First off I am not meaning this for a slam to PTC, Dusty, Lane or any body else at PTC, my only input to this is my first hand experience and goal being to put my info out there for future choices of those looking at sprag vs not with non LU.
2 years back I built a mild build (see signature) combo is about 550ish maybe a little more and the stall speed chosen was around 3400. And Dusty as usual was outstanding in working with me to get a convertor setup for my combo and the stall speed was perfect. But...unfortunately with a spragless my trans got to hot and eventually died.
My trans cooler was/is a Stacked plate Long H7B 11" x 11" x 1.5 rated at 29000 BTU placed right in the grill airflow and gets air pulled across it at low speeds via electric fan and I was running Dex IV fluid when it died.
Heres the cooler (not endorsing the company in the thread just an example)
http://www.ebay.com/itm/Long-DANA-H...Parts_Accessories&hash=item338e2a1ab7&vxp=mtr
I first noticed it when driving through the mountains going to BG/GS nats and the trans burped out the dipstick tube and vent with the cruise on 65-70 and hitting the long grades through the mountain passes. Also my driving style is I drive my car alot and put it through the paces. This meaning strip, roll racing (45 -120 ish) back to back, long grades and may have to nail it to pass while on that grade.
While out one night a group of us gt into a few back to back rolling runs and on the 3 run back to back the 2-3 flared bad and smoke rolled out of my car (from the trans burping fluid out from overheating on teh exhaust) and was slipping and done with the fluid black as tar and just plain cooked.
I keep a 200 as a spare and decided to do some testing so I pulled my old trans, replaced the cooler , flushed the lines and filled and drained the conv several times and slapped it in the car.
Running at 55-60 sustained on flat ground, in OD, 98 degree summer day, no boost, for 5-7 miles my sump on my trans was 212-219 degrees. If I stood in it from low speed roll after the trans is already heat soaked at the temp I mentioned and ran to about half way through 3rd my temps creeped to 238. And the temp stayed elevated while driving unless I parked the car and let it cool or let it idle in park.
Having seen enough from my tests I pulled the transmission/conv and started doing some research. I called 7 different big name trans places (ATI, Pro torque, CPT, Art Carr, B&M to name a few) not telling them it was a PTC and I also looked on line at several chat rooms and blogs not one said that a spragless is for the street due to the excessive heat built. Pro torque went so far as to say they wont even sell a spragless conv to someone that drives on the street.
After this I was pretty frustrated being that I now had to get my trans rebuilt and get the conv fixed.
Spoke with Dusty and Lane and we came to the conclusion that a sprag should be added to try and get the temps down and they completely worked with me with great customer service like they are known for.
So long story short.....same scenario with the only change being sprag added and Trick shift trans fluid my temps in the same situation are 25 degrees cooler and the temp recovers after a hit/pass/run. Sprag fixed my issue.
Dusty called me since with a follow up to see if everything was working out and to see if temps dropped, which furthers the example of great customer service they are known for. No mud slingin meant towards anyone, just that my experience and driving style the spragless didn't work, this I had to find out the hard way and due to that I want others to know so maybe they can make a better informed decision on such a not cheap part.