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View Full Version : TECH ARTICLE: do intakes lose power? do i need a tune? explained



trinydex
03-21-2006, 12:38 AM
i keep seeing these thread on every board i visit and it's starting to really piss me off cuz all you get is a buncha parrots repeating what they've heard and what these vendors preach. so here's the deal.

volumetric efficiency is volumetric efficiency, if you bolt on a part that increases horsepower... your horsepower will increase. you don't need a tune, you don't need a flash, you don't need ****.

if you want your car to run OPTIMALLY, as in the most efficiency and hence the most power possible... then you should get a tune, but this is even said for a STOCK car. anything that increases the efficiency of the car will henceforth amplify the power produced and allow you to "tweak" "tune" etc more power out of it becuase it changes the amount of air flow capable through the engine. but the power gain is still there, EVEN WITHOUT THE TUNE.

so this brings us to the subject of intakes. will intakes lower your power? do intakes make power? will my car run ****ty? will i stall? will i mess up my maf signals and stall? etc etc etc.

the answer? the stock intake is pretty good, it's hard to pull power out of an intake mod in a turbocharged car anyway. that's fact and MOST OF THE TIME people are mislead into thinking that they SHOULD get power from an intake for two reasons: the first is naturally aspirated cars get power from intakes but that's cuz they don't have an air pump doing the air sucking, the engine is doing the air sucking, hence less restrictions in front of the engine means more power. two, older turbocharged cars came with very restrictive intake tracts and filter setups, replacing those intakes made power.

the verdict? the stock intake is good enough. it's heavy, clumsy looking, gets in the way of everything under it. but it works PLENTY FINE. there's no magic in the tuning, you're not gonna see 10hp from throwing it on, you might not even see 10hp from tuning with it on. until you reach over 350, you can't complain about it, when you finally get around to squeezing every last little hp out of the car on pump gas... you can consider one.

will it make your car run like crap and make you lose power? run like crap... did you install it right? and if after that is out of the equation you can only speculate like the rest of us whether or not your intake makes your car run like crap, for me personally, it's fine (why do i have an intake? cuz it's lighter). will you lose power? prolly not, but the maf is a sensative little turdstar and it hates you and it hates you more when you mess with its pipes and it hates you most when you start trying to flow 400+hp through it. all this of course can be remedied by a tuning device, but why use a tuning device to work on a car that doesn't need the piece that you are tuning for? hey... sometimes you gotta do what you gotta do, and if that's your bag of tricks, then proceed.

so why does tuning usually get you more power. i mentioned already that when you put on a modification that changes the volumetric efficiency of the engine then the flow capacities are changed and you can exploit those changes with a tuning device.

running leaner makes more power but too lean is too dangerous. running more timing advance makes more power but too much timing is too dangerous. bolting on mods affects the a/f ratio some, but leaves the timing alone. however a more efficient machine will run cooler allowing for more SAFE timing advance. so where else does the power come from? many times it's more air flow, reduced restrictions that before robbed power. the more air flow must be matched with fuel before optimal power is realized.

now it seems i've contradicted myself because i said running lean makes more power, but then i cited that the increased air flow requires a match in fuel. well if you have too lean you get a lil knock and all your timing goes away cuz any good engine management including the stock ecu has provisions from removing timing advance as a gesture of safety.

so what about more air flow? well your boost will increase or it will hold out longer. what about removed restrictions, well your engine works less against these "loss" forces and hence can pump out more air more efficiently.

examples, cams... increase air flow through the engine. cams give you more power in this way. exhaust removes a lotta restrictions out the back of hte engine. so the pumping losses experienced by the engine are less, netting you power.

what about something like ignition amplifiers? good question, this actually doesn't affect the ve of the engine, this actually makes the engine more efficient at combusting the fuel, not pumping air, so it's more of a usage efficiency rather than a flow efficiency.

i'm sure this is not new to anyone, but i'm putting it all in the same place and for goodness sake please no more of those threads.

related threads. flow limitations

http://www.socalevo.net/forum/index.php?topic=28847.0

temperatures

http://www.socalevo.net/forum/index.php?topic=30802.0

trinydex
03-21-2006, 12:42 AM
this is a reply in the original thread.


But it does.

A MAF requires laminar flow for accurate reading.Â* The factory airbox is designed to offer good flow characteristics while minimizing noise and turbulence.

When one bolts a conical filter straight to a MAF, this tends to disrupt the quality of airflow.Â* Instead of a steady stream of air passing through the MAF, there are erratic pockets of high and low pressure, just like one experiences when flying a plane through a storm.Â* This makes the MAF signal erratic, which compromises its accuracy, and therefore the accuracy of metering fuel at WOT, where the ECU looks *only* to the MAF for fuel metering info.

I've observed this phenomenon over the past 12 years in which I've been tuning MAF equipped cars.Â* Some intake kits will foul the airflow more than others, depending on the type and shape of filter, distance of the filter from the MAF, and even location/orientation inside the engine bay.Â* This being the case, it's *always* a good idea to include a dyno tuning session following installation of an intake kit, and install the kit with other mods that also require dyno tuning.

And be advised that intake kits that are advertised to add XX hp to a stock EVO may be able to do so - purely because they cause the MAF to misinterpret the signal, resulting in a leaner mixture (and factory cars run rich).Â* Obviously, an EVO that is already tuned may experience no gain, or even a loss in power without further tuning.

more info about intakes


An EVO friend and I did a little experiment at work today. We’re both engineers at a company that makes OEM automotive parts, including intake air systems. Utilizing the flow test equipment normally used to test OEM designs, we evaluated the stock EVO intake (w/a K&N drop-in panel filter) compared to the Buschur filter. Both setups had the stock MAF bolted on.

The stock intake was tested in three ways: normal, without ram air duct/scoop, and without any filter.

Both the K&N and the Buschur filters are used, but have been fairly recently cleaned.

Pressure drop is reported in inches of H2O.

Results:

[email protected]@400cf m
Buschur....................5.26................... ......6.46
OEM........................13.36.................. .....17.22
OEM (no filter)........9.24.......................not tested
OEM (no scoop).......9.76.......................not tested

The Buschur filter shows a whopping 61%-62% reduction in pressure drop compared to a stock system w/K&N panel filter!

The stock system can flow almost as well w/out the scoop as it does with no filter at all! (a 27% improvement over stock) Of course, you would be sucking hotter air, but it definitely means that there is power to be gained by increasing the area of the scoop (add another scoop on the other side of the airbox, perhaps?).

The Buschur setup was very, very loud during the test (almost painfully so). The MAF itself was generating a high pitched whistle noise. The stock setup does a very good job dampening this whistle, which gets about twice as loud when you remove the scoop.

Anyway, we were hoping to finally put to bed the constant argument of the stock airbox being better than aftermarket units. Of course, there are other considerations (smooth airflow into the MAF to get stable mixture readings, hot air underhood, etc.), but in terms of overall flow, the stock system isn’t nearly as good as the Buschur unit.

Now Mr Buschur, feel free to send us a free part or two for objectively proving the quality of your parts. We were thinking a pair of LICP’s would be nice! ;)


Here are the results of my intake air temp study, stock box (w/K&N drop in) vs. Buschur dry white filter (stock MAF pipe). Sorry for the delay in posting.

The test procedure:
1.) Precondition the vehicle by driving on the expressway for ~2 miles with no boost. Take exit and stop at car pool parking lot.
2.) Soak in car pool parking lot for 10 minutes, recording data.
3.) Drive off to expressway for ~2miles, accelerating with minimal boost. Record data to observe rate of cooldown.
4.) Change from Stock to Buschur intake and repeat.


Some observations:

- It was ~70F during this test.

- The accuracy of intake air temps in EvoScan was not very good back when I did these tests (version 0.90). Don't get too hung up on the exact numbers.

- Instead of messing around decoding the timebase, I just left 'sample number' on the X axis. The total time is labeled though (10 mins soak, 3 mins cool down).

- At idle, the increase of intake air temp is 3.26degF per minute for stock, vs. 4degF per minute for Buschur. I expected the Buschur to be much faster than stock, but it was actually quite close.

- During later testing, I found that running heavy, WOT boost results in a VERY FAST increase in intake temps.. The increase rate is MUCH faster than noted above... approximately 10degF per second!

- The cooldown rates seem very similar between each intake type. This is expected, since I keep the stock snorkel installed to channel cool air to the Buschur intake.

- With the Buschur filter installed, the intake air temp at idle sways up/down when the cooling fans cycle on/off. This makes sense, since the cooling fan is blowing hot air at the intake. I doubt there is any real problem with this.. it's just interesting to see. The stock setup doesn't do it because the snorkel is forcing the air to be drawn from forward of the radiator assembly.

- I tried to upload the raw Excel graphs/data, but the files will only compress down to about 500K, so I had to convert it to jpegs. Sorry.


You can reach your own conclusions about what this data means. Here's mine: The very minor difference in the rate of intake air temp increase between the two is not enough to worry about. Since the intake temp can jump up so dramatically fast during boosting, the extra 0.7 degF/min during idle is nothing to worry about.

FWIW,

Rob

trinydex
03-21-2006, 12:47 AM
those are the cliffnotes by the way, if you don't wanna go look for the info... it's all there for you.

leaveit2bevo
03-21-2006, 02:19 AM
I have seen gains from intakes just some intakes suck... RMR and the typhoon ive heard just balls out suck. My cold air intake seems to do well.

wj4
03-21-2006, 02:24 AM
i have an aem intake, i felt no gain at all...and i dont have any ideling or stalling issues as well. to be honest, i bought it so i can hear my bov more hehe. it was only $40 so i didnt really mind

reborn
03-21-2006, 08:24 AM
If you guys want to know which intakes make the most hp for your buck there was a back-issue of SCC that dyno tuned intakes(tuned evo of course). Of course, they're not going to be accurate due to lack of airflow but it is helpful if one is in the market for an intake.