Air Intake Question....

[kicker1_solo]

I wasn't sure where to post this, so here it is. I have a mazda, and I was thinking about putting a hood scoop on it in the middle of the hood to have the air go straight into the carb. I was wondering if you guys could tell me some of the advantages and disadvantages of it. And does anyone have some pics, or a how to page on how I could go about doing this so I could get some ideas for it. And please don't flame me because of the mazda bit, I do have a honda too.

[highbrid]

ive always wondered what happens when it rains hard with a hood scoop like that. i mean the water would be sucked right into the engine, hence a blown motor. that is the only disadvantage i can think of. i was thinking of getting a hood with a hood scoop in it but then this thought dawned on me. maybe make like a little cover type thing to put over it when it rains or if you go through a car wash.

[RickDaTuner]

the advenatages would be great you have a cold air intake without the piping so it would be a direct flow no temp loss pluss when your out on the freeway or whatever it is that you guys call it. you would be getting a ram air typ effect and since its a carb you dont ahve to worry about fuel mixtures cuz the carb does it for you the only thing I think you would have to worry about is bugs n stuff but a filter would easily take care of that as foe problems when its raining I dont think that you would have to worry to much. if a rain drop would get sucked in the intake the filter would either soak it up or make it into a mist so that all you get in effect of that would be a little extra smoke comming out from your exhaust. unless you ran a frikin garden hose into your intake will driving youll be alright I think what highbird was concerned about was a heat shock fracture happening with water wich would happen only if the amount was as high as previously stated

you know a cool Idea would be a motorized switch box that would close the hood vent and open one that was inside the hood toi really prvent any water damage

[highbrid]

the ultimate cold air intake would be to drive around without a hood. is that legal to do that? They did that in the fast and the furious and you know if it was in that movie it just has to be true

[VTEC_boi]

LOL - my friend had to do that once...his carbon fiber hood messed up so he drove around for a short while w/o a hood hahahaha

don't worry - he has a new CF hood now

[fritz_269]

I really wouldn't be worried about a little rain, as long as you covered it up when it was turned off. You have to have a LOT of water in an engine to hydrolock it. A Florida monsoon might do it, but you wouldn't want to be driving in that anyway. The water wouldn't permanently hurt a running engine, but your power would be way down.

You didn't mention a filter - you do plan to have an air filter - right?
(you damn well better!)

It's also important that there be a sealed chamber of significant volume between the filter and the carb intake. The carb relies on having a large volume of air in a plenum right above it; without it, you'll have problems with off-idle stumbles.

[kicker1_solo]

Well I was going to have a screeen on it, like set back 2-3 inches from the very front of the intake part. Then I was going to have a filter back a ways. Any other ideas or concerns. And thanx for all your thoughts on this so far.

[kicker1_solo]

here's a couple pics, just a general idea of what I want to do....

[kicker1_solo]

another

[kicker1_solo]

one more

[jeffie7]

Keep in mind if you do that you might have to rejet your carbs if I was you I would do a cowl hood setup that way rain is less of a problem

Jeff

[MARKUSIUDIUS]

YOU WONT HAVE TO REJET YOUR CARBS BECAUSE THE AIR MAY EVEN CAUSE A BLOCK AT HIGH SPEEDS IN THE FRONT OF THE INTAKE. WHAT HAPPENS IS AS THE AIR FORCES IT WAY IN, THE ENGINE WILL ONLY NATURALLY SUCK SO MUCH BEFORE IT ACTUALLY STARTS PUSHING SOME BACK OUT, WHICH MAY CAUSE A REVERSE AFFECT AT THE MOTH OF THE SCOOP. BUT DONT WORRY THE ENGINE ALWAYS TAKES WHAT IT NEEDS AND A LITTLE BIT MORE. IF YOU DID REJET YOU MAY GET ALITTLE MORE POWER OUT OF HER FROM THE LITLLE EXTRA AIR. THE RAIN IS NOT A PROBLEM, WILL CALL IT WATER INJECTION AND NO YOU DONT HAVE TO KEEP A CHAMBER OF AIR BETWEEN THE FILTER AND THE CARB MOUTH, THAT WAS CRAP YOU NEVER DO THIS ON SINGLE FILTER SET UPS, TWINS, TRIPLES AND QUADS ETC, ETC. THE BEST WAY IS TO KEEP YOUR BOTTOM OF YOUR FILTER HOUSING MOUNTED TO THE CARB AND PUT DOWN SOME MESH AND THEN A UNIVERSAL K&N FILTER OR THERE ABOUTS WHICH IS CLAMPED ON. THEN MAKE UP SOME SORT OF COVER WHICH WILL SEAL BETWEEN THE BONET SCOOP AND THE FILTER HOUSING. ALL VERY SIMPLE
HAVE FUN.

[Someguy]

MARKUSIUDIUS- There's an interesting little button on your keyboard about half way down on the far left called the "Caps Lock". You have some good/interesting replies, but they are a real pain in the ass to read. Give the little letters a chance!

[kicker1_solo]

thanks a lot for the comments guys.

[fritz_269]

Originally posted by MARKUSIUDIUS
.... AND NO YOU DONT HAVE TO KEEP A CHAMBER OF AIR BETWEEN THE FILTER AND THE CARB MOUTH, THAT WAS CRAP YOU NEVER DO THIS ON SINGLE FILTER SET UPS, TWINS, TRIPLES AND QUADS ETC, ETC.

It's not crap. Don't be so rude, particularly when you're not correct.

It's actually a fairly well know fact. You need to have a minimum of about two times the venturi volume in a plenum over the carb. Here's why: At throttle tip-in the engine pulls a small vaccum against the filter. If the plenum volume of air it pulls is very small, this vacuum spikes sharply and the carb dumps fuel thinking that air velocity is high (which it isn't). This causes a tip-in rich condition and an engine stumble. If there is enough air in the plenum, it buffers this effect, the plenum vaccum will be small, and the carb will meter fuel correctly.

On top of that, a large intake plenum (before and/or after the carb) buffers the turbulence caused by intake valve reversion.