Ultimate FI Setup 2

[NcBlueTJ]

I know that modern formula one cars use fuel injectors mounted above the individual throttles that spray fuel directly down into the intake trumpets (I beleive they are called standoff injectors). This seems like it would be ideal from a fuel atomization/vaporization standpoint seeing as the fuel has the most time and space with which to mix with the air charge. Although direct gasoline injection is banned in F1, would they use it if they could?
I understand the ability of GDI to produce stratified A/F ratios and run lean without producing dangerous cylinder temperatures, therefore acheiving better fuel economy (like the audi R8 race cars for example). But does this ability come into play at WOT? I also understand the concept of acheiving greater VE due to the air charge entering the engine being pure air as opposed to an Air/Fuel mixture. Thus the engine is able to ingest more air for a given head flow rate, since the fuel is added later. However, during a WOT scenario given a high performance engine such as an F1 car, do these advantages outweigh the presumed loss of air/fuel mixing that a standoff injector would provide?
Sorry for the long-winded post. My basic question is this: Would F1 use GDI if they could and why? Thanks

 

[TDIMeister]

It's the very cooling that's partially responsible for the knock control. And last I checked, detonation is most severe just lean of stoic.

 

[Lou Scannon]

Agreed, TDIMeister.

 

[mattsooty]

Maybe you are misunderstanding me or just not reading my post correctly....

Slightly lean of stoich. the propensity to knock is increased, as the surface temps of the combustion temp increase.....

BUT

The SEVERITY of knock increases slightly rich of stoich. as there is more chemical energy within the charge.

MS

 

[Lou Scannon]

Slightly rich of stoich is not where high output boosted engines are tuned at WOT - they are tuned significantly rich of stoich).

 

[patprimmer]

Certainly those that retain intact pistons are tuned significantly rich of stoich.

Regards

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[mattsooty]

In the world of OEM Calibration/P&E Development Knock is controlled with spark retard. This retard may then cause the exhaust temps to increase & it is this side effect that is then controlled with enrichment.

Having said that, with modern GDI systems a stratified charge can be used for knock reduction. Keeping the majority of the injected fuel within the centre of the combustion chamber.

MS

 

[jimmy8v]

TDIMeister:

You mention a paper by dr Ulrich Baretsky regarding their direct engine technology. Would it be possible to email me a copy of said paper? It sounds like very interesting reading.

Many Thanks.

 

[TDIMeister]

I would if I knew to what address to send it to. The forum mods don't like posting of personal contact info of any kind.

 

[patprimmer]

I strongly suspect the forum management would take a dim view of anything like a conspiracy to breach copy write also as it would leave them vulnerable to legal action.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[jimmy8v]

My apologies. patprimmer, I appreciate your view.

IDImeister, please ignore the request.

Thanks.

 

[turbocohen]

One of the benefits of injecting into the rarefaction created after intake valve clodure on an F1 engine is the heat of vaporization which improves ve.

 

[turbocohen]

Forgot to add that the Honda approach to upstream injecting their F1 engine helps with detachment of the boundary layer additionally it reduces lag time when the atmosphere gets its turn to push air across the intake valve.