Ecotec Cylinder Head Cross Section

[Grimes]

A short public service post. I found it difficult to find good cross section images of the ecotec heads on the net. I did some port matching on mine and resorted to hacking up the old cracked heads to establish the wall thicknesses. Inlet and exhaust are shown plus a shot showing the presence of a cooling jacket between the two ports at the narrowest points. Mine were cracked at the thinnest section between the two seats (marked by a small pink ink mark). It hadn’t reached the cooling jacket (or maybe had but symptoms were still self erasing), but there is surprisingly little in terms of metal between the inlet and exhaust at their closest point. You can also see that they’re already a pretty open port design. Opening them up deterred me from further porting; I wouldn’t be operating at high enough rpm to see any material benefit, just putting the engine at risk. Enjoy.

 

[RWD4ever]

Interesting. Wondered why it was so hard to bleed the air out when filling with coolant.

 

[Grimes]

A few more with some scale and detail. As for bleeding, I think we’re just lucky they not alloy. I heard the VL heads were a nightmare with air locks. I can appreciate why.

 

[Immortality]

Yes the ecotec heads are known for cracking between the valves. I believe the casting was revised at some stage to reduce this issue but not sure when the change occurred or if we actually got them here.

I did once see a flow chart for a stock ecotec port and they continue to increase flow past .550" valve lift so it's not a bad port. Looking at the cross-section it seems it may benefit from just a little throat work, especially around the short turn but really not much that needs touching.

 

[Grimes]

Yes the ecotec heads are known for cracking between the valves. I believe the casting was revised at some stage to reduce this issue but not sure when the change occurred or if we actually got them here.

I did once see a flow chart for a stock ecotec port and they continue to increase flow past .550" valve lift so it's not a bad port. Looking at the cross-section it seems it may benefit from just a little throat work, especially around the short turn but really not much that needs touching.

Mine were ‘96 vintage so probably the weaker ones. That said, before I went for a new set from Revhigh, I stripped a few heads at wreckers from VT Commodores and they were all cracked in the same place, not that any of those engines appeared to have suffered any issues looking at their internals,ie clean plugs and chambers, clean coolant galleries, etc.

I should plug Revhigh and Mace Engineering too. Couldn’t recommend them high enough for good comms (lockdown and all), pricing and sorting the odd issue out. Spent a few $k at each.