Worth going with external wastegate on 14b?

[Kevin Jewer]

I'm not sure which I need more of to pull it off, to be honest

[dislclaimer] Which reminds me, try that at your own risk! It works for me, but that doesn't make it a good idea. [/disclaimer]

 

[brute]

Unless you're trying to do something like put ice on the intercooler, spraying the fins, or anything like that, you can't achieve 100% or more efficiency. Intercoolers are considered very efficient right around 90%. Usually, however, the aftermarket ones the reputable vendors on here sell are usually at about 80%. This is why I used 80% in my example.

Compressors are even lower. Depending on altitude, boost, pressure drop, etc., compressors can operate in a myriad of efficiencies, but generally you want it operating in the highest efficiency island on the compressor map. Depending on what compressor it is, its highest efficiency will be about 72-76%. This will be explained in detail by the second quote further down.

I'm not disagreeing that you can run as much boost as you want on a 14b, I'm simply stating that it's creating a detriment to everything else on the car. The compressor is creating a lot of extra heat. Sure your intercooler will cool that down, but if it's entering the intercooler at a colder temperature, it's going to exit at a lower temperature.

Faster rotation generally means more air flow. However, air flow does not appreciably increase after the outer tips of the compressor wheel are moving faster than the speed of sound. When the air flow reaches sonic speeds, the diffuser becomes choked and only very small increases in flow rate are possible even with large increases in wheel speed.

I'm sure you already knew this, but I'm throwing it out there for the newbies reading:

Turbochargers compress the air by increasing the velocity of the air molecules on the compressor wheel and then decreasing the velocity in the diffuser section. When the air molecules do not move in a direction toward the discharge opening, they serve only to heat the air. The more the air is heated above that predicted by adiabatic compression, then the less efficient the compressor is. How well the compressor achieves pure adiabatic compression is called the adiabatic pumping efficiency.

 

[Steve93Talon]

Steve, I am familiar with air-liquid ICs, and I'm a big fan of them! For race cars anyway. A nice PWR unit almost made it's way into my 90 talon. The project goodwill car is nasty, and Joe is one of the coolest guys I've ever met.

That's the myth that bothers me the most. Water/air cools at least as well as a "race" FMIC on the street, with zero overheating issues, shorter piping, and less pressure drop through the core. Give it a try, you'll be impressed.

 

[DSM90AWD]

pfft: http://homepage.mac.com/stevestrzem...ctures/2003-04-27 19.02.05 -0700/PC010051.jpg

63F charge temp on 90+ degree day

How do ya think Goodwill went 10s on a 14b?

Still not 100% Efficient

Just poking around Spearco's Site and they tested their 2-230 core (flows to 1500cfm < 1psi drop) at a charge air temp of 400F (simulating 30psi boost) and the core cooled:
- 700CFM 90% efficiently when the water was 45F
- 1100CFM 81.5% efficiently when the water was 45F
- 1500CFM 74% efficiently when the water was 45F

The efficiency stays nearly the same with the water at 100F.

The only limitations (that I know) are the added weight, cost (yes a budget version could likely be made), additional complexity and not well suited for road racing where there is little time spent off-boost.

On the positive side, you can get cooling up to 90% of the water temps, can greatly reduce pressure loss due to the higher flow core / less piping, and face it, it just looks soo cool

Then again, Meth Injection combined with a high flowing Top/Bottom core (what I'm workign on) may just get you to the same point

Yea maybe we should start a new thread

 

[Steve93Talon]

63F charge temps on a 90F day is more than 100% IC efficiency. I've seen it firsthand. Obviously, it wouldn't work on a road racing car, but on the street after repeated pulls with ambient water in the tank, the temps never get more than 10-15F over ambient. I'd imagine even a large FMIC would start to heat soak sooner than 5 gallons of water (remember that the water is also passing through a heat exchanger which brings it back down near ambient).

I've got a charge temp probe before and after my meth injection nozzle, and other than an immediate drop when I first hit enough boost to activate the sprayer, I notice no difference in charge temps. There are already plenty of threads on this, sorry to keep this one off topic, just responding to other posts.

 

[DSM90AWD]

63F charge temps on a 90F day is more than 100% IC efficiency.

Efficiency of an intercooler core is related to the charge air temp drop w.r.t. temp of the cooling medium (water in an Air/Water) not the ambient air. Efficiency of the intercooler itself does so can

Some other interesting insights from Corky Bell's Website (since we are so wayy off topic anyhow):

How can an air-to-air intercooler be more efficient than a water based intercooler?
There is an overwhelming quantity of ambient air available to cool an air-to-air core relative to the charge air thru the inside of the intercooler (The iced down water intercooler is the only exception to this argument.). At just 60 mph, with a 300 bhp engine at full tilt, the ambient air available to cool the intercooler is about ten times the amount of charge air needed to make the 300 hp. Whereas the water intercooler largely stores the heat in the water until off throttle allows a reverse exchange. Some heat is expelled from a front water cooler, but the temperature difference between the water and ambient air is not large enough to drive out much heat. Another way to view the situation is that ultimately the heat removed from the air charge must go into the atmosphere regardless of whether it's from an air intercooler or a water based intercooler. The problem with the water intercooler is that the heat has more barriers to cross to reach the atmosphere than the air intercooler. Like it or not, each barrier represents a resistance to the transfer of heat. The net result; more barriers, less heat transfer.

What are the relative merits of an air or water-cooled intercooler and which would suit my purposes best?
This depends on the circumstances. These circumstances are; street use, drag racing, or endurance racing (more than two minutes).

Street use: The air-to-air intercooler will prove superior in efficiency when sized properly.

Drag racing: The short spurt of power allows the iced water to cool the charge air to below ambient temperature.

Endurance racing: The air-to-air intercooler is clearly superior due to the shorter route of getting the heat out of the air charge and into the atmosphere. Endurance racing would preclude the use of ice water, thus negating the singular advantage of the water intercooler. Further, the air-to-air intercooler is (virtually, see comments below) maintenance free

Interesting to note that the top DSM/EVO Drag racers (Shep, Buschur, AMS, Magnus, Showdown) are using Air/Air, Meth Injection or a combination. If Air/Water was a better system, I wonder why they are not using it Then again a nitrous/meth backfire thru an Air/Water core would probably be real bad.

 

[Kevin Jewer]

I'm not disagreeing that you can run as much boost as you want on a 14b, I'm simply stating that it's creating a detriment to everything else on the car. The compressor is creating a lot of extra heat. Sure your intercooler will cool that down, but if it's entering the intercooler at a colder temperature, it's going to exit at a lower temperature.

But my point remains. If the heat goes up, but you still set records or personal bests, does it really matter? Nope. Obviously I'm still implying race gas use, but anyone that maxes out any turbo on pump gas deserves what they get.

I do know that liquid ICs work well on street cars too, believe me. But my personal preference is to keep things simple for mostly street type cars. If I was going to run one on the street I would run a heat exchanger up front to keep the water cool. It may take a long time to heat soak, but it will take much longer to un-heatsoak without one An ex-gf of mine ran one on a vortech supercharged civic si that was putting down some impressive HP for its time (~5 years ago), and it worked very well. But I have to appreciate the simplicity of a regular old FMIC.

And obviously air-liquid ICs are not over 100% efficient, but when you consider that IATs are always referenced to ambient air (to compare to what NAs have to work with), it's common practice to think of air-liqid ICs in the same terms, even though it may be incorrect.