Andy.F

I read a thread some time ago which gave cam lift and duration data. As far as I can remember, there were a few different lifts/profiles and changes through the years.
Early wrx/uk. Late uk/wrx. Sti early and Sti 5 onwards to name some.

Anyone know if there is any advantage to be gained from fitting the later cams to an early type engine ? Also what is involved other than the cams ? ie are Sti's still running hydraulic followers ? Different springs ?

I know where there is a broken Sti5 engine and was wondering what I could do with some of the bits

Andy

Pavlo

I spoke to Graham at Midland impreza at donny. I was talking about getting parts to put impreza heads on my legacy, he said the Sti II heads have solid tappets.

ALso I see collins performance do some cams, one of note is the high lift, short overlap rally cams. They have 0.4" lift I think, and require solid tappets.

As for the other cams out there i have no idea.

Paul

ustolemyname??stevieturbo

iTrader: (1)

Sti's seem to use solid lifters, with shim adjustment, as do later model UK cars ( guess at 98 on ). These cams would not be interchangeable with hydraulic cams. Also, if changing cams only, then all the valve clearances ( cam-lifter clearance ) would have to be adjusted using shims on solid lifter engines. Stuff that, it would be handier just to get the complete heads from a breakers. Also, the journals/oil seal diameters of various camshafts fitted can vary, so you would need to select very carefully if attempting to use cams from another engine.
No legacy camshafts are interchangeable with impreza's The head design is completely different.
Any engines I have taken apart, all have single springs fittted. They dont really need heavy springs to achieve the rpm's, coz the valves are so skinny and light.

Pavlo

I was considering alternative cams on alternative heads for my legacy. The prices I gave a while ago (£120+vat ea) were for rebuilt heads, all ready to bolt on.

Paul

submannz

Some years also use larger buckets to allow for the extra lobe height, so if you don't match the head then you are not going to achieve what you want.

WRX 1996-1997 solid lifter small bucket.
WRX 1998 solid lifter large bucket.

Get this EJ25 1997-1998 large bucket solid lifter, same head as the 1998 WRX head with same flow characteristics once slightly modified. Only need to bore out the inlet ports to match the block and convert the shims from overhead to on valve.

The reason I mentioned this is the EJ25 head is much easier to get hold of and much cheaper to buy from a wrecker, because the wrecker thinks WRX and puts the price up, doesn't realise the EJ25 head is almost as good as.

Adam M

up to version 2 use hydraulic lifters.

versions 3 to 6 use solid lifters with underbucket shims.

cant remember version 7 its either hydraulic again or solid with overbucket shims.

I do remember that the sti 3 has the most desirable heads as they are the most aggressive standard cam profile.

I would not want to be changing bit by bit. Much better to just buy a complete new set of sti heads.

which is damn hard to do, but pat has some sti heads iirc.

Adam M

ej25 are no good for phase 2 engine owners as they use SOHC.

you can fit phase 1 heads on a phase 2 block, but if you have a phase 2 manifold you will either need to adapt this, or switch it for a phase 1 and this screw up things like idle which is stepper motor controlled in the phase 2.

ustolemyname??stevieturbo

iTrader: (1)

I think it would be tricky to adapt the phase 2 manifold to the early heads, as the inlet shape is a bit different, as are the bolt spacings. Would it really be worth it?

Pavlo

Can someone confirm if there is a phase one engine with solid lifters? I've seen so many combinations, years, sti versions I've completely lost track.

In short, best overall option to replace the legacy heads with:

Paul

Adam M

yes,

version 3 and 4 stis have solid lifters as stated above.

Pavlo

My legacy has the old style manifold and 90' entry turbo. Will the STI 3 and 4 heads be compatible, as I don't want to replace inlet manifold etc etc etc.

Paul

ustolemyname??stevieturbo

iTrader: (1)

Pavlo. The UK legacy pistons do have a smaller dish, and fitting impreza heads will raise the CR.
I did strip a Legacy RS ( Jap spec ) a while ago, and from memory, the pistons looked like the wrx ones, but cannot confirm.
If you change the heads, you really shoudl change the pistons to match.
I put impreza heads onto my UK legacy short motor a while ago, and was getting detonation using 14psi, above 6000rpm.

DGRALLYING

Steve

So, do i take it from your last comment that the Legacy RS pistons are the same as the WRX?????

As i have both a RS and UK Legacy.

DGRALLYING

So will the STI4 Pistons fit in the Legacy Block?

and do you know if there is any difference between the rods?

ustolemyname??stevieturbo

iTrader: (1)

I cant remember for sure, but the pistons from the legacy RS were not the same as those in my UK legacy. They did visually appear the same as wrx in crown design. We did not remove them from the block tho.

1992 UK legacy piston-cast



1994 WRX piston-cast



1998?? STI V4 piiston, forged ( the clean bits around the edges, are from the piston hitting the cylinder head...big ends went...





And from Left to right ( bad picture )
Uk legacy, WRX, STI4



I'll try and find the RS engine and check them. But legacy cylinder heads are totally different designs, and the cams are not interchangeable. I posted pics of the 2 heads somewhere else for viewing.


[Edited by ustolemyname??stevieturbo - 7/9/2002 8:52:45 PM]

ustolemyname??stevieturbo

iTrader: (1)

I AM using STI4 pistons in my legacy block, but I am using MY94 WRX heads, They will fit. The legacy block, is the same EJ20G as in early impreza's/WRX's, closed deck, with oil squirters. However, due to differences in combustion chamber/piston dish, using pistons to match the heads is adviseable otherwise you will mess up the CR.
Legacy pistons + Impreza heads = higher CR
Impreza pistons + impreza heads = std CR 8.0:1
Legacy pistons + legacy heads = std CR 8.0:1
Impreza pistons + legacy heads = lower CR
I dont have any measurements to calculate how much lower or higher

The rods all look exactly the same, so id guess that they are.


[Edited by ustolemyname??stevieturbo - 7/10/2002 12:46:45 AM]

submannz

EJ25 Outbacks and Forresters use Quad Cam heads not SOHC. It is mainly the American EJ25's that are SOHC.

Yes the WRX Version 3 Heads, are the large bucket heads. They are the most desirable but very hard to get hold of, and supply and demand makes them VERY expensive.

Verison 4-5 still use solid lifter, but use small buckets - less cam profile.

Version 3 Heads $4,000 NZ Dollars,
Version 4-5 Heads $3,000 NZ Dollars.
EJ25 Quad Cam Heads $1,000 NZ Dollars, with mods mentioned above in my previous mail $1,400 NZ Dollars.

[Edited by submannz - 7/10/2002 10:50:32 PM]