Confused about fluid coupling issue

[Bdsankey]

I don't want to de-rail the thread, but reading it got me interested in the underlying principles of torque converters. I think I understand them but I have a question. A stock duramax makes peak torque at around 1600 rpm I believe, but the stall of the stock converter is at around 2000 rpm. Does this mean that you typical trying to match the stall with the peak horsepower instead of peak torque? What is the typical criteria for trying to select a torque converter?

You select a torque converter that has the stall speed required to get the turbo of your choice spooled properly. Some converters couple extremely well, some don't couple worth a damn. Coupling is how they act in an un-locked situation in terms of minimizing the RPM difference between the crankshaft and the input shaft.

 

[N2BRK]

I've been quiet, waiting for some info when PI got the converter back. They just called - said there was wear and some minor issues that they will repair/update and send it back. But they claim that my problem is not converter related.

They opine a solenoid could be to blame. Is this why the K is exhibiting the same exact problem? I have an R that just arrived, but I'm not keen on replacing any converter until I'm satisfied that this isn't something else.

Am I at the point where I need a shop to measure pressure and diag or is this sounding like a solenoid swap and see kinda thing?

 

[Chevy1925]

I've been quiet, waiting for some info when PI got the converter back. They just called - said there was wear and some minor issues that they will repair/update and send it back. But they claim that my problem is not converter related.

They opine a solenoid could be to blame. Is this why the K is exhibiting the same exact problem? I have an R that just arrived, but I'm not keen on replacing any converter until I'm satisfied that this isn't something else.

Am I at the point where I need a shop to measure pressure and diag or is this sounding like a solenoid swap and see kinda thing?

if you truly feel something isnt right as far as how the converter/s is/are acting, i would definitely start diag'ing the trans before throwing anything else in.

 

[N2BRK]

I was fully on board with it being a mismatch of engine to k factor on the converter, and I gave up saying it has to be a fluid problem, until PI called and said it isn't the converter. I think it was around the time I put in the 12mm exergy that I started having this problem, so I thought it just hurt the vert.

I called a couple friends and they have SOLAS but no mechanical way to test the trans. I seem to remember Mike L saying the scan tools are useless and it ha to be mechanical.

My other "diagnostic" choice is to get some trans fluid and throw in the R that is coming today and see what it does.

 

[Bdsankey]

I was fully on board with it being a mismatch of engine to k factor on the converter, and I gave up saying it has to be a fluid problem, until PI called and said it isn't the converter. I think it was around the time I put in the 12mm exergy that I started having this problem, so I thought it just hurt the vert.

I called a couple friends and they have SOLAS but no mechanical way to test the trans. I seem to remember Mike L saying the scan tools are useless and it ha to be mechanical.

My other "diagnostic" choice is to get some trans fluid and throw in the R that is coming today and see what it does.

That seems like a ton of labor to not fully diagnose the problem. I agree with James, if you think the issue isn't the converter then by all means take it to someone who is qualified/has the proper tools to diagnose it.

 

[Chevy1925]

I was fully on board with it being a mismatch of engine to k factor on the converter, and I gave up saying it has to be a fluid problem, until PI called and said it isn't the converter. I think it was around the time I put in the 12mm exergy that I started having this problem, so I thought it just hurt the vert.

I called a couple friends and they have SOLAS but no mechanical way to test the trans. I seem to remember Mike L saying the scan tools are useless and it ha to be mechanical.

My other "diagnostic" choice is to get some trans fluid and throw in the R that is coming today and see what it does.

you will need just a trans pressure gauge and the dumb 11mm adapter to the port. A tech2 to do commands and knowing what to look for would be very important as well. I dont know enough there to help.

 

[N2BRK]

So far I have a friend with a trans gauge. I can cobble together an adapter. One friend has a SOLAS with some sort of Allison software purchased, but no one was a Tech2 that I can track down yet. I can't wait to get out of work today, LOL.

 

[Evan@InglewoodTrans]

7/16 x 20 works in the pressure port. I think you’re chasing a issue that doesn’t exist. The K is in no way the right choice for your turbo (too loose) and a precision wont fluid couple at all so even in perfect condition the powers not getting to the ground unless locked up. I bet the R is much better experience for you. If the solus is up to date it should have all you need.

 

[N2BRK]

Thanks Evan. I’ll throw in the R and assume Precision gave me bad advice. I hope to get it swapped next week.

 

[Evan@InglewoodTrans]

Thanks Evan. I’ll throw in the R and assume Precision gave me bad advice. I hope to get it swapped next week.

If it makes you feel any better about swapping it even if you have some crazy ghost issues it’s a much better converter for your application for when everything’s 100% but I think you just have had a run of the wrong converter making you pull your hair out but I could be wrong.

 

[N2BRK]

I always say that educations costs - after this is resolved, I’ll have the education

 

[Mike L.]

I think you have less HP than you think you have.

 

[N2BRK]

I made 636 on Mark’s dyno on my stock cp3. It was holding 24.5k. Now I’m on a 12mm exergy holding 29k. I *think* I’m near 700.

 

[Mike L.]

I was under the impression you were making close to 800.

 

[N2BRK]

Stock block, no Ricky Bobby tune. I just copied my setup with my buddy and his LMM too. Mark did his in person too - 685rwhp. He and I both felt my truck was faster, and butt dynos never lie, so I’ll say I’m 700’ish. Lol

I plan to slap the R in next week. I could check pressure first. Looks like I can borrow the gauge, adapter, and choice of Solas or Modus. I need to search/read what to do with it all, lmao.

 

[N2BRK]

You may have been thinking of Kevin’s truck. He has a Danville stg1 engine, 68stg2r, and did 758 on marks dyno. He told me you did the R I’m his truck but he didn’t like it down low so you installed the K and you both loved it.

 

[N2BRK]

I got a fitting and performed the test. I’m seeing numbers much lower than the service manual I do I found online. Would y’all please weigh in if this looks like a problem? Thanks.

 

[N2BRK]

Key to pic:

Park at 600 is 120psi
Park at 1200 is 127psi
Reverse at 600 115psi
Reverse at 1200 is 240-270 (bounced a bit)
Drive TCC On 1200rpm 118psi
Drive TCC OFF 600rpm 115psi
Drive TCC OFF 1200rpm 127psi

 

[Mike L.]

Doesn't look right. At idle main mod will drop pressure 150 psi. At 1200 it should have gone full main pressure. What is the pressure in drive at WOT?

 

[N2BRK]

280psi in drive. On the nose.