924Board.org

[Rick MacLaren]

Anyone ever put a second intercooler on a 924 Turbo? Would it be worth it if the restriction could be reduced to nil?

[Cbass]

Where could you put it? My understanding is it's more efficient to have one big intercooler, unless you are running twin turbos. Even then, most people use a single IC.

[Rick MacLaren]

Yeah, I know that the big IC is optimum, but what about two? One top mounted and one front mounted? Will such cooling be advantageous for our turbos? Or will we need a bigger turbo?

[Peter_in_AU]

I've seen pics of it done before (not on a 924). The guy used two saab intercoolers which are very deep and have a small frontal area. I think the reason he used two was he didn't want to hack the bodywork to fit one large 'cooler.

With all the space in the nose of a 924 after you rip out the aircon you can fit a really good sized intercooler up front.

I suppose it comes down to pressure drop across the intercooler(s). If two small ones are dropping more pressure than one big one and you have the space then bigger is better. Then again with the marginal cooling of the standard radiator you might need to invest in a more efficient radiator if you filled all the space in front of it with one big intercooler

[Rick MacLaren]

Thanks Peter.

Yes well I like the top mounted one from John, but I saw a 944 here with two and wondered how that setup would compare to one big one. I think maybe the 944 guy I saw was really cranking the boost. But thanks for alterting me to the pressure drop idea...that would be a big issue. Also with two I spose you increase the odds of leakage.

[larso]

I think two might be a good idea or maybe even two rads, because I notice a difference when I put my interior heat on, the heater core actually has an effect. Heater core is pretty small to make a difference, so maybe two is a lot better than one?

[John H]

Normally you onl;y run two inter coolers if you're run two turbos, like the tractor pulling guys.

What they do is have sequetial turbos the first turbo is mapped to provide a certain amount of air the engine needs then this goes through the intercooler the pressure drop calculate and the next turbo installed to take this air flow and increase teh boost and volume to what he engine requires and this then flows through the next intercooler.
The early Nissan Skylines had sequential turbos but only one intercooler.
Main problem using two intercoolers as Peter mentioned is pressure drop. If you get enough air flow over a unit then there shoudl eb no real reason for two.
What you need for an efficent intercooler is good flow over the unit, good air flow through it and then a good heat sink factor. If you look atthe construction of any of the racing inter cooler syou'll see they hav eloss restriction internally and also relatively heavy constructio nto allow for good heat transfer.