Intercooler Flow Theory

[DanaT]

So I was thinking about the DSM setup.

It seems to me that a larger SMIC isn't as bad as many people think and that the best setup would be a liquid/air intercooler.

I think the BIG advantage of the FMIC is simply the size of intercooler that can be put in. After that, it is actually not as good of an idea because now engine cooling is affected. It disrupts flow to the radiator and also uses hotter air to cool the radiator. In additon, I have my doubts if it has as good of airflow as everyone believes.

I think the SMIC intercooler is in a very good location. Why? Because the SMIC has two sources of airflow. It has the higher pressure from the front scoops (so essentially it is a FMIC in a different location) but it has the advantage of being in the wheel well. Why does this help? Air flowing over the wheel wheel actually creates a negative pressure (vacuum). Many times it is easier to create flow with vacuum than with pressure. So while you have air pushing in fron the front, you have a negative pressure on the rear effectively increasing the pressure differential and theirby increasing flow.

So, looking at the dsign of the 2G eclipse front end (97+) there are two symetrical intakes with the passenger side having an intercooler and the drivers side having empty space with a block off. What seems to be the best design to me would be to run two small yet efficient (read motorcycle) radiators in these locations and then run a air/liquid intercooler.

But, in general, with the air flow characteristics, I think that for a given size of intercooler (that being having the same size) that the SMIC would be more efficient than the FMIC. Has anyone tried to put the stock SMIC in a FMIC position to see if it is the flow or size that is giving the FMIC intercoolers an advantage?

-Dana

 

[rbwtrans]

3000gt's use twin SMIC's. It's possible but with a lot of piping. FP makes a very nice SMIC that is larger with 2.5in in/out. One of my customer's cars has this and says he runs 19psi with no knock, and it also solved his overheating problem.

 

[rbwtrans]

My only issue with water to air intercoolers is the additional plumbing and separate cooling system required. As you mentioned the motorcycle rads would work, but lets not forget the additional pump (electric, most likely) It just seems like a nightmare.

 

[the_mork]

The DSM SMICs just aren't big enough. Putting a Supra SMIC in is a big improvement. As for the air to liquid intercooler and the dual intercoolers? They've both been tried. Dejon (I believe) created a dual intercooler setup but it never took off and wasn't that efficient or cost effective. As for the air to liquid intercooler they are supposed to work very well but will heatsoak over time on a street car so you would have to either use dual maps or carry water with you and pull over every once in a while.

Hahn and Dejon also both made bigger SMICs for our cars and they are probably better than Supra intercoolers but they are also harder to find and much more expensive.

 

[rbwtrans]

I was mistaken. My customer's car runs a Dejon SMIC. Very nice.

 

[TALONTRAX]

I`m running a Hahn Racing large core smic in the original location with their super 16G turbo. I run 16-18 psi regularly with very little or no knock (still tuning for my new 8:8-1 6 bolt stroker). I really don`t think you need more cooling than what that provides on a street driven car . . .

 

[the_mork]

I've certainly been happy with my Supra SMIC but we'll see how well it holds up as I add more fuel and tune more aggressively this summer.

 

[pboglio]

Wheel well is typically a high pressure zone as well, this is why race cars run louvers on top of the wheel well and an exhaust vent at the rear of the well. DSM's have neither.

You can make an air to air front mount run decently, you just have to be creative.

I bypass some air up and over the I.C. directly into the radiator thru 2 openings in the front bumper cover. A high speed fan wired 100% duty cycle helps tremendously. To lower the pressure differential directly behind the radiator core I've used in the past a small vertical plate mounted directly under the front bumper that trips the airflow under the car. This usually worked at around speeds of 40 mph and up and can be seen on the logger yanking the coolant temps down another 3*F with quicker pull down times. An air-oil cooler will shift some of the engines heat load away from the radiator. Vented hoods also would create a larger pressure differential and assist the radiator & front mount intercooler. Bigger radiator, cooler thermo, surficant agent (i.e. Redline Water Wetter), higher water to glycol ratio, better exhaust manifold/turbo heat shiedling, etc. etc. all help.

I have no problems cooling and in fact have had massive over cooling in colder weather during WOT 4th gear pulls. I've run a small upgraded SMIC in the past and there is no comparison to a properly sized FMIC in terms of recovery between pulls. You can beat the hell out of the car and the FMIC will recover within seconds for another pull over and over again. Same goes for a well setup radiator cooling system.

I'm not an expert in this subject, but people have tried to run small water/air heat exchangers and have had not great results. You'd need a core as big as the main radiator to do the job properly.

 

[the_mork]

I'm not an expert in this subject, but people have tried to run small water/air heat exchangers and have had not great results. You'd need a core as big as the main radiator to do the job properly.

Or you can dump in cold water and/or ice between runs which is why that type of system is usually considered a track only mod, it works great but isn't practical for road use.

 

[andy4g63]

The only car, that actually uses successfully 2 SMIC and makes big power is 300ZX TT.
Intercoolers have 2 most important characteristics and FLOW, it is just after these two and they are COOLING and Pressure drop. Besides how it cools, which is important, cause discharge temp, on a turbo car is somewhere between 220-235*F, that is why SMIC is not so efficient. Most important is the Pressure drop/ the lesser the better/. If the FMIC has more pressure drop, this causes the turbo to works harder to compensate for the losses, therefore pumping harder and increasing the temperature of the air going into the motor. This is valid very much, between shifts and for drag racing. It doesn't apply for a normal driving/cruising on the HGWY.