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Car Engine questions

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Originally posted by: Zenmervolt
A Subaru's flat-4 is far better balanced than an inline 4.
Click to expand...
Does that make them more stable to handle the boost of a turbo? 300HP @ the flywheel from a 2.2L(?) H-4 sounds pretty hefty
 
Originally posted by: fbrdphreak
Originally posted by: Zenmervolt
A Subaru's flat-4 is far better balanced than an inline 4.
Click to expand...
Does that make them more stable to handle the boost of a turbo? 300HP @ the flywheel from a 2.2L(?) H-4 sounds pretty hefty
Click to expand...


Not necessarily. That has more to do with how strong the engine is built. Also, turbo cars usually have a lot of torque instead of crazy high-end RPM.

Having a nicely balanced engine helps you rev high (like a F1 car), but it doesn't necessarily help it handle the torque. Having a free-revving engine with light parts isn't going to hold up well under a lot of boost.
 
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.
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I've never heard anything about piston firing order or material superiority. The hemispherical head IIRC had good flow characteristics, but the burn was pretty slow. (advance... advance... advance... KABOOM) 😛

ZV, I think torque (given the same volumetric efficiency) depends entirely on displacement. For example, the 3L F1 engines have to make about 230lb-ft of torque to make 900HP at 20kRPM (random numbers off the top of my head), while the stroke is extremely low to enable the engine to rev up that high.
 
Having owned at one point or another every flavor of engine (except a Hemi... Marketing crap anyway), I'll have to say my very favorite engine so far was the I6 in my 76 280z. I soooo wish I still had that car.

American V8s are sweet too, but they have to be built right. Typical 70's - 80's cars had the engines so detuned that they are jokes.

By far the smoothest engine was the one in my 78 Subaru. Pancake (boxer) engine, of course.
 
Originally posted by: Howard
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.
Click to expand...
I've never heard anything about piston firing order or material superiority. The hemispherical head IIRC had good flow characteristics, but the burn was pretty slow. (advance... advance... advance... KABOOM) 😛

ZV, I think torque (given the same volumetric efficiency) depends entirely on displacement. For example, the 3L F1 engines have to make about 230lb-ft of torque to make 900HP at 20kRPM (random numbers off the top of my head), while the stroke is extremely low to enable the engine to rev up that high.
Click to expand...
Nope, longer stroke will give more low-RPM torque for a given displacement with all else being equal. A couple of reasons: First, the crank throws are longer, which gives the piston more leverage on the crankshaft, second, smaller valves necessary for a smaller bore cylinder increase the intake and exhaust charge velocity, which aids low-RPM torque.

Now, a larger displacement engine will make more torque than a smaller one (all else being equal), but the bore/stroke ratio plays a huge part in torque too.

ZV
 
Originally posted by: smithdj
Originally posted by: QuitBanningMe
Duh
Head design
yes
Click to expand...


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

It was the correct answer (for the most part).

I'm not going to write a big long post for someone who isn't going to have any idea what the fvck I'm talking about.

Maybe if I typed faster .....
 
Originally posted by: Zenmervolt
Originally posted by: Howard
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.
Click to expand...
I've never heard anything about piston firing order or material superiority. The hemispherical head IIRC had good flow characteristics, but the burn was pretty slow. (advance... advance... advance... KABOOM) 😛

ZV, I think torque (given the same volumetric efficiency) depends entirely on displacement. For example, the 3L F1 engines have to make about 230lb-ft of torque to make 900HP at 20kRPM (random numbers off the top of my head), while the stroke is extremely low to enable the engine to rev up that high.
Click to expand...
Nope, longer stroke will give more low-RPM torque for a given displacement with all else being equal. A couple of reasons: First, the crank throws are longer, which gives the piston more leverage on the crankshaft, second, smaller valves necessary for a smaller bore cylinder increase the intake and exhaust charge velocity, which aids low-RPM torque.

Now, a larger displacement engine will make more torque than a smaller one (all else being equal), but the bore/stroke ratio plays a huge part in torque too.

ZV
Click to expand...
"crank throws are longer" If the stroke is reduced, the bore is increased. Still the same amount of torque.

"smaller valves" But I'd already stipulated the same volumetric efficiency, which is affected by the velocity of the flowing gases, no?
 
Originally posted by: Howard
"crank throws are longer" If the stroke is reduced, the bore is increased. Still the same amount of torque.

"smaller valves" But I'd already stipulated the same volumetric efficiency, which is affected by the velocity of the flowing gases, no?
Click to expand...
Increased bore decreases the stroke and thereby decreases the leverage on the crank. Long stroke means more leverage and more low-end torque.

Note that every single post of mine has specified _low end_ torque. Torque where it's useful.

ZV
 
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