Yamaha Intercooler Kit with Blow-Off Valve — Install Guide

GT40 Marine | SKU GT40-YAM-IC-1819L | Yamaha 1.8L SVHO/SHO Intercooler + BOV | Rev 1.0 — 2026-05-24

Fitment — Yamaha 1.8L Supercharged

This intercooler kit fits the Yamaha 1.8L supercharged (SVHO + SHO) engine family. SHO-trim hulls were factory-equipped with a smaller intercooler than SVHO; this kit standardizes on the larger SVHO-equivalent geometry that supports Stage 2+ boost levels.

| Model | Years | Trim |

|---|---|---|

| FX Cruiser SHO | 2008-2016 | SHO supercharged |

| FX SHO | 2008-2015 | SHO supercharged |

| FX Cruiser SVHO | 2014-2023 | SVHO supercharged |

| FX SVHO | 2014-2023 | SVHO supercharged |

| FX Limited SVHO | 2018-2023 | SVHO supercharged |

| GP1800R SVHO | 2019-2023 | SVHO supercharged |

| FZR | 2012-2016 | SHO supercharged |

| FZS | 2012-2016 | SHO supercharged |

Not for: 1.9L (2024+) — Yamaha changed the intercooler architecture in the 1.9L revision; that platform requires a different kit. Not for naturally-aspirated HO trims (no boost = no intercooler needed). Not for 1503 4-TEC platforms. Confirm engine displacement (1.8L) AND trim (SVHO or SHO) before install.

Before You Start — Decision Tree

| # | Question | Branch |

|---|---|---|

| 1 | Engine cover plate confirms 1.8L SVHO or SHO? | Continue |

| 2 | Are you running a tune above stock? | Stage 2+ tune is recommended pairing — this kit is built for higher boost than stock |

| 3 | Do you have a free-flow exhaust + intake already? | If yes, full Stage 2 path is unlocked; if no, gain will be modest until those land |

| 4 | Saltwater operation? | Plan annual freshwater-flush corrosion-check per Service section |

In the Box

(1) GT40 high-capacity intercooler, aluminum, ceramic-coated
(2) GT40-formed charge tubes (inlet + outlet)
(1) Blow-off valve, billet, spring-actuated
(1) BOV mounting flange, welded to outlet tube
(4) Silicone couplers, reinforced charge-grade
(8) T-bolt clamps, stainless
(1) Vacuum reference line, 6 ft silicone, 4 mm ID
(4) Spring vacuum-line clamps
(4) M8 × 25 mm SHCS — intercooler mounting
(4) M8 stainless flat washers
(2) M6 × 25 mm SHCS — BOV-to-flange
(1) Marine-grade thread sealant tube
(1) Install hardware bag — spare couplers, spare clamps
(1) GT40 product registration card
(1) This guide

Tools Required

8 mm / 10 mm / 13 mm sockets + ratchet
T25 + T30 Torx drivers
4 mm + 5 mm + 6 mm hex keys
1/4" + 3/8" drive torque wrenches, 5–25 Nm range
Hose-clamp pliers
Marine-grade thread sealant applicator
Flashlight or headlamp
Shop towels — residual condensate from disconnected intercooler

Safety

Battery disconnected for duration
Cold engine only — supercharger and intercooler reach significant temperature
Eye protection when disconnecting charge tubing — residual condensate sprays
Hand protection when handling ceramic-coated tubing
No smoking / open flame
Two-person lift recommended for intercooler positioning — bulky, awkward in tight engine bay

Pre-Install Checklist

[ ] Watercraft on stable trailer or stand
[ ] Battery negative disconnected and isolated
[ ] Engine bay clean and dry
[ ] Stock intercooler + charge tubing routing photographed
[ ] All 4 supplied silicone couplers matched to tube ends (varying ID)
[ ] BOV pre-assembled to flange, hand-tight only

Step-by-Step Install

Step 1 — Access the Engine Bay

Remove seat. Open engine bay top hatch. Disconnect battery negative terminal.

Step 2 — Remove the Stock Intercooler and Charge Tubing

The Yamaha 1.8L SHO/SVHO architecture uses:

Inlet charge tube from supercharger outlet to intercooler inlet
Stock intercooler mounted on engine bay sidewall
Outlet charge tube from intercooler to throttle body

Removal:

Loosen all four clamps on inlet tube (supercharger end + intercooler inlet end)
Pull inlet tube free — catch residual condensate with shop towel
Loosen four clamps on outlet tube (intercooler outlet + throttle body end)
Pull outlet tube free
Disconnect coolant lines feeding the intercooler (Yamaha intercoolers are typically water-cooled — 2 hose connections, spring clamps)
Remove 4 M8 mounting fasteners
Lift intercooler out — ~6 lbs

Set stock components aside (retain if you may sell craft in stock form).

Step 3 — Install GT40 Intercooler

Position new GT40 intercooler against engine bay mounting bosses
Thread 4 M8 × 25 mm SHCS with flat washers
Snug evenly, torque to 18 Nm (13 ft-lb) in cross pattern, two passes
Reconnect water cooling lines to the intercooler (2 hose connections, spring clamps)

Step 4 — Pre-Fit and Install Charge Tubing

Slide T-bolt clamps + silicone couplers onto supercharger outlet
Insert GT40 inlet charge tube, ceramic-coated side outboard
Slide T-bolt clamps + couplers onto intercooler inlet
Lower inlet tube into position — coupler engagement 1/2 in. minimum each end
Rotate tube for clearance from throttle linkage + harness loom (10 mm minimum)
Repeat for outlet tube — intercooler outlet → throttle body, with BOV flange facing outboard

Step 5 — Torque Charge-Tube Clamps

Sequence: supercharger-end of inlet, intercooler-inlet end, intercooler-outlet end, throttle-body end. Torque each T-bolt clamp to 5 Nm (44 in-lb) alternating in two passes.

Pull-test each joint after torque.

Step 6 — Install BOV on Outlet Tube Flange

Position BOV body against the flange with supplied gasket
Thread 2 M6 × 25 mm SHCS through BOV into flange
Torque to 10 Nm (89 in-lb) with 5 mm hex socket
Confirm BOV outlet points outboard — discharge vents to engine bay, not into hull

Step 7 — Route Vacuum Reference Line

Locate factory MAP sensor port on intake manifold
Cut supplied 4 mm silicone line to length — direct route, no excess loop
Push ends onto BOV vacuum nipple and MAP port — secure with spring clamps
Verify line has no kinks, no contact with hot exhaust

Step 8 — Reassembly and First Start

Walk engine bay — every fastener, every clamp
Reconnect battery negative — torque to 10 Nm
Connect cooling flush hose
Start engine on trailer — idle 60 seconds, listen for boost leaks (lean stumble = leak)
Bring to 3000 RPM briefly — confirm BOV opens on throttle close
Scan with Yamaha YDS — no fault codes (P0238 indicates charge-side leak)

If clean: install complete.

Post-Install

Break-In

First water test: conservative throttle for first 5 minutes — gradual ramp to half throttle, then full pulls. Ceramic coating completes first heat-cure cycle.

Tuning

Stage 2 tune is the matched calibration for this kit. Stock tune yields 5-8 HP; Stage 2 tune yields 15-25 HP gain when paired with intake + exhaust.

Service

Inspect couplers + clamps every 25 hours — retorque if relaxed
Inspect vacuum reference line every 50 hours
Coolant flow check on the water-cooled intercooler annually
Saltwater: rinse intercooler exterior with fresh water after every saltwater session

Troubleshooting

| Symptom | Likely Cause | Fix |

|---|---|---|

| Lean stumble at high RPM | Charge-side leak | Recheck coupler torque |

| BOV doesn't open on lift | Vacuum line disconnected | Reseat vacuum line |

BOV opens at low load	Vacuum line on wrong port	Verify MAP-side port
Check Engine + P0238	Boost-side leak	Recheck all 4 couplers
Excessive engine bay heat	Insufficient coolant flow	Verify intercooler coolant lines connected

Torque Reference Summary

| Fastener | Torque |

|---|---|

| Intercooler M8 SHCS (4) | 18 Nm / 13 ft-lb |

| Charge tube T-bolt clamps | 5 Nm / 44 in-lb |

| BOV M6 SHCS | 10 Nm / 89 in-lb |

| Vacuum spring clamps | Hand-set |

| Battery negative | 10 Nm / 89 in-lb |

Warranty

90-day GT40 warranty per the standard policy. Does not cover improper installation, boost above the BOV-rated ceiling (typically 18 psi for SVHO), saltwater corrosion without anode protection, or use outside fitment.

Claims: support@gt40marine.com.

Support

Email: support@gt40marine.com
Site: gt40marine.com
Install help: include SKU, hull HIN, trim (SVHO or SHO), and tune status in correspondence

Built in the United States. Designed for buyers who want the best.

Yamaha Intercooler Kit with Blow-Off Valve — Install Guide

GT40 Marine | SKU GT40-YAM-IC-1819L | Yamaha 1.8L SVHO/SHO Intercooler + BOV | Rev 1.0 — 2026-05-24

Fitment — Yamaha 1.8L Supercharged

| Model | Years | Trim |

|---|---|---|

| FX Cruiser SHO | 2008-2016 | SHO supercharged |

| FX SHO | 2008-2015 | SHO supercharged |

| FX Cruiser SVHO | 2014-2023 | SVHO supercharged |

| FX SVHO | 2014-2023 | SVHO supercharged |

| FX Limited SVHO | 2018-2023 | SVHO supercharged |

| GP1800R SVHO | 2019-2023 | SVHO supercharged |

| FZR | 2012-2016 | SHO supercharged |

| FZS | 2012-2016 | SHO supercharged |

Before You Start — Decision Tree

| # | Question | Branch |

|---|---|---|

| 1 | Engine cover plate confirms 1.8L SVHO or SHO? | Continue |

| 2 | Are you running a tune above stock? | Stage 2+ tune is recommended pairing — this kit is built for higher boost than stock |

| 3 | Do you have a free-flow exhaust + intake already? | If yes, full Stage 2 path is unlocked; if no, gain will be modest until those land |

| 4 | Saltwater operation? | Plan annual freshwater-flush corrosion-check per Service section |

In the Box

(1) GT40 high-capacity intercooler, aluminum, ceramic-coated
(2) GT40-formed charge tubes (inlet + outlet)
(1) Blow-off valve, billet, spring-actuated
(1) BOV mounting flange, welded to outlet tube
(4) Silicone couplers, reinforced charge-grade
(8) T-bolt clamps, stainless
(1) Vacuum reference line, 6 ft silicone, 4 mm ID
(4) Spring vacuum-line clamps
(4) M8 × 25 mm SHCS — intercooler mounting
(4) M8 stainless flat washers
(2) M6 × 25 mm SHCS — BOV-to-flange
(1) Marine-grade thread sealant tube
(1) Install hardware bag — spare couplers, spare clamps
(1) GT40 product registration card
(1) This guide

Tools Required

8 mm / 10 mm / 13 mm sockets + ratchet
T25 + T30 Torx drivers
4 mm + 5 mm + 6 mm hex keys
1/4" + 3/8" drive torque wrenches, 5–25 Nm range
Hose-clamp pliers
Marine-grade thread sealant applicator
Flashlight or headlamp
Shop towels — residual condensate from disconnected intercooler

Safety

Battery disconnected for duration
Cold engine only — supercharger and intercooler reach significant temperature
Eye protection when disconnecting charge tubing — residual condensate sprays
Hand protection when handling ceramic-coated tubing
No smoking / open flame
Two-person lift recommended for intercooler positioning — bulky, awkward in tight engine bay

Pre-Install Checklist

[ ] Watercraft on stable trailer or stand
[ ] Battery negative disconnected and isolated
[ ] Engine bay clean and dry
[ ] Stock intercooler + charge tubing routing photographed
[ ] All 4 supplied silicone couplers matched to tube ends (varying ID)
[ ] BOV pre-assembled to flange, hand-tight only

Step-by-Step Install

Step 1 — Access the Engine Bay

Remove seat. Open engine bay top hatch. Disconnect battery negative terminal.

Step 2 — Remove the Stock Intercooler and Charge Tubing

The Yamaha 1.8L SHO/SVHO architecture uses:

Inlet charge tube from supercharger outlet to intercooler inlet
Stock intercooler mounted on engine bay sidewall
Outlet charge tube from intercooler to throttle body

Removal:

Loosen all four clamps on inlet tube (supercharger end + intercooler inlet end)
Pull inlet tube free — catch residual condensate with shop towel
Loosen four clamps on outlet tube (intercooler outlet + throttle body end)
Pull outlet tube free
Disconnect coolant lines feeding the intercooler (Yamaha intercoolers are typically water-cooled — 2 hose connections, spring clamps)
Remove 4 M8 mounting fasteners
Lift intercooler out — ~6 lbs

Set stock components aside (retain if you may sell craft in stock form).

Step 3 — Install GT40 Intercooler

Position new GT40 intercooler against engine bay mounting bosses
Thread 4 M8 × 25 mm SHCS with flat washers
Snug evenly, torque to 18 Nm (13 ft-lb) in cross pattern, two passes
Reconnect water cooling lines to the intercooler (2 hose connections, spring clamps)

Step 4 — Pre-Fit and Install Charge Tubing

Slide T-bolt clamps + silicone couplers onto supercharger outlet
Insert GT40 inlet charge tube, ceramic-coated side outboard
Slide T-bolt clamps + couplers onto intercooler inlet
Lower inlet tube into position — coupler engagement 1/2 in. minimum each end
Rotate tube for clearance from throttle linkage + harness loom (10 mm minimum)
Repeat for outlet tube — intercooler outlet → throttle body, with BOV flange facing outboard

Step 5 — Torque Charge-Tube Clamps

Sequence: supercharger-end of inlet, intercooler-inlet end, intercooler-outlet end, throttle-body end. Torque each T-bolt clamp to 5 Nm (44 in-lb) alternating in two passes.

Pull-test each joint after torque.

Step 6 — Install BOV on Outlet Tube Flange

Position BOV body against the flange with supplied gasket
Thread 2 M6 × 25 mm SHCS through BOV into flange
Torque to 10 Nm (89 in-lb) with 5 mm hex socket
Confirm BOV outlet points outboard — discharge vents to engine bay, not into hull

Step 7 — Route Vacuum Reference Line

Locate factory MAP sensor port on intake manifold
Cut supplied 4 mm silicone line to length — direct route, no excess loop
Push ends onto BOV vacuum nipple and MAP port — secure with spring clamps
Verify line has no kinks, no contact with hot exhaust

Step 8 — Reassembly and First Start

Walk engine bay — every fastener, every clamp
Reconnect battery negative — torque to 10 Nm
Connect cooling flush hose
Start engine on trailer — idle 60 seconds, listen for boost leaks (lean stumble = leak)
Bring to 3000 RPM briefly — confirm BOV opens on throttle close
Scan with Yamaha YDS — no fault codes (P0238 indicates charge-side leak)

If clean: install complete.

Post-Install

Break-In

First water test: conservative throttle for first 5 minutes — gradual ramp to half throttle, then full pulls. Ceramic coating completes first heat-cure cycle.

Tuning

Stage 2 tune is the matched calibration for this kit. Stock tune yields 5-8 HP; Stage 2 tune yields 15-25 HP gain when paired with intake + exhaust.

Service

Inspect couplers + clamps every 25 hours — retorque if relaxed
Inspect vacuum reference line every 50 hours
Coolant flow check on the water-cooled intercooler annually
Saltwater: rinse intercooler exterior with fresh water after every saltwater session

Troubleshooting

| Symptom | Likely Cause | Fix |

|---|---|---|

| Lean stumble at high RPM | Charge-side leak | Recheck coupler torque |

| BOV doesn't open on lift | Vacuum line disconnected | Reseat vacuum line |

BOV opens at low load	Vacuum line on wrong port	Verify MAP-side port
Check Engine + P0238	Boost-side leak	Recheck all 4 couplers
Excessive engine bay heat	Insufficient coolant flow	Verify intercooler coolant lines connected

Torque Reference Summary

| Fastener | Torque |

|---|---|

| Intercooler M8 SHCS (4) | 18 Nm / 13 ft-lb |

| Charge tube T-bolt clamps | 5 Nm / 44 in-lb |

| BOV M6 SHCS | 10 Nm / 89 in-lb |

| Vacuum spring clamps | Hand-set |

| Battery negative | 10 Nm / 89 in-lb |

Warranty

Claims: support@gt40marine.com.

Support

Email: support@gt40marine.com
Site: gt40marine.com
Install help: include SKU, hull HIN, trim (SVHO or SHO), and tune status in correspondence

Built in the United States. Designed for buyers who want the best.