throttle body before turbo?

[brett_celicacoupe]

im just trying to explore options for a future twincharge project. i tried google searching this with no specific information found.

so what im asking is; is there any major problems/side affects with having the TB before the turbo?


even if someone has links to useful information that would be good

will there be any negative effects of having such a large amount of piping before the engine BUT after the TB? will this be equivelent to a massive plenum volume?



ie. the setup will be similar too;

.....................bypass valve v
TB => Y pipe ^ => SC => turbo => IC (largeish size) => engine


thanks

[Whiplash]

basically with having cooler piping you need to estimate how long it will take for the turbo to fill the piping, cooler and plenum to the set psi level. basically the larger the piping and area the larger you pressure drop will be. this is basically experianced on manual cars not nessasarily auto as the revs on an auto will always be up on spool and little pressure drop would be experianced

as with having the throttle in front of the turbo there shouldnt be any problem with it. i myself have a butterfly in front of my turbo on my patrol but that is a deisel so dont knw how it would behave in effect of the petrol. it is however a decent idea to do so as you woulnt experiance any back spin on turbo as there is no pressure bounce off the butterfly and therefore no need for a BOV.

[o_man_ra23]

True on the pressure bounce etc, but having the TB before the turbo, you may get vacuum pockets in the air entering the turbo due to the turbo sucking from a small air supply when the butterfly is completely closed. You will have some bypass around the TB for your idle control, but this may not be enough if you snap the throttle shut from high RPM. This may cause turbulence within your turbo and destroy teeth. Could be a low possibility, but murphy sez youll be the guinea pig. I would say not a good idea.

Cheers, Owen

[Whiplash]

true never thought of that! i personally dont like the idea of doing it on such a high performance engine or with a turbo and supercharger setup. its just more stuff to go wrong. i have not seen one car come form factory with tb before turbo so that must mean something and with reasoning. i am actually changing the tb position on my patrol to go after the turbo so that it isnt in front of the turbo due to the fact that when ideling it throbs like anything and think its due to the turbo starving of air

if i was you id just leave it in original position. instal a bov to reduce preassure bounce and be done with it.

what was you reasoning to wanting to do this in first place?

[brett_celicacoupe]

just looking at all options for a twincharge setup

[Billzilla]

BMW tested a heap of configurations and found that they got the best driveability with a primary throttle in front of the compressor, as seen above, in their 1400hp+ turbo F1 engine. They also fiddled with an additional four throttles in the inlet manifold.

[triptek]

Edited!!!!

[brett_celicacoupe]

this thread has nothing to do with superchargers!

[o_man_ra23]

BMW tested a heap of configurations and found that they got the best driveability with a primary throttle in front of the compressor, as seen above, in their 1400hp+ turbo F1 engine. They also fiddled with an additional four throttles in the inlet manifold.

Did they have any failures with this setup?? because if they had to put in several man-hours of R&D to overcome any problems, chances are they wont make the documentation for this available to the public, in which case failure is likely to be experienced if performing this.

Cheers, Owen

[triptek]

As oman ra23 already said you would create a huge vacuum in the ic piping, so you wouldn't be able to run an intercooler. Or the car would just stall.

Just asked an old mechanic mate and he said you'd have to use a carbon sealed turbo or you'll just blow the seals on the turbo and start blowing smoke on the first start up.

[MWP]

I thought all the older production cars that were made just after turbos became popular had TB before turbine?
Also remeber that suck through carb turbo setups also have the TB before the turbo.

I think the reports of it killing turbo fins is exagerated.
The only reason it isnt done more often is simply because it doesnt perform as well on the street (it lags more).

[brett_celicacoupe]

thanks for the advice



rep coming your way .....soon

[Ben Wilson]

I thought all the older production cars that were made just after turbos became popular had TB before turbine?
Also remeber that suck through carb turbo setups also have the TB before the turbo.

I think the reports of it killing turbo fins is exagerated.
The only reason it isnt done more often is simply because it doesnt perform as well on the street (it lags more).

The old Sigma turbos used to run a suck through carbie and they went OK once they came on boost. You will need a carbon seal to stop the seal getting sucked out once you close the throttle and lag may well be an issue. Getting it to idle nicely will be 'tricky' as well....

[o_man_ra23]

So its pretty well agreed that its old technology, and not viable with turbos that have pressure sealed bearings. Maybe ok with ball bearing turbos?? Still the issue of rough idle though. And as I stated MWP (not havin a go at ya), murphy sez that itll be brett that cops the freak broken fins.

Cheers, Owen

[Whiplash]

yer seems like it is the main problem with the setup on my patrol then. in mornings it always dies as soon as i put my clutch in and come to a stop. but once it warms up its fine. shall be changing that soon enough and will let yas know how it goes. and believe it or not a turbo shop did that haha