Forged Pistons?

[25GTT]

Heya Everyone!

Well Am now in planning stage of doing next small stage of mods, hybrid t3/t4 turbo & Fuel Pump

This will put me around 310 rwhp. At what stage will i need forged pistons? will my engine be ok off standard internals running this HP off 14 psi boost from the hybrid turbo

I already have the normal 1st stage of mods eg FMIC, clutch SAFC + ITC (if i can get it working!), oil catch can

But yeah am just worried if i ever end up giving it a bit for sometime would the internals Be ok? any other things i would need for reliability?

[skyzerr33]

for the turbo u might need to loose the SAFC + ITC and get a new ECU but he should be able to tune them for the t3/t4.

want need forgies, but they wouldn't hurt.

[GTS-t VSPEC]

With anything more than 14psi then I would suggest forged pistons, I have a set of Wiseco's going into mine. With the pistons being done I am also porting the head, balance crank, shot piening rods. the pistons will also lower the compression.

Although it is not definate that you will need them , they do add to the overall reliability of the package. The RB25DET pistons have very weak ring lands, so it your investing in a bigger turbo then I'd also do the internals.

my 2c.

See'ya:burnout:

[JimX]

25GTT, I'm just wondering how you're expecting to get 310hp (230kw) at the wheels with those small mods and 14psi. Brendanf is only getting 220kw at 14psi and he's also got a new plenum and throttle body.

I'm not saying you *can't* get those power figures, I just want to know what your theory is so I can do it to mine as well I've got a similar setup to you and I'm only getting 166kw@11psi atm. But most of my restrictiveness is from the really crappy FMIC plumbing, I'm going to get it done properly once I save up the required $400.

[Silver-Arrowz]

My mates S15 was being rebuilt with JUN forgies and when installing it back in, the d*cks forgot to put the vaccum hose back in. Drove it hard for 3 days then they realised the hose wasn't plugged in. Pulled the motor apart and the pistons are still like new.

[25GTT]

Originally posted by JimX

25GTT, I'm just wondering how you're expecting to get 310hp (230kw) at the wheels with those small mods and 14psi. Brendanf is only getting 220kw at 14psi and he's also got a new plenum and throttle body.

I'm not saying you *can't* get those power figures, I just want to know what your theory is so I can do it to mine as well I've got a similar setup to you and I'm only getting 166kw@11psi atm. But most of my restrictiveness is from the really crappy FMIC plumbing, I'm going to get it done properly once I save up the required $400.

Well i pretty much have the same setup besides the Power FC (I have SAFC and ITC) as one of the other guys in WA (WASSABI) and he made 315 rwhp on a VERY legit dyno. My intercooler and piping is quite large and i also have Dump & Down pipe straight from the turbo... at the moment I am pushing 260 rwhp on 12 psi but have recently wound it down to 10 psi which pushed out 251 rwhp. with the ITC installed, fuel pump and t3/t4 turbo i don't think that 310 rwhp is too much out of the question, as long as the injectors hold... I will be happy as long as i hit 300 rwhp.

Is Brendan f running stock turbo @ 14psi?

So by the looks of it forged pistons will have to be considered in the future.... prob when i get some more $$$ maybe if i keep the hp at 300 rwhp until i can afford forged pistons might be the way to go.

[25GTT]

Originally posted by GTS-t VSPEC

With anything more than 14psi then I would suggest forged pistons, I have a set of Wiseco's going into mine. With the pistons being done I am also porting the head, balance crank, shot piening rods. the pistons will also lower the compression.

my 2c.

See'ya:burnout:

How much would something of this calibre set me back? with the forged pistons and porting will that then make the engine equivalent to a 2.6 litre?

[meggala]

my opinion is unless you want more than 300 rwkw youshould just fit a thicker head gasket or if you need to replace pistons then fit gtr pistons lower compression only $700 or so brand new

(pistons only) these can handel 1.3 bar or so

an power fc would be an advantage

whatshisname makes 250 rwkw on stock internals

meggala

[GTS-t VSPEC]

25GTT,

The main thing that will kill pistons is the boost, if you keep to boost low at 14psi then you should have no worries, as Megs pointed out you can make very good power on stock internals. The t3/t4 is a very good turbo and will easily get you over the 300rwhp mark, but it starts making serious power past 14psi, so if your going to push it them get the forgies.

The Wiseco pistons will cost about $1300-$1400 with rings. The cylinder is only bored an extra 0.5mm to get the compression down to 8.5:1. Porting of the head will not effect capcaity.

See'ya:burnout:

[MIKGTR]

Originally posted by GTS-t VSPEC

25GTT,

The cylinder is only bored an extra 0.5mm to get the compression down to 8.5:1. Porting of the head will not effect capcaity.

See'ya:burnout:

Boring a cylinder usually raises comp not lowers it!

unless of cause you leave the same pistons in there:bahaha:

[GTS-t VSPEC]

I think it is the shape of the pistons that has the effect on the compression, the pistons are 0.5mm larger than stock hence the need for boring, there are other compression pistons available but the 8.5:1 are usually considered the best option.

See'ya:burnout:

[MIKGTR]

yeah, I was half joking......

piston design(dome,dish,cutaways), deck height & cyl head cc are the main contributors to changing compression ratio

see ya

[sidewaymambo]

Originally posted by GTS-t VSPEC

.......the pistons are 0.5mm larger than stock hence the need for boring.......

sorry about this question, why the size is large then stock? From I read from meg's (thanks meg !) website that standard bore size is 86, does it mean, need to re-bore before change forgie pistons? or someone make 86mm pistons?

I saw some tomei forgie for RB25DET..it's 87mm..does mean my engine need to bore to 87mm? thanks..

[GTS-t VSPEC]

sidewaymambo,

Yes your right, they cylinder sleeves will need to be bored slightly to fit these pistons. Piston design is quite complicated, with quench area etc, being calculated. There are pistons that don't need boring etc, but they will most likely leave you will a higher compression.

Boring the cylinders is actually quite cheap with $20-30 per cylinder about normal, or a couple slabs of beer if you have a mate.

See'ya:burnout:

[sidewaymambo]

Originally posted by GTS-t VSPEC

sidewaymambo,

Yes your right, they cylinder sleeves will need to be bored slightly to fit these pistons. Piston design is quite complicated, with quench area etc, being calculated. There are pistons that don't need boring etc, but they will most likely leave you will a higher compression.

Boring the cylinders is actually quite cheap with $20-30 per cylinder about normal, or a couple slabs of beer if you have a mate.

See'ya:burnout:

Thanks mate..