GMBALL

Had to send turbos to specialized workshop, because there was damage to them. Now they are back, final assembly in progress.

JohnLane

OP....

Few notes..... I understand your frustration in the project you took on when your Bent Eight blew up.

Were it my project....

It would get crank steered rods; longer then stock if possible. Dimensions inside the engine don’t have to be as standard. Stroke stays the same, but a smaller diameter wrist pin that is wider, and shoved up as far into the piston as possible can allow for a longer rod which does good things. We are already giving it custom pistons, rods and liners and you have paid handsomely for them. We can specify what we want built and piston manufacturers will gladly produce them. I have used CP in the past. Most of the time they start with an off the shelf piston and make a few changes. Same with rods. Pick an American V8 rod that is similar dimensionally and a few machine steps has a custom that is just so.

I guessed turbos would get attention. Just a little more effort has bigger turbos that are well within the efficiency map for bigger power.

I hope that when you finally get the car back she runs great and you fall in love all over again.

I tip my hat to you sir... Your thread has much that is valuable for others to read in the future.

Best wishes.

GMBALL

Thank you for your kind words. I am getting the car on the weekend.

GMBALL

Update: took delivery, engine break-in period for me now.

BlownV8

Hope all goes well and you fall in love with it again.

PeterUbers

Good luck and let us know how it's going as you have faithfully done so thus far. Thank you for your contributions

GMBALL

First 200 miles are done. First 50 miles with Xentry MB diagnostics. Showed one missfire (faulty counter) on cylinder 5. Additional 150 miles done - no issues. Decided to change oil after 200 miles. There is a VERY strong smell of gasoline in the engine oil + filter. Otherwise oil is very clean, temperature is good, no issues. But there is this smell. Mechanic says to try and deactivate renntech ecu and see if the smell is still there on a new oil. What do you guys think of this smell? I am worried about it. Otherwise oil consumption literally none, no smell or smoke from the exhaust.

I.T. Guy

How are O2's rich or ok?

GMBALL

O2 ‘s were OK. We had a xentry plugged-in while driving and logged all issues. Besides one missfire that didn’t produce a check engine light, it was all right.

billvp218

Seems really unlikely to be the tune.

https://shieldoils.com/engine-oil-sm...oms-and-fixes/

Cifdig

these are new injectors? Or your original

GMBALL

Update:
- smell of gasoline faded away after another 100 miles
- engine oil now smells just fine
- new injectors, pumps, everything
- turbos were “refurbished”
- we have now much greater problem - gearbox

Engine is perfect, very strong, with all new parts like injectors, pumps etc - the power and torque probably went a little bit up. I can feel it, car is insane. Previously there was 740bhp on the dyno, now probably would push more.

Unfortunately gearbox can’t handle it, if you give 3/4 gas on 1, 2 or 3 gear, it is slipping like crazy. And even sometimes it disengages gear to preserve itself. Diagnostics show a fault within TCU that says something along the lines of TORQUE VALUE TOO HIGH.

Mind you, I have a TCU tune from Weistec. I will change the oil in the gearbox today, but I think the problem will stay. The torque is probably getting above 1200NM and that causes such behavior.

So I got the car with a perfect engine and now gearbox is giving up.

Cifdig

can weistec give you your tq limits? If not I advice getting a new tcu @5soko will explain everything. Your tq isn't reaching 1200 because the limits aren't set that high. What's happening if this is your issue, Your limits are probably close to stock and your hitting that threshold fairly fast . It takes much more boost and timing to achieve 1200 ft lbs. . And your tcu would have to be completely open to achieve those limits which won't happen unless your running big turbos 37 psi and 17 degrees plus with race gas or e85 and even that's questionable . Just food for thought . Congratulations on the build bro im sure your gonna enjoy her

GMBALL

Here is my request to Weistec:

I have a TCU tune from Weistec for M157 Mercedes S63 AMG Coupe. I have modified the car with ECU, downpipes, full racing exhaust, blackboost cold air intake, turbo-back bridge pipes between turbo and exhaust. Everything worked just fine with Weistec TCU.

I recently did a full engine rebuild with forged internals, new pumps, injectors, etc - and it now pushes even more power and torque ~ 760bhp and 1200-1250nm of torque, and I have a problem with gearbox.

Unfortunately gearbox can’t handle it, if you give 3/4 gas on 1, 2 or 3 gear, it is slipping like crazy. And even sometimes it disengages gear to preserve itself. Diagnostics show a fault within TCU that says something along the lines of TORQUE VALUE TOO HIGH.

I think your tune doesn’t allow torque of more than 1200nm for the gearbox. But in reality I have probably up to 50nm more.

Can we modify my TCU to increase the limit? Otherwise I can’t really use the power.

My VIN below.

Thanks in advance for your help!

Here is their answer:

We set the torque limits to 1200Nm but that really is just a number that does not always correlate with the actual torque that is being made.

What it will actually handle depends heavily on your driving style. People that launch their cars a lot are more likely to break output shafts. Aggressive ECU tuning with heavy torque manipulation will result in excessive clutch pack wear.

The two primary purposes of the TCU tune are to increase the TCU torque limits and increase system pressure which results in more clamping pressure and slightly faster shifts. The increased clamping pressure helps increase torque capacity of the transmission slightly.

What it does not do is fix issues where the transmission is not able to shift properly. What you are describing sounds like either an issue with the valvebody or the engine is over revving, causing the transmission to go into neutral to protect itself.

Over revving can be caused by worn clutches that slip and allow the engine to rev too high before the next gear can fully engage. Another possibility is when driving in M mode and the ECU tune sets the rev limiter too high.

As I explained previously, that is just a number that does not always correlate with the actual torque that is being made.

What you need to check is how much torque your ECU is reporting to the TCU. That is done via datalogging. If your ECU is greatly under reporting torque, that will cause slip. If your ECU was actually reporting 1250nm then the transmission would work appropriately and simply request the ECU limit power.

PeterUbers

Can you go back to stock ecu and tcu settings just to make sure the hardware is ok?

you may have already done this and I may have missed that in the discussions above ☝🏽

GMBALL

Yes, I did remove the ECU tune and transmission didn’t slip. With ECU tune the car feels insane, more violent than before, but transmission either slips or it completely disengages gear into neutral. I did change the transmission oil today (2 years old) maybe it will help. But I feel like some parts are probably worn out.

PeterUbers

did you lose traction? After my tcu tune when I would launch hard I would lose traction and the engine/trans would disconnect prolly cuz my engine over revved....

before this whole thing happened you said you enjoyed the tune and did you have any issues with slipping? Is this a more aggressive tune than before the engine work?

GMBALL

It might have lost some traction, but the traction control light didn’t come on + I didn’t even WOT. But this over rev hypothesis might sound plausible.

The thing is that it slips in the middle of rev range, between 3-5k rpm, so it’s nowhere near the shifting point.

Before this whole thing happened I put about 40k miles on this tune. It’s the same tune - renntech stage 2 tune, they ship their piggybox to you from the US, you connect it to OBD port and it flashes their tune to your ECU. It works only on my VIN.

Maybe my clutch pack is worn out? But then again, before the incident, it didn’t slip. Meanwhile the transmission was stored, so nothing could go wrong. Maybe the oil was too old.

kevm14

How much extra power and torque do you think you are making compared to before?

PeterUbers

perhaps the old engine was pulling timing for all the poor health issues it suffered from until it died .. the trans and tcu was happy and you were none the wiser.

now you have a healthy engine and perhaps it's revealing your drivetrain weaknesses

something seems odd though, I don't know enough about re installing a trans and rebuilding engines to know if this could be an installation error simply

I.T. Guy

My dealer “adapted” my trans a few tines over the course of my ownership and re-set the wet clutches. Could it perhaps be as simple as that?

Does Renntech have a TCU tune that matches their stage 2? I think what Weistec is saying makes sense - The torque reporting needs to match between the two ways ECU and TCU are handling / working with additional power.

GMBALL

I have changed the transmission oil and have reflashed the transmission tune from Weistec. It behaves significantly better during normal driving (very smooth) and I tried one 3/4 gas acceleration in 4rd gear and it didn’t slip. I will drive for a few more days and let it adapt and then will try a couple of runs.

I think there is no possibility of error regarding the installation, it is pretty much plug and play.

I do think that the engine is now healthier with about subjectively maybe +20 bhp and +50nm, feels more alive. Maybe drivertain is now a weak point.

GMBALL

Update: after oil change in the transmission, and after tcu reflash from Weistec it seemed to stop slipping under same conditions. Really strange how much change a new oil can make….

PeterUbers

what if it was just the re flash?

glad it's better - so, are you keeping the car?

GMBALL

When I was doing a reflash of TCU, the SW showed a notification that it detected a tuned file. This means that TCU already had a tuned file in it. So I assume it was okay SW-wise, but who knows what might have happened with TCU during 10 months of sitting disconnected. But I really doubt that SW was the reason. It’s like when you switch off your iPhone for 10 months and then switch it right on, it should work just fine.

No, I am not keeping it. I will sell it this year, already put the ad online. I am thinking of replacing it with a 2-gen low mileage Bentley GT.