Help needed as usual

looking at a 2.5 conversion short block into my Bugeye...... Hopefully the mods already in place can cope but wondering about the "black art" of heads ??

Can I just use my Bugeye WRX heads or do I need something different ??

There are some heads on here which seem to have been ported for the 2.5 ..

https://www.scoobynet.com/private-fo...for-2-5-a.html

Cheers


Shaun

 

I'm going the 2.5 route with my bugeye wagon. The block I bought came with the above heads on it. They're not suitable for use with newage convesion, hence why I'm selling them. I'm getting my own wrx heads chambered to suit the 2.5 block and fully ported too. My goals are 450 mark. I'm not sure of why the STi V2 heads are not suitable, but I'm sure someone else will be able to shed some light on the matter? Hope this helps, at least a little?

Ryan

 

The V2 heads are not compatable with the newage due to a different bolt pattern for the inlet manifold afaik.

They will be good heads if Steve Whitson did the work!

 

Exactly! I've been trying to sell these heads for ages without any luck at all. Was advised to advertise them at double what I'm asking for them by the man himself. Then halfed the price and still no takers. The work on these or any others being made to the same spec would be £500 for labour alone!

Ryan

 

Hmm......just wondering what might happen if my MY 02 Bugeye WRX heads are bolted to a STi 2.5 block !!

I assume the CR will increase amomng other things ?

Where's Paul Blamire, Alan Jeffrey, David (API).........and the rest when you need them LOL

Shaun

 

Shaun,
The CR will also be dependent on what pistons you choose (dish volume) and how much is skimmed from the blocks.

A decent block builder will work out the TDC volume for the block, then there is the head and HG volumes to feed into the CR calculation.

There is a bit of help here with various volumes:

http://forums.nasioc.com/forums/show....php?t=1667168

Nick

 

I'm going for the ej257, with my 2002 wrx heads bolted on top. You need the chamber cc's adjusted to match the 2.5 and porting to aid flow. I'm guessing the 2 litre heads would go straight on, but would be a waste of time without above work done to them? I'm sure the wrx heads have tumblers that need removed to improve power also. Somone else should be a bit more accurate with information on this than me.

Ryan

 

I'm going for the ej257, with my 2002 wrx heads bolted on top. You need the chamber cc's adjusted to match the 2.5 and porting to aid flow. I'm guessing the 2 litre heads would go straight on, but would be a waste of time without above work done to them? I'm sure the wrx heads have tumblers that need removed to improve power also. Somone else should be a bit more accurate with information on this than me.

Ryan

 

Could you not use the modified V2 STi heads with the matching inlet manifold ?

The newage manifold won't fit onto the earlier heads or vice versa because of the bolt pattern but any 2.0 heads bolt onto the 2.5 block.

What would stop you using an inlet manifold that matches (ie. V1-V4) and then dropping in the complete engine assembly ?

If all the bits from your newage manifold will fit onto the 'classic' manifold, you could buy these STi heads at a bargain price, all you need is a cheap manifold off ebay !

You do need to confirm with someone far more knowlegable than myself that your bits will fit the 'old style' manifold first however !

 

Thanks for all the advice........I'm going for some 2.5 AVCS heads if possible I have been told the the cams can be locked in a middle / neutral position so that low down and top end is "in the middle"

Shaun

 

What about version 5/6 STI heads Shaun? They should bolt straight on, or are you after very big power? Isn't your car about 400+bhp give or take?

 

Mike

If I buy 2.0 heads I'd stil have to have them altered as the cubic capacity of the bowl is all wrong and they would also be the wrong diameter.... I'm aiming for something simple

My car is about 400 at the moment, I Just wanted to "future proof" for the next few years as I'm going to keep the car until it falls apart LOL

Still enjoying wakey ??

Cheers


Shaun

 

Ahhhh I see, I'm thinking about big power 2.0-2.1s etc

Yeah I'm still enjoying living down here, just started a new job last month, I'm now a Caravan sales executive( posh title ). Have you settled into your new home? How's your family?

 

You ba***rd! Keep those bloody things off the road!


Hows it going Mike?

 

I think you will find that wether or not work should be done on 2ltr heads to make them fit better the 2.5 block is pretty much a split camp amongst the very few that appear to have a view upon the matter.
I asked the question of David Knights local to me here in Northampton who do purely head work and he pretty much said how on earth can I manage to do that properly.
API did my 2.5/WRX heads conversion and the subject of increasing the cc of the bowl was never discussed.
The 2.5/2ltr head is reliable and to do re-sizing I'm sure brings in risk and uncertainty.
The right turbo, at least equivalent MD321T or V, air flow into the engine and the ability to run safe higher boost are what I'd be looking for.
Trev

 

Haha! Yeah I'm good thanks loving putting more Caravans on the road how's things out west?

 

Hmmmm several comments come to mind here.

The original heads will work but are small port with nothing special for cams. They cannot flow enough air in standard form to cope with big turbo.

The better heads - without going down the Avecs route, would be STi 5 or 6, they bolt straight on and work well. I think as a comparison, we gained some 40 hp on a car that originally made 419 on the WRX heads with nothing else changed. You would need STi 5 cam wheels to match the heads as the trigger points on the Avecs pulleys are in the wrong place.

Avecs cams are designed to do their job as Avecs and no matter how you statically time them, the result will be compromised.

Wiring in the Avecs is time consuming and not for the faint hearted.

Fitting Version 4 backwards manifolds and heads to a Vers 5 on type engine is also a fraught-with-pitfalls job, as all of the senders and electronics are wired differently with differing connectors. It can be done - but is best avoided.

David APi

 

I understood that AVCS cams have the same duration as WRX cams but with more lift, so I don't understand what compromise there is if not activated by the trick cam wheels?

Installing STi AVCS heads but with the solenoids not connected, the oil ports on EX cams sealed up and reusing the WRX cam wheels and position pick up sees to be a proven method in the US.
Some even put AVCS cams into WRX heads, again with the oil ports sealed up.

 

I think it must be the cam lobe shape, as opposed to duration or lift, as they worked OK on the one that I have in mind but just didn't perform like we'd hoped. We fitted STi5 cams and wheels and it was instantly transformed. Once we had proved that we could make it go, we didn't bother with an inquest on why it hadn't worked on Avecs.

We had found something that did work without any fuss.

David

PS I don't take any notice or heed of what the yanks do. In my experience the result is often a compromise, which after all the work they have done to make it happen is not good enough in a professional advice perspective.

I adopted that stance after a situation many years ago when one of them came on here about rewiring a car to make a US wrx into a JDM Sti or something similar. And it went to several pages about stripping out the original wiring loom and separating all [ ALL ] the wires and identifying this and identifyting that and join reds to green whites etc., etc., _ you get the drift ??

 

Good mate ta. How long you been in tight wad country?

 

David...... I'm not after big power

If I can't find any STi ver 5/6 heads can I just bolt on my Bugeye WRX heads and at least get the car up and running ?

Cheers


Shaun

PS would these heads bolt on and be OK with a newage manifold ?

https://www.scoobynet.com/private-fo...-complete.html

 

They'll do better than what you have now. Buy em Try to find some STi 5 or 6 cams and you're sorted.

David

PS yes you can go with what you've got now, but they don't flow much air due to the small porting and it will be disappointing.

 

Hi David

Thanks for that Do you have any suitable heads floating around your shelves ??

Cheers

Shaun

 

I'll be too expensive for you, as we have them ready prepared, built up and so on. Why not buy the Ebay ones?, there is virtually no difference for the head castings and they all have cracks around the plug holes anyway. [ which you ignore, unless you can fall in them ]

David

 

Ye got anymore info info on locking the 2.5 cams???

 

I've been down here nearly a year now

 

Mike

Do you have anything to do with "Beverly Caravans"........ my dad worked for them in hul for many years

Shaun

PS David, what do you mean by "Expensive" ?

 

You can run the 2.0 hears as long as you run the thicker head gasket, the CR will still be higher than the factory 2.5 style heads, but will be manageable for a good tuner. You other option is to have the combustion chambers ont eh heads opened up to correct the CR and get the heads to match the larger cylinder bore. If you are goign that far some port work will be easy to do at the same time. as for cams the STI cams from a US 2.5 STI are a botl in to the 2.0 heads if you block the AVCS oil passages on them.

We just did a 2.5 block on my wife's car (was a 2 liter) she ported the heads, match the combustion chamber, and installed some 06 up 2.5STI cams (they are hollow so les mass in the valve train)

 

You can run the 2.0 hears as long as you run the thicker head gasket, the CR will still be higher than the factory 2.5 style heads, but will be manageable for a good tuner. You other option is to have the combustion chambers ont eh heads opened up to correct the CR and get the heads to match the larger cylinder bore. If you are goign that far some port work will be easy to do at the same time. as for cams the STI cams from a US 2.5 STI are a botl in to the 2.0 heads if you block the AVCS oil passages on them.

We just did a 2.5 block on my wife's car (was a 2 liter) she ported the heads, match the combustion chamber, and installed some 06 up 2.5STI cams (they are hollow so les mass in the valve train)

 

SportyMark

Is Apex in North Carolina ?? I worked here for a while in the Early 90's LOL

http://www.dent.unc.edu/

Shaun