I've posted this before, but here is the reply from Jim Mederer, Racing Beat's co-founder and chief engineer, when I e-mailed RB and asked them about adequate airflow when using the "duct". His reply is as follows:

"I did consider the frontal areas available when designing the ram air duct for the RX8:

Open area of "grille" 37 square inches
Open area of lower mouth opening 120 square inches
Projected frontal area of radiator 360 square inches

The classic design criteria for a duct leading to a radiator is "1 to 3", that is, the duct can be one third the area of the radiator and not restrict cooling. As the numbers above show, the front of the RX8 satisfies this requirement even if the 37 square inches of grille area are dedicated to engine ram air. Two other factors have a bearing on this analysis: the stock radiator of the RX8 has a VERY fine fin design which reduces air flow - and puts a premium on sealing the air ahead of the radiator to maximumize the pressure of the air to improve cooling; second, the underside of the ram air duct is a curved shape that directs air into the radiator more smoothly. To sum up, there is still plenty of air to cool the radiator when using the ram air duct, and it is well-directed to do the job."


Hope this helps. I love my combo of REVi intake and Duct!

Does anyone that own the REVi have comments about water ingestion? It seems to be mounted fairly low...

the bottom of the duct has holes for water to escape, it's also shaped so that heavier (than air) stuff would get trapped there instead of going up. It's also not that low - it fits in the bottom of the black honey comb area of the stock grill.

I went through the wettest Winter yet in the Pacific Northwest - out on the Coast. REVi and Duct work fine in the heavy rain.

Now does the duct work in conjunction with the Revi intake only or can it be used with the Stock air box as well. ??

any intake bro...

Ive been wanting to install the RB duct for a while on my modded stock airbox, but Im worried about taking on water (I live in tropical storm world). Can anyone comment on the dangers of running the ram air duct and taking water in the intake???
If its not an issue, Ill order the duct next week :)

also think just installing the duct on the stock intake will coz any performance gains?

Also
Can you upload a pic of your modded stock intake..mmm just curious :D

i always heard that it's pretty tough to hydrolock a rotary. but, i do live in miami & have sucked in water during floods in previous cars.
anyways, the rb duct sits pretty high up on the bumper & has holes on the bottom side to release water that may get sucked in... i think it'll be fine. i'm planning on getting one for sure.

dgrx8: That sounds good to me... I was told it almost impossible to hydrolock a rotory, but my brother killed his Jetta in hurricane Katrina last summer, and ever since Ive been very scared of CAI in Miami. I wasnt aware there were hole in the bottom of the duct, that is very reassuring... seeing as how water is heavier than air is should drop right out before getting sucked in. Thanks for the info man.

Unhooked: Pictures wont really show much. Ive simply gutted the stock airbox (took out the trumpet and dividers) disabled the VFAD, put in a K&N drop-in filter and dremmeled the inside of the box to a smooth. Youd be suprised how much better the air flows without all of thoes rivets inside. Took me about 2 hours to do and Id say my stock intake is now just as good as a Revi, minus the ram-air duct, of course.

no problem...
if it makes you feel any better, you could fit an AEM bypass valve on any intake. this will def prevent any water suckage...

again, good to know... thanks for the wealth of info.

Do Revi intake kit & ram air duct fit 2006 RX-8?
Thanks.

Ram air effect does not kick in any observable fashion until over 100mph, and it is not a significant factor until well beyond that speed.

That is not to say that moving the air intake never helps. If it's located in a bad spot to start with (like a flat surface that Bernoulli says will create a low pressure area) then you may wind up with negative pressure in the plenum. But if it's in a shielded area of normal atmospheric pressure you probably won't gain anything (and might hurt) by opening a duct forward.

All of that has nothing to do with cold air in vs hot engine bay air.

Pilgrim

yes, it fits all rx-8's.