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Ever hear of a seven cylinder motor???

J

JD Seller

Well-known Member
I was watching a video about combines. The MF 9540 combine was being featured. It has an inline seven cylinder Sisu motor. I just found this as being odd. I know that Kubota has some five cylinder inline motors but the seven I had not heard of.
 
Agco Sisu Diesel engine for off road use.
a257550.jpg
 
Mercedes used a 5 cyl. 3 Lit. diesel engine in autos in the early '80s. I have one sitting in the driveway. The worst thing they did was use a Harrison compressor for the Air Conditioner. I believe a Jap replacement would be better.
 
AGCO Power (aka Sisu Diesel) only has two piston diameters and two stroke lengths in their entire engine line-up. When the combines needed more power than what their largest 6-cyl would provide they just added another cylinder to make seven. This fit into their current manufacturing system easier and less costly than what re-tooling for a larger piston would take. They also now manufacture a V-12 engine for the same reason.
 
Sounds like how Detroit Diesel used to do it.

Successful radial airplane engines had odd numbers of cylinders to avoid having two cylinders firing right next to each other, so the engine would run smoothly. 1-3-5-7-2-4-6 would be the firing order on a 7 cylinder. Note how it would fire every other cylinder, and end up back at 1.

I wonder if the Sisu engine has the same firing order. Seems counterproductive to take a dynamically balanced inline 6 and screw it up like that though...
 
I would think there is a little more head scratching involved in designing an engine with an uneven number of cylinders. Firing degrees and the resulting torsional vibration changes has to be dealt with differently. The five cylinder in my Colorado is more buzzy than I expected to see from an uneven numbered cylinder engine.
 
The one thing (other than long life) the five cylinder KUBOTA would do is take a loaded farm wagon pull out on the road and pick up from nothing in 5th gear. Other words a lot of low end torque. It was always explained to me that there was a power stroke ever 60 degrees so always pushing the crank. Sure never had any problems with that engine. I don,t know about the seven cylinder guess they have it figured out
 
We have that same engine (agco power/sisu in-line 7) in a Terragator 9300b. Runs very smooth, has the same power as the C13 powered terragators, and about half as loud. Seems to be a much shorter block than the cat. They did have a recall last year. Came and replaced the whole long block on agco’s dime. Shipped new motors in and shipped the recalled motors back overseas. They were recalled due to a design problem that caused oil consumption. I know the dealer mechanic had a couple combine motors to replace after he worked on our Terragator.
 
" It was always explained to me that there was a power stroke ever 60 degrees so always pushing the crank."

INTERESTING!

A 4 cycle engine fires all it's cylinders over two turns, 720? of crankshaft rotation, 720? divided by 5 cylinders = a power stroke starting every 144?.

Doesn't quite seem to work out to "a power stroke every 60 degrees!

Seven cylinder would be 720? divided by 7 cylinders = a power stroke starting every 102.9?.
 
Interesting the reason for the variance being the 6 cyl engine is inherently self balanced. Mercedes Benz has a 5 cylinder diesel in it's sedans I read.
 
Volvo built in-line 5 cylinder 2.4 & turbo-charged 2.5 engines in the early 2000's, I have the turbo-intercooled 2.5L in my 2006 S40. Much smoother than an in-line 4 but not as smooth as an in-line 6.

An in-line 7 is not common but a radial 7 is very common.
 
. A five cylinder engine has the size and economy of a six with the power, noise and vibration of a four .
The inline six is one of the better compromises of size, being compact , low cost , simplicity, strength, inherent balance and power.
 
Also Olds, Pontiac, Chrysler, Packard. I am sure others but don't feel like looking thru my books right now. I have the big shop manuals for all the cars from the 40's & 50's.
 
I remember back in late 60s or maybe early 70s when ford came out with the 3 cylinder diesel engine in some of their small diesel farm tractors.
 
I think it was in the mid 80's I bought an 18 hp AC 3 cyl diesel that I had hooked to a 3 pt, 3 blade turf mower I used to mow the place. Nice mower combo but cutting around the trees required you to be paying attention. Never had a minute's trouble out of the little sucker and it ran stout, low vibes.
 
B&D - I disagree! A 5 cylinder is almost as smooth as a 6,and as powerful given equal displacement,and
MUCH smoother than a 4, quieter too.

I've put 150,000 miles on an in-line 5 Volvo engine. The 2.5L in-line 5 makes 218 hp, roughly same hp as
the 5.0L HO Mustang engine on half the displacement, torque was down a little from the 5.0L. But with
variable valve timing on intake & exh. it had a flat torque curve from 1750 rpm to over 4000 rpm.

I know GM built an in-line 5, That was pre-Bailout when they couldn't afford 6 pistons per engine.
 
How's about a 1-cylinder tractor? Don't know about the newer models, but my old Pasquali 986 had a 21hp, 1 cylinder diesel built by Lombardini.
 
I had heard of this Sisu engine before. Keeps it simple for them. They only have 2 pistons sizes, just add another cylinder for more power. Crazier is that this 7 cylinder uses 2 cylinder heads. A head off a 4 cylinder, and one off a 3 cylinder. They really do keep it simple.
 
Modern View won't let me edit, so edit to say that Sisu actually has 3 piston sizes. One for the 3.3L, 4.4L, and 6.6L engines. One for the 4.9L and 7.4L engines, and one for the 8.4 and 9.8L engines.
 
The 3.3, 4.4/6.6, and 4.9/7.4 engines all have the same 108mm bore - it is just the stroke that is different for the two sizes of the 4- and 6-cyl engines in this family. The larger bore is used for the 8.4, 9.8, and 16.8 family of engines.
 
(quoted from post at 11:17:15 02/19/18) B&D - I disagree! A 5 cylinder is almost as smooth as a 6,and as powerful given equal displacement,and
MUCH smoother than a 4, quieter too.

I've put 150,000 miles on an in-line 5 Volvo engine. The 2.5L in-line 5 makes 218 hp, roughly same hp as
the 5.0L HO Mustang engine on half the displacement, torque was down a little from the 5.0L. But with
variable valve timing on intake & exh. it had a flat torque curve from 1750 rpm to over 4000 rpm.

I know GM built an in-line 5, That was pre-Bailout when they couldn't afford 6 pistons per engine.
Click to expand...
Don’t get overly offended . It was more of a joke about 5 cylinder engines .
 
> I disagree! A 5 cylinder is almost as smooth as a 6,and as powerful given equal displacement,and
MUCH smoother than a 4, quieter too.

An inline six is inherently balanced, as the crank throws are 120 degrees apart. A three cylinder inline is also balanced for the same reason.

GM developed the inline five to solve a specific problem: The Isuzu-designed GMT355 truck didn't have room under the hood for either an inline six or a V-6. And a bigger engine than the four-banger was needed for the US market. A friend of mine worked on the project, and he said they had a lot of vibration problems. I think they had to add a second balance shaft to get the vibration under control.
 
SISU, VERY FAMOUS OLD ENG BUILDER, AIRCRAFT ENGINES W.W.II...EICHER TRACTORS GOT EM...BE BLESSED, GRATEFUL, PREPARED...
 
THE POOR OLD AIR FARCE HAD TO USE THE WRIGHT/STUDEBAKER 7 CYL 1300 IN THEIR T-28A, WHILE THE REAL PILOT, NAVY, GOT THE 9 CYL WRIGHT 1820...ONE MORE PROP BLADE, TOO...EAT YORE HEART OUT
 
Above, on page one, Crazy Horse's reply to Ultradog's post - This is a good book -, is a history of the USS Silversides, USS 236. In the history is reference to the sub's seven cylinder auxiliary engine.
 
I think Agco uses Sisu in everything except the Fendt which has a Mann in them. I would guess the 16.8 in the MT800 Challenger series is a Sisu also.

I have turbo 5 cylinder in our 1992 kraut wagon. It is better than the first 4 banger we had, you didn't dare try to pass with the ac on. But I will take my 2010 Sienna any day.
 
On the radial I don't think balance has anything to do with it as compared to a crankshaft drive I engine due to the layout of the engine. I think it's what'll fit and if you need more just add another bank or two. I think 9 per row was the max they used.
 
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