EJ20x/y Heads (Quad Avcs) Specs?

[DacerX]

Is anyone using these heads in a non legacy application or upgraded the valve train in them (2004-Legacy turbo heads)?

I'm trying to find valves, springs, cams, retainers for them but the internet is big and information is small. The aussies seem to just be boosting the factory motors to the max with re-flashed ecus and not changing anything and then hitting issues at around the 250kw mark. Im doing a forged bottom end with these heads but finding stronger components or finding information about if they are interchangeable with V11 is non existent. At the moment it looks like everything is custom unless i can get sizing from V11 sti heads which done just sit on peoples shelves.

[Guest]

You would have better luck on 22b. One of the smarts over there was saying some are really limited others not but didnt know casting numbers.

[Kiwi_Fozze]

Problem with the twin avcs heads, particularly the v11 sti ones is they tend to crap themselves with too much timing advance, dont take the abuse nearly as well as the earlier model heads

[Guest]

Biggest gains are in the intake cam anyway the benefit of floating ex cam are minimal.

[Kiwi_Fozze]

Good for emissions control i understand....

[Andy_Mac]

Guy on liberty.asn.au rocking a crazy 400kw with grb quads. Was originally a x/y but was swapped out for a 207. Is onto it with the tuning side aswell and is pretty good answering peoples obscure questions too

[DacerX]

I know the guy and have been in contact, and have now all the info i need. also know his tuner in sydney as well. This wasnt that best place to post

Edited May 4, 2015 by DacerX

[Guest]

 DacerX said:

I know the guy and have been in contact, and have now all the info i need. also know his tuner in sydney as well. This wasnt that best place to post

So now you know keen to share?

[DacerX]

i will if anything if anyone is interested, but so far no ones been that interested in this kinda thing

[Guest]

People are and questions been asked a few times on here i even asked on 22b on behalf a while ago but like i said the guy wasnt sure on castings. I considered grabbing some instead of v6 sti heads when i first built my engine but due to no info flagged it.

[DacerX]

OK then

So first if you are wanting to go Quad AVCS you have 2 options. Legacy 2004- turbo or V11 STI- and thats it.

So second why go to Quad AVCS over V7 dual AVCS?

Well, basically the overlap is the major difference.

Dual AVCS allows for 40 degrees of advance on the Intake. Which gives a total variable overlap of 0 to 40 degrees.

Quad AVCS allows only 30 degrees on Intake, to combine with 40 degrees of exhaust retard. Combined the two allows for a total overlap of -17 degrees (no overlap) to 53 degree of overlap. Not only do you get more overlap, but for a given overlap you also have the ability to move the overall cam timing.

In simple terms it increases low down torque and quicker spool. This is one of the main reasons why the LGT and the V11 feel very responsive. And why subaru are now using this type of design on the new FA and FB and the EZ30 have it, because it works and is good.

So now to the technical information:

So in the legacys there are 2 types of heads that i have been able to find that have different casting marks on them, U20 and W20. The size of the ports is slightly different with the W20 being bigger but being micro compared to V11 heads.

Now some parts are interchangable such as cams, springs and retainers. But the one thing that is not is valves, sadly at this stage no one makes aftermarket valves for LGT heads and this is one of the main reasons more Legacy owners in Australia are going to V11 over working on the LGT heads that they have on the stock engine as well as going to a later EJ207 if they get a complete engine. The later EJ207 is amazing and can handle alot more power than EJ engines of the old days.

So why use LGT heads at all? Well because of the supply of legacys that we have in this country is huge and they are being wreaked all the time as well as engines blow and what most people do is get a new longblock so heads are available.

So for legacy owners this is good news if you wanting to get more power out of your car. just need to get STI cams from a V11.

So if you have a legacy your ecu should be able to be adjusted for these upgrades, or you need a Link/Vipec/Haltech.

So to recap. Yes LGT heads can have interchangable parts with V11. Porting of LGT heads is a must if you are doing this. V11 valves are not the same. There are a few different cams so measure what you have.

I will be putting more info when my parts come and i start building them as parts arrive.

[Guest]

Mean. Open up a new thread will add it to the sticky restructure.