6.0 cylinder heads on 5.3 HE engine

Ok gotya. I was setting up when I took that pic, I had every valve in both heads leaking. Even with a leak it’s impossible to CC the chambers.

Here is a pic of CCing and during adjusting chambers to be equal

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So, your objective with these mods was to do away with the H.E. swirl function and optimize flow instead? Did you regrind the cam for a bunch more lift while you were at it?

No cams are stock, I discussed this with Norman and his recommendation was to keep the cams stock as I will be limiting RPM to 6000 due to the 4L60e trans. With the 6.7L I should have 400odd HP and a heap of torque.

I have kept the quench area about the same and the piston will be 0.040" closer to the head than the stock HE. So I should have more turbulence in the chamber as the piston approaches TDC, but less turbulence as the piston sucks the charge in. This is why I went with a finer mist injector.

All sharp edges are gone and the spark plug de-shrouded. Most of the chamber work was done with increasing low lift flow as a priority.

Other changes are 12 flow matched X Type Denso injectors, these are 12 hole and provide much finer atomisation. Megasquirt ECU, intake manifolds were matched to the port entry and the injector bump removed and exhaust manifolds have been reworked to remove all of the machining marks.

Here are a couple of before and after pics, notice the exposed threads on the bottom of the exhaust chamber, these will get hot and cause detonation. So will the sharp edges of the chamber.

All the machining and casting marks have been removed.

hi warren , any suggested date when she fires UP??

then comes the tuning, and dyno time!


Hi is 29cc the stock combustion chamber size on the 6.0?

There is a post in the bowels of Jag Lovers from Bywater stating that the 6.0 was 11.2 : 1. Most other literature says 11:1 but that might just be rounding. I have found that much of the accepted data that is commonly available doesn’t stand up to scrutiny. Just a series of Wikipedia Chinese whispers.

I think Richard Dowling posted some time ago his measurements on the HE.

Someone posted that the 5.3 piston had between 25.2 and 25.6ml.

I think you also need to account for the top ring land on your pistons, as this adds to the chamber volume. But if anything, that will reduce the CR even further. And who really knows how thick a compressed head gasket is. I have seen a figure of 1.04mm which sounds like someone has tried hard to get an exact measurement, but again, who knows under what conditions. I tried to calc it all with a CAD model, and it was surprising how every little detail changed the result.

This from Norman Lutz posted back in 2011:

"Kirbert, only 25cc of the combustion volume is in the piston, the other 40cc is in the cylindrical space created by the piston being 3.8mm down the bore.

So even if you put a flat top piston in, the CR will only be 15.6:1.

If you had a piston that came up to the top of the block you wouldn’t be able to open the valves.

Consequently that is why you could use a FH piston with 0.45mm machined of the top in a 6L.

8.5mm /2 = 4.25 which is 0.45mm/0.022in. more than the 3.8mm that is available in a FH engine."

Original thread was “Time for the V12’s engine build to start…” back in Dec 2010 or there abouts.

I’m assuming that is a reference to the stroke on the 6.0L being 8.5mm more than on the 5.3L