Muffler or Straight pipe

[SMTA]

I have a Farmall Smta. Overbore kit roller rockers 450lp head etc. I have been told that if I put the muffler on it that it will lug better. Has anyone tried this and does it work. I thought getting exhaust out quickly was the point.
Said something about back pressure? Thanks

 

[jd b puller]

first, look at what you define as "lug"...

Do you think it's a good thing to go to 150 feet and fall on it's knees, then plod along at full load and 1/4RPM for another 50 feet? (Hint, this is not good).

Or do you mean, "sandbagging", where you run 1/2 throttle...

 

[LEfarmallh]

Typically the farmalls don't have any trouble getting rid of exhaust. I know that some people have tried to put bigger exhaust valves in farmalls and actually lost horse power. This would make me believe that a muffler would actually be better.The only way to really know is put it on a dyno.

 

[Anonymous-0]

I had a stock 706 that at full throtle with a straight pipe would break up and sputter. Put the muffler back on and ran fine. Never seen it since

 

[Indiana Ken]

Yes - the point is to reduce back pressure for maximum HP and that typically means no muffler. However, this is only true in an ideal world where your cam is perfectly matched to your engines needs at all RPM levels. In the real world we live in your cam works best in a narrow RPM range, outside of that range sometimes a small amount of back pressure can boost cylinder pressure (torque).

I suspect this is what he/she was telling you.

 

[allaroundtractor]

I pull a farmall M that has an m@w overbore kit in it And it dynos more low end power with a muffler , But I only pull dead weight with it , where high rpms and speed is not a factor. Transfer sled straight pipe and let it rip !

 

[BG Angell]

Just use a muffler if you want to turn more rpms and not get caught. ;-)

 

[mm585]

I have heard this argument for years and from my experiance on the dyno a muffler made no diffrence at all.

 

[LarryM]

It depenbds which muffler you have. My Farmall M with a 450 engine all stock expect dome pistons will hold 67 hp at 540 but if the muffler is on it I lose 1-1.5 horsepower. The catch is that the muffler is one that has a baffle in it. If you had one that is straight through it may not make a difference.

 

[showcrop]

You can get a special pipe from Denny's. It splits into two tubes then comes back together. I saw a guy at a pull with one and asked about it. He said with a big grin that he did not believe the claim of 5 more HP put was SURE that he got three more.