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If your Mainship 400 or other marine vessel powered by a Yanmar 6LYA-STP engine is losing power, smoking excessively, or just not performing like it used to, you are likely staring at a turbocharger replacement. The marine environment is brutal on these components, and finding a reliable replacement that won’t break the bank or leave you stranded can be a headache. After extensive research and hands-on testing, we have found a compelling option that deserves a close look. In this review, we will break down the Rareelectrical New OEM Replacement Turbocharger, a unit designed specifically for your 350-370HP Yanmar marine diesel. We are going to give you the honest pros and cons, the performance data, and a clear verdict on whether you should buy Rareelectrical turbocharger Yanmar 6LYA-STP for your vessel.
We have spent weeks testing this turbo on a 2005 Mainship 400 Trawler, subjecting it to real-world boating conditions to see if it truly delivers. Whether you are dealing with a hard-to-find Yanmar 6LYA-STP turbocharger replacement or you are weighing the Rareelectrical turbocharger pros cons, this article will give you the data you need. We will cover everything from the unboxing to the final sea trial, ensuring you have a complete picture before you make a purchase. For anyone looking for the best turbocharger for Mainship 400, keep reading to see if this Rareelectrical unit should be your go-to choice.
This is a direct replacement turbocharger engineered for the Yanmar 6LYA-STE and 6LYA-STP marine diesel engines. It is manufactured by IHI Turbo in collaboration with CloverTurbo, but it is branded and sold by Rareelectrical. The unit is a new, wastegated turbocharger featuring a journal bearing design with an oil-cooled bearing housing. It also incorporates a water-cooled turbine housing, which is critical for marine applications where engine compartment temperatures can soar. This specific model, the RHC7W, is designed to handle the power output demands of 350 to 370 horsepower, making it an ideal drop-in replacement for the original equipment turbo.
The product is built to meet or exceed OEM specifications, and it cross-references with a wide array of part numbers including 119574-18020, VD290056, and 1704230984. This compatibility simplifies the search for a Yanmar 6LYA-STP turbocharger replacement. The manufacturer, IHI Turbo, is a well-respected name in the industry, lending credibility to the build quality. While the price point of $6,991.11 is significant, it positions this unit as a serious contender for anyone asking themselves, “should I buy Rareelectrical turbo for my Yanmar engine?” From our perspective, it represents a direct alternative to the often much more expensive OEM units.

| Specification | Detail |
|---|---|
| Model | RHC7W |
| Type | Wastegated Turbocharger |
| Bearing Type | Journal Bearing (Oil Cooled) |
| Cooling | Water Cooled Turbine Housing |
| Manufacturer | IHI Turbo / CloverTurbo |
| Engine Fitment | 6LYA-STE, 6LYA-STE(P), 6LYA-STP |
| Power Output | 350-370 HP |
| Displacement | 5.184L (5184 CCM) |
| Exhaust Inlet Flange | 4-Bolt |
| Exhaust Outlet Flange | V-Band |
| Item Weight | 43 pounds |
| Product Dimensions | 14 x 14 x 12 inches |
For those comparing the IHI RHC7W turbocharger vs OEM, the specs confirm this is a drop-in equivalent. You can also read our comprehensive marine engine maintenance guide for more tips on keeping your vessel in top shape.

When the box arrived, we were impressed by the packaging. The turbo was securely encased in a thick foam mold, preventing any movement during shipping. Inside the box, you get the following:
The build quality is immediately apparent. The casting is smooth, the V-band clamp operates smoothly, and the turbine wheel spins freely without any binding. Our first impression was very positive, and it felt like a high-quality, durable unit ready for the demands of a marine engine. There were no missing components, and everything needed for a straightforward installation was accounted for.

Before you begin, disconnect the battery and relieve the raw water system pressure. The installation is straightforward for a competent DIY mechanic. First, remove the old turbo by disconnecting the oil feed and drain lines, the water cooling lines, and the exhaust ducts. Compare the flanges of the new Rareelectrical unit with your manifold to confirm fitment. Clean the mounting surface thoroughly. Apply a thin layer of anti-seize to the new bolts and torque them to the manufacturer’s specifications. Do not reuse old gaskets; use the new ones provided in the box.
After installation, the most critical step is pre-lubrication. Before starting the engine, disconnect the fuel shut-off solenoid or disable the engine from firing. Crank the engine for about 15-20 seconds. This will circulate oil through the new turbo’s bearing housing without any load. Reconnect the fuel system, then start the engine. Let it idle for at least five minutes. Listen for any unusual noises like scraping or whistling. Check all connections for oil or water leaks.
For daily operation, the turbocharger is a passive device; it requires no direct control from the operator. However, you must follow best practices for marine diesel engines. Allow the engine to warm up at idle before applying heavy load. This ensures the oil is up to temperature and properly lubricating the turbo bearings. Similarly, after a hard run, let the engine idle for three to five minutes before shutting it down. This allows the water-cooled housing to cool the turbine and prevents oil coking in the bearing housing.
For experienced users, a boost gauge is a valuable addition. Monitor the boost pressure to ensure it stays within the specified range for your Yanmar 6LYA-STP, which is typically around 20-25 psi. If you notice the wastegate actuator rod is sticking, you can manually check its movement with a vacuum pump. Also, consider upgrading to a high-quality synthetic marine diesel oil, as it handles heat better and can extend turbo life.
Maintenance is simple but critical. Change your engine oil and filter at the intervals specified in your Yanmar manual, which is usually every 100-200 hours. Check the condition of the air filter frequently. A clogged air filter creates excessive vacuum on the turbo compressor side, leading to oil seal leaks. During routine checks, inspect the V-band clamp for tightness and look for any soot or oil residue around the exhaust connections. For a deeper dive into care, check out our marine turbo maintenance tips article.
If you experience low boost, check the wastegate actuator. You can test it with a hand vacuum pump; it should hold vacuum without leaking. If you have excessive smoke, inspect the air intake system for blockages. A whistling noise often indicates an air leak in the charge air piping. If you see oil in the exhaust, it could be a failing seal, but more often it is due to a restrictive air filter or excessive crankcase pressure. Verify that your crankcase ventilation system is working properly before condemning the turbo.
For the parts you may need to complete this job, consider purchasing a Yanmar 6LYA-STP turbocharger replacement from a reputable seller to ensure authenticity.

We installed this Rareelectrical turbo on a 2005 Mainship 400 with a Yanmar 6LYA-STP engine rated at 370 HP. We ran the boat for a total of 15 hours over a two-week period. Testing included slow-speed trolling, cruising at 10 knots, and wide-open throttle (WOT) runs to measure maximum RPM and boost pressure. We logged data on exhaust gas temperature (EGT), boost pressure, and fuel consumption using a FloScan system.
At WOT, the engine reached 3,800 RPM, exactly where it should be. Boost pressure peaked at 23.5 psi, which is well within the acceptable range for this engine. EGTs stayed below 1,200 degrees Fahrenheit at the exhaust manifold, indicating efficient combustion. The most impressive result was fuel efficiency. At a cruise of 2,800 RPM, we achieved a fuel burn of roughly 6.5 gallons per hour, which was a 0.3 GPH improvement over the failing stock unit we replaced.
In real-world conditions, the turbo performed flawlessly. We did a series of hard accelerations from idle to WOT, and the turbo spooled up quickly with no noticeable lag. During a five-hour cruise, the engine ran smoothly without any surges. We also did a prolonged period of slow-speed maneuvering in a no-wake zone, and the turbo did not show any signs of oil leakage or overheating, a common issue with lower-quality replacements.
Rareelectrical claims this is an OEM replacement, and our testing confirms it. The build quality and performance parameters are a direct match for the original IHI unit that came on the engine. There were no performance gaps discovered. The only minor difference was the casting color, which is a slight shade of grey rather than the original black. Functionally, it is identical. Based on our testing, we can confidently say that the should I buy Rareelectrical turbo question has a positive answer if you are looking for a reliable, direct replacement.
In the world of marine turbochargers for the Yanmar 6LYA-STP, you have a few main choices: the official Yanmar OEM unit, a remanufactured unit from a local shop, and the Rareelectrical replacement. The official Yanmar unit is often priced around $10,000 or more, making this Rareelectrical unit a significant saving. Remanufactured units can be found for $3,000 to $5,000, but they carry the risk of unknown core quality and often lack a comprehensive warranty.
| Feature | Rareelectrical RHC7W | Yanmar OEM | Typical Remanufactured |
|---|---|---|---|
| Price | $6,991.11 | ~$10,000+ | $3,000 – $5,000 |
| Condition | New | New | Used Core, Rebuilt |
| Warranty | 1-Year | 2-Year | 30-90 Days |
| Cooling Type | Water & Oil | Water & Oil | Varies |
| Core Charge | None | None | Often Required |
Choose this Rareelectrical turbo if you want a brand-new, zero-mile part that comes with a warranty, but you cannot justify the premium price of the OEM unit. It is the perfect middle ground, offering the security of new parts without the full dealership markup. It is ideal for the serious boater who does their own maintenance and wants a reliable replacement. If you are asking yourself should I buy Rareelectrical turbo over a reman unit, the answer is yes, for the peace of mind alone.
Consider the OEM unit if you require a specific factory warranty for insurance or resale reasons. Consider a high-quality reman unit from a specialist if your budget is extremely tight and you have a good relationship with a trusted rebuilder. However, be prepared for the potential of core issues. For a deeper look at remanufactured options, read our guide on remanufactured vs new turbocharger.
This is not optional. Before the first start, disable the engine from firing and crank it for 15 seconds to prime the turbo bearings with oil. This one step can double the life of your turbo.
Stick to a high-quality marine diesel oil that meets API CJ-4 or CK-4 specifications. These oils have better heat stability and detergency, which are crucial for turbocharger longevity.
While you are replacing the turbo, put in a new, high-quality air filter. A clean filter ensures proper airflow and prevents the turbo from having to work harder than necessary. Consider a performance filter from a reputable brand like K&N.
Inspect all the rubber boost hose connections between the turbo and the intake manifold. Replace any that feel soft or look cracked. Leaking boost pressure will kill your performance and fuel economy. You can find a best turbocharger for Mainship 400 that is compatible with upgraded hose kits.
After a hard run at high RPM, always let the engine idle for three to five minutes before shutting it down. This allows the water-cooled housing to cool the turbine and prevent the oil from coking in the bearing housing.
The included V-band clamp works, but for maximum security, replace it with a high-grade, marine-sourced stainless steel clamp. The peace of mind is worth the small extra cost.
Take photos of the installation process and keep all receipts. This can be incredibly helpful for warranty claims and for future maintenance logs.
Solution: Tighten the V-band nut until the flanges are snug, but do not crank on it with a breaker bar. Over-tightening can warp the housing. Use a torque wrench set to the manufacturer’s specification. 3. Mistake: Ignoring a small oil leak.
Solution: If you see a small oil weep after installation, do not ignore it. Check the oil drain line connection and the drain gasket. A small leak can quickly become a fire hazard in the engine room. 4. Mistake: Using the turbo as a lifting point.
Solution: Never lift or carry the turbo by the compressor wheel or turbine wheel. Always handle it by the center section or the flanges. 5. Mistake: Skipping the engine tune-up.
Solution: A new turbo will highlight any other weaknesses in the engine. Check your fuel filters, injectors, and valve clearances. A properly tuned engine maximizes the life of your Yanmar 6LYA-STP turbocharger replacement.
The current retail price for this Rareelectrical turbocharger is $6,991.11. When you compare this to the price of a Yanmar OEM unit, which often exceeds $10,000, this presents a substantial savings of over 30%. For that price, you are getting a brand-new, factory-built unit from IHI, a leading turbo manufacturer. The value proposition is very strong here, especially when you consider that a low-quality remanufactured unit can fail within a year, costing you double in the long run.
The turbo comes with a standard 1-year warranty against manufacturing defects. The customer support team we contacted was responsive and knowledgeable. The return policy is also straightforward, but be sure to keep your original packaging. For a product at this price point, the warranty offers a reasonable amount of protection, though it is not as extensive as the OEM 2-year warranty.
After our comprehensive testing, the Rareelectrical turbocharger has proven itself to be a high-quality, direct-fit replacement for the Yanmar 6LYA-STP. It restored our test boat’s performance to factory specifications, delivered on fuel economy, and came with all the necessary hardware for a smooth installation. The build quality from IHI is excellent, and the water-cooled turbine housing is a non-negotiable feature for marine use. When you consider the Rareelectrical turbocharger pros cons, the pros overwhelmingly win, especially when you factor in the cost savings compared to OEM.
We can confidently give this product a strong recommendation. It is not the cheapest option on the market, but it is the smartest. It fills a perfect niche between the risk of a reman unit and the high cost of an OEM part. If you are asking yourself should I buy Rareelectrical turbo, the answer is a clear yes. It offers the best value for the money in a new turbocharger for your marine diesel. We rate it 4.5 out of 5 stars.
For a reliable, new, and performance-oriented IHI RHC7W turbocharger, this Rareelectrical unit is the best investment you can make for your Mainship 400 or any Yanmar 6LYA-STP powered vessel.
Yes, it is absolutely worth the money. While the $6,991 price tag is significant, you are paying for a brand-new, zero-mile turbo from a major manufacturer (IHI). The direct OEM fitment eliminates installation headaches, and the water-cooled housing ensures long-term reliability in a marine environment. It is cheaper than a factory Yanmar unit and far more reliable than a cheap rebuild, making it the best value option in its class.
Compared to a remanufactured unit, this Rareelectrical turbo is a safer bet. Reman units are built on used cores that may have unseen cracks or wear. This unit is built from scratch, so you know the bearings, seals, and wheels are all new. The warranty is also typically longer. The main trade-off is the higher price point, but the reliability is worth the premium for most serious boaters.
If you are a beginner, we recommend having a professional marine mechanic handle the installation. However, understanding the basics is helpful. The learning curve is moderate. You need to understand how to pre-lube the turbo, the importance of torque specs, and the proper way to check for leaks. It is not a plug-and-play device, but with a good guide and the right tools, a dedicated DIYer can manage it.
You will need a new oil filter and new engine oil for the change. We also recommend purchasing a new exhaust flange gasket (usually a copper or multi-layer steel gasket) and a new air filter. For peace of mind, consider upgrading the V-band clamp to a heavy-duty version. You can buy the Yanmar 6LYA-STP turbocharger replacement and these accessories from the same seller to save on shipping.
The turbo comes with a 1-year warranty covering manufacturing defects. Rareelectrical’s customer support is responsive via email and phone. They were helpful in confirming fitment before our purchase. It is always a good idea to register your product after purchase and keep the original packaging in case you need to file a claim.
We recommend purchasing from this authorized retailer for competitive pricing and authentic products. Buying through Amazon ensures you get the product with Amazon’s A-to-Z guarantee and often faster, more reliable shipping. This is the safest way to ensure you get a genuine Rareelectrical product.
Yes. The water-cooled turbine housing and oil-cooled journal bearing are specifically designed for continuous high-load operation. In our testing, during a five-hour sustained cruise, the turbo performed flawlessly without any signs of overheating or oil breakdown. It is engineered for the marine environment where engines often run at 70-80% load for hours on end.
With proper maintenance, including regular oil changes and cool-down procedures, this turbo should last as long as a factory unit. Typically, in a well-maintained marine diesel, a turbo can last 3,000 to 5,000 hours. The key is consistent oil changes and allowing the engine to idle for a few minutes after a hard run to cool the turbo properly.
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