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Curb Weight and Power
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DZGunner  



Joined: 18 Nov 2014
Posts: 129
Location: Great white north

PostPosted: Tue Mar 24, 2015 2:10 pm    Post subject: Curb Weight and Power Reply with quote

What's the lowest you guys have been able to, or have heard of getting the curb weight of 931's down to.

I used a weigh station down the street from my house and got 2470lbs.

I don't know how accurate the scale is but that seems about right with all the stuff I've pulled out. My owner's manual says the stock weight is 2822lbs. So i managed to cut 352lbs of: AC, carpets, heating, rear seats (upper only), Evap system, Radio (with antenna).

As for the power; My understanding is that the 80 and below turbos made 158HP? and then the S2 setup made more, but idk if the S2's made 170 or if that was the euro models.

I'm putting a MBC in my 80 and was wondering what my power figures might look like with a stock, healthy engine at 9-10 PSI.

Thanks guys.
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Grenadiers  



Joined: 20 Feb 2007
Posts: 3224
Location: Nelson, WI & Prescott, AZ

PostPosted: Wed Mar 25, 2015 1:46 am    Post subject: Reply with quote

I'd reckon the scale is a bit off! Those pulled items don't seem to add up to 352 pounds. In any case, I've had both engines in my CGT clone, and couldn't tell the difference by the seat of my pants. I also have the top mounted intercooler, and a manual boost gauge, set around 10-12psi, and a Euro turbo-charger. Rebuilding the Series II engine this summer, for one last shot at durability for the track car.
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Rasta Monsta  



Joined: 12 Jul 2006
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Location: PacNW

PostPosted: Wed Mar 25, 2015 2:31 am    Post subject: Reply with quote

My 924S race car is about 2400 with cage. I suppose the engine might be a bit lighter than the 931.

Not sure I would have deleted the defroster.
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Raceboy  



Joined: 01 Mar 2004
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Location: Estonia, Europe

PostPosted: Wed Mar 25, 2015 3:08 am    Post subject: Reply with quote

2.5 engine is not lighter than 931 engine even with turbo and CIS stuff combined.
They are pretty much the same, but you can get 931 one a bit lighter when going EFI and dumping CIS.
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morghen  



Joined: 21 Jan 2005
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Location: Romania

PostPosted: Wed Mar 25, 2015 4:08 am    Post subject: Reply with quote

I've scaled my gts wannabe 924 at 1170kg with a decent amount of fuel in it.

Euro model S1 makes 170hp and the S2 euro model makes 177, both no intercooler. Us models might make less power.
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fiat22turbo  



Joined: 18 Jan 2006
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Location: Portland, OR

PostPosted: Wed Mar 25, 2015 5:14 am    Post subject: Reply with quote

morghen wrote:
I've scaled my gts wannabe 924 at 1170kg with a decent amount of fuel in it.


That's 2579.408 lbs for those that aren't metrically inclined.
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ideola  



Joined: 01 Oct 2004
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Location: Woodstock IL

PostPosted: Wed Mar 25, 2015 5:24 am    Post subject: Reply with quote

When we corner-weighted the Club Sport, it was dead nuts on 2500# with half a tank of gas. That's with some serious lightening, and a little weight added back in (bolt-in Redline style rollbar and top mount charge cooler setup).

US BHP figures are 150 and 158 respectively according to tech specs booklet. IMO, almost all of the power difference between US and Euro is due to the half-point less of compression and timing. I don't think much is attributable to emissions equipment as is commonly cited.
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Carrera RSR  



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PostPosted: Wed Mar 25, 2015 7:23 am    Post subject: Reply with quote

Corner weighted at 1140kg (2510lbs) with lots removed but big items added back like a full cage, half tank of fuel, 951 IC, bigger rad = more coolant etc. feels quite lively with circa 220+bhp
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DZGunner  



Joined: 18 Nov 2014
Posts: 129
Location: Great white north

PostPosted: Wed Mar 25, 2015 2:13 pm    Post subject: Reply with quote

ideola wrote:
When we corner-weighted the Club Sport, it was dead nuts on 2500# with half a tank of gas. That's with some serious lightening, and a little weight added back in (bolt-in Redline style rollbar and top mount charge cooler setup).

US BHP figures are 150 and 158 respectively according to tech specs booklet. IMO, almost all of the power difference between US and Euro is due to the half-point less of compression and timing. I don't think much is attributable to emissions equipment as is commonly cited.


Whats the timing set at for euro models?
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Rasta Monsta  



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PostPosted: Wed Mar 25, 2015 4:12 pm    Post subject: Reply with quote

Raceboy wrote:
2.5 engine is not lighter than 931 engine even with turbo and CIS stuff combined.


Can't imagine how a cast iron 2.0 block is anywhere near the weight of an all alloy 2.5. Yes, it has two balance shafts, but it doesn't even have main bearing caps and the crank girdle weighs less than the Sunday paper!
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Raceboy  



Joined: 01 Mar 2004
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PostPosted: Wed Mar 25, 2015 5:11 pm    Post subject: Reply with quote

I have both blocks sitting side by side in the garage, it is not a guess.
2.5liter block is much bigger (=much more material) and 2.5 liter crank weighs much more than 2.0liter crank.
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Cédric  



Joined: 27 Aug 2004
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Location: Sweden

PostPosted: Wed Mar 25, 2015 5:14 pm    Post subject: Reply with quote

http://utzon.se/information/My931.html

895kg = 1973lbs , thats a light car. But it takes som dedication.
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Shurick  



Joined: 15 May 2005
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Location: Russia, Moscow.

PostPosted: Wed Mar 25, 2015 5:35 pm    Post subject: Reply with quote

Rasta Monsta wrote:
Raceboy wrote:
2.5 engine is not lighter than 931 engine even with turbo and CIS stuff combined.


Can't imagine how a cast iron 2.0 block is anywhere near the weight of an all alloy 2.5. Yes, it has two balance shafts, but it doesn't even have main bearing caps and the crank girdle weighs less than the Sunday paper!

Porsche 924 tech specs lists dry weight for a 931 engines: 165 kg.
Porsche 944 workshop manual lists dry weight for 8v 944 engines: 166 kg.
I was shocked too.

BTW, euro 924 engine (XK) weights only 136 kg.
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morghen  



Joined: 21 Jan 2005
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PostPosted: Wed Mar 25, 2015 8:57 pm    Post subject: Reply with quote

hmm, here i was thinking i have a light 924 when actually its one of the fattest
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Rasta Monsta  



Joined: 12 Jul 2006
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PostPosted: Thu Mar 26, 2015 3:05 am    Post subject: Reply with quote

Raceboy wrote:
2.5 liter crank weighs much more than 2.0liter crank.


Certainly true. . .the crank is beastly.
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