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SmartieParts

451 Aftermarket Air Intake Performance Test Results

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On this Self Promotion discussion, there was question as to the actual performance characteristics of the Stainless Steel Air Intake with K&N Performance Air Filter shown below.

post-8-1216531651_thumb.jpg

The questions brought up were valid, but all we were doing was pitting common mis/pre-conceptions against the manufacturer's claims... neither of which I have any faith in. So as always, I decided to put it to real world tests.

The platform for any of my performance tests centers around the G-Tech Pro RR accelerometer. This unit can be calibrated to get very accurate results, but even uncalibrated it still provides relevant relative results. For this test, I did not calibrate the unit beyond the basic setup routine. So the numbers provided can't be used in their absolute meanings. In other words, 45HP or 54HP or whatever... the number is meaningless. Still, we can say 54HP is 20% higher than 45HP. Using this methodology, we can confirm or refute the manufacturer's claims of performance increase.

Before we get to the performance results... I do want to say they did a great job of making this thing look good, and sound great! Even if you aren't going any faster - you certainly sound like you are :)

The manufacturer's claim:

The maker of this little beauty says you'll see a 8HP gain at around 5000rpm. That's not comparing peak performance though... their chart shows a peak difference of 69.84HP vs 66.62HP. They got that on a static dynomometer or "rolling road". A lot of car folks treat dynos like fanciful metal gods, but they don't provide real-world results. Air resistance is the main thing dynos ignore, and that can make a big difference out on the road. As well, there are different ways to measure and report horsepower. So I never put much stock into published dyno results. So really, even if we see no gains today on the road, it doesn't make them liars. Its hard to compare dyno results to accelerometer results... but we'll try.

The dyno's stock run gave them a peak HP of 66.62. The modified run saw 69.84 HP. That's a gain of 3.22HP or 4.83%

Our test results:

I had hoped to post the G-Tech graphs here, but the PASS software version I have won't run on Vista so I have to take the readings from the unit itself. If there's any question, bilgladstone was with me the entire time and saw the results and should be able to confirm what I'm saying.

We did the runs with the pedal to the floor and the transmission in Auto. This may not yield the highest HP values, but it does take out the driver skill variable. We did a stock run down a highway and then another run back. Then we did the modification and repeated the run again from/to the same points. Because the terrain isn't flat and level like a drag strip, it was best to do the run in both directions and average the two. Ready for the results?

With the stock setup, the peak HP one way was 45.4 and the other way was 48.6 for an average of 47.0.

With the modified setup, the peak HP one way was 51.9 and the other way was 52.7 for an average of 52.3.

That is an increase of 5.3 or 11.3%! More than double the manufacturer's peak performance claims!

Again, remember my unit wasn't calibrated so the 5.4HP gain is meaningless, but the 11.3% HP gain is accurate. So if we believe the data, and we believe smart's claim that the smart gets 70HP, then I think we can safely say that with this mod, the car would produce approximately 78HP (70 + 11.3%). Interestingly enough, that's 8HP... exactly what the manufacturer claimed in the first place.

Now, many of the pundits were asking about AIT (Air intake temperatures) with the theory that colder air is required to increase performance. Well, I think we've proved that not to be true. Using a Scangauge during all the runs, my co-pilot (Bil) noted an increase in AIT when using the mod compared to stock. The fact we saw considerable gains in HP while also seeing an increase in AIT shows that it is not as simple of an equation as some people think. Either AIT does not relate to performance as speculated, or increased airflow makes a larger difference then the temperature does. In either case, its hard to refute the performance gains regardless of why they exist.

Overall... I'm impressed. It looks great, it sounds great... and it performs great. Other than some scraped knuckles (Bil obliged so I didn't have to) it was relatively easy to install - certainly not rocket science anyway - and the kit comes complete with everything you need. I do have some recommendations to the company for design improvements, but I think they've got a winner already.

Bil did make a little movie of a run so we could show off the impressive sound, but I'm not sure it really does it justice. If people do want to see it, I'll need a volunteer because I know next to nothing about video editing and its far too large to put up here. It needs to be edited as its far longer than it needs to be. I can provide the raw file in MPEG format if anyone cares. However, I can't really say its worth it - the sound on this little point-and-shoot sucks and its the sounds we were hoping to demonstrate.

Any questions about testing methods, or the results, or anything else... discuss away! Anyone with sales related questions please ask in the Self Promotions thread so we can keep this thread about the modification and performance.

- Steven

ps. Thanks a lot to Bilgladstone who donated time and effort into the testing. He pretty much did the install for me while I watched :) And he manned the Scangauge so I could keep my eyes on the road.

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Bil just emailed me this from an online source:

Cold air intakes will produce more power, and will save gas if the engineoperates only at Wide Open Throttle.However, under 90% of driving, Warm Air Intakes are more efficient becausethe engine is throttled and under less than full load. WAI does two things:1) Fuel evaporates more quickly, increasing combustion speed. Fast burnengines improves the amount of pressure generated and expansion workavailable for a given amount of fuel.2) With oxygen sensors, engines run at stoichiometric air/fuel ratios. Forany given amount of fuel, a corresponding mass of oxygen is admitted. WAIlowers the density of air, meaning that a higher volume of air must be letinto the engine for a given fuel input. So with WAI, the throttle must beopened further for a given output, and this lowers the "pumping" work ofpulling air past the throttle.

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Another preformance note:0-60 time with stock setup was 14.599s and with the mod was 13.207s not bad!within that, the 40-60 time was 7.550s (stock) vs 6.322s. That's a great indicator of passing ability. Over a full second shaved off there!1/4 mile times: 19.801s @ 69.30 MPH (stock) vs 19.226s @ 74.97 MPH (modded)Also, I have torque data. 45.9 ft-lbs @ 4694RPM stock vs 50.4 ft-lbs @ 4544RPM modded (again, not calibrated so pay attention to the 9.8% increase instead of actual numbers)

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Not all roses. I nearly forgot to mention the downsides.#1 - the install was fairly easy, but not as easy as their instructions seem to say. There are a couple of hints they could have provided that would have saved a few swearwords and a bit of skin. We were able to figure it out, but a little instructions can go a long way. This is minor and easily correctable.#2 - positioning is important. After we installed it the first time and went for a drive, it was making a loud banging noise every right turn as it was hitting the frame. This was correctable by repositioning the pipe slightly. While we got it on the 2nd try, I could see some getting frustrated with the potential trial-and-error aspect of this.#3 - you re-use the existing vacuum hose, but with the new position of the nipple the hose is really a bit too long. They should have supplied a shorter hose better suited for the new position. Not the end of the world - the stock hose does fit - but there's worry that the stress at the nipple may cause the hose to pop off or possibly kink restricting flow. Something to be cognizant of, but not a show stopper. - Steven

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Found this image of the installed kit:

Posted Image

Fair Use Attribution: captured from manufacturer's installation sheet.

:sun:

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The tuning worlds great debate lingers on and on and on and on and on... into infinity and beyond!!!People continually shun my Hot Air Intake on my 1.8T saying that it robs horsepower but repeated dyno runs and real world data using a Vag-Com show that it does indeed make additional hp especially when you start increasing airflow in other areas such as the intake manifold, head, exhaust manifold, turbo inlet pipe, down pipe and exhaust. I have done all those things.Initially I saw a 5% gain on the dyno and a 6% real world gain. Close enough to not matter and in fact could be attributed to change in air pressure outside temp or any number of other variables. Now after extrude honing the head and manifolds. I put the stock intake and associated plumbing back on so I could see just what those modifications attributed to the grand scheme of things and then ran another few runs with the Hot Air Intake. Again noticeable gains but this time in the order of 9%. That can't be written off to just environmental conditions. Again the community moaned and groaned that my findings just could not be accurate and that if I had tried a true cold air intake I'd have seen even greater results. Next came a new turbo , down pipe, larger cat and cat back exhaust. I once again did the back to back runs comparing stock and the HAI. This time I saw a 15% gain showing that the stock airbox was indeed a very large restriction. They moaned more and groaned harder and volunteered a CAI for me to test. So I did... I showed a net loss of 1% ie... so close to stock as to make no difference. They said it was rigged or I was lying. I gave up and just decided that physics are great than man. ;)On a turbo motor it is more important to cool the air AFTER the turbo than BEFORE. The turbo will superheat the air to extrodinarily high temperatures. So high in fact that 10* to even 100* at the intake will have zero affect on that end temperature. On a naturally aspirated car a true cold air intake that can charge cool the air and make more than a couple degree difference will in fact make a substantial difference but only if your computer is programmed to take advantage of both the increased quantity AND increased density. The stock system has a programming wall set up and even if you dumped sub zero air into the intake it won't make a bit of difference since it can't take advantage of the increased density and in fact it may very well actually reduce power because the system can't increase timing enough to burn the fuel properly so you get a computer scrambling to get a complete burn and actually backs things off so now you are getting worse mileage and less power. Obviously not an ideal situation on a daily driver. For daily driving I suggest just getting a freer flowing intake that can increase the quantity but still keep the air warm enough to keep the computer happy. Tom aka Fowvay P.S. I hope this made sense. It's 6:16am and I have been up all night fighting yet another case of insomnia so I may have rambled just a little bit more than usual. ;)

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It made sense but was probably over my head. I just care about the results. Warm air, cold air... I don't care. Bottom line was a significant increase. Why it happened, I suppose I couldn't care less. It happened. - Steven

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It made sense but was probably over my head. I just care about the results. Warm air, cold air... I don't care. Bottom line was a significant increase. Why it happened, I suppose I couldn't care less. It happened. - Steven

It also wasn't supposed to sound anywhere near that smug.... oops. :huh:

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#3 - you re-use the existing vacuum hose, but with the new position of the nipple the hose is really a bit too long. They should have supplied a shorter hose better suited for the new position. Not the end of the world - the stock hose does fit - but there's worry that the stress at the nipple may cause the hose to pop off or possibly kink restricting flow. Something to be cognizant of, but not a show stopper.

I retract this statement. The manufacturer showed me before and after photos showing the bend I'm seeing after the install is very close to the bend that was there originally. I guess I just didn't notice before pulling things apart. The nipple is, in fact, very close to the original position. - Steven

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So the fuzzy summary is +5BHP gain +8lb/ft torque. For a single bolt-on mod I was impressed.

The G-tech "drag race" testing was pretty hairy, especially the second set of runs with the increased power. Whoa Nelly! Brown trousers! :yikes:

In fact, I may have filled my shorts just a little tiny bit.

I think that's what threw me off balance when we did the video-with-sound recording, and I actually fell over! :lol:

:sun:

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Quite a bit louder than I expected! :ohno02:

Imagine the Dbs with a Thorley exhaust on top! :cowboy: B :sun:

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Quite a bit louder than I expected! :ohno02:

Me too! It sounds pretty good. But the nice thing to me is that unless you're really hammering the gas, there is no noticable difference in the sound. Its really only there when you want people to know its there ;) - Steven

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... Its really only there when you want people to know its there...

... or when you need the extra power for passing or accident avoidance!:sun:

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I love the sound! I noticed an increase right away... much smoother in auto mode and faster up hills and sub-2000 rpm acceleration. Just a little more low-end torque and high-end power... it's nice to see some numbers to back it up :) I went to an underground parking lot in town and let it rip in 1st gear... what a noise! Definitely worth the coin for the noise alone :) Long term test to see if it will change my gas mileage at all. A couple of downsides... I didn't tighten the filter enough so I lost it somewhere heading back from the underground parking lot :( and I may have to bend the mounting bracket a bit to stop it from banging against the car around right hand corners. I tried as best I can to move it as far away as I could but it still bangs from time to time... not good for the long haul.All in all, a very worthy product for 451 owners who like noise :D

Edited by Jibber

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Hi Jibber. Bil and I experienced the same problem with the banging on right turns, but after one adjustment (push it into the hole as far as possible and pivot around the bracket counter clockwise a little) it was eliminated completely. You can also attempt bending the bracket a little by hand. The manufacturer has taken notice and is fixing the problem, I think by shortening the pipe slightly.Sorry you lost your filter! It is important that it go on tight. I should go double check to make sure mine's still on there :)It is going to be difficult to do a fair economy comparison... I haven't been able to help myself when it comes to showing off the sound and power :) And when you do that, of course, you are burning more fuel. The question is whether or not it inherently hurts the economy, which I doubt. This particular tank is a lost cause because of the performance runs anyway (I went down 2 blobs in under 100km) so I'll get it out of my system and drive normally after I fill up. I promise. - Steven

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Regarding the noise.It is nice to those that like it, but I want to stress that it isn't obnoxious to those that don't. During normal driving I can't say I hear any difference at all. The power is there when you need it, but its not like you're driving around town blowing people's eardrums all day. Its a good "loud" :) - Steven

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Yeah, I thought the noise was perfect... exactly why I bought the product. The fact that there are performance gains to be had is a bonus IMO. I found that when cruising at highway speeds, you can hear the little engine purring away behind you over the road noise, so it feels more like a proper little sports car rather than a quiet economy bubble car. And the only time when it's "obnoxiously loud" is when you're at WOT over 5000 rpm. Then you get a noise that goes down as one of the top ten sounds I've ever heard any car make :D

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Okay, so for future reference, the RC-2580 K&N filter that comes with the intake isn't ready available at most places that carry K&N filters. Using the list on the K&N website, the RU-2580 is the exact same filter with a rubber top on it instead of metal. Most places carry this one in case your filter goes missing. :blush:

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