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juno

Just bought a 924 turbo. Runs well, very nice and all, but I'm getting about 22 mpg from average driving. Is there anything I can do myself to try and troubleshoot it as I really can't afford garage prices right now..

Racing · Joined: 27 Apr 2004 Posts: 374

Yeah.
1/buy a haynes workshop manual and do a tuneup per specs.
2/Read the board and take notice.

Paul · Posted: Mon May 17, 2004 7:46 am Post subject:

If you're getting 22 mpg with regular gas, with some city and highway driving you're not doing too bad.

juno · Posted: Thu Jun 17, 2004 1:09 am Post subject:

CMXXXI · Joined: 05 Nov 2002 Posts: 1939 Location: Vicksburg, MS

If you are using Imperial gallons your values are going to differ than what us Board members are achieving here across the pond. Certainly 20-25 is in the "norm" per US gallon, but as they say "your mileage may vary".

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'79 Eurospec 931

924RACR · Posted: Thu Jun 17, 2004 4:21 am Post subject:

I'm averaging about 22mpg US with mixed driving, wish I was doing better... once got 25mpg on a highway trip... still think my car could run better...
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

-nick · Joined: 16 Nov 2002 Posts: 2699 Location: Cambridge, MA

I was getting 22 city / 26.5 hwy over the last 4k miles. However, I'm getting a little bit of "salt & pepper" specs on the plugs which tells me I'm seeing some detonation. Could be from the 91 octane fuel in CO/KS, I might also be running a little too much advance.

So anyway, my numbers are probably at the top end of the mpg scale. With the detonation tuned away I'd probably see slightly worse mileage. Still pretty impressive though!

-nick

juno · Posted: Thu Jun 17, 2004 6:55 pm Post subject:

The most I've had out of a full tank before the light comes on is just under 260 miles. That's when I don't hammer it everywhere. The first few tanks lasted about 235 miles, but that's probably because I was still fascinated by the accelleration.

I managed to get 45 litres (about 10 imperial gallons) in the tank just after the empty light came on. The light came on after 259 miles but I was taking it easy.
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1980 924 Turbo RHD. 3" > 2.5" Stainless straight-through exhaust.

924guy · Posted: Thu Jun 17, 2004 10:14 pm Post subject:

tires / air pressure can make a surprisingly big difference in mpgs... my averages dropped considerably in my truck recently..had two tires that were a bit low..a bit of air and whammo.. right back up goes the mpgs...
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Eric
78 924
82 931 SE "smokey"
99' VehiCross
Y2K Honda Insight
http://www.cardomain.com/id/924Guy
Performance by Pasha

J1NX3D · Joined: 06 Feb 2003 Posts: 1333 Location: New Zealand

i have an old '81 issue of the UK 'Car' mag. They road tested a 924CGT hard, doing 3 high speed runs to try and hit 150mph, and driving over 100mph as well as some corner thrashing. they were stunned to get 25mpg. the author said he wouldnt have believed it if another journalist friend of his didnt get about the same figures the week before in Germany!
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'86 944

Gregarious · Joined: 13 Sep 2003 Posts: 86 Location: Los Angeles

Just going back and reading some of the old postings, I ran across these posted about a year ago. Two things; the better your car 'breathes', the better your milage, and the less friction stopping the free rotation of the engine, the better the milage and power. First, get a foam air filter like K and N, then flush your engine, and put in fully synthetic oil. The US car makers refused to accept the 0 40W oil, but it is accepted by Porsche and Europe in general. Ever since the synthetic came out, it could run just fine but the powers that be were wary of 'light' oils, so the syns artificially made them thicker just to pass them. I just use the European 0 40, and a HIGH PERFORMANCE FILTER. I replace the filter at recommended intervals, but the syn never breaks down. It just gets dirty. So I replace the filter, and top off with new oil. May pick up a little crud, but is still much better than new dino oil.
Once you replace with syn, you should check the idle, and it may have to be reset, lower. Less friction, faster idle. Cooler, more power, better milage, longer life, less wear. Amsoil also makes a synthetic grease, and Watter Wetter is a syn engine coolant that works wonders on the legendary 'hot' running 931s. I rarely get up to normal operating temp now, and you do not need to warm it up before running. Just start and go. Actually, that is the oil. I am in Los Angeles, and don't need antifreeze, but most places need to mix it with the 'Wetter', getting less temp improvement. Unmixed, it gets about 30 degrees cooler. Also, I put in syn brake fluid. Never breaks down, as opposed to standard brake fluid which should be changed too often.

CMXXXI · Joined: 05 Nov 2002 Posts: 1939 Location: Vicksburg, MS

Gregarious · Joined: 13 Sep 2003 Posts: 86 Location: Los Angeles

Sorry I did not make that clear. The system was flushed before replacing with syn. Just brake, not engine. However, I did 'flush' the engine with a quart of syn added a few weeks before going to one hundred percent. I do not believe the engine oils are incompatible anyways.
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A man is known by the friends he makes, and the enemies he keeps...

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Those who cannot do...teach!

Glen931 · Joined: 11 Mar 2005 Posts: 52 Location: Grants Pass, Oregon

you guys dont seem to be getting such good milage. I took my car on highway trip for work and logged 30mpg(driving conservativly). my usual is around 26mpg with mixed driving and i am in no way driving it easy.
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"Nitrous is like a hot chick with an STD, you know you want to hit it, but you are afraid of the consequences"

1980 porsche 931 beige
1987 Porsche 951 red, 51kmiles.. prefect cond.
1978 ford fairmont wagon 2.3 turbo engine

AGD931 · Joined: 17 Mar 2003 Posts: 289 Location: Athens, Greece

I think running without anti-freeze is not a good idea, as it is also a corrosion inhibitor, necessary especially with an engine like the 924's which have an iron block. In addition, the engine runs cooler, thereby improving efficiency.

I live in Athens, Greece and I also do not "need" anti-freeze, but I would not dream of running the car without it.

Arthur
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1981 931 S2
1990 E30 320i Cabrio
1979 Ford Capri Ghia