Alfa Romeo Forums banner

Is there an overdrive gear on 164Q??

2K views 24 replies 11 participants last post by  MrT 
#1 ·
Can someone having Q post their engine rpms at corresponding speeds?? I wanna compare with mine, I know its higher geared than L tranny, but would like to see some comparison numbers.... speed vs rpms

thanks,
-Pavan.
 
#2 ·
164Q axle ratio 17/58 3.412 so .916 overdrive in 5th overall ratio in 5th 3.125 23.03 mph @ 1000 RPM. So in 4th 18.24 mph @ 1000 rpm
164LS axle ratio 17/57 3.353 still .916 OD in 5th but overall ratio in 5th 3.071 so 23.43 mph in 5th. So in 4th 18.56 mph @ 1000 rpm.

164S 3.412 17/58 overall ratio in 5th 3.125 and same 23.03 mph in 5th @ 1000 rpm

164B/L 3.111 18/56 overall ratio in 5th 2.849 so 25.62 mph in 5th @1000 rpm
 
#4 ·
THanks Steve, tht gives me some idea... so there should be a lot of difference comparing L with Q, tht explains in my case. I would also like for someone to post the rpms at all other speeds like at 30mph, 65mph and one at 90mph. I will post mine later today if I got to drive it, as I am driving my L this week

-Pavan.

-Pavan.
 
#9 · (Edited)
Here is what I got using tht spreadsheet...

R & P Tire Size ( over all dia in.)
3.412 25

3.5 2.176 1.523 1.156 0.916 0.65
RPM 1st 2nd 3rd 4th 5th 6th
1000 6.23 10.02 14.31 18.86 23.80 33.54
1250 7.79 12.52 17.89 23.57 29.75 41.92
1500 9.34 15.03 21.47 28.28 35.70 50.30
1750 10.90 17.53 25.05 33.00 41.64 58.69
2000 12.46 20.03 28.63 37.71 47.59 67.07
2250 14.01 22.54 32.20 42.43 53.54 75.45
2500 15.57 25.04 35.78 47.14 59.49 83.84
2750 17.13 27.55 39.36 51.86 65.44 92.22
3000 18.68 30.05 42.94 56.57 71.39 100.61
3250 20.24 32.56 46.52 61.28 77.34 108.99
3500 21.80 35.06 50.09 66.00 83.29 117.37
3750 23.36 37.57 53.67 70.71 89.24 125.76
4000 24.91 40.07 57.25 75.43 95.19 134.14
4250 26.47 42.57 60.83 80.14 101.14 142.53
4500 28.03 45.08 64.41 84.85 107.09 150.91
4750 29.58 47.58 67.98 89.57 113.04 159.29
5000 31.14 50.09 71.56 94.28 118.99 167.68
5250 32.70 52.59 75.14 99.00 124.93 176.06
5500 34.25 55.10 78.72 103.71 130.88 184.45
5750 35.81 57.60 82.30 108.42 136.83 192.83
6000 37.37 60.10 85.88 113.14 142.78 201.21
6250 38.93 62.61 89.45 117.85 148.73 209.60
6500 40.48 65.11 93.03 122.57 154.68 217.98
6750 42.04 67.62 96.61 127.28 160.63 226.36
7000 43.60 70.12 100.19 132.00 166.58 234.75
7250 45.15 72.63 103.77 136.71 172.53 243.13
7500 46.71 75.13 107.34 141.42 178.48 251.52
7750 48.27 77.64 110.92 146.14 184.43 259.90
8000 49.82 80.14 114.50 150.85 190.38 268.28

just ignore the 6th gear...

-Pavan
 
#10 · (Edited)
Here is what I got using tht spreadsheet...

R & P Tire Size ( over all dia inches)
3.412 15

just ignore the 6th gear... does the rest of the data looks right??

-Pavan
Math maybe correct but tire diameter needs to be for tire diamter of specfic size 15" tire you are using. The stock 195-65-15 tire that came with most USA 164 models has diameter of 25".

You need to know diameter of size tire you are using.
 
#11 ·
There is a location in the spreadsheet to insert tire diameter. The math is correct, as I have been using this spreadsheet for years. The 6th gear section was added to calculate speeds for a 156 6 speeds we are working with.
 
#12 ·
But you have to use tire diameter such as 25" for 195-65-15 tire not 15" right?
 
#14 ·
You need to enter overall tire diameter not tire size. On my spreadsheet it is cell I2.

My reason for wanting a 6 speed is for good acceleration in the lower gears and lower RPM's while cruising. The S has a 3.412 r & p, which means on trips cruising @ 85-95 mph you are turning lots of rpm. The 6 speeds have tighter gear placement and still lower RPM. Another plus of the 156 6 speeds is the availably of quaife lsd units. The 164 really needs more traction, especially in the wet and when aggressively driving the car.
 
#15 ·
Today 60mph = 2600rpm 80mph =3400rpm
215/45-17
I hope that helps! Believe it or not, but I was actually flowing with traffic not overtaking anyone :eek:. Wife will jump on me for speeding while she is in car :p.
 
#16 ·
164Q Speeds and RPM's

My 164Q with 195-65R-15 Michelin WMXr all weather tires turns about 2.5k at 60 MPH and about 3K at 70 MPH. These are not by any means "performance" tires! Wish it had a six speed!
 
#19 ·
The one aspect this speed spreadsheet can not take into account is actual achievable RPM and the wind resistance. At some point the car will not have enough power to overcome the wind resistance. The spreadsheet really works well for look at the effects of tire size and gear ratio changes.
 
#22 · (Edited)
The one aspect this speed spreadsheet can not take into account is actual achievable RPM and the wind resistance. At some point the car will not have enough power to overcome the wind resistance.
Andrew, it is reasonable to consider adding a small amount of computation in the spreadsheet to take a drag coefficient, make a rolling resistance approximation, and calculate a power requirement (still air, level road) to drive the car at a certain speed. R&T and other pubs often enough (I think) give a drag coefficient for such purposes. I believe I've seen one for the 164.

Never mind that they are only of use over a limited range. The sole purpose behind this would be to let an owner see how much pwer would reasonably be required to push the car at a certain speed, so he could compare to published engine specs or to dyno runs and see whether the car reasonably should do the speed. I can see the techno-philes doing that. I could see me doing that.

I vaguely recall (on the digest venue, I believe) a comparison of L and S engines and gearing which said that the cars reached top speed at the same power -- the L at peak power and the under-geared S at declining power beyond the peak power point.

Michael

addendum: this isn't the thread I recalled, but it seemed interesting enough to add:

http://www.digest.net/alfa/FAQ/164/forum2/DCForumID4/1501.html
 
#20 ·
Thank you for posting this chart. I imported it into MS Word and set up a nice chart for reference. I didn't realize that I was going as fast as I thought I was. :eek:

Is there a web source for tire size?
 
#21 ·
The calculation for overall tire diamiter, if that is what your are looking for Doc is tire size say 215/55/16 would be 215 X.55 X 2/25.4 plus wheel size of 16. So 215 x .55 = 118.25 X 2 = 236.50 divided by 25.4 = 9.31 + 16" = 25.31" a standard 195/65/15 would be 24.98" using this calc.
 
#23 ·
Let me get used to this car and keep it on the road until I can get the two Duettos turned into one decent driver. Then I may look at 164 mods. But if I have three Alfas that don't run, I'll have to sleep in the garage!
 
#24 ·
Mr T,
When you start adding drag co-efficients and other variables into the equation, one must question at what point will you stop to get accurate enough numbers. All cars not are exactly the same. Horsepower differs depending on age of the engine, state of tune, elevation, and outside temp to name a few. You can try and standardize some of this by using SAE standard numbers, but that is for comparison purposes - not what is actually happening.

I have seen the L vs S top speed treads over the years. In theory the L should have a higher top speed over the L because of its different gearing. The problem is that gearing also effects where in the power band the motor can run. The earliest example of this is the 82-83 GTV6 with a 3.42 vs a 81,84-86 with a 4.10. In theory the 82-83 should have a faster top speed, but in reality with the 3.42 gearing, when you shift to 5th from the top of 4th, you cannot get the last 700 rpm's out of the motor compared to the 4.10 cars.

Number crunching is great, but in many cases there are many variables that you do not expect until you are actually pushing the car in its environment. You mention several uses of such data, but in reality how many owners have actually had their cars dynoed or even on the track. Most of these type numbers would be used solely in bench racing.
 
#25 ·
You are quite right, Andrew, that there would be little real utility to the calculation. And bench-racers are the primary audience for such a calculation. Someday when I feel adventurous enough, I'll sort through the units (hp, kW, furlongs per fortnight, etc) of the calculation and figure out how to use the info just because it would be fun. I don't even know right now whether the commonly used drag coefficient calculation returns a force or a dissipated power value for any given velocity. It just seemed interesting at the time.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top