CFM - BHP and intercooler sizing.

[Evodelta]

Yes, that is a good diagram Acki and shows how important a good tapered duct is, especially if your intercooler core is a bit on the thick side (lets say over 65mm) the cooling air must be forced to go through the core otherwise it will simply try to go around it, the Grp A integrales had a perfect example of this under the bonnet (see below), notice also the beautifully shaped end tanks to aid the internal flow of air, it's a work of art.
I'm afraid I have no pictures I can post up here that will not break the rules as they are of other peoples attempts, ranging from what to do, to what not to do, but I'm sure if you have some specific application/design criterior/problems in mind then it could be discussed here.

Martin.

[Acki]

yes! That's it.

Last night I have tried to calc a flow map.
On the garrett homepage you have some hints for this. :)

The cfm of a charger is the power you can use.
I think it's a other type of efficency you have normally on a cooler.
Important for a good cooler is the pressure loss.
I have found some with 0.2psi pressure loss, this sounds very good!

But in the end, don't make the cooler too big and not too small. I think to think too much about this "costs" more than make 0,2bar more pressure to have the same power...
I mean a cheaper cooler with good parametres is ok for normal use than to buy a expensive totally perfect cooler.

[Evodelta]

As with most things (not all) on an engine it's a question of compromise.

You quote ".2 psi pressure loss" this seems very low to me, but you haven't quoted at what Cfm or boost pressure this figure was obtained at, if someone has managed to get this figure by blowing through the core with a cheap hairdryer then fair enough. ;-)

Also, a very low pressure loss cooler will not have much in the way of heat rejection, afterall, if you send your air through a 50mm diameter pipe you will suffer no pressure loss, it won't cool the the air though either, you have to slow the air to get it to cool.
The air is cooled by 'turbulators', fins in the tubes which pick off the heat, a core with short tubes will need to be dense with many fins, a longer tube core will need to be less dense with less fins or turbulators within its tubes.

Do you mean the turbobygarrett site? There is also a good Bhp-per-cooler-size chart in there too, of course, it is for their cooler cores, but once you have got your head around the strange way in which they list the sizes (Hot flow, no flow, cold flow??) you can compare this against what size you may have come up with for a cooler to see whether you are 'ball park'* or way off the mark.

Martin.



* Sorry for my English language phrases, I hope you understand: Ball park = in the region of.

[Acki]

Yur right 0.2psi at which flow speed but you can also buy a intercooler where you don't know any pressure loss ;)
I think you must "see" that this is a good intercooler or not...

In the german uno forum many guys used the bmw 525tds intercooler.
Nice intercooler, no question. But whit stock intercooler you had 1,0bar in the manifold. After installing the bmw 525tds intercooler you had only 0,8bar!
This is 0,2bar more pressure loss and the standard uno intercooler is not very good!

Install a gauge in the pipe from charger to intercooler and a gauge in the manifold, then you know the pressure loss. You can also use the small "pipe" from charger to the wastegate with a T.
Clear what I mean?!

[Evodelta]

Yes, I know how to measure pressure loss. ;-) I am going to have to do it this way too, but using 2 digital guages which measure to .0 of psi and a camera (either still shots or movie) fixed in the car to capture what is happening. This is only any good if you are prepared to go through a pile of coolers to find one that works, better to design or buy one that does the job properly in the first place.

Using the BMW cooler seems like maybe they have traded flow for better cooling. (you would hope so!) from what I have seen of this of this Bmw unit it has no place on a performance car, it was designed by a man on a budget with a tape measure, is too small in section and far too long, it is for a low powered diesel car and should have been left there too.
Do you have any pics of this set up? It is impossible to discuss it further without having any pictures, measurements or specification.
What BHP are you going to run with your cooler?
Have you seen the Dutch DIY intercooler site?

Send me your email address, I have some things which will be of use to you (but of no use in this thread).

[jmcpower]

Hi Guy ,
A Very interesting conversation that i would like to add a question into this already complicated subject !
Lets take a very simple example the 34mm Turbo Compressor Restrictor on a Rally Groub A car turbo motor 2.0l !Its supposed to be there to limit the max Power of these engines to aproximately 300hp regardless the amount of boost !
Last week i have flown tested one 34mm Turbo restrictor and got 216.8 cfm corrected @10" depression.
I would like to ask how this restricted flow of 216.8cfm translates into a Power figure of aprox. 300Hp ?
And if a standard head with a 135cfm @10" inlet port flow would benefit from improoving it lets say to 150 cfm @10"!

Mike

Last week quote]

[Acki]

I drive on the highway in the 3. or 4. gear and can look what the gauge say ;)
I can also use a data logging with a laptop. But there I'm searching for a simple programm to get the data's in the laptop :(

My mail adress is Martin.Ackermann@fh-zwickau.de

I have the Maximum Boost Book now.
I will read it in the next weeks, on the first look it seems to be a good book. (I think this sentence was bad englisch... *ggg*)

For the 525tds intercooler, here some pictures: http://www.tueren-shop.com/wbboard/thre ... boardid=17