C5XTASY

First question: I realize that an unlocked converter dynos lower in power than a locked converter. Does anyone know what the percentage difference is? For example, I have a Yank SS3200 stall with 3.15 gears. If I were to dyno 370 rwhp, unlocked, what should the locked power be?
Second part of the question: Does an unlocked torque converter dyno higher, or lower, than a locked converter as far as torque readings go? And, if so, what is the percentage difference here?
Thanks for any input, knowledge and/or experience in this area.
Ed

Jpr5690

iTrader: (13)

lower for both numbers and their is no real set number.. some really tight converters will loose next to no power unlocked while others will loose 25 hp unlocked

being really generic i would say on avg your 3500-4000 sized converter (built by a reputable company) would loose 15-20 hp on a car that dynos in the mid 400's rwhp

for example my car did 430rwhp unlocked with a 3.73 gear and tci 3500 stall.. i would assume this puts my car right about 450 rwhp locked up .. furthermore i would go on to say that figuring a drivetrain loss of 10%-15% locked up my car has about 510-530 crank hp

but these are just my guesses based on tidbits of info i have found....

12secSS

iTrader: (30)

So far from what I have actually tested, the loss of unlocked vs lock depends on the size of the converter, the stator design used and effficiency of the converter design. I have tested some stock converters that only lost 10 rwhp, others have lost about 15 or so. Most aftermarket converters I have tested lose about 20-50 from locked vs unlocked. There is no percentage loss like drivetrain loss. The horsepower numbers will be lower with an aftermarket stall due to the fact the the rpms are now higher, yet the dyno is reading the same torque. The torque graph will be depreciating from the flash point of the converter (not to be confused with the rated stall speed, this is lower). Torque can sometimes be higher then stock, while some other converters result in lower numbers.

C5XTASY

Thanks for the replies. I think what I will do is contact Yank and see what they say. Theoretically. If anyone knows what occurs through a particular model stall of theirs, they will. They've been awfully helpful in the past.
Ed

C5XTASY

Well, I talked to Dave at Yank today and he told me that on an exceptionally tight converter they saw about a 10-15 difference, horsepower and torque, between locked and unlocked. The usual, he said, on a tight converter, is 20-30, on both horsepower and torque between locked and unlocked (the locked being higher of course). For anyone who was wondering.
Ed