Aztec Performance Ltd

iTrader: (234)

Which would be better suited for a built 2ltr looking to for maximum midrange punch (most likely on a TD05 variant turbo on high boost):

STi5/6 Heads or:

UK Heads +
Supertech Nitrided Valves (oversize 0.5mm?)
Supertech Dual Valve Springs
Supertech Titanium Retainers
Supertech Spring Seats
DH22 Profile Cams


Value for money spending on heads?

500

would have thought that uprated heads would be better. I know that the earlier casings were the same weather it be UK, WRX or STI, so wouldn't have thought that the later cars would be different.

I would say to get a set of vernier cam pulleys to optimise cam timing for the midrange punch that you are after

Adam.

Slowboy Racing

The second list is nice but far more expensive the DH22 Profile is good for mid and low down power, not sure what they would be like if your planning on 8000RMP limit or how they compare to the version 5 sti cams after all what you gain down low you generally loose out on top end i would expect the Version 5 profiles to carry more evenly across the rev range but have less pull low down. I would also add head work to your list to get the best gains using those cams, this will also increase the cost further and imo would a must if you go this route.

There are also more profiles available now I think the dh22 was used a few years back and are very popular, speak to Kent or piper they can offer more advice on profiles that suit

With that said it’s really down to your budget and what you plan on using the car for, after all on a well built 2lt it will happily rev to 8200 and some i would be looking at cam profiles that work higher up the rev range to make best use of it. One thing is for sure if you’re planning over 500 its best to go with solid valves or at least loose the sodium filled exhaust valves.

Cams are the life and soul of the engine choose them well.

Aztec Performance Ltd

iTrader: (234)

budget is tightish.

more importantly not chasing big numbers. Sub 400/400

its a case of....might as well do it rather than need to.

I like to have a setup which the mapper finds is v good to map.

Which single componets work well on there own?

£200ish for a set of valves
£200ish for a set of sprins/retainers/seats
£250ish for cam reprofile

(off the top of my head)

500

you are looking at way more than 200 for a set of valves for a start

I'd stick with the STI valvetrain and add a set of vernier pulleys so that you can get the best timing for the power band that you want if you are sticking to 400 ish.

Aztec Performance Ltd

iTrader: (234)

nope. not if you shop around.

I dont have STi heads to start with, which is what makes the uprated bits seem like good vfm, if changing from UK heads anyway.

SSCJAY

You can get a full set of Supertech valves from the states for £150 plus Shipping & any Dutes!!

Or Crower ones even cheaper!!

If 400 / 400 is the goal then standard valves would be fine, but seeing how cheap supertech ones are would be rude not to. Just get a good set of cams with uprated/double spring set.

Slowboy Racing

There is no point even considering that list if that is your plans, the sti 5 heads will be fine.

Aztec Performance Ltd

iTrader: (234)

^...

p1prodrive

iTrader: (3)

why dont you buy sti 5/6 heads ready to fit ?

jaytc2003

iTrader: (1)

he already has the uk heads, he is wondering for the cost of the sti v5 heads he could uprate the components on the uk heads and is just after opinions on what would be better

Slowboy Racing

Apologies I skipped through earlier.

Ok you have uk head casings so i worked out the aprox cost of the above list minus any head work or building excluding valve guides or stem seals to be around £900-£1000 If you have the heads worked and built I would add on another £500 so you are now looking at around £1500. To me this doesn’t justify speeding that amount if you are planning on a 400/400 build your uk heads alone will flow enough to see this figure.

The other alternative would be to sell your existing heads for anywhere between £100-£200 and put that towards the version 5 sti heads which will perform great on a well set up car leaving you money spare.

I can’t really comment between the comparisons on the two different head set ups running at that level as most imprezas that I no of running work heads are generally in excess of 500.


Hope this helps.

ZEN Performance

That's an expensive way of doing it.

Aztec Performance Ltd

iTrader: (234)

Yes, as Jay says I'm looking for what would work out better on uprating bits on mine or buying STi5/6 heads.

In terms of cost....both options are very similar to one another from initial calculations.



Paul: Expensive way of doing it?



Cheers,

Bob

p1prodrive

iTrader: (3)

just like i said on my earlier post.... buy sti heads, that would be the most cost effective way of doing it.

Aztec Performance Ltd

iTrader: (234)

costs look quite similar tbh and in any case I would change the valves on STi5 heads anyway.