Muffler vs Straight pipe

[jda50]

I just read a post on the John Deere discussion page about losing HP with a straight pipe vs a muffler. Anyone have any experiance with this? They claimed it was tested on a Dyno. I do a little pulling with a 1950 "A" and could use all the help I can get. Have a straight pipe now.
Thanks for any info---

 

[The Dukester]

I imagine on a tractor like your A or my '51 G, a straight pipe is not much of any help powerwise but it makes 'em sound powerful. Now if we were to soup our old Johnnys up with reduced restriction air cleaners, ported and relieved heads with big valves, a Denny's reamed out and screwed up carburetor, 2 inches more stroke and ran 'em at 1800 rpms, the straight pipe would be the way to go to keep the flow. See what I mean? Bottom line...with our old wheezers it don't make much difference powerwise.

 

[BushogPapa]

Anytime you reduce back-pressure, you may lean-out the mixture due to better breathing..
This would reduce power somewhat, but adding the necessary fuel back to it will certainly add the power back, if not make a little more..!

That Original exhaust is not "Tuned" for Max Power..!!
We had 2 New '52 JD "B" tractors and JD could not keep BOTH on the farm at the same time..Burnt Valves..until the Mufflers rusted off (1954).
Then, they never burned a valve since..!!

I am a believer in the reason to use a Straight Pipe..!!
HUH..??? Yes, I angle-cut the top toward the front to ease the crack on my ears..!!
It does help..!
Ron.

 

[james rumph]

In drag racing almost all run open headers .
We have found on bracket cars that adding a length of straight pipe to the collector adds power and better 60' times.

Now how do you figure out how much pipe to add to get the correct amount of back presure ?

Spray paint the pipes with high heat paint and make a pass. You will see a line ware the paint isn't discolored or burnt off that is ware you cut. We have been doing this for years with great results as well as the most important part "60' times" .

I did the same with my Super M on the dyno by starting out with a long pipe and working down.

So in short the straight pipe makes more power but the length is important as well as the jetting or pump setting.

 

[Anonymous-0]

It all depends . Most drag cars as rump was talking about exhaust port flows 60 percent of what the intake flows. Now I do not know how 2 cylinder jd heads flow but i do know that some tractor heads will flow better than 60 percent on the exhaust . header tube size length and collector length is a way to tune for torque.So if you have a head with verry little back pressure thats killing peak torque pipe size and length will make adifference that can be measured on a dyno. jmho

 

[jda50]

Thanks for all the comments. All good intresting info. The comment I read said they started with a longer straight pipe and cut it back in 1 ft sections. They noted power increased with a muffler. I guess when all said and done I like my chrome straight pipe. Since we don't spend hours in the seat it is not to loud.

 

[buickanddeere]

Only way it would loose power is if the mixture went too lean. Simple solution would be to dial the carb a wee bit.
I agree with the others.Unless it's a bored and stroked super souped machine. You will see as much "power gain" with an 30 series oval muffler. And much less noise.