Turbo Bypass

[Jose Carlos Rublescki]

If you make the turbo run at vacuum, won't you risk over-speeding it and
consequently damading it?



>>Does anyone have any thoughts or references to info on the type and
>>positioning of Turbocharger bypass valves?
>>
>>Things I'm wondering about...
>>
>>- bypass to compressor inlet vs. dump to atmosphere
>>- pre-intercooler vs, post-I/C dump point
>>- effects on A/F Ratio
>        My first and best thought is AVOID USING BLOW OFF VALVEs IF YOU
>POSSIBLY CAN! How? Draw through a throttle body(s) into the compressor(s),
>and run the compressor(s) in vacuum at part throttle. No restriction points
>between compressor(s) and intake ports. Yep, you need to have the best
>compressor seal to do it this way, but it's well worth it. It becomes
>virtually impossible to put a properly selected compressor into surge, You
>will have much shorter spool up time (because the compressor will be
>spinning far faster as part throttle). You will have much lower exhaust
>back-pressure on the engine at part throttle, and consequently longer life
>and lower cruising BSFC (better mileage).
>        As far as I'm concerned a throttle between compressor and intake
>only happened because factories wanted to add turbos with a minimum number
>of part revisions and cheap seals. Yes, some of the early porsche race
>turbo cars did it to get better throttle response with relatively primitive
>design turbos. This is just not that much of a factor any more, and those p
>cars were pretty much an efficiency be damned design. If you really want to
>chat about efficiency and turbos, get hold of me off list (this is a bit
>off mission) and we'll talk about using long tube headers with turbos.
>                                        Regards :), Greg
>
>