HKS Super SQV4 Blow Off Valve for 2017-2021 Civic Si/1.5T

HKS Super SQV4 Blow Off Valve - 2017-2021 Honda Civic Si / 1.5T

The stock bypass valve on your 10th gen Civic 1.5T works but you can't hear it. You're building boost, you lift off the throttle, and nothing. No sound. No presence. HKS's Super Sequential Blow Off Valve (SSQV4) fixes that. You're getting that crisp high-pitched SSQV release sound every time you lift. HKS makes two versions for the 10th gen Civic 1.5T and you need to pick the right one before you order. Part number 71008-AH010 is the complete kit with the SSQV4 valve and the full recirculation hose setup. Part number 71008-AH011 is just the SSQV4 valve with no recirculation hardware. Both use the same valve. The difference is where the vented air goes. The AH010 recirculates the air back into the intake. The AH011 vents it to atmosphere. Pick based on your setup and whether you're in an emissions-tested state.

Here's the Difference Between the Two Versions

The 71008-AH010 is the complete recirculation kit. You're getting the SSQV4 valve, all the hoses, all the adapters, and all the mounting hardware. The vented air routes back into the intake tract so the system stays closed loop. This is the version you want if you're daily driving the car, if you live in a state with emissions testing, or if you just want the SSQV sound without venting to atmosphere. The 71008-AH011 is just the SSQV4 valve. No recirculation hardware. The vented air goes straight to atmosphere for a louder, more pronounced whoosh when you lift off boost. This is the version for track cars, non-emissions-tested applications, or builds that are already running custom charge piping where you don't need HKS's recirculation setup. The Civic 1.5T uses a MAP sensor for fueling, not a MAF, so venting to atmosphere won't cause the air-fuel measurement problems you'd see on a MAF-based car. Both versions work fine on this engine. The recirculation question is about emissions compliance and how loud you want it.

Sequential Valve Structure with Differential Pressure Control

Most blow off valves use a spring. You set the spring preload for your boost level and if you change the boost later, you're readjusting the spring. HKS's SSQV4 doesn't work like that. It uses a sequential valve structure with a differential pressure control system. The valve opens based on the pressure differential between the charge pipe and the intake manifold, not a fixed spring threshold. It works from low boost to high boost without adjustment. You're running 10 PSI? It opens. You're running 20 PSI? It opens. You crank the boost to 25 PSI next year? It still works. No spring adjustment. No retuning. It's self-regulating. Connect the SSQV4 to the intake manifold vacuum port and it handles the rest.

Pull-Type Relief Design

The SSQV4 is a pull-type valve. When you lift off the throttle, the intake manifold goes into vacuum. That vacuum signal pulls the valve open and releases the pressure from the charge pipe. Most cheap blow off valves are push-type. The boost pressure pushes the valve open against a spring. The problem with push-type valves is the operation's inconsistent. At low boost the valve barely opens. At high boost it slams open. The SSQV4's pull-type design keeps the operation smooth and stable at any boost level. The valve opens cleanly every time you lift. You're getting that signature SSQV sound and you're protecting the turbo from compressor surge.

Pick Your Version

If you're not sure which version you need, here's the breakdown. Buy the 71008-AH010 complete kit if you're daily driving the car, if you live in a state with emissions testing, or if you want the SSQV sound without venting to atmosphere. The recirculation kit keeps the system closed loop and it's a direct bolt-on for the stock Civic 1.5T charge pipe setup. Buy the 71008-AH011 valve-only if you're building a track car, if you're in a non-emissions-tested state, or if you're already running custom charge piping and you don't need the recirculation hardware. If you already own the AH011 and you want to add recirculation later, HKS sells the Return Kit Plus as a standalone add-on. If you're still not sure, reach out before you order.

What You Get

• HKS Super Sequential Blow Off Valve (SSQV4) for 10th gen Civic 1.5T
• Two versions available:
  • 71008-AH010: Complete kit with SSQV4 valve + full recirculation hose setup (vents back into intake, closed loop, emissions-compliant)
  • 71008-AH011: SSQV4 valve only (vents to atmosphere, louder sound, no recirculation hardware)
• Sequential valve structure with differential pressure control (works low to high boost without adjustment)
• Pull-type relief design (stable operation regardless of boost level)
• No spring adjustment required (self-regulating via pressure differential)
• High-pitched crisp SSQV release sound
• Made by HKS

Fits These Cars

• 2016-2021 Honda Civic Sedan/Coupe 1.5T
• 2017-2021 Honda Civic Hatchback 1.5T
• 2017-2021 Honda Civic Si

Note: Two versions available - 71008-AH010 (complete recirculation kit) or 71008-AH011 (valve only, vents to atmosphere). Pick based on emissions requirements and sound preference. 71008-AH010 complete kit includes SSQV4 valve, all hoses, adapters, and mounting hardware for recirculation (vented air routes back into intake, closed loop, emissions-compliant, recommended for street cars and daily drivers). 71008-AH011 valve only vents to atmosphere (louder sound, no recirculation hardware, for track cars or custom charge piping setups). Civic 1.5T uses MAP sensor (not MAF) so venting to atmosphere won't cause air-fuel measurement problems like it would on MAF-based cars. Sequential valve structure with differential pressure control works across full boost range without adjustment (no spring tuning required). Pull-type relief design (intake manifold vacuum pulls valve open) for smooth consistent operation at any boost level. Protects turbo from compressor surge. Direct bolt-on for stock charge pipe setup (AH010 kit). If you own AH011 and want to add recirculation later, HKS sells Return Kit Plus as standalone add-on. Does NOT fit FK8 Civic Type R (Type R uses different charge pipe layout and requires different HKS application). Professional installation recommended.