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What's the horsepower difference between US and Euro spec
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Ohio-924  



Joined: 09 Jan 2021
Posts: 1
Location: Ohio

PostPosted: Sat Jan 09, 2021 9:02 am    Post subject: What's the horsepower difference between US and Euro spec Reply with quote

I have 1977 924 and I want to bump up the horsepower without having to add forced induction or something along those lines. Something to note as well is that my 924 hasn't ran since 2007 and has ran a total of maybe 5 times and only ran for about 10 or so seconds at a time. I heard there's a difference between a Euro spec 924 and a US spec 924, is there?
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924-76  



Joined: 05 Jun 2006
Posts: 1418
Location: Ontario, Canada

PostPosted: Sat Jan 09, 2021 12:02 pm    Post subject: Reply with quote

Yes
Euro 924, 125hp
US 77 924, 95hp

The main difference are the pistons which result in a different compression ratio. I believe there are other small difference which I can't remember at the moment.
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1976 924 N/A ROW SOLD
1980 931S
1981 931 Part car RIP
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Fifty50Plus  



Joined: 28 Feb 2008
Posts: 1138
Location: Washington DC area

PostPosted: Sat Jan 09, 2021 12:31 pm    Post subject: Reply with quote

There is also a difference in the crankshaft. The early 924s had different sized bearings.
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1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car
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MikeJinCO  



Joined: 08 Jun 2010
Posts: 971
Location: Maysville, Colorado

PostPosted: Sat Jan 09, 2021 1:10 pm    Post subject: Reply with quote

The 77.5 model got bigger intake valves, 40mm vs 38mm, a higher compression ratio from 8.5 vs 8.0 and a slightly different camshaft with more duration. They also changed the torsion bar spring plates from the one piece Super Beetle type to adjustable. They kept that cam for the duration of the model run including the turbo's. They timing was also retarded probably for pollution compliance.

My opinion is that because the airflow in the head basically stalls at .400 lift least expensive way to get more power is to get longer duration cam in the 265-275 range with the normal lift(.470+-) and then advance the timing quite a bit. Track car is 41 degrees at 3000rpm, I going to play with that on my street car in the spring. Idle might suffer a bit. Stock dimension cams are available from Newman Cams, Piper Cams and Kent Cams in the UK and prices are in the $400 range. All the cams in this country are regrinds meaning valve train modifications. I got a semi-race cam from Cat Cams in Netherlands, delivery was in about 4 weeks and the shipping was in 3 days and shipping cost $40.
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Mike
Poco a Poco, #033 '78 Vintage racer, SCCA Dp-81
'77 924
cricketdesigns.com
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Mike9311  



Joined: 14 Dec 2004
Posts: 993
Location: Chicago-ish

PostPosted: Sun Jan 10, 2021 3:29 am    Post subject: Reply with quote

Mike

Have you tried epoxy in your head testing? I believe you built a flow bench right? Just curious

Mike
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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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Carrera RSR  



Joined: 08 Jan 2010
Posts: 2111
Location: Somerset, UK

PostPosted: Sun Jan 10, 2021 4:20 am    Post subject: Reply with quote

Not too hard to get 145bhp out of a euro NA. The U.K. racers do this off the bat and they have regulation limitations to what they can do to the engine.
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252
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Fifty50Plus  



Joined: 28 Feb 2008
Posts: 1138
Location: Washington DC area

PostPosted: Sun Jan 10, 2021 6:46 am    Post subject: Reply with quote

Carrera, I'd like to see what the UK rules are for the 145 hp from an NA engine. Can you direct me to a set of the rules so I can compare to my SCCA rules. I'm getting a bit over 130 hp with the stock cam and compression ratio. I use 41 degrees timing and the engine runs out of torque (not revs) at 6500.
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1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car
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Karlio  



Joined: 17 Nov 2019
Posts: 15
Location: UK

PostPosted: Sun Jan 10, 2021 8:20 am    Post subject: Reply with quote

Fifty50Plus wrote:
Carrera, I'd like to see what the UK rules are for the 145 hp from an NA engine. Can you direct me to a set of the rules so I can compare to my SCCA rules. I'm getting a bit over 130 hp with the stock cam and compression ratio. I use 41 degrees timing and the engine runs out of torque (not revs) at 6500.



Piper cam ultimate(specs on the piper website) , 87.5mm euro pistons, crank scraper, audi 100/golf/neuspeed/924 turbo throttle body, 'modified' wur, k&n panel air filter, a proper stainless exhaust, 99 octane fuel, solid lifters.

No porting,no lightened flywheel. Standard ignition set up, standard fuel dizzy set up.
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Fifty50Plus  



Joined: 28 Feb 2008
Posts: 1138
Location: Washington DC area

PostPosted: Sun Jan 10, 2021 8:27 am    Post subject: Reply with quote

Ah, thanks. I'm not allowed the Piper cam nor the Neuspeed throttle body. Everything else I've done. I modify the fuel via the frequency valve to produce 12.8 CO (max power on the dyno) on my wideband meter.
_________________
1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car
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Karlio  



Joined: 17 Nov 2019
Posts: 15
Location: UK

PostPosted: Sun Jan 10, 2021 8:48 am    Post subject: Reply with quote

Can you deck the block by 1mm and can you cut down the valve guides.?
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Karlio  



Joined: 17 Nov 2019
Posts: 15
Location: UK

PostPosted: Sun Jan 10, 2021 9:10 am    Post subject: Reply with quote

We were limited by regs to143 hp and 1000kg with driver post race. 15 inch wheels, gaz or leda shocks, solid front discs, rear drums.
You can get more hp by advancing the timing but that causes HG issues as you are aware

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Fifty50Plus  



Joined: 28 Feb 2008
Posts: 1138
Location: Washington DC area

PostPosted: Sun Jan 10, 2021 10:09 am    Post subject: Reply with quote

We are limited to 1/2 point increase in compression ratio either with different piston or cutting the block. I went with Diamond pistons to get the compression bump and 1mm increase in piston diameter. I do run it at 41 degrees advanced as that showed optimum power at full chat on the dyno.
The engine is the bad news in my class (oh yes, I have to run stock gearbox ratios) but I'm allowed the 944 brakes; vented rotors front and rear with 15 inch wheels. I've raced 911s, 356s, VWs, BMWs, M-Benzs and an Acura Type R and the 924 is the best neutral handling and stopping car I've ever had. That's the reason I do so well in the class I run (Volvo, BMW, Alfa, VW, Honda, Mazda). But most of them pull me on the straights due to weight and HP. Braking and cornering are the 924 strengths as well as aerodynamics on really long courses. I'm required to weigh 2495 lbs with driver coming in off track while most of my competitors are 100-200 lbs lighter.

PS: stock head, intake runners, valves and guides. No work allowed.
_________________
1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car
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Karlio  



Joined: 17 Nov 2019
Posts: 15
Location: UK

PostPosted: Sun Jan 10, 2021 10:16 am    Post subject: Reply with quote

That is one heavy car, proper disadvantage.
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CÚdric  



Joined: 27 Aug 2004
Posts: 2080
Location: Sweden

PostPosted: Sun Jan 10, 2021 8:25 pm    Post subject: Reply with quote

Fifty50Plus wrote:
We are limited to 1/2 point increase in compression ratio either with different piston or cutting the block. I went with Diamond pistons to get the compression bump and 1mm increase in piston diameter. I do run it at 41 degrees advanced as that showed optimum power at full chat on the dyno.
The engine is the bad news in my class (oh yes, I have to run stock gearbox ratios) but I'm allowed the 944 brakes; vented rotors front and rear with 15 inch wheels. I've raced 911s, 356s, VWs, BMWs, M-Benzs and an Acura Type R and the 924 is the best neutral handling and stopping car I've ever had. That's the reason I do so well in the class I run (Volvo, BMW, Alfa, VW, Honda, Mazda). But most of them pull me on the straights due to weight and HP. Braking and cornering are the 924 strengths as well as aerodynamics on really long courses. I'm required to weigh 2495 lbs with driver coming in off track while most of my competitors are 100-200 lbs lighter.

PS: stock head, intake runners, valves and guides. No work allowed.


Interesting, why are your required weight higher?

Are you allowed any aerodynamic modifications? Like building an undertray, or maybe using the 944 rear hatch/spoiler? It would give you some more top end speed without more hp.
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Fifty50Plus  



Joined: 28 Feb 2008
Posts: 1138
Location: Washington DC area

PostPosted: Mon Jan 11, 2021 11:58 am    Post subject: Reply with quote

We are allowed to use the 924 Turbo tail but not the 944 version. I also retained the front engine undertray to aid in cooling but don't think it does much else.
SCCA does not appreciate Porsches winning any races since Porsche does not provide sponsorship to Corporate SCCA HQ unlike Mazda, Nissan, Toyota, BMW, and a few others. In the '80s, I was dominating D-Prod with a 911 at a realistic weight. In 2000, I started building a 2.4 911 based on it finally being approved for Improved Touring at 2200 lbs (factory weight). When the club heard that I was building another Porsche, they changed the rules and added 300 lbs to the minimum weight before I even hit the track. Datsun 240Zs were the dominant car (Nissan giving money to the club office) at 2300 lbs. After I finally got my car built and dialed in, I was 1/2 sec slower than the winning Datsuns. The 300 lbs SCCA gave me made a big difference in my lap times.
So I sold the 911 and built my first 924 after seeing what Vaughan Scott did with his car at Road Atlanta (long track, heavy braking needed). It's a great car but could use a few more horses on the shorter tracks.
_________________
1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car
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