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HKC Speed Hood scoop Benefit?


dahoseman

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I'm curious if anyone has installed the HKC Speed hood scoop or something similar like the RRev? Specifically, I'd like to know if there is any verifiable benefit .... emphasis on verifiable. When it comes to my daily drivers, functionality is my only real concern and I could scarcely care less about what things look like. I'm considering installing the bigger hood scoop to potentially pass more air over the intercooler.

 

Aerodynamics isn't always as simple as making a bigger part, so I'm curious to see if anyone has any verified numbers to show an actual difference? (cfm difference through the scoop at standard mounting angle, intake temperature difference from stock, whp difference from stock)

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Pretty sure you wont find anything verifiable.

 

For the increase in the size of the hood scoop to have much of an effect the stock hood scoop would have to be poorly sized. I'm sure Subaru put a lot of work into sizing the intercooler and hood scoop to do more than the necessary work required.

 

I'm a process engineer and know a bit about heat exchangers. The largest factors in altering the efficiency of a heat exchanger (without changing the design) is altering the temperature differential (temp of cold air coming in vs. temp of hot air inside the intercooler) and altering the velocity of the cooling medium.

A slightly larger opening might (very) slightly increase the pressure or the cooling air but this will be negligible.

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  • 2 months later...
Pretty sure you wont find anything verifiable.

 

For the increase in the size of the hood scoop to have much of an effect the stock hood scoop would have to be poorly sized. I'm sure Subaru put a lot of work into sizing the intercooler and hood scoop to do more than the necessary work required.

 

I'm a process engineer and know a bit about heat exchangers. The largest factors in altering the efficiency of a heat exchanger (without changing the design) is altering the temperature differential (temp of cold air coming in vs. temp of hot air inside the intercooler) and altering the velocity of the cooling medium.

A slightly larger opening might (very) slightly increase the pressure or the cooling air but this will be negligible.

 

I figured it wouldn't have much of a benefit, but I was curious.

If the gains are negligible, why to STi's and WRX's have considerably larger openings?

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the rrev lip for our scoop only changes the initial opening size, not the entire scoop size. The STi scoop is large all the way, not constricted. If large all the way, it does make a difference.

 

Yup. The existing hole is your limiting factor. On the WRX/STi, the whole scoop is a separate piece from the hood, thus they're able to make the inlet tract(and overall volume) much larger, easily. Something effective on our Legacies would require cutting the hood.

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