ok I managed to acquire an head from a local scrap-yard for a very good deal.... My aim being to do a little "psychiatric re-arrangement" on my Ute, but without it having to be out of service.

The engine in question...



A15, stock block ,chopped rods and running a shim-plate with Langley pistons on 20Thu.

GT1749 Turbo, Custom inlet and a set of 4AGE injectors. Gotech MFI for the brains...

this setup runs perfect, has been for almost 1.5 years now.... so I guess I shouldn't screw with it, since it ain't broken... hmmmm how boring... :)

it's able to run 1.1 bar's boost on some rather crappy "horse urine" for fuel we have here (93RON).

my aim is not to increase flow with this exercise, but rather to increase the engines stability under boost, IE. to get the chambers such that I can actually add more timing to the boost I am running at now....






obviously that could also be construed into me wanting to run more boost... but I promise... that is not it

now my question... is this head a good head, it has 29mm exhaust-valves and 35mm inlet's and it runs double valve springs.... I'm not sure whether that is std on all heads. No markings or numbers of any kind that I can see....

Good score dude!
What you have there is an A12 GX head. No "H" number, small chambers, A12 sized valves, and the four larger sized water galleries below the intake ports. Thats pretty much the best head you can get. (There is a better head, but you wont find one anywhere)
A cylinder head workshop can remachine the seats to accept the larger A14/15 valves.
These have a bigger (Taller) intake port that the standard Oval port heads too.
The only down side is that these heads also have smaller chambers, so this will likley raise your compression, and perhaps even limit your ability to run more spark.
If I were you I'd find a reputable head shop, and get them to go to town on it. Force fed motors absolutely love big porting.Definately go for bigger valves. (at least A14/15 sized ones)

Sorry im off topic here but out of intrest wat are u running timing wise?? YEa great score on the head pitty u dont want high comp.

oh this is awesome.... now for the better part of this tail.... the guy at the scrapyard, where I got this head, has like 10 of them on a shalf, just gathering dust..... he charged me R750 for it, and I'm sure he be coming down if I where to tell him I'll take em all..... any takers? maybe... maybe...




this is my fuel and timing maps....

timing on the right.. at full boost on rev-limit aprox 21

Ok Just checked the currency difference an thats about $125 Ozzie Whats the postage /freight costs going to be??

I have no Idea....

I just got back from the parts store....
got me a set of A15 valves, R170.73 for the set of inlets(37mm)
and R213.41 for the exhausts(30mm)...

what a pleasure....

will be getting the machining done tomorrow.... hopefully that will also not be to much

well, after a little bit of lathe maneuvers, I managed to get the bigger valves to be lighter than the std small valves... inlets weigh in at 60grams each, 4 g down from the std ones. the exhausts I managed to take a whopping 6 grams out of... from 58g to 52g each... they are all respectively now the same weight as well...

Mate, I don't know if the exhaust valve seats will be able to be opened up to take your 35mm valves. The standard A14/15 exhaust valve is only 30mm. Big valves are all good, but you may have to have a larger seat fitted to the head to make the 35mm A12 inlet valves fit in the exhaust holes. No problem, but it might cost more than a straight seat recut.

indeed yes... my typo.... that is not 35mm x-valves. much rather 30mm.... you have a sharp eye.

I was fretting that I had put you wrong. I even went back and checked the valve sizes in wiki.
When I had my GX head overhauled, I grabbed the wrong exhaust valves, So I'm only running 29mm ex valves. I wonder how much power thats costing me?