mjensen

I have numerous 944 heads and trying to tell the difference from a 951 head. I assume in my collection I have a 951 head, but am uncertain...thanks...

Darwantae951

On 951 heads, the exhaust ports have ceramic liners and the valves are sodium filled (unsure if you can tell the difference externally because I've never seen a 951/944 valve side by side.

Thom

If you can get rid of carbon deposits on the exhaust ports of the 951 head you should see the ceramic liners that are white.

Olli Snellman

951 head have a stamped "T" letter on the intake side of the head.

Thom

My 2.7 head also has the "T" stamped

IIRC what's stated the WM, a T should be stamped to inform that the head was skimmed/resurfaced?

Olli Snellman

Three factory new 2,7L heads i have does not have stamped "T".

Thom

If they are new they have not been skimmed/resurfaced, so that makes sense.

Chris White

944 exhaust valves have a depression on the face of the valve, 951 valves do not.

OntarioTurbo

I believe there is also a difference in the check valve spring rate for the oil side of things as well.

Darwantae951

There's an oil check valve in the head?

Jfrahm

Yes, if your head is rebuilt it's good to make sure the check valve is working and not full of swarf or glass beads. And that it is actually installed, for that matter.

mjensen

I will take a look tomorrow at the T and the valves. I appreciate you help...

OntarioTurbo

Yes, the check valve in the turbo heads vs the na heads has a tighter opening so that oil pressure is built up in the crankshaft drive and turbocharger before filling the camshaft housing.

The other differences according to Information Technik are as follows:

1. Cast-in thermal insulating ceramic exhaust ports
2. Exhaust valve guides which are longer and made of a different material
3. Valve seat inserts are made of a material with better heat-proofing properties
4. Valve seat width for exhaust has been changed from 2.0 mm to 2.5 mm.
5. Intake valves have a circular journal
6. Exhaust valve head is completely flat
7. Exhaust valves parttially filled with sodium
8. Valve spring has an installed force that is 20% higher
9. Valve spring length is 58 mm for turbo and 52 mm for na
9. The exhaust valve springs are pre-loaded to 40.0 mm for turbo 41.0 mm for na.

Also, you can use a turbo head gasket on an na, but not the other way around.

Quite a few differences really. I have heard of guys using the na head, but I would try to use the turbo head on a turbo motor if possible.

Darwantae951

My 2.7 has a "T" stamped on the intake side.

I also had no idea that there was an oil check valve inside the head! Thanks for the info! Anyone care to elaborate on where it is?

mjensen

Mike, that's alot of info! much appreciated, start looking tomorrow...