Howard Coleman

iTrader: (6)

i am upsizing my twin garrett to4 setup compressors and am deciding between 2 wheels that have the same 41 lb/min flow, the same excellent efficiencies but differ as one of the wheels has a better surgeline.

here are the numbers locating each turbo surgeline:

bar to4 s3 to4 46 to4 46 Super
surgeline location
pounds per minute
1.4 7.5 8.9 7.5
1.6 10 11 9
1.8 13.5 13.2 10.75
2 16.5 16.5 13.25
2.2 19.1 19 16.2
2.4 22 22.8 18

my current turbos (to4 s3) were purposely selected for early boost ( 1.9 X 2.75 comp wheels) and are not efficient above 30 lbs/min. the to4 46 is really good from 30-41 pounds and if you note the comparative surgeline above it looks like both of the larger wheels have as good or better surgeline location, especially the Super.

does the Super to4's surgeline location being further to the left indicate earlier spool than the standard to4?

the to4 46 wheel is 2.003 X 2.95 and the to4 46 Super is 2.003 X 3.2 (making it a 39 trim so i am wondering why the Majestic Turbo site refers to it as a Super 46)

kevin draper at Majestic advised me to go w the standard 46, that the surgeline location is not a big deal. there is a significant advantage based on the above numbers for the Super. based on my dealings w vendors ( both turbo and engine vendors) over the last few years i have gained a great deal of skepticism. there's alot of brainpower here and i would be delighted for any help.

based on my 2200 logged miles on the current to4 s3 wheels i expect to have no problem swinging the larger compressors.

howard coleman

fdracer

the 46 and super 46 will make about the same power per psi, but the 46 will spool a little faster due to the smaller exducer. the larger exducer on the super will allow you to boost more before you surge but will sacrifice spool in order to do so. the differences between the two will probably be minimal though. what's the compressor a/r for each one?