[Diy_efi] RE: Throttling intake air -- references

[Lasse Langwadt Christensen]

Axel Rietschin wrote:
> ----- Original Message -----
> From: "Brian Michalk" <michalk at awpi.com>
> 
>>Therefore it does not make any sense (efficiency-wise) to have a
>>turbo working against a partially closed intake throttle body.
> 
> 
> The BMW F1 turbo engine worked this way, by-wire throttle before the turbo
> and no wastegate at all with an enormous turbine housing, but this engine
> was known to have a *huge* turbo-lag and a narrow powerband making it almost
> undriveable.
> 
> Modern state-of-the-art turbo engines (WRC and CART) have port throttles,
> very small turbine housings, massive (and aggressively opened) wastegates,
> no lag and wide powerbands. 

If BMW  did ~1000bhp on 1500cc and the WRC does ~300bhp on 2000cc could
that be part of the explanation for the smaller turbo and lag?

Could the wide powerband be that the output is "railed" at ~300BHP
because of the restrictor so that you just can't "see" the peak?

Is the big waste gate needed to prevent the turbo from spinning so
fast it falls apart?

> The current 12'000 rpm Cosworth CART engine also
> has a 9th by-wire throttle just before the plenum chamber, not sure what it
> is used for.
> 

could it be used to keep the boost right below what will trigger the
pop-off valve ?

-Lasse




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