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16v head swap? lets work it out!
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morghen  



Joined: 21 Jan 2005
Posts: 8199
Location: Romania

PostPosted: Thu Sep 07, 2017 4:37 pm    Post subject: Reply with quote

custom cams can be made, is that head cutting feasible? do the spacing and bores work? how about the stuts?
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Paulyy  



Joined: 05 May 2014
Posts: 87
Location: Melbourne

PostPosted: Mon Sep 11, 2017 6:37 pm    Post subject: Reply with quote

morghen wrote:
custom cams can be made, is that head cutting feasible? do the spacing and bores work? how about the stuts?


Im actually not sure which 20v head we're talking about. The 5 cylinder or the 4 cylinder??

I can't find info in either.

Cutting and welding a 5 cylinder head into 4? i dont think it's really feasible if everything lined it. maybe, depends on head design.
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morghen  



Joined: 21 Jan 2005
Posts: 8199
Location: Romania

PostPosted: Mon Sep 11, 2017 7:47 pm    Post subject: Reply with quote

I was talking about taking a 5cyl audi head and cutting it to fit the 924 if the spacing is ok and the head studs position are an advantage.
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Paulyy  



Joined: 05 May 2014
Posts: 87
Location: Melbourne

PostPosted: Mon Sep 11, 2017 7:54 pm    Post subject: Reply with quote

The 07K head? i dont think so. it'll require to much work to even consider it. Give it a google search to see how it looks.
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morghen  



Joined: 21 Jan 2005
Posts: 8199
Location: Romania

PostPosted: Mon Sep 11, 2017 8:32 pm    Post subject: Reply with quote

meh, I believe you, I was just talking out of my ass

One could CNC one I guess....or CNC a head and block in one piece and run 10bar of boost making 5000hp
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Paulyy  



Joined: 05 May 2014
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Location: Melbourne

PostPosted: Mon Sep 11, 2017 8:43 pm    Post subject: Reply with quote

hahaha!

Trust me, if i had a 5 axis, i would be drawing up a head by now.

I only have a small 3 axis cnc router.

Im looking at combustion chambers, if its worth cutting into a n/a head. even if it's 5mm deep. i did make a thread about it just before.

I know the 931 head has it, and i did see someone modify it to some extent.
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v2rocket_aka944  



Joined: 05 Jan 2009
Posts: 40
Location: San Diego, CA

PostPosted: Tue Sep 12, 2017 6:50 am    Post subject: Reply with quote

Paulyy wrote:
The 07K head? i dont think so. it'll require to much work to even consider it. Give it a google search to see how it looks.


not the o7K...
i meant the old 20V "AAN" 5 cylinder of the 1980s rally cars...
2.2 or 2.3L usually, found in the audi Quattro coupes, some sedans, etc.

the 924 I-4 shares a bellhousing pattern with that 5 cylinder which is how the 5 cylinder bolts up easily enough.

could the 924 engine be derived/related to the Audi 5?
or just coincidence of bolt pattern?
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Paul  



Joined: 02 Nov 2002
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Location: Southeast Wisconsin

PostPosted: Wed Sep 13, 2017 1:09 pm    Post subject: Reply with quote

Porsche Audi and VW were the same company in years past, so they were just using what was in their supply chain.
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nickthompson  



Joined: 26 Mar 2013
Posts: 873
Location: Central Georgia

PostPosted: Wed Sep 13, 2017 5:47 pm    Post subject: Reply with quote

v2rocket_aka944 wrote:
Paulyy wrote:
The 07K head? i dont think so. it'll require to much work to even consider it. Give it a google search to see how it looks.


not the o7K...
i meant the old 20V "AAN" 5 cylinder of the 1980s rally cars...
2.2 or 2.3L usually, found in the audi Quattro coupes, some sedans, etc.

the 924 I-4 shares a bellhousing pattern with that 5 cylinder which is how the 5 cylinder bolts up easily enough.

could the 924 engine be derived/related to the Audi 5?
or just coincidence of bolt pattern?


The old Audi i5s have a much smaller bore spacing than the original 2.0
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Euro924S2  



Joined: 06 Mar 2008
Posts: 183
Location: UK

PostPosted: Thu Dec 05, 2019 7:32 am    Post subject: Reply with quote

An old thread to resurrect but Iím in the process of trying to build a 2.0L 16v engine. Block is standard 924, pistons are Vw flat tops to bring the compression up and the head is from a Ford Duratec engine. The cylinder spacing is 95.5mm compared to 95mm on the 924 but hopefully thatís not an issue. There are LOTS of issues including head bolt location, itís a lubricated cam chain instead of belt and the oil supply/return and water galleries area all wrong, but importantly it has 16valves and massive ports so if I can get it to work it should be a worthwhile upgrade....

Full details here on the UK site but you need to sign up to be a forum member to view I think.

https://porsche924.co.uk/forum/viewtopic.php?f=122&t=33648
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Mike9311  



Joined: 14 Dec 2004
Posts: 873
Location: Chicago-ish

PostPosted: Thu Feb 27, 2020 4:14 am    Post subject: Reply with quote

The hardest part with this project is identifying cylinder spacing for any cylinder head. I'll have to register for the other forum to keep up with your progress

I'm still too busy working on the 2 valve head project before moving to the 16
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Euro924S2  



Joined: 06 Mar 2008
Posts: 183
Location: UK

PostPosted: Thu Feb 27, 2020 7:42 am    Post subject: Reply with quote

True, I was lucky Rich H did the hard work for me there. The head is now bolted to the block and cylinder spacing isnít an issue. The oil and water galleries are in theory sorted (although not tested I donít imagine any major issues). Oil feed to the head is just a case of threading a union into the block. The remaining jobs are the cam sprockets. I hoped to use 2 x 924 pulleys so the crank could remain stock, but they are too large to clear each other with the Duratec cam shaft spacing. Mx5 (Miata) pulleys will work nicely though (I had a pair of verniers for that engine on the shelf!) so Iíve bought a Mazda crank pulley to keep the 2:1 ratio and will machine that to fit the 924 crank. I can hen attempt a start by running it with all the Ford wiring harness, injectors, eCU etc on the engine stand and check there are no glaring errors before spending the cash having the block machined and head rebuild properly.
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UK spec '83 N/A with 931 motor with Eaton MP62 'charger @ 15psi. EFI - 565cc inj. Standalone Adaptronic ECU. 951 FMIC. Ally rad. Twin throttle. Recirc valve. Custom manifolds and CAI. 232bhp
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Mike9311  



Joined: 14 Dec 2004
Posts: 873
Location: Chicago-ish

PostPosted: Thu Feb 27, 2020 7:48 am    Post subject: Reply with quote

Wow, its finally going to be done by someone. Very cool

I keep looking for a Volvo twin cam head since it is rumored to be Porsche
or Cosworth designed but they are hard to come by

Your path may just be the path!
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1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA M650 Herausnehmbares Dach
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car
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Euro924S2  



Joined: 06 Mar 2008
Posts: 183
Location: UK

PostPosted: Thu Feb 27, 2020 7:56 am    Post subject: Reply with quote

Itís been both simple and a nightmare! The actual conversion is not that hard, but Iíve spent probably 100 hours welding and machining the new head bolt holes. The HG side is easy because access isnít a problem. The cam shaft side is a major challenge. Itís not helped because the cast ally has been bathed in oil for years so contamination is a major problem. Pressure testing the water jacket reveals the porous welds which needed grinding out and re-welding over and over and over. They then have to have a final grind flat to seat the nuts - that exposes porosity and the cycle of weld and grind starts again. Iíve learned a lot about welding, machining and how much access I should have created from day one instead of gradually improving. Iíve now done so much work on the galleries etc Iím loathed to start again, although had I have done that 50 hours ago it might well have been much quicker (and cheaper in Argon!) - oh yeah, I also bought a new, more powerful Tig which helped!!

The rest of the machine work is more straightforward and helped even more by having a CCN mill and lathe at home. Time is the biggest problem so I fear this engine wonít get in my car until this coming winter.
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UK spec '83 N/A with 931 motor with Eaton MP62 'charger @ 15psi. EFI - 565cc inj. Standalone Adaptronic ECU. 951 FMIC. Ally rad. Twin throttle. Recirc valve. Custom manifolds and CAI. 232bhp
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Euro924S2  



Joined: 06 Mar 2008
Posts: 183
Location: UK

PostPosted: Thu Feb 27, 2020 7:58 am    Post subject: Reply with quote

The major benefit on the Duratec is the head was £75 because they are so common and no-one wants them. The bottom ends are not really rebuildable apparently so an engine issue is just a swap for a used one or buy new Iíd flush with cash. So lots of heads are available cheaply.
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