I went to a truck show that was at the American Truck Historical Society's covention in Colorado Springs yesterday. There were a lot of heavy duty trucks, medium duty and pickups there. My daughter took 275 pictures.

A sound celebrated here was the bark of a Cummins NHS-275. This early '50s model, nicknamed "Two Six Bits," has a gear-driven supercharger and a unique camshaft. The cam's lobes have an almost flat profile that causes the valves to pop open, stay wide open, then pop shut. It makes noise like no other diesel. He told me that some of the unique sound was from the split exhaust manifold as well. It also has a 4 valve head and top RPM is 2100.

Because of this, Ken Talley of Madeira, Calif., has a Two Six Bits mounted in a special trailer. The engine's tied to a Telma retarder from a school bus that acts as a dyno, so it can work like it did while climbing long grades in the days before the interstates. He fired up the 275 , let it warm, then loaded it and made it howl through its straight-through stack. A turbocharger would muffle that, and I was told there would be short flame that glows at the tip of the stack when it was dark enough out. Several trucks at the show had that engine.







He also had this one converted to propane but I didn't get a chance to hear it run.



We saw several Dodges heavy, medium and pickups. This was one of my favorites. I would love to have one of them.

 

Very cool. At some of the tractor and thrashing shows i go to in the fall, i see some 2 stroke super charged diesels they have a different sound to them with a straight pipe. They came in oliver super 99's and a cockshutt and oliver model 1950.

 

Longer ago than I care to think about, I used to drive a '54 KW with twin sticks (5 and a 3) and a "two-six-bits". They do have a very unique (read: noisy ) sound. Did they have Jakes on them? Wait until you hear that bark. There is an outfit that comes to the Brooks, OR truck show nearly every summer and they have a couple of Macks with those in them. They fire them up several times during the day, hit the revs and let them come back on the Jakes. COOL!

The 275 I drove was pretty worn out so it didn't really have the power it should have had and on very much of a pull the oil light would start flickering. Never did blow up though. Wish I had that rig myself now.

 

The fellow I talked to, Ken, said that the reason he set the engine up that way was when you used the Jake brake like that it put a lot of strain on the supercharger shaft. So this was the way he came up with to get the sound and not damage the engine. I wish I could have gotten a recording of the sound on my cell phone, but when he started it up we were a ways away, and we hurried to get there before he shut it back down as it was something I'd never quite heard before. He told me about a fellow that made a video on how to shift a twin stick truck. At the end of the video, they had a truck with a 275 pulling up a long hill toward the camera. I'm going to try to locate the video, it sounds neat.

 

They are also called gear grinders because the supercharger is gear driven. If you were standing near while it idles the supercharger has a rather unique sound also. Cummins also built a 300 horse model that had lower compression but I haven't seen very many of those. I liked driving that rig pretty well. Not sure how well I would like it now after being spoiled with the all the air ride and quiet cabs we have now.

 

Yep that would be a 4-53 Detroit diesel... We have a tractor puller around here that wicked one up an pulls hobby (hot class) with it. I have a friend who just picked up a '74 4x4 Chev K20 with a 4-53 and an Eaton five speed swapped in it. Kinda can't wait to get that ol' girl lit.

 

Yeah, we got one of those old beaters here at work for a back up fire pump. The coupling between the gear drive and the supercharger broke a few years ago and no one in the country had another one. Had to have a local machine shop fab one up and that was a mess. It's very dependable but there getting harder and harder to find parts for.

GM also made a 3-53 they put in some of the older tractors. Talk about a bark now, pheww.
And, John Deere made what was a 2-53 I believe and used it in there 435 series tractors.

 

3-71 4-71 6-71(238) 8-71 12-71 16-71 6v-92 8v-92 12v-92 16v-92 and so on. All two cycle that had to have a roots blower to run. If the shaft broke and the engine was not connected in gear, the engine would wind up till it broke. Usually turning the shaft around would temporarly fix it.

I never associated much with the 53 series, there were a bunch of them. A 12v92 is over 650 hp. They could be mounted in a long nose, saw a few of them, they are two 6v engine bolted together at the front of the engine, crank and all. Put well over a million miles on a CO4070 with 238. Still have a 4-71 blower at the house.

Nothing has the sound of dual 12v71 pipes behind the cab pulling a mountain. Nothing except the sound of the pump meter while filling it with fuel, 2 1/2 mpg working it hard.

 

Our trenching company has an old Speicher 7060 trencher that is powered by a 4-71, and has a backfilling machine powered by a 3-53, the 4-71 sounds pretty cool, but yo have to where head phones to run the backfiller, the old 3-53, will flat out scream. Full throttle all day long.

 

If anyone cares heres a picture of a nice model 1950 cockshutt with a supercharged 2 stroke GM diesel (not mine i wish)

 

Lets see now, a 3-53 winds to about 3500 rpm, it is two cycle so it fires the same number of times as a four cycle running 7000. Herd of bumblebees is what they were called.

 

I've heard em called that, and heard em called screamers. In the backfiller we're running around 3350 all day, because of it being loaded down. The harder you run the old Detroits the more they like it. At idle it sounds like a Cummins at over 2000 RPM

 

Yep, heard that before too.
Here's a link to the John Deere 435 with the 2-53 Detroit. Pretty cool.

http://www.petcaretips.net/john-deere-435.html

And the 830 is on there too. I want one of those. 472 cubic inch two cylinder.