Race mufflers with EVAC setup?

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You need to make sure there is sufficient flow to open the valves with any muffler you get. I don;t know of any, but I don't use evacs much at all.
 
I had Flowmaster 50s on my car with the header evacuations system and the back pressure caused the check valves to fail after a couple of years. This is generally what happens with a full exhaust system. Despite all the rumors the system will work, and work fine, with a full exhaust system, it just works less efficiently depending on how restrictive the mufflers are and at some point will cause the check valves to fail - and then it stops working...
I did some research on backpressure levels in various mufflers and was actually surprised at what I found. Most people equate "sound - or loudness" to a free flowing muffler but this is not the case. Flowmasters and others use baffles to create the loud sounds but this restricts flow and increases backpressure. The bottom line is that the best muffler is a straight through glass pack (or a straight through period if you can tolerate the noise). My findings steered me to the Dynomax Ultra Flo as the best flowing muffler that still has sound reduction. They are actually a tad more quiet on my car than the Delta 50s were and even at idle my hoses are pulling significant vacuum onthe breathers.
One other tip if you are running the header evac system - get in the habit of periodiclly pulling off the breather(s) with the car running and put your hand over the holes to check for vacuum. You should feel a steady pull of vacuum. If you feel pulses of vacuum and then pressure the check valves are shot. Better to find it this way that when everything starts leaking :)
 
even if it pulls at idle - any backpressure will add up and kill things at the top end.

when I dyno'd my 430 I ran them with 6" exhaust pipes into dual 55 gallon drum mufflers.
It pulled vac at idle but it lost all vac at the top of the pull - from about 4 grand up and that was with those big *** drums and 6" pipes
 
Thanks,these are a 1/3 on the price of the Borla,s I was looking at.Any vid clips with sound?

Only one I can find with phone right now

E5037C4B-7A29-496F-B70A-96F4AC5C2FA7-17396-00001523EDEF2A5F_zpsb56ec350.mp4



Troy
 
Same with me,, Dynomax Race Bullets.Work and sound well at a good price.
 
3 1/2 inch Bullit Muffler's with tailpipes and tips. Muffler's dump in front of rear. But I still have the tail pipes hooked up into the turn downs. The car is loud but it sounds like its is comming from the tail pipes because they are tied in. You can also feel the exhaust coming out the tail pipes. The evac system works great. And the police leave me go when I drive it on the street.
 
3 1/2 inch Bullit Muffler's with tailpipes and tips. Muffler's dump in front of rear. But I still have the tail pipes hooked up into the turn downs. The car is loud but it sounds like its is comming from the tail pipes because they are tied in. You can also feel the exhaust coming out the tail pipes. The evac system works great. And the police leave me go when I drive it on the street.

You sir are one sly Devil
 
I used to make a muffler that was a required muffler for a lot of oval tracks. they were called "lobak" mufflers, and lots of the cobra guys run them on there sidepipes. there an auger muffler with a large center tube which creates a sort of vaccume effect on the exhaust. there price is good and they can be found at speedway motors, summit and a few other places like that.
 
3 1/2 inch Bullit Muffler's with tailpipes and tips. Muffler's dump in front of rear. But I still have the tail pipes hooked up into the turn downs. The car is loud but it sounds like its is comming from the tail pipes because they are tied in. You can also feel the exhaust coming out the tail pipes. The evac system works great. And the police leave me go when I drive it on the street.
nice idea, i may have to borrow your modifications.... you running an alternator? where ya hiding it?
 

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Better yet... consider getting a vacuum pump. Much better performance and end results than those check valves. There a track tested solid two tenths improvement. I have had one on my amx for the last 10 years and its been working great.

Then run any muffler you would like.
 
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