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Exhausting topics:single, dual, or dual with"X"
Posted 21 January 2011 - 10:46 PM
Posted 22 January 2011 - 02:18 PM
When you change the cams on these engines, then you can upgrade the exhaust system to take advantage of it, but I would go with single pipe.
Posted 22 January 2011 - 02:39 PM
So if you think about it, you essentially have 2 inline twins on a common crank.
Each side of the header would be tuned to each bank, and both sides would collect at the end of the exhaust pulse, and after the collector, it's all muffler and tailpipe.
Making the exhaust in an X configuration, at the same lenght as the cat in the factory y pipe(collector), you would have the same dynamic velocity/pulse/scavenge effect either way. From there you will hae a larger dump pipe, or 2 smaller dual outlets.
And this, having 2 outlets gives you the same volume of flow, but the skinnier pipes keep the velocities up.
In a true dual setup, you can run individual runners with no balance pipe, if not for the consideration of cats and o2 sensors.
This is what i come to with my understanding of exhaust dynamics, and with subarus.
A cam will affect the engines performance curves, but the exhaust piping itself is just fluid dynamics all on its own, regardless of the cam
Posted 24 January 2011 - 08:03 PM
i have also had gutted cat, 2" out from there, and had improvements....
had duals with crossover at 2", umm, had gutted cat, no cat, clogged cat:-p
i think it really depends on the condition of the engine as to what you should put on there.if you are rebuilding, go new crossover dual.an x is not really needed.
gonna stay carbed?or go spfi?there are a alot of factors i think....
complicated to hang is not true in my opinion, if you always base your crossover on the tranny hangerr that comes down.i have even made a few beefier mounts like that and bolted them to the tailhousing of the trans.there is room for some thin plate in there.
Edited by monstaru, 24 January 2011 - 08:11 PM.
Posted 25 January 2011 - 11:37 PM
Posted 26 January 2011 - 02:12 PM
(4.5-5k rpms max), of course motor isnt built for that, low torque! motor is runing a weber carb, delta torque gring cam, .75 over ea71 pistons, and big valve heads with work (ported and milled), and fresh everything to support it. but- going to a single exhaust, using a turbo maniflod off ea81/82?. but should give me more back pressure than i do now, maybe increasing the curve a bit. will post after drive it! sorry to ramble kinda...
Posted 27 January 2011 - 08:43 PM
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