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Old 09-10-2010, 12:36 AM
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Exhaust question.

Hi, working on a 1964 vw bus with a header on it. Went from a 3 baffle muffler right out of the header to 18 feet worth of pipe with 2 magnaflow straight through mufflers. Pipe size and mufflers is 1 3/4. Did I add too much back pressure by adding this much pipe? I put the mufflers inline(one into the other one) Im just not sure if the more pipe you add, the more the back pressure will be. Goal was to get the mufflers away from engine and trans for room and ease to service valves and other stuff. Ran a lot better with the midas 3 baffle muffler on it. So I dont know if I now have too much backpressure or not enough. The exhaust is ran out of the header, runs back up to the middle of the bus, through each of the mufflers then back twards the rear. We used summit racing mandrel j pipes and cut them for the appropriate angles and welded them together.

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Old 09-10-2010, 01:16 AM
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I don`t think the more pipe you add the more back pressure, it`s more like the more bends you add and anything added in the exhaust system that will act as a restriction will add back pressure. Drive it, if it has good power and acts normal you don`t have any issue. However if it`s dead on power and is really sluggish, you have a issue.
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Old 09-10-2010, 02:01 AM
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yeah well I had more power with the single midas muffler just off the header. The 18 foot exhaust made it a lot less throttle responcive. As far as bends go theres a lot more bends and pipe than before so that makes sense, free flowing mufflers but too many bends. Lets see Ive got a 150 bend, two 90 bends, 3 or 4 45 bends. A buddy at work suggested that if it reves slower out of gear, that means I added more backpressure to it. I think hes right. Im gonna try using the 3 baffle midas muffler with one of the magnaflows and see how that goes for sound with a lot less pipe bends.
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Old 09-10-2010, 03:18 AM
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vwbus

not sure what you are trying to do there its a 64 vw bus these arent ment to go fast its a hippy bus if u want it to go fast weld up a new subframe and drop in a v8
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Old 09-10-2010, 07:41 AM
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Yes adding more pipe adds to back pressure. Not as much as a bend or restrictive muffler.

What you may have done is create less restriction which would move your peak torque and HP up the rpm scale. ie you may now have more high rpm and peak power but a little more of a dog right off the line.
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Old 09-10-2010, 02:04 PM
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Quote:
Originally Posted by wayneooo
not sure what you are trying to do there its a 64 vw bus these arent ment to go fast its a hippy bus if u want it to go fast weld up a new subframe and drop in a v8
hhehe funny. Thats what chevys are for. 50s to 70s muscle cars. Just because its not a v8 doesnt mean one cannot tune it. Guys at work keep saying drop a 911 motor in it. Fine go buy one for me lmao. Go fast is a very vague definition. I just want some decent power. Already have dual carbs on it. Made a big difference. Now I can cruise the freeway and maintain speed. Before, I couldnt even keep 60 mph on any slight slope. Running those annoying quiet pack mufflers that sit right under your valve cover when you are supposed to adjust your valves every oil change was just not functional.
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