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Registered
Join Date: Aug 2001
Location: Mason, OH
Posts: 2,568
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Cruising gear ?
Don't know why but I starting thinking about this today while I was out cruising around ...
what gear do you typically use when you are cruising at 55/60 when you are out for a drive? I tend to leave it in 4th b/c it keeps the revs up around 4000 but am wondering if the tranny perfers 5th b/c it drops the revs down around 3000. BTW, I am not referring to 55/60 on a highway for extended periods b/c in those cases I am definately am using 5th. Opinions ?????
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Doug '81 SC Coupe |
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06-09-2002, 04:57 AM
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911 user
Join Date: Sep 2001
Location: East of Eden, West of the Sun
Posts: 2,411
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Depends on the road, straight and flat: 5th. If just cruising one doesn't need acceleration or torque, just change down when you do.
If it's a more demanding road or more "intense" driving, a lower gear might be more appropriate. The car itself "tells" you what gear. With 911s when I have a doubt about which is the "right" gear I tend to err on the sound of caution and select the lower.
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Where once the giants walked now Mickey Mouse is king. My other car is also a Porsche. |
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06-09-2002, 05:58 AM
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Crotchety Old Bastard
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You might want to check those numbers. Stock SC 915 gearing is not 4000rpm @ 60mph in 4th gear. More like 3000rpm. That is where I like to keep mine running.
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RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds '78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8 |
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06-09-2002, 05:50 PM
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Registered
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Location: Mason, OH
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Thanks - I'll check the numbers next time I have her out.
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Doug '81 SC Coupe |
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06-09-2002, 05:53 PM
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Rarly's right - I have a spreadsheet of 915 gearing and it tells me about 3150 in 4th for 60mph (with 205/55R16 tyres or equivalent diameter). 5th gear will be 2550.
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1975 911S (in bits) 1969 911T (goes, but need fettling) 1973 BMW 2002tii (in bits, now with turbo) |
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06-09-2002, 06:04 PM
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Registered
Join Date: Jun 2000
Location: bottom left corner of the world
Posts: 22,795
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If I'm not going to be speeding up of slowing down I guess I just use top. But my favorite cruising is in top gear at about 3,500 to 4,000rpm (or more). Just enough to make the car feel lively.
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06-09-2002, 07:17 PM
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Senior Member
Join Date: Feb 2000
Location: Lacey, WA. USA
Posts: 25,308
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No way I'd use 5th for speeds under 60. Actually,at fifty I'm dropping to 3rd. I'd agree with Bill. Perfect is about 3800 or more in 5th gear. That's what the car likes. Problem is, that's about 90 mph.
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Man of Carbon Fiber (stronger than steel) Mocha 1978 911SC. "Coco" |
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06-09-2002, 09:20 PM
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Administrator
Join Date: Feb 2000
Location: Los Angeles
Posts: 13,334
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For me, 4000 rpm in 5th is only 79 mph.
 Fourth is out of the question. With solid motor mounts, this means very non-relaxing highway cruising. However, the torque is always on tap. 
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Jack Olsen 1972 911 My new video about my garage. • A video from German TV about my 911 |
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06-09-2002, 09:48 PM
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78 Porsche 911SC 3.0L, 3.3Turbo soon. 
1975, 1969 Porsche 911S, 911T 2.7S CIS, 2.0T ca
