intercooler on 89 rx

[mikeshoup]

Fair enough

[WJM]

What intercooler were you using? Is it top or front mounted? A top mounted intercooler would get almost no air flow on a dyno unless it had a fan installed to force air over it, while on the road it would get considerable airflow without such a fan. Is it possible that your intercooler was simply heatsoaked from lack of airflow, and not operating at all on the dyno?

 

I had ice on the IC along with some water spray.

 

These gains were noted on the WRX TMIC, STi TMIC, AND the Wair-Water IC.

[Spike1201]

thanks for the help... back to the bat cave

[4WDFrenzy]

An intercooler by itself will net you no extra horsepower on an EA82T. you have to remember, EA82Ts have small injectors(180cc) that are already running at like 85% duty cycle. The stock ECU cannot take advantage of cooler intake charge air by adding more fuel like most modern cars(ex: STi's, WRX's, Supras, Skylines, RX-7s, etc.). On modern turbo cars, the IAT signal is usually sent after air has already passed the MAF(if so equipped). I don't even think that the EA82Ts ecu can read the temperature difference after the MAF. With this being said, the ECU will not add any more fuel to compliment the cooler air that has entered the engine, so no horsepower is to be gained. Now, with a decent intercooler, you will, however, gain alot more torque on stock boost, as the air has to travel a longer distance(I.E.: fill the internal space of the intercooler) before it enters the engine. Throw some increased fuel pressure(via an aftermarket FPR and/or bigger injectors) and more boost pressure(via an MBC or EBC) into the mix with your newly mounted intercooler, and you got some extra pony power on your hands.

 

Patrick

[kiwi subbie]

im going to fit an water cooled intercooler to my xt turbo

[calebz]

WRX TMIC and TD04

[casioqv]

I don't even think that the EA82Ts ecu can read the temperature difference after the MAF.

 

The ecu doesn't need to read the temperature difference to increase the fuel flow to the engine. The flapper-type air "mass" meter measures the volume of air being sucked into the turbocharger. From this it estimates the air mass using the PV=nRT formula I gave earlier, and injects the correct amount of fuel. The ECU doesn't need to know what the intake charge temperature is to provide the correct amount of fuel, it just needs to know the mass of air so that it can maintain the correct air fuel ratio. As I explained previously, an intercooler will cause additional air mass to enter the engine at the factory boost. Before the turbo this additional mass is measured as additional airflow.

 

Where you might get into a problem is if the ECU isn't capable of measuring the increased airflow, and adjusting fuel accordingly. Some flapper type air "mass" meters do not function on wide open throttle, and the ECU just flows a set amount of fuel for each RPM based on the stock boost. This is true with the Bosch L-jetronic system, which the EA82T system seems to be based on. I'm not sure if it's the case with the EA82T.

[kingbobdole]

DORK FIGHT!!!!

 

Anyway, the fueling thing is right. I personally do not think that the ECU will add more fuel, what I think it will do is add more timing. Since the air is cooler, chances of knock are reduced. The ECU will read the knock sensor and advance the timing till it "sees" knock, then back off... A+B=the ECU will be able to run more timing and more timing has been proven to result in more power.

[casioqv]

I personally do not think that the ECU will add more fuel, what I think it will do is add more timing.

 

Why will it not add additional fuel? Please explain. If the flapper in the air "mass" meter is stuck all the way open at WOT on a stock engine, and the fuel system cannot add any additional fuel, wouldn't cooling the air charge cause the engine to run lean, and increase the chance of predetonation? I do not think that the stock fuel system is unable to adjust for varying flow rates, as that would cause very serious problems in any turbocharged engine.

 

I found an excellent article online that shows how to calculate the change in air mass due to an intercooler:

http://www.gnttype.org/techarea/turbo/turboflow.html

Please read the section on volumetric efficiency, and explain logically (in the context of the article, and my previous explanation) why you think that an intercooler would not increase the amount of air (and therefore fuel) entering the engine. The book "maximum boost" that I mentioned earlier is also an excellent source of information, and clearly explains what I am talking about. I do not think that it is possible, or safe to effectively modify a turbocharged engine for additional performance without understanding exactly what you are doing, and what the effects will be. I may be a dork, but my engines last a long time, and generate more power without blowing up. The ideas I am expressing here are not unusual or radical, they are clearly explained in every book I have ever seen regarding turbocharger system design, and can be found in any basic textbook on classical physics or engineering thermodynamics as well.

[4WDFrenzy]

The ecu doesn't need to read the temperature difference to increase the fuel flow to the engine.

 

While this may be partially true, how do you explain increased richness during a cold-idle start-up? Most cars that the ECU can adjust to difference in intake temp, will add additional fuel depending on that incoming air's temperature. That's why if you trick the ECU with one of those cheap resisitors attached to the IAT sensor, it will cause the ECU to add more fuel because the ECU doesn't think that the engine is warmed up.

 

Now, an intercooler doesn't add any more air than is already there. You have to increase the amount of air that is drawn into the engine, by cams, oversized valves, porting, bigger turbo, more boost, it is your choice. An intercooler simply cools the air and causes it to become more dense, further lowering the threshhold for detonation. Of course, like kingbobdole said, the ecu will advance the timing. The cooler the air is, the harder it is for it to get hot enough in the combustion chamber for the A/F mixture to pre-ignite. That is why when you just simply add an intercooler on stock boost on an EA82T, you don't much, if any horsepower, just torque. Now if you turn up the boost(which will draw in more air) or change your turbocharger in favor of one that flows more air, you will gain a few horsepower. But the major thing is to make sure to add more fuel to take advantage of the increased airflow. Otherwise, you can give your engine the long kiss goodnight, because it is done.

 

Patrick

[casioqv]

Now, an intercooler doesn't add any more air than is already there.

 

Did you read the entire thread? Did you read the link I posted earlier? You can't just say "it doesn't add any more air" without any explanation whatsoever, when I provided references written by well known mechanical engineers that design turbocharger systems professionally and say just the opposite.

 

While this may be partially true, how do you explain increased richness during a cold-idle start-up?

 

This effect has nothing to do with intercooling. Cold idle enrichment is to provide the proper stoichiometric air/fuel ratio at cold temperatures when the fuel condenses instead of atomizing properly. When a multi port fuel injected engine is fully warmed up, the atomization is very complete and this is a non-issue, even if the intake charge is still very cold. Again, don't take my word for it read it in the book "Bosch Fuel Injection and Engine Management" by the late Charles O. Probst, SAE.

[ausubaru92]

The ecu will inject more fuel.

 

When the air is cooled by the intercooler, it becomes more dense and thus takes up less space. This causes a pressure drop in the intake system, this simply creates a gap for the turbo to add more air. So the air flow meter will see this increased air movement and add more fuel. Up to a point of course where the injectors are at 100% duty cycle

 

Gannon