6L80 / 6L90 Line pressure. Everyone is wrong

[dhoagland]

In your Log the dropping Airmass I believe just shows your torque management kicking in.
I don't believe that is dropping trans clutch pressures at all.

I would like to think its all predicted to drop during the shift.

I'm pretty sure you car was not Super Charged originally.
So If your Virtual Torque Model was never adjusted it would almost have to be off.

I'm also not sure how much the early E38 relied on the Torque model for transmission calculations.

[Jet Mechanic]

I'm a little out of my League here. I understand it but have no practical experience at it.

That being said you need to match Your actual torque to the Virtual torque model in your tune.
So if your Dyno sheet had torque numbers with Airmass that would be Awesome, I'm sure it doesn't.
You could probably use the chart against a hard pull, look at your Airmass and compare it to get an idea.

I know you can use the engine delivered torque in the scanner to give an idea of where your at.
But that also assumes all your air models and stuff are correct. I saw you are SD, I'm not sure if you need MAF to have delivered engine torque display accurately in the channels.

Where in North "H" Town are Ya?
I stayed in Decker Prairie from 09-14, working on Metro Rail extension Down Town.

I'm WAY out of my league....... and don't know if any of my info that I'm logging is affected by scaling? I did go into my tune and adjusted the y-axis up to 2200 and spark iteration increments to 5 to get me closer to the data I gave you and the numbers I see in the cells are over 2 times what my actual torque numbers are at the given airmass and RPM......SO, I still don't know where to go from here?!?!

You are correct, the dyno sheet does not have airmass.......

As far as Engine Delivered TQ.... mine will max out and stop at 640 lbft and the Trans Eng TQ maxes out at 885 lbft....so I don't know how to work with those limits.

I think I may try and find a local grudge spot and log a "track" style pull from a dig tomorrow since the weather is going to turn bad on Sunday.....

I'm located in Conroe.....38 Miles north of H-town......

[dhoagland]

Ha
I did the same thing...

Really need someone more experienced to chime in on scaling etc... and Airmass accuracy in your Tune.

Have you ever Logged Trans Channels to monitor slip?
If it was me that is what I would do before worrying about air flow and stuff.

If you have Slip then you can identify when it occurs and go from there
I'll try to dig up some Trans Channel configs that were given to me

[hjtrbo]

Your torque and pressure in the tune looks ok.

You really need expert help with this transmission. Adapts being disabled requires true skill to set up.

Try this, the first few shifts will be horrible. Turn the car off for 5 minutes and go for another drive. Should be closer on the 2nd drive. To be honest, I know nothing of setting up a built trans and running with adapts off. Personally I'd try and engage the services of someone like JustinWhiteTuned. I'm not sure how much he charges.

[dhoagland]

Your torque and pressure in the tune looks ok.

You really need expert help with this transmission. Adapts being disabled requires true skill to set up.

Try this, the first few shifts will be horrible. Turn the car off for 5 minutes and go for another drive. Should be closer on the 2nd drive. To be honest, I know nothing of setting up a built trans and running with adapts off. Personally I'd try and engage the services of someone like JustinWhiteTuned. I'm not sure how much he charges.

And maybe log these channels
But I agree, before you burn another Trans it would be worth calling in the Big Boys

[Jet Mechanic]

Thanks hjtrbo....and dhoagland.....

I'm going to try and make a couple "identical" style hits with some changes that I'd like to try....... and try to compare the data......

I also agree that I may have to get a PRO 6L80E tuner involved! It's just so damn hard to know who they are and how good they are........ talk is cheap, transmissions are NOT.....LOL

[dhoagland]

Thanks hjtrbo....and dhoagland.....

I'm going to try and make a couple "identical" style hits with some changes that I'd like to try....... and try to compare the data......

I also agree that I may have to get a PRO 6L80E tuner involved! It's just so damn hard to know who they are and how good they are........ talk is cheap, transmissions are NOT.....LOL

10-4
I understand, I like doing things myself. There is Tons of knowledge here.
I would think Circle D or Century would be able to recommend a good 6L80E guy.

There are mixed opinions about https://6l80etuning.com/
I have learned a lot on there. He will suggest PIDs to log, have you run and give you advise on his forum. He also remote Tunes so that might be a good option for you.
I know he is in tight with Circle D too
Post up a Log and I'll hit him up on his Forum.

[GHuggins]

Torque model is key for any modded vehicle with a 6sp to last. Main problem isn't so much the shifting or shift pressures - that can all be adjusted in the tune - personally I kill all tm and dial in the shift times and pressures for this - The main problem caused by the torque model being out is the "hold" pressure. This is most evident while driving in high torque applications cruising in higher held gears pulling slopes or hills where the trans would have been forced to downshift prior - now the vehicle pulls with ease, but doesn't have the increased line pressure to "hold" that clutch from slipping. You won't hardly ever notice an issue with wot shifting, but as pointed out the issue is with lower constant throttles with some of the prior mentioned spark and airmass settings...

You also need to keep in mind the torque model is going by "engine torque" and not reported "rear wheel torque" as shown on a dyno graph...

[cadillactech]

Well.....to answer your question directly on "fully built" ..... Mike Kurtz and Ronnie at Century Automotive and Transmissions in Richmond TX are very well known in the Corvette world for building 6L80E's for the Corvettes....They build these transmissions to hold 1600+ HP. My transmission has had every upgrade and update that is possible (for the power levels that I'm at). The only thing that I have not upgraded on my transmission is the planetary set. They offer a billet planetary set for my trans but didn't think it was necessary since I'm only at 811/787.....

As for the overfill.... Ronnie is the one that recommended a minimum of 1 quart (and up to 2 quarts) overfull..... He indicated that the worst thing that might happen from being too full, would be that the fluid would come out of the vent. He didn't think that aeration or foaming would be an issue because of the design of the trans......

You can find out all kinds of info on Mike and Ronnie on the Corvette forums and people's experiences and recommendations..... I'm just going with what I know and have been told. blindsquirrel brough that up in the comments above.... and the only way I can think of observing any foaming or aeration would be to put in a section of clear line in the cooling lines???

The main reason I'm on this thread is because I don't know how to determine if the comment that hjtrbo mentioned..."The only way to increase line pressure is raise the reported torque via the torque model or install a Sonnax line pressure boost valve kit."..... I don't know how to check or change the "reported torque" values in a Tune. Yet again... I think I have "clamping" (pressure issue) or possibly the transition time of the shifts may be allowing the slippage which is burning up the clutches and steels....

I posted my tune above.... for others to look at and see if there is something amiss..... and just like hjtrbo posted in his pic, MY pressures have been adjusted WAY up.....

I just spent the past 2 hours putting together a data logging channel that my car supports (2007 Corvette E38 PCM, T43 TCM).... and will data log everything the next runs at the track and maybe that will be helpful.

I would say mechanically you are probably ok but always good to rule that out.

If your pump wasn't damaged but the clutches were the only thing burnt up, I doubt your overfilled fluid would be the cause as the pump is the first thing to get fluid and would show signs of lack of lubrication if you had aerated fluid.

As the calculated torque increase so does your clutch pressure. If your torque model does not match the actual engine torque closely then you will have less pressure applied to the clutch during shifts to hold it from slipping, all other things being equal.

While you don't have an engine dyno sheet you could calculate reasonably what the engine is making from a chassis dyno in terms of torque to see if measured vs reported is matching up or how far off they are.

You can log all the shift pressures per clutch pressure control solenoids as well as clutch fill pressures, reported trans torque and shift times to watch and see if something is not right. Make sure to log gear ratio as you can tell if the current gear is slipping if the gear ratio is changing as you are locked into a gear.

You will want shift times to be quick to reduce the amount of slip and heat going into the clutches.

[kingtal0n]

I know when tuning my 4l80e w/ 411 Gen3 ,
The torque management was being subtracted from the transmission force motor current which was killing the shift pressure inappropriately.

For example during shift the torque management graph would say "Pull 25% power" and the look up table for that was lets say 15* of timing from the factory.
In the next table, it says something like "15* is worth 65% of engine power reduction" And there goes 65% of my shift pressure.

The way I got around it was by attacking it from every angle. I let it pull alot of timing for TM so the engine torque is substantially reduced (lowers chances of slipping clutches and preserves transmission parts). I also reduced the amount of % power per timing retard in the last table I mentioned, and reduced the amount of timing needed to pull for large reduction in power in the 2nd table (so it takes very little timing to report a large drop in power, which is true in forced induction setups, little as 2* can be worth 18% power), and finally adjusted the force motor current table to provide reasonable amperage drops for those WOT situations that I was comfortable with seeing (generally near 100mA for the 4l80e is 'safe'). I suppose if I acquired a 6l80 the first thing I would do is put a pressure gauge on it and learn how much pressure each gear should use from the factory, start there for reference values. Read the service manual for it and learn how the valve system works and what sort of boost valve and pressure valve behaviors it can display. Basically learn how to build one in theory and how it works. Then you will understand how to tune it, more or less. Whether or not big pressure is needed, or can be too much for longevity reasons, or whatever, is an issue of research and some trial and error wherever you are missing details or data.

[JustinWhiteTuned]

10-4
I understand, I like doing things myself. There is Tons of knowledge here.
I would think Circle D or Century would be able to recommend a good 6L80E guy.

There are mixed opinions about https://6l80etuning.com/
I have learned a lot on there. He will suggest PIDs to log, have you run and give you advise on his forum. He also remote Tunes so that might be a good option for you.
I know he is in tight with Circle D too
Post up a Log and I'll hit him up on his Forum.

i work with Circle d and did/do a ton of testing for the 6l platform and have two of my own cars one 1400 and one 1700 rwhp both living great with 6l90s. If you need help feel free to contact Circle d for a reference. I can get it right for you provided its mechanically sound without a doubt.

[TheMechanic]

https://forum.hptuners.com/showthrea...to-get-started

[Jet Mechanic]

i work with Circle d and did/do a ton of testing for the 6l platform and have two of my own cars one 1400 and one 1700 rwhp both living great with 6l90s. If you need help feel free to contact Circle d for a reference. I can get it right for you provided its mechanically sound without a doubt.

Hi Justin,
Thanks for offering up your services..... I went out and made some street hits and logged the data.... However, the street just won't hold the HP and traction.... I will attach a couple data logs. If you want to take a look at them and see if you see anything...... If I'm not logging something that would be helpful, let me know......

I did have to try and feather the throttle to try and make a decent hit..... So the logs aren't WOT like I would like....

Justin, where are you located in H-Town?? I'm in Conroe......and if you would like, send me a text of your info to 303-912-0733 Rod.........

[[email protected]]

This kit from Transgo has the recommendations for the transmission for HP Tuners and EFI Live. If anyone is interested in seeing the tables I will make a copy and post it. https://transgo.com/product-details/6l80towpro/

[sevinn]

This kit from Transgo has the recommendations for the transmission for HP Tuners and EFI Live. If anyone is interested in seeing the tables I will make a copy and post it. https://transgo.com/product-details/6l80towpro/

Found this in their instructions to save you a little trouble

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[Alvin]

This kit from Transgo has the recommendations for the transmission for HP Tuners and EFI Live. If anyone is interested in seeing the tables I will make a copy and post it. https://transgo.com/product-details/6l80towpro/

These instructions are not bad to follow. I personally like to keep the inertia adder working for "feel". It's important to set reasonable shift times in the TCM. These transmissions 6l-10L do not revolve around line pressure like the older 4L's. Good airflow models and appropriate shift times and retaining some torque management are key to good shifting 6+L transmissions.

[hjtrbo]

I watched the videos from the qr code link. Am I missing something? All they did was adjust the shift times.

[sevinn]

I watched the videos from the qr code link. Am I missing something? All they did was adjust the shift times.

I didn't even look, when I saw all they were referencing was shift times in the data I figured it was some incomplete stuff.

[Alvin]

I watched the videos from the qr code link. Am I missing something? All they did was adjust the shift times.

That's often all you need to do. You can get a granny shift or a tire roasting shift kit in a Th400 shift by adjusting just the shift times. focusing on pressure on a 6+L like you would a 4+L is the wrong strategy.

[TURBOSILVERADO11]

So on a SD tune you still adjust virtual torque to match engine delivered torque right?