Yanmar 2V78 re-introduction..

[Stuart]

The Yanmar 2V78 engine has been talked about quite a bit here so I thought I'd post up the text below. Incase anyone didn't know it seems it has been re-vamped and now comes in Horizonal flavour as well as Vertical. No more messing with those oil feeds...
(This engine is fitted to the Yanfield owned by Wolfgang)
PDF Manual download from here: http://tinyurl.com/2csprk

Returning with a vengeance: Yanmar reintroduces vertical shaft V-twin to North American markets; horizontal shaft to follow, both assembled in Georgia Diesel Progress North American Edition, June, 2005 by Mike Brezonick.
It is not uncommon for products to occasionally be "reintroduced" to a market. In some

cases, such reintroductions are cosmetic, little more than marketing "do-overs," with

nothing really changed from the initial debut.

But when Yanmar America Corp. recently announced the reintroduction of its V-twin

diesel to the North American markets, it quickly became obvious that more than just the

name had changed.

In fact, while some things have remained essentially unchanged since the 2V78 diesel

was introduced in mid-1997--the bore and stroke remain the same, as does the

displacement and the 80[degrees] vee configuration--this latest generation of the

product is, in many ways, a whole new animal.

It's therefore not surprising that the nomenclature has changed, with the new model

carrying the designations 2V750V (vertical shaft) and 2V750H (horizontal shaft).

"We first introduced the 2V78 in the 1990s and we have OEMs that continue to use that

engine," said Jeff Williams, manager, sales and marketing at Yanmar America, Buffalo

Grove, Ill. "It's alive and well.

"Because of some issues perceived by the market, primarily noise-related issues--and

not so much noise as noise quality--we decided not to expand that offering. We

maintained the existing customers, but we pulled in, cancelled new programs and

announced we were going to discontinue the product.

But over the last few years we were able to have some of our people in Japan take a

second look at the product line in terms of refining it and keeping it alive. We were

able to make some changes that really addressed some of those issues and now as the

name says, back with a vengeance."

The 2V750 engine is a two-cylinder, liquid-cooled overhead valve V-twin diesel rated

18.6 net intermittent hp at 3600 rpm. It has an overall displacement of 0.749 L on bore

x stroke dimensions of 78 x 78.4 mm.

The naturally aspirated engine incorporates two valves per cylinder, along with an

indirect-injection system and proprietary combustion chamber design derived from the

company's well-known TNV series diesels.

That core engine technology is one of the two most significant changes from the

previous version, with the other being a newly designed cast-iron cylinder head. The

earlier engine incorporated an all-aluminum block and head, which is where some of the

noise quality issues came from, Williams said.

"Because we tried to pattern the engine as much as we could on the gasoline equivalents

in terms of the envelope size, the weight and everything else, we went with an aluminum

design," Williams noted. "The negative of that came down to two things. One was

vibration, which we now have overcome with an isolation system that has worked out and

proven itself very well, so that became a non-issue.

"The other was noise quality. It wasn't so much a matter of decibels, it was more a

perception of noise quality. When the engine was cold and you first started it up, it

had a definite diesel detonation noise that a lot of our OEMs found objectionable.

"We went back and determined that by going to a cast-iron head and incorporating the

IDI combustion system design of our new TNV 1 series, we found all kinds of good

results. We've addressed the noise quality issue dramatically, decreased exhaust

temperatures, decreased heat rejection and have dramatically reduced emissions (the

engine is EPA Tier 2 complaint, the company said). So we were able to really improve

the engine to the point where we've got a lot of confidence going forward."

Rated noise emissions of the 2V750 engine at load is 90 dB(A) at 1 m, according to

Yanmar.

The engine incorporates a 12 V electric starter, 20 amp alternator and electric engine

stop solenoid. A glow-plug system aids in cold starting and the glow plug is positioned

between the cylinders for compactness.

Engine cooling is through a top-mounted radiator with suction fan and a full pressure

lube system incorporates a gear-driven trochoid pump. Options include an engine

silencer and cover and dry-type air cleaner with paper element filter.

Dimensions for the 2V750 base engine are 20.51 in. long, 15.70 in. wide and 16 in.

high, which is very similar to the earlier engine, which was 20 in. long, 15.58 in.

wide and 17.58 in. high. Dry weight is also close, 122 lb. for the base 2V750 engine

versus 115 lb. for its predecessor.

Back in 1997, a big target for the diesel V-twin was commercial tuff and lawn and

garden equipment--particularly zero-turn radius mowers--which remains the primary

application for the vertical shaft engine, Williams said. The horizontal shaft engines

will have applications over a broader spectrum of products, including pumps,

compressors, welders, gen-sets and small mobile equipment.

"One of the things that's nice now versus the first time around is that as gasoline

engine manufacturers have increased their output, more and more of the ZTR mower

manufacturers have gone to a vertical shaft design for most of their lineup," he said.

"A horizontal shaft diesel is kind of hard to fit in a lot of those machines, it's more expensive to produce and so not as attractive.

http://tinyurl.com/ypulmf to see the V shaft