CapitalF wrote:This is a question for Danny - forum name ORX626 I think. He works in this area I believe.
Where are you Danny?
Peter
I'm here Peter!
Well this is third go at writing this post!
Each time I started writing a thesis and tried to answer every potential question relating to intercooling. So I thought I'd try this approach instead; by making some basic generalised statements and fielding questions from there (if any).
Statement 1 - There is no easy way to select an intercooler's physical size that will provide the optimal (better than just better) performance for $ spent without considering your engine set-up and making a decision on the primary application of your vehicle. Say you went and fitted a Skyline GTR A2A IC on your B6T powered NA6, this doesn't mean that you will have achieved optimal performance (I know you can't physically fit it, but that's beside the point). More than likely you'll have increased your lag and substantially reduced the efficiency of your engine cooling system by blocking the ambient airflow to the radiator.
Statement 2 - With regards to your vehicle's application and which IC will provide optimal performance (ignoring the cost aspect) I recommend the A2A for all circuit racers (more than 50% of its life on the track) and A2W for street cars (less than 50% of its life on the track). Drag vehicles or dyno queens on pump gas (not methanol) are another kettle of fish, where one can use combinations of A2A and A2W with fun things like ice and even dry ice.
Statement 3 - For a particular engine setup, an A2A IC in 99% of cases will be cheaper than an A2W IC designed to suit that same engine setup and provide equivalent steady-state performance at the maximum duty cycle. ie. they have the ability to remove the same amount of heat from the intake charge and dissipate it to ambient.
But street cars don't spend a whole lot of time at maximum duty cycle....this is where A2W comes to the fore...refer to Autospeed article - 'Thermal Mass'.
Statement 4 - The transient performance of an A2A intercooler is more sensitive to the vehicle's road speed than an A2W intercooler. ie. A2W IC's are more efficient at removing heat from the engine intake charge at low vehicle speeds than A2A for longer periods (Thermal mass once again).
Statement 5 - When both are designed, an A2A IC will always be more efficient at it's maximum duty cycle than the 'equivalent' A2W IC. This is because heat has to transfer across two fluids (air to water, then to air again) versus one fluid for A2A IC's (air to air). Everytime heat transfers from one fluid to another the efficiency of the transfer is reduced because the temperature differential (delta T) is less.
Statement 6 - Does all of the above really matter? It all depends on whether it matters to you and how big your budget is and whether you can physically fit the IC type you want (this is the most common problem when trying to design A2W IC's). Most of the time if an intercooler looks about right it will probably provide an improvement in performance. It's just whether or not you want to know what sort of improvement you will get before you spend your hard-earned cash and have decided how many ponies you are chasing.
I hope this helps and doesn't confuse the situation. Aluminium Engineering and Radiators (ARE) provide the service of designing IC's for specific engine set-ups and their specific applications. I'm not financially associated with them but have provided professional engineering assistance to them for the past 8 years. They have also designed tube extrusions for particular applications - optimised cross-sectional area to surface area ratios. If you do want the optimal in IC performance, give Richard a call on (07) 3205 4620.
Cheers,
Danny
I've done this on my car and thought it was an urban myth, but it dropped the intake temps by a couple of degrees!
