Devil Dog

The C5 Vortech kit comes with the aftercooler included.

STAGED

Despite ATI's correct claim about OVERALL efficiency of the air-air units over air-water units, they omit some major details. #1: air-air units really necessitate proper placement of the charge air cooler for maximum performance (best of course is front mount). However bring the charge air to the front-mount IC means a long and meandering path (read higher pressure drop). This means the blower has to spin faster for given mass air flow. Spinning faster in turn means more parastic losses/cylinder pressure tax for given net brake hp and hotter IC-in charge air temps that slightly offset the overall gains in charge air cooling. #2: Water can sap heat out tremendously, so a smaller charge air-water cooler is necessary ***smaller pressure drop*** for given heat removal requirements.

Analogy: put your arm out in 40 deg. F air and put your arm into 40 deg. F water and see which sucks heat out faster. The thermal boundary layer (one point of view with this is it's an insulating layer) around water is far thinner than it is for air. Thinner boundary layers --> higher temperature gradients --> and since temp. gradients drive heat transfer --> higher heat transfer rate. So while air-air units are better in efficiency, chances are that efficiency is offset by with higher inlet IC temps because of the need to spin it faster and associated with more parastic losses (bigger tax on cylinder pressure). On air-water-air units, since ambient heat sinking is done remotely to the charge air path, one can shorten the charge air path to the throttle body.

All the above reasons are why nearly all OEM S/C applications are air-water-air units (in some cases like S/Cs sandwiched on top of a manifold it's impossible to go air-air). However, as I mentioned before, air-air units have big practical advantages. Aftermarket generally can't match OEM in quality control (for the given $ spent) so minimizing complexity is a boon as an air-air unit is elegantly simple. Secondly, since air-water-air units ultimately dump heat to the surrounding air, much of the initial heat removal comes from the awesome heat capacity of the stored/circulating water and not the heat ultimately removed to the ambient; and so it's best for street applications and not road racing.

Clearly my post here is neutral and objective. And like the pressure drop vs. heat transfer tradeoff in heat transfer systems I've experimented with, supercharger systems have pros/cons so the aftercooling approaches should be considered and matched with your intended use before deciding on a kit.



[Modified by STAGED, 5:12 PM 8/3/2003]

MelloYellow

I agree that Air to Water transfers heat out faster.
For sustained use, say CONTINUOUS SC at 100% WOT/High RPM the Water Reservoir will heat up after 10 minutes constant use.

In real life street driving you will never see this continuous use. On the track it could be a problem. I'm not talking 10 minutes driving, but 10 minutes at full WOT+.

QuickSilver2002

You guys are missing the practical side of the discussion. Surface area is the number 1 practical factor in determining efficiency of heat transfer. It's very easy to put on a big air to air. It's very difficult to implement a large surface area air to water.

Packaging and simplicity is the key here. I'm sure you can make air to water more efficient, but air to air makes more sense when cost and packaging is put into the equation.

STAGED

Actually the water's ability to sink large amounts of the heat from the air for a given amount of time is why you don't need a large charge (and hence smaller surface area) air-water heat exchange unit. A unit volume of water can hold a lot more heat than the unit volume of charge air. That's why the charge air to water heat exchanger (portion of the air-water-air system) looks so nice a tidy. In fact the packaging aspect is generally the reason why OEMs choose air-water-air charge air cooling for much belt-driven supercharging applications to reduce the size of the charge cooling mechanical overhead. Conceivably, one can put the water-charger air cooler within inches of the blower discharge and also within inches of the throttle body (for a blow-thru unit) and on a positive displacement setup, have it stacked between the manifold and blower with "zero" charge air cooler plumbing (not including the water circuit)

In air-air units, you're taking the charge air to a location where it's exposed to strong cooling crossflow; the long meandering path will have direct consequences on belt driven S/C and amplify the bane of belt-driven S/C's, parastic losses. With air-water-air units, you BRING the COOL MEDIA (thereby minimizing magnitude of the parastic loss gremelin) to the charge air (more or less) and then whatever heat you pick up, you dump in a very space efficient manner.

When you throw water or liquids into the cooling equation, you're talking about much higher rate of heat dissipation densities (allowing for much lower surface areas for requisite heat removal rate). As I best recall, and for further illustrating, microchannel heat exchangers (used for electronic cooling) using air exclusively have "Watt densities" of 30 W/cm^2. Microchannels using liquid cooling have 100 W/cm^2 densities. So we're talking ~3 times the performance for equiv. area or 1/3rd the area for given heat removal requirement when using water over air only. Packaging is THE major/pivotal reason for bringing in various forms of two-phase (vs. single phase air only) heat transfer all high demand applications. Liquid cooling is what's allowing smaller more powerful chips to exist.

Your simplicity reasoning however is completely on the money for going with air-air units. :flag And reliability conscious OEMs do use this on turbocharged cars. But for belt-driven S/Cs, the issues discussed definitely make charge air-water-ambient air cooling viable and based on the # of OEM belt-driven S/C'd with air-water-air intercooling, possibly advantageous for all but the most extreme driving modes.

Stil, my discussion however, has little bearing in the overall satisfaction, as there are plenty of happy ATI-C5 and Vortech-C5 guys.


[Modified by STAGED, 8:56 PM 8/3/2003]

kromberg

Does the ATI unit require the second air bridge over the radiator as all the pics I have seen of the setup?

Keith

QuickSilver2002

Depends, the stock ati kit does not require it. It has the air filter integrated into the fan shroud behind the radiator, which really sucks (can you say heat soak).

The modified kits require you to lower the radiator so that a bridge can hook up directly to the blower inlet. This also allows you to keep the stock dual fans and avoid installing the ATI single fan shroud.

0opticZ06

Brent I have a forged bottom end and 9 psi of boost,ATI stock cam and 10's were easy on DR's smacking the rpm limiter/????????????????? :confused:

93Polo

Bruce the after cooler is standard on the C5 kit.

2003 Z06 SC

I'm new to this forum and it is nice to see alot of other procharged cars. :)
I just had my procharger installed with tpis longtube headers, thats it! I dynoed the car at 580 at the wheels with more power to go! I highly recommend a procharger. :auto:

Racer

Good numbers. What kind and year vette? How many PSI of boost? Dyno graph? :cheers:

2003 Z06 SC

My car is a 2003 and I'm running 6 psi. It is the D1SC model with 42 # injectors. KDK Performance in orlando did the install for me, thay did a good job on my GN too! They told me I could sqeeze some more out of it if I want too, but I may leave it this way for a little while. I'm not sure how to add pictures yet but when I figure it out I will post a dyno sheet and pic.s of my car. I did take the car to the track since I only live 10 min. away from it. I ran 11.7 on stock tires at 124 mph. and track officials told me to slow down till I get roll bar. I hate it when they do that. :cry

bkuklin

where is the best place to pick up an ATI system?
How long did it actually take you to install and what issue did you run into? Thanks... :steering: