Sierra Premium Marine Spark Plug Wire Set – 47-88291 | MerCruiser Thunderbolt
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Sierra Premium Marine Spark Plug Wire Set – MerCruiser Thunderbolt Ignition
Restore reliable ignition performance to your MerCruiser with this premium spark plug wire set engineered for Thunderbolt ignition systems. Over time, heat cycling, vibration, and moisture cause plug wire insulation to crack and resistance to rise — leading to misfires, rough idle, and reduced power. This Sierra set replaces worn wires with marine-grade materials built to deliver consistent, high-voltage spark in demanding on-water conditions.
Compatible Applications
- MerCruiser engines equipped with Thunderbolt ignition systems
- Refer to Sierra part number 47-88291 application guide for specific engine models and years
Key Features
- Kevlar® core — maximum durability and long service life under continuous vibration
- Stainless steel wound conductor — optimized for maximum horsepower and consistent engine performance
- Premium silicone jacketing and boots — high-temperature protection against engine bay heat
- Superior RFI suppression — shields sensitive onboard electronics from ignition interference
- Corrosion-resistant stainless steel terminals — at both spark plug and distributor ends for maximum conductivity
- OE-style sealed boots — barrier against heat, dirt, and moisture intrusion
- Application-specific magnetic suppression core — precision fit for your engine configuration
Specifications
- Part Number: 47-88291
- Ignition Type: Thunderbolt (MerCruiser)
- Condition: New
Complete Your Ignition Service
For a full tune-up, pair these wires with a matching distributor cap and rotor from our Ignition Components collection. Need a different fitment? Also consider the Sierra Wire Set – 47-88021, 47-88032, 47-88041, 47-88071, 47-88101, 47-88111, 47-88201, 47-88211, 47-88221, or 47-88281. Need a single replacement lead? See the Sierra 6" Spark Plug Wire – 47-88161.
Parts Desk Insights
The 47-88291 is a premium-tier set in this Thunderbolt wire family — priced similarly to the 47-88281 but at a lighter 626g, which points to a specialized engine configuration with a different lead layout rather than a larger cylinder count. It’s the right choice when a Thunderbolt-equipped MerCruiser is misfiring under load, idling roughly, or showing intermittent spark after spark plugs have already been ruled out. As always, replace the full set at once to maintain consistent resistance across all cylinders, and confirm your engine model and year against the Sierra 47-88291 application guide before ordering — fitment is engine-configuration-specific.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.