I do not claim to actually know anything about camshafts. I will point you to
http://www.teamswift.net/3tech/ They sell several different camshafts for the 3 cylinder Geo Metro including an economy camshaft that is very similar to an XFi camshaft. So close in fact that when I inquired about their economy camshaft they advised me not to purchase it since I already had an XFi camshaft. There are links to reviews of many of their products. I have never actually purchased anything from them but they seem to be highly regarded.
Using the tire circumference calculator at
http://www.5speedtransmission.com/calculators.html it appears to me that switching from the standard 145/80 R12 tires that are specified for my 1994 Geo Metro to 155/80 R13 tires would produce almost exactly the same result as swapping the standard 4.105 final drive transmission for an XFI 3.789 final drive transmission.
Cross multiply and divide.
66.3 71.6 Tire circumference
3.789 4.105 Final drive ratio
(4.105 * 66.3) / 71.6 = 3.801
You would have to drive well over 300 miles for the difference to add up to one mile. Since both 4.105 transmissions and 155/80 R13 tires are easier to find I am using the 4.105 transmission and the larger wheels/tires. There are implications to the brake system as well, the larger wheels will make the brakes less effective. I have read a few posts talking about rotational weight and how important it is to keep that to a minimum. What is that all about and how much effect will what I am doing have in that respect?
Linear Mode
