2500 rpm and 70 mph

[frosty2]

Hi all I have a 911T with a 2.4L coupled with a 901 not sure what gears are in it but at
70 mph I am doing somewhere around 4000 rpm.
I was reading someone's restoration post the other day which for the life of me I can't seem to find again but he started out with a very rusty silver long hood and they done an amazing job of restoring it and painted it orange.
They added a 2.4 with a 901 and I believe he was in the east coast and he made the comment that it ran 70mph at 2500 rpm.
Just wondering what rpm is normal with this set up at 70mph.

Thanks
Mike

[Hnichols]

I'm not all that knowledgeable about older 911s with the 901 tranny, but 2500 rpm at 70 can't be right (it wasn't 70 kph was it?). 4K -- at least. At 70 mph you want to hear that engine ...

[procan]

I have a 902/16 tranny coupled to a 2.0, and at 70 mph I'm in that 4,000 rpm range as well. If you check the model number of your tranny, you can look up the stock gear ratios.

[tshebib]

Here you go

1968 912 junker reincarnation

The RPM reference is in post #300

[Bill Verburg]

Originally Posted by frosty2

Hi all I have a 911T with a 2.4L coupled with a 901 not sure what gears are in it but at
70 mph I am doing somewhere around 4000 rpm.
I was reading someone's restoration post the other day which for the life of me I can't seem to find again but he started out with a very rusty silver long hood and they done an amazing job of restoring it and painted it orange.
They added a 2.4 with a 901 and I believe he was in the east coast and he made the comment that it ran 70mph at 2500 rpm.
Just wondering what rpm is normal with this set up at 70mph.

Thanks
Mike

More info is needed, you garage shows a '73T, which would have a 915/02 if its a 5 speed

2.4 is correct engine size for that year and model too.

if so 4k rpm should give ~85mph +/- depending on the rear tires

4k in 4th should give ~67

[AshEvan]

Ihaa stock 74 911 and at 4K RPM I am at about 80 MPH

[frosty2]

Thanks for the quick responses guys.Thanks tshebib that's the post i was trying to find it so I could listen to his ciip again I love the sound of his car.
Yes Bill my car is a 1973 911T with a 2.4 and zenith carbs as its a euro car but the Po
Changed the 915 to a 911/01 model#7108388

[frosty2]

Sorry Bill almost forgot I'm running Falken 225/50/R16's on the back with 205/55/R16's
On the front.

Thanks again
Mike

[AE354803]

If you look at the gear charts

Pelican Technical Article: 901 & 915 Transmission Gear Ratios

and compare that to transmission setups

901 5-SPEED TRANSAXLE SPECIFICATIONS-GBOX Transmission

I think you would have to get up into the ZA/ZD gears before you would see those speeds at those RPM, but it looks like the gears should exist somewhere?

Even then you would be at 3500 RPM/ 75 MPH without messing with final drive/tire diameter etc.

This is a good resource also (http://members.rennlist.com/chuxter/901&915ratios.htm )

[frosty2]

Thanks AE354803 by those charts it looks like my 5th gear is an AZ gear

Thanks
Mike

[Bakester]

Not to hijack but are the ROW 915 different from US ratios? Thought I saw where someone claimed they were lower but can't seem to find euro specific numbers. Thanks.

[gamin]

My 70T with original 911 5 sp tranny is nowhere near 4000 at 70 mph. I'll have to check but I think it is much closer to 3000 maybe 3200. According to the gps my speedo is pretty close to spot on. Check yours with a gps.

[frosty2]

Thanks Gary unfortunately its winter here and my car is put away but i'm sure
I am doing approx 60 mph at 3200 with my gps but I will have to Waite till spring
to double check it now.

Thanks
Mike

[Bill Verburg]

a 911/01 has ZA stock, so w/ 225/50 x16 tires 4k is ~85mph, 3k is ~64mph

[Bill Verburg]

Originally Posted by Bakester

Not to hijack but are the ROW 915 different from US ratios? Thought I saw where someone claimed they were lower but can't seem to find euro specific numbers. Thanks.

not in '72 or 73, all 5speeds used the same gear set for those years
except for the Carrera and special orders, there were also 4 speed and 5 speeds

[frosty2]

Thanks Bill the 3000 @ 64mph looks about right so maybe I'm all wet on my
4000 rpm. Maybe I was doing 80 ish rather than 70 ish it's on jack stands right now as i'm doing an oil change and some winter stuff but as soon as I get some nice weather I am going to check and will post.

Thanks
Mike

[Kemo]

A buddy of mine installed a 5th gear in his 914 which was mated to a 3.2. This was supposed to get him at about 2500 rpms at 70mph. I helped him with the install an if i remember correctly, you had to some to flip the gears around somehow. It seemed the angle of the teeth was somhow backwards. Ill ask him to chime in with some links. I think i was documented on one of the 914 boards

[gamin]

Just checked. 911/01 - 60 mph = 2800 rpm, 70 mph = 3250 rpm. + or - a few of course.
7:31 ring and pinion, 29:22 ZA 5th gear, 205/60-15 tires.

[T77911S]

my 930 does 70 at 2500. thats with 18 in rims which BTW now makes the speedo accurate, i have the ticket to prove it. i have checked it with the GPS.

my 77s was way above 2500 at 70 even with 16 inch wheels. so for him to be at 70 at 2500, i dont htink so. i am not even sure porsche made anything that you could put together for that car that he could do that.

i dont think i would even want that car to be at 2500 at 70 unless i did i LOT