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Engine for trackday

 
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chris79  



Joined: 29 Jan 2014
Posts: 551
Location: milan

PostPosted: Fri Jul 28, 2017 3:42 am    Post subject: Engine for trackday Reply with quote

At summer end Is time for trackday, now I improved suspension with this parts:

931 swaybars, yellow Bilstein, lowered spring;

I replaced even head gasket and now I would like made some small improvement to engine but whitout open It, any suggestions?
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Porsche 924 2.0 na 125hp (1979) euro
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Alfa Romeo Spider "Duetto" 1.6 104hp (1986) euro
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morghen  



Joined: 21 Jan 2005
Posts: 7874
Location: Romania

PostPosted: Fri Jul 28, 2017 5:47 am    Post subject: Reply with quote

Run race fuel and dial in 10 more degrees of advance.
Depending if its a high speed track or tight one you can advance or retard the cam by one tooth.
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chris79  



Joined: 29 Jan 2014
Posts: 551
Location: milan

PostPosted: Fri Jul 28, 2017 4:30 pm    Post subject: Reply with quote

This is a good free solution, anothers tricks?
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Porsche 924 2.0 na 125hp (1979) euro
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Alfa Romeo Spider "Duetto" 1.6 104hp (1986) euro
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1582
Location: Somerset, UK

PostPosted: Fri Jul 28, 2017 8:53 pm    Post subject: Reply with quote

Should have ported the head, fitted a hot cam and adjustable vernier pulley whilst head was off. Most of the power restrictions are all head related. With tubular headers you should see 145bhp. Maybe more with octane booster and max advance timing.
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1980 931 - forged pistons, Piper cam, CGT turbo, 951 ducted FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife LSD
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Then www.924board.org/viewtopic.php?t=31252
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chris79  



Joined: 29 Jan 2014
Posts: 551
Location: milan

PostPosted: Sat Jul 29, 2017 2:52 am    Post subject: Reply with quote

For now I can't made this modifications, I don't open the head until head gasket burn.

I try with 100 octane fuel and some degrees of advance.

Porting head mean working of exhaust intakes? (1000 $ )
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Porsche 924 2.0 na 125hp (1979) euro
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Alfa Romeo Spider "Duetto" 1.6 104hp (1986) euro
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chris79  



Joined: 29 Jan 2014
Posts: 551
Location: milan

PostPosted: Sat Jul 29, 2017 10:23 pm    Post subject: Reply with quote

And if I modify only my stock cam for hot street use?
Cost is about 200 euro, It is worth doing this change?
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Dutch924-racer  



Joined: 23 Jul 2007
Posts: 1006
Location: The Netherlands

PostPosted: Sun Jul 30, 2017 4:25 pm    Post subject: Reply with quote

I have had a low budget 924 track car for years, lots of fun. Fantastic car in the rain also (much easier than my 931)

What I changed:
- sport rear silincer
- stage one cam
- Audi 5000 throtthel body
- K&N airfilter
- lightened fywheel

The cam gave the most noticeable difference, The open exhaust gives you the feeling you going fast The other things are cheap but I don't think they do much.

Video:

https://youtu.be/27FvQkLQrlM



Other best motifications where new shocks, lower springs and front/ rear swaybars of a 968.
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937 trackday car
Series 2 engine
951S turbo and intercooler
937 DITC
Fast road camshaft
Forge recirculation valve + boost controller
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chris79  



Joined: 29 Jan 2014
Posts: 551
Location: milan

PostPosted: Mon Jul 31, 2017 5:33 am    Post subject: Reply with quote

Very interesting updates, but it's easy to remove the flywell ?
I have already sport setup of suspension and sway, sport filter and open exhaust instead of last muffler.
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nickthompson  



Joined: 26 Mar 2013
Posts: 854
Location: Central Georgia

PostPosted: Mon Jul 31, 2017 11:54 am    Post subject: Reply with quote

One thing that always killed me about the 2.0 is how slowly it revs. You would think a sports car engine would be a little less lazy. The pistons are pretty large and though I've never broken one down enough to take the pistons put I imagine they weigh a ton.
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morghen  



Joined: 21 Jan 2005
Posts: 7874
Location: Romania

PostPosted: Mon Jul 31, 2017 5:20 pm    Post subject: Reply with quote

Actually they don't, they are around 480g with the 944 ones jumping over 500 grams easy. So not too bad for a 86-87mm slug.

Ok today's forged pistons are much lighter shaving 100g off the piston weight of the 924 and I guess today's sports cars only use forged pistons.

The flywheel is a good start to make the engine rev faster, the cam is the next thing in my opinion. Then ignition, TB and fueling.
In US you get much retard of the ignition...in the rest of the world its not so bad actually...I've been driving my 931 with no boost so about US NA power levels and yea its a bit slow revving for a sports car but still moves quite decently if you need it to.
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Ian89C4  



Joined: 01 Apr 2011
Posts: 534
Location: North Carolina

PostPosted: Tue Aug 01, 2017 10:28 am    Post subject: Reply with quote

If you keep the N/A 2.0L above 3500 RPM's she actually revs quite nicely. These cars are meant to be kept high on the cam and sounding like they are going to blow up...but they are actually quite happy.

I've been next to many a gen 1 miata ('80 tech vs. '91 tech and a lot lighter) and the miata didn't out-pull me that much. Now, once we get into 4th the Miata had nothing. This little old fart of a 2.0L has some legs on it. I have even out pulled a late 80's CRX Si at Charlotte Motorspeedway on the back straight...he had nothing for the top end on these old girls.

The motor is a good one for track days. For a beginner that car a great platform as it is very forgiving and won't really bite you. You can also work on your fundamental skills a a driver so that when you do go up in horsepower, you don't run out of talent really quick.

Just my 2 cents.

Cheers!

Ian
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Ian Edgerly
Spiveys Corner, North Carolina

Current:
1981 924 Weissach Race Car ("Serenity")
1980ish 931 ("Alice")
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morghen  



Joined: 21 Jan 2005
Posts: 7874
Location: Romania

PostPosted: Tue Aug 01, 2017 6:01 pm    Post subject: Reply with quote

Ian89C4 wrote:
..so that when you do go up in horsepower, you don't run out of talent really quick.





Can I quote you?
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Ian89C4  



Joined: 01 Apr 2011
Posts: 534
Location: North Carolina

PostPosted: Wed Aug 02, 2017 10:21 am    Post subject: Reply with quote

Absolutely

But I can't claim it my first track instructor said it and it stuck. But it has proven true on many occasions...seen a lot of 5L mustangs keep on going through corners at the end of straights...their reactions not catching up until the just about the tire wall
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Ian Edgerly
Spiveys Corner, North Carolina

Current:
1981 924 Weissach Race Car ("Serenity")
1980ish 931 ("Alice")
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