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[Martin_1962]

What compression ratio would you get?

[ballcock50]

If you can lay both 3l & 2.5l heads side by side you may see any noticable differences and check the combustion chamber volume as well.

[Marks DTM Calib]

I did some calcs ages ago, its about 11:1 or maybe slightly higher.

2.5 heads would need porting though as the inlet ports do appear to be slightly smaller.

Remember, when buying heads, you MUST have the matching cam caps

[Martin_1962]

I did some calcs ages ago, its about 11:1 or maybe slightly higher.

2.5 heads would need porting though as the inlet ports do appear to be slightly smaller.

Remember, when buying heads, you MUST have the matching cam caps

Not that high then - could be interesting with super unleaded or LPG

[Kevin Wood]

I did some calcs ages ago, its about 11:1 or maybe slightly higher.

2.5 heads would need porting though as the inlet ports do appear to be slightly smaller.

Remember, when buying heads, you MUST have the matching cam caps

.. or you'll end up like this mate of mine.. rebuilding your engine in a Hotel room and trying to find bits for a Cosworth YB in Arizona. I bet they loved him.



Kevin

[aaronjb]

I did some calcs ages ago, its about 11:1 or maybe slightly higher.

2.5 heads would need porting though as the inlet ports do appear to be slightly smaller.

Remember, when buying heads, you MUST have the matching cam caps

.. or you'll end up like this mate of mine.. rebuilding your engine in a Hotel room and trying to find bits for a Cosworth YB in Arizona. I bet they loved him.



Kevin

  Ok.. there has to be a good story behind that one!

[Kevin Wood]

Ok.. there has to be a good story behind that one!

Yes. It started off with some brief fun and games running a lot of boost and then the realisation that the petrol out in the sticks in the US has approximately the octane rating of gnat's pee.

Then followed an episode of getting some rednecks to try and weld, and then skim, the head to replace the material eroded away by the detonation. Sadly, they didn't appreciate that, unlike on a side-valve V8, there isn't inches of material spare on a Cosworth head.

Then a good head was duly dispatched from a saviour in the UK.. sans bearing caps.

Finally, after much blood, sweat and tears fettling the car back into one piece again, and trying to select bearing caps that gave a vaguely sensible clearance, it came to pass that one of the camshafts became 3 shorter camshafts.

Kevin

[aaronjb]

Finally, after much blood, sweat and tears fettling the car back into one piece again, and trying to select bearing caps that gave a vaguely sensible clearance, it came to pass that one of the camshafts became 3 shorter camshafts.

Ouch! I bet that made a lovely noise as the various bits of cam divorced themselves from their neighbours!

Reminds me of why I didn't take the cams out during the strip down of the Nissan - one of the bolts into a bearing cap appeared to be cross threaded (certainly it was way, way over torque spec to turn but still turning without actually clamping down) .. so I left it and ran away as fast as humanly possibly - but it probably explains why the top end was never 'quiet'!

[Martin_1962]

Helicoil?

[Kevin Wood]

Ouch! I bet that made a lovely noise as the various bits of cam divorced themselves from their neighbours!

It happened as he was tightening down the bearing caps.

Kevin

[MutantCav]

the Mutant Cavalier had a 3.0 bottom end 2.5 top end Omega engine...built by Courtney though and apparently cost a fortune...