]

Can an airplane mechanic join in?

Gonna explain a few things so everyone sees why I am saying what I say at the end. Good? Cool.

All 4 stroke reciprocating engines produce torque. For testing they build 1 cylinder engines to test designs of pistons, cams, cranks ect ect.

A 4 stroke motor goes through 2 complete rotations per cycle. Starting at TDC, you have the Intake stroke. It's at the bottom, and starts the compression stroke. Hey, it's at the top again, And there's the spark of our lives, the plug! And down again for the power stroke. Whew, that's hot, let's get rid of the smoke. Back up once more for the Exhaust. Top bottom top bottom top. 180 degrees each cycle, and 720 degrees total. IE 720 degrees of rotation per power stroke. (So technically, your car is only producing power on HALF the full revolution).

Why is this important? Because 1 Cyl engine, (Like they have on really old dirt bikes IIRC) are rough. They call them thumpers, because they have a power stroke on every other rotation, and they beat the piss out of you when you're not running it.

So that's 720/1=720 degrees between spark.

Well, to smooth things out, they put another cylinder on there, and golly gee, they found out you could put it just about opposite of the other one. So you get a spark every cycle. How far apart are they?

720/2(Cylinders)=360 degrees between sparks.

Cool. What about the 3 cylinder geo metro with it's anemic output but awesome fuel milage?

720/3=240 degrees between sparks.

You can see where this is going, right?

720/1=720
720/2=360
720/3=240
720/4=180
720/5=144
720/6=120
720/7=102.5 (this is so asinine, I don't think anyone bothered with this number personally. Well, except for radial engines, but I don't see a lot of round motors on our cars. )
720/8=90
720/9=80 (another round motor number. Old timey airplane engines)
720/10=72
720/11=65.45 (Why the hell do those old timers insist on these funky numbers... Oh, right, they were crazy. )
720/12=60
Bah, we'll skip down to the 16 cyl engines, and then the world record motors for giggles.
720/16=45
720/36=20. Yes. There is a motor with 36 cylinders. Lycoming built a 36 cyl engine that had a displacement of 127 liters and produced 5000 hp.
Course the Russians decided to out do us.
720/112=6.42.. 112 Cylinders. 16 rows, 7 banks, 383 liters (That's 23,931 CCs. Yes, that many.) , producing 10,000 hp.

Why add more cylinders? They found out that the more cylinders you had, the smoother the engine ran. Funny huh? Another thing they figured out was the orientation of the cylinders mattered too.

Ever wonder why a Subaru Idles so damned smooth with NO balance shafts? Cause Each piston has a mate going with it. An Inline motor has vibrations cause all their pistons are dancing up and down, and a V4 wobbles cause their cylinders are pumping up to the sides. (I'd mention round motors, but they are finicky.. and weird.) During Power on, they all do the job, but the flat motor will run smoother than the inline motor, but the V motor sits some where in the middle.

But there's a funny thing. A V6 with a 60 degree slant won't make the same power as a v6 with the same displacement as one with a 90 slant. Reason is engineering. To make use of the power stroke, the crankshaft has to be designed different, and the 30 degree difference between the motors makes it's effect known.

SOoo, after that rambling, what do I have to say?

There is no replacement for: Research for your application.

Big V8 motors produce more torque at the lower RPMs simply because there is more pistons to push down on. That's why they Are Great for Drag racing, towing, stump pulling, etc etc. And they can be tuned for mid range RPM runs. However, when you get into the higher RPMs, you find out that steel stretches like rubber, iron shatters like glass, and you need to invest in more undies when they let go. With large area pistons they have a lot of mass moving back and forth. They can take a lot of punishment, but it's difficult to make a 4.7 liter V8 take near 10k rpms for extended periods of time. Not with normal internals.

So What about our smaller displacement 4 cylinders? Well, smaller pistons weigh less, so they have a bit less inertia, so they can take being slung up and down a cylinder at 5-6k rpm a bit better than a V8 would.. and maybe for a bit longer. But since there is less piston to push on, we don't have the same torque down low. However, we can make up for it by spinning a tad faster than the V8s do. That's why they do great for commuter cars. No reason to be filling up 8 cylinders when 4 would do the job. Hell.. at cruise, 2 cylinders can do the job.... 1 would be too little. And silly.

Want the best of both worlds? Look at aviation. They need efficiency, light weight, and reliable power.

So they have Aircooled horizontally opposed 4 and 6 cylinders. Depending on aircraft, some have tiny soda can pistons, and others have paint can sized pistons.

But I'm comparing apples to Oranges again, aren't I....
And in the end, that's what you are doing when arguing about V8 vs 4 cylinders.

Want me to make another Apple/Orange post again?

Thanks for the post. I totally understand what you said and tried to say it to the other guy. More pistons makes for a smoother operation and you will get more tq over all. I did say that per piston/L you will not get as much as you have more weight being thrown around and that makes for a less efficiency as I was referring to mpg as it went with the above comments on gearing and such. I tried to be reasonable and give some physics on the matter to no avail.

I agree that you will get more tq as a whole but, it is relative to what the engine is used for and the weight associated. If you put a z06 vs a 1.3L haybusa, tides turn but, only because of the F1 'effect' so to speak too. I tried to explain that tq is just force and v8s feel 'torquier, faster, all that good stuff' due to the weight relative that it has to move. Put that against a car with the same hp/lb ratio and they would be 'nearly' the same as one variable would be a constant now. Gearing, number of gears, rolling resistance, and aerodynamics would dictate the winning along with reation time. I tried to say the same thing without going into so much detail and, I got a little off track with the thread at hand but, was trying to relate it to mpg efficiency as many comments were about that and rpms which, to an extent, dictate mpg.

Not only do more cylinders smooth out the rotation, but there is generally more energy being extracted from the fuel per rotation than with fewer cylinders, hence it is more efficient thermodynamically. Aviation adopted jet engines because they can approach 100% efficiency, where a reciprocating engine is quite pathetic and only really converting 20-30% of the energy in the fuel to mechanical force. The answer is clearly jet engines powering all cars.

Chrysler tried this...20mpg at best going across the country.

 

[gofer]

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