Going built engine

[shushikiary]

People also forget that with DI you don't have to suck the fuel past the valves, so you typically see a 12% increase in available air mass for combustion... aka a straight up 12% power adder just from going DI..... The cooling affect that E85 has with DI as well compared to port injection is also insane... you don't get the same 105 octane rating from PI as you do DI with E85. It's still poor mans race gas on PI, just not as effective. I've seen papers that show that the cooling effect from E85 is nearly 30% more affective in DI than it is in PI.

The only reason to drop DI is because aftermarket control solutions for the injectors used in the N54 is limited, but I don't think the advantages of going aftermarket ECU are enough to convince me to go PI only. There's also the option of a syvecs and still keep the DI, so if I absolutely had do do aftermarket ECU, that's the route I'd take over going PI only. Simply too many advantages.

Heck, I want to build a dart block 427 with a 4 liter super charger for a mid engine superlight weight (brand name) SL-C, and it's tempting to go to an LT5 based head just for the direct injection especially since Holley is now releasing DI control options for their dominator.

 

[ShocknAwe]

DI is specifically designed to be used with high and very high compression engines, especially the turboed ones for emissions as well as it allows the performance of a NA motor when not in boost due to the high CR but it mitigates against detonation as the fuel is only injected when needed, this is done just before TDC is reached and can only be done directly and with high pressure. If you delete it you will have to drop the CR in your motor which will be costly and nonsensical in my humble opinion. I am building my N55 now as well and I’ve decided to do DI ONLY there are now soo many upgrade paths available for DI that I think it would be dumb to eliminate it and go backwards.

Agreed. DI only.

 

[Hydra Performance]

Unpopular opinion here, but our piezo injectors are actually one of the best things about this platform, assuming they're working properly of course. At 2700cc/min @ 200bar they allow me the luxury of placing the injection window wherever I want, whereas with the solenoid injectors on the S55 etc you need to run very lean lambdas so as not to run out of injection window completely unless you add a lot of meth () or an auxiliary PI kit.

Definite 10% (at least) power loss from deleting DI... I haven't spoken about this much yet, but I'm running an 11.4:1 CR on my motor, which makes >100bhp/L naturally aspirated THROUGH TURBO MANIFOLDS. Try doing that on a DI-deleted N54, I dare you

 

[wheela]

Unpopular opinion here, but our piezo injectors are actually one of the best things about this platform, assuming they're working properly of course. At 2700cc/min @ 200bar they allow me the luxury of placing the injection window wherever I want, whereas with the solenoid injectors on the S55 etc you need to run very lean lambdas so as not to run out of injection window completely unless you add a lot of meth () or an auxiliary PI kit.

Definite 10% (at least) power loss from deleting DI... I haven't spoken about this much yet, but I'm running an 11.4:1 CR on my motor, which makes >100bhp/L naturally aspirated THROUGH TURBO MANIFOLDS. Try doing that on a DI-deleted N54, I dare you

I Agree with you

A clarification about s55 - Nostrum now offers a higher flow option they call their stage 3 injector that they claim flows 20.2g/sec @ 100 bar (1212g/min). For pump gas assuming a density of about 0.71g/cc that works out to about 1707cc/min @100 bar vs. 2700cc/min @200 bar for the n54 solenoid injectors. So there's now some really good potential and tuning flexibility with the s55 style solenoid injectors as well

BMW N55-S55 Stage 3 DI injectors

Nostrum provides high horsepower fueling solutions to the automotive

nostrum.mybigcommerce.com

 

[Hydra Performance]

I Agree with you

A clarification about s55 - Nostrum now offers a higher flow option they call their stage 3 injector that they claim flows 20.2g/sec @ 100 bar (1212g/min). For pump gas assuming a density of about 0.71g/cc that works out to about 1707cc/min @100 bar vs. 2700cc/min @200 bar for the n54 solenoid injectors. So there's now some really good potential and tuning flexibility with the s55 style solenoid injectors as well

BMW N55-S55 Stage 3 DI injectors

Nostrum provides high horsepower fueling solutions to the automotive

nostrum.mybigcommerce.com

Piezo injectors, by virtue of being solid-state construction & variable in lift by nature, will always have finer control (and a wider tuning envelope) than a solenoid injector. They are technically superior, and are also used on the most advanced turbocharged production motor currently in existence. (the AMG M139) These Nostrum Stage 3 injectors might as well be redrilled stock injectors for all I know, certainly nothing special at all.

 

[ShocknAwe]

I Agree with you

A clarification about s55 - Nostrum now offers a higher flow option they call their stage 3 injector that they claim flows 20.2g/sec @ 100 bar (1212g/min). For pump gas assuming a density of about 0.71g/cc that works out to about 1707cc/min @100 bar vs. 2700cc/min @200 bar for the n54 solenoid injectors. So there's now some really good potential and tuning flexibility with the s55 style solenoid injectors as well

BMW N55-S55 Stage 3 DI injectors

Nostrum provides high horsepower fueling solutions to the automotive

nostrum.mybigcommerce.com

Sure. Is this an argument to switch to S55 injectors? Even if it could be done, I prefer reproducible parts, and OEM is basically always best. What if nostrum goes belly up? I like knowing I can send in my two sets of index 12 piezo injectors for cleaning and get most of them back good as new and they will work as BMW intended. I in no way believe they downgraded the injectors because they were somehow better, it was because the piezo injectors on the N54 were too expensive to warranty.

Apologies if this was an incoherent rant.

 

[wheela]

Sure. Is this an argument to switch to S55 injectors? Even if it could be done, I prefer reproducible parts, and OEM is basically always best. What if nostrum goes belly up? I like knowing I can send in my two sets of index 12 piezo injectors for cleaning and get most of them back good as new and they will work as BMW intended. I in no way believe they downgraded the injectors because they were somehow better, it was because the piezo injectors on the N54 were too expensive to warranty.

Apologies if this was an incoherent rant.

No worries I probably wasn't clear, I wasn't suggesting converting an n54 to run solenoid injectors, just illustrating that platform also has DI injectors with similar flow capabilities as the n54 injectors, as I interpreted the comment I was replying to as suggesting s55 injection window tuning limitations were due to limited capacity of the injectors requiring a longer duration injection window

Edit: I agree with your sentiment of liking to stick with oem injectors. That's a big reason I'm not keen on adding PI or switching to PI-only.

 

[wheela]

Piezo injectors, by virtue of being solid-state construction & variable in lift by nature, will always have finer control (and a wider tuning envelope) than a solenoid injector. They are technically superior, and are also used on the most advanced turbocharged production motor currently in existence. (the AMG M139) These Nostrum Stage 3 injectors might as well be redrilled stock injectors for all I know, certainly nothing special at all.

Fair enough. I'm not in a position to argue which injector type is technically better, but I know s55 (and n55) guys seem to be getting good results DI-only using these injectors, so I thought it worth mentioning

 

[Dumaurier7]

I will be doing the Nostrum stage 3’s , upgraded Nostrum HPFP’s ( which I already have) and hopefully a Dorch lift kit all on the N55 so that I can max out the turbos and future proof the system as much as possible, I intend to show her all the love and keep her as close to OEM as possible! For the N54 I am keeping the index 12’s along with the overdrive, I intend to go as far as I can with this then if there aren’t better options I’ll add the PI, but DI will always be there for both!

 

[Brule]

Real world results for Direct injection vs Port injection are a bit different to the theories above.

The direct injection results have been on smaller turbos between 5558 to 6466 turbos which are similar at lower power.
The port injection dyno was on a 7675 turbo and had zero cam timing tuned.

Ive done 20+ dyno sessions on N54 with direct injection and have results for 1 N54 on port injection only.

On 8 degrees of timing direct injection makes 20.5kw per psi of boost
On 5 degrees of timing port injection makes 19.46kw per psi of boost.
Data from 7100rpm.

Calculations work between 12-17psi.
I have not been in higher boost yet.

Turbo size is a fair bit larger.
I do not see any conclusive results that Direct injection gains any power.
Tests data from E85 fuel.

Once I put more boost in I can compare more data.

Pump fuel I know the benefits but on e85 I see no benefit of having di or having a hpfp on a performance car.

 

[ShocknAwe]

Great feedback, but highlights the efficiency and knock resistance of E85.

Pump gas fanatics like myself will continue to rely on the piezos.

 

[Dumaurier7]

Sooo I’m confused (as usual!) if there is no benefit of one over the other why change in the first place? The way I see it if it ain’t broke don’t fix it, if the DI is working and parts are available for maintenance why change?

 

[Brule]

Sooo I’m confused (as usual!) if there is no benefit of one over the other why change in the first place? The way I see it if it ain’t broke don’t fix it, if the DI is working and parts are available for maintenance why change?

Once you reach a power level you need a proper traction control calibrations and better software to adjust everything.

Keep DI and just add port injection is great for 90% of n54 users.

If your on pump fuel keep DI as long as you can.

The amount of things you can do on an aftermarket ecu compared to oem ecu is drastically improved ten fold.

 

[Dumaurier7]

I’ve been in the stand-alone world for many years before ( Haltech, Vipec, Microtec,, Autronic, etc.) yes, they are very capable but there is a lot to get wrong as well. In my case I am not interested in undoing what’s already done and removing a lot of the other integrated features as my car is a streetcar (hopefully with the performance to rival that of a "Super Car") and WILL remain one as long as I own it.

 

[Hydra Performance]

There you go...
DI E85 has a higher airflow rate AND higher efficiency than an equivalent PI E85 setup at the same conditions, in addition to having a greater resistance to knock... Hope that settles it.

 

[carabuser]

The DI delete is an interesting project, but even in a perfect world where it idles right and drives as smooth as a stock car, it still uses more fuel and produces less power.

Using an aftermarket ECU for traction control has mileage though. The DSC in the 335i is very safety orientated, the Z4 system works a lot better but I don't think it's an easy swap. Neither are going to be optimised for a drag car though.

 

[Hydra Performance]

The DI delete is an interesting project, but even in a perfect world where it idles right and drives as smooth as a stock car, it still uses more fuel and produces less power.

Using an aftermarket ECU for traction control has mileage though. The DSC in the 335i is very safety orientated, the Z4 system works a lot better but I don't think it's an easy swap. Neither are going to be optimised for a drag car though.

The way I see it is that if the primary advantage of going with a standalone is being able to implement user-definable traction control strategies, would it not be possible to piggyback a standalone over the stock DME to have it control just traction + maybe 6x auxiliary PI injectors as well?

EcuTek's RaceROMs have a very nifty Custom Maps feature which allows the user to create maps with user-defined axes and outputs. How wonderful would it be to able to lower boost targets vs lateral g and/or steering angle with just a few clicks of a button and zero hardware changes? One can only dream...

 

[ShocknAwe]

How far is it possible to go with stock DME for traction control/DSC with a clutched diff? Staged boost targets by wheel angle like Chevy does with the Corvette and clever braking by the old ediff module?

Would probably need better brakes.

 

[Jern54]

I can confirm PI only makes less power after switching to Maxxecu
My car made 100whp less with same boost levels and a bit less timing advance to keep the knock sensors happy on a E70 mix.