throttle before or after turbo

[Greg Hermann]

>Old style carbureted turbos with draw thru carbs had decent throttle
>response but the volume of the intake was small, carb, turbo, manifold with
>no intercoolers, etc.  If you have a high performance turbo with high boost
>and an intercooler, lots of plumbing, etc, you definitly need to have the
>throttle after the turbo.  In that case, you also need a valve to prevent
>surging the turbo when closing the throttle after a high rpm run, say a
>shift.
>
>Gary Derian <gderian at cybergate.net>

Even with all of the above described plumbing, I doubt that the total
volume of plumbing is more than two or three engine revolutions worth of
air--so where is the problem with throttle response?? It was impossible to
run an intercooler with a draw through carb because of mixture puddling
problems. With port injection, no such problems.

Greg
>
>
>>At 12:32 PM 3/6/99 EST, WLundquist at aol.com wrote:
>>
>>>A better alternative is to put the  tb's before the turbo inlet
>>>so that when the tb's are closed the turbo will spin in a vacuum and
>maintain
>>>rpm, this will make for guicker recovery when you stab the throttle.
>>
>>Frederic mentioned poor trailing-throttle response as a possible drawback
>>to this approach... I personally don't believe that, for various
>>reasons, but the thing I do worry about is having lots of oil sucked
>>into the air in the turbo. How much of a problem is this, really? I
>>know some turbo vendors have special sealing options avilable, but I'd
>>like to hear from people who have set any old turbo up with the TB
>>before it, if you had much problem with sucking oil into the intake.
>>
>>The only reason I care this week is a weird turn of events has led
>>to the possibility that I'll get a turbo'ed car soon, and I'd like to
>>know, if I move the throttle before the turbo, how much trouble am
>>I asking for? Yeah I could get a new turbo/upgrade it/etc, but for
>>various reasons I would not like to have to do that.
>>
>>   TIA,
>>   Chris C.