924Board.org

Andrew NZ · Joined: 22 Jun 2004 Posts: 744 Location: New Zealand

Hi, as most of you know I've had a rotary engine in my 924 for the last 4 or 5 years, so I've lost track of what people are doing to their 924 engines these days!

I have a mate (Terry) who's wanting to build up a new engine for his 924, which his wife uses in classic racing here in New Zealand. They've run it as a completely standard rebuilt engine for the last few years, but are wanting a bit more power now.

Requirements are reliability and probably torque above hp, as the main track they compete at is quite hilly. I've skimmed through some of the posts recently about stroked cranks etc, and wonder if this might be the best option for improved torque? Also interested in the present thoughts about using a turbo head verses the big valve head modification.

We'd appreciate any suggestions people can come with, as well as links to related posts, as the plan is to show this thread to their engine builder when they're ready to go. I usually get my parts through Ideola, so any comments on the bits we can get through him would be greatly appreciated as well.
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Andrew
1977 RX924 race car
12a bridgeport supercharged
www.race4-dcup.co.nz

flosho · Posted: Sat Oct 20, 2012 9:14 am Post subject:

Hi-comp, stroked with efi and ITBs.
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Andrew NZ · Joined: 22 Jun 2004 Posts: 744 Location: New Zealand

Reading through his class rules, EFI might be hard to push through, but everything else is pretty free. Probably have to look at carbs, as I'd imagine the CIS will be a bit restrictive??
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Andrew
1977 RX924 race car
12a bridgeport supercharged
www.race4-dcup.co.nz

the_mad_electrician · Joined: 16 Nov 2009 Posts: 1073 Location: Central Georgia

CIS may be restritive as far as air flow goes but it has better fuel control than a carb/carbs.
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81 924 N/A

2004 Ranger "Edge"

2005 Mazda 6

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

Can you swap to a different Audi motor? Might be a good opportunity to move to a 2.3L 20-valve 5-cylinder Audi motor (non-turbo) Should be about 170hp and can go up from there easier than the 2.0L 4-pot.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

Andrew NZ · Joined: 22 Jun 2004 Posts: 744 Location: New Zealand

932kiwi · Joined: 06 Dec 2009 Posts: 44 Location: Wellington N.Z

I thought Terry already had the turbo head on his car.

(But I have only seen his car once so I'm probably mistaken)

Andrew NZ · Joined: 22 Jun 2004 Posts: 744 Location: New Zealand

Robert Hooper · Joined: 15 Mar 2004 Posts: 70 Location: Christchurch NZ

Hi Andrew,

I used to race my car in Bridgestone class E, engine was blueprinted and balanced.. This made a huge difference, Head was polished and match ported to the intake mainfold, I made 138hp and the flywheel using a standard header..

I still have the head off this car and am not using it if your mate is interested, i would also suggest putting in a piper cam and going to side drafts... I also have a manifold in the garage for this if interested...

Also have a lhd header for the engine, could be modified if wanted to use it...

I am not needing this as converted to 968 engine...

Cheers

Rob
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1982 924 Race Car
1981 931 Road Car

Andrew NZ · Joined: 22 Jun 2004 Posts: 744 Location: New Zealand

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

Andrew
Suggest you look here for some ideas:
http://www.924board.org/viewtopic.php?t=36293

This approach could be used with a lot of the components that Robert mentions in his post. Also, you can build a really nice non-stroked high compression setup using an NA head with US-spec S1 or S2 931 pistons, which are cheap and plentiful. The only drawback is that it doesn't increase displacement because you can only go with 86.5mm and no add'l stroke.

If you want to get some ideas of the different options, take a look at my compression ratio calculator:
Ideola's Cheap-a$$ Long Rod High CR Stroker
OEM Hybrid: NA head with US S1 931 pistons
OEM Hybrid: NA head with US S2 931 pistons
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erstwhile owner of just about every 924 variant ever made

Andrew NZ · Joined: 22 Jun 2004 Posts: 744 Location: New Zealand

john h · Posted: Fri Feb 15, 2013 9:16 am Post subject:

I also have a worked head with a modified cam and I think it's got a piper adjustable cam pulley, that can be purchased.
It came with a 924 that had run it's bearings. Head is OK will check with the previous owner as to what the cam grind is etc. I was going to put it on my daughters engine but decided to leaveher car standard and not sure how the cam would go with the auto
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porscheboy79 · Joined: 25 Oct 2010 Posts: 65 Location: Sydney , Australia

John h
are you interested in selling it to an Aussie if they don't want the head and cam.
Shane.
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79 924. 100kph + wall at Mt Panorama = Gone.

77 924 SPIRIT project for racing.