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914World.com _ 914World Garage _ Megaphone exhaust on 4 cyl.
Posted by: krazykonrad Jun 19 2013, 07:52 PM
This may be my inner redneck talking, but how about megaphone exhaust pipes instead of a muffler on a 4 cylinder? Other than being loud, is there enough back pressure in the system?
Thanks in advance,
Konrad
Posted by: stugray Jun 19 2013, 08:26 PM
Just fired mine up for the first time since I started the rebuild (3 years).
It has a Kerry Johnson-style 4-into-1 and a single supertrapp with zero plates currently.
All the racecars run mostly open headers.
They all seem to run great, but they are definitely loud though.
One of the racers at RMVR took the stock HE tubes and merged each pair into one.
Then he put motorcycle mufflers on each set. It runs very well and isnt as loud as the other racecars.
Stu
Posted by: brant Jun 19 2013, 08:43 PM
twin megaphones, shouldn't work as well as a crossover or combined unit.
I've dyno'd both on a 6 but not back to back on a 4
Posted by: vw505 Jun 19 2013, 08:50 PM
Were can I find mega phones with the inserts like the one pictured above.
Posted by: spode Jun 20 2013, 12:13 PM
http://www.patrickmotorsports.com/part/exh-p9146-m18cc/
Posted by: Dave_Darling Jun 20 2013, 01:14 PM
I've seen one four-banger with stock heat exchangers (which may have had the "wrapping" cut off them) and a two-into one merge so each side had its own megaphone. No cross-over at all.
It sounded like crap to me. And I think it left performance on the table compared to any exhaust with a real collector in it.
--DD
Posted by: carr914 Jun 20 2013, 02:11 PM
Just fired mine up for the first time since I started the rebuild (3 years).
It has a Kerry Johnson-style 4-into-1 and a single supertrapp with zero plates currently.
All the racecars run mostly open headers.
They all seem to run great, but they are definitely loud though.
On my 4 Cyl Cars I ran Kerry Hunter Headers and on one I ran a HUGE SuperTrapp with Plates (came off a 935) - it loud as Hell
, set off every Car Alarm in 6 Story Parking Garage!
Were can I find mega phones with the inserts like the one pictured above.
GT Racing (but I'm sure you will have to buy a Pair
Posted by: SirAndy Jun 20 2013, 03:33 PM
Looks cool, performs badly, your choice ...
Posted by: Porsche930dude Jun 20 2013, 07:40 PM
iv got bus manifolds running into glass packs then into the the megaphone style tips you posted. i made them myself. I only have had it running a few days so its hard to say but first impressions doesnt sound very good. not crazy loud but you really only get the race car ear piercing sound with a race engine. I may end up making some sort of collector pipe across the back. time will tell
http://s2.photobucket.com/user/porsche930dude/media/porsche/bggbggg017_zpsf8f38d4c.jpg.html
http://s2.photobucket.com/user/porsche930dude/media/porsche/fgrd5y65002.jpg.html
Posted by: Porsche930dude Jul 19 2013, 08:34 PM
well that straight exhaust was terrible so i made my own muffler for it. i kept the bus manifolds and used a bus muffler. made extension pipes to the inlets. I cut an opening in the muffler so i could drill out the pipes inside it make it flow better. i cut open the baffles too. I ran the original single out exhaust pipe to one of my tips and cut a hole directly in the muffler for the second tip. so its a bit offset under the car. but it flows evenly both sides since I opened up the original tail pipe pretty good inside. and the tips are placed just like they were with the straight pipes. sounds good now not too loud but definatly not too quiet. just how i like it 
lots of cutting and welding and drilling but only took about a day and well worth the effort
Posted by: Jake Raby Jul 20 2013, 11:24 AM
Without a collector, these engines sacrifice a ton. I have never seen one that was tunable without a collector.
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