As above please. all the positive points. I really dont think there is any negatives but if so, please list them too.

Many thanks.

If your missus gives you lots of headwork, it means you will be very happy indeed.

ok ill kick this off then with a few generic points

positives

- better airflow meaning more fuel / hp
- increase in peak bhp

negatives

- can result in loss of low end torque if ports and throats opened up
- larger valves may result in seat cracks, depending on how close they are
- surface grinding / skimming can reduce the deck thickness that can result in 'easier' warping as less rigid


given that heads, and in particular valve seats are in my experience one of the biggest contributors to quick power loss due to harsh fuels and seat pitting a good head job is essential to making sure all the power remains.

a leak down test is a reliable way of determining if the head is past its best

in terms of defining... different options are available depending on what is required:

- valve reconditioning / replacement if stems and tips are worn
- valve seat cutting to restore seat integrity
- valve back cut to increase flow
- multiple angle valve seat
- valve throat work
- head porting
- valve guide replacement
- combustion chamber reshaping
- in / ex port gasket - manifold matching
- head face skim
- oilway clean
- head casting chemical clean

Essentially time is money and many heads don't receive the gold treatment as people don't want to spend 000's on a head.

One of the most common faults i find is that guides are fitted and the valve seats are not concentric. this is because the guides do not have the holes cut properly. therefore after fitting new guides the seats should be cut and lapped.

Also, due to the guides being pressed into the head, they should be measured and reamed as necessary.

Rudi stop googling these things.

Define Headwork = BARBZ

Oi you behave!

Oh another thing i see fairly often is the fitting of bronze guides in road heads. Best for race doesnt mean best for road. Some options result in high wear rates which is fine if you intend to strip and rebuild the engine every 500-1000 miles but not on a road car!

Oh and another... Many head valve seats cut with manual carbide cutters often have chatter marks. Old school valve lapping seens to be a dying art.

amen to this, bro

chav.

Define head work = highly variable standards of prep and cleanliness.

There is two sides to it, a lot of the stuff already listed is general rebuild and reconditioning procedures that would be standard practice.

The main goal I guess is to get as much air into and out of the cylinder with little fuss and as efficiantly as possible, doing so at all valve lifts and without sacfificing air velocity at low rpm's

Indeed, although throat, chamber and porting isnt rebuild territory by any stretch.

It is all about the shape imo, this is one area where size matters less, in fact too large can be bad depending on what youre after

Gas speed is key, but there is invariably a trade off between a torquey spec, with say narrower paths and a higher rev / race spec modification

Like anything in an engine it needs to looked at as an area that must complement the next whilst taking into account the associated parts around about. A power target,rpm range and driving style start the ball rolling in the combustion area and so then starts the chase that goes out of both the inlet and exhaust ports all the way out to atmo. Mess up the head work or fail to complement it and so then the package suffers.

"It is all about the shape imo, this is one area where size matters less, in fact too large can be bad depending on what youre after"

I agree, shape is very/super important but it must be used within relevant sizings as determined by target and within the contraints of the particular port.
Gas speed, now there's a big subject!! Average or localised, inlet or exhaust, just the very beginning of the minefield of considerations.

You dont need to know the definition,all you need to know is the following.
And this is speaking from experience.
One word.



BARBZ.

barbz is the best head i ever had

Well done by the way on your motor,great results.

Thanks mate, it feels bloody good.

Headwork = Expensive..

I mean really expensive..if you want it done correctly using an experienced tuner.

Results = huge smiles

And empty pockets.

Indeed. Most people simply dont appreciate not just the skill required but also the number of hours required to work a head.....

As expected, more time = more money.

Following the above formula, cheap = crap.

I am modifying a head for my mini engine build.

It is not until you compare the work carried out on 'decent' heads and cheaper heads that you can appreciate the differences. I expect that many wouldnt even see the differences and the intricacies are shielded by valves, etc.

Want the best, expect to have to pay for it

This is from my personal expirience .... Head been done at Guy CRoft and cost 3k , and let's take NIgels coop to compare which has BArbz head cars had pretty much indentical set up , and power out put but the
Prices are day and night .....
When my car was rolling road and mapped it wasn't not running 100 % , but it was safe , next mapping it showed problem with wastegate , so when it will run 100% then we can compare the difference with other cars
FOr now I would spend 2k on other goodies like tubular man etc....

"This is from my personal expirience .... Head been done at Guy CRoft and cost 3k.."

Head prep: you quote my prices without asking me?

If you're talking about a 20v originally done for Wallace Performance it cost them £1638.80 + vat not your £3k to do the list below incl 12hrs dev flowtest which I undertook because I had not done one before, approved by the client BTW. Don't feel uncomfortable about disclosing this it got sold without ever being run and I have no intention of doing another, the 20v is a lousy design I'd not care to work on again.

GUIDES OUT
NEW GUIDES GC RACE TROJAN
GUIDES FIT & HONE
VALVES 20 X REGRIND, STEM POLISH, TIP GRIND, FACE & INLET BACK GRIND
IN/EX SEATS RACE SPEC GRIND, VALVES LAP AND SEAL TEST
FLOWBENCH DEV ONE INLET AND EX SET BARE PORT FLOW
FLOWBENCH DEV ONE INLET AND EX SET FINAL VALVE IN FLOW A
PORTING COPY DEV FLOW TO OTHER 4 PORT SETS
CC PREP
REFACE
SPRINGS 20 PAIRS OE COUPE
VALVE TIP HT ADJUST TO OE SPEC TO SUIT HYD LIFTERS

If you want to include vat which was 15% then that's up to you it's not a tax imposed by me personally..

G

I reckon there's more people that wouldn't care to pay that sort of price again.

That's what i've been told by Matty , it cost him 3k and his kindly sold it to me for 2k !

"I reckon there's more people that wouldn't care to pay that sort of price again"

no question about that!

But it really is a lousy design - nowhere near as good as the Integrale head. I'm a big fan of F/L but they got the design badly wrong on the port layout on the 20v. Not impressive from such a clever and innovative organisation.

Just saying that's all.

G

Guy - I thought you said (on the 20VT head thread on your forum) that the base design of the head was very good - I seem to recall you being quite complimentary about it

FWIW, my opinion is that if you're trying to build a powerful engine, the VAST majority of the gains will come from a re-worked cylinder head.

When Barbz did my head for my 400bhp build, I was wondering whether it was money well spent (bear in mind I'd been running 300+ bhp on a GT28R and a Unichip beforehand)

However, when my fuel consumption dropped from 240 miles per tank to around 300 miles per tank, it was pretty obvious that the headwork had increased efficiency, meaning that I was using less fuel for any given situation (or if you prefer, I could generate more power out of the fuel I was using)

Quite simply, my cylinder head has paid for itself around four times over with the reduced fuel consumption

No-brainer....

However, from what I've read on this and other forums, it's spectacularly easy to get a head wrong. It is NOT simply a case of opening the ports up and making all the edges sharp and the surfaces shiny.

Also (I'll let Guy comment on this one) - I reckon a brilliant head with ancilliaries that can't take advantage of it is always going to dissapoint. There's no point in having a head that can flow loads of gas, if the turbo / injectors / intake / air filter etc etc can't deliver the gas (or if the hot side of the engine is restrictive, like mine was while I was still running the SuperSprint)

Original thread about GCRE work on Matty's head (Wallace Performance)

Original thread about GCRE work on Matty's head (Wallace Performance) (link)

Are you sure about that?!

g