View Full Version : RS5: What intake to get?

08-23-2018, 08:50 AM
Now that I installed my Capristo, itís on to the next money drain! What intake do you guys recommend?

Eventuri seems popular but pricey. I saw ARMA has one out...

Curious to hear everyoneís thoughts. Thanks!

08-23-2018, 09:51 AM
Heya, ECS also makes one!

Eventuri seems to be 'THE' intake, however, I think it's way overpriced, and you're paying for the 'look'. It does seem to add decent power.

I'd actually never heard of the ARMA intake. The price is right, but can't seem to find any information on power gains? I'm going to shoot them an email!

P.S - How hard was that RSNAV to install? Is it a separate box that plugs into the Audi screen?

08-23-2018, 10:08 AM
P.S - How hard was that RSNAV to install? Is it a separate box that plugs into the Audi screen?

It took around an hour ó the biggest part is removing the gear shift surround/center console to route the USB cable to the armrest (replacing the cigarette adapter in there). You can route it somewhere else, but that's probably the cleanest install.

The instructions are pretty clear, you do need OBDeleven or VAGCOM to enable the green menu to enable the AUX port, as that is how all audio from the unit is routed.

I am waffling on Audi quality for music. I'm not always listening to music (that Capristo is music haha) but the sound is definitely different. Leaning towards preferring stock MMI/bluetooth audio quality, but again, not the biggest deal to me.

08-23-2018, 10:55 AM
Why do you want an intake?

Ape Factory just proved that it makes zero difference. In fact, OEM performed ever so slightly better: https://www.audizine.com/forum/showthread.php/823878-The-JHM-Stage-1-RS5-B8-Tune-Thread-Prerelease?p=13261020&viewfull=1#post13261020

08-23-2018, 11:35 AM
For me the Eventuri is for look and engine tone change. My butt dyno felt a difference when I installed it and Eventuri has power and torque curves under ideal conditions showing "slight" improvement.

08-23-2018, 12:15 PM
Why do you want an intake?

Ape Factory just proved that it makes zero difference. In fact, OEM performed ever so slightly better: https://www.audizine.com/forum/showthread.php/823878-The-JHM-Stage-1-RS5-B8-Tune-Thread-Prerelease?p=13261020&viewfull=1#post13261020

I only want for a positive tone change. Which is why i donít want to spend too much. I also canít see my engine bay while driving 😂 so I donít care how beautiful the eventuri is ó and it is gorgeous!

08-23-2018, 02:20 PM
I only want for a positive tone change. Which is why i donít want to spend too much. I also canít see my engine bay while driving 😂 so I donít care how beautiful the eventuri is ó and it is gorgeous!

i look at my engine every night.....[drool]

08-23-2018, 03:48 PM
i look at my engine every night.....[drool]

Just look? 😂

08-24-2018, 09:51 AM
Why do you want an intake?

Ape Factory just proved that it makes zero difference. In fact, OEM performed ever so slightly better: https://www.audizine.com/forum/showthread.php/823878-The-JHM-Stage-1-RS5-B8-Tune-Thread-Prerelease?p=13261020&viewfull=1#post13261020

Oh please!!

Thereís more dyno results out there with proven gains from Eventuri and funny enough they all show the same 20hp gain, proven on dynos in UK, Dubai and Australia, a crappy under reading US dyno thatís so far out of date it canít even display RPM or torque and youíre taking that as a result?

Ape Factory
08-24-2018, 02:12 PM
In all fairness, the dyno can show rpm and torque we just couldnít locate a good trigger signal wire. Testing again next Thursday so if you can hold off a week....

Ape Factory
08-24-2018, 06:58 PM
Just going to add one more comment and leave it alone until I get more data but I'm not planning on selling my intake any time soon. I'm the type of person that is more concerned with performance than looks and I'd sell it in a heartbeat and put the money towards something else the would actually make the car go, stop and turn more quickly if I truly felt it didn't provide any performance gain.

Ape Factory
08-25-2018, 03:59 PM
Today I took a long look at the Eventuri intake.

About 70% of an engine's intake restriction is in the cylinder heads. Yes, it'll vary by a few percentage points but that's a solid average number for a 4V head. That's in the cylinder head alone, doesn't include the intake manifold or the intake.

I wonder if Eventuri would give us the surface area for their redesigned filters. We need to compare that to the OEM or K&N filter. If it has less surface area overall, it won't flow as much air. No way around it unless we're talking forced induction

Our airbox will NEVER see positive pressure with the way it's designed. It is not, in any way shape or form, a "ram air" system. To look at a true ram air system, take a look at something like the Aprilia RSV4 or the Kawasaki ZX-10. Even then, the airbox doesn't see pressurization until triple digit speeds. Therefore the intake is always under vacuum, it's always sucking air in.

I took the "scoops" off after looking at how they sit against the top of the radiator. James had mentioned the slight redesign of the front scoop system. There's a piece of metal that gets bolted to the plastic OEM intake front lip and to the top of the carbon scoop. It mates the two together. Now the floor of the carbon scoop and metal connector, what the airflow hits and flows up towards the mouth of the OEM intake, sits below the front support for the grille. This is a thick black plastic piece. At any given angle, there's about an inch gap between the top of the plastic support and the carbon/metal scoop. It's a mail slot.

Here's a photo, front of the gar is on the left. You're looking at the passenger's side.
https://s20.postimg.cc/492hcjwel/Air_slot.jpg (https://postimg.cc/image/vjnskgzbd/)

Once the air makes it past the radiator, hits the scoop and shoots upward over the a/c condenser and radiator, it enters the OEM portion of the intake's mouth. There are two dividers which help to direct airflow. The Eventuri portion of the mouth forms a hard wall on the right inboard portion of the mouth and to me, it looks like a restriction. Best I can tell, there's no reason for it to be there.

Inside shot
https://s20.postimg.cc/w96kwws65/intake_mouth.jpg (https://postimg.cc/image/zg14gjcm1/)

Little better angle..
https://s20.postimg.cc/wko19jqkt/EAF705_C1-6457-42_FE-8208-_FBC0_E7_C31_AB8.jpg (https://postimg.cc/image/o2el57k21/)

Here's a shot of that same intrusion but from the outside with the scoop installed. There's no real reason for it AFIK. I'm not sure why they didn't just make it a smooth transition from the outside edge of the OEM scoop to the leading edge of the bell mouth. Maybe they saw something in their fluid dynamic computational models.
https://s20.postimg.cc/npn6z7ozh/581_E7_D94-62_EB-46_DA-9_E4_D-056_A5_FF19_B53.jpg (https://postimg.cc/image/g9nxdf1a1/)

Looking through the front grille, there's a big piece of the grille support which blocks the top edge of the intake scoop. The S3 guys apparently have a similar edge and end up cutting it out to make the air path more direct and larger. It'll never be a true ram air without a fully sealed intake mouth and box.
<a href='https://postimg.cc/image/xod7ic761/' target='_blank'><img src='https://s20.postimg.cc/xod7ic761/5_EC85_FB7-94_E6-4_B72-_B003-75083_CAE3544.jpg' border='0' alt='5_EC85_FB7-94_E6-4_B72-_B003-75083_CAE3544'/></a>

To top it all off, that grille support has three lips which look like they could be trimmed, not just one.

Another look at the air intake "slot". I think there's still room for improvement in the actual angle of the scoop. There's room to move the floor back towards the condenser and increase the angle of the carbon scoop from horizontal to even more vertical. Honestly, a sealed snorkel would probably work just as well, no scoop needed.
https://s20.postimg.cc/ych04fmsd/D8_C6_EECE-_F638-413_C-9425-1_DCFBAA5633_C.jpg (https://postimg.cc/image/z1zsgsnbt/)

https://s20.postimg.cc/orxdhmxh9/AA3_A11_AE-13_C4-42_F5-8432-_C032_F2_BDF15_A.jpg (https://postimg.cc/image/sbjb7g06x/)

I think this design was implemented to preserve the mouth of the OEM intake. I do think it can be designed better and the OEM portion eliminated.

Still holding off judgement until I get back on the dyno next Thursday.

https://s20.postimg.cc/497j9i2od/5_BC1_E9_D3-68_B8-40_C3-_AD09-_F60600_C76_BE2.jpg (https://postimg.cc/image/4yqblv37t/)

https://s20.postimg.cc/4lyxfpnj1/4_EB2875_D-89_AA-485_A-9_F5_A-_DE99_A287_FC81.jpg (https://postimg.cc/image/yqne12sm1/)

Shot from the top. For the life of me, I can't think of what the cheese grater holes are for other than to possibly prevent hydrolock. It'd have to be one hell of a puddle for that to even come into play though. Seems like one could seal that up. If you look at your hood, you'll see those holes superimposed by the dirt that gets sand blasted onto the paint.
https://s20.postimg.cc/6p4aqgbx9/79_BA6157-7_B5_E-4_B64-_A172-4384_A6_A82_AE0.jpg (https://postimg.cc/image/6ccwk9tnd/)

https://s20.postimg.cc/n04emsja5/2_CF0686_B-6756-453_E-9848-439_BC3380_BC0.jpg (https://postimg.cc/image/usv2erp95/)

I think this design was implemented to preserve the mouth of the OEM intake. I do think it can be designed better and the OEM portion eliminated.

Still holding off judgement until I get back on the dyno next Thursday.

08-25-2018, 08:29 PM
I share your thoughts on those lips, Iíve been tempted to remove the grille and go at them with a dremel or make a matching upper scoop to smooth out the airflow (those sharp edges will create turbulence).
The cheese grater holes are there as a safety net, remember Audi builds these to run in the snow and that front grille could soon block up on a bad day. I carbon skinned my holes over, it made no difference, at least not anything I could notice.

Take a look at the OE routing too Michel, it hits an even worse wall as it enters the convoluted tube, once in the airbox it has to change direction twice before it heads to the throttle, from that perspective Eventuri have made a big improvement in flow.

Not sure I share your concerns on filter size, look at the other dyno charts (not yours), you see the plots separating between OE and Eventuri at around 4000rpm, they continue to increase that separation all the way up to red line where itís a 20hp difference, I think thatís from the improved flow and quantity of air reaching the throttle.

Take a look in the parts catalogue at the pre facelift model RS5 intake, they have a nice 1 piece plastic scoop that drops down much further than the later model cars, not sure why Audi changed that design, maybe because of the new front grille causing a restriction in this area?

Ape Factory
08-25-2018, 10:57 PM
Snow huh? Well I guess that pretty much solves it for me, they're getting covered up! That would have to be one hell of a snow storm.

One thing I plan on doing is measuring vacuum. I'll do a few logs to redline and measure the pressure difference between the two intakes (OEM vs. Eventuri). That'll tell me right there if they have more surface area or if one is more restrictive overall than the other. I also have the V1 Eventuri filters. I could just cut them and lay them flat and measure I guess. I do suspect the Eventuri filters have more filter area. I'll do some measurements tomorrow if I have time. Theoretically speaking, if the Eventuri is less restrictive, it'll show by measuring vacuum in the intake manifold. If there's a more restrictive portion of the induction system downstream, the intake portion won't show any gains.

Thinking out loud...look at it like a straw. How restrictive the straw is depends on the straw's diameter, length and volume of the pump on the other end. A 3" diameter straw of a specific length will have less restriction on a 3-Liter pump than a 5-Liter pump.

Now add multiple "pumps" aka cylinders and other parameters start to become more important, mainly overall intake volume (length x area of the base). Then add restrictions on the size of the straw. Aerodynamics and airbox pressurization can, theoretically, minimize restriction for a given induction volume. It's like aiming arrows at the same hole. Every manufacturer has limitations on the size of the airbox. It's just a limitation of packaging.

But picture this if you will...Assume the straw isn't the most restrictive portion between it and the pump or cylinder. Assume there's a valve between the straw and the pump, aka the throttle body. Then you have intake runners and valves. Again, 70% of the restriction is in the cylinder heads themselves. That leaves 30% for the intake system (manifold and everything before the throttle bodies). We have two, so divide that in half, 15% per cylinder bank. Shrink that again as the intake manifold is probably costing another 20%. So 10% for the intake itself. Divided in two. 5%. Now how much of a reduction in restriction do you need to make with an intake to show a significant gain in wheel hp?

So if you enlarge the straw at the intake end but nowhere else, is the pump going to be able to suck in more air with less restriction, less pumping losses? Probably not. That's why it's so hard to have real gains with an intake on a naturally aspirated engine. Granted, air density can make a difference which is why "cold air" intakes do make hp. Are we getting any of those density benefits with the Eventuri over stock? Dunno yet.

I did a few logs today and my IAT's were about 25-30 degrees over ambient at WOT with the Eventuri. The IAT's drop at a pretty good rate at WOT once the revs get up there. I obviously need to measure the OEM airboxes. Food for thought at the very least.

With all of that said, I was looking at the overall design of some of the other offerings and I can't say I was that impressed. I think the Eventuri would still be the "winner" but I do think there's room for improvement. The winner is the one that'll have the most consistently low IAT's over a wide range of operating conditions. Density is going to win over relatively microscopic improvements in a 5% airflow window. That's why your car feels so much faster in 70 degree temperatures than it does in 100 degree temperatures despite no change in intake design.

08-26-2018, 02:29 AM
Also thinking out loud back to my aerodynamics classes. The straw theory is cool if the intake was a constant diameter, but they never are. The throttle housing diameter will be the ultimate limit to the whole intake, you can go as large as you like before this but the volume of air entering the engine is ultimately limited by the throttle diameter. So what can you do to make an improvement, well air has mass so a moving column of air has kinetic energy, if you can speed up the air flow as it approaches the throttle then you could increase the amount of air going down the intake. An intake will have a certain amount of Ďram airí due to the kinetic energy of the moving column of air and if you start to narrow the diameter of the air passage then you will increase its velocity (Venturi).
The OE intake changes volume, dimension and direction several times before reaching the throttle, the Eventuri has an advantage here so should in theory move more air or at least move the air more efficiently in what is a relatively direct path to the throttle.

The only area I would like to improve further on the Eventuri is the front grille and scoop area, I think this will be quite turbulent air so could be improved by smoothing the path of air, I may mock up an improved scoop making it more of a duct having an upper and lower rather than just the lower plate. I donít think it requires a larger airbox, the size seems appropriate to supply a 2.1ltr motor (one side).

Ive got a bunch of hose joiners and reducers heading my way to rebuild the intake, Iím getting rid of those nasty Audi overengineered vacuum connectors on the inlet ducts and replacing them with a 19mm -13mm reducer tube and normal hose clamps, also for some longer joiner hose to give more adjustability and a couple of hump hoses to allow some movement. Iíll look at the grille area when itís all out of the car and see what I can do. Maybe even order a replacement from Audi so I can cut it up to fabricate something better.

Ape Factory
08-26-2018, 06:42 AM
That was sort of my point, there are greater restrictions after the OEM or Eventuri intake (throttle body, intake manifold runners, flappers, and valves) which would negate any improvements before. And then there's the filter area.

Going back to the straw analogy (and I know it's not perfect), what if you replaced the straw with a cone? It would narrow down into the same 3" diameter where it met the throttle body and the overall length would be the same but it'd be 5" at the other end instead of 3". Would it be less of a restriction? Theoretically I'd say yes but it depends on whether or not the 3" diameter near the throttle body is the actual restriction right? And then there's the restriction of the throttle body itself.

One thing I didn't throw out there was the difference between airflow under pressure and airflow under vacuum. Are the aerodynamic principals the same when you throw an object into the airflow for both? How does shape of the object matter? I couldn't find a good answer. The air entering the engine will never see greater than atmospheric pressure except possibly at the valve. I know engine firing order and pulses, just like exhaust but in reverse, can create specific intake design needs but I always thought it was mostly from a volume and velocity standpoint. I could be wrong.

If you look at the Aprilia RSV4 Factory's intake, initially it had motorized intake runners that would vary in length (not sure if the 2017+ has it) plus the ram air effect. There are a few cars that also had variable inlet tracts to help fatten up the powerband and they do take air pulses into account as the valves close and the kinetic energy of the air mass slams into a closed valve. That's the only point I could see positive pressure being produced. But that's at the intake valve.

Taking the radiator cover off and looking at the top slot, the area in between the front grille and the condenser/radiator, I thought utilizing more of that along the width of the entire front end might be beneficial. There seems to be room for an increase in the width of the ducts overall and using a new radiator cover to help in that department.
https://s20.postimg.cc/eumcood1p/C3253_DA9-827_A-4457-_BB15-451608_F89_A21.jpg (https://postimg.cc/image/ug3o8mozt/)

Get rid of this and increase the width of the mouth?
https://s20.postimg.cc/q6yy6eoal/26_D34513-2_E77-4979-_BC2_E-_D90_BD8446_CE7.jpg (https://postimg.cc/image/71vown9mh/)

If I have time on the dyno, I'm going to try a few things like making a run with the radiator cover off and also maybe with the whole front section, the scoop, removed altogether. I realize at speed, there's pressure buildup and cooler air being forced through the heat exchangers and up into the intake mouth and there's probably a definite benefit to that at speed. So the test won't be real world applicable as we'd never drive around sucking hotter air in than we would otherwise with the scoops.

Air will always take the path of least resistance so trimming up those edges on the bumper support is going to help too as it'll probably reduce turbulence like you mentioned.

But the more cool air we can get in there, with the least amount of heat soak, the better.

08-26-2018, 08:32 AM
Although air is compressible it still follows fluid dynamics so in your cone example above, the air velocity has to increase if you reduce the diameter of the duct.
Evidence of the intake being in a state of positive pressure is deposited in the form of small circles of dust on the under surface of the hood where those holes we are assuming are for snow blockages are venting off the inlet air. I tried closing these off when I skinned mine in carbon but as I said, there was no noticeable difference, just one less area to wipe clean.

The cover area actually looks to be a form of Venturi as it certainly narrows in cross section before entering the airbox, with the Eventuri it enters the bell shaped airbox which is a second Venturi somin theory,the air should keep accelerating.

So the throttle diameter is the limiting factor but if you can cause a ram air effect by accelerating the air mass then you can move more air through that throttle than just atmospheric pressure.

So is pressure better than vacuum, well if the are equal then itís just back to that moving column of air again, they should both be the same..... shouldnít they?

Ape Factory
08-26-2018, 10:06 AM
Well there's no doubt that there's positive air pressure at the front of the car, those circles could be deposited when the throttle is shut vs. open though. I guess we could get a pressure sensor, install it in the OEM airbox after the filter and see. Wouldn't be too hard I guess.

I just don't know the answer to the pressure vs vacuum scenario. Need to do some serious research. You'd think it's just flow vs. inverse flow but pressure does introduce more energy and heat.

s vier
08-27-2018, 07:49 AM
The secret to unlocking hidden power lies within the details of Apeís diagrams; most importantly........

The bee....

08-27-2018, 09:09 AM
The dyno results were a sting in the tail

Ape Factory
08-27-2018, 08:05 PM
LOL, you guys are awful. Keep day jobs :)