TOMEI ENG O H KIT FULL BL5 BP5 93.5-1.5 FOR SUBARU IMPREZA WRX STI EJ20 1964493151

 

TOMEI ENG O H KIT FULL BL5 BP5 93.5-1.5 FOR SUBARU IMPREZA WRX STI EJ20 1964493151

The TOMEI ENGINE O/H KIT Full for EJ20 BL5/BP5, 93.5 mm bore × 1.5 mm head-gasket thickness, P/N 1964493151 is essentially a comprehensive engine-rebuild gasket/sealing package, rather than a horsepower-producing engine kit. 

TOMEI lists it specifically for the EJ20 used in the Subaru Legacy B4 BL5 and Legacy Touring Wagon BP5. 

🔧 What the kit contains

According to TOMEI, the Full Kit combines:

• TOMEI metal head gasket
• Timing belt
• Timing-belt guide
• Oil filler cap
• Various gaskets and seals required during an engine overhaul
• Full-kit components that are not included in the cheaper pulley-less version 

The important specification is:

Specification	1964493151
Engine	Subaru EJ20
Application	BL5 / BP5
Kit	Full O/H Kit
Head-gasket bore	93.5 mm
Head-gasket thickness	1.5 mm
Part number	1964493151
Current TOMEI list price	¥198,000 incl. tax
Kit weight	~6.4 kg

TOMEI currently lists the 1.5-mm version alongside 0.7, 1.0, 1.2 and 1.8-mm alternatives. 

🧠 Why the 1.5-mm gasket matters

The 1.5 mm specification isn’t simply “thicker = stronger.” Head-gasket thickness affects the EJ20’s assembled combustion-chamber geometry and compression ratio.

Conceptually:

Thicker gasket → greater piston-to-head clearance → slightly larger combustion volume → lower compression ratio

while:

Thinner gasket → smaller clearance → slightly smaller combustion volume → higher compression ratio

So the 1.5-mm gasket should be selected according to the actual piston, block/head machining and desired compression ratio, rather than simply choosing it because the engine is modified.

🏁 Why the Full Kit is attractive for an EJ20 rebuild

The clever part of this package is that TOMEI isn’t only supplying a head gasket. It packages many of the consumables that are normally replaced when an EJ20 is opened up.

Think of the rebuild as:

EJ20 teardown → machining/inspection → new sealing system → timing system renewal → reassembly

The kit helps eliminate the situation where a rebuilt engine receives fresh internal components but retains a collection of old seals and timing components.

TOMEI describes the product specifically as a combination of its metal head gasket, timing belt, belt guide and oil filler cap together with the gasket/seal set required for an overhaul. 

⚙️ Full Kit vs Pulley-Less Kit

This is an important distinction:

Full Kit — 1964493151
→ includes the additional pulley-related components

Pulley-Less — 1964493152
→ same 93.5 × 1.5 mm gasket specification, but omits the pulley components.

🔬 Engineering interpretation

For a serious EJ20 rebuild, I’d classify this as:

OEM refresh kit: ★★★★☆
Performance potential: ★★★☆☆
Reliability contribution: ★★★★★
Track-build usefulness: ★★★★★
Direct horsepower gain: ★☆☆☆☆

The key point is that the kit itself doesn’t create big power. Its value is in creating a known, fresh sealing and timing foundation around which you can build the rest of the EJ20.

For a high-output EJ20, the important engineering decisions then become piston-to-wall clearance, ring gap, bearing clearances, deck/head flatness, compression ratio, cylinder sealing, fastener strategy and ECU calibration. The TOMEI kit is one part of that much larger system.

Bottom line: 1964493151 is the 93.5-mm × 1.5-mm Full O/H Kit, and it makes particular sense when you’re doing a genuine EJ20 teardown/rebuild rather than merely replacing a head gasket. 

TOMEI ENG O H KIT FULL BL5 BP5 93.5-1.5 FOR SUBARU IMPREZA WRX STI EJ20 1964493151

 

Dodson Gr6 Sporstman 10 Clutch Kit for Nissan GT-R DMS-8188

The Dodson DMS-8188 Sportsman’s 10-Plate is a serious internal clutch upgrade for the Nissan R35 GT-R’s GR6 dual-clutch transmission. 

Dodson positions it as the step above its Sportsman’s 8- and 9-plate systems, with the 10-plate configuration aimed at very high-output builds. Dodson currently states support for up to 2,000 hp. 

🧠 Technical explanation

Think of the GR6 as having two concentric multi-plate clutch packs:

• A clutch → controls one set of gears
• B clutch → controls the other set
• Both operate in an oil-cooled, hydraulically actuated environment.
• During a gear change, one clutch can progressively release while the other engages.

The DMS-8188 increases the friction interface area dramatically.

10 plates per clutch × 2 clutch packs = 20 friction plates.

More friction interfaces allow the transmission to transmit substantially more torque without requiring the same friction load per individual plate.

🔩 What makes the Sportsman’s 10 special?

Component	DMS-8188 upgrade	Engineering benefit
Friction discs	20 total	Much greater friction capacity
Steel plates	22	High-temperature load capability
A basket	Forged/billet steel	Reduced distortion
B basket	Forged/billet steel	Greater structural rigidity
A piston	Forged aluminium	Lower reciprocating mass
B piston	Forged aluminium	Lower reciprocating mass
Piston seals	Bonded/Viton-type sealing	Better hydraulic sealing
Basket splines	Induction hardened	Improved wear resistance
B-basket bearing	Integrated	Additional support at high rpm

Dodson specifies high-performance friction material together with high-strength, heat-treated steels. 

The forged baskets are particularly important because clutch-basket distortion becomes increasingly problematic as torque and hydraulic loading rise. 

⚙️ Why 10 plates instead of 8 or 9?

The progression is essentially:

8 plate → 9 plate → 10 plate

Dodson lists approximately:

• Sportsman’s 8 → up to 1,600 hp
• Sportsman’s 9 → up to 1,800 hp
• Sportsman’s 10 → up to 2,000 hp

Those are manufacturer capability figures rather than a guarantee that every engine/transmission combination will reliably make those numbers. 

The important engineering principle is torque capacity, not horsepower alone.

At the same horsepower, a high-torque turbo setup can put considerably more instantaneous load through the GR6 than a peaky setup.

🔥 Where the DMS-8188 makes sense

This is aimed at an R35 that has moved far beyond a mildly modified street car:

Stock GR6
↓
Sportsman 8
↓
Sportsman 9
↓

Sportsman 10

↓
Promax 10 / extreme-build territory

The Sportsman’s 10 is therefore a particularly interesting choice for a high-power R35 that still needs a relatively sophisticated dual-clutch driveline rather than converting to a conventional manual transmission.

One key advantage is that you’re not simply throwing in stronger friction discs—the baskets and pistons are upgraded too, addressing the mechanical structure and hydraulic actuation behind the friction material. 

🏁 The deeper engineering picture

The upgrade is really about controlling this chain:

Engine torque

→ crankshaft

→ transmission input

→ A/B clutch packs

→ GR6 gearsets

→ transfer system

→ differentials

→ driveshafts

→ 4WD

The clutch is effectively the torque gatekeeper.

If the friction material cannot maintain sufficient friction coefficient under temperature and pressure, the clutch begins to slip. 

Slip generates heat, heat degrades the friction interface, and degradation increases slip—a nasty feedback loop.

The DMS-8188 attacks that problem through more friction interfaces + stronger baskets + stronger pistons + improved sealing + heat-resistant friction/steel components.

🆚 Sportsman 10 vs Sportsman 8

	Sportsman 8	Sportsman 9	Sportsman 10
Friction plates	16	18	20
Plates per clutch	8	9	10
Dodson claimed power	~1,600 hp	~1,800 hp	~2,000 hp
Forged baskets	✅	✅	✅
Forged pistons	✅	✅	✅
Intended level	High-performance	Very high-performance	Extreme high-output

The 10-plate kit is therefore not merely a “better clutch disc.” It is a substantially reinforced GR6 clutch assembly.

Bottom line: DMS-8188 is the kind of component you choose when the GR6 itself has become one of the limiting components of a heavily modified R35 GT-R. 

For a genuinely high-output VR38 build, the clutch upgrade should be considered together with the GR6 gearset, transmission control/calibration, cooling and drivetrain torque management—not as an isolated component. 

Dodson Gr6 Sporstman 10 Clutch Kit for Nissan GT-R DMS-8188