ive seen V160 with barly over stock motors break too.
Jake, I really have to question that comment of yours..WOW!!!!
With over six years of modifying my SC400 and on the forums this is what I have found and read to date... I'm very confident this information is correct based on my continued findings.. Hey, but if someone knows other wise please let me know...
Stock SC400/Soarer Automatic transmission (A34OE)- Has been known to handle 400whp with an additional tranny cooler...However, I personally have wasted two trannies with just over 300whp and ton of torque... One popped and gave up the ghost in 2nd gear, and the other built up tranny overheated on me a few years ago with no additional cooler (my bad)... Timely shifts too are suspect with big power and torque as well... My on going delema...
Boostlogic.com - Lexus auto tranny's can be made to handle 700hp from what I have heard but don't quote me on that..... I would "venture to guess" with that much power you will either need a shift kit or triptronic control to manage timely shifts...
R154 - As noted on the CLub lexus forum in many threads the tranny power claims have been reported to be right around 500whp.. That is pushing the envelope from what I have read with the R154's....
V160 - Limitless pretty much...4 digit horsepower... I have seen many handling 1000hp+...
W58 - The weakest of the bunch...Based on what Jake said maybe 400-450whp which I would really like to see... I have heard 400whp is really pushing it on those weak arse W58's...
You can also look into the Th400's and other Ford and Chevy auto trannys swaps but then you are in over your head with custom mods and fits...
So in the end if you own a Soarer/SC400 this is what you are looking at for swap and built options.. Also keep in mind the stock SC400/Soarer driveshafts and spindles have their breaking points too...