Does A/R correlate to faster spools?
 

Can someone explain the difference between the A/R of turbos. Im looking at the S366, but do i get the .88 or the .91 A/R? I have read that area is more important for faster spooling compared to radius, but still not quite sure which to get. Read my signature for current mods. Keep in mind that this is a DD. Thanks for the help.

With the same size that time wheel, a smaller AR will spool faster but will choke sooner as well.

So if Im looking to hit boost faster, then I should get the .88?

Yep, just keep in mind it wont pull as hard at the top of gears due to the turbine choking more easily. Its a tradeoff between fast spool and top end power.

I would go with the bigger a/r of the two... the s366 is gonna spool really fast already.

Bigger it is. On 93 octane tune I'm currently sitting at 330.4. Take a look at my number. What do y'all think. Was hoping the graph would be more consistent but there is a stutter at about the 2700 mark then takes off, converter?,. I was told that timing is at a safe level so I can get on it all day and be safe. I'm happy with the numbers and will be going back for turbo work.

Those two turbo's are virtually gonna be the same. The .88 is an open scroll and the .91 is a divide scroll. (I don't think they take into account on the material of the divider when they calculate the a/r) I don't think you could even tell the difference in performance between them. I have a .91 s366 on the 5.3 in my 69 c10 and that thing spools stupid fast and is a blast to drive! lol

Since you are considering BW check out their Matchbot software: Performance Turbos | BorgWarner Turbo Systems

I followed along with this video by the The Tuning School:
If anything, it's fun to nerd out on lol

This should be stickied. God what an education it was.

i agree very useful video