How fast does a 308 really go at redline in 5th?

That's amazing that the top speed doubled in five years. Had mine wide open in fifth for a mile or so and It would only go 85 in my 1980.

Forza Ferrari!

 

My 2v has reached 142mph (by GPS). QV should, at least theoretically, be a few miles an hour faster, and carb car a few miles/hour faster than that.

This is assuming that all other variables are constant, which is a big if. Tuning, wind, load, incline, and a million other little things can make some significant difference.

 

Some years back I hit 280km/h on the speedo at 7800rpm in my -85 GTB QV Euro (autobahn in Germany). Dont know what that translates in to real speed but I recently checked my speed with a GPS, the speedo seem to be about 10% too optimistic (only checked the 50-140km/h range though).

 

Dug up the gear calc I wrote a number of yrs ago. Top speed for each gear for each model and where I had the data on the gears for each variant. THis is theoritical top speed at 7800rpm.

GT4:
1st:45mph
2nd:65mph
3rd:91mph
4th:110mph
5th:189mph

308:
1st:45mph
2nd:65mph
3rd:91mph
4th:110mph
5th:176-Base
5th:166-USA
5th:175-CH

328:
1st:45mph
2nd:65mph
3rd:91mph
4th:124mph
5th:182-Base
5th:166-USA
5th:188-CH

Mondial:
1st:42mph
2nd:64mph
3rd:89mph
4th:120mph
5th:163-Base
5th:173-USA

 

"Anyone out there have experience redlining a 308 in 5th gear and reading the speedo ? "

Ha! Italian speedometers fall into the same category as handbrakes and AC systems: Broken BEFORE they left the factory. Add 25+ years of wear. Also, keep in mind that cars provided for testing by magazines were, from many manufacturors "warmed over" and not representative of the cars in their showrooms. Occasionally the mags were smart enough to "borrow" a privately owned car for their testing.

 

I would not try to rev up my 2V more than 6000/6500 rpm (sodium valves) -
and a speed of 125 mph (=200 km/h) is definitately enough for my car ... and me

doubt, if it would really go faster... and it does not have to
cruising speed is 95/100mph max... even on german autobahns

I`m happy

.

 

This does not really match my experiences.

I was doing 165 mph indicated in 5th when the tacho read 7800, which in true miles was probably closer to 150 mph. the gap between 110 and 189 between 4th and 5th is rather large, I'd say. Typo?

 

I like this table, and imagine that it's reasonably accurate (ignoring a lot of variables for individual cars which I mentioned above), except for 189 in a GT4.

That seems astonishingly fast for almost any car of that era. Even "Supercars" were not, for the most part, that fast in the early 70's.

 

This theoretical is without air resistance or rolling friction. basically that's the top speed the wheels will reach for that gear, if you could overcome all resistance to get there.

Good point on the gap, went back to the sheet. a miss calc on the GT4: 4th 124mph; 5th 162mph.

All the velocity numbers were generated from the gear calcs in spreedsheet I put together some time ago. put in an rpm and it'll spit out the mph.

I also started on using it to calculate tq for a given gear based on input from the crank, didn't finish as it was getting fairly complex and it would only be relevant to what ever engine was dyno tested, I don't have stock motor numbers off an engine only dyno.

Next time I have a gear box apart I'll double check the gear tooth count to the posted numbers from the WSM.

 

Thanks for providing this information! I wouldn't know where to start to make those calculations.

 

OK, seems that there was some typos in the WSM, counted gears and double checked the numbers:

Base 2v /4v usa Gear
RPM 1 2 3 4 5
3000 15.82 22.37 31.95 43.47 58.83
5000 26.37 37.28 53.25 72.46 98.06
6000 31.65 44.74 63.91 86.95 114.73
7000 36.92 52.20 74.56 101.44 133.85
7800 41.14 58.16 83.08 113.03 149.14

2v USA Gear
RPM 1 2 3 4 5
3000 16.52 24.52 35.03 47.66 62.27
5000 27.53 40.87 58.38 79.43 103.79
6000 33.04 49.05 70.05 95.31 121.43
7000 38.55 57.22 81.73 111.20 141.67
7800 42.95 63.76 91.07 123.91 157.86

this is the double check using the gear ratio to rpm from crank-->drop gears-->gear-->final-->tire.
rpm idle gear final MPM MPH
7,800.00 7,020.00 8,190.00 2,210.00 2.63 157.79 5th
7,800.00 7,020.00 6,267.86 1,691.33 2.01 120.76 4th
7,800.00 7,020.00 4,606.88 1,243.13 1.48 88.76 3rd
7,800.00 7,020.00 3,225.41 870.35 1.04 62.14 2nd
7,800.00 7,020.00 2,172.86 586.33 0.70 41.86 1st

seems that the drop gear ratios cause a bit of confusion for the WSM gear ratio calcs. a number of typos..