Engine sounds different after CAI?

[Jontan]

I DIY my G9 CAI by pushing the stock air intake to behind the fog lights cover with the tube opening pointing towards centre of the car.

 

Now when I drive, I find that the sounds from the engine compartment are different from before I did the CAI.

 

Does CAI change the way an engine sounds?

Or did I do something wrong?

 

Please help

[Turbobrick]

CAI will cause an induction sound if U remove the stock airbox and add a cone filter. That is also known as "induction roar" and liked by some

[Madarmour]

I think it's the resonator box that plays a bigger part in muffling the sound, not the filter box.

[Cardinal]

Actually, from your post, I gather that you changed the configuration of your stock airbox, retaining the stock filter rather than putting in a cone filter and having the CAI tube right?

 

In that case, you shouldn't get any induction roar. But do bear in mind that the engine is somewhat like a giant musical instrument. The sound comes from the combustion chamber and the texture of the sound comes from the shape of the intake and the exhaust. I won't be surprised that any changes to the configuration will alter the sound of the engine. Even for K&N drop in filters, some people can hear the difference in sound already.

[Cool]

Yup.. CAI gives you more air and the sound will be different..

[Jontan]

You are right.

 

All I did was to detach the stock intake tube and drop it thru a hole so that it is now resting behind the foglights cover.

 

Nothing was added at all.

 

But I noticed that I am pulling higher RPMs before going into 2nd/3rd gear.

eg before I did my 'CAI' gears change at around 2000+ rpm

after 'CAI' gears change at abt 3000rpm

 

good or bad?

 

Cool: can take a look this evening?

[Cardinal]

I'm afraid I can't answer your question. I think the auto gearbox changes gear earlier or later depending on how hard you step on the gas. But I'll leave it to those who drive autos to volunteer a better answer

 

but regarding the longer tube, you see, the sound is coming from the engine and travelling back out of the intake pipes as well as exhaust. Just like if you take long pipe and speak into it, and then cut it shorter and do the same, the sound will be different. So your longer intake pipe will definitely sound different - probably lower in tone.

 

Even for my CAI which is a cone type, when I shortened it to a short ram, the sound was totally different. Even different brands of short ram intakes, with their different pipe shapes, produce different sound too.

[Alant]

Hi, I have taken out the top portion of the 'box with a short pipe' of my Civic EG8 between the radiator and the air filter box. And what I can see now is a pipe coming up from below the headlight connected to the intake of the air filter box. If not wrong, I think this is the resonator box?

 

Is it alright to remove away this box? Any side effect or positive effect ?

[Cardinal]

yah, that should be the resonator. It's purpose is noise reduction. So depends on how loud you want to car to sound...

 

But IMO, and only IMO, a resonator-less stock airbox sounds harsh and unrefined. If you want a nice sound from the engine, I'd definitely go with a cone type filter.

 

Positive effect, I think is less intake restriction, not 100% sure on that one. but your bottleneck should still be the airbox rather than the resonator, so don't think there's much improvement.

[Alant]

Thanks for the reply. I can feel and see (partly blocked) the pipe is slighly flatter near the inlet which is connected to the air filter piping right at the bottom. Think this the 'bottleneck' you mentioned.

This 'box' which I have remove is to actually allowing air to flow in or is to allow air to escape when flowing into the air filter from below the headlight ?

 

Can I connect a DIY pipe from the portion where I have removed to the front of bumper for air to escape or more air to flow in?

 

Thanks.

[Cardinal]

Actually I don't have a mental picture of what an EG engine bay looks like, but if you happen to frequent SHC, they have done a lot of permutations on how to sort out the EG intake issues. I would definitely check with them so that you don't re-invent the wheel..

 

Auto Dynamac in Ubi has a few solutions for the EG too, you may just want to swing by and seek their advice, look for Raymond.

 

As for the box you mentioned, if it's a resonator, it's purpose is like a muffler to reduce the noise from the intake, just like the muffler reduces noise from the exhaust.

 

A DIY pipe is only useful if it channels cooler air from outside into the air intake, but bear in mind that the longer your pipe, the more restriction you have, so you have to be very sure that the air is indeed cooler.

 

Hmmm... other than that, I really have to see your engine bay cos I can't really picture the pipes from your description.

 

One last thing, I would definitely recommend a cone filter, for the EG, there are plenty of cheap ones available, don't have to get branded ones like AEM. Just make sure the cone itself is a good one.

[Alant]

Thanks Cardinal.

[Yongwd]

I pulled out the whole air filter box and air duct leave throttle empty without any filter alone 1 week before I scrap my corolla

 

the induction roar is exciting

 

who cares the engine will blow? anyway I only manage to blow one toyota engine

[Andrewkb]

Actually length of intake pipe also matters !

 

That's why most new cars, e.g. VW, Honda all have variable length intake.

 

During low rpm, the "valve" in the intake pipe make the air goes the long way, but during high rpm, the "valve" closes and the air takes the shorter way.

[Yongwd]

this system is long invented by mazda on their 929

[Wrxblue]

I DIY my G9 CAI by pushing the stock air intake to behind the fog lights cover with the tube opening pointing towards centre of the car.

 

Now when I drive, I find that the sounds from the engine compartment are different from before I did the CAI.

 

Does CAI change the way an engine sounds?

Or did I do something wrong?

 

Please help

 

 

the suction 'noise' comes from the flow of air into the intake manifold of the engine.normally it is muffled by the resonator box where the air filter is stored.

 

the flow of this air is created by the 'vacuum' suction of the engine in the intake stroke of the engine and this induce the suction noise....

 

changing of the following would change the 'noise'

 

- Camshaft

- Manifold

- air filter

- air flow channel - if change to CAI

[Sparetyre]

So Shaggy, when is your Rex arriving??

[Andrewkb]

Opps .. paiseh ... I thut recent technology :-P