TCT 8v => 16v head

KP · Post by KP » 08 Jun 2010, 09:34

Im wondering if its easy/possible to move my head from an 8v unit to a 16v unit.

With the cost of skimming and testing the head i could easily get a good used head locally from a 2.0 16v pug or citroen and fit it but im wondering if there are certain engine models it must come from or if it is just not possible?

Also im guessing it will decrease the CR as the head will have a slightly bigger void in it to accomodate the extra valves compared to the more flat face of the 8v head.

Is it worth doing at all as it would make the car more repsonsive in the higher rev range and breath a bit better but not sure how the ecu would take it either...

Anyone ever done this at all?

KP · Post by KP » 08 Jun 2010, 09:40

http://forum.205gtidrivers.com/lofivers ... 68335.html

Found this thread so really looking for a xantia 2litre 16v head and inlet manifold i think...

citroenxm · Post by **citroenxm** » 08 Jun 2010, 10:25

Wouldn't the 16v Piston heads have the Valve cut outs in the edges??

The 8v pistons dont, and they aint clearence engines..

Something to consider, you may need to swap pistons too..

I know of a xantia 1800 16v for spares up here, All I want really is the Air Con from it...

A 1997 r Reg car.. LX Spec

Paul

KP · Post by KP » 08 Jun 2010, 10:29

I think the head would have to be off a 2.0 paul so that the oil and water galleries line up.

Valid point on the pistons.

Asking a friend who used to have a 306 ralleye if any of his forum people have tried such a fete.

citroenxm · Post by **citroenxm** » 08 Jun 2010, 12:58

Heads are the same are they not????

paul

KP · Post by KP » 08 Jun 2010, 13:10

I thought the heads for the ralleye/gti6 were different from the xsi head which is the one used in the xantias or is it just the inlet plenum and cams that are different?

citroenxm · Post by **citroenxm** » 08 Jun 2010, 15:06

Ah I dont know KP...

Possibly.. but thats a field im not sure upon, Ive not had much to do with 16v heads..

Paul

KP · Post by KP » 15 Jun 2010, 08:51

Well after some digging im sure of at least a few things now to do this job.

A 16v set of pistons would be needed. How these would affect the CR is unknown though.

The best engine to go for is the GTi6/Ralleye one as the inlet plenum is much better and the throttle body larger in size so more air can flow more easily in to the engine.

The exhaust manifold would likely need to have some custom made jobby done on it.

If i ever get the money for this im going to get a cheap tct engine as there are a few about now, and whip the head off and get one of the 16v heads from the local spares place and then work on a custom inlet manifold with a welder so there is definately some kit for me to buy and i reckon for about £1k i could get all the btis together and sorted. then i'd just have to fit it to the car....

andmcit · Post by **andmcit** » 15 Jun 2010, 12:31

So where are these cheap TCT engines; I need one for my Activa and have
to try and beat off all the Barryboys who seem to have money to burn...

Andrew

KP · Post by KP » 16 Jun 2010, 08:20

There was an XM one on ebay for around £200 notes.

i offered the guy £40 but he declined but i still imagine it could be gotten cheaper.

Also Paul has just given away 2 short blocks. Stick the head and ancillaries on and away you go and as the engine has to come out anyway the extra work sorting the head from an old engine isn't a big issue...

Says he who is still trying to get time to get the head off his activa in situ

steelcityuk · Post by **steelcityuk** » 16 Jun 2010, 11:49

Hi KP,

Are the valves sodium filled on the turbo because of the exhaust temperature? I don't know, it's just a thought.

Steve.

KP · Post by KP » 16 Jun 2010, 12:27

Its possible.

Though with the head from the high end 2litre engines i would imagine they would be similar as their exhaust temps would get rather hot in hotter climes like southern europe when being pushed really hard..

Would have to cut one open to find out or ask the pug guys if any of them know.

Deanxm · Post by **Deanxm** » 16 Jun 2010, 17:38

Dont think they are filled, everything of the tct top end is the same as the XM 20i 8v one, you just need to change the camshaft.
Regarding the 16v conversion, i think bespoke pistons may be needed, the tct bathtub ones may hit the valves but the shorter flat top tct pistons could well work, that way you dont mess with the compression ratio too badly but then that depends on the combustion chamber volume on the 16v head v's the tct head but a slight difference would be fine i would of thought.

D

KP · Post by KP » 16 Jun 2010, 20:01

Dean,

Do you know how the cams differ at all??

Longer duration for the TCT ones maybe?

Deanxm · Post by **Deanxm** » 16 Jun 2010, 21:08

i can check for you at the weekend KP but eying them up it looks like the tct one has a shorter lift but a longer full lift duration, im kind of interested too so since the tct cam is on the bench i shall pull a NASP cam out and measure them up.

D