Fatty_FC3S

Ok, i have a good question for all you tuners out there...

Ive noticed that almost ALL cars with front mount intercoolers (rx7's as well) have the intercooler "tubes" running from left to right with the endtanks on the left and right side of the intercooler.

In corky bells book, he states that its better to have more tubes than longer tubes since this is supposed to offer less pressure drop and more flow (which seems to makes sense). For instance, if you had a 20" (length) X 10" (height) intercooler, you could have essentially twice as many tubes if you had them positioned vertically instead of horizontally.....

So my question is, if the vertical tube design is said to be the better way to go (by mr bell), then why the hell does everyone seem to have the horizontal tubes on their front mount coolers???? Comments, design theories and real world performance ideas are apprecieated! Lets hear those ideas!!!

artowar2

I remember that from the book-- good question!

setzep

I think it's just a trade off. Long tubes-more heat transfer, short tubes less pressure drop. But I think it comes down to what will fit in the area that you have to work with in the car.
In my car a square I/C makes most sence (FB) so I guess it doesn't matter which way the tubes run

maxcooper

It isn't really clear that long tubes would increase heat transfer that much. The time the air spent in each tube would be the same if they were long or short. Long would probably toss it around more, which could increase heat transfer, but I don't think it would be twice the heat transfer or anything like that.

I think the reason it is done on the FD is for space. FMICs do seem to get "enough" internal flow area anyway, so it is probably a reasonable compromise. But it still seems like an IC that flowed from top to bottom (or B to T) that took the whole mouth of the car would offer ideal flow and excellent heat transfer.

-Max

Fatty_FC3S

So far the answers are very good, but i would think there must be SOME reason that the horizontal tubes prevail almost unanimously over the vertical design.

The only racecar i know of that uses the vertical design is Cam Pettits 3 rotor FD racecar. It has a HUGE (long) intercooler that has the vertical tubes. His car seems to do quite well!

One other thing that i thought of:

With the horizontal design (many, not all) the end tanks are visible in the mouth of the car. These tanks are usually about 2.5 inches wide times 2 tanks, giving about 5 inches of "mouth width" that is wasted for potential airflow going to the radiator (flat solid tanks arent very aerodynamic nor does air flow through them like it does through the core). It would seem that having a vertical tube core that was the width of the horizontal style core (without the horizontal endtanks included in the measurement) would allow for equal cooling area....BUT....the space that WOULD have been taken up by endtanks could now be open for fresh air to flow into the radiator!!!!

Does this idea make sense to anyone? Seem credible in its reasoning???

Keep those thoughts coming, we want the best for our cars after all. Its not like we are honda owners and we just take anything as gospel "just because".....

Fatty_FC3S

Sorry this is off the subject.....

Max cooper, your saying is below your avitar is awesome! LOUIE!!! I really miss "The State"......

Anyways, on with the intercooler theories!

BLUE TII

iTrader: (9)

How do the dynamics of airflow fit into this?

Since it is a high velocity system I could see a lot of turbulence caused by flowing from 2-3" IC piping into a huge 20-30" long endtank and into many many more tubes.

VS 2-3" piping into 8-14" long tapered end tanks into many fewer tubes.

Like everything else, it is probably a compromise...Maybe compromise between pressure drop due to long tubes VS pressure drop due to high turbulence?

maxcooper

No one caught the reference (or at least didn't post about it) for weeks and you are the second to mention it today!

As for the flow issue, it probably depends on the actual design. It seems like an IC where the air came one end of a long tube/tank on the top and then flowed down through lots of tubes and then into a tank on the bottom and straight out the end of the tank would be quite good. This general design was one of the things I liked about the SR horizontal IC -- it required one less 90 degree turn than most ICs. Most seem to flow in one direction, turn to flow through the tank, and then turn again to flow through the IC tubes.

-Max

neevosh

I was wondering the same thing. Having more passageways instead of longer passageways. Instead of having it like this. Endtanks on side.
____________
/ l--------------------l \
< l--------------------l >
\ l--------------------l /

Make it like this. Endtanks on top and bottom.

_____________ _
/_____________l_
l l l l l l l l l l l l l l l l
l l l l l l l l l l l l l l l l
{____________/

89S13

Ok here's my 2 cents. I think it all comes down to CFM if you have enough flow through the horizontal type IC then that is probably the better IC to go with because it will cool the intake charge better because of its long path through the IC. And also taking into consideration that most IC manufacturers are gonna build an IC for the masses, meaning that most of these IC's will be used with stock or generally small upgrade turbos, so high flow is secondary to heat transfer. People generally go with whats available hence the popularity of horizontal type IC's. If you go to cartech.net you will definetaly see that Corky practices what he preaches, but I do feel that you can have too much flow. For example, both Cartech and Spearco sell intercoolers for 86-92 Supras with very high flow ratings (1080 CFM is quoted for the Spearco) but how often does an owner of that type of Supra need that much flow? Very rarely is what I have gleaned from the Supra forum's. Those IC's probably would have had better heat transfer if they had the horizontal rather than the vertical design and the loss in flow would not have had a negative impact on at least 95% of their customers.

maxcooper

Flow is not a binary measure. If a core flows 1080 CFMs, all that means is that the pressure drop reaches some chosen level at that flow level. Less pressure drop is always better, so more flow is always better, all other things being equal (which they rarely are). You can't have too much flow as a rule, but at some point other considerations come into play that chasing more flow is not worth the compromise in another area (budget, packaging, heat transfer, whatever). The pressure drop starts to increase exponentially with flow, and the cores are usually rated at a flow at which the pressure drop just starts to ramp up. So generally, I do agree that having a core rated for tons more flow than you actually are putting though the core is only slightly better than one that is merely rated a little higher than you need. Having a core rated for two times your intended flow is probably only a tiny bit better than one that is rated for 1.2 times your intended flow. It is still better (ignoring the volume), but not a whole lot better, so other considerations become more important.

Don't forget that the air will be in the core for the same amount of time for a 10x3 core that is 24 inches long or a 3x24 core that is 10 inches long. The longer, narrower core may have the air hitting more turbulators, which may improve the heat transfer, but I am not sure that would offset the extra heating it would get from being compressed more to yield the same pressure at the IC outlet because of the pressure drop. If you are pushing the flow limits of the 10x3, 24" long core, you would probably be better off with the 3x24, 10" long core in that case.

EvilAviator once made the point that core dimensions don't determine the flow capabilities on their own. After reviewing a bunch of IC data, it became clear that he was right. It seems likely that some of the front-mounts use tube and fin cores that flow a lot for their internal flow areas when compared to other IC cores, and thus can somewhat afford to be modest in their internal flow areas and still not have a lot of pressure drop. In that case, the core length and front-mounted positioning still offer a good charge temperature drop.

Bar and plate cores tend to not flow as well for the same internal flow areas, but seem to be preferred based on their efficiency, so you have to be careful to use a core with a large internal flow area if you go for a bar and plate setup.

I haven't actually seen any good data on the relative merits of bar and plate versus tube and fin cores. What I have posted here is speculation based on rumors, observations of various ICs, and real data for the bar and plate cores. It would be interesting to do some flow tests on some tube and fin cores for comparison.

-Max

RX-Heven

iTrader: (1)

I just went through all these questions last week with Spearco after recieving Corky Bells book and reading the same thing. Spearco told me that it basically comes down to a trade off, and that their cores, go figure, are the best of both worlds We were specifically talking about the opening of the 2nd gen. and maximizing the frontal area. Depending on the layout of the opening vs. cooling needs, the horizontal layout typically is the better choice given the same frontal area, due to the fact that the total area of the endtanks is smaller with that design plus they are not in the direct path of the raiator, thus allowing better flow to the radiator. Plus the overall size of tghe intercooler is smaller given the same frontal area (with the horizontal flow type). So by increasing internal flow area with the verticall flow, you have increased the internal area of the endtanks also. Increasing internal flow area also increases lag. They also told me that even though the vertical flow type does indeed provide greater internal flow, the air must make a sharp turn to flow through this type negating the advantage. However I was suspect of this claim since they were trying to sell me a core. Later, I noticed in Bells book he seems to contradict himself regarding this issue. He claims the vertical flow has less restriction due to greater internal flow area, but later states that every 90 degree turn a loss of 1% of flow will occur, so all turns should be kept as large a diameter as possible. Well you couldn't have a smaller size diameter than with that endtank design. So I think Spearco may have been right about the benefit negating itslelf.

In the end I chose the exact (I think) same intercooler that Evil Aviator runs. It is their highest flowing with lowest pressure drop and largest frontal area that could fit. 26x15.6x3.5 horizontal flow.

E6KT2

And how much did you pay, if I may ask?

RX-Heven

iTrader: (1)

$1147
Pricey, but still cheaper and much better than any kit out there

Cheers!

3.5 inch thick... wow.

bkapold@aol.com

Before i bought my Spearco I thought about all this horizontal and vertical stuff too.... I ended up with a 27 x 8 x 3.5 horizontal, mainly because the routing of the tubing wouldn't have been a straight shot if it were vertical. A vertical core would have put the end tank on the bottom and there would have been a few sharp bends....Corky Bell also says to keep things straight, so I figured what am I gaining by having a vertical unit/ end tank on the bottom, when I have al these extra bends..
I have an HKS 40mm external wastegate w/ 10psi minimum and I turned the boost as low as it would go and I'm @ 9 psi, actually a shade over 9psi.....Howz that for a pressure drop? Of course there are other things that are in that equation too, but I like a clean straight shot....I think thats what really helps

Brad

T2`n`Conv

Brad,
any pics of your setup? Is the 27" with endtanks?

Thanks,
Brian

RX-Heven

iTrader: (1)

It must be, and I bet he mounted it directly behind the front bumper, like the GReddy unit.

bkapold@aol.com

Hey guys,

Mine is mounted benind the front bumper in the 28" opening...the Spearco 27" is w/ end tanks

I can never figure out how to send photos, but -email me and you can post them.... The IC setup is just the the Soul Assasin guy...and no I didn't copy him

e-mail : bkapold@aol.com

Brad

rotormatt

How come you see lots of rx2's snd 3's with 13b turbo conversions and they have intercoolers that are extremely tall. how come you never see those on series 4 and 5's. Is there a differance between Rotory and Piston motor Intercoolers???