Absolute Shower

Anyone thought of using piper cams in heads with 2.5L conversion>??? Are they any good?

Has anyone had experience of modified oe cams and is the job decent in the long term?

Pavlo

They are good, but you will need to ensure the rest of your valvetrain is up to the job.

Absolute Shower

Excellent, sounds like I'm on. Which is better, Piper or Kent or both the same? I'd get the full kit to go with it, springs etc.

Pavlo

There isn't, or wasn't a full kit available when I got my cams. Depending on what heads you have you may need more work in terms of replacement followers and shims.

Absolute Shower

Okay cheers. I'll have to investigate more...this looks like my only option (although a good one I think) as you can't get hold of STi v5 cams anywhere!

Cheers again.

Adam M

personally I would buy a set of version 3 heads and don't waste your time and money sorting out the heads.

500+bhp can easily be made on standard heads, it is only if you are pushing boundaries that it is worth going the distance.

I would personally be concentrating on making sure the short block is up to the task.

Absolute Shower

Wow, is that right, I've got 02 WRX heads and with standard cams it will still be okay for 500bhp? I wont be going that high as I've not changed the internals - I want a very fast but reliable car and dont want to be changing the gearbox again in a few years time!

Isn't there running problems with the oe cams though...ie timing issues in the mid range?

P20SPD

iTrader: (1)

i wouldnt push that much on a set of wrx heads, i was laughed at by many, for pushing probably 400+ on my 2.5 with MY00 UK heads and Valvetrain, the valvetrain being the weak link.

I have a full complete set of sti3 heads and valvetrain available if you interested. I ended up having my MY00 heads ported and the cams sorted, so have no use for th V3 heads. PM me if your interested.

Steven

Pavlo

Sorry,

Adam is dreaming. 500hp can be made on standard sti heads, but not on UK wrx heads, not unless you really overspec the turbo. Version 3 heads will be no good to you as the inlet manifold is a different width and the stud pattern is different.

On the new age heads the lift is quite high, so your springs should be up to taking a relaively wild cam profile (in lift terms) with the standard springs. You can't go too far as the rampup and down will be too much for the springs to prevent bounce.

Your best off the shelf solution would be some phase 2 sti heads, if your can has AVCS then you shoud get a set of JDM sti heads if possible.

Paul

Adam M

paul, at what point when I wrote my post did it say he had a new shape car with UK wrx heads?

the version 3 heads I was referring to were the sti heads which have a profile fairly close to my own, ie. not too wild.

paul is right in that if you have that age of car the inlet manifold will not fit with some older heads, and changing the inlet manifold to the earlier type isn't likely to be a good solution on the basis that you idle speed is steeper motor controlled, so it makes things unnecessarily complicated.

I would still say stick with your own heads for now and see what they can do. I doubt very much you will be dissapointed with the performance they can produce.

The rev limit of the older heads (version 1 and 2) was due to the weight of the pistons not due to the supposed hydraulic lifters which they don't have. You will have solid lifters on your heads which given the right pistons in your short block can still happily rev to 7500 or 8k rpm. (I wouldnt bother personally).

You are with a decent turbo going to get a very nice power and torque figure from that, but you are talking £400 for reprofiled cams, plus rebuilding the heads, plus valve and spring work to account for greater raked profiles, plus potentially vernier pulleys, all for not a massive return and a higher idle speed and worse fuel economy.

At that point you are really into seriously diminishing returns, and all I can say is that I learned the hard way.

APIDavid

iTrader: (4)

Isn't there a problem with shim length on reprofiled cams? By achieving the lift the base circle of the cam lobe needs to be reduced to gain lift at the lobe side. Thus a large gap appears between the bucket and the new profile of the cam necessitating a much thicker shim?


David APi Engines / APi Impreza
www.apiengines.com

Tim W

iTrader: (1)

David with new or re-profiled cams you should ideally have new buckets as well so it's easy to compensate for the increase clearance with out compromising on shim thickness...when I had my Sti 4 cams reprofiled by Piper I also had new buckets and top hat shims made along with fitting new double springs...in the end I speant around 1600 quid on my heads geting them flowed, the combustion chambers opened out a bit, new guides etc...all fully built up the only orriginal parts left in the end were the valves and the base casting

Adam M

same here as tim.

This is another reason why I think it is in serious diminishing returns territory.

Most power with turbocharged engines comes via the turbo charging, they are less dependent on breathing mods. That is not to say that breathing mods don't help, but when you can easily an reliably run more boost, power can be achieved cheaply. If you are not chasing every bhp then it makes far more sense to use boost pressure and easier VE improving mods to make your power.

Pavlo

Yes David, but that's where a different style of retainer which will happily take the thicker shim comes in. On the STI 3/4 heads you can use top hat shims located on the valve. On my sti 5 heads the retainer is designed to accomodate a much thicker shim securely. If you had billet cams this extra should could easily be machined off of mine.

With the engines running shimless buckets you can change the retainers to allow shims. More than one way to skin a cat.

Paul

Absolute Shower

It all sounds very complicated...not sure if worth starting or not. Depends what spec I'll have the 2.5L block at...all up in the air at the moment.

So, if I did just do a cam reprofile, but not wild, the oe springs should be okay, just needs some shim work? Not too expensive?

Pavlo

pretty much, expect to pay around 200 to get a head reshimmed depending on how many shims you need.

Tone Loc

iTrader: (1)

Adam,

Can i ask where you got this info from? I assume you're talking STi here rather than UK/WRX???

Tony.

Mark A

iTrader: (1)

AS pm me the short motor cost, I have a US contact who might help you if the price is high.

Adam M

Tone, I wasn't talking about stis, I was talking about wrxs too, and Uk cars. All imprezas in fact.

I found this out from a regular contributor who has stripped many many of these engines and only found hydraulic lifters on legacy engines as standard.

Tone Loc

iTrader: (1)

Hasn't there been a couple of threads on 22b lately that people have bought heads thinking they were V3 STi but had got hydraulic lifters from an early impreza? My car during the winter you can hear the lifters 'pump up' on cold start for a few seconds, plus in the actual subaru service manuals for pre97s they have diagrams of the heasd showing the hydraulic lifters. Why would subaru issue these if they aren't infact fitted?

I'd be happy if my car doesn't have them, and i'd love to believe it. Just a bit sceptical.

And clues on who the person is Adam... wouldn't mind speaking to him about it.

Tony.

Pavlo

early heads (pre97) have mostly hydraulic followers, the RA heads have under bucket shim solid followers, and occasionally a WRX will have the same.

Paul

Andy.F

Std heads and cams from any model year 93-05 will easily make 400+bhp with only induction/exhaust and turbo changes. No need to go changing cams.
Mildly ported Sti 3/4/5/6 heads with std cams will produce 550+bhp on a fully prepared bottom end with a suitable turbo. If you need more than this then start looking at cams.
I'm still on std cams

Andy

Pavlo

I think there are good gains to be had with the right cams. Who has produced 550hp with standard STI cams, without using nitrous?

Paul

SWPGR

Andy,

Do you mean WRX std heads and cams can make 400bhp?

STi 5 heads with std cams? How many bhp can they produce without porting?

Can the STi5 heads fit on a WRX02 block without mods, and std gaskets?

Christos

Andy.F

Harvey runs std cams on his sti6, I'll initially have std cams in my car on the GT35R , want to place any bets

No reason to replace WRX02 heads/cams for 400bhp, they are capable of making that figure easily. Martin Metcalfe (ninnybobs on here) recently made over 400bhp on his 02 using a TD05-18G turbo/fmic/injectors/decat/headers/remap.

Andy

Pavlo

Andy,

How much more power would you get with better cams though, which you have already but are unable to fit for technical reasons? You note both yours and Harveu's cars as examples, and you both are well down on torque compared to others.

I think saying "you don't need new cams" isn't the whole story. Because it's not the case that you won't get improvements with new cams, especially with the 2.5 engines. JDM Sti cams are a good place to start, but heads may not always be easily available.

Don't knock it till you've tried it.

Paul

Absolute Shower

My UK 02 heads "tick" anyway (they've done 31,000 miles) so wonder if I need the shims done now...and if I'm doing that, might be worth just doing a mildly modified piper cams at the same time? I don't want to go mad, but think the timing might be right and get it all done...

Do heads normally need work after 31000 miles with oil changes approx every 5,000?

Pavlo

no they don't

Tone Loc

iTrader: (1)

Agree with Paul... i'd be a bit miffed if after only 30k they needed work.

Are you sure its the heads ticking and not noisy injectors etc?

Tony.

Andy.F

Oh yes it is. This guy is on std internals, YOU DON'T NEED NEW CAMS

Andy