# Conversion to Direct injection/ FSI



## laminaytrap (Oct 31, 2009)

Hey,
So i was thinking about this the other day and it doesn't seem that it would be very hard to use some sort of SEM to emulate direct injection as seen in the new FSI/TFSI VAG engines. There would be a bit of fabbing and lots of tuning, but has anyone done this? Or has anyone looked into it at all, i couldn't find anything on here, or much anywhere else for that matter.

Jon


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## ValveCoverGasket (Mar 20, 2002)

if the injectors are anything like diesel injectors (and i beleive they are...) youll need very special injector power boosting circuits in order to operate them - no SEM that im aware of currently has this.

youll also need really accurate injector mapping... significantly more detailed than just "42# injector" for example.


these are also the same reasons you dont run across many aftermarket diesel SEM systems


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## Prof315 (Jan 5, 2009)

laminaytrap said:


> Hey,
> So i was thinking about this the other day and it doesn't seem that it would be very hard to use some sort of SEM to emulate direct injection as seen in the new FSI/TFSI VAG engines. There would be a bit of fabbing and lots of tuning, but has anyone done this? Or has anyone looked into it at all, i couldn't find anything on here, or much anywhere else for that matter.
> 
> Jon


There is a serious catch to FSI, direct injection requires much higher fuel pressure and thus the injectors require a lot more power to open. As far as I know NOBODY in the SEM market supports direct injection as of right now. I know for sure that all of the grand-am and world challenge guys running VWs are running custom reflashes on stock ecus.


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## ValveCoverGasket (Mar 20, 2002)

and speaking of diesel SEM...
when bruce and al stopped by our neck of the woods here last year, i asked them about whether theyd done or looked into any diesel SEM work... and they mentioned that they were working with an east coast university (in maryland maybe? i cant remember...) and had some prototype stuff running but it was still needing to pull wall power in order to run the injection circuits... so they were missing the boosting circuit still.

granted, this was a year ago, but it was promising to hear that someone was actually working on it :thumbup:

although, in talking to some of the folks at work here whove done circuit design for things like this, getting the injection circuits correct is difficult even at an OEM level with teams of engineers.


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## Prof315 (Jan 5, 2009)

One possibilty would be to grab the injector driver step up box off of a Duramax deisel. It's external and mounted right on the engine. HMMMMM


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## ValveCoverGasket (Mar 20, 2002)

yup, ive checked that out too... and theyre werent too expensive either, couple hundred bucks from what i could tell for used stuff a couple years ago.

then you only have the injector mapping left... which might be more tricky...


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## Prof315 (Jan 5, 2009)

Yeah cause you need dead times and voltage offset to be perfect.


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## laminaytrap (Oct 31, 2009)

So using existing hardware and some creativity with relaying and code hacking this is possible? The part i don't understand even after all the reading and studying diagrams is how they are able to inject the fuel at "the top of the compression stroke" while it is clear in all the diagrams i've studied that the injector is behind the intake valve? This is confusing me above all.

So the question is beyond the fancy injectors and tough tuning are there any actual mechanical differences between a diesel/fsi/na engine? Such as injector placement, valve overlap, Mechanical timing in general?

Thanks,

I'm glad you guys actually take an interest in this kind of speculation

edit* maybe i'm wrong and it just inject directly into the chamber/


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## ps2375 (Aug 13, 2003)

Your last statement is correct, the injector injects directly into the cylinder, part of the reason they went back to 4 valves per cylinder, no room for 5 valves, spark plug and an injector.

One of the other problems I've heard mention of is the possible carbon build-up on the back of the intake valves due to poor PCV operation and the lack of fuel "cleaning" them. Kinda like what happens to the TDI's intake manifold filling with buildup. And with a plastic intake manifold, it will not be cleaned like the TDI manifold is able to be cleaned.


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## ValveCoverGasket (Mar 20, 2002)

laminaytrap said:


> edit* maybe i'm wrong and it just inject directly into the chamber/


thats exactly how it works, hence the diesel-esque fuel injectors 

and i think the intake valve fouling would be less of an issue (probably not an issue at all actually...) in a project motor like this, as youd probably just end up running an open crankcase vent anyway.


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## ps2375 (Aug 13, 2003)

ValveCoverGasket said:


> in a project motor like this, as youd probably just end up running an open crankcase vent anyway.


That is true, but I am curious to see how this works out over time with all the DI motors from various brands available now.


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## need_a_VR6 (May 19, 1999)

Injection timing and charge prep in the intake tract are critical. There's talk of MS3 supporting FSI at some point (with external drivers) once the angle clock is implemented in the next big code rev.


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## ValveCoverGasket (Mar 20, 2002)

need_a_VR6 said:


> (with external drivers)


this would lead me to believe they gave up on making their own boards for the injector drivers?


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## need_a_VR6 (May 19, 1999)

I think they were going to leave it up to the interested parties to figure it out. Can't be that hard...:sly:


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## ValveCoverGasket (Mar 20, 2002)

need_a_VR6 said:


> I think they were going to leave it up to the interested parties to figure it out. Can't be that hard...:sly:


:laugh:

its the hardest part


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## need_a_VR6 (May 19, 1999)

Just electronics!


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