The Ford Barn

jan bogert · 10-21-2012, 07:46 AM

i hear some guys on here have ran thier flathead motors, with just straight exhaust, no mufflers. doesn't that hurt the motor without back pressure? JAN.

jimTN · 10-21-2012, 08:00 AM

no, running without headers might mess up a valve though. Plenty of straight exhaust cars running just fine.

KiWinUS · 10-21-2012, 08:05 AM

yep done it for years with no issues

rotorwrench · 10-21-2012, 09:26 AM

The length of the pipe helps in reducing the the exhaust pulses and a crossover pipe or H-pipe helps futher in smoothing them out with excelent exhaust scavenging. The exhaust in a flathead has to go around a few corners on the way out so that helps to smooth out the pulses. Extremely short header pipes would reduce the engines capability to scavenge the exhaust out of the cylinders and would put more heat on the valves, reducing there longevity to some degree. Mufflers are just there to lower the decibles a bit. Flathead engines don't bark quite as bad as OHV engines so a muffler is kind of optional depending on the owners taste for noise.

Some back pressure is more important for the overhead valve engines since the valves are dirrectly above the piston and have to endure more pressure and heat than those in a flathead plus the flow usually has less obstruction on the way out. They work a lot better with longer pipes and some form of muffler or expansion chamber keeps the law dogs from pulling you over to the curb.

ole39 · 10-21-2012, 11:08 AM

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fenton headers with 1 3/4 pipes on my 39. sounds great, and not as loud as alot of harleys.

10-21-2012, 07:46 AM	#1
jan bogert Senior Member Join Date: Nov 2011 Location: whitehall pa. Posts: 439	flathead exhaust i hear some guys on here have ran thier flathead motors, with just straight exhaust, no mufflers. doesn't that hurt the motor without back pressure? JAN.

10-21-2012, 08:00 AM	#2
jimTN Senior Member Join Date: May 2010 Location: Powell, TN Posts: 2,509	Re: flathead exhaust no, running without headers might mess up a valve though. Plenty of straight exhaust cars running just fine.

10-21-2012, 08:05 AM	#3
KiWinUS Senior Member Join Date: May 2010 Location: Charlotte NC KiWi-L100 available here Posts: 2,963	Re: flathead exhaust yep done it for years with no issues

10-21-2012, 09:26 AM	#4
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,436	Re: flathead exhaust The length of the pipe helps in reducing the the exhaust pulses and a crossover pipe or H-pipe helps futher in smoothing them out with excelent exhaust scavenging. The exhaust in a flathead has to go around a few corners on the way out so that helps to smooth out the pulses. Extremely short header pipes would reduce the engines capability to scavenge the exhaust out of the cylinders and would put more heat on the valves, reducing there longevity to some degree. Mufflers are just there to lower the decibles a bit. Flathead engines don't bark quite as bad as OHV engines so a muffler is kind of optional depending on the owners taste for noise. Some back pressure is more important for the overhead valve engines since the valves are dirrectly above the piston and have to endure more pressure and heat than those in a flathead plus the flow usually has less obstruction on the way out. They work a lot better with longer pipes and some form of muffler or expansion chamber keeps the law dogs from pulling you over to the curb.

10-21-2012, 11:08 AM	#5
ole39 Senior Member Join Date: May 2010 Location: west central ill Posts: 170	Re: flathead exhaust Sponsored Links (Register now to hide all advertisements) fenton headers with 1 3/4 pipes on my 39. sounds great, and not as loud as alot of harleys.