Beefing Up Transmission - Torque Converter Question

So I'm going to bite the bullet and get my 10R60 built when I add the stage 5 turbos next month. I've been going back and forth on whether to get a stage 3 kit from suncoast or have it sent off and built at a shop like Level 10. Either way, I don't know if I need to address the stock torque converter at the same time. These are definitely outside of my wheelhouse. I see that suncoast has one for sale for the 10R60, and Level 10 says they replace the torque converter when they do your build.

The last time I did any real research into the workings of a torque converter was over 20 years ago for the 700R4 in my Firebird. I'm sure things are quite a bit different nowadays lol. So my questions are, is this a part that needs to be addressed when building the trans to handle more power? Is this a potential failure point, or will it be a bottleneck for performance if it's not changed out? If it should be changed, what stall speed should be used? You can choose your stall speed and with how fancy these 10-speeds are now, I wouldn't know where to begin choosing the correct stall for my application. It's 93 octane with all bolt ons and will have turbos as well. I'm assuming 500+ at the wheels. But the torque curve should still be pretty similar to most tuned STs. Any help/advice on this is greatly appreciated!

I wasn't going to build the trans at first, but talking to Adam at ZFG and he said he limits the torque by about 50-70 ftlbs when you are running a stock trans, and I want to get all that extra oomph unlocked since I don't have any ethanol around here so I'm already bringing a knife to a gunfight.

Even with upgraded turbos, 500 hp at the wheels is pretty iffy with 93. You say you talked to Adam who limits torque on a stock trans, but did you tell him you were sticking with 93? That amount of HP would need to be created by about 500 lb/ft of torque and even less than that if he's raising your shift points and rev limit. There are more than a few stock transmissions that seem to handle that amount of torque on e50.

He limits the torque even if you're stock on 93 with just a tune from what I understand. My logic is building the transmission up is worth at least that 60-70 lb/ft he's limiting from the jump. That, and a bit more confidence in hard launching without worrying about breaking something. I haven't seen any posts about fried torque converters or driveshafts snapping, and that's including the guys that are running full ethanol and low 11's/high 10's, so I was wondering/hoping that the stock torque converter is not only capable of handling the power, but is also already the correct stall to best make use of it. Would save me a couple grand in parts if I wasn't replacing the TC.

I'm trying to max out the performance on 93 octane with reliability as well. I know you are a big advocate of the single turbo swap, but I don't have a fab shop near me that I would trust with that job, and I don't want to send it to a shop a couple hundred miles away and have them do that big job, just to have the internals of the engine start failing with the increased power. I'm waiting on beefed up internals to become available before planning a big project like that.

The only thing left after the turbo upgrade will be the fuel system, and I've heard from a few people that upgrading the pump or injectors while still on 93 octane isn't necessary, even with the turbo upgrade completed. I don't know if that's true, but those parts are a few grand on their own, so I hope it is. What are your thoughts on that?

Thanks as always for the input!

You would have to ask Adam @ZFGracing about the particulars. It doesn't sound exactly right that he would make an e50 tune that would produce 500 lb/ft of torque, but limit a 93 tune to ~70 lb/ft less. Unless he's doing it because the octane and detonation/egt won't allow it. I don't see any way you're going to see that kind of torque from a 93 tune even with upgraded turbos. See what I'm saying?

I don't think making the transmission a bit more bullet-proof is a bad idea, I'm just saying that I, myself wouldn't bother until I broke something. And I don't think that is a common occurrence with a 93 tune. Study this post in my thread. The math that is presented there is based on the same equations used by Garrett and Borg-Warner. From that spreadsheet, I would say that with a compressor/turbine of the right "size", on 93, you might be able to handle a 2.6 pressure ratio on 93. That would give you potentially 62 lbs/min mass airflow which should be ~620 hp (give or take) at 6500 on gasoline- or about 550 at the wheels. That is nearly exactly 500 lb/ft of torque. If there are a lot of people out there running around at 500 lb/ft and the trans can take it, then it wouldn't be my go to. BTW, smaller turbos produce torque much earlier in the RPM range than larger ones. And due to certain physical characteristics, the more torque being made at lower RPM the more likely it is to break parts. Even the stage 5 bolt-on turbos are not that "big".

As far as the single turbo, my feelings are simple. By the time one has spent the money on the turbos, downpipes, exhaust, charge pipes, intake, (intercooler and tuning is a given in any scenario), et cetera, you've spent roughly the same amount as a well thought out single turbo upgrade would cost.

Yes, I would. At minimum I’d have it cut open and cleaned and rebuilt.

If you’re going through the hassle to rebuild the transmission, you wouldn’t want all that old oil or dirt mixed in that fancy new transmission.

these are not the greatest designed converters either from the jump.

520hp/540tq at the wheels here. Been beating the hell out of my car practically light to light non stop for over a year. Race anyone and everyone I possibly can. Stock trans has held up just fine for me. I think this is one of those things that probably makes more sense to skip until failure, they are pretty stout though as is.

Are you on stock turbos?

Yes.

I'm running an E50 tune on my '21 with 47k miles. I've been having 3rd gear slipping issues since I installed the E50 tune. I checked the fluid and wasn't low but I topped off to the max for our trans. Still having slipping issues, only in thrid gear. When I go full throttle in third gear it gets to about 4k rpms and it just lets loose and goes to redline with no acceleration. It's damn terrifying and only seems to happen when the vehicle is fully warmed up. I think it's worth beefing up the trans if you're running E50. I had zero issues with the 91 tune running E30. Might have to go back down to the 91 tune, sadly.

Well, there are trans options out there if you wanna plunk down the cash. https://www.puredrivetrainsolutions.com/ford-transmissions offers a 10R60 build (although their site only shows 10R80 rebuilds). I believe @hellhorseperformance has done a handful of 10R60 builds as well.

That suncoast kit seems pretty good.

What all is done to yours

It's in my signature.

Definitely. They do great work. I saw what they did the 10r80 converter and thought it was awesome.