Shaun@SG

Apologies for asking so many questions about Haldex recently. It's just that I need to clear all my doubts before starting on Project TT.

My question this time is whether or not the Haldex drive system that comes on the 225TT is electronically controlled in anyway. I am hoping that it is a PURELY mechanical torque distribution system because I am intending to ditch the stock ECU for standalone engine management system (Autronic) to achieve 400hp on a custom turbo/injector setup. I am trying to avoid running parallel ECUs because it is complicated.

Hope the ECU has nothing to do with Haldex control.

TIA

RTinNYC(again)

With the answers to your questions and those you haven't yet asked. As it is a software driven system, I believe the answer is "yes" and "maybe." Yes - it is electronic. Maybe - it functions in correlation with the central ECU. Here's the reason for the last - there has to be some communication as Haldex de-activates in ABS braking and ESP situations. Hope that kinda helps - good luck.<ul><li><a href="http://www.haldex-traction.com/">Haldex whirrlies galore this way...</a></li></ul>

JeremyTT

That said, it has a separate control unit/module. I believe that this is completely separate from the engine ECU.

As for going for really big HP, talk to sTTanford He has a pretty big turbo spooling on his engine at this point, is planning to use his stock ECU, and go with a secondary system, as well as a secondary fuel system due to the TT injectors being a special spray pattern. It turns out that the stock 225 injectors are the largest ones that will work without a completely custom solution.

Shaun@SG

Thanks Jeremy

After rTTexax gave me the haldex website, I went to take a look at it and was relieved to find that it operated seperate from the engine ECU.

Can you elaborate on the stock 225TT injector "special spray pattern" please? When you say "custom solution" do you mean custom solution intake manifold? Because as far as I know, injectors are pretty much injectors. The signal they work off is the same for all, so why would larger injectors only work with a custom control system?

Shaun@SG

Thanks man. Checked out the site and it appears not to be dependent on the main ECU since it has one of its own.

JeremyTT

The injectors have some sort of proprietary pattern. LarryTT knows more about this; he was the one who warned sTTanford that he'd need to go with a secondary fuel system for his upgrade. I believe that Siemens quoted a fairly high price to custom manufacture high-flow injectors.

I do know that it's not a problem with the intake manifold, although some here have had theirs ported/polished with positive airflow results.

Also, the Haldex should not be a problem for you; it is supposedly good to 600hp+ with no problems at all.

Sorry I don't have more information for you. Best of luck with your project, and keep us all updated as it progresses!

Shaun@SG

I'm planning to run Autronic standalone engine management and do NOT plan to run secondary injectors (just big primaries). Is there going to be any problem with this? What "custom solution" is needed to run injectors larger than the stock 370cc ones?

TIA

Shaun@SG

I only recently started posting on Audiworld since I started out with my friend planning this Project TT . You guys are really helpful.

Actual work will start around mid Dec and hopefully completely done by mid Jan. I'll post pictures throughout the process as well as questions if we should run into any problems. Thanks so much

Larrytt

This is what I have heard from another TT owner that is in the middle of a major engine build-up. He has flow tested the 225 injectors as well as tested quite a few Bosch and Siemens injectors. He has spoken to both Bosch and Siemens engineers about the 225 engine. The 225 has a special pattern to the spray pattern. The injector used in the 225 is the largest injector of this pattern to exist anywhere. If you were to step up to a larger injector, no telling what will happen to your combustion. You could run rich, you could run lean, but don't expect to get a perfectly metered burn as you currently are getting.

A secondary set of injectors can be used to add in more fuel at higher rpm levels and will be much safer.

Can you run LARGE injectors in place of the stock injectors? Sure. Will it burn out a valve or worse? Can't say with 100% certainty, but why risk it when the engineers that have developed the injectors say nothing sprays with the correct pattern currently exists without going custom for $400/injector?

As for the Haldex question. I don't know the answer to this and don't believe anyone here knows for certain. Yes, the Haldex has its own ECU, but the Haldex ECU has to be getting a signal from somewhere and in some way it has to be interacting with the main ECU in the car.

You are possibly best to leave the ECU in stock mode and run your electronic add-ons along with it. This will allow the other electronic components in the car to also operate properly without you having to troubleshoot something stupid that might pop up.

Hope that helps and no I can't give you any more info on the 225 being built. It should be running by the end of the year or the latest beginning of next.

Shaun@SG

The thing is secondary injectors require drilling the manifold. Would rather run larger injectors.

I don't see why it should be a problem running different spray pattern injectors when the other big power kits for the transverse 1.8T all use different injectors. Does this make sense to you?

On the ECU issue...looks like I'll have to run parallel ECUs.

Thank you for your advice