Why doesn't the 5.7 Hemi make more HP?

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RLJ10X

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I just saw that the 2018 Mustsng 5.0 is rumored to hsve 455. The present version makes 435. If they do in fact get 455, that is 91 hp per liter.

If the 5.7 Hemi did 91 per liter, that would be 518!

So why are we stuck at 395?
 

Ajwalk2008

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Restrictions in the exhaust and intake. It's all about making EPA standards. Plus your comparing apples to oranges i.e. Trucks and cars


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novelmike

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Restrictions in the exhaust and intake. It's all about making EPA standards. Plus your comparing apples to oranges i.e. Trucks and cars


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I'm so confused.....

If its intake and exhaust so i need a Carven muffler and a K&N intake? I hear those mods are not even noticeable on our trucks.


Yes, one is a truck and the other is a car. But they both are V8 motors. One can tow 10,000lbs the other doesn't even come with a tow hitch. So why does the vehicle that can't tow and cannot carry much weight have so more more horsepower?

I'm sure I'll be corrected if I am wrong; i believe a 2010 Ram had 390hp. So that's barely any improvement in horsepower in 7+ years.

Dodge-Ram-Chysler-Fiat, whoever you're called now....we need more power!
 

abouttobeglue

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My first truck was an ext cab 96 Z71 with 255 horsepowers, the 395 out of the hemi is a sports car compared to it, both were 5.7 liter motors. The better question is why don't they put the 485 horse 6.4 out of the charger into the ram.
 

crash68

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A possible reason on why sports cars vs trucks have the higher horsepower ratings is heat dissipation. There is only so much surface area to cool an engine block/heads with. It's easy to to dissipate short bursts of high heat. You pull a trailer on the freeway for a while, even though the engine isn't overheating, it does take longer for the coolant/oil temps to cool off.
Unless your circle track racing, your not going to be pushing that sports car, using most of those 485+ ponies for hours on end like you would with a truck towing a trailer.
 

BlakDak71

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They're two completely different engine designs.

The Hemi is a 16 valve, push rod V8. Sure, the heads flow well, but when comparing it to a 32 valve, dual overhead cam, high revving V8...apples to oranges. Cam profiles, compression ratio, bore x stroke, how high you can spin the engine while still making power all play a part in it.
 

ExpressRules

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I just saw that the 2018 Mustsng 5.0 is rumored to hsve 455. The present version makes 435. If they do in fact get 455, that is 91 hp per liter.

If the 5.7 Hemi did 91 per liter, that would be 518!

So why are we stuck at 395?


If you want the same output of the Mustang it is actually quite easy, install a catch can.
 

Riccochet

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If we're talking about HP per liter in a N/A application then why don't we have 684 HP when the Honda F20 makes 120 HP per liter in the S2000?

lol
 

2012Lamarie

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I just saw that the 2018 Mustsng 5.0 is rumored to hsve 455. The present version makes 435. If they do in fact get 455, that is 91 hp per liter.

If the 5.7 Hemi did 91 per liter, that would be 518!

So why are we stuck at 395?

I would be more interested in the torque ratings as well, we drive trucks. Comparing a car engine to a truck engine doesn't make sense. They are built for two different things. Also those new mustangs probably will get somewhere around 15mpg, in a vehicle that weighs half of our trucks. Put that motor into a truck and you get even less. There is more to it than just hp ratings.
 

2012Lamarie

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I'm so confused.....

If its intake and exhaust so i need a Carven muffler and a K&N intake? I hear those mods are not even noticeable on our trucks.


Yes, one is a truck and the other is a car. But they both are V8 motors. One can tow 10,000lbs the other doesn't even come with a tow hitch. So why does the vehicle that can't tow and cannot carry much weight have so more more horsepower?

I'm sure I'll be corrected if I am wrong; i believe a 2010 Ram had 390hp. So that's barely any improvement in horsepower in 7+ years.

Dodge-Ram-Chysler-Fiat, whoever you're called now....we need more power!

Are engines our tuned not only for hP and torque but also fuel economy. That mustang will get 15mpg with half the weight.
 

2012Lamarie

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A possible reason on why sports cars vs trucks have the higher horsepower ratings is heat dissipation. There is only so much surface area to cool an engine block/heads with. It's easy to to dissipate short bursts of high heat. You pull a trailer on the freeway for a while, even though the engine isn't overheating, it does take longer for the coolant/oil temps to cool off.
Unless your circle track racing, your not going to be pushing that sports car, using most of those 485+ ponies for hours on end like you would with a truck towing a trailer.

I get what you are saying but you are off. The HP rating has nothing to do with how much heat is dissipated. They don't test for HP and torque like that. It is a simple dyno test.
 

liftedgm1982

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They're two completely different engine designs.

The Hemi is a 16 valve, push rod V8. Sure, the heads flow well, but when comparing it to a 32 valve, dual overhead cam, high revving V8...apples to oranges. Cam profiles, compression ratio, bore x stroke, how high you can spin the engine while still making power all play a part in it.



This. Cubic inches and Liters do not equate to hp and torque.


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Csanders1992

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If I remember correctly those 5.0s don't hit peak power till super high in the rpm range. If we could spin our 5.7s that fast and still make power we could hit that number


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Juvenator93

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The current 5.0 in the F150 vs 5.7 in the 1500:
5.0
385hp @ 5750
387tq @ 3850
5.7
395hp @ 5600
410tq @ 3950


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mohemipar

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I don’t get this talk about the engine being underpowered. Will it beat a brand new Mustang with 455 HP, nope. That’s why I bought a 392 Charger…

These trucks are very powerful for what they are. They have no problem getting up and moving in any driving situation and are faster than the majority of your average car on the road even at twice the weight. We are talking about a 5500 pound truck that Chrysler built for people to put to work. Not drag race. The engine is designed for durability. If you want a racer, buy an R/T and do headers, cam, even put a blower on it if you like. It will be genuinely fast and will sound great. Maybe buy an Eco(haha)boost and see how it holds up after 10 years...or less. But it will sound like a vacuum cleaner. And the EcoBust is a gamble I would not be willing to take because I bought a truck to be used like a truck. Not to feel cool cus I can beat a Honda at a light.

The 5.7 Hemi is not Chrysler’s real performance engine, even in its sedan form. If you want that, you step up the 6.4 or Hellcat. And if you are buying something for true performance, why are you looking at a truck? You could mod a 5.7 Ram to the moon but it’s a totally different animal from your given example in your first post. That will never change no matter how much power Mopar decided to crank out of the 5.7.
 
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RLJ10X

RLJ10X

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The Hemi in a the Callenger makes even less HP than our trucks. So that comparison gets even worse.

If Ford can pass EPA, Dodge ought to be able to also.

Ever heard of the Pentistar? It is dual overhead cam, 4 valve per engine.

GM has managed to keep Thor schmancy new 650 hp 650 tq Camero cool.

There is no excuse.
 

crash68

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The HP rating has nothing to do with how much heat is dissipated. They don't test for HP and torque like that. It is a simple dyno test.

I know that's not how they dyno test an engine for HP. These engines are put in production cars, there is drive durability testing that the cars undergo. The manufacturer is not going to release are car that can cook itself to death. Over the years, engine tuning has probably been held back in lieu of long term durability. Or the ECM will de-rate the motor but the OEM can still claim the higher HP ratings.
 

mohemipar

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The Hemi in a the Callenger makes even less HP than our trucks. So that comparison gets even worse.

If Ford can pass EPA, Dodge ought to be able to also.

Ever heard of the Pentistar? It is dual overhead cam, 4 valve per engine.

GM has managed to keep Thor schmancy new 650 hp 650 tq Camero cool.

There is no excuse.

Umm, GM was late to the party. Hellcats can drag and drift non stop all day in 90+ degrees and not get heat soak. And they make more power. Ive seen it. And i do not dislike GM.
 

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