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Dutch924-racer · Joined: 23 Jul 2007 Posts: 1081 Location: The Netherlands

Is there any difference between the S1 and S2 931 cylinderhead ? So are they interchangeable ?
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Smoothie · Posted: Sun Dec 06, 2009 5:14 am Post subject:

Was never in a situation to compare the two, but one minor item comes to mind. The later one might have the hole drilled for the turbo oiler breather, while the earlier one may not..? Easy to fix either way - either drill the hole/s, or install a block-off plate..

Other than that, I'm real sure they're the same and interchangable.
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Grenadiers · Posted: Sun Dec 06, 2009 5:41 am Post subject:

Here's the shot of the Series I Euro head I have. Note the right side where there are two threaded holes. Not a block-off plate either.

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Grenadiers · Posted: Sun Dec 06, 2009 5:46 am Post subject:

But then, on Spike, also a 1980, you can see there is the turbo breather.

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ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

Many S1 heads were either already built with the breather update or may have been taken back to the dealer and fixed later. I have only seen one S1 931 head aside from Dave's photo above that did NOT have the breather update port drilled. Aside from that, I am not aware of any other differences between the S1 & S2 head.
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Cedric · Joined: 27 Aug 2004 Posts: 2809 Location: Sweden

I have the "uppgraded" pipe to on my s1 motor (sits on the shellf at the moment in favour of a s2 engine). It also has the uppgraded manifold. Could it be that the late 1980s models got the uppgrades from factory?
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ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

Rich H · Posted: Sun Dec 06, 2009 10:52 am Post subject:

I'm sure I saw a leaflet issued to dealers to add the breather mod that included drilling the head
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Smoothie · Posted: Sun Dec 06, 2009 11:00 am Post subject:

More on the turbo breather updates here - http://www.924board.org/viewtopic.php?t=10536
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

jessy1984 · Joined: 09 Jun 2009 Posts: 82 Location: belgium

they are both the same
just looked in pet same part number
only like mentiond here there's a modification for the turbo breather
if its not there just drill a hole in it

McGyver · Posted: Tue Dec 08, 2009 7:05 am Post subject:

I don't have this breather update too in my 931' 79 cylinder head. But I have plan to drill that hole and use it later in my engine rebuild project.
Cylinder head part number is: 931 104 301 3R
It's taken from 924 Turbo series 1 - 1979

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moone924 · Joined: 05 Feb 2003 Posts: 868 Location: Douglas Wyoming

I guess my late '82 931 has a early head on it, as it looks like the euro series one head Grenadiers has, with no breather.
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Paul · Posted: Sat Dec 19, 2009 10:40 am Post subject:

Spike has a series 1 US head.
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Dutch924-racer · Joined: 23 Jul 2007 Posts: 1081 Location: The Netherlands

thanks for the replies, I just bought a s2 head. It does have the hole in it.

My other s2 had didn't have the hol in it. But I drilled it in myself and made the modification pipe.
_________________
937 trackday car
Series 2 engine
951S turbo and intercooler
Fast road camshaft
Forge recirculation valve + boost controller

pelican13 · Joined: 21 Sep 2009 Posts: 22 Location: Provence ,FRANCE

I have an euro 931 of 1982 , CN100539 , there is no breather hole in the cyinderhead.