View Full Version : WoW! What a difference cold air induction made!

05-16-2006, 10:21 PM
Last fall, on my one pass at the drag strip. My intake temps with my intercooled twin turbo motor got to 138 degrees! :eek: I was taking in hot engine compartment air.
I now have a ram air induction routing cold air from outside the engine bay. I data logged a full pass on the street and it was under 100 degrees!! I actually had to richen up WOT under full boost to compensate for the colder air. Just thought I would share this huge increase in power. What a difference! :D

05-16-2006, 10:50 PM
Sub-100 degree air under full boost? It gets hotter than that OUTSIDE here during the summer! :rofl:

I wish my IAT's were that cold. Guess I need to get off my ass and design an intercooler. I usually see 135-145F under full boost even with the water injection...which leads me to my next question. What core size did you use for your intercooler? I'm just doing the preliminary measurements, design, and information gathering right now.

05-17-2006, 04:22 PM
I use a Spearco core. If I remember correctly, the core measures 3.5 x 15 x 20.

05-17-2006, 06:27 PM
I use a Spearco core. If I remember correctly, the core measures 3.5 x 15 x 20.

Have you ever compared inlet vs. discharge air temps, and what's the pressure drop?

Reason why I ask is I'll probably be fabbing something nearly identical for my car; I came up with almost identical measurements of my front end. Trying to get an idea of what results I can expect in the "real world."

I know the side tank configuration (with the charge air taking the long way through the core) isn't the most idea from a pressure drop standpoint but it's the best way to fit it in the noses of our cars.


05-17-2006, 07:36 PM
Troy -
If you need good intercooler info, email or call Tim at Ron Davis radiators. Also, remember for every 10 degree drop in inlet temperature you pick up approximately 1%. So if you drop 40 degrees on a 600 hp engine, you get a "free" 24 hp. It's a good deal.

05-17-2006, 07:37 PM
Nitro -
"Free" horsepower is always a good thing... :)

05-17-2006, 08:07 PM
I think my Spearco core is rated at 1500 cfm and a .5psi drop at 15 psi. Supposed to be about the best on the market. Keep in mind though. For a street car that drives at low speeds in traffic, a longer core is optimal because it allows more time for the air to cool. A short wider cooler flows more air, but allows less time for the air to be cooled. This is not good when you have a very minimal airflow speed through the fins.

I am making between 900-1000 hp, so every 1% in hp increase really adds up! :unibrow: :eek:

05-18-2006, 10:51 AM
Good to know, I didn't think about the longer core from that standpoint. I was looking at Bell Intercooler's website for core dimensions/flow data, guess I'll look at Spearco too.

Once I get a core size and tank design finalized Ron Davis will probably be getting the call to fab it as my aluminum welding skills are terrible.

The next thing I'm wondering about is where to put my surge valve. The ideal location would be just prior to the restriction (i.e. throttle body) to minimize backflow through the intercooler when I let off the throttle but I think that putting it between the supercharger dischrage and the intercooler inlet would be the ideal spot-- because when idling or creeping along the supercharger isn't constantly blowing a large volume of warm air through the intercooler and heatsoaking it.

Last favor to ask-- think you could take some pictures of how you fit your intercooler and piping around the factory radiator support? I have some ideas of my own but would like to see how you tackled the problem.

05-18-2006, 12:27 PM
Here's a picture of Jody's intercooler mount around the radiator. Nice mount.

A couple of things to think about - Putting the surge valve close to the blower won't fix any heat soak problem. The air goes throught the blower all the time. The surge valve is only for pressure imbalance on throttle bore shutoff. It is always closed under normal running conditions. Also, one of the reasons for putting it close to the throttle bores is to keep the airflow moving through the piping just like a return line on a high hp fuel system.

There are pros and cons to everything...

05-18-2006, 02:52 PM
The surge valve is only for pressure imbalance on throttle bore shutoff. It is always closed under normal running conditions.

True with a turbo but not so on a centrifugal supercharger... the surge valve is nearly always open until you get into the throttle enough so it closes. This is so the air moved by the constantly spinning supercharger gets "dumped overboard" which takes the load off the SC during cruise. It closes only when you step into it and vacuum drops enough for the internal spring to close it which allows it to build boost. The surge valve in a supercharged application is totally different from a turbo applications blowoff valve (which as you said is normally closed until one lets of the throttle under boost, which opens it to prevent compressor surge.)

My thinking was given my centrifugal application it would be best to keep the amount of air moving through the IC at a minimum during cruise conditions by putting the surge valve between the supercharger and intercooler; this would allow the IC to become as cold as possible. The only bad thing is that the valve would be placed on the "wrong side" of the restriction (throttle body) so when I snap off the throttle from a boost condition a good amount of the pressurized air would have to turn around and go back through the IC and out the surge valve.

It's probably not a big deal at all to put the surge valve just prior to the throttle body; if the IC is sized right it would be more than adequate to cool the non-pressurized airflow that will be constantly moving through it at cruise conditions with the surge valve open.

This will be a fun install... slice the radiator support, scoot the radiator back about 3", relocate my AC condensor rearwards to match (and redo the hoses to remote mount the receiver/dryer), try to fit the IC around the hood latch (or ditch it completely and run pins or those Aerocatch latches), and finally I'll need to squeeze in 3 coolers for oil, power steering, and fuel.