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-   -   Dual intercooler set up? (https://www.rx7club.com/2nd-generation-specific-1986-1992-17/dual-intercooler-set-up-298740/)

import_rican 04-24-04 07:55 PM

Dual intercooler set up?
 
I was curious would I be able to mount dual intercoolers? See this is what I was thinking...have the turbo go in to a FMIC and the piping from the FMIC go in to the stock IC. My thinking is this would make the air cooler since it is getting cooled in the first IC then in the 2nd it just gets even colder. Wouldn't this setup make more power?:confused: I know some of the new audi's or some german car does this?

If I am a dumbass for thinking this call me that but let me know why this wouldn't or would worK. I'm just learning as I go.

Rxmfn7 04-24-04 08:00 PM

The whole reason for front-mounting an intercooler is to get it off top of a hot engine. My guess is that the stock IC would heat up the already intercooled air from the FMIC.. but not sure. Anyway, the pressure drop across 2 ICs would be alot Id think, and with a nice FMIC AITs are already pretty cool. Im no expert when it comes to intercooling, but Id think you would have a decrease in power and response time, that just FMIC alone. I also think this has been discussed before, try a search.

Gene 04-24-04 08:06 PM

Pressure drop across the stock IC is pretty bad. Don't waste your time, just do a nice FMIC or V mount if you're feeling brave, and chuck the stocker into a river.

$100T2 04-24-04 08:47 PM

Re: Dual intercooler set up?
 

Originally posted by import_rican
I was curious would I be able to mount dual intercoolers? See this is what I was thinking...have the turbo go in to a FMIC and the piping from the FMIC go in to the stock IC. My thinking is this would make the air cooler since it is getting cooled in the first IC then in the 2nd it just gets even colder. Wouldn't this setup make more power?:confused: I know some of the new audi's or some german car does this?

If I am a dumbass for thinking this call me that but let me know why this wouldn't or would worK. I'm just learning as I go.

Aside from the fact that the piping for it would be a frickin' nightmare, the stock unit is really not that efficient. Get a nice FMIC or go for a horizontal mount like what Blue TII has, and you'll be all set.

Evil Aviator 04-24-04 09:03 PM

It's probably not such a great idea because the pressure drop of each intercooler will add if you mount them in series, and the additional plumbing would also cause some pressure drop due to bends. BTW, if you don't know what pressure drop is, you can think of it as "negative boost".

import_rican 04-24-04 09:23 PM

:o: okay, that makes sense, I'm not too familiar with pressure drop I seem to have a better understanding... if you don't mind, can you elaborate on horizontal mounting?:confused:

rotard 04-24-04 10:10 PM

According to corky bell, it is far better to mount in parallel re. minimizing pressure drop.

The proposed application would require variable piping lengths for the 2 ICs. Also, the 2 would presumably be different units, so would flow differently. This would, as far as I can see, make the FM unit (probably larger) see much less air, as air would prefer to flow via the less restrictive (due to piping and IC itself) top mounted unit.
Thus the front mount would be pretty much useless.

Evil Aviator 04-24-04 10:33 PM


Originally posted by import_rican
:o: okay, that makes sense, I'm not too familiar with pressure drop I seem to have a better understanding
The turbo multiplies air pressure. As the air travels from the turbo to the engine, restrictions reduce the air pressure. This is called pressure drop.

Example:

1) Air into turbo = 14psia.

2) Turbo multiplies air by 1.8 pressure ratio.
14psia * 1.8 = 25.2psia
25.2psia - original 14psi = 11.2psig boost

3) The air travels through a 90deg turn, losing 0.2psi from the restriction.
11.2psig - 0.2 = 11.0psig

4) The air travels into the intercooler, losing 0.2 psi at the inlet end tank.
11.0psig -0.2psi = 10.8psi

5) The air travels through the intercooler core, losing 1.0 psi.
10.8psig -1.0psi = 9.8psig

6) The air travels into the intercooler, losing 0.2 psi at the outlet end tank.
9.8psig -0.2psi = 9.6psig

7) The air travels through a 90deg turn, losing 0.2psi from the restriction.
9.6psig -0.2psi = 9.4psig

Boost pressure in the intake manifold = 9.4psig, which is what you read on your boost gauge. However, the turbo is producing 11.2psig boost. Kinda sucks to have pressure drop, eh? :)


Originally posted by import_rican
if you don't mind, can you elaborate on horizontal mounting?
Front-mount intercoolers are traditionally mounted vertically in the front of the car. Horizontal mounting means rotating the intercooler 90deg so it is mounted flat like the stock intercooler. This allows the natural airflow (hot air rises) to help with cooling. A horizontally mounted intercooler is a major project, and requires a vented hood to work properly, so it's not the best idea for everybody.

NZConvertible 04-25-04 12:50 AM

Re: Dual intercooler set up?
 

Originally posted by import_rican
...have the turbo go in to a FMIC and the piping from the FMIC go in to the stock IC.
Lets think about that. The biggest advantage the TMIC has over a FMIC is far less piping. The biggest advantage the FMIC has over a TMIC is far less heatsoak. Your dual interooler set-up will have both long pipes and suffer from heatsoak. To make matters worse, there's a lot of pressure loss caused by air moving in and out of the IC's end-tanks. Your set-up has four end-tanks instead of the usual two. All up, this is a very bad idea.

Wouldn't this setup make more power?
No, most likely it would make less.

I know some of the new audi's or some german car does this
No they don't...

jhillyer 04-25-04 07:21 AM


Originally posted by Evil Aviator
...
Boost pressure in the intake manifold = 9.4psig, which is what you read on your boost gauge. However, the turbo is producing 11.2psig boost. Kinda sucks to have pressure drop, eh? :)

Too bad we're not measuring volume drop, because air mass in motion deceives pressure sensing. An example is creating the highest restriction near the throttle. Sense pressure anywhere between the turbo and that restriction and see peak pressure, disregarding misreads from varying velocity. Sensed pressures along the path can mislead, so the important pressure comparison is the turbo outlet with the burn chamber.

Because an intercooler size scales with the need to maintain flow and reduce temperature, effective coolers are enormous, and we'll always see a pressure drop after the intercooler from air mass collapsing from the chill. Volume for volume, lower pressure after the intercooler proportional to temperature drop is good.

Evil Aviator 04-25-04 11:25 AM


Originally posted by jhillyer
Too bad we're not measuring volume drop, because air mass in motion deceives pressure sensing. An example is creating the highest restriction near the throttle. Sense pressure anywhere between the turbo and that restriction and see peak pressure, disregarding misreads from varying velocity. Sensed pressures along the path can mislead, so the important pressure comparison is the turbo outlet with the burn chamber.

Because an intercooler size scales with the need to maintain flow and reduce temperature, effective coolers are enormous, and we'll always see a pressure drop after the intercooler from air mass collapsing from the chill. Volume for volume, lower pressure after the intercooler proportional to temperature drop is good.

I think you are confusing dynamic pressure, static pressure, and total pressure. ;)

I recommend that you pick up a copy of one of Corky Bell's books that explain this in more simple terms. The "Supercharged!" book is a little better than "Maximum Boost" in my opinion. Also, "All About Intercooling" by George Spears is pretty good, although it's more of a pamphlet as opposed to a book. For those who do not have a whole $30 to spend on a book, this website covers a lot of intercooling issues, although I'm not sure if it is quite as accurate as the other references I mentioned:
http://www.are.com.au/techtalk/intecoolersMR.htm


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