Mazda Rotary Club

Hi there,

Any thoughts on the air intake on the 99 spec front bumpers?

Fitting my front number plate, it is apparent that it sits directly over the air intake! There is still room behind the plate, maybe an inch gap, but this is obviously a significant barrier to taking in air! I guess it may even be deflecting the air flow away from the intake!

Anyone with this front end ever thought about this? I think I am correct in saying that the air intake is in the number plate slot and not scooping air from the radiator hole.  (I presume Japanese plates are small and thinner, and not the chunky square things the UK has to have, so do not obstruct the opening).

Thoughs/solutions/corrections??

Cheers,

Andrew

Piccy to maybe help explain what I\'m on about!

Take the front plate off and stick it in your front window , if you get pulled you put it back on , then you take it off the day after or just blag your way , "its a jap car they dont have front number plate mounts" ;)

surely it would look a bit strange thou as there would just be a square thing with holes in it right at the front which is fairly obviously (hopefully not for "traffic" with above plan ) & dunno how it\'d keep with the lines if the 7.............(http://instagiber.net/smiliesdotcom/ups/majs/confused.gif)
Si

Do\'h my bad forgot this is the late spec bumper , as the older ones have the metal frame that you just unbolt and its gone :p

I managed to get a slightly smaller plate, still covers the holes you mention.

Kevin

Was thinking about trying for a small personal number and going for a smaller plate, probably better than the large full sized plates though.

Bizarre bit of engineering, though. Mazda must have spent a fair bit of cash re-designing the bumper and air ducts, to get the extra air in and aid air flow, and then place them right behind the number plate! I can only assume, that they were designed with a tiny plate from Japan specifically in mind, with no thought to any other market!

Thinking about ways of adjusting the air scoops, to get around the number plate barrier......

The problem, as described in the original thread.

Basically here is the air intake on the 99 spec bumpers.

Here is the UK plate covering the intake very well!

One solution:

The air box takes its air from the air cavity behind the bumper. The base of this is just plastic, so cut a hole into this, and attach subtle duct...

Pic to show inside the bumper (taken from the engine looking forward, with the std air box removed)

View from the front, showing the new duct just to the side of the no. plate. Slightly shaped to funnel air up into the cavity and to the std air box.

Maybe a bit paranoid, but can only see that the no plate over the intake can\'t be good!!

Unless it\'s significantly restricted it shouldn\'t be a problem - the air system sucks air in and isn\'t dependant on an air-ram effect.

Obviously if the intake is actually blocked off partially then it\'s a problem!

The intake on mine sits behing the plate (although about 4 inches back from it).  A benefit of this is less liklihood of large amounts of water being ingested by the intake on very wet days...

Iain

QuoteOriginally posted by iaint
Unless it\'s significantly restricted it shouldn\'t be a problem - the air system sucks air in and isn\'t dependant on an air-ram effect.

Obviously if the intake is actually blocked off partially then it\'s a problem!

The intake on mine sits behing the plate (although about 4 inches back from it).  A benefit of this is less liklihood of large amounts of water being ingested by the intake on very wet days...

Iain

I can get a finger between the plate and the bumper - i.e. the gap is only about 3/4inch. I appreciate if yours is 4 inches away, then there will be no restriction to the air flow! Its a bit of fun, makes me feel better about it anyway and was dead easy and cheap to do!

Certainly can\'t hurt too much having the extra vent as long as it doesn\'t give a too-direct route through to the intake system for water (i.e. driving in heavy spray).

If you look at the standard airbox it\'s quite a convoluted route from the intake to the filter box and appears to be designed to not only split the air flow between intercooler and filter but to also prevent water entering the system.

I was looking at various possibilities for getting a cold air feed to aftermarket filters and was considering using the driving light hole on my bumper but that would basically suck up too much moisture at that height.  Havent\' got a decent solution yet that doesn\'t involve a dremmel and the front bumper!

Iain

QuoteOriginally posted by iaint
Certainly can\'t hurt too much having the extra vent as long as it doesn\'t give a too-direct route through to the intake system for water (i.e. driving in heavy spray).

If you look at the standard airbox it\'s quite a convoluted route from the intake to the filter box and appears to be designed to not only split the air flow between intercooler and filter but to also prevent water entering the system.

I was looking at various possibilities for getting a cold air feed to aftermarket filters and was considering using the driving light hole on my bumper but that would basically suck up too much moisture at that height.  Havent\' got a decent solution yet that doesn\'t involve a dremmel and the front bumper!

Iain

Very true. On the 92-99 bumpers, the std air scoop takes air up into the intercooler, and the air box draws the air from the same scoop. Its a very direct funnel, so heavy spray will be put directly onto the intercooler (good thing I guess), but the spray will also be directed up into the black air collecter and directly to the air box.
The 99 spec bumpers, have a split the air and intercooler scoops. The black air collecter that sits at the front just behind the bumber, now has 2 openings and pulls air from the cavity behind the bumper, not from the main intercooler scoop. So there is a reasonable air volume to pull from. The scoop I\'ve played with, will direct the air to the cavity in the bumber, it doesnt link directly to the air collecter.
Hopefully I won\'t be driving it too often in heavy rain anyway, so hopefully it\'ll never be a problem!

as i had to have my bumper off to sort the feed for the intercooler out as it was sat on top of the main bit of bumper, which gave stupid intake temps of >60 even driving off boost, i was able to easily rig up a nice cold air feed for the induction c/o one deceased vacumum cleaner ;)
Will post pix later if i remember......
Si

extension we had to do to standard scoop so it could scoop cold air from under the bumper:

& quickly bodged cold air feed for induction while bumper was off:

So is the ol\' vacuum cleaner pipe is still there, or was this a temporary fix? Sorted out something else or left as is?

well the previous week it was pointed in the intercooler scoop thing as that was sat in warm air land but didn\'t totally fix it so off came bumper to do above extension to scoop & while it was off i noticed i could stick it thru the front panel kinda thing to give the induction a bit of the cold stuff which seemed cunning so did....:D
Si

This kinda leads me to ask an intake related question:-

 Light cover venting/ducting, does it actually do anything worth while?
:confused:

Not being an expert, but rather thinking logically, then I presume it would depend on (i) the volume of intake air the engine requires,  (ii) the volume of air the extra intake supplies and (iii) the volume of air the cold air is being delivered into (i.e. dilution factor).

Difficult question to answer off hand, without doing alot of measuring! But bottom line would have to be anything is better than nothing, so if like alot of people, you\'ve got big foam filters sat un-heat shielded and potentially drawing hot under-bonnet air, then yes, it may make some difference! I guess the ideal would have to be some kind of heat shielded box, and then good ducting so that the majority of the intake air is cool, i.e. the hot:cold air ratio favours the cold rather than the hot!

I\'d just spent some time looking at the various types available, the only one which seemed to be designed as a scoop was at mariah motorsport.  Dont think I\'m gonna buy a single headlight cover and pay twice as much to ship it though!

Its puzzled me for a while, that people whip out the std air box, which sucks in cold air, and put on big foam filters. If you take the air box out, and look into the gap, what do you see? The backside of the rad for starters! Now I don\'t know how hot the air is that comes out of the rad, but since people say the rotary runs so hot and cooling is a big issue, then I presume it must carry some heat! The filters now sit right in the hot air flow from the rad. Not sure of the relative positive gains here.....std air box + filter which people say can be restrictive (some say not, though) BUT cold air drawn in....vs.....less restrictive filters but using warm/hot air from the rad/engine. Pros + cons with both routes, not sure which is best though.

i agree with the air box post. why would a mazda or any other company spend thousands of pounds developing an air box if all u need is a foam filter of a certain size. the box shields the intake from hot engine air period. i tried to open mine up to encouage cold air. drilled 20mm holes in the bottom and 20mm holes in the left side to get from wheel arch gaps. verdict. car went much much better but suffered with boost creep. end of experiment got scared.

sdminus,

 did you really drill holes in the air box? In the bottom of the air box!?!  That means you wouls have been suckiing in air without the aid of an air filter!!!

 I\'ve seen a fair few people posting about this, all I can say to you is DONT DO IT!!!  If your going to drill holes in the box (past the filter) then you may as well bin the filter and budget for a rebuild sooner than you\'d wish.....    :rolleyes:

In the std air box, the air is drawn in from the bottom of the box, the filter sits half way up, and the filtered air is taken from the space ABOVE the filter. Drilling venting holes into the base of the box is OK.

Nice little mod can be found here, with the std airbox:

http://www.rx7.org/Robinette/coldair.htm

True, but I\'m sitting here looking at an FC one.  Doh!

 I\'ll just get me coat...         :rollin

no all the air was filtered. only holes in the base of the box were made. i used the robbinette thing as a guide. once the filter was layed in the box ready for the lid none of the holes could been seen any more. this seems a common thing tohappen. seen may posts form the usa with same things happening. i think it has something to do with the waste gate and lack of fuel. not 100% tho. any ideas

the hose idea is basically the same as the k &n 57i filter kits. i am currently thinking about making a cool air intake. i have got the filters. gonna shield them from the heat. got a couple of ideas but also thinking of making a hole under the indicator. as far as i can work out i need to ram cold air straight to the filters as direct and unobstructed as possible. i am thinkin of trying to create same kind of cyclone effect by skewing the air as it enters the front of the car therefore increasing the velocity and amount. does this seem feasable. or will the turbulant air play havoc with the air sensing devices. is it true that efi cars dont like turblant air. the opposite to carb cars
scott