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Basic_Speed
Dodge Dakota
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3/24/2003
23:39:21
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 Subject: porting the heads
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I have a Dakota 5.9 R\T 1999. Iam in the process of upgrading the air flow. Mopar performance intake manifold, JBA headers, Mopar performance computer. The Question comes with the heads.
I am having them ported and polished; however, I am undecided on the type of porting to have done.
There are a few options: 1) budget porting only takes the bumps out and matches the intake gasket. 2) Performance porting opens up the airways throughout the heads, however this could effect the street drivability. This is where the question comes in: Is the Mopar performance computer going to be able to adjust for the incresed CFM now flowing thru the heads or is it just going to overload the engine? If it does the later will I be able to enlarge the injectors? That almost covers the question.
But I will stop for now.
Hope to see you out at the 1\4.
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brianman
Dodge Dakota
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3/25/2003
01:40:09
|  RE: porting the heads
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watch out you dont get the ports paper thin and also usually you want to get bigger valves but the magnum heads chamber shrouds the valve too much so it has to be cleaned up aswell as going bigger may hit water. they are junk heads but good in theory. you may not lose to much low end it may actually help take out the bottle neck and help low end. the flow increase shouldnt overload the computer as it is nothing too substantial. it would be wise to open up the exhaust and intake to take advantage of the heads but not go over board. i would check into the big valve magnum r/t head i havent heard to much about them though. as for injectors you probably wont need anyhting bigger maybe just flow matched. good luck.
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Brad
Dodge Dakota
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3/25/2003
08:41:37
| RE: porting the heads
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Had mine done for my 318. Because there isn't a whole lot of material to play with he basically smoothed everything out and downsized the valve guides. My results were 243 cfm at .500" on the intake and 180 cfm at .500" on the exhaust. We did find that they didn't want to flow over .5". So you might be better off with the r/t heads if you are looking into a high lift cam.
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brianman
Dodge Dakota
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3/26/2003
23:01:52
| RE: porting the heads
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blew the intake pan gasket on my truck so when it was pulled apart i had a look at the heads intake. they are a very poor design to start with. the intake is very crude inside and i see its very restrictive. but the ports are just crap. i hope the magnum heads are better.
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Brad
Dodge Dakota
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3/27/2003
08:32:56
| RE: porting the heads
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The heads are VERY deceiving! I thought the same thing when I got my heads off. Stock flow of my heads where 209 cfm at .5" intake and 160 cfm at .5" exhaust. Trust me I didn't believe it until I saw them tested myself. Even the guy porting the heads was surprised.
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POWER HUNGRY
Dodge Dakota
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3/27/2003
21:54:34
|  RE: porting the heads
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I don't know which years came with the 671 castings, but in High Perf. Mopar (sept. 97) they tested they against other small block heads. They found that they were better than most and has a strong .200-.450 valve lift flow average of about 185cfm.
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Daktrep9298
Dodge Dakota
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3/27/2003
22:26:23
| RE: porting the heads
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How do I tell which castings I have? I have a 5.9L out of a 95 Ram 1500. I was going to buy Magnum ported heads with the smaller valves but they flow 180cfm (I believe, correct me if I am wrong) So if I have the casting you mentioned, it should flow as well, correct?
Thanks
Dan
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Daktrep9298
Dodge Dakota
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3/27/2003
23:40:29
| RE: porting the heads
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Just found out that Mopar sells a porting template for the Magnum heads. It is part# P4876413. It was in the year 2000 Mopar parts catalog. Not sure if it is still around or not but I just found the part number.
Hope this helps
Dan
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POWER HUNGRY
Dodge Dakota
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3/29/2003
10:48:11
| RE: porting the heads
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Daktrep9298,
The ported Magnum heads #P4876257 Come with 1.97 int. and stock 1.625 valves and flow 230cfm @.550 lift @28". They say stock assemblies flow only 190cfms. The castings in the mag. flowed about 210 max. for the 671A and the 671B flowed 220 max. The casting #s are on the top of the center sxhaust runners. The magazine says the heads are 95-96 versions but didn't say anything about which are A castings and which are Bs.
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