Rb25de+t Headgasket Options..

[Paulusc44]

Hey all,

Have just pulled the head off my R32 RB25DE+T..

Which of course runs the current standard headgasket and a CP of 10:1.. How thick is the headgasket in the standard RB25DE?

I know the RB25DET runs a CP of 9:1.. Technically the only difference between the DE and DET Blocks are the under-piston oil squirters?

Im also upgrarding injectors to GTR 440's, AFM to a Z32 item and the turbo to a T3/T4 frame item, which will be running 10-12 PSI MAX @ est 220-230 KW

Because Im only running a max of 10 PSI Im keen to keep the CP at the standard 10:1 but I'd quite like to go for a steel item, is this necessary at this boost level on the DE?

If so what thickness are the standard 25DE headgaskets? Or am I simply best to get a genuine 25DE one from my local Nissan dealership? Will this hold fine?

Info on where and what would be cool, all helps appreciated!

Cheers again!

[iruvyouskyrine]

Standard headgasket is 1.3mm

Standard nissan headgasket is fine

Keep it 10:1

T3/T4 is not a turbo size and means nothing

[GTSBoy]

Further to this, Compression Patio is not a thing. Whereas Compression Ratio actually is.

As to the specifics of gasket types and thicknesses relative to your boost and the CR you're looking for;

• Head gasket thickness is not what is used by the OEM to set/control the CR. The thickness can be used to tweak it a little bit, but it's not a big tool.
• The CR is determined pretty much by the swept capacity (which is fixed for any given engine) and the piston crown shape and head chamber volume. That is where the difference between DE and DET engines is to be found. Not the gasket.
• You don't need a steel gasket for low boost.
• The Nissan gaskets are great at even up to quite high boost.
• No gasket is any good unless you make damn sure the mating surfaces are straight and clean, which is the step that is often missed by DIYers that leads to people complaining about blown head gaskets.

[Paulusc44]

Standard headgasket is 1.3mm

Standard nissan headgasket is fine

Keep it 10:1

T3/T4 is not a turbo size and means nothing

I know T3/T4 Isnt an actual turbo sizing haha, Was just letting people know roughly what size of compressor I was planning on using, Cheers though sounds like the standard Nissan gasket is the way to go

Further to this, Compression Patio is not a thing. Whereas Compression Ratio actually is.

As to the specifics of gasket types and thicknesses relative to your boost and the CR you're looking for;

• Head gasket thickness is not what is used by the OEM to set/control the CR. The thickness can be used to tweak it a little bit, but it's not a big tool.
• The CR is determined pretty much by the swept capacity (which is fixed for any given engine) and the piston crown shape and head chamber volume. That is where the difference between DE and DET engines is to be found. Not the gasket.
• You don't need a steel gasket for low boost.
• The Nissan gaskets are great at even up to quite high boost.
• No gasket is any good unless you make damn sure the mating surfaces are straight and clean, which is the step that is often missed by DIYers that leads to people complaining about blown head gaskets.

Hahaha yeah I have no idea why I put CP.. Was looking for CR haha.. I understand the Piston Crown and Combustion Chamber shape is what ultimately gives the difference in CR, but after researching the likes of the Tomei, Cometic gaskets etc and seeing the endless options in between 1.1 and 1.7 mm (some even slightly higher) to slightly change compression ratios I was wondering if Nissan had just slipped something super thin in the DE. Cheers for clearing that up man

[Paulusc44]

Further to this, Compression Patio is not a thing. Whereas Compression Ratio actually is.

As to the specifics of gasket types and thicknesses relative to your boost and the CR you're looking for;

• Head gasket thickness is not what is used by the OEM to set/control the CR. The thickness can be used to tweak it a little bit, but it's not a big tool.
• The CR is determined pretty much by the swept capacity (which is fixed for any given engine) and the piston crown shape and head chamber volume. That is where the difference between DE and DET engines is to be found. Not the gasket.
• You don't need a steel gasket for low boost.
• The Nissan gaskets are great at even up to quite high boost.
• No gasket is any good unless you make damn sure the mating surfaces are straight and clean, which is the step that is often missed by DIYers that leads to people complaining about blown head gaskets.

Just have one more quick question, that I have researched but Illl just clear it up with you anyways.. The R32/A31 Spec RB25DE has the same 87.0 mm bore as the S1 S2 RB25DET, correct?

[GTSBoy]

All 25s are the same.

[iruvyouskyrine]

86.0mm is virgin bore