Bellmouthed turbo inlet?

[ReQuieM]

Velocity is a great point, I hadn't considered the larger tubes effect on that! Also I get what you mean by constant pressure now. Don't mind me

Yup, you would probably have sold me on it being a negative until I had a brain wave.
http://www.snortperformance.com/T3_60_1%20turbo.JPG

Note the inlet on the compressor housing. Bellmouthed, to allow for a larger diameter tube! I know not all turbos have this inlet. Thats a t3 off some description, this is a t04e without;
http://www.snortperformance.com/GARRETT%20T3_T04E.JPG

I'm seeing alot off the newer designed compressor housings with a bellmouth styled inlet, some with the surge protection grove etc, but its the taper that interest me for this discussion. Going by garretts site (assumign the pics are up to date) the mid framed turbos (t28) seam to the ones that get the bellmouthed compressor housing, although most don't... there are about as meany that have an addition ring around the inlet that the you silicon the tubing onto.

Most of the greddy, hks and turbonetics units appear to have the 'built in bellmouth'. I'm guessing the best way of replicating this would be weld on the bellmouth but would silicon joiners with a short bellmouth replicate then effect enough?

I'm guessing that any benefit from the bellmouth would come from the bell mouth starting effectively from the tips of the compressor blades, having a straight section in-between would negate the benefit. The next thought would be replicating the 'twin ring' inlet compressor housing design. would there be any percival benefit for the larger outer ring/tubing? I'm assuming it wouldn't, based on the restrictive induction ability of a straight cut tube and the point on the velocity.

Hmmm... thoughts?

[Big rob]

I can't comment on the effective difference, however I can offer an alternative. As others have already stated, any transition between diameters (especially over short distances) is going to lead to flow separation and contribute to boundary layer effects.
This can also be caused by transitions between two adjacent pipes such as connecting your intake pipe to the turbo inlet with a silicone joiner. The connection will have two sharp edges disturbing flow.

An alternative to your suggestions would be a long taper at 7 degrees or so between the turbo inlet and and filter with smooth long radius transitions where the pipe is constant diameter for clamping.

Otherwise a bellmouth on the turbo with a large diameter pipe, significantly larger than the turbocharger inlet to act as a plenum. This option would have no physical connection to the bellmouth itself.

[takai]

Plenum near the airbox and piping to the turbo of the same ID of the turbo inlet will theoretically be better, gives the disturbed air flow more time to settle.

In reality it will make a poofteenth of difference.

[phat22]

Mate, at the end of the day it will make a poofteenth of difference but......

I work on jet engines, basically the largest turbo there is! From this i have learnt that at the end of the day, you just need to have the inlet as smooth and linear as possible. A bellmouth on the front of the turbo is essentially just the same as the inlet of a jet. It has a smooth curved front edge and in some cases actually increases the diameter of the inlet as it gets closer to the first stage of compressor. What this does is 1 - provide a linear flow and 2 - slightly increases the pressure of the air being induced in the front. Larger diameter = reduced velocity = increased pressure in a subsonic gas. Sounds a bit back to front, but at speed, moving air does some crazy shit! Like what people have said already, the shortest induction you can have is the best. A large pipe beforehand will only create a drag situation and although having a slightly higher pressure, will be turbulent and "dirty" air. If you do this go much larger to create a plenum style intake.

Air can't turn sharp corners. Like you commented about the pic of the turbo it has a slightly chamfered inlet which ensures that the whole frontal surface of the compressor wheel gets a nice gulp of air. But if you have that going straight to atmosphere you'll find it won't be efficient because the air rushing in from around the inlet cannot bend around the sharp outer edge of the inlet and only about %80 of the compressor will get linear air. If you put a bellmouth on front of that, it allows the air from around the inlet to bend around the nice smooth curve and enter the turbo with %100 coverage. Make sense?? Bit hard to explain without pics so....

Hopefully the attachment worked.....

http://www.toymods.net/forums/attach...1&d=1248007107

After ALL of that, there is a million other little things that will affect it slightly but if you have a bellmouth into a plenum of prefiltered air like big rob suggested, awesome, cos it's atmo pressure air fed cleanly into the compressor.... or at the very least a bellmouth off the filter to a short three inch pipe straight onto the front of the compressor inlet, it should work ok as well, certianly well enough for an everyday driver turbo car.

Note: This is just my opinion based on what i've learnt. Feel free to relearn me if you don't agree, cos it's not gospel just how i've interpreted it and tried to explain! If it's already been said, sorry....missed it! And let us know what you end up doin!

[phat22]

And to answer the question directly......if it must be one of those two exact designs, the second one is better!

[takai]

And to answer the question directly......if it must be one of those two exact designs, the second one is better!

Sure, as the design gets larger the percentage losses get larger too. But in this case the limiting factor wont be the Ve of the turbo it will be the Ve of the engine.

Anyway, ill give you rep for your diagram, its pretty classic.

[ReQuieM]

Thanx for the replies guys, this has all been the kind of feed back I was chasing

Phat; I knew about the 'happy air' (I lol'd) which is wear this crazy idea came from. This wasn't so much for a specific instance more just a thought, but when I get around to fitting an after-market turbo I'll keep this in mind.

I was expecting that the difference would be 1 or 2 tenths of fk all, and going by peoples responses of a 'poofteenth' that works out to be closer to one tenth of fk all (1/10 fkall = .876 of a poofteenth) then two so it's not realy worth it

[ed]

http://www.profblairandassociates.co...mouth_Sept.pdf