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Discussion Starter · #1 ·
Checked some of the older posts on heads and don't really want to turn this into a full blown head discussion, But does anyone have first hand experience with the Hemi Design Heads and piston combination...
Thanks
 

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IME the Hemi Design heads and matched setup is a very good performer. A few around here have used them with great success. Problem is HP / dollar. Many are enticed into wringing the last drop out of a 95/98" and you have to admit with the cost of these parts you have entered the high-end 95" realm. IMO a conventional head 107 would be my choice, in this budget range but I do all my own labor, and I wouldn't look back. The heads could be ported by any of the majors, mild cams, and sensible compression. Much more sound and much more reliable wide torque band power.
That said if you want to persue the Hemi type chamber, another source more local and reasonable. great guy and very knowlegeable, would be Dave Mackie. Check him out. Ventura, Calif I think. He has a website.
 

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y a hemi

The true hemi chamber will flow exclent they can move a lot of air due to the wide open chamber.The problems are that there is no squish area or quench to cool the piston and make turbulance in the chamber. The large chamber requires a large dome on the piston even for 9.5-1 C.R. the dome interfears with the flow of the intake charge as well as the the combustion as it travels across the chamber.Dual plugs help a bunch.The cross flow hemi/semi hemi has some inherent problems some we can fix some not.That is why you see so many different style combustion chambers.I have worked with Hemi's since 1972.The true hemi is a pain in the butt for street use I much prefer a semi hemi like in the thunderstorm with @ 12 degree squish ? is the tc88 bathtub chamber considerd a hemi?
Al.
 

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They do open the head in the traditional style however the pistons have a tight quench area on the perimeter. All the hemi benifits and the squish issue is addressed.
 

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case2 said:
Checked some of the older posts on heads and don't really want to turn this into a full blown head discussion, But does anyone have first hand experience with the Hemi Design Heads and piston combination...
Thanks
Yes, the old Sportsters and Shovelheads had hemi heads from the factory. Harley abandoned them in favor of the more efficient D-chamber design. I had to use dual plugs to get decent ignition with them. With only one plug, they had a habit of burning only a portion of the mixture.
 

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I really like their idea...small hemi chamber with a flat top piston for good flame travel....and good compression...and a 360 degree quench area. Just wish the stuff wasnt so expensive. The old shovels and sportys needed dual plugs cause of the big domed piston....not an issue with these guys.
 

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The sporty and shovels had domed pistons but the quench was not tight. Their pistons look similar to the Axtell 30 degree units and they run tight. Dave Mackie does the same thing. No dual plugging needed as there are no dead spots on the chamber sides.
 

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Hemi/turbo/EVO

I just put AXTELL 97" all iron cylinders on my turbo EVO. They came with JE pistons and 10.5 to 1 compression. Needed to drop it to 8.7 so we ended up with a nice HEMI head. I am looking for hp around 145 or so at 10 " of boost. It should rock and roll. I am just putting it back together and it is in the frame but alot of things to hook up and build new exhaust. Friday in Ohio
www.dyno-power.com
 

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rabbit trails

case2 said:
Checked some of the older posts on heads and don't really want to turn this into a full blown head discussion, But does anyone have first hand experience with the Hemi Design Heads and piston combination...
Thanks
Well it looks like only one person has somewhat answered the guys question. So has anybody used the Hemi Design Heads?
 

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wkohn said:
Well it looks like only one person has somewhat answered the guys question. So has anybody used the Hemi Design Heads?
As I said before, yes, I have... Sportsters and Shovelheads. He didn't specify the "new" hemi heads. ;)
 

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ToddM said:
As I said before, yes, I have... Sportsters and Shovelheads. He didn't specify the "new" hemi heads. ;)
Let me help. I think he is wondering if anybody is using these heads www.hemidesign.com
 

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Al Taylor said:
I went to the web site. looks ok.Wonder if there are any detionation problems ?
With that much quench and flat top piston.....you'd have to really screw the pooch on cam selection to have a detonation concern with these heads and required matching pistons.
 
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Al Taylor said:
With the high angle squish and wide chamber someone might be a dog lover!
I see this thread is going to the dogs. :duh?:
 
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