Everyone I have spoken to says differently. Knowledgeable people have said anything from they think they are basically identical, others suggest major differences. Anyone stripped both and can say categorically?

Sti, well mine anyway, have under bucket shims/followers. Certainly the sti 4 heads had sodium filled valves on the exhaust, I'm pretty sure the phase 2 ones do too.

The cams seem to have the same lift, so not much gain there.

However, some P2 sti heads have had the over bucket shims, which is the same as the UK heads.

Paul

I have seen an STI MY00, and it had overbucket shims. Visually it appeared identical to a UK MY00 but cannot comment on any cam profile differences.
Valve sizes etc were the same as we were replacing the some of bent STI ones with the not bent UK ones.

anything to add people, gathering onfo:D

Rob

Me to....

Say for example I wanted to run some bigger cams in phase 2 heads,

say 264 or 272 degrees with a fair bit of lift, 10 - 11mm..

UK run over bucket shims?

Can I not just machine up 32 new buckets that dont need shims??

Or am I being silly?

David

You can machine up 32 if you like, but I would probably stop at 16.

Or if you're even lazier you can buy them, you can also buy them with integral shims, so you just have a follower sized to give correct cam clearance, with no shim (like US 2.5 sti, maybe all 03 cars)

Paul

Why did I get 32 in my head???

Must be thinking of my valve springs.. Doh.

David

Yes you can "just" machine 16. What metal are you using and what are you machining them on, they are fairly well tied up when it comes to surface finish and dimensional tolerances.

well I wouldnt consider machining them up on the lathe in my garage.

David

In answer to my original post, the duration of the STi cams is longer, didn't find any data on lift for the non-STi. STi 5 and 6 exhaust valves are sodium filled.

My EJ20 was pretty much limited by the exhaust manifold and/or the cams. For my new engine I have changed both the manifold and the heads.

Due you have figures for duration for STI5 or uk 99?

I had some figures for duration for 99 UK, but can't now find them. I'll post the STi5 in a mo...

From memory... STi 5 242 intake 248 exhaust
Think the new age WRX is about 2 less on the intake and 8 less on the exhaust. Can't find the thread where I collated some of it all.

Thanks John, any info at all on lift for any of the above?

Wish I could find my old thread on it...

STi 5

Intake: lobe height 45.4mm, opening 9 BTDC - 53 ABDC
Exhaust: lobe height 45.65mm, opening 58 BBDC - 10 ATDC
Base circle: ?

US STi
Intake: lobe height 46.6mm, opening (15BTDC to 5ATDC) - (45 to 65 ABDC)
Exhaust: lobe height 46.8mm, opening 55 BBDC - 5 ATDC
Base circle: 37.0mm

UK STi
Intake: lobe height 45.3mm, opening (29BTDC to 6ATDC) - (33 to 68ABDC)
Exhaust: lobe height 45.65mm, opening 58 BBDC - 10 ATDC
Base circle: 37.0mm

US 2002 WRX
Intake: lobe height 46.3mm, opening 10 BTDC - 50 ABDC
Exhaust: lobe height 46.2mm, opening 53 BBDC - 7 ATDC
Base circle: 37.0mm

Some info on NASIOC:
http://forums.nasioc.com/forums/show...light=cams+sti

I am assuming that STi 5 base circle is also 37cm but you never know. Info is from various extracts from workshop manuals, so should be reliable.

[Edited by john banks - 11/16/2003 10:51:34 PM]

John,

If you take a look here: http://forums.nasioc.com/forums/showthread.php?s=&threadid=423564&perpage=25&highl ight=head&pagenumber=3

Someone has a STi V6 (RA?) engine with big port heads, definetly bigger than the Euro ports!

However I also found some flow bench values from the "small" port heads and they are absolutely not bad when compared to other cars. (eg. EVO) That test caused that I will keep the small port heads on the 2.5! I don´t think it will make a big difference as I don´t want to make much more than 360 - 370 BHP.

Why not porting the standard heads in stead of looking for expensive other solutions?

Mark.

I had some STi 5 heads ported since I posted this, and that is what is on my 2.5 in the car. Would be nice to work out what I have, I made assumptions from P1 cam data I had. It sounds like the cams are the limiting factor more than the heads?

I am confused by all the conflicting info!

There remains a question as to why people are struggling for over 400 BHP on stock STI 7 heads/cams despite competent turbos.

I thought my UK engine really struggled to get 400 BHP on standard cams, but I also had the standard ported manifold at the time, maybe that was the limit?

I take some heart from Bob and Harvey's results on unported STi 5/6 heads and standard cams, which mainly influenced my choice for my present project.

I am finding it difficult how to rank the following into power potential:

STi 5/6 (presumably R/RA are the same since they use same ECUs)
STi 7 UK
STi 8 UK
STi 7 JDM
STi 8 JDM
STi RA Spec C
USDM STI
US WRX
UK WRX

Unfortunately we are left with incomplete data, and then have to work out how much lift compensates for duration, also availability of donor heads/cams would be nice to know.

So which are the golden trophy head/cams for bolt on heads for Phase II engines with big ambitions?

John,

I wouldn´t use STi cams, as they are made to produce good power over 7000 RPM. Most of them (at least the post MY00 ones) don´t have too much lift and long duration. I think the US STi cams aren´t too bad for use in a 2.5l engine as they have quite some lift and not too long duration. (that are the ones I am going to use though!)

Mark.

Bob and Harvey's 2 litre cars both make peak power around 6500 RPM +- the last I heard though... so I am thinking that same heads/cams in my EJ257 should not be too bad with a 7000-7200 limiter? Perhaps I don't really want the RA Spec C heads though since they would be wasted on a 7000 RPM limited motor? Tell me I've done one thing right on this project please :)

I read in a post a while ago, andy liked his duration, just would like more lift..

David

Presumably changing the boost level can shift the peak power point to coincide with best cam performance?

A terrible situation would be a 2.5 with such mild cams that you end up with the same power as the 2.0 just at lower RPM?

Peak power at 5500 RPM instead of 6800 RPM could completely obliterate the power gains of a 2.5? Then the guy with the short geared 8000 RPM rev limit Spec C engine could keep up without bother!

Interesting results from sponaugle with STi RA Spec C heads and 2.5.

Interesting and confusing. A bit like M3 vs M5.. the smaller engine with 100 lbft less torque in only a slightly lighter body but with higher rev limit and shorter gearing is basically as quick in gear! You could easily have a situation where a lightweight classic with the right breathing/cams (Andy F?) could obliterate an apparently trick 2.5 bugeyed? I am sure he would love that :D

[Edited by john banks - 11/17/2003 9:41:15 PM]

John,

I saw dyno's from the US STi with big turbo and peak power @ rev limiter! So I don't think these cams are too bad, for a 7200 RPM redline engine. I think you will loose too much low down with non VVT heads and high duration cams. It's personal but I want as much torque as low as possible in the rev range and about 340 lb/ft and 360 - 370 HP. I try to achieve this by using: US STi short block, Eurospec STi8 heads with VVT, US STi cams, PE1825 with OEM Twin Scroll manifold, 650 cc injectors and Motec M800 ECU, custom made FMIC and throttle housing in front of the manifold. (should be nice!)

P.S. It can take some time as I have to do it in the time I am not working.......

Mark.

Sounds very nice, should give some evil low down torque :D

If you are hooking up the M800 you must have a pretty good idea of how to control the AVCS. Do you have any information on this you can share? Is it a closed loop control duty cycle?

[Edited by john banks - 11/17/2003 10:37:38 PM]

Yes, Twin Scroll OEM manifold!

I have the ECU and the software to enable VVT control but I didn't install it yet and I have no idea how it should be mapped. (yet!)

Mark.

What cams are Bob and Harvey using?

Standard STi 5 for Bob and STi 6 for Harvey as far as I know, I'm sure they will correct if wrong. Imitation is flattery gents :D

I am running standard STi 6 heads and cams and there has been no head work whatsoever.
Bob is similar though he may have cleaned up his heads...not sure.
AFAIK the head castings for phase 2 are the same but STi valves are different as is the bucket/shim arrangement.
I have a set of STi5 cams for sale which are same as STi6. Also for sale are two STi bare heads and one R.H. bear head with a damaged exhaust seat.
Max power of 533bhp is at 6,900rpm with torque of 420ftlbs aroung 6,300rpm.

I have alredy re-worked the heads to go on the new engine which has Jun cams and recon there will be good gains over the existing set-up.

what duration and lift harvey? If you dont mind me asking? :) (off line if you dont want it on here)