If you just compare cooling surface area of stock intercooler vs aftermarket options;

The stock intercooler surface area its made up of 10 sections measuring 17" x 5" = 850 sq ins

I have large aftermarket FMIC that will need a lot of mods to fit, it measures (core) 18" x 3" x 11", giving 18" x 3" x 15 (plates) = 810 sq ins cooling surface

Before I start cutting and fitting this new beasty in, I am starting to question why.

What am I missing here, the stock intercooler seems to have massive surface area, if you could make the flow more efficient, isnt this a better option than dropping in a big aftermarket FMIC and chopping the front bar or grill etc?

thanks
mike

 

hey i back you up there Mike and say unless it a 3.5 " core its basicly not worth changing in fact after crunching the numbers i found some retailers kit was infact a smaller core with slightly more frontal area with bit with less internal cross section so one could infact being going backwards in comparisoin to a modded tank standard set up .
hey i have a good modded tank one here that I'm not using at the moment Mike i could send it up to play with if you like mate .
Oh somwhere .. havn't seen it in a while ..

 

Adam even at 3.5" (using a intercooler size of 24x3.5x11) its only a 10% increase in surface area....is it worth the hassle..

 

hmm my numbers are differnt mate
i have the standard core being 17long 5" high 5" deep
17x5x5 so 425 cubic inch and a cross section of lets say 25 sq in it is less as the outer cores are just non flowing plates but never mind .
ok my ebay inter cooler is 18long 12 high 3.3 deep
so thats 713 cubic inces of core
and 12by 3.3 almost 40 square inches of cross section for flow of charge air ...
so if ir realy should show a little less pressure drop across at high flow numbers
so to me your looking at 25sq in cross section versus 33 also the nastry wedghe shaped tank on the standard cooler has kind of porven not so ace if you believe the max perforance and lihndsey data ..
and makes sense when you look at it

 

maybe I am wrong but I was looking at cooling area not the volume of the core, so you need to look at how many plates are in the core not the volume of the core, that is why I was using the core count.

 

oops plate count

 

there are several factors
total volume relates to thermal mass so this will detirmine how much you can punish the car continuusly befor you heat soak the cooler .

frontal area how much core faces the wind .. we go for bigger ones but then we all cut up the front of the car to make them work the hope is more frontal will result in more heat shed per second ..

cross sectional area and charge flow .. the area the charge flows thorough this is basicly getting .7 of a psi for free on some cars perhaps .4 psi on a 951
this is kind of the inter cooller choking the charge air .

Julian Edgar got some real good data on intercoolers revealing that truth is in a street application more heat is transfered into off boost charge air than the air from the front of the car . wich makes sense as most of the time there is far more CFM on the inside than the outside across the cores until you get into forth gear
He found under bonnet coolers full of water or even parifin wax were better for street set ups than fron mounts if one was to consider installtion hassle .

i did data log air temps with the standard cooler years ago when i did my bonnet vent
i ripped around the streets with ful throttle and relitivly slow ground speed so only half way through third
the most i could push the ait temps upto was about 30C witch is out standing in real terms
boost was set at about 22 psi a would have seen about 19 due to lack of load

 

my only reference is using the stcok intercooler I saw very fast inlet temp rises under a few seconds of boost (22c - 30c), am I better off going to a front mount 24x11x3 FMIC or a modified flow stock intercooler, keeping mind I'm using a 3.0 16v pushing 17psi boost...

 

Mike i have one with the tank all fattened up and the thout ported throw that in and see what you think of it ..
30c is still very cool mate its probaly 70 or 80 on the way in

 

I personally think a relief vent (ala 968 Turbo RS) would be the single most effective intercooler mod you could make. From a fluid analysis perspective, the popular mod of whacking the end tanks off and replacing them with bigger ends to relieve the perceived "constriction" in the stock unit is, imo, a complete fallacy and I expect that under a true analysis, it will hurt performance of the stock intercooler, rather than help it. The reduction in area at the bottom serves to increase velocity, which helps to acheive uniform flow through the entire intercooler. Seriously, do folks think the Porsche engineers came up with that design without reason? It was a lot more expensive to make the intercooler with the end tanks designed that way and I am sure they had access to much more sophisticated flow equipment than any independent tuner shop has. Thats not a jab at anyone offering to mod the tanks, but certain rules of physics aren't going to be broken.

Regards,

 

on a 250hp car it may be an excelent disighn for that kind of cfm .
but on a 400hp car there is no way there nasty sharp bend is a good thing
it looks to me like there was somthing there at some stage in protyping that is gone but the concave tank remained as it just wasn't worthchanging on a porduction car . the flow data figures on the tank mod seem pretty realistic to me

 

For sure! Way to costly for the ROI.

If you really want to increase your charge air cooling capicity fo with meth/water injection. Much cheaper and WAY more benfits in cooling.

 

I'd argue that. Flow and fluid dynamics aren't going to change drastically between 250 and 400hp on an intercooler. Cutting out that "nasty sharp bend" as you call it will cause the air velocity to slow down drastically, causing a "blockage" through the lower part of the intercooler. That taper should enhance laminar flow, increasing the area of the tank is the last thing you want to do. This is all basic Bernoulli stuff. I'll stand corrected if someone wants to post standalone test data that isolates the intercooler, but I have yet to see anyone substantiate a claim that modifying the end tanks provides any performance advantage. It just plain *can't*, from a basic principals of fluid and thermodynamics standpoint.

Increasing the surface area of the intercooler and airflow across the intercooler (not inside it) would have a greater impact, imo.

Regards,

 

interesting read on the subject... not sure he is on the mark, or that his result corellate well to the 951 IC..but interesting read none the less..

http://www.dvdtfab.com/intercoolertestlab.pdf

 

That correlates *exactly* to the 951 intercooler. I'd question the accuracy of some of the measrements (it was obviously not a lab environment nor equipment), but I'm sure he came to the right conclusion. What he may give up in accuracy he gains in consistency, as both intercoolers are tested using the same methodology and are subject to the same conditions.

I've said this probably 100 times over the years on Rennlist, that end cap mod can't work due to the nature of physics.