matt13b

VFAD (Variable Fresh Air Duct) removal or alternatively capping the vacuum hose to keep it open all the time?
Here is the DIY thread- https://www.rx8club.com/series-i-do-yourself-forum-73/diy-removing-vfad-148881/
I like the part halfway through where people work out you just need to cap a hose off to keep the VFAD open the whole time, therefore feeding more fresh air to the engine. It seems like a mod that has no drawbacks. Do you guys agree or am I missing something?

2SeeKU

iTrader: (1)

I can't see any draw backs. More air = more power. Especially since the 2003's (not sure if it's auto only) don't have a vfad...

Edit: Plus, the ms/aem intakes require you to remove it (plus plug the vacum line).

matt13b

I agree and was hoping there was someone in Sydney I could have help me do it. I mean just point to the right hose to cap? I can't see any drawbacks. It seems win-win. It is just to keep the car quiet at low speed by starving the engine of air..

DrewMan

I just got rid of it altogether

Odula Ram air intake

Revolver

To me this falls into the "more noise for doubtful benefit" category.

People have frigged around with intakes since the Renesis was released and I've yet to see any evidence of appreciable power gains. More air doesn't necessarily equal more power if the intake has already been optimised.

matt13b

Well it started on Sunday when a mate and I put in a second oil cooler. When we took the bumper off I was shocked to see where the factory airbox is fed from. It points sideways behind the bumper which to me seems that the air it draws would be warm engine air at best. So I thought that I may get the Odula duct to feed the box with better air at a better angle. While researching the Odula duct found people who were removing or disabling the VFAD.
I've read the pros and cons of it on a long thread and it seems that it is something that starves the engine of air in order to keep it quieter at low speeds rather than something that is there to optimise the air flow to the airbox.

Revolver

Yes, I've read the long discussions too - and my point stands. Lots of conjecture, bugger all hard evidence...but if you want to play, go for it.

ASH8

Dave is right on here, Removal of the VFAD contributes to more induction noise, and I also have not seen ANY so called HP gains or any performance gains at all.

When will guys get it through their heads that Mazda have done EVERYTHING they possibly could to get the Max power out of the Renny in NA form.

Turbo IMO is the only way to get more HP and Torque.

Revolver

Or supercharging, agreed.

I fitted a catback because the stock car sounds like a vacuum cleaner on speed and Hymee's design dissipates boot heat better but I've ignored the intake side of things on the basis that Mazda thoroughly developed the breathing of the Renesis and I don't need induction noise added to my exhaust noise. Until someone posts some reliable before and after dyno information, I'm happy to stick to that view.

But, as posted earlier, people seem to like to play with intakes as much as they like fitting after market exhausts, so who am I to spoil their fun...

rotarenvy

I'm running N/A without the v-fad at the moment. any benefit is barely noticeable. it is noisier but does sound kind of cool.
I think an odula or revi duct for cooler air would be nice and would make a noticeable difference.

2SeeKU

iTrader: (1)

Hmm, l'm not sure about power gain (I went from bone stock to an AEM). I can tell you however, an AEM adds nowhere near the same amount of power as an over the rad cai on a V8 commodore...

takahashi

matt:

https://www.rx8club.com/showthread.p...t=odula+intake

matt13b

Thanks Taka. That was actually the thread I was referring to that got me interested in the VFAD. I think I will order an Odula duct..

Revolver

Then do us all a favour Matt and organise to dyno it before and after installation (on the same day using the same dyno if poss).

Would be good to see some hard numbers instead of butt impressions...

matt13b

You guys have successfully talked me out of it, sorry! It was this link from Andrew that changed my mind finally- http://en.wikipedia.org/wiki/Variable_l ... e_manifold

takahashi

That will not give hard numbers, since there is no fan in the dyno world will generate the air you get travelling 100kmh.

Try a Gtech, Dynolicious or if you have cash - VBox Racelogic. ie on road dyno.

Revolver

Well just think Matt, with the money you've saved you can pick up a spare set of track rims...

auzoom

Matt, I still think there is benefit from extending the existing intake runs to pull cool air. I did it on my old RMagic front end and it was much snappier on the throttle.

matt13b

So you think something like the Odula duct would still be beneficial? There has to be a better way to feed the air than that tube that sucks warm air from behind the bumper surely!

auzoom

This is one way

matt13b

Interesting but very expensive looking! I'm not big on body kits actually. I tend to stick to mods that do stuff rather than look good. I like the look of some kits but prefer to spend the money in other areas. I would have already ripped it off by now as well. It's hard enough getting in and out of driveways now without a kit!

auzoom

Matt, we have debated looks v functionality already this week. The point wasn't to identify the body kit but the fact you can quite simply open up that low rpm runner to fresh air. This is one way, I have seen it done on an OEM front end and I can imagine you could do it quite ... stealthily.

Cheers

Andrew

Revolver

I've seen that before too. Before you start cutting holes in things I'd think long and hard about functionality v resale. I think most punters would run a mile from a car with that kind of mod...

auzoom

OK ... I will clarify again...I am not saying anyone should or needs to cut into anything. Having said that, how do you think the VFAD removed with a ruddy great snorkel is going to affect resale?

Matt is a creative guy, I am sure he can find a way to do it without cutting...I can think of a few.

Cheers

Andrew

Revolver

I wasn't suggesting you were advising anything Andrew - merely offering my 2 cents. And I quite agree about the ruddy great snorkel, which is why I would leave the VFAD as is unless and until someone can demonstrate that it's worth removing.

And to clarify, I'm not trying to stymie anyone's creativity - just suggesting that as the benefits are hardly mind blowing (pardon the pun), Matt might like to think twice before spending time and money on it.