Water to Air Intercooler on 4AGZE

[Mr Revhead]

a FMIC works very well when moving through cool air.

the w2a set up is more temp stable and will not suffer from heatsoak unless your coolant capacity is too low.
the reason a w2a is so popular in an MR2 is its very hard to install a decent a2a system in one, its a lot easier in a fround engined car.

what do you use your car for?

[normality78]

Well its my daily ride. Its my only car. Occasionally do have some friendly 300m drag with my friends.

my main objective is to have a constant low intake temp. as fmic do have longer pipping route vs top mount, i do believe engine bay heat does affect the intercooler pipping to become hot hence the air that travel thru does get heated up slightly even its after intercooler. This is also one of the area im looking to improve it. Well of course, by doing so i will improve my respond too.

That's makes me looking into w2a solution but as i mentioned earlier 2 point is my concern. So far i do noted mr2 and nsx benefit the most frm w2a solution due to thier engine chasis location

[motormad]

I have a Subaru Legacy water to air setup here, it should be more than enough for 200bhp as the Legacy was 280bhp twin turbo. The heat exchanger is a good size and the pump was designed to run at 40% capacity constantly and switch to 100% under boost.

[witte reus]

Well its my daily ride. Its my only car. Occasionally do have some friendly 300m drag with my friends.

my main objective is to have a constant low intake temp. as fmic do have longer pipping route vs top mount, i do believe engine bay heat does affect the intercooler pipping to become hot hence the air that travel thru does get heated up slightly even its after intercooler. This is also one of the area im looking to improve it. Well of course, by doing so i will improve my respond too.

That's makes me looking into w2a solution but as i mentioned earlier 2 point is my concern. So far i do noted mr2 and nsx benefit the most frm w2a solution due to thier engine chasis location

What do you think happens with the water in your W2A when you stand stil? It heats up And when you start driving again all those liters of water have to be colled down again .
With an A2A you only have to cool down that little piece of tube from the IC to the engine.

An W2A is only better then an A2A in those cases when you don't have enough roome for an A2A
Or if you want to cool down ALOT of air (in dragster cars)

[feral4mr2]

^^^ never heard of delayed pump cycles and fanned heat exchangers eh?......

plus the water in the core of a w2a unit gets cooled by the air being drawn through it at idle and off boost.

[motormad]

Which is why the Legacy set up pumps constantly at a lower capacity untill required + smaller area to pressurise = better throttle response. Manufacturers tend not to use them to save the pennies (cents?)

[AeRoKaBn]

completely off topic (sorry!) but didnt wanna start a poxy little thread just for this...

took my my car for a nice little spin didnt hit rev limiter but gave it a bit and when i got back noticed the hose had come off one end of the actuator on the front turbo of the 1j.

would this of done any damage? sorry again for the hijack

[normality78]

I just remember that Celica was using W2A too....

[feral4mr2]

completely off topic (sorry!) but didnt wanna start a poxy little thread just for this...

took my my car for a nice little spin didnt hit rev limiter but gave it a bit and when i got back noticed the hose had come off one end of the actuator on the front turbo of the 1j.

would this of done any damage? sorry again for the hijack

well the actuator might not of worked making the turbo boost spike to whatever, could of leaned out and popped your engine, if you had a good w2a i/c on the car the charge air temps might of not got hot enough to help cause much damage if you did have boost spike.

buy a bloody boost guage and always do a pre start. and yes, completly off topic. maybe you could buy a book or search the forum as to what the actuator does.

[witte reus]

^^^ never heard of delayed pump cycles and fanned heat exchangers eh?......

plus the water in the core of a w2a unit gets cooled by the air being drawn through it at idle and off boost.

You can "delay" and "fan" as much as yoo want, but the heat generated by the engine(radiated heat) is always more then the air drawn through it by the engine running idle can cool down

Okay, the inside surface area of the W2A inside is alot bigger then the outside surface but on the other hand the air in an A2A unit will also cool the tube from the IC to the engine.

My point is that with an W2A you are cooling water with outside air and with this water you want to cool the charge air.
An A2A cooler uses directly the outside air to cool the charged air, which is always more efficient(not even taking into account the electric pump and weight of the water ), and isn't that what everything in tuning is abouth; effiecientcy

[feral4mr2]

oh i'm sure a good sized a2a unit in a front engined car would be very effecient and ideal. please excuse me, i keep subconciosly referring to vehicles such as a mr2 in my w2a mentality.

[AeRoKaBn]

lol, thanks feral4mr2 yes i should of searched i usually do... i know they open the waste gate once they reach a certain set psi (i think) but yeah just wanted to hear from someone who actually knows.. cheers again

[witte reus]

oh i'm sure a good sized a2a unit in a front engined car would be very effecient and ideal. please excuse me, i keep subconciosly referring to vehicles such as a mr2 in my w2a mentality.

In a car with the engine in the back is the W2A ideal! Because of the simple fact that for an A2A is no rome.

But my point is that an A2A efficienter is in the way it uses the outside air and it has less weight

[Pube]

Im using a factory w2a setup on my 1GGTE. Im using a davies craig booster pump, PWR 16" heat exchanger and fan, and a water reservior of around 10L. I have found with constant air flow, the cooler stays very cool even though it is sitting right on top of the engine. However, as soon as there is no air flow it does get heat soak. I have a thermal blanket sitting between the cooler and the engine. I find it works pretty well but I havent got to test it out in summer heat yet. The water in the reservior stays under room temp and the distance from the turbos to the throttle body is under half a meter. Check out my members ride for some pics.

[TERRA Operative]

On a road car, the A2A intercooler is only really acting as a large heatsink. Most of the time you simply aren't travelling fast enough for long enough to create a true heat-exchange system.
In a W2A setup, the massive heat capacity of the water absorbs the theat from the air untill equillibrium is reached and charge temps = water temp. The radiator on the W2A setup is to prevent equlibrium being reached by cooling the water.
The draw back is when you are not putting heat into the intercooler, the intercooler is putting heat into your intake. So your off-boost temps will rise.

In short, in two otherwise equal systems, a W2A system is superior for short sprints, due to the massive heat capacity of the water. But falls over during extended use as the water will reach its 'heat absorbing capacity'. Also, for screw type chargers etc. there will be heat produced even on idle, so this must be accounted for. Although with a clutch, we don't have to worry about that.

An A2A intercooler is better for extended high speed use, as there is an infinite supply of cool fresh air for heat transfer to take place. However, for short runs, the mass of the metal is more important (to act as a heatsink) than cooling air flow capacity, as there simply won't be enough flow during a sprint to create the heat-exchange.

Of course there are exceptions to this rough rule of thumb, weight versus space etc. But they both can be very effective when set up correctly.