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| JT |
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not it's 1hp gain over the high flow cat.. so no cat is 6hp up on the factory item. AND that is on a 1600cc not 5000cc.
I agree, running no cats is definately not the performance gain I would expect! For sure. But I wouldn't go so far to say you can gain power from having one.. 
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| XR9UTE |
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Yes but the CAT's on a 5000cc engine are much larger in the first place and there's two of them. An increase in torque is a performance gain isn't it?
Anyway this discussion stems from your statement that you somhow had some performance gain that made up for inadequate heads by not having a MAF and CAT's. This is simply not the case. Pete. |
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| JT |
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ah yep I see, fair call.
yes it's off topic. But I was by no means trying to justify use of crappy E7's because I wasn't runnning cats  no no, I was just mentioning them so I could try and gauge whether my build is on target for what I want.
shouldn't have ever mentioned the cats!
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| JT |
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....just got the heads back from being ported.. they are actually E6's ?! whats the difference between E6 and E7 heads?
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| XR9UTE |
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Yes E6's are much worse than E7's. Hence the reason that E7's exist;
They have a ridge in the combustion chamber to create swirl but because it's cast iron the only thing it creates is detonation. Hopefully your mate has lopped off the ridge when polishing the chambers? Pete. |
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| JT |
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The short side radius has been smoothed out, casting marks, and the air injection port boss has been removed.. we weren't going to touch the combustion chambers...
where abouts is this ridge you speak of? 
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| BOTTLEDUP |
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From what I can see there... I don't know why he bothered. I doubt you'll see any meaningful power increase from the small amount of blend work he's done.
That big ridge in the centre of the chamber (bottom pic) is what XR9 is referring to... all those sharp edges are prime sources of detonation, you'd do better to concentrate on the chambers rather than the ports.
_________________ TE50 T1 P01 |
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| JT |
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well he's been porting heads for quite some time, always found old ford heads to have a terrible short side radius and he's had good gains on the flow bench just address this area alone. The 302w heads were almost as bad as the old 2L SOHC in the shortside radius.
also, most Performance Engine Tuning books for the 5.0i support porting concentration on this area.. I'll see if we can smooth out that ridge, but it doesn't look like much there between the valves.. 
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| XR9UTE |
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See the bit that plunges in between the valves....that's the ridge. Lay it right back or you'll be sorry. E7 heads have that part completely eliminated.
Cheers, Pete. |
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| JT |
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oh.. you mean this bit? (in red)
how far back should I take it? ...don't suppose anyone has a pic of an E7 (should just buy the alloys now lol  )
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| XR9UTE |
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That be it.
Take it back so it's a straight line across the chamber. |
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| JT |
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Ok,
but that would significantly lower the compression ratio? ie. depending on how far back to take the ridge.. 
Last edited by JT on Tue May 29, 2007 8:03 pm, edited 1 time in total. |
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| XR9UTE |
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It could add a few CC yes. Mill the heads to make it back up or better still use zero deck or even poke the pistons slightly out of the hole say 0.005".
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| JT |
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ah I see... damn they are quite different eh..
found this photo, you can see the entirely different shape, if I take the ridge all the way back it will be way out on compression as the E7 doesn't have the room around the plug like the E6. ...what to do? Wish I'd know this before getting them ported lol
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| JT |
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...looking at some Edelbrock heads I noticed they have a ridge? 
I know they are alloy so it gets rid of heat better but that doesn't mean that sharp alloy edges wouldnt cause detonation as well.. |
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