V mount why only on RXs ?

[Prof]

So much \'hot air\' talked about intercoolers ! :Laugh
 
Front mounts can work well - provided the ducting is good, the airflow through the intercooler is good (this is important, as you want a good rate of airflow through the radiator, and as some have found with meshing in front of the intercooler, it\'s easy to upset the airflow and reduce the effectiveness of follow on components).  There will be some heating effect when the car is stationary - but this can be helped with fans (electric or otherwise).
 
V Mount setups can also work well - again ducting is important.  Heatsoak at idle must be less than with front mount setup, but will still happen.  Turbo pipework can be kept short with potentially less bends and hence lower pressure drops than with a front mount
 
Then top mounts - not an option for the FD guys, but they were standard on the FC.  I know everyone calls them \'interwarmers\' - and they certainly do suffer from massive heatsoak problems in stationary or slow moving traffic - but at speed, with ducting (bit of a theme this ducting) they perform suprising well.  A lot of well paid engineers came up with these designs - so they won\'t be rubbish until you start pushing things beyond stock.
 
I\'ve got real figures from my ARC intercooler replacement verses the stock intercooler - and the improvements are marked - but I would not consider a top mount for drifting or any activity where the car is sat idling for any length of time and then expected to perform as the heatsoak will cost you valuable horsepower.
 
As for pipework lengths, bends and stuff - there is an effect, and I\'ve seen some of the calculations - they are often done assuming static air in the pipes - which is far from the real world.  It has to take some finite time to repressurize the pipework - anyone with a comination boiler with a filling loop can see this for themselves -it\'s exactly the same principle.
 
One other thing that\'s worth considering - protection for the intercooler / radiator from incoming stones and debris - a front mount setup will expose most of the intercooler to oncoming crap - by definition the V mount setup will present less frontal area to oncoming crap, and also because the surfaces are at an angle - they will tend to deflect debris.

[jetpilot]

but surely the amount of air coming in from the opening in the nose is the same, so with a vmount you get 50% or the air at ambient temp to the intercooler, and then 50% of the air to rad at ambient temp to the rad. With a front mount you get 100% or the air to the intercooler at ambient temp and then 100% of the air at an elevated temp to the rad (assuming good ducting for both setups). whilst you want the intercooler to be as cold as possible at all times to maximise charge temp, the radiator has to ensure that the engine doesnt get too hot, so if the elevated air passing over the rad gives sufficent cooling then the higher temp caused by the front mount isnt really an issue. there will be a presure drop across both the rad and the intercooler affecting the cooling air, and in the case of the front mount this will have a greater effect as all the air has to go through both, (similar to resistors in series (front mount) and parrallel (vmount)). If the pressure drop across the intercooler is too great, then it will negatively affect the airflow through to the rad in an FMIC which may well affect engine temps. if this is the case then re-arranging to a vmount will help loads, as it will give more airflow to the rad- bt surely it isnt really a case of \'vmic being better than fmic\' as the root cause is a rubbish IC design?

Why would 100% of the air through the front suddenly divide itself to 50% for the intercooler and 50% to the rad? The volume of air is still the same surely, just now passing through two things rather than one?

[Prof]

Why would 100% of the air through the front suddenly divide itself to 50% for the intercooler and 50% to the rad? The volume of air is still the same surely, just now passing through two things rather than one?

I think Marco\'s referring to the fact that in a vmount the air coming in through the front can only go through either the intercooler or rad - not both, so there will be a division of the air - arbitarily 50% going to each device.

[jetpilot]

I think Marco\'s referring to the fact that in a vmount the air coming in through the front can only go through either the intercooler or rad - not both, so there will be a division of the air - arbitarily 50% going to each device.

Sorry, my tiny brain cant accommodate that! :Giggle

What difference does it make if there are two things in the path of air flow, its still the same airflow, but going through both? Its not dividing but both will get the same force?

P.S Not being obtuse or argumentative, but just cant my head around that!

[marco]

yeah, sorry i should have made it clearer- with a front mount all the air goes through the intercooler and then all goes through the rad, with a vmount some goes through the rad and some goes through the intercooler, but it will be roughly the same total amount of air between the two varients. if anything the vmount will flow slightly more air due to less of a pressure drop, but i couldnt say how much this will affect it. if you have the same amount of cooling air then you have roughly the same cooling capacity. I think...

[Koose]

Well, this has cleared that up  then :flamed

[jetpilot]

Well i had a vmount, but i also guess a lot comes down to budget too! You will need a rad with a v mount, a front mount needs just the intercooler and personally i would say the average user (track work/road) would notice little to compare between the two.

[Nik da Greek]

if anything the vmount will flow slightly more air due to less of a pressure drop,

Sorry to be pedantic, but if there\'s less of a pressure drop, it\'ll flow less air :3Confused Air moves from high pressure to low, so what you want is the air to hit a wall and build up massive pressure against it that then forces itself through the holes in that wall.....rather like the upright face of a front mount, in fact :rolleyes:. What you don\'t want is the pressure wave building up so far back from the initial interruption of the IC face that it starts spilling out through other routes and lessening the pressure against the core. Hence the ducting.

I think for about 98.9% of us it\'s down to fashion, either a decent FMIC or V-mount will be perfectly adequate for all your needs in anything less than outright competition circumstances. Fit the one you like the look of best :Giggle

[L18M]

I think for about 98.9% of us it\'s down to fashion, either a decent FMIC or V-mount will be perfectly adequate for all your needs in anything less than outright competition circumstances. Fit the one you like the look of best :Giggle

that\'s why i chose v-mount :Giggle
looks better imo and also sounds fancier :p

i didnt have much of a plan for the car just fast road car but now, seeing as it drinks so much, highly thinking of making it more of a track toy, just need to add bigger tub then away we go... oh need to add working car 1st lol

[marco]

Sorry to be pedantic, but if there\'s less of a pressure drop, it\'ll flow less air :3Confused Air moves from high pressure to low, so what you want is the air to hit a wall and build up massive pressure against it that then forces itself through the holes in that wall.....rather like the upright face of a front mount, in fact :rolleyes:. What you don\'t want is the pressure wave building up so far back from the initial interruption of the IC face that it starts spilling out through other routes and lessening the pressure against the core. Hence the ducting.

ok. lets take away the rad and intercooler, and instead repalce the them with solid plates. all the air flows through the opening in the bumper, hits the plates and then, goes nowhere. but if you measure the pressure difference between upstream and downstream of the plates, the difference will be big. big pressure difference across the plates= little flow.
now lets take the plates away and replace them with chicken wire. the air comes into the bumper, flows straight through the mesh, and then goes where ever (under the car, out of bonnet vents etc) there will be pretty much no restriction to flow, but measure the pressure upstream and downstream and there would be virtually nothing. small pressure difference across the mesh= good flow. pressure drop basicly gives an value to the amount of restriction.
the restriction is caused by the geometry of the intercooler/ rad, so in the case of a fmic, you have the pressure drop caused by the intercooler + pressure drop caused by the rad (you have to add them together, similar to resistors in series) in a vmic the air can go through either IC or rad (so similar to resistors in parallel) continuing with the electrical stuff, the freestream (jsut ahead of the car) energy/head/staganation pressure is basicly a function of the car speed and equates to voltage and the amount of air flowing through the system is current. V=IR, re arranged gives I (flow through the system)= V (freestream energy) / R (pressure drop across the system). so by reducing the pressure drop you get greater flow through the system for a given amount of freestream energy.

i hope that makes sense, the beer is starting to take effect. :guinness:Hammer

[Prof]

In fact the cooling has less to do with the pressure and more to do with the temperature differential between the incoming cold air and the hot air/water inside the intercooler/ radiator.  The difference allows heat transfer between the 2 - the greater the difference the more transfer occurs.  Keeping the air flowing keeps the differential high and ducts away the warmed air to keep the system performing well.
 
It\'s why blowing on something cools it down much more quickly - it\'s not the fact that your breath is cold - often it isn\'t, but it\'s the fact that your blowing causes a flow and draws in the cold air with it to provide better cooling.

[Nik da Greek]

i hope that makes sense, the beer is starting to take effect. :guinness:Hammer

Nope, sounds suspiciously like boIIocks to me :rollin

[Nik da Greek]

It\'s why blowing on something cools it down much more quickly - it\'s not the fact that your breath is cold - often it isn\'t, but it\'s the fact that your blowing causes a flow and draws in the cold air with it to provide better cooling.

Really? I thought it was because the escaping heat energy from whatever you\'re blowing on has reached a point approaching saturation of its thermal efficiency in the surrounding air (which really isn\'t a good conductor) and your blowing imparts enough energy locally to remove the point of saturation and allow more energy to escape from the object?

[marco]

Nope, sounds suspiciously like boIIocks to me :rollin

if you could point out where i am going wrong then i would be grateful....:p

[AtomicRex]

In fact the cooling has less to do with the pressure and more to do with the temperature differential between the incoming cold air and the hot air/water inside the intercooler/ radiator. The difference allows heat transfer between the 2 - the greater the difference the more transfer occurs. Keeping the air flowing keeps the differential high and ducts away the warmed air to keep the system performing well.
 
It\'s why blowing on something cools it down much more quickly - it\'s not the fact that your breath is cold - often it isn\'t, but it\'s the fact that your blowing causes a flow and draws in the cold air with it to provide better cooling.

It does work...but only on something that emits water.  So when we sweat the wind causes the evaporation.  Likewise we blow the coffee because the molecules that are bouncing up and down at the top of the surface are blown away.
 
Doesnt work on metal though.  But would do if you used an intercooler spray