Welded cylinder head mod?

Post Fri Sep 14, 2012 11:52 pm

I've read in some engine build threads that m20 engines that have big turbo's sometimes have water galleries in the cylinder head welded. How is this done and why? I haven't seen any pictures of this mod or an explanation for why it's needed. Anybody?

Post Sat Sep 15, 2012 9:39 am

With the higher amounts of pressure and more fuel/combustion, it stresses along the water jackets, and can sometimes crack the head and/or blow a head gasket along the narrow parts where the cylinder bore is closest to the inner wall of the jackets.

Where you see the welds, normally there is a long channel that connects the two openings on either side of the welds (water jackets). And how close they are to the chamber. After getting them welded up, and obviously skimmed flat again, it helps to reduce chances of damage at high boost.

(Thanks Ross for the pic

)

Post Sat Sep 15, 2012 1:17 pm

Ah, I see. Does it affect the cooling at all? Is it a worthwhile mod for a non turbo engine?

Post Sat Sep 15, 2012 1:50 pm

It *may* have a small effect on overall cooling, but if your water pump and radiator are healthy, shouldn't make that much difference, assumingyou don't live somewhere super hot like the middle east - in fact, you may get away with just doing the exhaust side (hottest part of the head is always the exhaust valve seat - inlet side is up to 30 degrees cooler...)

For an N/A engine? I wouldn't bother - cylinder pressures aren't going to get high enough to distort the head that much...

Post Sat Sep 15, 2012 5:24 pm

Mikey_Boy wrote:It *may* have a small effect on overall cooling, but if your water pump and radiator are healthy, shouldn't make that much difference, assumingyou don't live somewhere super hot like the middle east - in fact, you may get away with just doing the exhaust side (hottest part of the head is always the exhaust valve seat - inlet side is up to 30 degrees cooler...)

For an N/A engine? I wouldn't bother - cylinder pressures aren't going to get high enough to distort the head that much...

I've just had the gasket push out on the intake side.

Post Sat Sep 15, 2012 6:58 pm

Without any major mods, that just may be a sign of old age or incorrect torquing of head studs/hard driving.

Post Sat Sep 15, 2012 7:21 pm

E30_Crazy wrote:With the higher amounts of pressure and more fuel/combustion, it stresses along the water jackets, and can sometimes crack the head and/or blow a head gasket along the narrow parts where the cylinder bore is closest to the inner wall of the jackets.

Where you see the welds, normally there is a long channel that connects the two openings on either side of the welds (water jackets). And how close they are to the chamber. After getting them welded up, and obviously skimmed flat again, it helps to reduce chances of damage at high boost.

(Thanks Ross for the pic )

oi sneeky git lol
i never see this like they say i done it on precaution but it really doesnt need doing as for N/A engines there is no pros for getting it done
as for cooling mine is fine doesnt even hit half way on my gauge and still quite cool so i personally dont think it has any effect on cooling