Let's get the facts straight about straight pipes!

• oldoakfarmalls

When we bought the W-9 last August, it just happened to have been fitted with a straight pipe. We didn't do this to enhance performance or anything else. Don't know in the least if a straight pipe adds or detract performance. We don't pull the W-9 regularly. We haven't had it that long and are still finding out some things about it.

As far as I am concerned, noise does not equal performance. The 3" stack on the W-9 DOES attract attention--the other Clubbers know we've arrived when the W-9 is barking at everyone. That sucker is loud, but a little bit of that noise gets real old real fast IMO. Had the opportunity to do some plowing with the W-9 two weeks ago. After a couple of rounds with the plows, I pulled them out of the ground and headed for my truck to get some ear plugs. Fortunately (unfortunately?) I was called to other duty when at the truck--the Plow Days host needed some corn stalks sliced up, so I used the 460 (has a muffler) and disk for the remainder of the day.

I do not recommend prolonged operation of a W-9 with a straight pipe without hearing protection. For short periods it's OK. I am seriously considering finding the proper muffler for it.

Will it damage the engine? Probably not if the time is taken to let the engine temps normalize after hard running. A very well-respected engine/racer wonk who I work with told me that a straight pipe allows cool air to come in contact with the exhaust valves--there is less metal to heat the incoming air than there is with a muffler. With trailing throttle and when you've throttled down with load behind you, the W-9 will burp and back fire slightly. This is fresh, O2 laden air igniting minute amounts of the unburned charge at the exhaust valves he tells me.

Will a straight pipe enhance performance? Maybe. The seller of the W-9 had several other tractors at this auction, some had been modified for pulling. This seller was indeed a puller. The W-9 appeared to be untouched for pulling, but later inspection revealed the rear lugs had been cut. Other things suggest that engine performance had been enhanced by this seller. Some peeling block paint revealed odd-colored primer indicating the engine had been reworked. We used the W-9 to tow my disk home, and following my brother on the W-9, I clocked him on a slight down hill grade at 20 MPH. Maybe the governor has been diddled with. Also, the W-9 appears to be a very strong performer on our Baker Test Fan--much stronger than what you would expect from a 50 BHP tractor. So, to sum up, perhaps the straight pipe is a piece of the pie with respect to bumping up the engine's pulling performance. Again, don't know.

Get yourself a straight pipe. They do sound cool! Just don't use it for long periods--just call it your "play pipe".

Joe Evans Old Oak Farmalls

If the exhuast has any influence, you will have to re-tune the intake system to take advantage of it. If your cam, valves, carb, or air cleaner won't flow any more air, the exhaust won't matter. The main jet is adjustable, so that is a plus. Do you know anybody that has access to a dyno ? How about a disk or something that your M will barely pull in 3rd ?

Let us know what you find out.

On some motors, if you can get the length of the pipe right, it will act as a resonator and help draw more charge into the cylinder, but that could be a lot of trial and error. There is a book on tuning intakes and exhausts for best performance, it could have been by Carrol Shelby or Philip Irving. They have a formula for calculating the length of the pipe.

Good luck,
Bill

There are all kinds of guys around that operated Detroit 2 cycle diesels, and made a career of it. Some of them are now reaching old age. If anyone of them can hear anything, you need not worry about a letter series IH. If mankind was intended to listen to those Detroits, he would have been born with earmuffs. Your average teenage dance probably harder on your ears than a week of W9 ing.

1) Jetting. As you open or restrict the exhaust, you need to jet the carb, as a more open exhaust will run hotter and want a richer mixture. A closed down exhaust will run cooler, and want a leaner mixture. Run it, and watch your plugs; they will tell you what is happening.

2) An more open exhaust adversely affects low end power. Some backpressure is a good thing at low to mid rpm range. A more open exhaust is applicable for more power in the mid to high rpm range.

A longer exhaust will help scavenge the cylinders better(pull the mix through). I'm guessing you run wide open for pulling. So, you want full power there.

Thaat is the fun of tuning. Change your exhaust, check the plugs, and jet as necessary. Try it. Then adjust the pipe length, each time checking and adjusting either the plugs(hotter or colder) and jetting(rich/lean). Doing this is what makes race tuners for Nascar, dragster, sprint cars, ect some of the really valuable people on the race circuits.

Sorry, let's try that link again:

• Link