Induction kit vs air filter

Induction kit vs air filter

Author
Discussion

dabiscuit

Original Poster:

53 posts

172 months

Thursday 29th March 2012
quotequote all
What is best folks? I have a 2.5L WRX STI, its running about 320 at the moment, but want to edge it up to the 350 mark. I have a feeling an induction kit is going to be a better option.

paulmoonraker

2,850 posts

170 months

Thursday 29th March 2012
quotequote all
The standard air box is more than adequate for 350. Unless mapped properly an induction kit can cause problems (somebody will shortly be along to elaborate on this).

JimmyspecC

17 posts

173 months

Thursday 29th March 2012
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what he said^

you would need to remap it again if you have the induction kit plus you dont need it for that power.

Vixpy1

42,674 posts

271 months

Thursday 29th March 2012
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Just a good Panel filter, Decat or Sports cat and your away.

JollyGrnMonster

887 posts

204 months

Thursday 29th March 2012
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Agree for 350 the standard box with panel filter like the cosworth for example works well.
Perrin induction kit works quite well if you want more. Mapped one to 376bhp/400lb with one on this week

RB Will

9,934 posts

247 months

Friday 30th March 2012
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It will make more fun noises with an induction kit on

paulmoonraker

2,850 posts

170 months

Friday 30th March 2012
quotequote all
RB Will said:
It will make more fun noises with an induction kit on
Just take the snorkus and ram scoop off. Then you get the induction roar and dump valve sound wink

AMGreg

179 posts

162 months

Friday 30th March 2012
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JollyGrnMonster said:
Agree for 350 the standard box with panel filter like the cosworth for example works well.
Perrin induction kit works quite well if you want more. Mapped one to 376bhp/400lb with one on this week
Jolly Green Monster mapped mine with the Forge kit. Fantastic job done! Still has a CAT but 352bhp / 390lbft and very pleased with the results - feels very different to drive :-)

dabiscuit

Original Poster:

53 posts

172 months

Saturday 31st March 2012
quotequote all
hi again folks just thought id report my findings. my mate and i successfully fitted the induction kit. its an hks racing suction reloaded and all i can say is WOW. the car was quick before but now its just so much quicker especially the in gear pull. also makes a wicked noise. not sure of the figures but i can feel a good improvement!

paulmoonraker

2,850 posts

170 months

Saturday 31st March 2012
quotequote all
dabiscuit said:
hi again folks just thought id report my findings. my mate and i successfully fitted the induction kit. its an hks racing suction reloaded and all i can say is WOW. the car was quick before but now its just so much quicker especially the in gear pull. also makes a wicked noise. not sure of the figures but i can feel a good improvement!
Really? You can actually feel the difference, despite the extra heat soak from the engine? And without a remap?

Vixpy1

42,674 posts

271 months

Saturday 31st March 2012
quotequote all
High chance of it going Bang with an induction kit and no remap on the 2.5

AMGreg

179 posts

162 months

Saturday 31st March 2012
quotequote all
dabiscuit said:
hi again folks just thought id report my findings. my mate and i successfully fitted the induction kit. its an hks racing suction reloaded and all i can say is WOW. the car was quick before but now its just so much quicker especially the in gear pull. also makes a wicked noise. not sure of the figures but i can feel a good improvement!
Hi, if you have not had it re-mapped as mentioned, make sure you get it done as soon as possible. The engine will be sucking in more air due to the reduced resistance between the induction kit and the standard filter. The MAF will not be accurately sensing the airflow into the engine and it is highly likely it will not run properly. There is the potential of causing damage. Drive staying off boost and get it re-mapped asap.
If you have had it mapped with the kit on - happy days, and enjoy it!

dabiscuit

Original Poster:

53 posts

172 months

Saturday 31st March 2012
quotequote all
AMGreg said:
Hi, if you have not had it re-mapped as mentioned, make sure you get it done as soon as possible. The engine will be sucking in more air due to the reduced resistance between the induction kit and the standard filter. The MAF will not be accurately sensing the airflow into the engine and it is highly likely it will not run properly. There is the potential of causing damage. Drive staying off boost and get it re-mapped asap.
If you have had it mapped with the kit on - happy days, and enjoy it!
Cheers for the tip, already getting on the remap!

paulmoonraker

2,850 posts

170 months

Saturday 31st March 2012
quotequote all
Induction kits are a grey area on Scoobies. I don't know why people fit them to be honest, unless your going for big power gains, but that means replacing the turbo... Just take the snorkus out if you want the sound...

dabiscuit

Original Poster:

53 posts

172 months

Sunday 1st April 2012
quotequote all
whats the snorkas? im starting to wonder if its worth it at all now! probably should have done my research properly. at least the air box should relatively easy to refit. should i just get remap for my set up? i dont want to lose the potential of power but id rather my engine not go pop!

paulmoonraker

2,850 posts

170 months

Sunday 1st April 2012
quotequote all
First take the ram air feed off. This runs right over the rad at the front so causes heat. The snorkus is inside the drivers side fender in front of the wheel. James at GRD just unbolted the one bolt that holds it in place (near air box) and then pulled it out from under the car. Search on YouTube, as the is a popular DIY mod...

You'll now have cooler air sourced away from the engine, the induction sound, and you'll also hear the standard recirc valve working...

You can also take the stupid nappy off from under the engine as this will make your engine run a bit cooler.

Edited by paulmoonraker on Sunday 1st April 09:44

ScoobieWRX

4,863 posts

233 months

Sunday 1st April 2012
quotequote all
paulmoonraker said:
You can also take the stupid nappy off from under the engine as this will make your engine run a bit cooler.
I'm not sure if that's quite right.

I've always believed the undertray is there to promote airflow ingress and exit around the engine/engine bay.

Air comes in at the front of the car and creates high air pressure areas in the engine bay where airflow stalls, stops circulating and stops or slow down any further air entering the engine bay if it doesn't have a route out.

Air will always excape down the path of least resistance like water so the tray under the engine having a large gap at the back promotes air to escape via that route by creating low pressure areas down the back of the engine/engine bay and over the tray to maintain a constant flow in and out.

Removing the undertray allows air to enter the engine bay from underneath, this creates high air pressure areas and turbulents low down and stops airflow coming in and going out properly or at all. That then raises underbonnet engine temps, makes your FMIC or TMIC less efficient, specially a TMIC, and all the negatives that go with that.

It's not just Subarus, just about every modern car out there has an engine undertray, i'm sure mostly for this reason. I've no idea how the tray affects exterior aero, it probably does, but i'm pretty sure what i've written although not scientific is the general gist of it.

If i'm wrong i'm more than happy to be corrected and educated. smile

paulmoonraker

2,850 posts

170 months

Sunday 1st April 2012
quotequote all
A certain person who I think is fairly cluded up took it off when doing some other work on my car, and without question the temperature gauge was slightly less than when it was in place (only slightly, but enough to notice).

Regardless, your academic reasoning is very good. Whether its right or not, well, I have no idea.

ScoobieWRX

4,863 posts

233 months

Sunday 1st April 2012
quotequote all
One of the most common reasons in my experience for removing it, as i did and some people do, is because my aftermarket headers melted the fireproof material attached to the inside of the tray, and then went on to almost completely melt the plastic of the undertray all the way through. I didn't want the tray catching fire so i removed it. I didn't remove it because it would help cooling.

Aftermarket headers melting through the undertray material is not uncommon and i've seen lots of undertrays having suffered this issue.

I was though concerned about the effects on underboonet temps after i'd removed the tray only because of what i believe is correct although i have to say i didn't notice engine temps particularly going up via laptop and diagnostic software monitoring ECT's, and i didn't see them going down either. I had no way at the time though to accurately measure before and after underbonnet temps. Nowadays i have a hand held IR Thermometer and if i'm concerned about underboonet temps, specially in the summer, i use that to take a reading though the intercooler scoop.

dabiscuit

Original Poster:

53 posts

172 months

Sunday 1st April 2012
quotequote all
Not to mention it would probably change the handling characteristics at the front end. I assume with more air going in, you're looking at more down force at the front, albeit not entirely where you'd want it to go!

Putting an induction kit does create a lot more space for air to flow mind.

That white box that comes connected under the air filter box, is that to collect unwanted moisture?