TBS 871 to BDS 1471 questions?
#13
Your top pulley is small but so is your bottom pulley, looks like you are not overdriven. You can overdrive 15% easily with no ill effects since you have a cooler. I also would be concerned with the bottom opening if it is the small delta (mixture distribution using carbs), not just the delta at one end. I switched to a 14 from an 8, not much difference really and I still own the 8. I just needed a bit more air movement with the new lower compression, larger CID and improved heads engine. You want to use the smallest blower that will allow you to make your target boost at 5 to 15% overdrive.
#14
Your top pulley is small but so is your bottom pulley, looks like you are not overdriven. You can overdrive 15% easily with no ill effects since you have a cooler. I also would be concerned with the bottom opening if it is the small delta (mixture distribution using carbs), not just the delta at one end. I switched to a 14 from an 8, not much difference really and I still own the 8. I just needed a bit more air movement with the new lower compression, larger CID and improved heads engine. You want to use the smallest blower that will allow you to make your target boost at 5 to 15% overdrive.
#16
Geronimo36
Gold Member
The size of the top pully being small doesn't necessarily mean anything. You need to know the size of the top and bottom pulleys together to see what your drive ratio is.
#17
Geronimo36
Gold Member
Here's a full chart of 8MM, 1/2", 12.9MM and 14MM pulleys. I run 9.4% OD on my 8:71's and have found that to be fine.
http://goodvibesracing.com/Ratio_Charts.htm
http://goodvibesracing.com/Ratio_Charts.htm