Choosing an inboard engine is about more than the price tag-it is about matching the powerplant to the boat, the budget, and the work you are willing to do after the sale. These two inboard engines sit at very different points in the marine propulsion market: one is described as running great and drop-in ready, the other is a higher-priced engine with a specific part number. The price gap between them is about USD 10,000, so the choice starts with your budget and your engine-room setup.
Quick verdict
The MerCruiser is the budget-first choice at USD 4,999.00, with a running powerplant described as drop-in ready. The Yanmar is the specification-first choice at USD 15,000.00, with a clearer breakdown of the engine you are buying. Choose by budget and by what your boat was built to run.
At a glance
| MerCruiser 5.7 V8 | Yanmar 4LHA-STZP | |
|---|---|---|
| Listed price | USD 4,999.00 | USD 15,000.00 |
| Condition | Used | Used |
| Engine / output | V8 inboard | 200 hp marine diesel |
| Price indicator |
Where the MerCruiser wins
It wins on price and on clarity about what is missing. The MerCruiser sits at the low end of this pairing's five-figure spread, and the important details are spelled out: the transmission has been removed and is not included, while the bell housing is still with the engine. For someone who already has a transmission or knows how to source one, this is a realistic way to take on an inboard project without taking on the higher price in this comparison.
Where the Yanmar wins
It wins for anyone who wants a powerplant with a clear identity. The 4LHA-STZP part number removes guesswork, and the engine is labeled tested ok. If your boat is already set up for this type of inboard engine, this is the direction that gives you the least ambiguity about what you are buying.
Product notes
MerCruiser 5.7 V8
This is an inboard engine from a fresh-water environment, described as running great and drop-in ready. It uses CW RH rotation, so you know the rotation direction before you buy, and the bell housing remains with the engine. The headline limitation is the transmission: it has been removed and is not included, so you will need to arrange a gearbox before the boat can go in the water. The drop-in-ready wording makes this sound close to a ready install, but the missing transmission is a genuine part of the project. If you already have a transmission or are buying this as a solid starting point for a build, the lower price and the runnable condition make it an attractive starting point.
Yanmar 4LHA-STZP
This is a 4-stroke marine diesel rated at 200 hp, and the 4LHA-STZP part number leaves little doubt about what you are buying. It was built in Japan, and the engine is labeled tested ok. The trade-off is the absence of a warranty, which puts the burden of verifying condition on you before installation. The power rating and part number make it easier to check whether this diesel fits your boat, and the marine diesel classification means it belongs in an inboard application. If you are committed to diesel power and want a specification you can work from, this Yanmar gives you a concrete starting point-at a price that matches its more specific identity.
Final choice by use case
Choose the MerCruiser if your budget is the main constraint and you are prepared for an incomplete powertrain. Choose the Yanmar if you are ready to spend at the upper end of this comparison and want the engine with the clearer specification. Both are used engines, so the final decision should also include a thorough inspection before anything goes into your boat.
