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Chipster
Dodge Dakota
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10/21/2002
13:05:25
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 Subject: 4.7L HO Heads
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I was at the Truckin' Nationals this weekend.
Duner has put the HO heads on his turbo
setup. This is the deal. The HO heads have a
bigger chamber than the standard heads. So
with the HO heads you will have a bigger
exhaust valve, but less compression. Two
steps forward and one step back. Duner
doesn't have to worry about it because of his
turbo setup. Maybe the next step is the HO
domed pistions to bring the compression ratio
back up!!
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Duner
Dodge Dakota
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10/21/2002
13:20:34
| RE: 4.7L HO Heads
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It was very nice meeting you this weekend and lots of fun as well!
The HO heads and cam combination seemed to soak up a fair amount of boost but it looks like it put it to good use. The slightly lower compression should help me for on street use. I'm disappointed in myself for not taking the time to port the heads or at least clean them up a bit. I SHOULD have just installed the HO cams into my old heads to get an idea of what the HO cam did for me by itself. So much for the scientific approach! hahaha
My final best numbers from the weekend ended up being 12.46 @ 112mph or so. The timeslip said it was 136.83mph but that's not even close! (don't I wish) hahaha
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dr0p0ff
GenIII
 
10/21/2002
14:41:26
|  RE: 4.7L HO Heads
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what PSI were you pushing out there duner? you heading to glamis this weekend?!? 1st big weekend of the season!
Keep On Truckin!
Sgt G
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KRC Tech
Dodge Dakota
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10/21/2002
20:15:31
| RE: 4.7L HO Heads
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Duner, the block, heads and crank for the HO are different, but the rod and piston are the same for the HO as the NA 4.7L, at least that is what I have found out so far. The pistons sit in the hole differently than the regular 4.7L. Instead of moving the piston around for compression, they moved it's position in the block. Freaky. The actual compression on a reg 4.7L is 8.6 to 1, not what they advertise. Running the piston up to the deck at zero got me 9.3 to 1. The other thing I have found is that the Geroter oil pump does not like anything above 6000 rpm, especially on a manual shift truck. I have to run a external, way too expensive oil pump now. Which works out well with the oil gallery options in the 4.7L block. The pump cavitated at high rpms and the geroter broke. Talk to you soon.
Marty
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alex
Dodge Dakota
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10/21/2002
20:47:48
| RE: 4.7L HO Heads
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Marty,
So, are the rods longer in the HO, or are the pins in a different location? I dont' quite understand.... And how did you get the pistons in yours up to the deck? Are those customs rods in your application?
And that's good to know about the oil pump! Ouch. Didn't damage the motor finding out about that, did you?
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Duner
Dodge Dakota
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10/22/2002
00:45:24
| RE: 4.7L HO Heads
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Marty - Thanks for the info on the oil pump! Luckily I haven't been spinning mine much past 6k.....lately;>)
Sgt G - I was putting about 12-14psi to it. I'd love to head to Glamis but my honey-do list needs catching up since I spent last weekend at the race track. I really wanna get out there and spank some Banshees! hahaha
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KRC Tech
Dodge Dakota
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10/22/2002
08:24:33
| RE: 4.7L HO Heads
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The rod is the same, I believe the crank is the issue. The way I got the info is from ordering the parts between the two and finding out the piston rod combo is the same. The only rods are custom Crowers at the moment which cost around $800. The pistons I am having cut, for the moment are 3 different configurations I had Ross work. Blower, street and 11 to 1's, and none exceed .020 over due to the thin wall. When you shift manually, it severely jerks the geroter drive, causing it to snap. I'll dyno the 206/218 cams tommorrow, even with the modified intake, it should not have to go over 6000 rpm. The motor I have runs a 218/218 cam and a 4" runner intake. I will not have the dyno results for another month or two still getting it together. I try my best to break stuff here before letting the public race it. I am also tinkering with running a set of Nissan Eagle H-beams which are 6.0", essentially destroking the 4.7 slightly. The price is around $500 less than the customs and Ross can easily cut the pistons. The crack rods I have now did not hold up in the Wampler Durango once he exceeded 400 horsepower, but his torque, which I don't have, is probably the failure cause. I still will test the stock crack rods at 8000rpm. I have alot of faith in the newer powdered-metal technology. Later!
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Canucker
Dodge Dakota
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10/22/2002
12:55:25
| RE: 4.7L HO Heads
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Wow .. good stuff Marty. Keep it up!
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GlenC
GenIII
10/22/2002
15:31:15
| RE: 4.7L HO Heads
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Damn marty, good work. What i would give to come down there and help you out at the shop. It'd be so worth it to learn and experiment. Keep up the good work man, im just itchin to get some new parts in to push my dak like never before.
GlenC
'01, CC, SLT, 4.7, Auto, 3.55 LS, 4x4
MBRP cat back. JBA Headers. Kenne Bell supercharged.
My Truck
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