328 - What is your RPM in 5th gear at 70mph?

Around 3500 RPM for me if I remember correctly. It's been a bit.

 

Isn't 70 a second gear speed???

 

Not a 328 but this is from my 84 308 QV

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Slightly less than post above for a Euro version.

 

That's about what Ferrari says it should be in the OMs. In Section 1, there is a sub-section called "Performances" where they give this kind of information. You do need to use the OM for your specific version as some of the gear ratios vary slightly, but, for both US 328 and US 308QV, 70 mph = ~3500 RPM in 5th gear.
If you'd like to check the accuracy of your dash tachometer, by measuring the flywheel TDC sensor signal using a multi-meter with a Hz function (and knowing the number of flywheel teeth which is something like 144 or 146 IIRC) you can do the math. I use the TDC flywheel signal sensor for adjusting the idle RPM rather than the dash tachometer.

 

‘82 308GTSi 3500rpm 70mph

 

USA cars have a lower final gear ratio than EU ones: means more RPM at the same speed. This is my 308 GTB drysump: 3500 RPM = 125 kmh (78 mph).

Euro cars have 17/63 gears

ciao

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The tachs will do that. Pretty common actually. Needs repair.

 

Brian, how is it possible that there is such a big difference between an Euro and USA 308? If the USA QV is in 5th gear and does only 70 mph at 4000 RPM, it will hit the Rev Limiter at 136 Mph (7700 RPM): too low. Isn't that USA QV in 4th gear?

Thank you very much

ciao​

 

Ferrari instrumentation is so wildly inaccurate and inconsistent I pay it little attention.

According to factory documents for the base version and the US version QV final drive ratio in 5th for the US is 3.736:1 and Base version is 3.514:1. Not a huge difference. Probably closer than any 2 randomly selected tachometer and speedometer pair. Listed top speed in 5th is 134mph @ 6800 for US and 148mph @ 7000 in the base version.

These numbers came from an early base version QV book because that is the only one I have and an 84 US book. I have no idea what changes may have taken place over the production life of the QV.

 

Same info for 88 328's

Base version ratio 3.190:1 and 36.45 kph per 1000 rpm and 255 kph top speed at unknown rpm. 3148 rpm @ 70 if my math was right?

US version 3.6111:1 and 31.9 kpm or 19.8 mph per 1000 rpm and 156 mph or 250 kph top speed at unknown rpm. 3535 rpm @ 70


You can do the math or just drive down the road at 3500 RPM and look at the speed on your GPS.

 

Thank you very much, Brian. I'm not allowed to test the GTB turbo (that has the same gears as Euro 328) with the GPS due to quarantine, sorry!

But I already know that Italian 308 and 328 are more or less a bit above 35 km/h per 1000 rpm (that's matches 36.45 kph per 1000 rpm you wrote for the Italian 328): I checked many times with both. At 110 km/h you are at 3000 rpm, measured several times with new tires and inflated at the correct pressure.

There is an impressive gear ratio difference (and top speed too) between USA and Italian models!

ciao

 

yes, my Euro car just over 3000 rpm at 112kph and at 120kph just under 3500 rpm,

regards
Johnny

 

For some reason I'm remembering it was 4000 RPM at 70 mph on my '77GTB. It was either 70 or 80 mph I can't remember. But I do remember that when we were cruising at 4000 RPM on the highway in the afternoon, it would put my wife to sleep. It was uncanny, I could just knock her out in about a minute and a half.

 

3200 should be about 63 MPH.

 

Somewhere on this forum is an Excel spreadsheet showing gear ratios & top speeds and I believe RPMs.

 

Tire rolling diameters play a big roll. Different makes and even different styles within a make of tires have different measured diameters no matter the size indicated.