18 replies to this topic

[panda]

i was planning on using a saab intercooler with my setup but it was damaged, now i have a intercooler from a ford thunder bird sport coupe, is this a good inter cooler and will it mount ok?
it looks like a top mounted one not side or front!
or should i just try to fix the saab intercooler?

[CRXdan]

Modify the end tanks to fit in a front mount application. I woudl sell both intercoolers and just buya nice one to fit behind your whole front grille, or better yet, go air to water and relocate the battery to the back.

Edited by CRXdan, 12 April 2005 - 06:57 PM.

[tjbizzo]

IMHO the tbird IC is a much better design than the saab one. Is there any way you can mount it without modifying the end tanks? If not then I've got a few others lying around that I might be willing to trade you for it since I don't have a tbird one for my collection yet. Look on ebay to get an idea of what will fit the dimensions of your location. My personal favorite ICs are the >probe/626<, 87-92 supra, wrx, other toyota/mazda 323, and 1g & 2g dsm. And I hate, repeat HATE those looonng skinny ICs that they sell on ebay that are like 5"x2"x30". That's just a poor design plain and simple, but people buy them because they *look* cool and they aren't that hard to fit for some cars.

[rpr]

You mean like this one?

[tjbizzo]

You mean like this one?

<{POST_SNAPBACK}>

Yep! Sorry, didn't mean to dis ya, but I reeeeaaally don't like those. At least yours has slightly thicker tubes than most of them.

[rpr]

Why don't you like them? It seems to be a perfect FMIC for the car.

[panda]

i heard that the saab intercooler might be better then the thunderbirds!
there was an article in grassroots stating that the birds intercooler was
not eficient and and the saab flowed better!
im not sure who to believe?

[tjbizzo]

Why don't you like them? It seems to be a perfect FMIC for the car.

<{POST_SNAPBACK}>

Obviously it will depend on the application, but as a practical and functional matter there are two things that you want an IC to do. First, you want it to cool down your intake charge to somewhere near ambient temp. Second, you want it to do so while causing as little pressure drop across the IC as possible. Those do the first part ok (in fact the intake air is probably mostly cooled off before it gets halfway) but it is the second part that I take issue with because anything that adds heat or causes a pressure drop in the intake tract (or both!) only amplifies problems for the entire turbo system.

For instance, if you have an IC that causes 1 psi more pressure drop than another IC, then the compressor will have to make 1 psi more boost for the two systems to have the same boost pressure at the TB and in the manifold. However that 1 psi more boost is very expensive because it will also heat up the intake charge more, meaning that it needs to be cooled more. You also need to extract more energy from the exhaust flow in order to turn the compressor that much harder, but doing so means that you will need a higher pressure ratio across the turbine. That means that you will have higher exhaust manifold backpressure, higher exhaust temps (more cooling issues), and you will lose more mechanical work with the pistons having to push harder to evacuate the cylinders.

Now, what you will hear from some people, especially those over in the H-T forced induction forum, is that you want high velocity HIGH VELOCITY HIGH VELOCITY in your intake tract. They say this because 99% of them are making two distinctly different kinds of logical errors. The first and less important one is that they know there is a grain of truth to the idea that if you use really large charge pipes that it will slightly increase your turbo lag. Well, it's true, but NOT because of the lower intake air velocity like they think. It's because of the larger charge pipe volume which takes a little longer to fill. The second and more egregious error is that they think their high velocity intake air is a) free, which it isn't, because you have to expend a lot of pressure to get that high velocity (conservation of energy, yO) and it's really pressure we're after because all of that glorious velocity just gets converted back into pressure in the intake manifold anyway, and b ) they think that the high velocity air doesn't cause any problems or have any downside, which it does and has.

I don't mean to totally disrespect those people because H-T has several talented members and others there have a lot of experience with boosting, but I doubt that more than a handful of them have taken any fluid dynamics classes. Well, I have, and while I'm not a supergenius on the subject I'm also not an idiot. The important thing to keep in mind with respect to energy and compressible gas flows is .... nothing is free! If you use energy one place then you take it away from somewhere else, which leads to the real point I'm trying to make, which is ... high velocity air in your IC and charge pipes is bad! Very bad! Why? Because Mother Nature is a bitch, that's why. The aerodynamic drag on air flowing thru a pipe or an IC is basically a function of the SQUARE of its velocity. This means that air flowing twice as fast will have FOUR TIMES the drag and therefore four times the pressure drop! Let me give you an example with your (johnnieracer?) IC there. The core looks to be approximately 6"x30", correct? Suppose you were to chop it vertically in half down the middle, place one half on top of the other, and make new endtanks so that instead of an IC with 7 tubes 30" long you now had an IC with 14 tubes 15" long. Do you think they would perform about the same? Well, for low volume flows they would perform about the same. Loafing around town, cruising on the highway, up to about 50-100hp there wouldn't be much difference, but once you got volume flows large enough to see high air velocity in the charge pipes and IC the 12"x15" IC would start to outperform the 6"x30" IC. What happens is that the long skinny IC will have velocities twice as high as the shorter wider one, which means it will have four times the drag and therefore four times the pressure drop. They have the same internal volume and the same surface area inside the tubes, the air spends the same amount of time in the tubes (1/2 the distance x 1/2 the velocity = same time), yet the shorter wider one will have 1/4 the pressure drop. It will also cool the air more because the energy that was wasted on friction in the long skinny IC gets converted directly into heat in the air. Yep, Mother Nature, she's a beeyotch all right. :looks around expecting lightning:

However, all is not lost. The one you have there should be OK up to about 225-250hp or so. Anything more than that and you really should consider getting something bigger or adding a second one. Please note that all of this is just my own humble and imperfect opinion so take it with a grain of salt. It's perfectly fine if others disagree with me but I really don't want to start any kind of debate about the subject.

p.s. Sorry for the long post. I was going to make an analogy of the long/skinny and short/wide IC's to having two helper monkeys fetch water for you, one a crazed cappuchin monkey on crack that could run twice as fast and make twice as many trips, but could only carry 1/2 as much water at a time and would spill a lot of it (high velocity & wasted resources), and the other a slow walking orangutan who could could carry twice as much but only half as fast and he wouldn't spill as much water (low velocity & energy conserved), but that seemed a bit over the top. Oops, now it's even longer! Oh well. Sorry again.

Edited by tjbizzo, 21 April 2005 - 11:50 AM.

[CRXdan]

didnt even bother reading your post
and rpr, that intercooler is awesome. I like how you modified the endtanks instead of runnign the charge pipe around the frame rail

[zakats]

by george he's got a good point. I do have a few questions though. I dont think Im quite as well oriented with fluid dynamics as you although a few of my classes have gone into the territory enough to understand the principals. All what you're saying is true to a point just as the "other guys'" way of things right? ALL of this varies and depends on what kinda setup you're using right? Like what kinda cfm @ whatever psi, tubing volume, ect... although it might not look like it, Im going with what you said since you're right. But what im getting at is that given the right setup, the longer ic will perform pretty well...I think i had a diff point but im really tired... something about reguardless of using the right setup that it would still be better to use a diff design of IC *I* THINK!
--zak--

Edited by zakats, 13 April 2005 - 11:49 PM.

[rpr]

Wow, that's great information. And yeah, I'll be below 200hp for sure, so that shouldn't be as much of a concern. Something to think about though.

And the IC was made by Masta, along with just about everything else.

[Surestick]

Good post tjbizzo.

[bisenuno]

Just giving my 2 cents ,i heard the starions intercoolers wrk real well!!

[JEFFtheJ00la]

wow, i feel informed. great analogy. i wish you would have put that first though so i diddnt have to read all that, lol.

[zakats]

I might have the hookup on the starion IC's I've got some star/quest ppls
--zak--