4.2 inlets on a 4.5
Discussion
it's nice (in some ways) to have the injectors the other side of the butterfly but the 4.5 setup is nowhere near as flawed as it appears. Yes you get the fuel spraying onto the back of the butterfly, but that fuel has to pass through a very small gap on part throttle between butterfly and manifold wall, into an area of much lower pressure, and at very high speed through that gap. On full throttle the effect of the open butterfly in front of the injector is largely immaterial. What do you hope to gain by fitting manifolds with smaller butterflies but with an injector in the "correct" place ?
Some recent snippets on this thread if you can wait the results http://www.pistonheads.com/xforums/topic.asp?h=0&a...
I run the 4.2 set up, flowed but standard butterfly size, which at 45mm is not a lot smaller than the 46mm of the 4.5 set up. I make 450hp with a rebuilt 4.5 lump which proves they must flow enough for 450hp at least in my book. I suspect that at 470+hp they would start to struggle, although this has to be offset by the inherent crisper response of the 4.2 intakes lower down the rev range, all IMHO etc.
I run the 4.2 set up, flowed but standard butterfly size, which at 45mm is not a lot smaller than the 46mm of the 4.5 set up. I make 450hp with a rebuilt 4.5 lump which proves they must flow enough for 450hp at least in my book. I suspect that at 470+hp they would start to struggle, although this has to be offset by the inherent crisper response of the 4.2 intakes lower down the rev range, all IMHO etc.
HarryW said:
Some recent snippets on this thread if you can wait the results http://www.pistonheads.com/xforums/topic.asp?h=0&a...
I run the 4.2 set up, flowed but standard butterfly size, which at 45mm is not a lot smaller than the 46mm of the 4.5 set up. I make 450hp with a rebuilt 4.5 lump which proves they must flow enough for 450hp at least in my book. I suspect that at 470+hp they would start to struggle, although this has to be offset by the inherent crisper response of the 4.2 intakes lower down the rev range, all IMHO etc.
When i measured my 4.5 they measured 48mm.I run the 4.2 set up, flowed but standard butterfly size, which at 45mm is not a lot smaller than the 46mm of the 4.5 set up. I make 450hp with a rebuilt 4.5 lump which proves they must flow enough for 450hp at least in my book. I suspect that at 470+hp they would start to struggle, although this has to be offset by the inherent crisper response of the 4.2 intakes lower down the rev range, all IMHO etc.
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