JRSC Intercooler Project

[-TJ]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by 99SIVTEC:
The dimensions from eaton's site are 4.90 inches by 4.90 inches for the blower outlet. The core will be the same size as the outlet.<HR></BLOCKQUOTE>

That may be the dimensions of the outlet flange, but the actual charge air outlet is V shaped and much smaller than 24.01 square inches (4.90" * 4.90"). I think the IC will require a lot of testing before you settle on an exact configuration. Maybe over the winter you should build a simple blower test bench to make IC changes easier - run the blower with a variable speed 8000rpm electric motor fitted with your crank pulley.

My guess is that any tubes directly above the outlet are going to see a lot more heat than tubes closer to the mounting flange.

I'm also a little unsure of your blower speed estimates...somebody check my math:

I read someone's estimate of the Si crank pulley at 5.5" and the JRSC Si blower pulley at 4" on the ClubSi thread, so I'll use those in my example:

First you have to find the circumferance of both pulleys:

5.5*pi=17.287...
4*pi=12.566...

Then, divide 17.287... by 12.566... and get 1.375...

1.375... is the number of revolutions that the blower pulley makes everytime the crank pulley goes around 1 time - ratio = 1.375:1

So, at 8000 crank RPM, multiply by 1.375... to get blower RPM = 11,005.

Now, the question is, what is your crank pulley diameter and what is your blower pulley diameter. You can measure at the "root" of the pulley groove, or the top of it. It doesn't matter as long as you measure the both pulleys the same, we're getting a ratio here....

Once you get those numbers, you can find your blower speed. I think you'll find it's a lot faster than 8800 RPM.

Another thing I don't agree with in the ClubSi thread is the mention of the alternator pulley size being a factor of blower RPM. It's not. In a one belt system, the alternator pulley is just along for the ride, same as (but seperate from) the blower pulley. Remember, the CRANK pulley is the one doing the driving. You can only express a pulley ratio using 2 pulley's - the DRIVE and the DRIVEN.

I should say, the only way the alt. pulley becomes a factor in blower RPM is if there are 2 belts used to drive the blower. One from the crank to the alt. and one from the alt. (alt. having a double pulley) to the blower.

If that is the case on the JRSC Si blower system, then you have to calculate the pulley ratios seperately by belt then add the ratios.

-TJ

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[Peyomp]

Whether or not it will work depends on how much water you can get through it without sapping too much power and on just how much more efficient copper is at transfering heat than Aluminum is... cause I can tell you definitively that a 1" aluminum core would NOT work. Check out all the technical specs on the site that has the GM sandwiche. Their system is like 3" or so thick and they claim to have had to like specially engineer the core. Don't know if its true, but you get the meaning.

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[dbman96]

Do you have ANY thermal properties information on that core? If not, could you at least post some accurate dimensions of the tubes, fins, etc. and I might be able to throw together some quick and dirty numbers for heat transfer; it would depend on some blanket assumptions, but I could get you ballpark.



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[99SIVTEC]

This core is actually 2.5 inches thick as it sits now. The size of the tubes and fins are not set in stone as of now. Aluminum radiates heat very well, but thats not what we want here. I chose copper because it does a very efficient job of conducting heat. The dimensions from eaton's site are 4.90 inches by 4.90 inches for the blower outlet. The core will be the same size as the outlet. in my above model I used .5 inch copper tubes. As for the fins there were 100 of them, but that again is just a random number. I guess I just need a ballpark of what I need here to have a reasonably efficient core. i'm told .6 to .8 is a good efficiency rating to shoot for. If the core needs to be thicker I can probably go thicker within reason. The added thickness extends up into the manifold itself and does not increase the thickness of the mounting plate. Please help...

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[99SIVTEC]

The civic SI does use a belt from the crank to the alt then the alt to the blower, so the alt pulley is a factor in this. I simply used the overdrive percent number that JR provides. This number in the domestic world at least is always the percent overdriven from the engines speed. This number implies that they have already factored in the pulley dimensions and done the calculations you are talking about. I could be wrong, but i'm basing my numbers on the overdrive percent i've been told.....

The other thing is the blower outlet. The air coming out of the blower is NOT compressed yet. It will not be nearly as hot as the air that is already in the manifold being compressed behind the valves. the intercooler will actually have two chances to cool the intake charge. One when the uncompressed air leaves the blower outlet, and a second time as it builds pressure in the manifold. I would love to build a test bed over the winter, but I don't think my limited funds are going to allow that.

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