Black Blown 02

I got a Griffen Intercooler like PSJ's 4.2" X 14" X 20". It will flow 1700 cfm according to Griffin.

It is replacing my tiny ATI unit 3" X 18" X 6".

I only plan on pushing around 900 cfm through it max. Are there any problems with oversizing this much? I figured it would work well because there would be hardly any pressure drop. Am I missing anything?

JZ 97 SS 1500

iTrader: (2)

You will have more pressure drop with that large a core...plus some other factors such as core type/efficiency and whether the unit has been pressure tested.

Jose

Black Blown 02

Can you explain?

andy98Z

iTrader: (4)

I think he means, scince their is more volume in the intercooler you will lose a larger percentage of boost. So you would have to turn it up slighty to make the same power. This is only if the larger intercooler is the same amount efficient as a smaller one.

Black Blown 02

I've heard that the stock ATI unit has a 3psi pressure drop at 500 hp. How could a larger free flowing intercooler drop more?

My thinking is, the small intercooler acts as a restriction, where the bigger one wouldn't restrict as bad. Giving you less pressure drop. Am I totally off?

JZ 97 SS 1500

iTrader: (2)

Well first this can get really complicated and time consuming, but the summarized version is. Take 2 IC's one with lets say 850 ci volume and the one you have just orderd which is 1176 ci volume. The first unit will cool the incoming air to 110 deg's, the other unit to 100 degs. The first unit will have only a .85 pressure drop, the other a 1.5 with a core that size. The added pressure drop will cost you more hp then the added gain in temp drop. Like I said it can get more complicated then that. The other is Griffin typically uses tube and fin, which is an outdated design and doesn't work as well as a bar and plate design. So your having to run a larger core that a bar and plate design can match with alot smaller core. The other thing is, some of the Griffin cores tested in the past had quite a few pin hole leaks, and where they are welded and brazed, was not pretty. Also where are your end tanks located...if they are on either side on the IC where you can draw a horizontal line, then thats not a good configuration since your not using but maybe 40% of the actual core. Also make sure the endtanks are not squared edge tanks. That will add turbulence and also add to more pressure drop, which can be as much as an additional 20%.

Jose

Black Blown 02

OK, heres what I don't understand. Lets say you flow 60 lb/min of air read at the MAF. If you install a larger intercooler, your supercharger is still pushing that same 60 lb/min, right? How would you lose hp? I can see losing boost because of cooler air not taking up as much space, but shouldn't power stay the same?

JZ 97 SS 1500

iTrader: (2)

Like I said it can get complicated thanks to the laws of thermodynamics...lol.

But here is a good read for you....would take all day to type it...lol...

http://www.gnttype.org/techarea/turbo/intercooler.html

BTW, it may not address all your concerns though, but it will get you on the right path...

Jose

Black Blown 02

Thanks for that link. Very good reading. I couldn't find anything in there that told me I would lose power with a bigger intercooler though.

I'm not saying you're not right at all. I just want to learn how this is possible.

Pro Stock John

iTrader: (34)

... Bigger space through which to push air. That would be the concern.

I think it will be fine.

Black Blown 02

PSJ, is you intercooler a tube/fin or bar/plate?

Do you have any intercooler outlet temp numbers?

buschman

I think the idea is that with more volume you have a greater degree of compression. IE like in cylinders. We run less compression to run more boost. Same principal with the intercoolers. More volume requires boost. But more volume also can equal more surface area to cool the compressed air. So there is a trade off in there somewhere. It's like the difference in squeezing one extra person in a phone booth when the other two are already shoulder to shoulder. Versus trying to squeeze same person into a banquet hall. Even if everyone is shoulder to shoulder, it would be much easier to cram that extra person in. So the air molecules in the larger intercooler have more room to squeeze together. Which means the blower is gonna need to spin more to achieve the same boost level.

I'm no engineer, but that's how I make since of it.

Mike

427

iTrader: (3)

Good analogy.
The only problem that may creep up is the amount of air passing thru is so low that you won't be using the whole intercooler and may superheat a small section.
Say you let the people into the room and they come in a double wide door and go strait thru to the other side right down the middle of the room to another double wide door. All there heat is in the center of the "core". Now if you send to many people in (a 1psi drop) they tend to spread out and use the whole room(core) causing the whole room to get warm thus helping to reject heat.
The intercoolers that cool the best are usually the ones with the worst drop across. The "best one's seem to have a 1 psi drop in my experience. That being said I still would rather have one thats to big than to small!!
Hope you can make heads or tails out of this.
Kurt

Black Blown 02

That makes sense to me. The intercooler that came with the ATI kit, only has 6 inches of length to cool the air. I see about 60 degrees temp rise in a 1/4 mile run. So it's really restrictive, and doesn't cool well. So I think even if my new intercooler is too big, it has to work better than the tiny ATI.

Pro Stock John

iTrader: (34)

Right, you are going to be better off than you are now.

My temps only go up 10F during a dyno pull.

My Griffin is whatever they do for all the intercoolers. I love mine. When I priced out other air/air FMIC's they were all like $1000!

parish8

iTrader: (6)

i think the presure would only drop if you made the intercooler longer, if you only made it wider or taller it would only be better as far as cooling and presure drop.

Black Blown 02

Thats how I see it too.

chpmnsws6

iTrader: (70)

you get more lag but its WAY worth it. i loved the big IC i had on my DSM

red ws6 99

The efficiency of intercooler is very much related to the velocity and turbulance the air gong through it. The velocity and turbulance also affect pressure drop. If you go with a way oversized intercooler you will have a hard time filling the intercooler which will cause a pressure drop (but for different reason that two small an intercooler) . The intercooler will be less efficient because the air turbulance will be lower which makes efficiency drop (as stated earlier because effectively less surface are is being contacted and less molecular energy is being dissipated). Of course everything is situation dependent. At least that what I remember from fluid dynamic and thermodynamics classes.

Gary