Locking converter at wot
Do yourself a favor and check out back to back pulls.
You may not want to lock it twice.
On my converter when it locks, even over 5000RPM I
-lose- acceleration over unlocked. This is accelerometer
data, the real deal. There's still torque multiplication
going on up there (3500/2.0). Maybe your higher STR
pulls that in, but I wouldn't bet on it being all done at
5000 or even 5500RPM.
I also am not as confident as some, that those clutches
are really made for WOT lockup. Mine has survived a bit
of testing, testing tells me don't bother, so I let it have
an easy life and hope it's a long one. If Yank says not
to, you probably ought to listen.
You may not want to lock it twice.
On my converter when it locks, even over 5000RPM I
-lose- acceleration over unlocked. This is accelerometer
data, the real deal. There's still torque multiplication
going on up there (3500/2.0). Maybe your higher STR
pulls that in, but I wouldn't bet on it being all done at
5000 or even 5500RPM.
I also am not as confident as some, that those clutches
are really made for WOT lockup. Mine has survived a bit
of testing, testing tells me don't bother, so I let it have
an easy life and hope it's a long one. If Yank says not
to, you probably ought to listen.
I can vouch for that , I lock my 4L80 FMV,Circle-D 4800 stall on the button in the beginning of second gear and shift thew it and went from 101mph to 108 mph and dropped almost a full second and that with a duel stage fogger 300 shot and shifting at 7400 rpm's. The converter is bad ***. In my opinion the Circle-D Multi Disk is the baddest converter on the planet
I have a Circle D and It is killer. I lock it up at 4000 rpm in 3rd with a 5500lb truck with a 150 shot and gained mph and you can feel it in the seat of pants when it locks. 
Bringing this back up as I'm also tinkering with locking or not my new FTI converter at WOT in 3rd gear.
The stock tune called for it locking up at 120mph in both 3rd and 4th...so it must be ok if the OEM converter is made to lockup under WOT.
Does it matter more between brands or more between the type of setup you have to really benefit from locking it? Mine is a 3600 with a stock cam/heads bolt on car...so not sure if my converter can take it and not sure if it would be beneficial for me to do so.
The stock tune called for it locking up at 120mph in both 3rd and 4th...so it must be ok if the OEM converter is made to lockup under WOT.
Does it matter more between brands or more between the type of setup you have to really benefit from locking it? Mine is a 3600 with a stock cam/heads bolt on car...so not sure if my converter can take it and not sure if it would be beneficial for me to do so.
Staging Lane
Joined: Jul 2005
Posts: 56
Likes: 0
From: usa
If the correct converter is installed for the setup there is no need to lock it.
Look at the top drag cars running converters and they are not of lock up design NHRA stockers are a good example of this.
If you are lossing 5-6 MPH you have the incorrect converter!
I have drag raced around 40 years and started testing lock ups in the mid 80's and to this day have not found any correctly set up N/A cars that have lowered ET by lock up.
The small MPH if any is not worth the effort and possible failures.
Look at the top drag cars running converters and they are not of lock up design NHRA stockers are a good example of this.
If you are lossing 5-6 MPH you have the incorrect converter!
I have drag raced around 40 years and started testing lock ups in the mid 80's and to this day have not found any correctly set up N/A cars that have lowered ET by lock up.
The small MPH if any is not worth the effort and possible failures.
One more thing you stated if you lose 5-6 mph in the quarter with your converter unlocked vs locked you have the wrong converter. This isn't always the case. If you put an automatic in a big turbo low displacement motor you have to have a very very loose torque converter or else this vacuum powered 3 liter 8.5:1 motor will never push through the converter and build boost.
I have ran a 5 disk lock up converter for a few years and i lock it 90% of the time i do a wide open throttle pull. No breakage no slippage. Car traps 141mph. Torque is in the 630.
On low boost on the dyno i lost 65rwhp or so. High boost i believe it was 110rwhp.
