CFM vs. cooling of FMIC

[RocketBoy]

I haven't found a definitive answer to this yet. Is there any correlation between the CFM a front mount flows and how efficient it is at cooling the air charge? Basically, if two intercoolers have the same pressure drop and one flows more air, will it also cool the air more? Are there any proven studies that side-to-side cools more than top-to-bottom?
thanks,
Keith

 

[KenTSIII]

The longer the tubes.. the longer the air is in the IC... the better the IC cools.. hence side to side cool better.

 

[turbolover2]

If you have two intercoolers with the same pressure drop, then the one with more internal flow area would be better. The one that allows the most air to flow through, would also cool the most air. But it has to be in the right configuration. For instance, if the core is too thick, although it may flow a lot of air through it, the ambient air will not go through it as easily. In that case, a longer, thinner core would be better. Internal flow area and frontal area (the area that gets hit with ambient air) are the important numbers here. To answer your question, all other things being equal, the one that flows more air will be better (unless it's way oversized, then you will have a lot of lag).

It seems like most top to bottom cores have more internal flow area than side to side cores. But if the guy who runs Indy Race Cores says side to side is better, well, I tend to go with the expert opinion. As far as proven studies, I'm sure there are some, but I don't know of any. Maximum Boost has an excellent chapter on intercooler design. If you haven't read it, I highly recommend it.

 

[DCJ98GST]

Originally posted by KenTSIII
The longer the tubes.. the longer the air is in the IC... the better the IC cools.. hence side to side cool better.

Yea but according to the bernoulli's equation, the air may travel twice as slow in the top-bottom intercoolers because they can have twice the amount of tubes open to flow compared to the side to sides.

Therefore the air stays in the intercooler the same amount of time.

I like the top-bottom intercoolers because they can cool just as well but yeild significantly less pressure drop!

Remember for every psi of pressure drop your side to side intercooler yeilds, your turbo has to make up in psi causing it to run more out of its efficency range and yeild more heat.

Of course this is all theory and talking to alot of people with intercoolers, not personal experience.

 

[G50trim92]

I've read Maximum Boost, that book is filled with gobs of great info.
Corky gave me the impression that the top to bottom intercoolers were generally better. Most of the really high hp cars were all running top to bottom ic's.

 

[KenTSIII]

What are all the really fast cars running now (hint... it's not top/bottom)? Top to bottom flow better due to the greater # of rows & due to the fact that the air is not as dense (cool) when compared w/ the side to side configuration. Another reason that most DSMers go w/ side to side is due to the easier configuration & better packaging of the complete system. You can fit a much more efficient/larger core than you can w/ the top/bottom. Due to the fact that you have to add an extra 6" (3" on each side) to the height of the core... you can only fit a 6" tall core in there (on a DSM & other imports). Corky Bell is referring to V8s in his book (If I remember correctly) which normally only put out low boost & pressur drop is a greater factor at lower boost. If you want to get into the whole pressure drop debate... we're only talkin a fraction of a psi from side/side to top/bottom... and that could be alleviated w/ a 1/8 turn of the MBC.

 

[RocketBoy]

Basically, what i'm getting at is the fact that Corky Bell said that top-to-bottom was better. However, look at what the pros are running; top-to-bottom spearco intercoolers. The DSMperformance intercooler flows 1280 @ 1.5 psi drop. Is there anything else that competes with it?
thanks
Keith

 

[KenTSIII]

Look at what the pros are running? You might want to look again... everone that I see is running a side to side. Also alot of poorly designed top to bottom FMICs (in/outs on the same side) only use a small portion of the IC & the air has to make a 90 deg turn to get into the tubes. I definately think in the right application w/ the correct tank design that the top to bottom might be superior.. but you can't do that on a DSM or most turbocharged cars.

 

[turbolover2]

Originally posted by KenTSIII
Corky Bell is referring to V8s in his book (If I remember correctly) which normally only put out low boost & pressur drop is a greater factor at lower boost.

He covers all types of cars in the book, even Formula cars that run very high boost. But the intercooler chapter doesn't mention any specific cars, just intercooler design.

So, the top/bottom IC is better in general. But DSMs usually benefit more from the side/side because of configuration of the pipes and the fact tht you can fit a bigger core with a side/side on a DSM.

I think that covers it.

 

[G50trim92]

So unless you actually need a GIANT fmic on your dsm the average sized top to bottom would be a better choice. Unless your going for 9's and need to be able to fit a monster cooler in there.

 

[DCJ98GST]

It depends on what you want to do, and what your setup is going to be. Top-bottom flow ICs are good for road racing and autocross because there is minimal pressure drop across the core. This means better spool-up.

However, if you want maximum cooling for the charge air, go with a lateral flow IC, since only then can you get a bigger core to fit. The laterals typically have more efficiency because the charged air has less routes to travel, and the air will use the whole core.

Notice I did not say that the air stays in the core longer with the lateral's because if you are comparing the same size lateral core to the same size top-bottom, (as long as the same amount of core is being used) the air stays in the core the same amount of time.

The main problem with the top to bottom coolers on the market now are that they have the endtank outlets on the same side, and the air uses only the first part of the core.

I would suggest getting the RRE spearco top-bottom core with endtanks on opposite sides, then the air has to use the whole core. This will make the top to bottom IC just as efficient as the lateral's (with the same core) and have better pressure drop. Best of both worlds.

 

[mike9146]

Don't forget about the fact that top-to-bottom designs require that the endtanks partially block your radiator. Most of the overheating stories I hear about with a FMIC are top-to-bottom. A Spearco 2-216 like IRC's "Race" core is wider than the radiator, so there is no solid wall blockage. BTW, the IRC Race core cools so well that a local club member is hitting fuel cut with a 2G MAF at only 13 psi on a 60 degree day. I think it's effectiveness speaks for itself.

Mike C.

 

[iwantawd]

nice post but there are some things i need to say because if there is one thing i do know about its designs of intercoolers. top to bottom is better for cooling the intake charge . whether or not it makes overheating worse, ill deal with that when that problem comes along. top to bottom of course has less pressure drop and no i personally refuse to believe that its only 1/8 psi, and the bigger the intercooler the worse it will be. if everyone is worried about the endtanks being on the same side, who cares. install a baffle to spread the air out. if you dont understand what this is go pick up maximum boost for a great picture explanation. the baffle should be installed whether or not the endtanks are on the same side or not anyways but if you guys dont think so whatever. whether or not everyone else in the tuner mags are using top to bottom is not a concern of mine, i dont care. take a look at the pictures with an exposed indy car or some of those sub 10 sec import drag cars, what do you see... top to bottom intercooler. the real racers with engineers designing their systems know what works the best. im out.

 

[DCJ98GST]

I always thought that baffling the end tanks so the air is directed across the whole core would be a good idea. But, I never have seen any manufacturer's provide a product like this. Do you know any? Because I don't know how to weld.

 

[iwantawd]

ive never seen anything for sale, it will have to be custom. i doubt it would be that expensive you only have to do it for the inlet

 

[Kevin Jewer]

The main reason I like top to bottom better is that every row gets exposed to ambient airflow... On a side to side usually only half of the rows get exposed to the front bumper opening. 95-96 cars have it the worst obviously. But I'm still going with side to side for packaging reasons and to fit a huge core. I might switch to 97 bumper cover to get more of its hieght into the opening.

 

[KenTSIII]

iwantawd.. mind telling me how a top to bottom cools the intake charge better? also if you use a baffle to split up the air flow.. you still have the same effect of the air only using the last 25-30 % of the FMIC.. but now the air is divided into 2 (using one baffle) & so at most you'd be using 50-80% of the FMIC... but since the air is divided in 1/2 I doubt that the % change would be linear. Just because something is better on paper.. doesn't always work out to be better in the real world.
Let's look at the DSM world for a min (since that's what we're in) look at all the top guys (10 sec & less) & what they use:

Dave Buschur 7.8 @ 171 side to side
Sean Glazer 8.8 @ 153 side to side
Gary Marsh 9.5@151 side to side
Marco Pasante 9.6 @ 141 side to side
John Sheperd 9.6 @ 147 side to side
Dan Cokic 9.6 @ 142 side to side
Kevin Lawson 9.8 @ 143 side to side
Jeff Hill 9.8 @ 142 side to side
Curt Brown 9.8 @ 145 side to side (1st IRC race core in the 9's)

That just happens to be the top 10 fastest DSMs... times taken from dsm.times.org. Curt Brown's time was just ran last weekend & hasn't made it to the times page yet... The other times may have been updated also.

These people have their choice of any FMIC that they could possibly want to use. They all choose side to side. Do you honestly think that if the top to bottom worked better that they'd still be using side to side?

 

[IPT]

I have the dsm performance top to bottom. IT wroks great for the 2.25" in and 2.5" out setup. I was looking to go to a 3" uicp. That would be VERY hard to package in a Top to Bottom IC.

I would guess that the top nine people are all running 3" IC piping. That would be a VERY good reason why they run side to side instead of Top to Bottom.

As far as a street car that only has 2.5" piping packaging the top to bottom is not that bad.

 

[Jehu]

I think that main disadvantage of a top to bottom intercooler is that a practical configuration does not alow a thick enough endtank to ensure adequate flow distribution. That's probably why the fast guys are not using it.

 

[tjh-dsm]

A huge advantage to the side-side flow is that it allows much more air to flow to the radiator than the top-bottom b/c the top-bottom endtanks block air from flowing through, whereas side-side does not b/c end tanks are on the sides. People who think overheating is something they'll "figure out when it happens" are just setting themselves up for trouble. You like warping heads? Changing headgaskets? You better.

Many more people have overheating problems w/ the top-bottom than the side-side.

 

[iwantawd]

ok bud (kents111) i did a little research of my own after seeing what you wrote because im pretty confident about this and i went and looked for a picture of the intercooler. when you said that his was side to side i got to thinking alright maybe this thread has been a little confused. typically fmic are longer than they are tall which is why i like top and bottom inlets and outlets. but there are also intercoolers that are taller than they are wide, just not on anybody's car here. when the intercooler is taller than it is wide then a side to side set up would be the best. my point is david buschur's intercooler is so big its almost a perfect square, soooo it wouldnt matter if its top and bottom or side to side.

 

[iwantawd]

as for that part about the percentage of the intercooler being used, dont think that the side to side fmic on the market that we would buy use up 100 percent of the ic because the endtanks designs USUALLY suck. there are a few out there that are nice but compared to a nice top/bottom setup it doesnt hold up, i think. everyone has opinions but i do research a lot, i dont know what kind of backround or experience you have.

 

[iwantawd]

kentsiii, any feedback on this?

 

[talonted_one]

I'm sorry to bring back this heated thread, but I have been doing alot of research on the top-bottom:side-side IC debate....

and how i see it this thread is in complete. no rewal resolution has been made.

lets here from some of the super DSM wise men on this subject.