can an intercooler be too big?

assuming no drop in pressure from entry to exit on the i/c itself, can fitting a larger i/c reduce boost and therefore power?

I am planning on fitting a longer narrower i/c (think sierra cosworth proportions) rather than the big square/rectangular one half of which will be covered by the bumper.
Its an A4 (sorry i know its the wrong forum but my mk2 8v doesn't have a turbo!) and I have bought an S4 bumper as it has a huge wide air dam under the centre of the bumper.
I specced out a 700longx200highx86mm deep core.
It fills the space behind the air dam perfectly.
How do I work out if this is going to be big enough or too big for the engine.
Its currently 180bhp, but I am getting this i/c for an IHI and circa 330bhp.

Any ideas?

 

you might see a bit of lag, due to the volume of the larger intercooler, but your counteracting this well by using an IHI turbo. shouldnt get any more lag than standard. as long as its for good airflow to it, the size you described should be fine for 300bhp+.

 

A turbo needs to fill up the intercooler with boost before the boost can enter the engine, the smaller the turbo the longer it will take to fill a large intercooler. An intercooler too big for a turbo will result in turbo lag.

The specs of your intercooler are okay, there's peops out there with much larger intercoolers on KKK turbo's. An IHI should would fill an intercooler of that size with eaze.

 

nice, that what i want to hear.
bring on the IHI!

 

Think there was a big thread on here about this

 

You mean the one where a certain person was insistent his intercooler could defy the laws of physics? (incidentally the same person with interesting views on high pressure fuel safety)
Edited by: martyn_16v

 

search function is fuxed at the moment, anyone know where this thread is?

 

is there a way to calculate minimum intercooler size and flow for a given turbo/bhp?

 

LOL

 

ask trendy tramp but dont expect a simple formula

 

Running the system without a dump valve can counteract some of the negative effects of using a large intercooler. I.e. you don't suffer from the repressurisation 'lag' after a gear change. A standard turbo & pipework may not be suitable to run in this configuration however.

 

don't ask me, i'm retired

to a nice tartan box in a quite suburb. can give you the formula for a nice cuppa if you want? (will cost you 30p though )

tt

 

I must admit I didn't post this at the time but if you include the effect of *moist* air (which ofcourse atmospheric air is) passing through a cooler then you can have things getting colder than the ambient air temperature due to the cooling effect of condensation and evaporation of water in the air...


So defying the laws of physics isn't actually needed to produce the effect Bill was claiming he observed.


Dunno how that thread ended actually I seem to remember getting bored halfway through it - amusing though

 

one of mine


this one....


kinda skirts round the topic some what

 

For some reason having all the 'p's highlighted in that thread makes me read it in my head in the voice of Daffy Duck

 

look at the whole install, no sharp bends immediately before or after the turbo. Pretty sure TT tells us some good guidelines on that old thread

 

From the numerous articles I have now read I get the feeling i am no further ahead.

One thing I don't understand is...People keep referring to pressure drop across inlet and outlet pipes of the intercooler. I thought the whole idea was that the internal spaces of the cross section of an intercooler were meant to be as close to the inlet and outlet pipe so that flow remained as close to the same pressure across the system. I appreciate that this takes zero drag into account, but do i/c come with a rating that says if they have been flow tested and if they have a p/d at a certain flow, and/or if this flow is applicable to a particular turbo application?

When it says "good for 300bhp" is that just a made up figure?

 

when i see IC's with those claims, ask them for the test data, airflow, pressure's etc before & after... and when they cant/wont, you will know.

OR..

try one for yourself.. take a look at some race cars, fast road cars which are proven and use their designs as a guide, and or ask them where they got there's made & designed etc.

I had a couple of iterations of mine before I was happy with its performance.
Edited by: badger-bill

 

I have been told to match the turbo to the engine through compressor maps, I am pretty happy with the turbo choice as it has been done a number of times.
I have ordered a VF34 IHI with a set of 565cc injectors and a uprated fuel pump.
I have an S4 bumper for the front that has three massive air dams running below the actual bumper line
like so: here.
As this is a longitudinal engine and the turbo is on the left (looking into engine bay from front) and the inlet manifold is on the right, I had planned as short a pipe as I can get away with between turbo and intercooler (approx 15") and intercooler and inlet manifold (approx 12").

The intercooler would run the bulk of the distance between the line of the turbo on the left and the line of the inlet on the right. Hopefully filling the air dams in the front bumper but not bigger.

Would an intercooler of these dimensions be effective?
The old sierra cosworth i/c are the only ones I have seen that are wider and narrower.
I don't see the point in covering half the height of the i/c with the bumper/bumper shell.

In my A-level physics mind, the more i/c that is in the air flow and the longer the inlet charge is in the intercooler the more effective it has to be.
Also wider, deeper and shorter (height) design must allow a greater flow without the significant pressure drop, compared to the charge going from a 3" pipe into an i/c that is 12" high and 2" or 3" deep.....no?

Does this make sense? I understand the principles but am going down a route that I can not find ever being done (custom IHI on a longitudinal 1.8t engine)

 

urgh, now you're getting into thermophysics, which is a total pita to figure out, lol.



Turbulance is needed to make the heat pass from the intake charge itno
the IC, and then on to the air flowing through the IC, but to get
turbulance you need speed, so the air has to pass through the IC
quickly enough to pass it's heat to the intercooler effectively, but
slowley enough to stay in the intercooler to do it's job properly, it's
kind of a balancing act.



As for what would be best for your car? i have no idea, i've just fried my head trying to explain the above, lol.