---
title: "ql78yc marine spark plug — Niche Verdict: Worth a look (59/100) | Amazon United States - Flapen"
canonical_url: "https://flapen.com/amazon/research/us/automotive/ql78yc-marine-spark-plug"
last_updated: "2026-07-14T05:12:46.482Z"
locale: en
meta:
  description: "ql78yc marine spark plug shows demand growing +175.7% this quarter, but a failed launch gate (market size, growth, or returns) keeps it on the watch list."
  "og:description": "ql78yc marine spark plug shows demand growing +175.7% this quarter, but a failed launch gate (market size, growth, or returns) keeps it on the watch list."
  "og:title": "ql78yc marine spark plug — Niche Verdict: Worth a look (59/100) | Amazon United States - Flapen"
---

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# **ql78yc marine spark plug**

**Worth a look**

Shows demand growing +175.7% this quarter, but a failed launch gate (market size, growth, or returns) keeps it on the watch list.

Market size 9Growth 97Conversion 96Competition 8Returns 84Price range 95Avg price 95Brand share 12Review moat 94Quality gap 81

**Growth**

**Incredible****+175.7%**

90-day search growth — must beat 0% to launch

**Conversion**

**Incredible****14.1%**

search→purchase rate — share of searches ending in a sale

**Avg price**

**Incredible****$23.17**

avg listing price — sweet spot $15–$100

**Price range**

**Incredible****$16.65–$31.76**

cheapest to priciest tracked listing — scored on the share inside $15–$100

**Review moat**

**Great****115.44**

avg incumbent reviews — the moat a new listing must climb

**Returns**

**Great****1.5%**

return rate — above 6% kills the launch gate

**Quality gap**

**Great****4.2★**

avg incumbent rating — lower means beatable quality

**Brand share**

**Bad****95%**

top-5 brand share — brand-locked demand

**Market size**

**Bad****$35K**

$35K/yr · 11K searches

**Competition**

**Bad****90%**

top-5 click share — a locked-up shelf

## **Competition**

The top 5 products capture 90% of clicks — a locked-up shelf that new listings rarely crack.

**Brands**

**7 **▲rising

**Sellers**

**27**

**Top-5 brand share**

**95%**

**Open market**

**2%**

- Champion53% - MEILAN30% - yeeluzan6% - BDFHYK3% - UMONIE3% - SYKRSS3% - Open — no brand owns it (1 brand, 2%)

## **Product shelf**

Each bubble is one product — market share against review moat; bubble size tracks estimated sales, color grades how beatable the incumbent looks.

0%15%$5K30%$11K45%$16K60%$21K1101001K Reviews — right = deep review moatMarket share (90d) ≈ est. sales

Beatable (≤4.3★) Contested Strong incumbent (>4.7★)

All 9 tracked products in this niche — three views at once, no toggling.

### **Top sellers**

by 90-day click share

[1![Champion QL78YC Spark Plug Pack of 4](https://m.media-amazon.com/images/I/41MwPgWgyeL.jpg)**Champion QL78YC Spark Plug Pack of 4**Champion**$18.54**4.7★438 rev](https://www.amazon.com/dp/B002TRAU34) [2![SPARK PLUGS 6 PACK MARINE ENGINES 24 QL78YC 938M OUTBOARDS INBOARD I/O CHAMPION](https://m.media-amazon.com/images/I/41f1mCYuupL.jpg)**SPARK PLUGS 6 PACK MARINE ENGINES 24 QL78YC 938M OUTBOARDS INBOARD I/O CHAMPION**MEILAN**$29.67**4.7★188 rev](https://www.amazon.com/dp/B0872RV1B1) [3![Champion QL78YC (938M) Marine 8 Pack](https://m.media-amazon.com/images/I/51sGNWqzrVL.jpg)**Champion QL78YC (938M) Marine 8 Pack**Champion**$31.76**4.6★200 rev](https://www.amazon.com/dp/B00JBK83AE) [4![8PCS Iridium Spark Plugs Fit for Johnson Evinrude Mercury Marine Outboard Engines Replacement for QL78YC 938M](https://m.media-amazon.com/images/I/41veKMbU4SL.jpg)**8PCS Iridium Spark Plugs Fit for Johnson Evinrude Mercury Marine Outboard Engines Replacement for QL78YC 938M**yeeluzan**$22.65**4.2★9 rev](https://www.amazon.com/dp/B0FGCMMK4X) [5![BDFHYK QL78YC Iridium Spark Plugs Compatible with Mercury Evinrude Johnson Mariner OMC Set of 4](https://m.media-amazon.com/images/I/41QQidgjZ8L.jpg)**BDFHYK QL78YC Iridium Spark Plugs Compatible with Mercury Evinrude Johnson Mariner OMC Set of 4**BDFHYK**$16.65**4.4★17 rev](https://www.amazon.com/dp/B0DJVY97MH)

**~~View all top sellers →~~**

### **Newest**

by launch date

[![SYKRSS QL78YC Marine Spark Plugs 4 Pack - Compatible with Mercury/Mariner EFI Evinrude 10-225HP (1973-2001) Johnson 10E-90HP (1974-2005) - Replaces QL77JC4 for 2/4-Stroke Outboard Motors](https://m.media-amazon.com/images/I/41p5KFoLGxL.jpg)**SYKRSS QL78YC Marine Spark Plugs 4 Pack - Compatible with Mercury/Mariner EFI Evinrude 10-225HP (1973-2001) Johnson 10E-90HP (1974-2005) - Replaces QL77JC4 for 2/4-Stroke Outboard Motors**SYKRSS**$16.71**157 rev9mo ago](https://www.amazon.com/dp/B0FLXSX6JN) [![8PCS Iridium Spark Plugs Fit for Johnson Evinrude Mercury Marine Outboard Engines Replacement for QL78YC 938M](https://m.media-amazon.com/images/I/41veKMbU4SL.jpg)**8PCS Iridium Spark Plugs Fit for Johnson Evinrude Mercury Marine Outboard Engines Replacement for QL78YC 938M**yeeluzan**$22.65**9 rev1y ago](https://www.amazon.com/dp/B0FGCMMK4X) [![8 Pack ql78yc marine spark plug - 938M Replacement for champion ql78yc Compatible with Johnson Evinrude Mercury Marine Engines (Outboard/Inboard) Replaces BPZ8HS10 Wont fit Ford 150](https://m.media-amazon.com/images/I/51rCpyn4lcL.jpg)**8 Pack ql78yc marine spark plug - 938M Replacement for champion ql78yc Compatible with Johnson Evinrude Mercury Marine Engines (Outboard/Inboard) Replaces BPZ8HS10 Wont fit Ford 150**UMONIE**$21.53**9 rev1y ago](https://www.amazon.com/dp/B0FDB36SX4) [![BDFHYK QL78YC Iridium Spark Plugs Compatible with Mercury Evinrude Johnson Mariner OMC Set of 4](https://m.media-amazon.com/images/I/41QQidgjZ8L.jpg)**BDFHYK QL78YC Iridium Spark Plugs Compatible with Mercury Evinrude Johnson Mariner OMC Set of 4**BDFHYK**$16.65**17 rev1y ago](https://www.amazon.com/dp/B0DJVY97MH) [![YUXIVCNE 6 Pack Spark Plugs QL78YC 938M Replacement for Johnson Evinrude for Mercury Outboards Inboard Marine Engines Parts Replace BPZ8HS10](https://m.media-amazon.com/images/I/41qmA4buKFL.jpg)**YUXIVCNE 6 Pack Spark Plugs QL78YC 938M Replacement for Johnson Evinrude for Mercury Outboards Inboard Marine Engines Parts Replace BPZ8HS10**YUXIVCNE**$22.63**11 rev1y ago](https://www.amazon.com/dp/B0DC9D2SW1)

**~~View all new products →~~**

### **Trending**

90-day click momentum

[![Champion QL78C L78C BH8S (807M) Marine 8 Pack](https://m.media-amazon.com/images/I/514M5UAjOAL.jpg)**Champion QL78C L78C BH8S (807M) Marine 8 Pack**Champion**$28.42**3.3★**▲ 84%**](https://www.amazon.com/dp/B00KAZHUZS) [![8PCS Iridium Spark Plugs Fit for Johnson Evinrude Mercury Marine Outboard Engines Replacement for QL78YC 938M](https://m.media-amazon.com/images/I/41veKMbU4SL.jpg)**8PCS Iridium Spark Plugs Fit for Johnson Evinrude Mercury Marine Outboard Engines Replacement for QL78YC 938M**yeeluzan**$22.65**4.2★**▲ 78%**](https://www.amazon.com/dp/B0FGCMMK4X) [![Champion QL78YC Spark Plug Pack of 4](https://m.media-amazon.com/images/I/41MwPgWgyeL.jpg)**Champion QL78YC Spark Plug Pack of 4**Champion**$18.54**4.7★**▲ 13%**](https://www.amazon.com/dp/B002TRAU34) [![SYKRSS QL78YC Marine Spark Plugs 4 Pack - Compatible with Mercury/Mariner EFI Evinrude 10-225HP (1973-2001) Johnson 10E-90HP (1974-2005) - Replaces QL77JC4 for 2/4-Stroke Outboard Motors](https://m.media-amazon.com/images/I/41p5KFoLGxL.jpg)**SYKRSS QL78YC Marine Spark Plugs 4 Pack - Compatible with Mercury/Mariner EFI Evinrude 10-225HP (1973-2001) Johnson 10E-90HP (1974-2005) - Replaces QL77JC4 for 2/4-Stroke Outboard Motors**SYKRSS**$16.71**4.2★**— 3%**](https://www.amazon.com/dp/B0FLXSX6JN) [![SPARK PLUGS 6 PACK MARINE ENGINES 24 QL78YC 938M OUTBOARDS INBOARD I/O CHAMPION](https://m.media-amazon.com/images/I/41f1mCYuupL.jpg)**SPARK PLUGS 6 PACK MARINE ENGINES 24 QL78YC 938M OUTBOARDS INBOARD I/O CHAMPION**MEILAN**$29.67**4.7★**— 1%**](https://www.amazon.com/dp/B0872RV1B1)

**~~View all trending →~~**

## **Reviews**

What buyers praise and complain about, mined from review topics.

### **What buyers love **

**Efficiency**30%

*“Works well”*

**Value For Money**25%

*“ordered twice priced well”*

**Quality-Overall**15%

*“Great product”*

**Advertised Vs Actual Product**10%

*“Just what I needed”*

**Motor Power**10%

*“motor runs better then the plugs that were in it”*

**Functionality-Overall**10%

*“spark plugs worked just fine as well as the spark plug wires”*

### **What buyers complain about **

**Functionality-Overall**50%

*“They weren't very efficient”*

**Socket/Port/Plug**50%

*“These plugs are not the plugs meant for the boat motor we entered”*

### **Top return reasons **

**Size-Overall**28%

**Advertised Vs Actual Product**26%

**Compatibility-Overall**16%

**Defective Material/Parts**14%

**Maintenance And Repair**4%

**Motor Issues**4%

**Value For Money**4%

**Quality-Overall**2%

**Socket/Port/Plug**2%