Larger pressure drop -> less flow!

 

larger volume=larger pressure drop=larger flow

 

i just finish installing the 997.2 ic on my 997.1tt (reflashed+sport exhaust 200cells) i did it in 4hours.before i saw 70degrees celcius at the end of the 3rd gear but now only 45 degrees celcius,i feelthe car faster.on the stock ic my best 60-130mph was 8.9s,i will try new 60-130 and let you know the new numbers

 

Hey Marek,
I am looking at ordering the pressure testing rig you have on your website. I am assuming with that and a compressor I can do the pressure test. Have you though about putting together a simple DIY video showing the steps to do the pressure test for someone who has not done it before? Even something filmed with an Iphone and put on YouTube showing you using your pressure rig would help someone who hasn't done it before and probably get you a few sales in the process.

Thx.....

 

+100! I have been contemplating your rig as well, but am intimidated by the process! Therefore, I'm afraid it would just sit on a shelf in my garage. Pleeeeeeze Markski, pleeease!

 

you will re-invent physics

here is a retest with heat soaked beginning and much warmer as before, also air densitiy was much less (make my turbos spin higher).

 

You're getting confused. The .2 cores have a more restricted flow based on Champion's testing. Because it has a denser core, it is a better heat exchanger. This principle has NOTHING to do with the GT2 expansion intake that you suggested below.

 

first your graph shows that 997.2 ic are efficient...over 200km/h iat is 50 celciuswich is lower than 997.1 ic(70 celcius).
Second i am not re inventing physics

http://www.geagolf.com/GEA%20Pressure%20and%20Flow.html

the link above is the proof that when you have a higher flow rate, you have a higher pressure drop due to increased friction losses.
In order to have a higher flow rate with a constant velocity, we have to increase flow area, according to the following equation:

Qdot = Area*Velocity, where Qdot is volumetric flow rate.

Thus by increasing the flow area (cross sectional area) of a certain conduit having a constant length we are increasing the conduit volume, hence we can say that by increasing flow area, we increase volume, we increase flow rate, we increase friction losses which finally leads to concluding that we have a pressure drop.

 

Hi,

I am not too focused on having a bigger pressure drop with the 997.2 coolers. Any turbo like a k24/18g can easily produce a bit more flow to compensate - as most of us users will not be operating at the flow limit / outside the efficiency map of the compressor. I think our tunes for this engine are generally by far and away limited by avoiding knock (i.e IAT, relatively low octane content and relatively high compression in the engine), not the CFM flow rates of the turbos.

Also worth bearing in mind is the first law of thermodynamics, i.e PV=nRT, so as we cool the air in the cooler (T) and as volume (V) is constant as is the constant (n), then pressure (P) must drop in line with the air temperature. So what I am saying is "expect a bigger pressure drop if you cool the air more"... In terms of friction of the air with the surface area inside the coolers, I think the Champion tests, probably adiatic in nature, showed like for like on a flow basis the .2 cooler is slightly more "restrictive" - which will also cause some friction related pressure drop. I dont know the ratio of the total pressure drop attributable to the drop in T and that due to surface friction, but suspect the air temp drop is predominant if you look at PV=nRT. As volume is bigger in the .2 cooler, velocity of air (for the same mass flow rate of air) will be lower through the .2 cooler - which should compensate a bit for the added friction as the air passes through. So i dont have test data to back up what i am saying, but the equations suggest the friction related pressure drop is not a material factor here.

Also, the temp drop of the hot air is proportional to the size of the deltaT (difference between boost air temp and ambient air passing thru cooler). The deltaT is highest at the inlet to the cooler, so the boosted air drops its temperature most as it starts its journey through the coolers and is already slower in velocity right then. Also I think a black plastic end tank at the inlet will be cooler than a metal one (thanks to Planks work we know black plastic rejects more heat than shiny metal, a bit like your black tinted windows) although empirical testing would ultimately be needed to confim if correct. So black chrome end tanks would really get my vote - especially as they would also presumably stay on !

 

I find it odd that many discount bar n plate ICs yet these same ICs carry upwards of 1000+whp P cars... I am the only one seeing this ?
IAT data does not show engine efficiency performance (LOAD) so everybody just assumes the engine must be performing better.* Someone needs to measure LOAD because that is the TRUTH.* It’s hard to do controlled testing since ambient conditions will vary.**For best IC cooling, you want cool MOIST air because that will transfer heat the best.* For engine performance, you want cool DRY air because that contains a higher amount of oxygen molecules to burn.*To do truly accurate testing, same environmental conditions are a must otherwise all this is just playing with numbers...
I'm not discounting the ICs and probably they will neck to neck at 1.2 bar or close with good bar n plate...
but to say they are God's gift to the P car owner for under $1000 is miracle to say the least...

just my .02 cents
markski

 

I dont think people are discounting b&p coolers per se, its just a core manufacturing method. Secan & Marston coolers are bar & plate cores and these do well on P-cars that make 1000+hp and sustain those levels for more minutes on end (in 3.5" thickness, no less). Garret and others make decent B&P coolers as well.

IATs are certainly not the end-all be-all, but when dudes like George run 1.5 bar on a 68mm VTG built motor 997 and turn 100-300kph several seconds faster w/$900 ICs vs 3x$3500 ICs (he went through several different brands) in identical conditions, some eyebrows are going to get raised and some spears thrown. The times (or Pbox longitudinal accel data) would indicate that the engine is producing more power -now couple that with the addition of the lower IATs.

Quite frankly, I think the bar & plate distrust comes from the relatively weak cooling performance from some of the lower density core designs. I don't like "Corky" coolers on these cars because they don't cool all that well, yet many cooler manufactures use these things in droves presumably because they make every size core under the sun so making them fit is much easier and cheaper than having a one-off Porsche optimized core produced. The down side is that the "one size fits all" core isnt optimized for our relatively short 14" core length in any way -their 14x9" core uses the exact same loose fin packing as their 36x24" core (or any other of their cores), 'splain that!

In other news, the UK bros have been testing these on Bruntingthorpe on their K1639 package at 1.5 bar and showed quicker acceleration and cooler temps through 200mph.

Guess which coolers these replaced?

I can't tell you the # of PMs I get from dudes (particularly road racers who run flat out for long periods of time) saying things like "I switched from brand X and my car is so much more consistent", etc, etc. For the money they spent previously on crappy coolers, it is a miracle to them.

Now if only someone would weld end tanks onto these...

 

Earl, as usual, great post. I've also wondered about the quoted excerpt above. If one were to tackle such an endeavour, it might make an excellent, durable $1,300-1,400 IC, no?

I'm surprised it hasn't been attempted yet.

 

But the same ICs they tested in greece made 867rwhp and 850( kept low stock motor) on our 997 with room to spare at 1.7 bar... and over 1000whp on 996s... so something does not add up... when someone said that bar n plate performed worse then stock... thats just absurd... what probably did happen was the install was wrong.. you have to use the lower duct and turn the upper part into a cavity... plugging some holes up etc... I made that mistake on our 997 2 years ago and learned the hard way.... I mean dynos do not lie.. I can't speak for the 997.2s but I do know that the 4.5s bells do well on high HP cars... I have dynos, a 9 second run, and mid 4s to prove it...
not discounting anything just raising some eyebrows as well..
markski

 

the link you mentioned only proof that you are not alone with your false assumption

you cannot regard to only the higher volume inside the core and forget the piping after it. 996ttbandit discribed it very well!

btw: Qdot=change rate of volumetric flow rate
and Gasdynamics is a very very complex science, as we handle with either compressible fluids, friction AND heat exchange which does make things not easiert.

 

At last i could give some,although modest, feedback of these IC's. Over here you really can't do real pulls on public roads so now the result of 80-120 kph @ 3rd gear.

OAT +25C
IAT at start +28C
IAT at end +26C
Boost 1.3 bar

Time spent 2 sec. Boost 0.1 bar to 1.3 bar in 1 sec.

I'm waiting to get the car to a track for definitive answers.