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I know a few people have concerns over smic's heatsoaking while sitting in traffic, etc. Has anyone tried mounting an electric fan on their intercooler. On my 91 MR2 it came stock with an intercooler fan and a popular upgrade was to add a SPAL electric fan to aid in avoiding heatsoak. Just wondering if anyone else has contemplated this idea.
thanks max, that is helpful. Anyone else out there using one?
I have been wondering about wiring, because I'm considering using the Mr2 intercooler fan ecu(fan ecu located beside engine ecu) and relay to control a fan of similar specs.
My main challenge is finding the cleanest way to add a relay to the the fd engine bay.
Are we just splicing into the ignition? I dont like that idea because i may hack that up for other stuff
Do you know of any other threads that has some clean relay installation tips?
I put a fan on my ASP large stock mount IC for cooling the IC between runs at autox/track.
Since I dont have AC I ran the positive fan wire to the AC compressor clutch plug and the fan ground to the chassis (after checking that the AC clutch relay was rated higher than the fan Amps).
So, I just pit, pop the hood (gas struts now) and push the AC button and the radiator and IC fans kick on for cooldown mode.
I still use my water sprayer when its super hot out, but now I just spray into the IC duct and it cools very quickly with the fan on.
Just my opinion, I feel a SMIC will always heatsoak once it hit traffic or a stop no matter what. I installed a spal fan and enlarged the openning area of the ducting and still heatsoak on seconds after going less than 30mph. Haven't tried with a vented hood yet but I'm sure it will still heatsoak because of all the heat it gets from the radiator and engine bay.
Also I live in Panama, Central America, so I'm in 90F and up all day.
Yeah, these large size ones are the worst for heat soak because there is no where else for the radiator waste heat off the fans to go besides around the end tanks.
I want to make a smaller double pass U IC that fits totally inside the large 17" x 13" large IC duct. This way the duct would shield the IC from radiator heat and there would be better radiator performance as well with more room for waste heat.
Just my opinion, I feel a SMIC will always heatsoak once it hit traffic or a stop no matter what. I installed a spal fan and enlarged the openning area of the ducting and still heatsoak on seconds after going less than 30mph. Haven't tried with a vented hood yet but I'm sure it will still heatsoak because of all the heat it gets from the radiator and engine bay.
Also I live in Panama, Central America, so I'm in 90F and up all day.
Problem with a non-shrouded puller fan on a thick core is that it will tend to pull hot air from the engine bay back thru the core because it is the path of least resistance. Put a piece of yarn next to the fan guard on the hot side and you will probably see it get pulled against the IC.
I had a similar setup and found that it actually worsened my intake temps. If you think about it - why would the air travel through the duct and a 3" core when it can just pass through the adjacent fins on the hot side? I found using a pusher fan installed on the duct side worked much much better.
The real problem with an IC fan lies in the physics and temperature differences... you've got to move A LOT of air to drop the core temp enough to see an appreciable drop in intake temps. If you're expecting to get close to ambient intake temps with twins and a SMIC temper your expectations.
For example my IC fan dropped the core temp about 20 degrees F in one experiment. That is just where the fan is, so an 8" diameter circle. My intake temp only dropped a few degrees. BUT normally it would have risen, so there is a benefit.
Eventually I am going to put a pre IC thermocouple and see exactly how much my fan drops the intake temp.
Absolutely agree that dumping radiator air on the aluminum end tanks contributes greatly to the problem. I think your air is already picking up so much heat from the heat soaked twin turbo area at idle you are fighting an uphill battle. Every little but helps.
IC fans do help if executed correctly, but you're better off with chemical intercooling as well. I am toying with the idea of AEM WI.
Thats a good point about the non-shrouded puller fan sucking in engine bay heat from the other side of IC.
I only use my puller fan with the hood open between runs, but I have forgotten to turn the fan off during a run and the IC temp when I popped the hood before the next run was way higher.
Thats a good point about the non-shrouded puller fan sucking in engine bay heat from the other side of IC.
I only use my puller fan with the hood open between runs, but I have forgotten to turn the fan off during a run and the IC temp when I popped the hood before the next run was way higher.
Yep! I was blown away by the negative effect. My first test drive I was at a light thinking I was going to switch on the new fan and see my intake temps plummet on the commander. Imagine my surprise when they just went higher and higher and higher.
IMHO you're WAY better off going with some water injection than playing around with IC fans. Water injection WORKS, instantly drops temps like a rock. The AEM kit is fantastic, been running mine for years with zero problems and it does awesome.
I agree. However, the problem I saw with water injection and autocross is you have to be moving and under boost to drop your intake temp.
Sitting in grid or waiting in line for your run you are heat soaking the intercooler. With a functional fan setup you can prevent temp increase of the IC and even lower your core temp. The goal for me is to start off with cooler intake temps, not use up part of run getting them down.
Plus I wanted to avoid the complexity and weight of yet another system on the car. WI is definitely more complex than a fan and relay.
I do think adding the WI to my setup eventually will be beneficial. Two pieces to the same puzzle and I look forward to trying it once I have the time.
Sitting in grid or waiting in line for your run you are heat soaking the intercooler. With a functional fan setup you can prevent temp increase of the IC and even lower your core temp. The goal for me is to start off with cooler intake temps, not use up part of run getting them down.
I'm not up on the current auto-X rules, but if it's allowed, you might want to try this little trick just before you run:
1. Grab a can or two of computer duster gas (aka HFC152A/R152A) and have it handy on race day.
2. Just before it's your turn to run while sitting in the grid, pop the hood and with the can turned upside down to dispense it as a liquid, spray the entire contents of the can(s) onto the IC core surfaces. Goal here is to rapidly bring down the temperature of the IC core, temporarily relieving the heat soak condition.
3. Wear eye protection & gloves while doing this - in liquid state, this stuff can cause instant frostbite on unprotected skin.
Problem with a non-shrouded puller fan on a thick core is that it will tend to pull hot air from the engine bay back thru the core because it is the path of least resistance. Put a piece of yarn next to the fan guard on the hot side and you will probably see it get pulled against the IC.
I had a similar setup and found that it actually worsened my intake temps. If you think about it - why would the air travel through the duct and a 3" core when it can just pass through the adjacent fins on the hot side? I found using a pusher fan installed on the duct side worked much much better.
The real problem with an IC fan lies in the physics and temperature differences... you've got to move A LOT of air to drop the core temp enough to see an appreciable drop in intake temps. If you're expecting to get close to ambient intake temps with twins and a SMIC temper your expectations.
For example my IC fan dropped the core temp about 20 degrees F in one experiment. That is just where the fan is, so an 8" diameter circle. My intake temp only dropped a few degrees. BUT normally it would have risen, so there is a benefit.
Eventually I am going to put a pre IC thermocouple and see exactly how much my fan drops the intake temp.
Absolutely agree that dumping radiator air on the aluminum end tanks contributes greatly to the problem. I think your air is already picking up so much heat from the heat soaked twin turbo area at idle you are fighting an uphill battle. Every little but helps.
IC fans do help if executed correctly, but you're better off with chemical intercooling as well. I am toying with the idea of AEM WI.
That make sense, in my case the fan did pull air from the IC and duct, you can feel it sucking air through the duct openning but just not enough to cool it, I have test it and it just delay the heatsoak while stopped compared to having the fan Off.
Definitely a shroud will help but still I'm sure it will not be enough, maybe with a vented hood and ducting the air from the radiator to not pass through the IC but I'm done trying with SMIC and saving for a upgrade.
In Street Prepared we are allowed internal (intake) water injection. I have thought about it, but from everything I read water injection lowers power, but provides knock resistance.
So, you could run higher boost on lower octane fuel with water injection for more power.
However, since Street Prepared and up are allowed E85 as well as basically any non Methanol race fuel (so 116 octane is fine) we arent limited in boost by octane rating.
We are only allowed external water spray, ice, computer duster, etc off track (in pits) and not allowed absorbent material to carry water on track (competitors have been overlooking the water trapped in the IC fins).
Water to air ICs are allowed ice internally (great for Super Street Modified where FDs are under weight and need to ballast up to weight), but there is no minimum weight in Street Prepared- so light weight is the name of the game for the FD (helps braking, accel and cornering).
That make sense, in my case the fan did pull air from the IC and duct, you can feel it sucking air through the duct openning but just not enough to cool it, I have test it and it just delay the heatsoak while stopped compared to having the fan Off.
Definitely a shroud will help but still I'm sure it will not be enough, maybe with a vented hood and ducting the air from the radiator to not pass through the IC but I'm done trying with SMIC and saving for a upgrade.
My puller fan pulled some air thru the duct as well. Based on the air temps and yarn test it pulled enough air from the engine bay to cancel that fresh air out.
What about a divider in the duct? It would separate the fan side of the ic from the non fan side. I have the Petit cc3 so the duct is large so there would be room for a divider. I’ll probably try this soon and do the yarn trick.
What about a divider in the duct? It would separate the fan side of the ic from the non fan side. I have the Petit cc3 so the duct is large so there would be room for a divider. I’ll probably try this soon and do the yarn trick.
I don't believe a divider on the duct side is going to change the fact that air can be scavenged through the core from the engine bay side.
I should qualify all of this by saying the effect is going to be way more prevalent with a louvered fin. My M2 has louvered fins. If you have an IC with straight fins that basically create a bunch of uninterrupted channels through the core, then I can see a puller fan working without a shroud. Either way, a high CFM fan mounted to a shroud that puts suction on the entire face of the core would be the best all around.
The louvered fins below show how air can easily be pulled across fins.
Those are Spal pusher fans that fit just about perfectly inside the duct. I imagine it's pretty efficient from an air-moving perspective. The IC is an "FD Motorsports" of which there is a newer model that comes with a shrouded puller fan built-in: https://www.rx7club.com/3rd-generati.../#post12396304 The guy who runs that shop is kind of a ****** but appears to make good stuff.
His Facebook page seems to be whats updated, but I seem to have lost the link... He's in Sydney.
Another probably just as good and slightly more affordable option is the Knight Sport "Super U" IC that can be found on RHD Japan. I think the FD Motorsports one is just a clone on the Knight Sports one but with a CF duct and a lipped duct extension (why I bought it).
Mind you, it's winter and the car is down for work right now, and I have not had a chance to test idle air temps with/without the fans running... kind of an important bit of missing information... 🙄
05-01-02, 02:43 AM
