How large of an engine, or motor, do I need to drive a ZENA welding system?

If you will be using a 4 cycle GASOLINE engine -- using pulleys and a V or SerpentineBelt to drive the power generator (a common configuration for stand alone welders), an:

• 11 hp, or larger, engine will drive a 150 Amp model, a
• 16 hp, or larger, engine will drive a 200 Amp model, and a
• 22 hp, or larger, engine will drive a 250 Amp model.

If you will be using a 4 cycle water cooled DIESEL engine -- using pulleys and a V or SerpentineBelt to drive the power generator (also a very common configuration for stand alone welders), a:

• 6 hp, or larger, engine will drive a 150 Amp model, a
• 10 hp, or larger, engine will drive a 200 Amp model, and a
• 14 hp, or larger, engine will drive a 250 Amp model.

  NOTE: Add 2 hp for air cooled diesels

If you plan to use a special design HIGH SPEED ENGINE (typicality a 2 cycle gas, diesel, or turbine) to directly drive the power generator:

• an engine capable of producing a minimum of 7.5 hp at 7,000 rpm is required to directly drive a 150 Amp ZENA power generator, and
• an engine producing a minimum of 10 hp at 7,000 rpm is needed to directly drive one of our 200 Amp models, and
• an engine producing a minimum 13 hp at 7,000 rpm will directly drive one of our 250 Amp power generators.

If you will be using an ELECTRIC MOTOR -- using pulleys and a V or SerpentineBelt to drive the power generator, a:

• 7.5 hp 3450 rpm motor, or larger, will drive a 150 Amp model, a
• 10 hp 3450 rpm motor, or larger, will drive a 200 Amp model, and a
• 12.5 hp 3450 rpm motor, or larger, will drive a 250 Amp model.

  Note: It's possible to use two 5 hp 3450 rpm motors (typically, with each on it's own, separate electrical circuit) -- belted together to drive a 150 Amp welding system.

A couple of examples:

• Example 1 -- electric drive motor -- Our 150A welders can be driven to maximum (or near maximum) output power by an 3,450 rpm continuous duty 5 hp electric motor for a short period of time. BUT, as welding power is produced for an extended period, a 5 hp electric motor heats up and looses power. Therefore, a continuous duty 7-1/2 hp electric motor is the practical minimum needed for 100% duty use. (In this case, we are assuming that the engine is equipped with a 6" drive pulley and that the power generator is equipped with a 3" shaft pulley -- a 2:1 pulley ratio.) CLICK HERE for more on electric drive welding systems for in shop use.

• Example 2 -- internal combustion engine -- A typical 11 HP, electric start, gasoline fueled, 4-cycle engine (horizontal or vertical shaft) which produces its rated maximum horsepower at approximately 3,500 rpm, can be used to drive our 150A power generator -- IF the engine is equipped with a heavy enough flywheel to insure the engine's ability to operate smoothly without loss of rpm under maximum load. (In this case, we are assuming that the engine is equipped with a 6.75" drive pulley, and that the power generator is equipped with a 3.2" shaft pulley -- a 2.1:1 pulley drive ratio.)

NOTE: In some cases, when using single cylinder internal combustion engines, we find that extra horsepower is required to insure proper operation due to inadequate engine flywheel mass. Generally, our customers report that 14-20 HP single cylinder gasoline engines (which are usually factory equipped with electric start and with built-in alternators) of the type often found on riding mowers generally make good welder drive engines. Kohler and Onan engines reportedly do particularly well, since they are frequently factory equipped with heavier flywheels. And, we have had many customers report that Honda's electric start 11 HP (and larger) engines make very good power sources for 150A welders.

Twin cylinder gas engines ranging from 16 to 20 HP have been used successfully drive 150A power generators without needing modification to the stock flywheel configuration.

Small, 6+ HP diesel engines also make excellent power sources for 150A welders.

More information -- application notes:

Feel free to call (or e-Mail) us for specific information and/or recommendations -- or, if you have questions about a specific application that you have in mind.

APPLICATION NOTE 1 -- small four cycle engines:
Remember, when working with lower hp 4 cycle engines, flywheel mass must always be great enough to insure smooth operation under maximum load.

APPLICATION NOTE 2 -- riding mowers:
Customers report that there are many very inexpensive used riding mowers on the market which have worn out mowing equipment, but which have perfectly good engines -- and often good transmissions as well.
They also tell us that a "riding welder" is an extraordinarily useful configuration. We agree, and often use this type of welder for marketing presentations and trade show expositions -- as well as for general maintenance work.
We do not have formal plans for this type of installation. However, we do have pictures and descriptions of such installations on our web site:

Links to photos and notes on a few typical small engine retrofits:

CLICK HERE for
pictures of a 150A riding welder

CLICK HERE for
pictures of a free standing 150A engine driven welder made using parts from an old 11 HP riding mower

CLICK HERE for
pictures of a worn out engine driven welder retrofitted/repaired with a 200A ZENA welder

ZENA™ is a trademark owned by ZENA, Inc. for its welding systems and related products.

US & Foreign Patents Pending

© Copyright 1998-2004 by ZENA, Incorporated. All rights reserved.

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