Air to air intercooler efficiency for a given intercooler varies with two different factors:
1. the amount of air to be cooled
2. the amount of cooling air going across the core
If Jacks IC isnt working on a couple of cars then both the cars and the IC's themselfs need looked at:
Laz stated good inlet temps with this IC on a low 9 second car. That should proove the IC is good into the HP range Ted and Otto are at. Atleast good enough not to have the inlet temps thier seeing. I don't think anyone posting or reading this thread would think those temps are anything less than INSANELY high. Air inlet path and turbo selection will effect the overall outlet temps of the IC, but a good IC will mask this some what anyway. Turbo out temps 50 deg higher doesn't mean IC out temps will be 50 deg higher, they will only be 5, 10, 15 deg higher, it all depends on the efficiency of the IC. The physical size of the Cotton FM should allow it to be efficient at the 9 second power level and Laz's inlet temps prove it. The only question left is wether Laz is doing some thing to get a crazy amount of cooling air across the core, or is thier something in Ted's or Otto's set up thats restricting it. This is an area that should be looked at for us all. People who are currently or planning on running a Cotton FM will want to know what to watch for, and the people switching from it and moving onto a new one will want to pay attention because it will effect thier new IC also. It would be real helpful if we could get Laz, Otto, and Ted to answere these questions that I can think of:
1. what brand and size radiator
2. what brand and size cooling fan set up
3. fan shroud set up
4. a/c condensor or not
5. any special IC scoop or airflow deflectors
6. method of cleaning the IC core and last time it was cleaned
7. whats the gap spacing between the IC and the radiator
These are a few things that I can think of the will effect the IC efficiency at the general HP level these three are at. Guys with 10 second TSM cars will not apply to this. This IC will ALWAYS be at a higher efficiency level on 10 second car than it will be on a 9 second car for a given amount of cooling air flow. Its not a bash to 10 second cars is just a law of thermal dynamics.
Ted and Otto:
A 76 turbo's peak efficiency island is below 22.5#'s of boost and below around 650hp. It has a pretty good compressor efficiency all the way up to about 32#'s and approx 800hp. It has a decent efficieny up to about 39#'s and approx 850 hp. This easily shows why a V8 guy would say that they suck at high boost, where as a V6 guy may say it did fine. The V8 guys will have to keep the boost moderate. If the V8 starts turning up the boost, the HP level will climb to high, and the 76 compressor will get real inefficient trying to pump that much air at that higher boost. Turbos should not be selected for a HP level or a boost level. The proper way to select a turbo is to determine how much HP you're going to make AT a selected boost level.
If you guys are at 27 psi and over about 750 or 800 hp at that boost level then the 76 isn't working at a high efficiency. Ted's turbo test measured after the IC. Even it Ted would have measured at the turbo outlet there would not have been a big temp difference unless he's a good bit over 800 hp. Its getting late so I'm to tired to do the math right now. If ether of you had a real good guess of what HP level you're at I could do the compressor efficiency calculations for you. Also keep in mind that if you get your IC outlet temps inline the compressor section will have to pump even more air at the 27#'s. That can be calculated also if you're curious.
Jason
