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MikeD
Dodge Dakota
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2/14/2002
21:46:43
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 Subject: Hemi Heads
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I was just looking at some websites showing the old Hemi engines and got to thinkin. Why can't a company make Hemi heads to put on the 5.9 where someone can make a stock to Hemi conversion w/ the new hemi heads someone has made?
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CW
GenIII
 
2/14/2002
21:57:05
|  RE: Hemi Heads
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Message:
There is a Hemi convertion for the 440 big blocks. That is all I know about.
2001 RC 4.7 5sp 9.25" 3.92 LSD
Ported 68mm throttle body, IAT adjuster, 3" flowmaster cat back, TPS @ .76V, 4" cold air, Roadmaster active suspention, Removed Third cat. Electric fan Convertion, Awaiting HO cams.
Working on adjustable fuel pressure with return.
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MikeD
Dodge Dakota
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2/14/2002
22:00:59
|  RE: Hemi Heads
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Message:
What about 360's?
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buffalobobare
Dodge Dakota
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6/11/2003
17:41:09
| RE: Hemi Heads
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Message:
looking for help on a set of heads #1731528-1
THX
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jjj
Dodge Dakota
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6/11/2003
19:42:19
| RE: Hemi Heads
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Why would you want hemi heads?
A wedge puts out more HP on gas than a hemi. Also the dome on the hemi interfers with the flame front.
Jeff
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POWER HUNGRY
Dodge Dakota
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6/11/2003
22:39:02
| RE: Hemi Heads
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Message:
I don't know were you get the idea that wedge heads make more power than hemis.
1. The design of the hemi head allows for larger valves than a wedge head for a given bore.
2. The design also has a built in tumble design for the incoming air/fuel mixture allowing it to burn more efficiently.
3. The shape lends itself to less carbon build up.
4. The shape gives it a high thermal and volumetric efficiency than a wedge.
5. The centrally located spark plug allows for faster burn and less timing needed.
All of the above plus straighter runners allow it to breath better and generally a higher compression ratio than a wedge. All 4 valve heads are basicly flattened out hemis. In the fast/most powerful cars in the world (top fuel) beats the heart of a hemi, enough said...
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hemi
Dodge Dakota
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6/12/2003
16:33:12
| RE: Hemi Heads
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this is just a thought, but wouldn't the knew hemi magnum heads fit on a 360 magnum. they are both magnums and both are small blocks
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Anthony G
Dodge Dakota
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6/12/2003
17:28:49
| RE: Hemi Heads
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Don't the new Hemi's have 16 spark plugs? Try converting that to a magnum 5.9 system. Also the push rods angles are not the same. The lifters might not work well at that pitch.
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jjj
Dodge Dakota
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6/18/2003
20:02:37
|  RE: Hemi Heads
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I never said Hemi heads don't flow better, I said on gasoline wedge heads make more power.
Why do think DC didn't use the hemi head for ProStock. The quench chamber my boy, it's all in the quench.
Think long and hard, hmmmmmmm, on gasoline Chrysler always went with a wedge head.
Nitro is a different story. Hemi rules on nitro.
And yes the new designs are pentaroof not hemi wonder why, hmmmmmmmmm.
Flame front and quench.
Jeff
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FazDak
GenII
6/18/2003
22:10:54
| RE: Hemi Heads
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All good uses of engine and hemispherical terms JJJ but actually........untill recently the Hemi head was outlawed in Prostock. They do have Hemi's in ProStock now though.
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jjj
Dodge Dakota
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6/19/2003
16:31:38
| RE: Hemi Heads
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Chyrsler even said the B1 heads make more power on gas than a hemi.
Never remember them being outlawed, maybe the weight break years ago but not sure on the outlawed part. But I will be honest and admit I don't know that.
You have to remember, the hemi design has been around for what 50 yrs or so, and NO body used it since the 70's in racing or production. Maybe GM and Ford just felt it was easier to get it outlawed than build their own hemi.
The reason is the dome kills flame travel and on gasoline you can get better performance from a wedge type design. Not counting multi vavle etc.
Even in 2 stroke engine where it is a true hemi, you still need the squish band to keep the dome small enough and control the flame front.
I think the reason for the pentaroof is to keep chamber cc's down to a reasonable level, so the piston dome isn't too high. Among other things.
Even the old street hemi was hard pressed to beat a 6 pak and it had dual carbs, much larger valve, much better flow, practically headers all from the factory. All the 6 pack had was trips, no headers, etc.
jeff
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JJJ
Dodge Dakota
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6/19/2003
16:50:17
| RE: Hemi Heads
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I just did some minor research and can't find where hemi heads are outlawed in Prostock.
In the 70's till 82 they did have an unfavorable weight break but after 82 the rules make no mention of chamber design other than 2 valve, single pushrod design and oh yeah has to have a manu. part # on.
Jeff
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