[genius7]

Hello,

it's been quite some time that I'be been wondering how come Ford is able to squeeze 460hp output out of its 5.0 litre engine while Chevrolet and Dodge need 6.2 and 6.4 litre engines to get similar output, 455hp and 485hb, respectively?

Also, Dodge's 5.7 litre engine option for Challenger is worse off, it produces only 375hp and lower torque than Mustang with its 5 litres => 410 ft-lb vs 420 ft-lb.

Could someone knowledgable please explain this to me in words of one syllable?

Thanks

[HCI2000SS]

Dual overhead cam vs pushrod design

[genius7]

Too plain of an answer. Could you please elaborate thereon?

[Walt88]

It has to do with airflow, a dohc motor has a 4 valve head. Four valves will have more overall curtain area than 2, and due to the nature of DOHC those engines will rev higher. So more airflow + more RPM means more power per given displacement

[ZRacerLE]

Originally Posted by Walt88

It has to do with airflow, a dohc motor has a 4 valve head. Four valves will have more overall curtain area than 2, and due to the nature of DOHC those engines will rev higher. So more airflow + more RPM means more power per given displacement

Exactly. The benefit of the single cam pushrod design is simpler, lighter, lower cg, and smaller engine for the same output. (I'm speculating here -->) A drawback is that there's less you can do with the valve timing so it's less reliable with high boost (?).

[Laststandard]

The 'vette LT1 is basically identical and rated at 465hp

[oldman]

HP per liter is a MEANINGLESS metric

[RobbyBeefcake87]

Originally Posted by genius7

Hello,

it's been quite some time that I'be been wondering how come Ford is able to squeeze 460hp output out of its 5.0 litre engine while Chevrolet and Dodge need 6.2 and 6.4 litre engines to get similar output, 455hp and 485hb, respectively?

Also, Dodge's 5.7 litre engine option for Challenger is worse off, it produces only 375hp and lower torque than Mustang with its 5 litres => 410 ft-lb vs 420 ft-lb.

Could someone knowledgable please explain this to me in words of one syllable?

Thanks

Different engine designs. Pushrods like the 6.2 and 6.4 make power being able to have and make use of a large displacement in a relatively small package. The 5.0 is a dual over head cam taking advantage of more efficient but much larger heads and cam designs. There's obviously more to it, but you can google that your self for a more in depth explanation of the difference.

It may surprise you to know that the small 5.0 is larger than the big 6.2 in actual physical size instead of internal displacement.

I hope it was a genuine question and not a Ford troll, because this question is not even a good troll attemp at this point lol.

[SFHess]

Not to mention that horsepower is a calculated number (HP=(torque x RPM)/5252).

The Mustang makes peak horsepower at 7000 RPM where HP is 1.33 times torque.

The Camaro makes its peak horsepower at 6000 RPM where HP is 1.14 times torque.

The fact that it revs higher means it can make more horsepower even though it makes less torque.

I remember hearing somewhere that the only difference between the 707 hp and 717 hp Hellcats was they moved the rev limiter up by 100 rpm.

[Mountain]

As others have said, it simply comes down to the amount of airflow you can get into the combustion chamber...

First, off, intake manifolds and exhaust are designed around a specific RPM power band. This has to do with the flow rate and the resonance tuning associated with the airflow. In basic, intakes and exhausts, those that are not "active" (which is most; being static in design), can only be designed to compliment a specific, set RPM range of an engine.

Things like cylinder head port sizes, valve size and valve angle also support the above in that engine RPM range.

Camshafts are really the "make or break it" items in an engine as they have the major dictation on how much air can get into and out of a combustion chamber, when and how efficiently. Variable valve timing (VVT) only augments a camshafts ability over different RPM ranges.

The more camshafts you have, the more you essentially have control over an engine's power output through engine RPM. Add in VVT and you only increase that capability.

Something like a "Hemi" 6.2L/6.4L or "LT1" 6.2L, being cam-in-block ("OHV"), has to rely on one (1) camshaft to control air flow events into and out of the combustion chamber, with VVT doing it's best to widen capability. The valvetrain design layout doesn't allow for too high of RPM stability without getting into expensive materials. The general idea here is to use somewhat large displacement to cover lower-range and mid-range power well and design the camshaft to bridge the gap between mid-range and high-range (dependant on vehicle application and transmission). In something like a Ford "Coyote" 5.0L/5.2L, being over-head-cam ("SOHC"; "DOHC") you have 2-4 camshafts to finer tailor airflow into and out. The design layout of this valvetrain also allows for very good high-RPM stability without high cost. The addition of VVT also an even wider control through RPM ranges. The idea here is to utilize smaller displacement with the high-RPM capability for peak numbers, design the base camshaft profiles to fit the main desired RPM range and vehicle application (type of car and transmission) and than adjust the cams with VVT to fill the other various RPM gaps. However, due to the lower displacement, your starting point is lower and there is only so much you can do with the airflow to make power.

This is why you see, in something like a Ford "Coyote", DOHC engines run higher RPM than competitors with OHV engines, like the LT1, yet both have similar peark power ratings. But if you look at the power curves, they are usually very different. Typically, a OHV competitor will have a broader power range over its operating range due to the large displacement; whereas a DOHC might have a broad power curve, many times not as much, but peak power and the power curve is much later in the engine's operating range.

There's a lot more to it, but that's my jumbled rant into answering your question.

[oldman]

The LT1 makes almost 2x the HP per valve, 3.5x more HP per cam shaft. HP per liter = meaningless.

[Idaho2018GTPremium]

Originally Posted by oldman

The LT1 makes almost 2x the HP per valve, 3.5x more HP per cam shaft. HP per liter = meaningless.

It's only meaningless when you are comparing two different types of engines such as OHV vs. DOHC vs FI. Hp/liter is not meaningless when comparing the same engine types.

[genius7]

Thank you everyone for answering my question!

[ZRacerLE]

Originally Posted by Idaho2018GTPremium

It's only meaningless when you are comparing two different types of engines such as OHV vs. DOHC vs FI. Hp/liter is not meaningless when comparing the same engine types.

Agreed