Landracing Forum
Tech Information => Technical Discussion => Topic started by: fj1289 on August 04, 2014, 07:29:10 PM
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What are the thoughts on running with or without airfilters? It's an older air cooled 4 cylinder motorcycle with partially enclosed bodywork. Converted to EFI but no airbox. Filters are dual UNI foam pods.
Thanks,
Chris
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I think the general feeling is to run some sort of filter. Racers have reported engines ingesting quite a bit of salt dust, especially if the intake is a direct path with no air box or ducting that might pickup clean air in some sheltered location.
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Smokey Yunick said "Only 2 vehicles don't need air filters, planes that never land, and ships that never dock."
:-D
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No filters were used on the Triumph for the first few years. The pistons and bores were scratched up pretty bad when the first tear down was done. Small oiled gauze pod filters were used on motor #2. They did not work either. Feelings are the filters were very close to the carb intakes and the pulsing air pressure pulled the salt through them. Motor #3 has big oiled foam pod filters. No problem. The pistons and bores looked perfect during the last tear down.
Vizard, in his book "how to Build Horsepower" has formulae for sizing air filters. Years ago when tuning desert racing bikes we learned the least restrictive air filter is seldom the best. Usually what works better are some of the more restrictive ones that are adequately sized. The filters feed intake tracts with valves at the ends that are closed most of the time. It does not take a huge filter to be more than adequate.
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Thanks all - filters it is then!
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FJ, we have used un-oiled K&N filters on the Bockscar and bike with success. We knock the salt out after every run. The filter also helps "straighten" the air as it makes its way into the engine.
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I figured this question has been asked before. Something we are trying to figure out before the car goes out.
this set-up cost us 80hp:
(http://i201.photobucket.com/albums/aa150/Sleepercp/Car%20Pics/Airbox1_zps7e0815cc.jpg) (http://s201.photobucket.com/user/Sleepercp/media/Car%20Pics/Airbox1_zps7e0815cc.jpg.html)
ended up with this set-up with wire mess screen to keep the birds out :
(http://i201.photobucket.com/albums/aa150/Sleepercp/Car%20Pics/mkviiiinstall_zpsf9de80d9.jpg) (http://s201.photobucket.com/user/Sleepercp/media/Car%20Pics/mkviiiinstall_zpsf9de80d9.jpg.html)
(http://i201.photobucket.com/albums/aa150/Sleepercp/Car%20Pics/Airbox1_zps6a6fa4c4.jpg) (http://s201.photobucket.com/user/Sleepercp/media/Car%20Pics/Airbox1_zps6a6fa4c4.jpg.html)
I think it's fine, dad wants to run a filter. I'm thinking I can find some foam from an Uni-air filter or something like that and wrap it.
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Joel SR. will never notice if you tell him you have a new @$%# &*($# filter thats almost invisable.
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you are probably correct ..... :-D
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Picture 2 looks like the filter is inside the mesh(?).
I think the turn was the culprit, but what do I know.
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If those are self tapping screws replace them with rivets. Your and everyone else's tires will thank you.
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If those are self tapping screws replace them with rivets. Your and everyone else's tires will thank you.
rivets were the first choice.. ran out of time.
Will look into replacing them.
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Picture 2 looks like the filter is inside the mesh(?).
I think the turn was the culprit, but what do I know.
no filter just the mesh
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Yep that sharp turn with no guide vanes or anything to help turn the air is probably the primary culprit for the power loss.
If you can't find foam that works you might try a loose fabric like a cotton tee shirt sewn into a sock that just slips over the screen then oil it like a K&N filter.
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Here's a tip.
Take it or leave it.
I may not have credibility here because I'm in Africa and don't have a car that runs.
Get this material and use it as an air filter. Cheap!!!
Try it and tell me.
Vacuum bagging breather layer available at companies that sell composites.
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A screen cuts air flow by a bunch. Remember, no air flows through the metal part. A flat cloth cover only has X number of square inches of area. A pleated cover is better. On home A/C systems most come with a 1 inch thick pleated filter. On a commercial system they recommend at least a 2 inch pleated filter to keep from Evap. freezing. When we built our filter for the lakester we called K&N and they said that the 10X12 1 inch filter that we had picked was way small even for our old Buick. I think the number they came up with was we needed something like 200 sq. inches.
Doug :cheers: :cheers: :cheers:
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On Tuesday night the engine made 21 psi boost without an air cleaner or screen.
On Friday night with the screen it made 21 psi boost at the same rpm.
when we go to Westech we'll try a couple things to see what happens.
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maybe a shop vac pre-filter:
(http://i201.photobucket.com/albums/aa150/Sleepercp/Engine%20stuff/shopvacpre_zps23269823.jpg) (http://s201.photobucket.com/user/Sleepercp/media/Engine%20stuff/shopvacpre_zps23269823.jpg.html)
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You can put a spigot on the manifold between the filter and the carb. Put a clear piece of hose on the spigot with the end in a can of water. The vacuum in the manifold pulls the water up the tube when the engine is running. Restrictive air filter systems pull the water up higher.
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A carb guru told me that on a Holley 4150 they saw a big CFM loss till they put on a 14" W by 8" tall high flow type filter. So if you have a plenty big carb maybe a K@N with there trick top that is also a filter? I'd tell you the guru's name but then you'd know what kind of carb I'm running and if I go real fast, well you know.....
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A carb guru told me that on a Holley 4150 they saw a big CFM loss till they put on a 14" W by 8" tall high flow type filter. So if you have a plenty big carb maybe a K@N with there trick top that is also a filter? I'd tell you the guru's name but then you'd know what kind of carb I'm running and if I go real fast, well you know.....
Well since we aren't running a carb .......................... :roll: :wink:
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It's super common for the higher hp turbo engines to gain 50-100hp by removing the air filter from the turbo inlet.
From my experience, your "plenum" right on the turbo inlet is actually worse than having nothing at all on there...
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It's super common for the higher hp turbo engines to gain 50-100hp by removing the air filter from the turbo inlet.
From my experience, your "plenum" right on the turbo inlet is actually worse than having nothing at all on there...
How concerned would you be about running an air filter at all ?
I'm not all that worried about it, but my father is.
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I would bet that the 100k RPMs of the turbo impeller will make quick work of any salt particles that MAY be picked up in the air flow. A giant blender with unlimited HP! !!!!!!
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I'm seeing apples, bananas, strawberries. :-D
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Salt particles do lots of damage.
Doug :cheers: :cheers: :cheers:
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The salt particles will also make quick work of the edges of the inlet impeller.
At 100k rpm the outer edge of a 2 inch inlet impeller is moving at 873 ft/sec or close to 600 mph.
Small water droplets in the air stream will eat up a turbo impeller hard salt crystals will sand blast it and destroy the outer edge of the impeller very quickly.
This could lead to imbalance and catastrophic failure of the turbo which typically results in the engine eating some of the shrapnel.
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Salt particles do lots of damage.
Doug :cheers: :cheers: :cheers:
certainly they can... depends on where the air is coming in I'd think. With the N/A engine I don't recall any salt sitting behind the radiator or on the front of the engine where the intake is now. I'd think a wrap or the Shop Vac pre-filter foam would capture particles that could damage the turbo. I could be wrong though.
anyway we'll have time on the chassis dyno to figure a few things out. So an A/B test or two will be in order
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There is a common misconception that any air filtration system will cost power from restriction to the airflow path into the engine. The filtration system does not need to be a power robbing solution however with most folks wanting the "quick and easy" off-the-shelf answer will probably make the wrong choice in air filtration. :-(
The air filter system can be one way to smooth and straigten the air going into the engine. Sorta like an oil filter - surface area might be something to look at in order to decrease the potential losses. It depends on the media and the flow rate. :lol:
Don't know about you, but the care and effort put into prep of cylinder heads, seats, and cylinder walls encourages me to protect the stuff as much as possible. :?
Regards to All,
HB2 :-)
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Even a low buck effort has a huge investment in time and energy. Think of salt crystals as granite rocks, because the damage would be the same. The dust at El Mirage is as abrasive as it gets and passes through a out of filters.
The wire mesh works for birds and boulders. Might as well run nothing. You run the heads on a flow bench, run the filter setup too. The flow through a filter can be calculated. Running a tiny filter gets you tiny results. Just because you don't have room for a proper filter means you still have work to do.
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Mark flowbenched my 45 DCOE Weber both with and without a K&N Filter. I don't recall the numbers, but the numbers were insignificant enough to warrant retaining the filter.
(http://i1267.photobucket.com/albums/jj549/fordboy628/100_2745_zpsc6ebe8dd.jpg) (http://s1267.photobucket.com/user/fordboy628/media/100_2745_zpsc6ebe8dd.jpg.html)
(http://i1267.photobucket.com/albums/jj549/fordboy628/100_2747_zps2a1c7ce3.jpg) (http://s1267.photobucket.com/user/fordboy628/media/100_2747_zps2a1c7ce3.jpg.html)
Conversely, when we put foam filters on the air horns, at 28 inches of water, it darn near sucked the filter into the carb.
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It's super common for the higher hp turbo engines to gain 50-100hp by removing the air filter from the turbo inlet.
From my experience, your "plenum" right on the turbo inlet is actually worse than having nothing at all on there...
How concerned would you be about running an air filter at all ?
I'm not all that worried about it, but my father is.
I would run a filter at least untill you're to the point where you're usilizing all the power you can get. It'd be better to up the boost 3-4psi and run a filter in my mind!
Maybe Rick Mc Inroy will chime in here with what he saw in the intake manifold plenum? His car has a forward facing hood scoop that ingested salt last year. He says that he could see the salt coming up off the front left tireand crossing the hood due to the crosswind...
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There are too things to worry about with air filters. One is having them large enough to not cause a restriction. The other is having them big enough to filter correctly. My experience says it i good to discuss both of these aspects with the filter manufacturer.
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Today I looked at my notes. First I ran open intakes and there was a lot of scratching on the piston skirts. Next, oiled gauze pod filters were tried for the second build. They were pretty small and they did not filter very good. After that oiled foam filters were tried. Vizard's 3.5 square inch filter surface area was used to calculate the horsepower they would support. It was 250 HP per filter and the bike made 46 per cyl. Scratching was reduced on the skirts. Finally, some big oiled foam filters were installed. They support 322 HP each according to Vizard's flow value to not cause restriction. The skirts have no scratching and the wear surfaces and nice and shiny and polished. This equates to about 1.8 engine HP per square inch filter area.
Bikes have short and open intake tracts compared to cars and there is pulsating flow at the bell mouth inlet. My guess is the big filters are needed to compensate for this. I really do not know why, but the big filters are needed to keep the salt out of the engine.
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I think it depends on where the inlet air is located on the car......
None of these cars use air filters........
Many others I can show but the point is..... it depends on the car & where the inlet is. YMMV
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About ten years ago Gary Vail spun the Geisler, Vail and Hizer Studebaker and afterwards found salt in the combustion chambers. They were running a v6 Buick with spril dominators and they were running a low snout scoop on the hood which followed the contour of the hood.
Apparently the spin kicked up enough salt that it was at least 30" +or- high.
Why was the motor still running? You will realize why the first time you spin......................... :-D
One Run................
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The scoop on our car in my avitar picks up Salt thrown up by the front tires. We built some Salt deflectors to direct the Salt higher up and away from the inlet but we were told that they couldn't be used because the car is running as a lakester. Another problem was on a damp track they throw up a Salt mist that drys instantly on the canopy and makes seeing the mile markers impossible. [ask me how I know that] :cry:
Doug :cheers: :cheers: :cheers:
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I always thought of an air filter as a life extending product. Kind of like eating healthy and not smoking. But since race engines run hard and fast, and almost always get rebuilt at ridiculously short mileage intervals, then why not let them enjoy a bacon cheeseburger and smoke a few while they are doing their business?
So, on my street cars and push truck, definitely. On my race engines? no, I just make sure the scoops are pulling clean air and no salt or dust gets in under normal operation. I also try to make sure no big chunks of stuff can get into the turbo impeller. So far I have never had to replace a turbo because of compressor damage. I always ruin them long before they get to that point by ejecting hot valve parts through the exhaust side first. :-P
Also, keep in mind that we run alone, never in packs and never directly behind another vehicle. That is the condition where lots of crap gets kicked up and ingested by the trailing car. I would definitely run a filter on any engine where you may be following another vehicle.
Also, I run a turbocharged, inter cooled engine. My complete intake tract is a convoluted set of passages and tanks and what not. It would be very difficult for a solid mass of any size to make it to the engine. N/A guys have a different set of conditions.
Just my opinion, YMMV
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I guess it's time to offer this information. It's about our motorcycles - and the proclivity of salt to get into the air intakes.
And the intakes on both the 12 and 14 are mounted above the front tire and just behind a vertical plane of the front of the front tire. In other words, the salt has to get thrown forward as well as up to be in the right place for ingestion by the time the scoop is at that point.
Another way to say that is the salt manages to get to the vehicle - the scoop - far sooner than the scoop mounted as on Doug's car, for instance. Just 'cause your air intake is just about even with the front tires won't protect it from getting salt in it.
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I have a couple of good ideas I'm working on that should work without having to rebuild the front of the car. It's amazing to run out of space after putting a 4 banger where a v-8 used to sit.
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I wish K&N had a CFM rating on their filters.
Thinking about building the air box we need then rearranging water line, radiator brackets, and (the big thing ) moving the intake manifold plenum. It will be some work, but shouldn't limit ourselves to what's there to work around. build the air intake system to what we need and then make the other parts work.
Would have our fab guy build a mounting base then sandwich 2 of these 5"x9" filters then either use a solid lid to hold them together or one of the K&N XStream air flow tops the 9" diameter one.
http://www.knfilters.com/search/product.aspx?prod=E-3650&pkid=1618190&rw=1
I'd think allowing the turbo to feed air from all sides ( filters will be horizontal mounted to the compressor) it wouldn't lose much and having basically 10" long by 9" dia should allow all the cfm needs it would have.
it will mount just like the screen
(http://i201.photobucket.com/albums/aa150/Sleepercp/Car%20Pics/mkviiiinstall_zpsf9de80d9.jpg) (http://s201.photobucket.com/user/Sleepercp/media/Car%20Pics/mkviiiinstall_zpsf9de80d9.jpg.html)
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After K&N told us we should have more filter area than the 10X12 filter that we were using we built this box. One 10X12, two 4X12's, and two 4X10's. Seems to work and keeps the Salt out.
Doug :cheers: :cheers: :cheers:
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After K&N told us we should have more filter area than the 10X12 filter that we were using we built this box. One 10X12, two 4X12's, and two 4X10's. Seems to work and keeps the Salt out.
Doug :cheers: :cheers: :cheers:
how many cubic inches are you feeding and hp level?
the other option is something like you did with 4 8x10's and an end cap
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After K&N told us we should have more filter area than the 10X12 filter that we were using we built this box. One 10X12, two 4X12's, and two 4X10's. Seems to work and keeps the Salt out.
Doug :cheers: :cheers: :cheers:
Nice :cheers: :cheers:
(http://www.landracing.com/forum/index.php?action=dlattach;topic=14244.0;attach=47878;image)
Do you have any more pictures of the other side and such. I'd like to see how that is connected to the compressor. Thanks,
Sum
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I don't, but it's not totally sealed up underneath. On the compressor we have a 4" by 90% elbow that just sticks through a 4" hole in the bottom under the filter pac. Probably could have put a little stub on the bottom and slid it over it but it is kind of a pain to get on any way and we were just trying to stop the big pieces of Salt from getting in. It seems to work as the Salt just lays on the top filter now.
Doug :cheers: :cheers: :cheers:
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I don't, but it's not totally sealed up underneath. On the compressor we have a 4" by 90% elbow that just sticks through a 4" hole in the bottom under the filter pac. Probably could have put a little stub on the bottom and slid it over it but it is kind of a pain to get on any way and we were just trying to stop the big pieces of Salt from getting in. It seems to work as the Salt just lays on the top filter now.
Doug :cheers: :cheers: :cheers:
Thanks, that helps,
Sum
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I wish K&N had a CFM rating on their filters.
CFM is in the secret [Vizard] recipe at filter selection: http://www.knfilters.com/filter_facts.htm#MYTHS
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Woody and All that like this kind of stuff,
I think you are mistaken about the secret recipe stuff and to whom to attribute same. :roll: The correct guy would be a guy named Bernoulli :-D and the issue of dynamic pressure. Then if one considers the filtration part (loss of head) perhaps Darcy-Weisbach would be a better inclusion. Of course all those guys came along quite some time before David don't you think? :-o
Over and over again: The use of filtration media does not need to cause much airflow loss if the correct media is chosen along with sufficient area of that media. :lol: 8-)
You can now return to your regularly scheduled programs. :cheers:
Regards to All,
HB2 :-)
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Harold, someone still has to convert all that "chalk on the blackboard" into useful "recipes"! :-o
Thanks to you and David for that! :cheers: :cheers:
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Ah - a close re-read and BINGO - the devil in the details -
We're all talking about air filters, but Harold let slip a distinction in his earlier post -
There is a common misconception that any air filtration system will cost power from restriction to the airflow path into the engine. The filtration system does not need to be a power robbing solution however with most folks wanting the "quick and easy" off-the-shelf answer will probably make the wrong choice in air filtration. :-(
HB2 :-)
And seeing as K&N - or any manufacturer of filters - has little ability to control how their filters are used . . .
I wish K&N had a CFM rating on their filters.
. . . any information they could glean with a flowbench would be dependent on the housing and system the filter was incorporated into.
Woody, I've been checking out your pages on airflow - scoops in particular - and what becomes clear is that intake - regardless of whether or not filters are involved - needs to be looked at as a complete, integrated system.
The evidence Vizard has put forth is that a properly sized and designed filter can produce no restriction, but Woody's work indicates that such a filter would need to be something well integrated to be effective.
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I wish K&N had a CFM rating on their filters.
CFM is in the secret [Vizard] recipe at filter selection: http://www.knfilters.com/filter_facts.htm#MYTHS
I was just taking a wild-as s guess as to the needed filter size based off CFM requirement. I was just using "round" numbers:
180" x 9,000 rpm/3,456 = 469 cfm
at 20 lbs boost the engine "thinks" it's 2.4 times bigger than it is: 2.4 x 470 cfm = 1,128 cfm.
looking at it another way: if we are making 900hp ( rounded up numbers) with a BSFC of .55 we are burning 495 lbs fuel an hour. At an AF ratio of 11:1 we would be burning 5,445 lbs air an hour or 91 lbs air per minute. 91lbs/.0807( weight of a cubic foot of air) = 1,124 cf.
So my wild a ss guess was kind of close. We need at least 1,125 cfm to feed 900hp.
A 9" diameter round filter has a circumference of approx. 28" 28" x 5''(H) = 140 x 2 (filters) = 280 sq. in. of filter area to feed 900 hp.
If I use the K&N formula where A= filter area and CID x rpm/20,839 =A I'd get 187" filter area.
180" x 2.4 ( boosted engine) 432" x 9,000 / 20,839 = 187" filter area. So my filter area of 280" would have a minimum of a 50% over-size factor in it.
I think that all works out ..... ???? :?
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Howdy to All that like this kind of stuff,
Indeed the system is the key in all this stuff as many components have to work together. It is the system that should be integrated into a design. Attached is a pic of a roadster that has gone through many iterrations but the air supply system has remained constant. Now the thing runs as a D class (smaller engine). The package shown does include air filtration and adherence to Mr. Bernoulli's directions relative to airflow as a system.
Hope All that go to the upcoming meet have salty success. :cheers:
Regards to All,
HB2 :-)