cylinder head mystery

[BobG]

I need help solving a mystery. Last year I bought a package of parts to build an R5 Alpine head for my R8. The package came with two cylinder heads, the first was a standard Alpine crossflow head but the second one was different. It didn't have the "ridge" at the edge of the combustion chamber. The first photo below shows both heads with the stock Alpine head at the rear. The second photo shows a closeup of the mystery head. It looks very similar to the stock head except for the combustion chamber ridge. Can anyone identify this head?
Bob

 

[Steve Swan]

That's amusing. It seems to be a different casting full stop, some of the webs are different, and the small round indentation is at the opposite end of the head, some French tuners remove the Squish ramp (that's what it is) completely which will not really give any benefit, other than drop the CR if it is an issue. The ramp in the head forces the mixture to the plug at tdc which reduces the chances of detonation and allows leaner mixtures to be used, it is a sort of lean burn idea. It will give better mid range torque than a non squish head, that said if you want to use insane rpm 9000+ then the true hemi is the better design
I did once meet a guy with a Hillman IMP with a 1400 turbo in the back. He said it was a development idea for the A310 which I doubted at the time, but looking back it used a 365 derived box most likely donated from a 310 4 cyl. and it used manifolding that was cast but not R5. It was a neat installation which was not home made. I never saw him or the car again. Maybe an early turbo design which never went into production. Weighing an exhaust valve against a known Atmo one may reveal if it is sodium filled (heavier) and therefor turbo based
Best I can come up with
cheers

 

[Red21]

I would say the head with the squish area is a NA (9.2:1 cr)head and the other is a turbo head (8.8:1 cr)

 

[Steve Swan]

Believe it or not the head castings for atmo and turbo have the same clearance volume. The CR is varied by differences in Piston design, so that's not it . The casting is different which makes it very unusual .

 

[DaveL485]

Believe it or not the head castings for atmo and turbo have the same clearance volume

Same for the 8v J-Series

 

[Red21]

Done some very basic recheck at work and there are two different types listed.
Type A for the 840
Type B for the C6J
Is there any other numbers on the heads?

 

[Steve Swan]

There are basically 3 small Hemis the atmo 840, the turbo C6J and the mid engined turbo C7J. Pretty sure the 840 and C6J use the same casting with different fittings, which probably explains Renault's 2 types
The C7J has a few fundamental differences Cam bearings, oil squirting con-rods and fully floating small ends. I wonder if this is a mid engined R5 turbo head? Personally I have seen loads of the 840 and C6J , but no mid engined stuff (well not in bits anyway) Salv Sacco would know.

 

[Red21]

Possibly, c7j is a injection variants

 

[BobG]

Here is the casting number on the head.


Shortly after I got the 2 heads I had Salv Sacco build a performance cam for my new motor. At that time I asked him which head I should use. He told me to use the one with the squish ramp. I didn't ask him what motor the other came from. I'm wondering what value the non-squish head has, if any. I suppose it could be used to build a DIY turbo motor (since it has more volume=lower compression) or an atmo motor using higher compression pistons.
Bob

 

[Red21]

Here are some PDFs of cylinder head part parts slides from both Gordine NA & turbo plus T2.
All my old tech docs are in storage now but I am planning to dump some more stuff there over the weekend so I will see what I can find.

 

[Red21]

Done some searching of some document I have in storage and was unable to identify the part number, but I do think the head with no squish area is a C7J head and potentially from a Gp B+ T2
Have a look at the attached pictures & pdf extract and see if it could be??

 

[BobG]

The photo you sent definitely looks like my head. Anybody rebuilding a T2 beast and in need of a replacement head?

 

[Steve Swan]

Think you have cracked it ! only unexplained thing is the size of the water holes, turbo are usually bigger than ATMO to allow increased flow

 

[Red21]

Think you have cracked it ! only unexplained thing is the size of the water holes, turbo are usually bigger than ATMO to allow increased flow

I hope I haven't cracked it or it would be a useless head
With the water holes it's the gasket that would be the flow regulator as it is easier to change design and to have a flow difference between the two ends.
The only two document that I couldn't find is for a original R8 R Gordini but I think they had more or less the same engine as a regular R8 G with slight chassis /exterior changes?
And for A110 1400s,
Then again we could all be wrong and its a one off head modified to look like a factory cast head

 

[Steve Swan]

That's a Die-cast head from an iron mould, you can tell by the surface finish, and Renault being Renault nothing is as it seems. 1100G and 1300G heads have different waterway drillings that is one way of identifying what you have. The later 5 based heads also have different drillings from Atmo to Turbo, as I re drilled my Atmo head to turbo sizes, thing is it was 20 years ago and I cannot remember the sizes offhand, I am positive the Turbo motors drillings were 1.5mm larger, like 8.5mm up to 10mm

 

[DrKd]

 

[Adey]

some nice info popping up in here

 

[DrKd]

I used a 12.5mm bit then reamed to 13mm - they're very thin

 

[DrKd]

Maxi Block