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1980 931 European vs US

 
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doolie72  



Joined: 01 Dec 2018
Posts: 27
Location: California, USA

PostPosted: Mon Jan 27, 2020 3:39 pm    Post subject: 1980 931 European vs US Reply with quote

Can anyone clarify where the extra power comes from in a 1980 European spec 931? Iíve searched around and discovered that for 1980 the compression ratio was 7.5 for both euro and US, so assuming it might be down to one of all of the following:
Timing (for higher octane fuels)
Boost
Lack of catalytic converter?

Thanks
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bureau13  



Joined: 07 Sep 2017
Posts: 252
Location: South Florida

PostPosted: Tue Jan 28, 2020 12:36 am    Post subject: Re: 1980 931 European vs US Reply with quote

My understanding is that the bulk of it is due to increased boost, but I don't know that they didn't make other changes at the same time. They may well have pulled some timing to make that increased boost safer?

doolie72 wrote:
Can anyone clarify where the extra power comes from in a 1980 European spec 931? Iíve searched around and discovered that for 1980 the compression ratio was 7.5 for both euro and US, so assuming it might be down to one of all of the following:
Timing (for higher octane fuels)
Boost
Lack of catalytic converter?

Thanks

_________________
-----------------------------------------
1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)

Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen)
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1973
Location: Somerset, UK

PostPosted: Tue Jan 28, 2020 1:29 am    Post subject: Re: 1980 931 European vs US Reply with quote

bureau13 wrote:
My understanding is that the bulk of it is due to increased boost, but I don't know that they didn't make other changes at the same time. They may well have pulled some timing to make that increased boost safer?

doolie72 wrote:
Can anyone clarify where the extra power comes from in a 1980 European spec 931? Iíve searched around and discovered that for 1980 the compression ratio was 7.5 for both euro and US, so assuming it might be down to one of all of the following:
Timing (for higher octane fuels)
Boost
Lack of catalytic converter?

Thanks


Incorrect. The boost is the same. Itís a combo of compression ratio, turbo and ignition differences. 7bhp on paper does not reflect on the road that itís quicker. Just delivers power differently to series 1. Not one or the other is better or worse. Just different.
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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
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Cťdric  



Joined: 27 Aug 2004
Posts: 1975
Location: Sweden

PostPosted: Tue Jan 28, 2020 2:15 am    Post subject: Reply with quote

Steve, i think you are mixing up the s1 s2 thread with this us vs row discussion

Its both boost and timing, and also the cat if course. So pretty easy to get it back up to row specifications
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bureau13  



Joined: 07 Sep 2017
Posts: 252
Location: South Florida

PostPosted: Tue Jan 28, 2020 7:17 am    Post subject: Re: 1980 931 European vs US Reply with quote

Unless everything I've read about it is wrong, the Euro car made ~10 psi and the US version was closer to 6. That's a significant difference.

Carrera RSR wrote:
bureau13 wrote:
My understanding is that the bulk of it is due to increased boost, but I don't know that they didn't make other changes at the same time. They may well have pulled some timing to make that increased boost safer?

doolie72 wrote:
Can anyone clarify where the extra power comes from in a 1980 European spec 931? Iíve searched around and discovered that for 1980 the compression ratio was 7.5 for both euro and US, so assuming it might be down to one of all of the following:
Timing (for higher octane fuels)
Boost
Lack of catalytic converter?

Thanks


Incorrect. The boost is the same. Itís a combo of compression ratio, turbo and ignition differences. 7bhp on paper does not reflect on the road that itís quicker. Just delivers power differently to series 1. Not one or the other is better or worse. Just different.

_________________
-----------------------------------------
1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)

Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen)
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1973
Location: Somerset, UK

PostPosted: Tue Jan 28, 2020 8:10 am    Post subject: Reply with quote

Cťdric wrote:
Steve, i think you are mixing up the s1 s2 thread with this us vs row discussion

Its both boost and timing, and also the cat if course. So pretty easy to get it back up to row specifications


Yep. You are right. Travelling Germany and posting on the fly
_________________
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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Mike9311  



Joined: 14 Dec 2004
Posts: 834
Location: Chicago-ish

PostPosted: Wed Mar 11, 2020 2:16 am    Post subject: Reply with quote

Sorry so late to this topic.... This I know for sure since I have one

1980 USA has the larger 2664 Compressor wheel and smaller 4.10 Turbine housing. (1981 and '82 USA received the 2660 with 4.10)

Pretty sure the Euro 1980 had the small 'old school design' 2470 Compressor and larger 6.10 turbine housing.


I know its been said its easy to find the 2664 here in USA but not so much anymore. It was only 1980.
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1980 931 since 1989
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