Drilling airbox to mimic f sport

CiaranMcK · May 13, 2022

Right. I feel like a muppet even asking this, but is there any argument for drilling a hole in the air box being a good idea?

My immediate thought is no. It’s just welcoming hot air into the engine. Stupid idea.

BUT. If the F sport comes like that at stock, without a separate feed surely there’s an argument that it shouldn’t negatively impact.

Is it worth the gamble for a bit of noise? Can I learn from someone else’s mistakes/achievements?

Thanks in advance!

PCM · May 13, 2022

Could it affect your insurance as a modification?

Don't think I would...

CiaranMcK · May 13, 2022

52 minutes ago, PCM said:

Could it affect your insurance as a modification?

Don't think I would...

Highly unlikely, to be honest. Unless there’s a reason to do so they don’t tend to pick over with a fine tooth comb. I know people who have crashed with undeclared induction kits and it’s not been mentioned. Illegal LED headlight bulbs, even ECU remaps (which I do not condone)!

If it can give a nice whoosh without impacting performance I’d do it. If they can come stock with a hole on the F then surely it can’t hurt?

H3XME · May 13, 2022

1 hour ago, CiaranMcK said:

Right. I feel like a muppet even asking this, but is there any argument for drilling a hole in the air box being a good idea?

My immediate thought is no. It’s just welcoming hot air into the engine. Stupid idea.

BUT. If the F sport comes like that at stock, without a separate feed surely there’s an argument that it shouldn’t negatively impact.

Is it worth the gamble for a bit of noise? Can I learn from someone else’s mistakes/achievements?

Thanks in advance!

If you're cutting a hole in the air box, I don't think it'll make much of a difference in terms of sound.. performance wise it won't make any difference at all as you're cutting the end before air filter.

Las Palmas · May 13, 2022

If you put cold air from air-condition in it, it could give you a bit more power as cold air has less volume than hot air

Would increase fuel consumption too.

samplify · May 13, 2022

I did this, but also removed the plastic baffles inside the airbox too. It does add sound and doesn't seem to come with any engine heat soak complications. If you're at all concerned, ask a breaker's if they have an airbox and do it to that one instead to compare. I got one for £30 and it came with a perfectly good MAF in it so was chuffed.

I used a hole saw for spot lamps and it worked great. Just make sure you have some sandpaper to get rid of all the marred plastic from the hole and all the jagged bits of baffle left over (pretty much impossible to get that all flush unless you have a proper handheld sander, probably more effort than its worth). Also, give it a rinse with a hose to get rid of any plastic dust. Yes, it is before the air filter, but no point clogging it up unnecessarily!

agent_dess · May 13, 2022

I did that when i had the IS250.... adds a nice growl 😁

CiaranMcK · May 13, 2022

I've just realised my airbox is snapped at both brackets so I need a new one anyway. Might as well drill it out before fitting!

agent_dess · May 13, 2022

Here is a comparison of the f-sport vs stock box:

You will need to cut the square out where the fins are.

J Henderson · May 13, 2022

I've had the F-Sport intake on my car for the past 5 years with absolutely no ill effects.

Just to clear something up. An F-Sport model has a normal intake & airbox just like any other IS250.

The one pictured above with the logo and cutout, was an accessory that was sold separately (only in USA, I believe).

CiaranMcK · May 13, 2022

3 hours ago, J Henderson said:

I've had the F-Sport intake on my car for the past 5 years with absolutely no ill effects.

Just to clear something up. An F-Sport model has a normal intake & airbox just like any other IS250.

The one pictured above with the logo and cutout, was an accessory that was sold separately (only in USA, I believe).

That makes me feel better about doing it!

did you get a US one or just cut it out? Did you also smooth it? I can’t help but feel they wouldn’t waste plastic (money) in the fins if it didn’t help airflow!

Linas.P · May 13, 2022

I think it may help separate water/dust, rather than help airflow. That said It is not clear for me how F-Sport one prevents water from entering airbox? Are there any other parts which should be present?

J Henderson · May 13, 2022

1 hour ago, CiaranMcK said:

That makes me feel better about doing it!

did you get a US one or just cut it out? Did you also smooth it? I can’t help but feel they wouldn’t waste plastic (money) in the fins if it didn’t help airflow!

I imported the official one.

11 minutes ago, Linas.P said:

I think it may help separate water/dust, rather than help airflow. That said It is not clear for me how F-Sport one prevents water from entering airbox? Are there any other parts which should be present?

The only difference is the lack of ribs/fins. I guess where the hole is, it doesn't see much in the way of water spray.

CiaranMcK · May 13, 2022

2 hours ago, J Henderson said:

I imported the official one.

The only difference is the lack of ribs/fins. I guess where the hole is, it doesn't see much in the way of water spray.

How much and where from? I’d prefer OEM!

J Henderson · May 13, 2022

Was about £250 all-in from eBay store toyotafactoryoemparts

I think you'll struggle to get one for that price nowadays though. 🤔

J Henderson · May 14, 2022

22 hours ago, Linas.P said:

I think it may help separate water/dust, rather than help airflow. That said It is not clear for me how F-Sport one prevents water from entering airbox? Are there any other parts which should be present?

Sorry to quote you again, but my interest was piqued enough about this to have a look in my airbox this afternoon!

Not too bad. Mostly fine sand-like dust with a few larger pieces of debris.

Similar story with the air filter. Interestingly, the upper half of the airbox was completely spotless and looked brand-new, so the filter clearly does it's job very well.

It's worth noting that this could be as much as 4 year's worth of build-up as I personally hadn't opened the airbox since 2018.

agent_dess · May 14, 2022

Water doesn't get in, I did the mod about 5 years ago, if I had another is250 I would do the mod again.

Linas.P · May 14, 2022

1 hour ago, J Henderson said:

Sorry to quote you again, but my interest was piqued enough about this to have a look in my airbox this afternoon!

Not too bad. Mostly fine sand-like dust with a few larger pieces of debris.

Similar story with the air filter. Interestingly, the upper half of the airbox was completely spotless and looked brand-new, so the filter clearly does it's job very well.

It's worth noting that this could be as much as 4 year's worth of build-up as I personally hadn't opened the airbox since 2018.

It would be interesting to check after driving in heavy rain. I guess you are ok - as you have reinforced air-filter, but perhaps not good idea to use standard paper one.

As well comparing to what mine looks like after 100k miles (and I am sure nobody bothered to clean it) - I would day your one looks significantly dirtier e.g. I have none of that fine sand, especially not around filter seal. Is that a problem? I don't know, maybe not, but it looks a lot dirtier.

Actually - even in this picture from Dess you can see how much dirt is in the airbox:

That is very similar how mine looks (I will take picture tomorrow). Just little bit of fine dust stuck around fins.

J Henderson · May 14, 2022

1 hour ago, Linas.P said:

It would be interesting to check after driving in heavy rain. I guess you are ok - as you have reinforced air-filter, but perhaps not good idea to use standard paper one.

As well comparing to what mine looks like after 100k miles (and I am sure nobody bothered to clean it) - I would day your one looks significantly dirtier e.g. I have none of that fine sand, especially not around filter seal. Is that a problem? I don't know, maybe not, but it looks a lot dirtier.

Actually - even in this picture from Dess you can see how much dirt is in the airbox:

That is very similar how mine looks (I will take picture tomorrow). Just little bit of fine dust stuck around fins.

The F-Sport filter has a kind-of rubberised frame which seems to seal really tightly so I don't think any dust makes it through. Like I said, the top half of the airbox was spotless.

Anyway, I'm now rocking an OEM paper filter as I washed the reusable one after taking the pictures (cleaned out the airbox too). I will give the F-Sport one a week to fully dry out before refitting it.