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Been a very long time since I looked at pre ecotec heads, last time in 2009 or 10?

have some ecotec ones as well.

was curious to see if ecotec ones fit pre eco block and it does line up with mating surface and gasket holes pretty good. Even the push rods line up well on 4 out of 6. the 2 that dont is due to flashing in the head which can be clearanced but still be be at weird angles.

Interesting seeing how different the combustion chambers are, frankly how shit the VN-VR ones are Those valves are very well shrouded

Also the saying ecotec ones crack due to lack of meat between valves. I think not after seeing how little the previous generation heads are and thats more so given than the ecotec heads I have are the "series 3" big valve heads.

the spark plug is better placed, further in the chamber in ecotec heads. Ports are 5mm longer in ecotec. They use kidney chambers compared to wedge as VN-VR use.

The chamber is heaps more unshrouded and shaped to induce swirl. The chamber is bigger as well but the ecotec use almost flat tops, only a fraction of mm dish.


VP head.
VY head with larger valves than normal ecotec.
ecotec 1.84" ? on top of VP valve

ecotec head on pre ecotec block.

pushrod alignment. Just an idea, but if it were to work longer push rods are needed, custom intake, some minor clearanceing needed to clear those angled ones. Custom cam as the ends of the pre ecotec heads have intake and exhaust lobs swapped compared to ecotec. Look at the valve placement in both heads.

the issue with the ecotec heads is not the distance between the valves, its how much meat is behind it before it hits the water gallery..... after finding a few that were cracked at my mates workshop on a Friday arvo we decided to get the die grinder out and follow the crack, it didn't take too long to get to water!

having said that I have never compared an earlier head in that area as we've never seen one cracked!

from my understanding there was defective castings in early ecotec heads. later ones are pretty meaty and dont crack. But also overheating seems to be the trigger for the early castings to crack

From pics of sliced up ones on the net they appear to be about 4-5mm thick there. How thick was your one?

haha id say the factory calibration starting the low speed fan at 105 degc off a 89deg thermostat didnt help either. highway 89 deg due to airflow, traffic straight to 100 deg, start moving again, back to 90. heads dont really like constant temp swings like that.

Why would you want to put late heads on an early bottom end?

yeah that's the million dollar question, did the head crack from over heating or did the overheating occur from the crack

I've seen most of the cracks in VS and one VT ... I know the VT and at least one of the VS was removed from the car due to over heating and suspected head gaskets....

as for the depth of the head material, it was 2-3mm in the thinnest part.

I've removed a few heads from pre ecotec engines that have had cracks between the valves, usually the front cylinder on the left & rear cylinder on the right.

Biggvl wrote:Why would you want to put late heads on an early bottom end?

its been a big goal for many apparently as the older block has much much better rod ratio and can be easily stroked without compromise of the already not so great rod ratio of the later ecotec blocks.

More torque can be made with longer rods vs stroke, less wear on the engine as well due to less side thrust of the pistons. The disadvantage is heavier rods but custom ones can fix that


So if it was to be possible, the best of both worlds v6 would be created.

Holden202T wrote:yeah that's the million dollar question, did the head crack from over heating or did the overheating occur from the crack

I've seen most of the cracks in VS and one VT ... I know the VT and at least one of the VS was removed from the car due to over heating and suspected head gaskets....

as for the depth of the head material, it was 2-3mm in the thinnest part.

should get some different heads and band saw them all to compare.

there was something like 3 different casting numbers for ecotec heads.

I've a got a pair of old VS ecotec heads, I might take one to work and let the power saw have a go at it.