Member profile - Chook

[dr20t]

You really should've swapped the whole box in

Straight fit with diff

[chook]

You really should've swapped the whole box in

Straight fit with diff

Ow I know that now, but I'm just a sucker for punishment haha

[rooby]

Sorry to hear it.

Manual time yet?

[chook]

Sorry to hear it.

Manual time yet?

Haha no manual, fortunately I have all the parts to fix it already and I have grown to love my auto despite all the grief, maybe one day Santa will bring me a full 6 speed manual conversion with the strongest box known to man!

[frank_ster]

what are the two black hoses that run over the alternator and then to the fire wall for ?

[kiahatsiu]

Catch can.

[chook]

Yeah they are for the oil catch can, they were originally transparent wire reinforced rubber hose but looked a bit shitty after the oil discolored the insides, replaced with a high temp black rubber hose.

[jacks-GTB]

I love the 2.5 block with 2.0 heads.....great combo with the DUAL AVCS

[chook]

I love the 2.5 block with 2.0 heads.....great combo with the DUAL AVCS

Heck yes it is in fact it completely eliminated the turbo lag with the extra torque.

what are the two black hoses that run over the alternator and then to the fire wall for ?

Now the top mounts gone I might redirect them behind the intake mani kinda looks a bit shit as is.

[dr20t]

Well done Chook. Look forward to the updates soon

In terms of ej20y heads on 2.5 block - look to get your head combustion chambers cnc'd to suit the 255/257 block.

This will allow better quench area and more timing with less detonation prone chamber

Mick

[jacks-GTB]

Well done Chook. Look forward to the updates soon

In terms of ej20y heads on 2.5 block - look to get your head combustion chambers cnc'd to suit the 255/257 block.

This will allow better quench area and more timing with less detonation prone chamber

Mick

X2 good call mick

[dr20t]

They always are Jackson - they always are....

[jacks-GTB]

They always are Jackson - they always are....

Hahahaha....o mick you make me laugh

[chook]

What is this magic you speak of Mick? My old workshop has a 4axis CNC mill in the Machining end what is involved?

[dr20t]

What is this magic you speak of Mick? My old workshop has a 4axis CNC mill in the Machining end what is involved?

Ooooowwww that's interesting

The ej20 motors have a 92.5mm bore. The ej255/257's have a 99.5mm bore

When you put ej20 heads on a ej255/257 block, there is a mismatch in the combustion chamber

When I was going to build my 2.5 block i was going to get the heads machined out to suit the 99.5mm bore. Otherwise the edge of the combustion chamber on the heads will protrude into the cylinder on the block and give you a rough edge and promote potential detonation. This means you are limited to the amount of timing you run.

It also bumps up your dynamic compression ratio as your compressed air / fuel mixture has less room to be compressed within. This can lead to preignition or limit the amount f timing you can run

The machining allows precise cc'ing of the head to get the right compression ratio and also smoothenes out the chamber so you havea cleaner burn. (No Jerome not the type you get when you urinate)

Another thing is engine builders often run thicker head gaskets to compensate for the increase in compression ratio causd by 2.0 heads on 2.5 block. This is not ideal and in high boost conditions can cause fatigue. This is an old school method of decreasing static compression. It works but is not the best option. Think weakest link syndrome...

The machining increases the combustion chamber and thus your compression ratio so it allows you to run an oem thickness headgaskets to reduce the chance of detonation and blow out

You will need someone pretty good to write cad for the 4 axis to get the chambers equal across all cylinders

Tony if you're reading this maybe you can help???

Mick