MQB Air Intakes (sorry....)

chrisrs180

Registered User
A subject with tired legs no doubt but I'll keep it as quick as possible.

My S3 8V has the usual turbo elbow/turbo muffler delete/airbox mods (cut out etc etc).

I've been messing with the airbox for ages and although not the smoothest flow of air before the panel filter, it does flow well. I've also smoothed/ported the inlets a bit (as they line up fairly poorly) and silicone sealed all the little gaps and holes between the plastic parts of the box/intake. Quite a few gaps appear especially under load.

Went to replace the stock OEM pipe (between airbox and elbow) with a silicone offering. Larger bore (but not massive size difference).

Definitely flowing more top end but the snap response of the throttle has certainly taken a hit. Not a huge amount and with spirited driving up the rev range I doubt you'd notice. However, as I am a stickler for low/mid range performance, I'd say I probably prefer it with the OEM hose in place.

As I see the OEM hose used on setups with hybrids and 500hp+, that's just fine with me.

Just wondered if anyone else has experienced something similar and if there are any aftermarket airboxes/mods which increase top end flow without slightly sacrificing the throttle response.

I'm wondering if an APR style box (incorporating factory front intake) with OEM pipe would increase the sharpness of the throttle even more, as it logically would appear to flow more smoothly whilst increasing filter size.

Basically swapping the chunky square design of the factory box to a smoother flowing design.

The open air/large filter kits don't really do much for me as they would exacerbate the lack of response even if they do make some extra hp up top.

It's all about drivability for me, numbers are great but if it takes longer to make them, not a huge amount of point on normal roads.

Any advice much appreciated.
 

Damo S

Registered User
modified airbox / filter and the turbo technics turbo inlet pipe. makes absolutely no difference to throttle response or midrange to me, but flows better at the very top end, and gives a little more induction noise.
 

chrisrs180

Registered User
modified airbox / filter and the turbo technics turbo inlet pipe. makes absolutely no difference to throttle response or midrange to me, but flows better at the very top end, and gives a little more induction noise.

Exactly the answer and solution I was looking for. Nice one.

I've seen a lot of people sticking bigger hoses on in the assumption that it will perform better, and it will, at the very top end.

Looks like the Turbo Technics has been designed with the best of both worlds in mind.

Cheers
 

AlS3BE

Registered User
Think the problems you are seeing is more a tiny wee 4 pot with a big turbo and most likely a bit of turbo lag. There’s no real fixing low/mid end power cause at the end of the day it’s still a 2.0l.
This is a case of no replacement for displacement. Size does matter. don’t get me wrong new tech like variable cam timing and variable vane turbo has made leaps and bounds to help this but some things can’t be fixed without a bigger engine.
just my opinion though
 

chrisrs180

Registered User
Think the problems you are seeing is more a tiny wee 4 pot with a big turbo and most likely a bit of turbo lag. There’s no real fixing low/mid end power cause at the end of the day it’s still a 2.0l.
This is a case of no replacement for displacement. Size does matter. don’t get me wrong new tech like variable cam timing and variable vane turbo has made leaps and bounds to help this but some things can’t be fixed without a bigger engine.
just my opinion though

I certainly agree with your no replacement for displacement mantra but the turbo's on these aren't what I would call big. With supporting mods (muffler delete,airbox tweaks, diverter valve upgrade, DTUK pedal box) you can all but eliminate most of the lag with the stock intake pipe as stated. With just an increase in bore of pipe it has definitely introduced 'some' lag (or effective 'delay') from somewhere.

My thoughs are that the 'ram effect' flow of air to the compressor inlet has slowed when at say 10-20mph due to the bigger hose, and whilst the larger hose flows more at higher RPM (where the 'ram effect' is nullified), at lower revs and speeds the difference can be felt. To a more or lesser degree anyway.
 

AlS3BE

Registered User
I certainly agree with your no replacement for displacement mantra but the turbo's on these aren't what I would call big. With supporting mods (muffler delete,airbox tweaks, diverter valve upgrade, DTUK pedal box) you can all but eliminate most of the lag with the stock intake pipe as stated. With just an increase in bore of pipe it has definitely introduced 'some' lag (or effective 'delay') from somewhere.

My thoughs are that the 'ram effect' flow of air to the compressor inlet has slowed when at say 10-20mph due to the bigger hose, and whilst the larger hose flows more at higher RPM (where the 'ram effect' is nullified), at lower revs and speeds the difference can be felt. To a more or lesser degree anyway.

with a bigger intake you are creating a bigger void to fill with air before the turbo creates a positive pressure on the intake until then it’s no different to any other 2.0 probably worse as turbo engines has low compression unlike NA. It’s the same with intercoolers there’s more space to fill with air before boost. Ideally turbo goes straight into intake manifold but that creates other issues like heat soak which results in loss of power.
Lots of stuff going on and most aftermarket parts are seeking peak power gains only so will sacrifice lower end.
Turbo mufflers delete is another I would think twice on as on some cars, not sure about s3, it creates a vortex/swirly type effect which will allow the fuel to burn evenly in the cylinders and better for low end power. Deleting it give you more air flow for peak power but again could sacrifice power elsewhere in the Rev range.
Tuning isn’t that straight forward.
I’ve seen rally cars on dynos before and they produce peak torque very early on and tails off very quickly as they need power low-mid end. This is great for racing but on road cars is not fuel efficient and not good for road driving. They also don’t need top speeds of 150 + as they will never each those speeds. These are similar small turbo cars putting out around 300bhp.
 

chrisrs180

Registered User
Interesting what you say on the muffler delete there. In my mind the 'vortex' created by the muffler would be a hindrance in most ways, hence its replacement for a straight pipe. I hadn't considered the effects other than sound muffling that it may have.

I think what you're saying about the 'void' etc is correct and pretty much what I was getting at (or trying to) with the larger bore hose creating extra delay, culminating in a slower throttle response.

As you elude to, there is a lot more going on here than just bigger pipe=more flow/power, albeit certainly a factor, in the grand scheme of things.

As always with these things a balance needs to be struck between out and out performance and drivability, the latter is not an issue when the engine is permanently above 3.5k revs (rally car etc) as the flow will be constant and strong. As with variable vane turbo's (and other hybrids) aircraft engines employ similar designs to provide low speed efficiency AND performance as well as top speed/power.

Certainly reaching the point of diminishing returns though when applying the same design theories to small engine mid-range sports cars . . . .

Got me researching hybrid turbos now haven't you . . . .
 

Damo S

Registered User
Exactly the answer and solution I was looking for. Nice one.

I've seen a lot of people sticking bigger hoses on in the assumption that it will perform better, and it will, at the very top end.

Looks like the Turbo Technics has been designed with the best of both worlds in mind.

Cheers

On a stock car it makes little difference, and only really comes into play when running higher boost. My car made 306bhp (I think) on stock map with an upgraded intercooler and intake (including the TT turbo inlet pipe). Not much of a gain with those alone given the cost.
 

chrisrs180

Registered User
Ah, should probably clarify, car is mapped and making 384 at clutch. Made 314 from stock with a few supporting mods (which I was a little disappointed with to be honest, considering it should be around 310 to start with) but now is nearer where I want it for sure.

Cheeers
 

Damo S

Registered User
Ah, should probably clarify, car is mapped and making 384 at clutch. Made 314 from stock with a few supporting mods (which I was a little disappointed with to be honest, considering it should be around 310 to start with) but now is nearer where I want it for sure.

Cheeers

In that case its well worth doing the inlet pipe. I would be absolutely amazed if there was any noticeable difference at all in the lower rpm range / throttle response.
 
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