Bellmouthed turbo inlet?

[ReQuieM]

So, I was thinking to reduce inlet restriction, would this be a good idea?;

Turbo inlet (3") - bellmouth off the inlet (4") - tubing (4") - Filter (big )

VS

Turbo inlet (3") - tubing(3") - Filter (big)

*sizes are just for an example - assume that (like 99% of GOOD aftermarket filters) the filter has a tapered of bell mouthed bottom where it connects to the tubing*

Heres some of my thoughts: bellmouths are proven to have superior induction ability. In both cases the tubing would act like a kind of plenum for the turbo compressor and larger tubing will allow more air to be available for the compressor.

So I think the first option would be less restriction BUT will it be one or two tenths of fk all better? Or will there be a noticable difference? I'm thinking it would help boarder line surge line applications...

A side thought, weld on the bellmouth or silicon connector?

All input bar stupidity welcome!

[ed]

turbo inlet - tube - bellmouth - filter

[ReQuieM]

two things, why?

and would by that rational say - a bellmouth based filter would be as good/best?

[ReQuieM]

second thought, what if the AR on the compressor was quite low? ie .5, would it make a decernable difference?

[JP]

I run bellmouthed podrams on two of my turbo cars, allows me to use a 6" filter. the podram is connected to 3" tubing that goes to the turbo inlet. Can't comment on how they compare to a plain straight 3" tube with 3" filter though as the podram setup is the only one I've ever run. I can say that they're really loud though.
I got my podrams from http://www.jntperformance.com.au/

[ReQuieM]

yup, I'm using unipod filters, which have ali bell mouths as the base of the filter.

I'm just curious to see if having the additional bell mouth at the turbo and the extra volume of the bigger tubing would make any noticeable difference in either response, spool or max flow ability.

[takai]

You should use a bellmouth whenever the ID of the piping changes significantly.

[ReQuieM]

yup but thats not really the Question tho.

Would a bellmouth at the turbo and then larger piping off it be better then just the standard sized piping from the turbo? both with bellmouthed pod filters...

[MrStroker]

i think results would vary greatly depending on application.
eg. where cold air enters the engine bay, how long a pipe from throttle to filter, if you are using a heat shield level with your bellmouths, what type of filter you are using, etc,etc.

In your specific application it sounds as if it would be better to have a short pipe between unipod and turbo as the heat from the turbo woud have a negative effect on the lifespan of your foam filter.
The pipe can be whatever length you determine to be best in terms of cold air feed, accessibility, heat produced from turbo, sound - shorter usually means louder, etc,etc.

I would also consider making/cutting a heatshield to prevent your air horn from sucking hot engine bay air from behind itself.

Realistically though my friend, the only thing that really matters on a turbo engine is the snail hanging off of it.

Peace

[ReQuieM]

Okie Dokie, for most of the responses so far I believe that I haven't made myself clear enough. While the language of words has failed me so I shall turn to the visual language instead for clarity



Assume the filters are the same size, a bigger filter will obviously be better then a smaller. Forget heat, assume both intakes have the same temperature air access.

PURLY on potential flow ability, which will be better? and by how much do you hypothesize the difference will be?

I hope that this is considerably clearer

[SillyCarS]

i wouldnt bother, get an adapter an put a monster filter on it

[SillyCarS]

here's mine

[wagonist]

A couple of things to consider:

Any changes to pipe size will cause turbulence
A bellmouth at the turbo inlet with a pipe before will cause more turbulence unless you have a reverse one to allow for a smooth transistion
The thing causing the most restriction is the turbo inlet size
The atmosphere has equal pressure

[ReQuieM]

A couple of things to consider:

1. Any changes to pipe size will cause turbulence
2. A bellmouth at the turbo inlet with a pipe before will cause more turbulence unless you have a reverse one to allow for a smooth transistion
3. The thing causing the most restriction is the turbo inlet size
4. The atmosphere has equal pressure

I hope you don't mind but I numbered your points to make discussion easier

1. Very good point!

2. How so? Wouldn't the bellmouth at the filter work well enough? considering that it would bellmouth into straight pipe (at the filter) then into outer most points of the inlet bellmouth? or are you saying if the larger size tube was literally like a plenum, having the same size opening as the compressor inlet for the filter, that the filter ended opening would need to be bellmouthed into the tube/plenum?

3. For sure, I was just thinking about this as a way of easing a small AR (inlet opening) by allowing greater intake efficiency. You know, make the most of what you have

4. you've lost me here? how does this impact? I realise that at sea level atmo is 14.7 odd PSI, a filter (any restriction) will equate to a "pressure drop", etc. But I'm not catching your point sorry.

I'm really just into discussing this from its theory side, fluid dynamics is an interesting topic, and has a huge impact on performance. So I like to get a good understanding of it. I mean if its a waste for this community to discuss just let me know and I'll put it to bed. I like the discussion that occurs from the group intellect that toymods have

[wagonist]

2. the bell mouth helps smooth the flow going from a large (usually infinite) amount of airflow at the filter. But if you start with a confined area, ie a larger pipe, to start getting the airflow to contract smoothly, you need a reverse bellmouth to start it.

4. the system will only draw as much air as the turbo can suck as there is a constant pressure at the start of the system.

In my way of thinking, you want as smooth a flow as possible at the turbo inlet so its aiming all its energy at the blades and not swirling around creating friction with the walls. As the limiting thing is the suction of the turbo, this is determining the volume of air, therefore the only thing that having a larger pipe before the turbo will do is have the same volume of air travelling through a larger cross section of pipe, which slows its velocity.

Fluid dynamics wasn't my strongest subject at uni , and I only studied it from a liquid civil engineering view, not a gaseous moving point of view like the Mech Engs did.
Gas brings in a whole new set of variables with compressibility, etc.

IMHO, you want to get the air intake to the size of your turbo inlet fairly quickly (to keep the velocity up) & make sure that any changes in pipe size are very smooth & gradual.
Have the insides of the pipes smooth to reduce the friction & boundary layer.

About the only thing I can see that would help is to try to get the air swirling (like how a tornado does) down the pipe as its nears the turbo so its already turning the same direction. This would reduce the force needed by the blades to change the direction of the air flow.

Considering that the OEM systems really only adhere to the smooth transistions of the pipes (generally), I would say that the other factors make neglible difference.
I reckon about the only thing