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-   -   ported exhaust manifold (http://www.jeepgarage.org/f183/ported-exhaust-manifold-32837.html)

inferno red wk 12-20-2011 07:51 AM

ported exhaust manifold
 
so the 4.7 has no headers available due to what i understand as lack of room does anyone think ported manifolds would make a difference i talked to the guy at gesslerheadporting he said he hasnt done a 4.7 exhaust manifold yet but his porting ussually weilds results around 10 to 15

mosier 12-20-2011 09:50 AM

Re: ported exhaust manifold
 
I was actually wondering this as well. I would think the biggest difference would maybe be for the Gen 1 4.7? Or did all generations of the 4.7 use the same manifolds? Thing is, it still looks like a nightmare to pull the stock one ones off, so I am not surprised that knowone makes any headers as there is just no room I can see what-so-ever.

05WK 12-20-2011 10:50 AM

Re: ported exhaust manifold
 
IF your manifold looks anything like the 3.7L I honestly don't think a little port job would increase 10-15. Due to the fact that none of the exhaust holes have their own pipe which causes exhaust fumes to travel into other cylinders which hurts performance. Porting the manifolds may increase flow but not fix the problem.

I'm basing this off if they are linear like the 3.7L manifolds.

mosier 12-20-2011 11:24 AM

Re: ported exhaust manifold
 
1 Attachment(s)
Here is a pic I have of the 4.7 Gen 2 if that helps.

05WK 12-20-2011 03:10 PM

Re: ported exhaust manifold
 
I tried posting that same picture haha

mosier 12-20-2011 03:36 PM

Re: ported exhaust manifold
 
:D. Really though, did'nt the Gen 2 come from the factory with high flow exhaust manifolds? If so, would'nt they just bolt up to the Gen 1 engines for a nice power increase?

jeepgcoman 12-20-2011 04:54 PM

Re: ported exhaust manifold
 
FWIW, I don't know anything about the 4.7's, but from the picture above, it looks very similar to the 5.7 exhaust manifold configuration.....maybe not quite as good. If the Gen. I and Gen. II 4.7 manifolds are as different as the 5.7 LX and the 5.7 WK units (see attached threads), I'd say you could gain a few horses. IMO, porting may help flow slightly, but unless you can increase flow substantially with larger collectors, you won't see a big difference. Also, they're "log" type manifolds that all dump into each other, causing obstruction/restriction in the exhaust flow. On the other side of that, considerably better/more flow may cause a slight loss of low end torque. When I put the Sidewinder cam in my WK, I advanced it 2* in an effort to offset this and gain a little more low end torque. When I do the Sidewinder on my LX, I am going to advance it 6*, as I think I can move the torque range lower yet, without sacrificing too much on the top. Main reasoning is that the only time I get above about 4000 RPM is when I am wringing it out or racing. Other than that it's always below 4000.

http://jeepgarage.org/showthread.php?t=19490 (See Post No. 1)

http://jeepgarage.org/showthread.php?t=18229 (See Post No. 8)

FlyinRyan 12-20-2011 07:19 PM

Re: ported exhaust manifold
 
Everyone complains about log manifolds, but it doesnt seem to stop folks from pushing 1000+HP out of them on turbo setups......

This isn't the 70s anymore. Particularly on a 4.7 the design itself is not terrible. The 5.7 is a different story.

Its been awhile since I was near a set of 4.7 manifolds, but I do think there is something to be gained out of porting them. I havent done a set but this is something I've been talking about for some time now.

The bigger issue with the 4.7 exhaust system is NOT the manifolds, but rather the downpipe. Headers/ ported manifolds, etc will do next to nothing if the downpipes are left as-is.

If the downpipe is re-fab'd, then yes, there would be something to gain out of porting. IIRC the manifolds are not well matched for the ports, so between port-matching and cleaning up the texture of the log, I think it would be worth it. You could ditch the cheesy heatshields they come with, take the time to ceramic coat them inside and out after porting, then wrap them up.

Best part is, they are OEM parts, so no emissions hassles....

As far as Gen 2 manifolds are concerned, I do not know if they will bolt up to a Gen 1 head. The Gen 2 manifolds are also poorly matched to the ports and could also provide some improvement. Yes, I've seen a Gen 2 manifold and cyl head up close. Even if the Gen 2 manifold bolts up to a Gen 1, it will likely need a custom downpipe made as I'm 99% sure they are different lengths/angles etc.

inferno red wk 01-02-2012 04:38 AM

Re: ported exhaust manifold
 
just got my ported exhaust manifolds back ill let you all no how they work

SoCalMoparWK 01-02-2012 08:16 AM

Re: ported exhaust manifold
 
hmmm...interesting...

FlyinRyan 01-02-2012 08:59 AM

Re: ported exhaust manifold
 
Pics?

inferno red wk 01-02-2012 08:32 PM

Re: ported exhaust manifold
 
nah i forgot to take them before i left when i do the intall ill do a comparison of the ports its one of those weeks ill tell yea


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