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Discussion Starter #1
If someone was on a budget and had to choose between throwing a new cam in their 5.7 Hemi, or porting and upgrading the heads, which would give the greater gain in horsepower? Which would save more gas?
 

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Generally speaking, the cam swap. Unless the heads are not well designed, which the Hemi heads generally are. But MORE horsepower, and save more gas? :D

Head porting generally is about flow, more flow = more fuel = more HP. They aren't mutually exclusive, but making more HP usually comes at the expense of gas mileage to some extent. I think ported heads have an advantage, but the right cam will make more of a difference IMHO

A Guy
 

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Generally speaking, the cam swap. Unless the heads are not well designed, which the Hemi heads generally are. But MORE horsepower, and save more gas? <img src="http://www.challengertalk.com/forums/images/smilies/biggrin.gif" border="0" alt="" title="Big Grin" class="inlineimg" />

Head porting generally is about flow, more flow = more fuel = more HP. They aren't mutually exclusive, but making more HP usually comes at the expense of gas mileage to some extent. I think ported heads have an advantage, but the right cam will make more of a difference IMHO

A Guy
Lol, I know they'll both reduce gas mileage, I was just curious about which of them would do less damage to it.
 

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Hmmm, an odd goal. You could probably find a cam that will give you more gas mileage...and less HP, lol. Since "a cam" isn't a set thing, so many grinds possible depending on goals and equipment, it's hard to say a cam will do this, or that. Since ported heads will likely gain you less HP that the proper cam choice, they'd likely have less impact on gas mileage. But why bother? Let me do an expensive mod that will not give me the best benefit just to save gas mileage.

I think a not to radical cam that will gain you HP, and maybe more importantly an improved torque curve, is the way to go. If you keep your foot out of it, your gas mileage would not suffer too much. But if you want to get on it, the gains are there.

All things being equal, I think most will reply to do the cam (or both, lol).

A Guy
 

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Hmmm, an odd goal. You could probably find a cam that will give you more gas mileage...and less HP, lol. Since "a cam" isn't a set thing, so many grinds possible depending on goals and equipment, it's hard to say a cam will do this, or that. Since ported heads will likely gain you less HP that the proper cam choice, they'd likely have less impact on gas mileage. But why bother? Let me do an expensive mod that will not give me the best benefit just to save gas mileage.

I think a not to radical cam that will gain you HP, and maybe more importantly an improved torque curve, is the way to go. If you keep your foot out of it, your gas mileage would not suffer too much. But if you want to get on it, the gains are there.

All things being equal, I think most will reply to do the cam (or both, lol).

A Guy
Sounds like the best option to me too. I guess when the time comes I'll call up MMX and ask about getting a custom grind
 

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But don't go by me, I drive an automatic V6. Based on some peoples opinion, my car should be pink with hello kitty stickers, lol. Many more knowledgeable people will no doubt have more to say on this question ;)

A Guy
 

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the stock cam in the 5.7 is the greatest limiting factor.

These engines response well to a (properly matched) cam and tuning and then the rest from there adds to it.

The stock profile has a "dip" in torque ~ 3.2-3.5K rpm and then it picks up then runs out of breath by the hp peak at 5.2k. Beyond that, its just spinning and not making any more power.

A cam will wake up a 5.7 - after doing it, you'd never go back to a stock 5.7 and be satisfied
 
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So what kind of cam do I want? Hydraulic roller? Something around a 270? I'm looking to get a nice bit of lope at idle but not too much either, and tuned more for torque than top end.

Should I be upgrading my valve springs and seats in my head's? I'm told the valve seats are the weak links in the new Hemi motors.

About how much power can I expect to make with the cam and tune alone? What about if I did manage to afford a moderate head porting?
 

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So what kind of cam do I want? Hydraulic roller? Something around a 270? I'm looking to get a nice bit of lope at idle but not too much either, and tuned more for torque than top end.

Should I be upgrading my valve springs and seats in my head's? I'm told the valve seats are the weak links in the new Hemi motors.

About how much power can I expect to make with the cam and tune alone? What about if I did manage to afford a moderate head porting?
All Gen III Hemi engines are hydraulic roller lifter cam.

The 270 cam is too much for a 5.7, the 260 / 266 or 392 cam are better suited for the 5.7.

Valve springs are a must when going to any higher lift cam from the OEM 5.7 cams, Stronger pushrods are extra insurance as well.

Depending on the tune, RWHP gains are 35 - 50 on 5.7s. With SRT shortys or shorty headers, your gains are on the upper end of the range.
 

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Discussion Starter #11
So what kind of cam do I want? Hydraulic roller? Something around a 270? I'm looking to get a nice bit of lope at idle but not too much either, and tuned more for torque than top end.

Should I be upgrading my valve springs and seats in my head's? I'm told the valve seats are the weak links in the new Hemi motors.

About how much power can I expect to make with the cam and tune alone? What about if I did manage to afford a moderate head porting?
All Gen III Hemi engines are hydraulic roller lifter cam.

The 270 cam is too much for a 5.7, the 260 / 266 or 392 cam are better suited for the 5.7.

Valve springs are a must when going to any higher lift cam from the OEM 5.7 cams, Stronger pushrods are extra insurance as well.

Depending on the tune, RWHP gains are 35 - 50 on 5.7s. With SRT shortys or shorty headers, your gains are on the upper end of the range.
Well I was planning on going with long tubes and a Flowmaster American Thunder exhaust, maybe high flow cats too, along with a Diablo PCM and tune. Also planning on a Hellcat airbox, ported intake (a 6.1 intake if I can make it work), and a bigger throttle body (what's the ideal size?). And of course, an oil catch can setup. What kind of RWHP could I expect?
 

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Discussion Starter #12
How does the 392 can compare to a 260 or 266? I imagine it's a good deal milder and doesn't give as much in the way of HP gains?
 

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How does the 392 can compare to a 260 or 266? I imagine it's a good deal milder and doesn't give as much in the way of HP gains?
There's a number of threads on the forums with 392 cam swaps.
 

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My thoughts on the modern 5.7 engine. Yes its under cammed and has a strong emissions bend to it. It does have to comply with emissions but after the purchase and warranty expiration no one is looking.

Stick with a mild grind, the pistons are not up to a whole lot. In fact I believe every modern high-perf engine is a box of band-aids and to try to push it hard only results in broken parts, and Hemi parts just cost more.

I think its better to wait and put in a nice well built & thought out crate engine from a reputable builder with a good warranty (dyno sheet) and gives a good trade in value. I think you will be much happier in the long haul.
 

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But don't go by me, I drive an automatic V6. Based on some peoples opinion, my car should be pink with hello kitty stickers, lol. Many more knowledgeable people will no doubt have more to say on this question ;)

A Guy
LOL Hey my wife drives a car with hello kity stickers on. Nothing wrong with HK stickers on a car.

Ron
 

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