Head photo request

[novaguy08]

Hello gents, im trying to squeeze a bit more poke out of my 1.2 whilst im saving for a 1600 lump and i was wondering what the exhaust ports look like on a 12NZ and not wanting to start removing the exhast manifold as that will probiably entail me things removed from the head that have broken, so im not interested till i take the head off for now..............

What im REALLY interested in here is a photo of the exhaust ports on a C12NZ and if possible C14NZ as i might be able to get a hold of a 14NZ head if its better

ta peoples :D

[napalm_27]

look on ebay at corsa c12nz reconditioned head there one on there with a pic of the ports mate

[novaguy08]

so they're round exhaust ports then.......... hmmmmmmmmmm i thought that the 12NZ head was very restrictive, as i know of a 14NZ at a local breakers i was interested in pinching the head, inlet, exhaust from cant find any pictures of the 14NZ head, are they the same with just a different bore?

[Riggy]

the 1200 head is a very good head actually,

best bet for some poke would be to fit a 1300 inlet and carb , the either 1300/1400 manifold and exhaust , if you want to go further the use a 1300 crank and rods with you 1200 piston , which will increase the capacity to 1400 ish

[novaguy08]

in inj riggy C12NZ not 12ST mate

[napalm_27]

you can still fit a carb to it
and its only spi so not much hardship to change it over

[novaguy08]

dont want to fit carb to it, means i need to spend out more monies, and then its a wiring issue as i would need to fart about with the engine looom

[jimbob-mcgrew]

spi has the turd square inlet ports.
to convert it youll need the cyclinder head with the inlet and carb, maybe the mechanical fuel pump and the dizzy to go with it, prob cost you a new water pump aswel as a cambelt too.
save your money id say mate, its alot of hassle for 9 brake, put it towards the 1600 :thumb:

[novaguy08]

i intend to jimbob, its the exhaust sides of things im worrying about right now

[jimbob-mcgrew]

understandable you dont want the hassle and cost of carbing it.
keep it in mind that the biggest bottle neck of that engine is the fact that its spi. in which case id reccomend not to spend ANYTHING on it. maybe advance the timing slightly and put the higher grade unleaded in it lol

[jimbob-mcgrew]

from what i understand, all 8 valve exhaust ports are the same, so in theory you should be able to use your 1.2 exhaust on the 1600 till u get something better sorted.

[novaguy08]

i already done that, the exhaust work is to pre-empt the 1600 conversion (i hoping it fits ok!) and to relieve a bit of boredom due to lack of power! just wondering whats the bore on a 1400 spi? and does anyone have a photo of the inlet and outlet of the head?

[novaguy08]

the conversion is coming later..... much later im going to be doing it in a year or two once i saved up for insurance & the mechanicals i need

[jimbob-mcgrew]

i wouldnt bother with something half way mate, youll only waste money in the long rung and have to change the manifold twice, might aswell go straight for a 1600, then its ready to rock for the new engine, plus youll get the maximum gain of power you can for the mean time, which will be a laughable 1 or 2 horse lol

[jimbob-mcgrew]

oh that much later... fcukit, whatever mods you do is gonna void your insurance anyway

[novaguy08]

not changing the exhaust manifold (unless i can get my greasy lil mits on a 4 branch very cheaply!) im only interested in the 14nz head if the inlets are different and look like they offer better flow compared to the 1.2 ones, however judging by the looks of the power rating erm............ no springs to mind! so ill stick to the 1.2 head and just finish off tinkering with the exhaust! who says i aint going to tell the insurance company........ but as i said im not going to bother with it unless the 14NZ inlet is a better flowing system compared to the 12NZ which i dont think it is!

[jimbob-mcgrew]

youll probably loose power fitting the 1.4 spi head as it'll prob lower the compression within the bores and make a lousy explosion. if your changing heads u might aswell go for a 1.2 carb, its the biggest restriction on that engine, will get u 9 horse, then slap a 1600 exhaust system on it in anticipation for the engine conversion, will probably give u another 4 horse

[AlexW]

14nz is excatly the same, square inlet ports/round exhaust ports like all 8v's.

Even the NV has the same head.

[Riggy]

in inj riggy C12NZ not 12ST mate


sorry dude totally misread what you put lol , adam has a guide on how to tune a 1200 spi in the articles section , wont go far wrong with that

[novaguy08]

yeah i read that one riggy, i already put the bigger CAM in there which im happy with, im doing some exhaust work soon but im not going to take it much further then that as ill just be throwing money that i can be spending on my engine conversion away
I wont bother farting about with the head then, ill stick with the one on there and just fart about with the exhaust and might have a tinker with the head when i can be bothered to do it & like i said that will be it unless i can get my greasy lil mits on a 4 branch

[AlexW]

If youve got to do the head gasket get it skimmed and see if they will take off a bit extra to up the comp..

[novaguy08]

well im intregued to find out if the injection tb will fit on to the carb inlet manifold if so ill grab myself an ST head and get it skimmed
I would have thought that skimming a bit off the head would change the bore on the head?

[AlexW]

Injection inlet is totaly different to the carb one. You would eather try and make the spi inlet rounder, or just run it with mismatch ports.

And skimming it wont, same as doing it like you should when the head gasket goes. Usualy heads are good for a few times (Clio i know of has been done 3times)

[mikey14sr]

If you'd posted this yesterday morning, I'd have sold you an SRi manifold (still had a lambda sensor in it) and twin downpipe that would have helped a bit, unfortunately it got weighed in along with my old SRi bottom end.

[novaguy08]

mikey, i did post this yesterday morning lol never mind for now, think im just going to get either an early exhaust or cutting & shutting my current one to make it straight thru
AW06 what i mean is getting a carb head from a 13s (as its the closest bore to the C12NZ) and using that with a carb inlet and bolting the inj tb on it, as the carb head has better flow i might get some more poke from it, however one would think that the torque might drop off a tad.
I read somewhere that the 1.4 injector is quite good for more power, obviously it would over fuel but would it over fuel to the point it would loose power or would it work ok?

[AlexW]

The TB wouldnt fit the inlet, You could fit the 1.2i inlet/tb onto the head, but it would be mismatch ports.

1.4 injector is only worth it if you have done some seriours work to the engine, not like your doing.

[novaguy08]

ok then i wont bother getting the 13s head an the injector!
Just the exhaust for now!