R33 Rb30 Conversion

[Cubes]

It does mark Mark thanx for your input.

My pistons are Wiseco also. When cold it sounds much much quieter than the CA18 when warm and can only 'just' be heard to the point where it makes you think is that slap or is it top end noise. Once warm there is zero noise from the motor.

The CA18 when idling after around 3-4hours on the dyno had a rather loud slap that could be easily heard when standing 10meters away. I was actually quite concerned with the noise to be honest.

[the phantom]

Hey mark99,

Interesting how you bring that up. The first thing I noticed with my Arias' was the obvious difference in skirt diameter to ring land diameter. It is so obvious that you can see it with the naked eye along a straight edge.

[Bl4cK32]

Thought id put up these...cant see much, but it shows the ones Joel and myelf used...

[Cubes]

Phantom,

Any chance of similar pics that can be taken of your Arias pistons?

[the phantom]

Phantom,

 

Any chance of similar pics that can be taken of your Arias pistons?

I'll do it tonight....

[mark99]

Phantom, yeah arias usually are not only a lot smaller on the top ring land but also the top land is usually fairly noticeably tapered toward the crown. From memory on an RB arias would be around .035" smaller on the top land and tapered. Where as wisecos are around .020" and parallel. Of all the other pistons ive looked at, JE, CP, Ross, SRP, Venolia, ACL, Speed Pro, etc, they've all stayed much closer to the .008" - .009" per inch of bore with varying from parallel to heavily tapered. Not saying Wiseco dont know what there doing, just that design seems perculiar to them. A good point is it protects the top ring a little more, a bad point is if combustion temps get a little high not a lot of room for expansion before the land will touch....

[the phantom]

Some photos of my Arias pistons. The last photo in particular highlights what mark99 was on about regarding the general reduced ringland area diameter, and the tapered upper ring land...

[ace_nz]

tapering like that is a cheap way to try and stop piston noise, it prevents the top land from slaping the bore when the piston rocks. Wisecos are a far superior product.

[Cubes]

Top stuff Phantom.

Did the pistons come with a little piece of paper or writing on the box that states the dome cc', compression/pin height etc?

The design at the top and dome height looks ver very similiar to my wiseco's.

What compression ratio are you hoping for?

[Alf]

The design and visual differences have been covered.

But what about the price and failures?

How much more are the wisecos and has anyone experienced failures with either brand of piston.

[Cubes]

My RB30DET pistons where $1200-$1300, some where in between.

Both pistons are just as good, it depends on what the engine builder is 'used' to building with.

Mine was comfortable with Wiseco's and said Wiseco's are a good piston, that is what he recommends.

No good building up a motor with pistons you are not familiar with as then you might get the horrid piston slap as per that CA18DET I saw.

The piston slap really was excessive I thought.

[the phantom]

Price of the Arias' was around $1320 delivered to your door from Rocket Industries.

The spec sheet does not mention dome volume, but I can measure that. Compression Height is stated as 32.512 mm (1.280"), and the lack of a star stamped under the pin boss indicates that they are 2618 non silicon alloy as opposed to 4032 high silicon alloy.

The compression ratio is not mentioned on the spec sheet however the sales man indicated that they are supposed to achieve around 8.5:1. I'd be happy with that, although I'll see what is in it during mock up.

[Cubes]

Keep us posted Phantom.

I'm going to be using this info for a build up that I will need next time around.

Next time around will have rods etc done as I will use the car for mostly track fun.

[Fitzpatrick Speed Works]

great post ace_nz full of well thought out facts!!!! I have the new high top Aries specifically made for rb26 heads with rb30 bottoms, will post pics tomorrow, the tappering doesnt look as severe. Yes it is designed to minimise damage to the piston but that doesnt mean its inferior, i have helped put together 6 gtr engines and countless rb30's all with aries and never had any noticable slap noise or any problems whatsoever.I had one failure using weiscos on a gtr the slap noise was noticable from the begining of the bore, the bore was scored and it started blowing smoke, but i am in no way saying this is a regular thing im sure it was a one off, trade price on the arias is $1230, and the Weiscos from memory where $1195 but that was a while ago

[Fitzpatrick Speed Works]

also during my mock up the arias sit above the deck height, as do most pistons with this set up but particularly because im using the eagle h-beam rods, however i countered this with a 1.6mm head gasket to achieve an overall CR of 8.35:1.

[the phantom]

Hey s13drifter,

I thought it was only me left somewhat perplexed with ace_nz's comments

Are your Arias' 2618 alloy or 4032 ? What piston/bore clearance was run in the engines you were involved with?

[Cubes]

s13drifter,

when you say

the slap noise was noticable from the begining of the bore

what exactly do you mean?

[Fitzpatrick Speed Works]

sorry joel mate that was a typo i meant to say from the start of the run in, i got ahead of myself!

Im running the 4032 in mine but i havent ever really noticed a difference to tell you the truth, you could possibly run a tighter clearence with the other 2618 or whatever? due to lower silicon content but it would be that close i dont think it will matter. all the builds i have been involved we have set the clearence to 0.0035" clearence on every rb series engine.

other engines vary like an sr is run at 0.0045" and ej20 we run alot tighter, due to the closer clearances set by the maunufacturer when they are stock, and you do notice a more audabile knock on start up due to this. you can always hear a knock in wrx's when its cold when its fitted with forgies! i guess this shows you can get a knock from forgies going either way, either with piston slap due to bigger clearences or from going tighter!

Never be scared of a little noise from forgies, you guys should hear what some of the big block chevs sound like with them, massive pistons size with big clearences due to higher afrs to extract power from na's, they are pretty damn loud on start up but they settle in!!

[the phantom]

Thanks for the info s13drifter!

The 4032's being the higher silicon content than the 2618 is supposed to be able to run tighter but your right...who knows...without building lots of them and then pulling them down.

Just a few more questions!!.....

I take it you have the chrome rings with your Arias'. What bore hone crosshatch/pattern/machine did you see used with the RB's and what kind of running in did you see done....immediate high load, or gently? Apologies if this is changing the topic.

[discopotato03]

S13 Drifter , are there any more details on those 26/30 pistons . Is it possible to run the normal head gasket (for high 8's CR) or do valve clearence and quench issues arise . Also what bore size are these and what kind of rings are supplied .

Thanks A .