Car Engine questions

[Dari]

What's the difference between an inline 6 and V6?

Why do some engines like the 2.4L in the S2000 put have a high hp/L ratio than others, especially American engines like the Hemi and those found in the performance vehicles of GM?

Are there advantages/disadvantages of one kind over another?

 

[Red]

Originally posted by: Dari
What's the difference between an inline 6 and V6?

The cylinders are "in-line", in a row, while a V6 is in a... you guessed it, V configuration. Otherwise, V6's are smaller and require balancing while inline 6s are larger but harmonically balanced.

 

[phreakah]

here's the answer to your first question

 

[QuitBanningMe]

Duh
Head design
yes

 

[nakedfrog]

I would suggest paying a visit to howstuffworks.com
It all boils down to engines being built differently depending on what your goal is.
The S2000 may have a higher hp/L ratio, but the Hemi has torque in spades.

 

[Scarpozzi]

Inline configurations tend to be more dependable (due to the harmonic balancing), but V configurations take up less space and have better torque because they are able to have larger pistons from the space savings.

The Hemi design was based on piston firing order and material superiority.

 

[Tommunist]

Originally posted by: Dari
What's the difference between an inline 6 and V6?

Why do some engines like the 2.4L in the S2000 put have a high hp/L ratio than others, especially American engines like the Hemi and those found in the performance vehicles of GM?

Are there advantages/disadvantages of one kind over another?

choose 2 engines and it's easier to compare them. it's hard to make too many all-encompassing statements.

in the case of the S2000 engine vs the hemi....

S2000 advantages:
-takes up less space in the engine bay
-more effecient on fuel usage


hemi advantage:
-probably doesn't need 93 octane fuel (although i'm too lazy to check)
-more power overall
-less expensive


with those things being said the s2000 engine is certainly more advanced overall.

 

[Tommunist]

Originally posted by: Scarpozzi
Inline configurations tend to be more dependable (due to the harmonic balancing), but V configurations take up less space and have better torque because they are able to have larger pistons from the space savings.

The Hemi design was based on piston firing order and material superiority.

well - and the hemisphecrical head design

 

[nakedfrog]

Originally posted by: Tommunist
choose 2 engines and it's easier to compare them. it's hard to make too many all-encompassing statements.

in the case of the S2000 engine vs the hemi....

S2000 advantages:
-takes up less space in the engine bay
-more effecient on fuel usage


hemi advantage:
-probably doesn't need 93 octane fuel (although i'm too lazy to check)
-more power overall
-less expensive


with those things being said the s2000 engine is certainly more advanced overall.

You forgot to mention that the Hemi makes power below 5k RPMs

 

[jtvang125]

Yes, getting that much hp per liter is quite impressive but at the same time it's a really small engine, 2 liters. For these small engines to make that much hp, they have to be revved to very high engine rpms. And due to their size, torque output isn't that great.

 

[Tommunist]

Originally posted by: nakedfrog

Originally posted by: Tommunist
choose 2 engines and it's easier to compare them. it's hard to make too many all-encompassing statements.

in the case of the S2000 engine vs the hemi....

S2000 advantages:
-takes up less space in the engine bay
-more effecient on fuel usage


hemi advantage:
-probably doesn't need 93 octane fuel (although i'm too lazy to check)
-more power overall
-less expensive


with those things being said the s2000 engine is certainly more advanced overall.

You forgot to mention that the Hemi makes power below 5k RPMs

good point - i could also add in that the s2000 engine can rev much higher i'm guessing

 

[Demon-Xanth]

One thing that you must realize, is that HP/L is MEANINGLESS as far as an actual performance indicator. Chevy's LS7, weighs in at around 450LBs fully dressed. It's a 7L V8 with 500HP and 475LBft of torque. Redlines at something like 7000RPM. Honda's 2.2L in the S2000 weighs in at 370LBs, has 240HP and 162LBft of torque. It redlines at 8000RPM

The Chevy engine weighs in at 21% more.
The Chevy has 218% more displacement.
The Chevy has 108% more power.

Now, saying the Honda engine has a 1000RPM higher redline, 80LBs lighter weights, and 109HP/L sounds impressive. But you'd have to be a fanboy not to want an LS7 in an S2000

Moral: displacement DOES NOT equal weight.

 

[Tommunist]

Originally posted by: jtvang125
Yes, getting that much hp per liter is quite impressive but at the same time it's a really small engine, 2 liters. For these small engines to make that much hp, they have to be revved to very high engine rpms. And due to their size, torque output isn't that great.

i think comparing the s2000 engine and a hemi is kind of silly anyway - they are meant for very different applications and would both do pretty poorly in the others area of expertise.

 

[nakedfrog]

Originally posted by: Tommunist
good point - i could also add in that the s2000 engine can rev much higher i'm guessing

Yeah, but I don't know if it could be considered an advantage since it requires being revved much higher (9k RPM redline IIRC) to make power.

 

[Tommunist]

Originally posted by: Demon-Xanth
One thing that you must realize, is that HP/L is MEANINGLESS as far as an actual performance indicator. Chevy's LS7, weighs in at around 450LBs fully dressed. It's a 7L V8 with 500HP and 475LBft of torque. Redlines at something like 7000RPM. Honda's 2.2L in the S2000 weighs in at 370LBs, has 240HP and 162LBft of torque. It redlines at 8000RPM

The Chevy engine weighs in at 21% more.
The Chevy has 218% more displacement.
The Chevy has 108% more power.

Now, saying the Honda engine has a 1000RPM higher redline, 80LBs lighter weights, and 109HP/L sounds impressive. But you'd have to be a fanboy not to want an LS7 in an S2000

Moral: displacement DOES NOT equal weight.

well - it should take more material overall to enclose more displacement (especially when we are looking at 2x as many cylinders). you throw a heavier engine in the front of a small car like that and the handling will be fuct.

 

[psteng19]

HP/L ratio means nothing as far as I'm concerned (other than technical prowess).

HP is a function of torque and RPM.
The higher it can rev, the more hp it will make.
Generally it will mean max hp is made very high in the rev range, making for a very peaky engine with low torque down low.

An engine like that does not do much for the car itself, as a small block V8 will make more much usable power while getting the same, if not better, gas mileage.
The weight differences between those 2 engines will be negligible as well.

Some people like the F1 race car feel of revving to 10k RPM.
Others prefer chirping the tires in every gear.

 

[Demon-Xanth]

Originally posted by: Tommunist

Originally posted by: Demon-Xanth
One thing that you must realize, is that HP/L is MEANINGLESS as far as an actual performance indicator. Chevy's LS7, weighs in at around 450LBs fully dressed. It's a 7L V8 with 500HP and 475LBft of torque. Redlines at something like 7000RPM. Honda's 2.2L in the S2000 weighs in at 370LBs, has 240HP and 162LBft of torque. It redlines at 8000RPM

The Chevy engine weighs in at 21% more.
The Chevy has 218% more displacement.
The Chevy has 108% more power.

Now, saying the Honda engine has a 1000RPM higher redline, 80LBs lighter weights, and 109HP/L sounds impressive. But you'd have to be a fanboy not to want an LS7 in an S2000

Moral: displacement DOES NOT equal weight.

well - it should take more material overall to enclose more displacement (especially when we are looking at 2x as many cylinders). you throw a heavier engine in the front of a small car like that and the handling will be fuct.

Notice the weights listed in my description. The DOHC heads are very large, and very heavy, compared to pushrod heads.

Note: this is a Ford 4.6L DOHC engine beside a Ford 5.0 pushrod engine. The blocks are similar in size, but the heads differ by a very signifigant amount, to the point that the DOHC heads are about as large as the block.
http://www.vorshlag.com/pictures/motor-4.6-4V-004.jpg

 

[91TTZ]

Originally posted by: Demon-Xanth
One thing that you must realize, is that HP/L is MEANINGLESS as far as an actual performance indicator. Chevy's LS7, weighs in at around 450LBs fully dressed. It's a 7L V8 with 500HP and 475LBft of torque. Redlines at something like 7000RPM. Honda's 2.2L in the S2000 weighs in at 370LBs, has 240HP and 162LBft of torque. It redlines at 8000RPM

The Chevy engine weighs in at 21% more.
The Chevy has 218% more displacement.
The Chevy has 108% more power.

Now, saying the Honda engine has a 1000RPM higher redline, 80LBs lighter weights, and 109HP/L sounds impressive. But you'd have to be a fanboy not to want an LS7 in an S2000

Moral: displacement DOES NOT equal weight.

Exactly.

The thing people don't seem to be able to understand is that smaller engines inherently can rev higher and therefore have a higher HP/liter. The clueless seem to think it's due to "advanced technology", but really it's just basic physics.

That's like saying that a hummingbird can flap its wings faster than an eagle because the humminbirds's more advanced. It can flap its wings the fastest because it's the smallest bird. You can buy R/C car engines that rev to 40,000+ rpm. They're not advanced at all, but they're small so the small parts can change direction much faster.

 

[91TTZ]

Originally posted by: Tommunist

well - it should take more material overall to enclose more displacement (especially when we are looking at 2x as many cylinders). you throw a heavier engine in the front of a small car like that and the handling will be fuct.

That's not entirely true.

People always say this to put down Datsun 240Z owners who replace their 2.4L I6's with small block Chevy's V8's, but really the V8 is more compact.

 

[fbrdphreak]

1.) Well answered already by the HowStuffWorks page
2.) HP/displacement doesn't mean a whole lot by itself. The Honda 2.4L is a great engine, no doubt. Lots of power from a small engine that can be fuel efficient if you drive it. What you need to pay attention to is the power & torque curves. You will see on an engine like the S2000's 2.4L that relatively small amounts of torque are produced, and the curve itself will probably look like a steep mountain; starting out small and going up & up. Horsepower should be similar. At lower RPM's, there will not be much horsepower produced. As you break the 5-6K barrier, a sharp increase in horsepower should be present. In order to produce the power it does, the Honda engine has to rev very high. It relies on making less power per stroke (if that is the right terminology) but being able to rev higher at a faster rate.

Let's compare that to the Hemi. Eight cylinders versus four allows for significantly more amount of torque being produced, giving you a LOT more torque from even 1,500 RPM's. Horsepower will slope up as you go up the RPM's, but not a drastic amount. Torque itself will peak somewhere in the middle to upper RPM range (don't know the rev limit on the Hemi's), but overall stay fairly linear.

The differences in power and distribution are due to a lot of factors, not the least of which is number of cylinders. Other things are number of cams, head & intake manifold, & intake/exhaust timing. The Honda probably has more intake & exhaust valves which makes it more efficient than a four cylinder w/less valves; but to use that to its full potential and do more work per stroke, it has to rev higher and thus produce more power in the same amount of time.

In general:
V6: torquey with moderate HP, some engines like Honda's 3.0L V6 offer more high end HP than torque

I-6: good compromise of torque & HP

I-4: mainly mid to high end HP, less torque; an I-4 can generally be tuned to make up to 170-180 ft-lbs torque in the mid-range but only with larger displacement (2.2L or greater); or an I-4 can be tuned to make lots of HP but only at very high RPMs (i.e. S2000)

H-4: seems to be a good compromise of torque & HP, with an apparent advantage with forced induction (turbo or super charging)

V8: LOTS of torque with comparable HP; generally lower RPM but with torque available throughout the power band; can be tuned for high RPM and high HP with comparable torque, like the previously mentioned Chevy LS7 7.0L; small displacment (<5.0L) can be tuned to rev high and make LOTS of high-end HP

I hope this helps, and anyone please point out any flaws in my logic here; I'm no expert, just a guy who likes cars

EDIT

Forgot #3) HowStuffWorks explained advantages/disadvantages well. Of course there is the fuel economy issue and low-end torque versus mid to high-end power. The 3.3L V6 in my car makes about 180 ft-lbs @ 2500RPM (crappy, i know) and 150HP at 5200RPM. My gf's 2.2L I-4 makes 145HP @ like 6000RPM and maybe 140 ft-lbs @ like 3000-4000RPM. My car I can accelerate to 2500RPM in 1st-3rd gears and comfortably be at ~50MPH. She has to rev to 3000RPM or more in 1st-3rd to get to the same place. And even if my engine DIDN'T have 170K on it, she would still get better gas mileage than me. This changes a little with a V8. If you take a light-weight, aerodynamic vehicle (Vette) and put a V8 in it, you have the potential to get better gas mileage than a comparable V6. Staying with the Vette, it makes a LOT of low-end torque; with a manual transmission you could easily only rev to 2000RPM or less and get to 50MPH easily. Try the same thing with a V6 and chances are you will end up using more gas. I know this isn't 100% accurate as a lot of factors are present, but just look at EPA ratings:
Most V6 sedans today get 20MPG City, 28MPG Highway. A 6-speed Vette gets 20MPG City, 28MPG Highway. Much larger engine, pushing a car similar or slightly less in weight, getting the same gas mileage. In fact I've heard of people with 6-speed V8 Camaro's/Firebirds getting 21-22MPG City and 30MPG Highway.

Anyway, I think you get the idea

 

[91TTZ]

Here is a comparison between the 2.4L I6 and the Chevy 5.7L V8 in a small Datsun 240Z.

Datsun with 2.4L inline 6

Datsun with 5.7L V8

And a couple more shots from the other side:

2.4L I6

5.7L V8


I think these pics illustrate quite well the size difference. People picture American V8's as being huge and bulky, when they're really not. A modern pushrod V8 like the LS6 is a quality engine. It's external size is not much bigger than most 4 cylinder engines, with the block being slightly wider and the heads shorter. Its weight isn't that much more, either. But it's torque and power aren't even comparable. 7 liters, 500 hp, with an awesome torque curve. Low emissions.

 

[91TTZ]

Originally posted by: fbrdphreak


I hope this helps, and anyone please point out any flaws in my logic here; I'm no expert, just a guy who likes cars

I'd like to point out that torque has just about nothing to do with number of cylinders and everything to do with displacement. And the high end HP has more to do with the heads and how good they flow.

 

[fbrdphreak]

Originally posted by: 91TTZ

Originally posted by: fbrdphreak


I hope this helps, and anyone please point out any flaws in my logic here; I'm no expert, just a guy who likes cars

I'd like to point out that torque has nothing to do with number of cylinders and everything to do with displacement. And the high end HP has more to do with the heads and how good they flow.

Very good point. I guess I didn't really expand on that. The reason I said V8's generally make a lot more torque is not only because of cylinder's, but mainly because of the much larger displacement (usually 5.0L+)

Thanks

EDIT See my previous Edit also

 

[Zenmervolt]

Originally posted by: Scarpozzi
Inline configurations tend to be more dependable (due to the harmonic balancing), but V configurations take up less space and have better torque because they are able to have larger pistons from the space savings.

The Hemi design was based on piston firing order and material superiority.

So, so, so wrong.

An inline four is poorly balanced. Anything over about 2.0 litres without balance shafts will shake itself to death. Larger displacement V6 engines also require balance shafts to maintain smoothness.

Larger pistons do not make more torque. Actually, smaller diameter pistons with a longer stroke will give more useful torque. Large bore and short stroke engines typically have poorer low-end torque characteristics but can run to higher RPM since the shorter stroke makes the mean piston velocity at a given RPM lower.

The only engines that are inherently balanced are inline six/twelve/eighteen/etc engines, 90 degree crank V8 engines (almost exclusively American V8s, most foreign V8s are flat-crank), V12 engines, and any horizontally-opposed engine. A Subaru's flat-4 is far better balanced than an inline 4.

ZV

 

[smithdj]

Originally posted by: QuitBanningMe
Duh
Head design
yes

Sorry to add one more useless post to this topic, but QuitBanningME you are the fvcking pr!ck.