Getting ready to test the new Dart 8.1 496 heads. We also have this sheet metal single plane manifold that will be later cast in aluminum and also a duel plane manifold. We will run the manifolds with a 850 carb but the manifolds will also be availible with fuel injector ports. I am also going to put a Mefi 4b on and run the stock efi intake.
Thread: NEW DART 8.1 HEADS
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11-11-2010 07:49 PMThe Michigan Madman
url]www.crockettmarineengines.com[/url]
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11-12-2010 02:17 PMNice! Are those cast iron heads(kinda looks like it in the pics)? Keep us posted on results. Do you have any flow numbers?
BobFull Throttle Marine
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11-12-2010 02:50 PM
Good Luck
Looks like a pretty cool intake set up there
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11-12-2010 04:30 PM
I've been keeping my eyes open for some 496 Alluminum heads to replace my stock merc heads when I refresh my Whippled 496. Raylar is the only one so far that I know of. Options would be nice!
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11-13-2010 08:44 AMYes Bob they are iron and they flow better than a fully ported stock head and these are right out of the box so there is plenty of room for porting. I ran this setup yesterday on a stock shortblock with just a cam change and made almost 600 HP. We are going to put the stock efi manifold on and a Mefi 4 today and run it.
The Michigan Madman
url]www.crockettmarineengines.com[/url]
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11-13-2010 06:08 PM
600 HP naturall aspirated, impressive, so what would we be looking at with a Whipple screw kit and CMI sport tubes? I'm a real gluttin for punishment,because it took Dustin Whipple 9 months to get my PCM to work with my motor.
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11-13-2010 10:32 PMThe Michigan Madman
url]www.crockettmarineengines.com[/url]
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11-14-2010 01:10 PMHere are the pics with the stock efi manifold.
The Michigan Madman
url]www.crockettmarineengines.com[/url]
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11-16-2010 09:18 PM
Talked to Don Hardesty @ Dart Machine works, and asked him if Dart had any plans to build any alluminum 8.1 (496) heads. His reply was if the demand is there they will build them. I don't know about any one else but I would love to change up mine for a pair of Alluminum performance heads. There lighter and run cooler!
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11-17-2010 10:49 PM
Don most of the 496 engines are closed water cooled so I don't think you will run much cooler with aluminum heads. You could get a little more agressive with the compression and timming with the aluminum heads but with the Mercury ecu you can't do that. Yes you could take 80 pounds of weight off the back end of the boat but that could hurt you more if you throw your center of gravity off.The Michigan Madman
url]www.crockettmarineengines.com[/url]
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11-17-2010 10:56 PM
NO, I boat in the Chesapeake bay, but with fresh water cooling alluminum heads should hold up well.
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11-17-2010 11:10 PM
Tyler, Your probably correct about the merc ECU. My boat has gained some weight in the back, when I added the CMI sport tubes,and then some more when I added the Hardin thermostatic oil cooler. The whipple suppercharger probably did't add any weight. If I were to have new heads ported and pollished that would help performance without reprograming correct?
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11-23-2010 12:16 PMTyler - How come the Merc MEFI 4 electronic control unit cannot be programed for more aggressive compression and timing? is this any different than the 500EFI ecu? - thought MEFI 4 was all the same?
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