Craig T.

This messege sparked my curiosity. I had to find out for myself. I just ran mine up to 137 mph. That’s all she had.

I have two years on a high-quality race shop rebuild, but the motor is in its stock configuration and compression. I have stock gears, 17” Fikse’s, with Kuhmo Victoracers. I thought she was faster than that, but I’m not getting anywhere near 130mph at Willow Springs Raceway.

phil gumm

I think I remember reading if a carrera failed to exceed 147 mph @ redline consult your Porsche dealer I've only seen 140+ - with my "stones"

Edgy01

The 180mph speedos were put in the 930 turbos. In the era of the 911SC the usual fitment for them was the 150. Unfortunately, US DOT rules dictated the 85mph speedo for a few years around 1980.

Jay Laifman

Thanks. Too bad the rest of the car is not attached to the speedo! (It's not in my 73 either, it still has the stock one).

Scott1551

I have a 1969 911 T and it my first. It needs to be re-done does anyboby have any ideas for me? It needs pans, interior and paint. The engine is strong and has no problems. It's a 2.0 6 cylender with a 5 speed trans. I cant figuer out why it has factory finder flairs. Any one have any ideas?

Alan Herod

My SC will probably run as fast top end as anyone's. Admittedly back straight at VIR is slightly uphill; but, I can easily pull a 996 up to about 120 whereupon the SC body runs into an aerodynamic wall and begins to accelerate much more slowly. I can hold 4th to 6900 (3.6), rev limiter on the 3.6 is 7000 (about 140 in fourth). Shifting into fifth which is geared much to high (25mph per 1000) produces little that could be called acceleration (rear tires are 255/40-17 so mph may be a little pessimistic, but not much).

How did Porsche achieve their claimed top speed? The true 145-147 will require an incredibly long straight or a lower fifth gear. There are a few things that can be done to reduce drag -- I have raised RSR spindles and the ride height is set up for that (as low as the JRZ will accomodate). The flag mirrors could be removed as well as the windshield wipers. Surely, Porsche did not address the windshield lip or the drip rails; but, the car would have to be set up perfectly to achieve Porsche's claimed 147 with the perfect final drive and a very long straight.

For what its worth -- with 225/50 15s, car accelerates much better and top speed is probably 160+ indicated.

LaughaC

I 2nd the motion that low profile tires greatly improve acceleration in these cars. With my 40's I managed to bury my 150 speedo in a reasonable amount of time. Of course I doubt I really broke 140, but it made me happy.

RAJU

My `83 SC has a 170 speedo from factory. The manual that came with the car, says top speed is 138mph. And for ''DARISC" , I have passed stronger cars than carrears on track and also been passed by lesser cars than mine. It`s not the size ect.........

DARISC

..

Alan Herod

If 137mph is top speed with 180 HP; then 219 HP is required to go 145, assuming everything else is equal. Power to overcome drag increases as the cube of the speed increase.

butzip

I think the only way to accurately measure your top speed is with a GPS. Mine logs top speed. 141 in 1988 carrera cab. You simply cannot trust the speedo @ that speed and you really shouldn't be looking at it @ that speed either Look at me trying to preach responsibility @ 141mph

Alan Herod

Concur about watching speed, I can't see beyond 120 on the speedo anyway (blocked by steering wheel) - I watch the tach for V-max. I check instruments quite a bit on the straight - check tach same place each time for comparison.

Alan Herod

In an effort to find ways to reduce drag I posted a thread on racing board.

https://rennlist.com/forums/racing-and-drivers-education-forum/394679-winter-drag-loss-project.html

not much traffic yet.

Craig T.

I have a Garmin hand held GPS I use for mountian biking. It measures top speed, distance traveled, etc.. There is a flat 2 mile farm road by my house that is seldom used by anything but pickers. I got a 137 mph on the speedo earlier this week. I'll check it against the GPS tomorrow.

Oh, about responsibility, I'll wear my helmet and nomex shoes...lol.