Interesting Article on the 5.7L Hemi Engine

[IDSmoker]

While I certainly don't claim to understand the majority of the information it contains, I'm sure that there are some people here who will get far more out of this Popular HotRodding Article.

I apologize if this is old news...

[lilguyhemi]

Great article, it's good to see the Chevy guys impressed with the engine.
....and it sounds like we will see alot of good things in the future FROM DC.

[MagnumFreak]

Definitely an article for the motorhead. good find though

[smackdaddy]

I find this bit interesting:

"The intake manifold itself met some pretty steep design criteria. Not the least was that it must not cause an excessive restriction to airflow. This requirement had to be met while keeping noise to a minimum and packaging the whole deal as compactly as possible. The resulting intake looks like a work of art for the end user and a nightmare for the tool and die maker. The system has a tuned length FROM the filter to the plenum and FROM here each port runner to valve is a tuned length. Computer modeling and dyno testing has allowed the ports, plenum and filter-to-plenum runner length and diameter/volume to be sized near optimally for a wide power band consistent with street performance needs. The end product proved capable of delivering cooler air than an aluminum manifold while only restricting the intake port 10 percent at full valve lift. That is about the same as a good aftermarket performance intake."

They also have a diagram of the intake mainfold.

That reconfirms my suspicion that the stock part may be the way to go.

[Tzar007]

I find this bit interesting:

"The intake manifold itself met some pretty steep design criteria. Not the least was that it must not cause an excessive restriction to airflow. This requirement had to be met while keeping noise to a minimum and packaging the whole deal as compactly as possible. The resulting intake looks like a work of art for the end user and a nightmare for the tool and die maker. The system has a tuned length FROM the filter to the plenum and FROM here each port runner to valve is a tuned length. Computer modeling and dyno testing has allowed the ports, plenum and filter-to-plenum runner length and diameter/volume to be sized near optimally for a wide power band consistent with street performance needs. The end product proved capable of delivering cooler air than an aluminum manifold while only restricting the intake port 10 percent at full valve lift. That is about the same as a good aftermarket performance intake."

They also have a diagram of the intake mainfold.

That reconfirms my suspicion that the stock part may be the way to go.

Indeed. Sophisticated engineering and CNC machining on expensive machines makes it tougher and tougher for aftermarket companies to do better. On my Lude for example, headers made by aftermarket are basically a waste of money. Yes, you may gain some power at a specific RPM range, but then you are losing somewhere else. Honda's got it right already across all the RPM range, there isn't much of a reason to change them.

The intake manifold of the Hemi is probably in the same category. They have done the best that was possible considering the available space.

[IDSmoker]

<snip>
They also have a diagram of the intake mainfold.

That reconfirms my suspicion that the stock part may be the way to go.

It certainly seems, FROM that article, that there aren't many gains to be found on the intake side of the horsepower equation.

At least there seems to be more 'wiggle' room on the exhaust side, and it sounds like there may be some real improvements to be gained FROM porting and polishing.

Of course, for the real cheap horsepower gains, the Magnum/300C are still stuck waiting for the hackers to "unlock" the new computers.

[Magnum_Man]

the cylinder head has more than enough flow potential to clear the 600-hp barrier and probably do it (relatively speaking) with ease.

Sweeeet!

[Rev.Hammer]

This is why the HEMI will be THE engine to beat... IF we can get DCX to come off of the @^$&^%#!! codes and programming!

[FOURTEEN]

I found the most interesting info was:

""If a modification is done that increases mass airflow, such as a cold-air package, the computer has to be reprogrammed accordingly. Fortunately, two companies, Squier Inc and Street & Performance are working on this now and already have what is needed for transplants of the Hemi INTO other vehicles.""

So, are we wasting our time with CAI and freer exhaust??

How about those two companies??

[a12bee]

Leave it to Popular Hot Rodding to turn a story about the Hemi INTO a chevy article.

[Fred]

The important job of damping out crank torsional vibrations is handled by a lightweight damper that serves double duty as a pulley for the serpentine belt.

Food for thought on an underdrive pulley...

[BrilliantBlackHemi]

True, but they are trying to compare our new engine to the staple LS1 platform and how it differs. Something many readers can identify with I guess.

They also almost beat a dead horse on the Speed Density vs Mass Air Flow issue, meaning the limitations of CAI and Exhaust benefits on Chrysler engines. I have to agree with them there. I was really hoping this new engine design under the Diamler watch would eliminate Manifold Pressure Control in favor of Mass Air Flow. IMO, this was/is a key performance issue with the LH V6 and Magnum V8 engines and largely why the aftermarket develops little for Chrysler.

[hemi operator]

Us Ram guys have been finding the same. There really just isn't much you can do to the Hemi to get more out of it because exerything is already maximized, so to speak. Some guys have found honest gains of 20HP or so with headers and getting rid of the restrictive stock "Y" pipe that the Ram comes with, but intake modifications don't do jack squat except change the noise, which is fine if that's what you want. I opened up my airbox a bit and love the way it sounds. However, you can follow the whole intake path FROM airbox to throttle body and there is no real restriction, except for some baffles inside the "air hat" (the box section right at the throttle body) and the couple of bends the duct makes. The only way to really get any more true power FROM it is to change the programming, and this is a very slow-to-develop area. Superchips makes a good programmer for the '03 Ram hemi that makes about 12-15HP more at the peak, and as much as 23-25HP more at certain rpm ranges. You can get a couple of HP FROM the traditional "CAI" and free-er flowing exhaust systems, but that's about it. Of course, a good supercharger kit will change everything!

Just for information, I'd suggest cruising around some of the Dodge truck forum sites like www.dodgetrucks.org or the Ram section of www.dodgetalk.com for Hemi info. There are guys there that have been tinkering with this engine since the '03 model year, so there's some good experience. There's a GROUP of guys in the 12's in the 1/4 mile with shortbed regular cab 2wd Rams.