Aftermarket Air Filters - any benefits

[burntorange]

RIght I guess im posting this as from the posts i have read on this forum, advice seems a little contradicting, take the below thread for instance.

My question is, is there actually any benefit to a so called "performance" air filter in a  350z or not? do they actually increase power in any way?

 

I have obviously seen it a lot in other cars where people swear by them, but the 350z the crowd dont seem all that enthuised

 

Ill tell you where i am at with current mods

True Dual flow custom exhaust

Japspeed High Flow Cats

H-Dev Plenum

JWT lightweight flywheel and clutch....

 

im waiting to get in for remap now

 

 

Edited April 24, 2018 by burntorange

[longsh07]

I believe general consensus on 350's is that high flow panels like the HKS drop in one are generally better than going full induction kit.

 

350's airbox is very simple with no complex bends or large resonators compared to some cars so no real benefits in replacing other than for sound reasons. 

 

Velocity stack from later model cars also helps if you don't have one as standard.

 

Edit: sorry, in terms of performance you might gain a little with a drop in high flow filter + velocity stack but its unlikely to be much. For the sake of a few quid to get one you can clean as opposed to chuck away, and the possibility of a bit of extra power, they seem worth it in my eyes. 

Edited April 24, 2018 by longsh07

[burntorange]

thanks for the quick reply, so from what i gather, a drop in high flow filter is better than the induction kits, but the high flow panel filters offer nothing but sound over stock paper filters? is this right?

Edited April 24, 2018 by burntorange

[longsh07]

Not quite, sorry if it wasn't clear.

 

Induction kit = more induction sound, likely small gain in top end power but at the cost of low end torque. (general for all indication kits on most cars I believe)

 

Drop in high flow filter = small gain in power without loss of low end torque. Can be cleaned rather than binned at service time. 

 

Velocity stack = modification to airbox to improve smoothness of airflow. Fitted as standard to later model 350s but can be retro fitted. Should help pick up a little extra power but again, not much.

 

Hope that helps

[burntorange]

Ok so now im following.....so another question in the mix then whilst we are at it,......foam style drop in air filter like pipercross vs a drop in k&n filter.....any benefits of either?performance wise, longevity etc

[veeg33]

Did a simple test (3 maps) on dyno a few years back - (Map 1)Used drop in filter (Blue Print) as the base map, (Map 2) new HKS hybrid high flow filter (2 BHP gain), (Map 3) filter completely removed (another 1 BHP from map 2). Assumptions made: All 3 runs are on the same condition and dyno is mapping consistently throughout the test. As an engineer, i would at least test each condition twice to ensure repeatability =)  i actually only paid for 1 run but the guys there were interested to see the difference too hence gave me 2 free runs.

 

Since then i just put any drop in filter as long as they filter the air going into my engine. Either Blue Print or Mann filters, around £8 each per year

 

 

Edited April 24, 2018 by veeg33

[longsh07]

Much of a muchness really. There may be fractional difference between them but your not going to notice it. 

 

Personally I tend to stay away from filters that need oiling. HKS is foam style, give it a wash and let it dry out thoroughly and it should last just as well as any other type.

 

Edit: there you go, as @veeg33 says

Edited April 24, 2018 by longsh07

[burntorange]

so basically, nothing to shout home about between a standard paper replacement vs a reusable high flow filter and less hassle i suppose as you havent got to clean them either.

 

This explains why there isnt much of a rage about how much performance a particular air filter has added . well hopefully this should clear things up for others thinking the same thing

[Foo56]

I've been looking in to this - Seems that long tube intakes can give benefits but they need to be mounted in such a way as to maximize the amount of air-flow. Also apparently can suffer from heat-soak so heatwrap would be advised.

 

I've had mixed reviews and advice but decided to go for long tube cold intakes before I get mine remapped.

[StevoD]

Mine suffers massive heat soak seeing intake temps almost triple after a few pulls so avoid anything thats metal And Not coated as an intake 

[Bakkums]

Blue line is stock air flow

Orange line is with Mishimoto

 

The air flow is from the MAF from the 350z, so there was a good gain over stock. Don't know what a drop in does, but the difference would be smaller.

Edited April 24, 2018 by Bakkums

[StevoD]

2 minutes ago, Bakkums said:

Blue line is stock air flow

Orange line is with Mishimoto

 

The air flow is from the MAF from the 350z, so there was a good gain over stock. Don't know what a drop in does, but the difference would be smaller.

When this was taking place was the bonnet up? 

[Bakkums]

No, it was on the road so the hood was closed.

 

I started with this one, this was stock filter vs no filter, only a panty hose for some testing only.

(The orange line is with only a panty hose, the reason it was worse in the middle of the graph was because the afr was way to lean)

 

 

I started with some changes to the car. First was a plenum spacer,  second was sport cats and found out that the changes weren't as good as I hoped for. Thought maybe it's the filter/Inlet and then found out that the stock filter was a big restriction as you can see in the above graphic.

Edited April 24, 2018 by Bakkums

[longsh07]

That's interesting, how does this translate to power / torque gains/losses with standard map? Were you able to check this at all?

[Bakkums]

I have the uprev tuner, when I change something to the car I'll drive a bit to warm the car up and log it. Then change everything so the afr is spot on. 

 

My log file contains:

- afr

- rpm

- air flow

- nock

- and some other useful stuff

 

So the first time I changed something the car was already lean. This is most common when modding 350z.

[longsh07]

Probably getting a little off topic now but how did the various filters affect the target afr? Id assume that more airflow would cause a lean condition until it's been dialed in properly? I know stock ECU is a 'learning' unit, I assume uprev maps would remove some/all of their learning and use the programmed map table all the time?

 

I'm not hugely familiar with mapping but I get the basic principles of it so you might need to bear with me

[Bakkums]

The uprev remaps the basic table but the ECU will relearn to get as close to the input you've selected.

[longsh07]

TL;DR: 

I've spent far too long on this now and basically gone of a crash course of fluid dynamics 

Q: Do performance filters increase power?

A: Maybe? There are so many factors involved that even if they do, the difference is likely so small, or could be accounted to changes in air quality, you wont notice it anyway . 

 

----

 

Don't supposed you have torque/power figures do you? Only because @burntorange asked about the power increases rather than airflow, though I fully appreciate why this is relevant.

Would be nice to get a solid answer out of this.

 

Anyway, I went away and read up on AFR, torque, horsepower, air flow, etc etc etc to try and help. 

Now if I've understood everything right and we forget all other cars and just focus on the 350Z.

• How much air can fit in one cylinder is always going to remain the same, however the quality of that air will vary.
• The velocity at which air travels into the cylinders will depend on RPM, how wide open the throttle is, intake piping, air filter, and even how the exhaust gasses exit.
• The density of oxygen within the air can change based on air intake temperature / humidity / pressure.
• The 350Z uses a MAF sensor to measure mass airflow (which accounts for air velocity and density).
• MAF sensor produces a specific reading, ECU fires injectors for specific length of time based on this (to add x amount of fuel) to meet target AFR.

Based on that, if you fit a less restrictive filter / intake then the velocity of the air may increase which seems to be the source of any power increase. The MAF sensor then responds to this and injects more fuel, causing the car to run richer and therefore producing more power.

 

This also explains why, generally, induction kits produce more peak power at high revs at the cost of low end torque.

 

To pinch an example I found elsewhere:

If you were to breath through a straw while walking slowly, you'd be able to breath fine. If you then started running while also only breathing through the straw, you'd struggle to catch your breath.

If you were to replace the straw with a larger straw, you'd still be able to breath fine while walking but you'd also be able to breath much easier while running.

Now imagine while breathing through the larger straw, you making a sharp intake of breath (sudden wide open throttle), while the volume of air you receive would be the same as before, the velocity would be a lot slower.

 

To put it into car terms, a less restrictive 'performance' intake means that at high RPM you can breath more easily, but at lower RPMs when you want to accelerate hard (sharp intake of breath), the velocity of the air is going to travel into the engine slower because there is less restriction and therefore less pressure to pull the air along.

 

The venturi effect explains this as velocity must increase as it passes through a constriction.

I believe this is why velocity stacks work so well for our cars  

 

[burntorange]

I know this is digging up this thread a little, but i am curious about about the benefits of a remap. Now from the above i gather they can adjust the afr ratio throughout the whole rev range by way of that basic table. but with a "learning" ECU surely the standard ECU must do some rearranging to make the most of what is coming in right? 

 

I am curious if the stock ECU will make power on its own when it "learns", have people had a dyno before and after a remap, or does everyone base it off what they should of had from stock?

 

I am not trying to avoid a remap here i am just curious as to what happens with the stock ecu when you apply all this stuff before a remap

 

 

[longsh07]

Put simply, the stock (unmapped) ECU tries to keep the power figure at the figure it left the factory with.

 

Unmodified car - will be slightly down on power due to grot build up in the engine, wear, and all other factors that are totally normal as an engine ages.

Modified car without remap - You may have cleared out the cobwebs and opened up the ability to push beyond stock power figure but the ECU will still target and try to stick to stock power figure.

Modified car with remap - You're car can be tuned to produce whatever power level it can produce safely.

 

For example, my 350Z GT4 should have had 300Hp at the flywheel brand.

I took it for a remap at Abbey Motorsport with the following mods fitted. Milltek exhaust, Berk HFCs, plenum spacer (fitted at Abbey), and HKS panel filter.

As your can see from the dyno chart:

• Pre-remap It made 270Hp at the hubs (+35 for flywheel), 305Hp at flywheel - Top right chart / Yellow box.
• Post remap, peak power was pulled down to 262Hp at the hubs, 296Hp at the flywheel - Top right chart / green box.

While I've lost some peak power I've gained roughly 10 ft/lb torque through most of the mid range (bottom left chart) making the car pull really nicely  

 

 

Edited May 3, 2018 by longsh07
Forgot to post image!

[burntorange]

So you lost power???? I dont know if i would be happy with that 

 

whats the "key" to determine what each of those lines represent?

Isnt there a direct correlation between hp and torque.

lose torque, lose horsepower, gain torque, gain horsepower? Now i know that this also depends on the RPMS that you are running and im guessing where "peak" Horsepower is developed in that rev range.

Im trying to figure out how and what the Remap would have changed to decrease top horsepower and increase toque.  I think this is down to moving where the engine makes peak power up the rev range, but the thing im missing is how that was done.

 

 

 

[longsh07]

Quote

So you lost power???? I dont know if i would be happy with that 

I didn't lose it, its still there an could be tuned back in. But peak power is ultimately just for bragging rights. To get the biggest number I'd lose pulling power in the rev range its driven in 90% of the time.

 

Quote

Isnt there a direct correlation between hp and torque.

Yes. HP = Torque x RPM ÷ 5252

 

Quote

Im trying to figure out how and what the Remap would have changed to decrease top horsepower and increase toque.  I think this is down to moving where the engine makes peak power up the rev range, but the thing im missing is how that was done.

More fueling lower in rev range.

More fuel = more torque.

Higher torque x lower RPM / 5252 = lower peak HP than higher torque x higher RPM / 5252.

 

I think that all makes sense 

Edited May 3, 2018 by longsh07

[longsh07]

This is helpful:

 

[burntorange]

Ok, but in that case what not just add more fueling up top too so that you get the best of both worlds more hp and more torque. 

 

Edit. Think ive just got it lol. So you have intentionally lost peak horsepower to fuel the midrange torque... which 350z you go the revup or hr

Edited May 3, 2018 by burntorange

[burntorange]

I sort of feel from what i have read....so please chime in if im wrong...i dont understand why you just dont go for max hp because so i hear max torque normally follows 1 to 2k below peak hp which would be midrange right on these engines??? Hmmm just speaking my mind right now lol