GM vs Coscast heads

[draper]

whats the difference between these heads ? why is the coscast one better ? i think i read somewhere (a long while ago) that the coscast ones are better because they dont go pourous as easy but you can mod a GM one so it doesnt do it either ?


i also vaguely remeber a lad i used to hang round with who worked at vauxhall telling me that when the first mk2 astra GTE'scame out they were deemed to quick and were de-tuned - i presumed these earlier engines where coscast heads ? :confused:

[Timmy]

yes coscast are better for not going pourous, SBD use coscast for that reason, i dont think Gm one's can be modded as the metal between the oil and water line in the head it thinner in the GM ones in side the head.

[Iain]

From this site (http://www.sbdev.co.uk/History_files/History_BudgetHorsepower.htm) (could be useful for some info?):

Therefore any C20XE built up to about 1990 will use a Coscast cylinder head, whereas beyond this point GM switched to a production item, cast and machined by Karl Schmidt in Germany.

[Tim]

the coscast head were actually developed by cosworth and were used on the early xe engines, imagine the smile on my face when i stripped my ?150 xe lump to find a shexy coscast head on it, i was a happy boy.

apparently they have slightly more power as well, but im no hexpert, so whats the deal?

tim

[draper]

just dug out an old total vauxhall and found some info

the only place the coscast head is better is in the oil galleries, 2 of which run through either side of the head and in GM-cast heads tend to be more pourus in this area. the galleries can be repaired or can even be re-sleeved ?

[draper]

From this site (http://www.sbdev.co.uk/History_files/History_BudgetHorsepower.htm) (could be useful for some info?):



good link, ill read it properly later as im waiting to be picked up for some beer garden shennaigans !!

[Stuart]

the gm head dosent "officially" go porus... it merely cracks betweek oilways and water ways if you do the bolts up too tight etc. You can easily fix the galleries with drilling and tubing etc so its no real biggie imho.

yes its nice to try and blag that you have a piece of cosworth development on your car but hey... you dont hear the 1.4/1.6 16V boys cumming in their pants because lotus designed their heads do you lol

[General Baxter]

you dont hear the 1.4/1.6 16V boys cumming in their pants because lotus designed their heads do you lol


pardon

SPERM lol

[loggyboy]

But one of the main reasons why the XE is such a good engine is the head design by cosworth. So why not be pleased about it? I dont think any1 was bragging tbh. Im sure if it was more common knowledge that the BVs were lotus designed it would be mentioned as much.

[draper]

thanks for the info people, getting the idea its not worth spending the extra cash just so i can say "ive got cosworth gear on my engine"

if i wanted to do that, id but a fooking cossie !!

[Adam]

But one of the main reasons why the XE is such a good engine is the head design by cosworth.
Why tho, afaik, GM heads are just as good as the Coscast ones, apart from going porous.
But no power differences.

[draper]

thats what im now thinking, and if you can get a GM repaired then no point shelling out !!

going to be ringing "cylinder head developments" soon and getting some prices for there work. been reading about them in total vauxhall and im impressed by some of there figures !!

[Ste L]

only reason for power difference, was just the most xe with gm head, usually have the cats, and they sap power

as for the pourous head.. my mate can fix that...
here's his site about it ;)

http://www.orsas.com/CarStuff/cav/

[Adam]

Yep, people see the early XE's have 156bhp, but probably forget that they dont have CATs.

[Tim]

yes its nice to try and blag that you have a piece of cosworth development on your car but hey...[/quote]

dont belive i was bragging, just commented on how pleased i was to have sourced a xe lump with the coscast head for so little money (?150).

if you had the choice which would u prefer to buy?:thumb:

[Ste L]

the one with less miles on it personally

couldn't care less gm or cos cast head

[Stuart]

^^^ bingo. id buy the one in "best" condition then if it was a gm head id get it repaired beofre fitting as prevention is better than cure ;)


also iirc cosworth didnt design the ehad as such, they had a small hand in it but it was the casting process they messed about with hence coscast....

[draper]

only reason for power difference, was just the most xe with gm head, usually have the cats, and they sap power

as for the pourous head.. my mate can fix that...
here's his site about it ;)

http://www.orsas.com/CarStuff/cav/

brilliant site that ste, cheers

gonna strip mine down at the weekend if i get time and have a good nosey round, will probably get mine reapired before it does/might go pourus