Forged pistons?

[Adam.Findlay]

as noted by @zentac he failed the crank at around 600hp he also used JE pistons cant remember what rods he used though. crower or carillo rings a bell

[Gly]

Yeah keen for what ever you guys can sort,

Out of interest what turbos are you thinking about using on your setups.

Also later in the year ill be poping into hytech to see what they can do/recommended and offer in regards rebuilding the engine

[Kenneth]

I am keen on either high compression or high boost. I don't mind stock compression ratio, but the pistons need to be up to handling >30psi (potentially 50psi) of boost. From my understanding, this means avoiding pistons with a high silicon content.

If they are well priced, I will compromise though

[scott.mohekey]

I'm after 30ish pounds of boost, like Kenneth. Given that the stock pistons can supposedly handle quite a bit, I'd hope that the wiseco ones should be good for anything we can throw at them. I could contact IPP and ask about silicon content if that would help?

[Adam.Findlay]

kenneth what would you think about a 9.0:1 CR that can still withstand those huge boost levels.

[Kenneth]

I'm after 30ish pounds of boost, like Kenneth. Given that the stock pistons can supposedly handle quite a bit, I'd hope that the wiseco ones should be good for anything we can throw at them. I could contact IPP and ask about silicon content if that would help?

Yes, would be great if you could clarify that with them.

kenneth what would you think about a 9.0:1 CR that can still withstand those huge boost levels.

Am happy with anything between 8.5:1 and 10.5:1

[scott.mohekey]

Just sent this off:

Hey, it looks like I won't be making it over to Canada now, but am
still very interested in getting a set of these.
In fact, I'm a member of a VR4 club that is interested in doing a
group buy if that would be possible? There are
currently around 5 or 6 people showing interest, and that may grow.

We have a few questions we'd like to throw at you as well:

What is the silicon content?
Are they set up for floating pin?

Thanks, I look forward to hearing from you.

[Kenneth]

Sounds good. Might have been easier to just ask what sort of boost level they are rated for though?

I realise my last post wasn't very helpful in that regard though, my apologies. If they respond with the silicon content, I have no idea how to tell if that is high or low.

To clarify, my understanding is that silicon is used to make the pistons more dimensionally stable (don't change size by as much) which means they are quieter on warm up but results in a more brittle piston.
Low silicone content results in the piston being liable to slap around a bit while warming up but results in a less brittle piston which is more durable when being hammered.

[scott.mohekey]

I thought about that, but its a bit of a subjective thing, and I figured they'd not want to quote any figures to save themselves from any sort of liability.

[SEAN-NZ]

some info found on wiki about silicon content


what i think are the most important parts on the page

By adding silicon to the piston's alloy, the piston expansion was dramatically reduced. This allowed engineers to specify a much tighter cold-fit between the piston and the cylinder liner. Silicon itself expands less than aluminum, but it also acts as an insulator to prevent the aluminium from absorbing as much of the operational heat as it otherwise would. Another benefit of adding silicon is that the piston becomes harder and is less susceptible to scuffing which can occur when a soft aluminium piston is cold-revved in a relatively dry cylinder on start-up or during abnormally high operating temperatures.
The biggest drawback of adding silicon to pistons is that the piston becomes more brittle as the ratio of silicon to aluminum is increased. This makes the piston more susceptible to cracking if the engine experiences pre-ignition or detonation.

The normal temperature of gasoline engine exhaust is approximately 650 °C (1,200 °F). This is also approximately the melting point of most aluminum alloys and it is only the constant influx of ambient air that prevents the piston from deforming and failing. Forced induction increases the operating temperatures while "under boost", and if the excess heat is added faster than engine can shed it, the elevated cylinder temperatures will cause the air and fuel mix to auto-ignite on the compression stroke before the spark event. This is one type of engine knocking that causes a sudden shockwave and pressure spike, which can result in an immediate and catastrophic failure of the piston and connecting rod.[citation needed]
The "4032" performance piston alloy has a silicon content of approximately 11%. This means that it expands less than a piston with no silicon, but since the silicon is fully alloyed on a molecular level (eutectic), the alloy is less brittle and more flexible than a stock hypereutectic "smog"[clarification needed] piston. These pistons can survive mild detonation with less damage than stock pistons.
The "2618" performance piston alloy has less than 2% silicon, and could be described as hypo (under) eutectic. This alloy is capable of experiencing the most detonation and abuse while suffering the least amount of damage. Pistons made of this alloy are also typically made thicker and heavier because of their most common applications in commercial diesel engines. Both because of the higher than normal temperatures that these pistons experience in their usual application, and the low-silicon content causing the extra heat-expansion, these pistons have their cylinders bored to a very loose cold-fit. This leads to a condition known as "piston slap" which is when the piston rocks in the cylinder and it causes an audible tapping noise that continues until the engine has warmed to operational temperatures. These engines should not be revved when cold, or excessive scuffing can occur.

to read the page in full
http://en.wikipedia.org/wikieutectic_piston

[scott.mohekey]

I got this response from IPP:

Pistons are Forged not silicon like cast.
Pistons can be used for floating or pressed.

It doesn't exactly fill me with confidence in them. They also completely glossed over the mention of a group buy. Maybe I should try contacting Wiseco directly?

[Adam.Findlay]

straight from the horses mouth is usually the best way. instead of getting halfasses answers from salesman who knoes bugger all about the product

[SEAN-NZ]

i would just ask what aluminium they use, if they use 4032 or 2618, that will let you know how much silicon they have, more is better for heat expansion, but less more overall strength as apparently the 2618 is about 17% stronger, so as far as i can see the forged do still have silicon in them, just depends on what is used

[Adam.Findlay]

for those after a cheap option today i talked to peter and hes compared pistons for us. 4agze pistons are the correct pin size, bore and deck height. also they are forged from factory. he said they can be obtained brand new for around the 150nzd per piston mark. or stupid cheap second hand.
they are floating pin type so will work with @swinks rods.
i can organise group buy on these pistons through peter (the guy who does the cam regrinds) whos keen?

[Adam.Findlay]

@Gly @Barney

and @Kenneth peter is also contacting cp for me he thinks it wilk be around 1300 for a custom set of pistons. will pm you when i get details. hes also getting in contact with auscrank about forged cranks the issues with harmonics and cost. will keep you informed

[SEAN-NZ]

how much power can the 4agze pistons take?

[scott.mohekey]

I've heard of some 4agte's getting 500hp on the stock pistons. So if you work that out as power per piston, it should be more than enough for any of our goals.

[Kenneth]

Am looking forward to hearing from you

Could be worth while looking at hayabusa pistons, the bore and pin size is correct for 00-07.

@Gly @Barney

and @Kenneth peter is also contacting cp for me he thinks it wilk be around 1300 for a custom set of pistons. will pm you when i get details. hes also getting in contact with auscrank about forged cranks the issues with harmonics and cost. will keep you informed

[Adam.Findlay]

will look into that too thanks for the info. i bet the hayabusa pistons would mess with the CR too much though.

[Oblivion]

Sounds like theres going to be some monster VR4's running around soon!