This post reminds me....
few years back i had a a good customer of the kubota dealer contact me ( a few days after I quit that dealer) looking for someone to fab a tailpipe turnout on his ZD mower. I said "I bet I can do it". He brought it over, bagger and all. That's why he wanted a turnout. The original tail pipe points directly at the bagger. Being a diesel, it needed little to no restriction. The way the "hood" (aka bonnet) is shaped, the tailpipe also could not be clamped to the original, so that the hood could be raised without him having to remove it every time. Important when you're dealing with older folks, the less work the better. A turned-out/down extension would also need to run somewhat cool, as not to hurt the bag, since it was in close proximity.
On the way home from the new job (first day too) I got behind a Ford diesel pickup. I just happened to notice the tailpipes and how they are "intercooled". I remembered that the new boss actually had one of those trucks so the next day I went to his truck in the parking lot and looked at the tailpipe trying to figure it out. All it really does is speed up the air flowing through it, and draws in cooler air due to the pressure drop (as velocity increases pressure decreases). Ah-hah! Went home, made about a 110 degree turnout for the mower that bolted to the back of the hood. Then I drilled 4 holes in the extension and dinged the holes such that they actually reduced the diameter slightly while allowing air to be drawn in from outside. Drove the mower around a few minutes while the deck was on, full throttle and measured the outlet temp of the original exhaust pipe (under the hood), which was about 550 degrees F at the tip. My intercooled exhaust extension? 145 deg F. Success! Painted it up with some John Deere Muffler Black paint (the best high temp paint i've ever used) and delivered it back to the guy. He was VERY happy about it, especially the fact that he can raise the hood without having to remove the extension. Work from home again was the plan until "they" (new boss) contacted me.
The best part? The guy I work for, it's his dad. I didn't know I was gonna work for him when I started the project, I actually just quit the kubota dealer and hadn't decided what I was gonna do yet. Worked out well. Mr Charlie still to this day raves about how well that tip works.
Scrap yard. Someone mentioned that. I used to frequent the local one before they cut off all customers from being able to walk around in the yard. At the time I was building a turbocharged Ford Maverick (that nobody at the time had done) and needed some intercooler tubing. I was looking for 2 1/4" steel tubing. I wanted steel because it's cheap. What I found at the scrap yard was about 100 total feet of various straight and bent 2 1/2" aluminum thin wall tubing. PERFECT for intercooler fab. I bought all I could get, used about 6 feet of it and sold the rest on the markets. Great buy, for $6.
