Gearing problems?

[Guest Anonymous]

If I put a 350 into my 75 Datsun 280z with a turbo 350 or 400 auto. what would my top speed be about? I'm not sure about the gearing in my car I guess its the r180 rearend if thats the only rear that came with the car. I just want a ballpark figure and I will not be going to the r200 for a while.

[blueovalz]

I don't have the URL address here at work with me, but if I remember when I get home, I'll send you the URL for a neat graph that shows what your speed will be at differnt RPMs. Inputs include tire size, tranny, and diff gear ratios (unless someone beats me too it)

[Modern Motorsports Ltd]

depending on your rear end ratio and what rpm's you want to run at.......assuming 1:1 3rd gear as those have,

a 3.54 diff with a 24.7" tall tire puts you at

4000rpm at 83mph

5000rpm at 104mph

6000rpm at 124mph

 

if your diff ratio is otherwise then just alter by the percent difference....ie. 3.9 diff is 10% higher geared so just drop 10% from figures above.......4000 rpm would be (83-8.3)=~75mph, same applies for a different tire height.

 

hope that helps, you can do a rather simple wheel turning excercise to find out your current diff ratio if interested, it's been posted here and is at www.zhome.com as well

 

Here's an Oz site for calculating this

Oz site, result is kph but it converts to mph as well (times 0.6)

and here's anothermph ratio calculator

 

I also have an excel sheet I've used that I can send to anyone, just drop me a line.

 

[ October 10, 2001: Message edited by: Ross C ]

[blueovalz]

Nathan, check this graph out for speed vs gearing vs rpm http://www.geocities.com/z_design_studio/

 

Terry