Paul Bloomberg

I also had someone open the restricted side of a IC. I'm not sure if it made a differance or not, but I could sleep easier : )Then I thought about the heat transfer???
Put it this way I posted a ad on the rennlist for a short time to sell try to them and when someone asked if it made a $300 differance. I had to say no it didn't to me. But a cert. alum welder could re-fab the restricted end for $75 or so. Plus what Danno say's makes since.
Paul

turbo944

Also, does not the restriction to flow help in a little lower numbers on the temps? If the restriction is causing the air to be compressed as it goes into the intercooler, that has the capability to increase the temp a little more before it goes in. Again as Danno says, more efficient airflow, not a better cooling apparatus. The temp numbers on their Lindsey's site actually show higher temps with the Stage II intercooler than on the stage I on exit of the air...showing exactly the information being described. Faster flow with the same transfer space = less cooling of the air. The Stage II shows 20 degree higher exit air than the the Stage I does, and this is probably due to the higher CFMs going through at an increased rate with less contact time to transfer off the heat of the air going through the intercooler.

yoyoguy2

i think the thing is air doesn't necessarily flow in greater quantities through the intercooler. look at it this way: your car has the same air going through the intake path at a given rpm/boost/load level. every time. it's measured by the afm, if it wasn't then you couldn't make an ecu that would keep the car running right. what lower pressure drop means is that it takes less effort to get that air through the intercooler.

it's the same amount of air, but it's easier to get, so power is not wasted sucking it in on the intake stroke of your engine. so therefore, if you compare two intercoolers of a given size, but with different restriction levels, they will flow the same amount of air at any time (perhaps adjusted for higher boost with lower restriction), so with the same air flowing through the same space, it should cool the same, but still provide a benefit from less restriction.

that's what makes sense to me anyway....

JustinL

Has anyone run a comparison between this and the SFR intercooler package? There is a big price difference, but is the performance increase worth it? Also does mounting the intercooler in front of the radiator cause increased coolant temperatures? Reduced airflow past the rad and now this air is heated.

Justin

Danno

I don't have the numbers, but on a qualitative analysis, the SFR intercooler should provide a significant boost in performance over the stock or Lindsey units. Temperature drops would be dramatically improved.

While the coolant temperatures won't be as low as stock, the 951 already has quite a good cooling system.

white 944 turbo

Danno,
You do mean over both the Lindsey stage 1 and 2 intercoolers right? I think that the Lindsey design is a happy medium for performance and fit but the bottom line is a 15+ year old design/tech. being enlarged or modified doesnt seem to be the best solution when it comes to performance when you have so many other intercoolers out there.

Sean Hall

Dan,
If you increase the volume of air through the heatsink(intercooler), more heat will be transferred to the heatsink. Therefore, you cannot cancel everthing out because dT is different between the two equations.
So, if you have a situation where the delta between outside air and inside air(intercooler temp) increases, the cooler will extract more energy. Make sense?

-Sean

Danno

"If you increase the volume of air through the heatsink, more heat will be transferred to the heatsink. Therefore, you cannot cancel everthing out because dT is different between the two equations.

So, if you have a situation where the delta between outside air and inside air increases, the cooler will extract more energy. Make sense?"

But I'm keeping the dT between the outside & inside the same in both cases to remove as many variables as possible. In my example, I was keeping the outside factors all the same. The same ambient air temperature flowing through the intercooler. The same outside air velocity and volume.

My assertion is: increasing velocity of the same volume of air through the intercooler will result in lower temperature drops

Given:</font><ol type="1">[*]<font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">identical outside atmospheric conditions, same ambient temperatures, same air-flow volume and velocity through intercooler.</font></li>[*]<font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">and identical internal intercooler conditions, that is the same turbo-outlet/intercooler-in temperatures</font></li>[/list=a]<font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">With the only difference being the velocity of the
inside air flowing through the intercooler (for the same volume, both inside & outside temps the same; same dT), then the higher-velocity charge will be cooled less.

I THINK THIS IS WHAT YOU'RE TALKING ABOUT HERE:

Now here's fine distinction I didn't bring up the last sime. Since the upgraded intercooler has less restriction, at the same boost-level it will flow a higher volume of air through the intercooler at a higher velocity. If dT were the same as before (same outside ambient air temps and same turbo-outlet/intercooler in temps), then the same amount of heat (joules, BTU etc.) will be extraced per second. However that heat is spread out amongst a larger volume of air in the free-flowing intercooler. Thus any single piece of air (think FEA here), will have less heat extracted.

So yes, if you flow more CFM through the intercooler, you can extract more total heat. But the amount of heat removed per cubic-foot will be less than before, therefore, the degrees dropped per cubic foot is less. This is kinda like comparing HP & TQ, you have to add an integration step involving time as well.

"So, if you have a situation where the delta between outside air and inside air increases, the cooler will extract more energy. Make sense?"

We've talking about two different starting conditions. I'm standardizing on the same delta-t (inside & outside temps) so that we can isolate the effects of increasing velocity through inside of the intercooler only. <img border="0" alt="[bigbye]" title="" src="graemlins/xyxwave.gif" />

Just think of a more common-sense analogy; stick your hands on a hot 400C stove. Same delta-t because your left hand is at 37C and your right hand is also at 37C. Put them both on the same stove burner with the left one on for 1-second and the right hand on at 2-seconds. The hand that is in contact with the stove-burner for the longer time transfers more heat for the same delta-t right?

Sean Hall

Danno,
You originally said:
</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by Danno:
...If you flow something through the intercooler faster, it won't cool as much... you have to increase the surface area.
[/QB]</font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Danno, this is incorrect.

That is why I posted:
If you increase flow, delta t increases too.
...And then went on to say, If you increase the volume of air through the heatsink(intercooler), more heat will be transferred to the heatsink. (ie..more effecient intercooler)

Also, take a look at this page:
<a href="http://www.gnttype.org/techarea/turbo/intercooler.html" target="_blank">http://www.gnttype.org/techarea/turbo/intercooler.html</a>

In particular:
"Heat transfer goes really well when there is a large temperature difference, or driving force, between the two fluids. This is shown in equation 1 as a large DTlm. It doesn't go as well when there is a small temperature difference between the two fluids (small DTlm). The closer you get the intercooler outlet temperature to the outside air temperature the smaller DTlm gets, which makes the heat transfer tougher." &lt;--- this is the point I'm making that contradicts your orignal post.

Cheers!

-Sean

Danno

You're still not incorporating the time factor into how an intercooler works. That Regal site also takes a simplistic view of heat-transfer as well by not analyzing a fixed volume, its velocity and time spent in flowing through the intercooler (air-column doesn't sit stagnant in the intercooler while a mean/average amount of total heat is removed).

We're still talking about two difference scenarios here. I'm talking about how moving the same volume of air through the intercooler faster will remove less heat from it (less contact time). Whereas you're talking about moving more volume of air through the intercooler faster. In the same amount of time, yes this will remove more total heat from the larger volume flowed.

I'll explain the difference about the situations we're discussing, and how we're both right in describing two different things. Then I'll get into the nitty gritty of explaing how both delta-T between the inside & outside of the intercooler should really be used along with the TIME factor (more important than delta-T).

First some assumptions:</font><ol type="1">[*]<font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">constant outside ambient temperatures</font></li>[*]<font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">constant flow such that intercooler core is always at same temperature as ambient air (zero heat-soak)</font></li>[/list=a]<font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">"The closer you get the intercooler outlet temperature to the outside air temperature the smaller DTlm gets, which makes the heat transfer tougher." &lt;--- this is the point I'm making that contradicts your orignal post. "

This is always true regardless of the velocity through the intercooler. This is also why it's better to have a wide and short intercooler path, rather than a narrow, long one (more on this later).

Then you have to incorporate the time factor in with the change in Dt through the intercooler to calculate total heat extracted (joules) for identical volumes of air that has traveled through two identical intercoolers at different speeds.

However, in order to calculate total heat removed, we would have to integrate across the intercooler with DeltaT-in to DeltaT-out to account for the drop in intake-air charge as it travels. Then do another integration with respect across Time1 to Time2 in order to equalize the velocity differences to determine total heat removed for the identical volume of air. However, I'm going to make it easier with an FEA-style analysis using an infinitesimally small cross-section of the air-column and what happens to it at fixed time-slices as it goes through the intercooler.

First, here's what Sean's talking about, moving air thorugh the intercooler quickly will remove more heat. Implicit in his correct claim of more heat removed, is a larger volume of air. However, each individual piece of air (be it a CC, a cubic-inch, or a cubic-foot), will have less heat removed at a lesser temperature drop. Here's why:

<img src="http://www.gururacing.net/ImagesMisc/Intercooler-FastFlow.jpg" alt=" - " />

Let's say it takes three time-slices to get through the intercooler. As the intake-charge flows through the intercooler, the temperature difference (delta-T) between the inside & outside is reduced, the total heat transferred is less and the temperature drop for the same piece of air is reduced.

Here's what happens when you slow down the flow (by 33%) through the same intercooler to give it more time to transfer the heat off:

<img src="http://www.gururacing.net/ImagesMisc/Intercooler-SlowFlow.jpg" alt=" - " />

Since we have the same delta-T gradients at time-slices T=1,2,3 the same temperature drops occur as before. However, now we have an extra time-slice T=4 for extra heat transfer. And yes, since the intake-charge has cooled and delta-T is lowered, the transfer is very inefficient here, but only at this last stage. However, this final minimal temp-drop is cummulative on top of previous ones and the final result is that the slower flowing intercooler gives a cooler outlet-air charge even though its average efficiency is lower. Notice the results closely models the differences between the Lindsey-II (fast) and Linksey-I (slow) intercoolers. Perhaps they only have a 20-25% flow-velocity difference instead of the 33% I used in this example.

We can take that one step further and reduce air-charge velocities even more by making the intercooler even bigger (like the <a href="http://www.speedforceracing.com" target="_blank">SFR intercooler</a>):

<img src="http://www.gururacing.net/ImagesMisc/Intercooler-LargeSlow.jpg" alt=" - " />

Even though air-velocities at the inlet and outlet may be the same, the expansion at the end-tanks slows down and speeds up the gas column. If we have an intercooler that's twice the volume as stock, the gas velocities inside will be 1/2 as fast and the time to transfer heat will double (for same engien displacement and CFM flowed out of turbo).

As you can see, the very final section is very, very inefficient compared to the initial cooling. But giving it that extra bit of time can reduce intake-air temps closer to ambient temperatures. So it takes an intercooler of roughly 100% larger volume to cool the air just 30% more.

PorscheLars

"So it takes an intercooler of roughly 100% larger volume to cool the air just 30% more. "

Have anybody "black anodized" and water sprayed the IC? It should give nearly the same results only with the water spray !?

Due to the fast and slow flowing inter coolers for the Lindsay I and II.. So what Lindsay only do is reducing restriction and that gives less increased temp on the inlet of the ic, and therefore cooler outlet. Restriction itself generate energy.. But no need to say this because its already said.. And if i did not understand this.. you don't have to use more time explaining.. in Norway we have 210% more cooling efficiency due to the cold wether :-)

TurboTim

Sh*t Danno that was an impressive and informative tech note! I guess that is why our intercooler was dynoed to make a peak of 14 horsepower at the wheels;^) It also made a noticable difference in power across the board. BTW, The SFR intercooler set-up is only $1095 now. We need to update the website.

<a href="http://boards.rennlist.com/upload/spearcoint001.jpg" target="_blank">http://boards.rennlist.com/upload/spearcoint001.jpg</a>

<a href="http://www.speedforceracing.com/dyno/intercoolerdyno1.jpg" target="_blank">http://www.speedforceracing.com/dyno/intercoolerdyno1.jpg</a>

Russ Murphy

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Have anybody "black anodized" and water sprayed the IC? It should give nearly the same results only with the water spray !? </font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">I haven't yet taken the plunge, but the CO2 IC sprayer triggered by either the TPS or the rpm switch on my SDS looks pretty effective. Here's a thread about it with a link to the product. <a href="http://forums.rennlist.com/cgi-bin/rennforums/ultimatebb.cgi?ubb=get_topic;f=18;t=003105" target="_blank">Cryogenic cooler</a>

Danno

"Have anybody "black anodized" and water sprayed the IC?"

Black-body radiation? Hmmm... interesting....

Outlaw952

I think what is probably happening is that since there is less restriction (and therefore less pressure loss), that the air going IN to the intercooler is colder now, since the turbo has put less work into compressing the air and pushing it down the intake tract. You're basically increasing the efficiency of the turbo/intercooler system, so you should expect the intercooler outlet air temps to fall.