hey guys i have an 96 spyder with the 2.4 do u have any ideas about supin up my engine? i wish dsm just put a 2.0 in the spyders or at least had made the 2.4 a DOHC

 

K&N intake - or eBay cone filter & MAF adapter will probably be your biggest bang for the buck improvement. I put one on the little 1.8 liter in my Expo and it woke the motor RIGHT up!

Cam gear, cam, & headers will probably be your next biggest improvements - though they are much spendier. Yours is non-turbo, right? A throttle body & MAF for a turbo unit might yield some HP too, and they can be had from junk yards.

Just some ideas....

 

So BobC92 here's what I don't understand about those K&Ns. For them to work the factory paper filter would have to restrict the air flow enough to starve the engine at a certain throttle opening. That would suggest the engineers undersized the original filter. Now I know the K&Ns are able to flow more air (and dirt) but does the engine design need more air as the air volumn needed is determined by the engine displacement, flow characteristics, throttle opening and rpm. I guess I can buy the part about the paper filter getting dirty and more restrictive as the dirt builds up but it's time to replace the filter then anyway. I can also buy the K&N thing if the engine has headers and additional flow mods that would allow a greater volumn of air to exit the engine therefore making the stock filter too restrictive. I have never seen anybody do a before and after dyno test for these high flow filters to prove they work. I would think that a vacuum gauge installed after the filter and before the throttle body would show higher vacuum with the stock (clean) filter and less vacuum with the higher flow K&N? I'll bet there's not a measurable difference?

 

Well, I look at it this way PC. The difference is comparable to trying to get a drink through one of those skinny little coffee straws versus through one of those big straws from McDonalds. You get a drink either way, and you can even get the same amount through either one. But with the skinny straw you have to work a lot harder at it.

The work your engine does sucking in air/fuel mixture is wasted power. If you make it easier for it to suck it in, you're losing less power, and therefore have more of it available at the wheels. Read my latest post in the ongoing thread about trying to get more out of my 4G93 for more details, but let me say that adding one of these filters to mine has made a tremendous difference.

BTW, the intake side is usually the one to address first. It is much more efficient and wastes much less energy to conmpress the exhaust gasses OUT of your engine than it does to suck the air/fuel mixtue IN. If you don't believe it, put your hand over your mouth. Try to suck air in, then try to blow it out. Pretty easy to restrict the intake, but a lot harder to restrict the output, eh? The same applies to your engine.

I could go into the physics behind it, but it would be more typing than it would be worth. I think my two examples illustrate the point well enough without all that boring stuff.

Lastly, everything I've seen shows that the K&N style filters don't suck in more dirt. The oil is the secret - it attracts dirt. You're probably too young to remember the old oil-bath air breathers of the 50's & 60's, eh? Suffice it to say that they filtered the air at least as well -and probably better than - any paper filter ever designed. The K&N uses the same attractive property of oil to trap the particles in the filter.

 

I find the problem with the straw example is that, sure you can use a small enough straw to show a difference but go to a 1" straw and a 1 1/2" straw, you will only be able to suck the capacity and strength of your lungs and your lung capacity only needs say a 1/2" straw anyway. the extra is just overkill.
The other example about the hand over the mouth seems to have more to do with a vacuum being created against your hand so it self seals against your mouth thus making it harder to break the seal as opposed to having to force your hand against your mouth to maintain the same seal, there is no vacuum assist. Again you would need to know the maximum air flow through a stock paper filter as compared to the air flow being created (and needed) by the engine and then calculate, by experiment, the pressure drop through the filter.
Now for the dirt part. You can look at a test done on this sight, www.bobistheoilguy.com (look up filter test) in which an extra paper filter was placed between the installed filter, either K&N or Paper, and the throttle body. The results showed more dirt captured by the extra filter when the K&N was installed.

 

If you are spoiling for an argument PC, you're barking up the wrong tree. However, I will take a couple of minutes to address a few things you questioned. I've seen that website before and both read and participated in debates over some of his test methods. Not completely sold on this info - nor do I know what his biases or motives are. More importantly, his test shows that the K&N drop-in filter does indeed flow more air than the others. The problem with drawing conclusions about my recommendation based on his tests is that what I installed on my engine is not a drop-in filter replacement. It is a truncated-cone style filter with a 2-inch "open" nose - an opening that is closed by a secondary, reversed, cone filter element. Between the outer and inner cones it has a total surface area approximately TWICE that of the stock paper filter. Twice the area = half the restriction. Additionally, installing this filter gets rid of the stock airbox as well - which may be an even more significant reduction in the airflow restrictions. The amount of extra "dirt" that his swatches supposedly "prove" that the K&N lets in, is pretty insignificant compared to the other filters as far as I can see. It is pretty much a matter of differing degrees of discoloration. He says it's "dirt", but it looks more like smoke discoloration to me. Again, since the filter I'm using has twice the area of a stock filter, I'm not so sure that his data/conclusions are applicable anyway.

Your refutation of my straw example would be valid - IF the stock intake system of the engine were 100% adequate to supply all the air the engine needs to perform its best. It isn't. If it were, a more free-flowing intake would indeed be overkill (as you pointed out). But it isn't. A four-stroke 1.8 liter 4 cylinder engine (like mine) moves 900 cc's of air in and 900 cc's of exhaust gas out every revolution - because each piston does one intake and one exhaust stroke every 2 revolutions. At 3000 RPMs that is 2,700,000 cc's of air per minute that has to pass through a filter and a 75 mm diameter tube. Converting that to inches it is 170,816 cubic inches of air per minute passing through a 3" diameter tube, obstructed by a filter. To make it worse, the air is being sucked through the tube - rather than forced being through it under pressure. More about why that is such an important point in a moment.

Your refutation of the hand over the mouth example doesn't really apply either. If you apply the exact same hand pressure for both inhale and exhale - or better yet use a large-mouth glass or other container, so the suction against your lips isn't a factor. You will STILL not be able to suck in air, but you WILL be able to blow air out. This is because compression is a more efficient way to induce flow of a gas than suction. Here is a simplistic view of the physics of it. Vacuum is finite - it is the absence of something. Once you remove everything - that is as far as you can take it. Once everything is sucked out of a container you have a "perfect vacuum". Basically the principle is that no matter how much energy you put into the pump (or whatever) that is creating your vacuum, you can not achieve any more than a 100% vacuum. Releasing the vacuum releases stored energy - in the form of the inrushing gas. However, the amount of energy released is always going to be the same - no matter how much energy you put into it to try to get more than a perfect vacuum, the amount of stored energy is going to be the same. Where this applies to an engine is that no matter how hard it tries to suck in more air, it can only flow a certain amount. The more restriction you place on it the worse it gets and more energy/power is wasted trying to overcome that restriction.

Compression on the other hand is infinite - at least theoretically. A gas can be compressed to the point of becoming a liquid. It can even be compressed further until it becomes a solid - and even then the solid can be further compressed into an even denser solid. All it takes is more energy. Releasing the compression releases a proportional amount of energy. The more you put into it, and the more you compressed it, the more energy you will get back out of it. Compression is just a more efficient means of inducing flow than vacuum.

Here's another example for you. Why do you hook the input of a hydraulic pump to the reservior and the OUTPUT of the hydraulic pump to the input of a hydraulic motor? Why drive the hydraulic by pumping pressure into it? Why not hook it up to where the reservior feeds the input of the hydraulic motor, and the ouput of the motor feeds the input of the pump? Why not drive the motor with suction created by the pump instead of pressure from the pump? The answer is simple. Because to achieve the same amount of power through vacuum as you can through compression requires a lot more energy, and you are also limited to exactly how much power you can achieve by suction - the "perfect vacuum" principle explained above. By using pressure you can drive the motor with much greater efficiency and how much power you can achieve is limited only by how much pressure your system can develop/handle. Compression is simply more efficient than vacuum.

This is also the reason that in internal combustion engines, the intake valves are bigger than the exhaust valves - despite the fact that the hot, burned exhaust gasses have significantly more volume (due to heat expansion) than the air/fuel mixture that produced them. Because it is much easier to PUSH a larger volume of gas out of the cylinder - even through a smaller valve - than it is to PULL the smaller volume of gas into the cylinder - even through the bigger valve.

All of that aside, I can tell you that installing this cone filter made a big difference in my little Expo's engine performance, and I can give you some anecdotal numbers to back it up. After installing the cone filter it has quicker throttle response, revs up much faster, revs higher in every gear, has more power - at both low AND high RPMs, and accelerates better. It pulls stronger to redline and actually seems to be reaching a higher top speed in each gear. I have a hill near my house that is 3/4 mile long and has a 1/2 mile long center section that is a 6% grade. About 1/2 mile from the bottom of the hill is a stoplight - which serves nicely as a well-defined starting point for the test runs - making it pretty much the perfect place for testing performance improvements. Right after doing the filter install I did a few WOT runs up the hill to see if it made a difference. At the start of the steepest part of the hill I was in 4th gear and doing 75-78 mph - compared to 70-72 mph with the stock filter. I also topped the hill at 62 mph compared to 55 mph before installing the filter! A 7 mph improvement over the original stock filter.

I just got back from a 2-day, 500 mile road trip that took me into some of the more rural areas of eastern Washington state. I got a chance to REALLY try it out on some of those 2 lane highways in the middle of nowhere. In first gear it will run up to 30+ mph, in second it will run all the way up to 50+ mph, in third it will pull hard all the way up to 70+ mph, and in 4th it will do over 90! With the stock filter it started getting breathless and running out of steam at about 40 in 2nd, 60 in 3rd, and 75 in 4th. On this trip I was also topping 3000-5000 foot high mountain passes at 65-70 mph in 4th gear. The very same passes that I was climbing in 3rd year at 55-60 mph on my last trip 2 weeks ago.

So, what it all boils down to is, argue with me if you want. There is no doubt in my mind that this filter is responsible for a significant performance improvement in my Expo. YMMV!

 

First Bob i'm not "spoiling for an argument". I approach this as a discussion, and I would like proof that the K&N type filters are really needed by stock engines. Nothing yet has
shown me.
You could have saved a lot of writing in your explanation on vacuum verse compression by just saying the potential Delta P from compression is greater. I also am talking about stock air filters versus K&N type higher flow, not the entire intake and exhaust system. The calculations you did to try and prove your point are simple math calculations based on the volume of the cylinders and the rpm. This would assume 100% volumetric efficiency for an engine, I know that you know that is not possible. If it were there would be no need for flow modifications on racing engines. You also assume wide open throttle. That's an important consideration. The throttle is a flow control valve that restricts flow as required. So your points are all theoretical and assume no flow retrictions from intake through exahaust, filter included and WOT. So what does a stock engine require in flow through the filter and what does the stock paper filter provide? We would need a flow chart showing the differential pressure reduction for the paper filter and one for the K&N and then know the flow characteristics for a particular engine at a specific rpm and throttle opening. Now I have never said the K&N's don't flow more, I think they do, but at what rpm and throttle opening does a stock engine need the greater flow, if any? I went on the K&N web site and looked up the HP gain on my 03 Ford Ranger 3.0L using a K&N. The drop-in K&N filter replacement showed ZERO HP gain, but the cone type K&N listed 9.38 HP gain. Now lets look at what RPM that gain occured, 4848rpm, not very practicle since I rarely see that rpm. They also don't provide any flow charts so a buyer can see if the HP gain drops off after 4848 rpm, or what it is at say 3000 rpm.
On your point about the test on the filtering capacity of K&N type filters verse paper filters. You discount the test by inputing assumtions an engineer would not normally make without some backup. Yes the higher dirt level could be something other than airborne dirt and I know this was not a lab test. But the conditions (considering the cost of the test) were about as controllable as could be achieved, and I think valid as a consideration. A high number of tests would have to be done to show a truer picture. I also think that if K&Ns did filter, at least as good as paper filters, they would tout that on their web site, they don't. K&N also has the capacity to pay for lab tests to show the filtering capacity of their filters, they either don't, or don't want to, because they market higher flow filters and recharge oil, not filtering capacity, and I think they know that their filters don't clean as well. Cheers.

 

MY apologies if I misread the tone of your previous post PC. Sounded like a challenge to a debate.

While you would have obviously understood the term "potential Delta P", there was no way for me to know that, most other readers wouldn't, and of course our public discussion here isn't just for our benefit.

You are correct, I intentionally kept the math simple and assumed a max-airflow scenario to illustrate the point. I should have qualified my statement with AS MUCH AS AS 170816 cubic inches (98.9 cubic feet), because, as you pointed out, the airflow requirements aren't at max all of the time due to the metering of the throttle body, restriction of the exhaust, etc., and the volumetric efficiency never reaches 100%. Regardless of that, even at lower throttle openings and airflows, the restriction reduction still yields proportional benefits, and there is also the benefit of the reduced restriction of the filter reducing the lag between increased demand (increased throttle opening) and increased supply - your basic improved throttle response.

You are also correct in your statements about what kind of testing would be required to completely prove and fully measure the quantity of performance improvement. K&N either hasn't done that level of extensive testing for every engine that they make a filter for, or if they have they aren't publishing the results. Personally, I have neither the equipment nor the inclination to try to perform them myself. In that regard, I can only offer my anecdotal experience - which I described very thoroughly in that last (long) post.

As for discounting his results on the efficacy of filtration, I have to admit, that my comments may have been a little "flip". Regardless of the exact cause of the discoloration, the difference in degree of discoloration on his swatches was pretty minimal as far as I can see from the pictures. The last picture is the most telling IMO. With all 6 of them side by side, I myself can't seem to see nearly as much of a difference as he describes. Maybe you had to be there. I agree that he did a fair job of making the experiment as controlled as he could, but since they were all done at separate times, instead of side-by-side under the exact same conditions, that could account for some of the variation as well. Additionally, common sense says that when you soak a cloth (filter) with liquid (oil) and then suck large volumes of air through it the airstream is going to contain some molecules of the liquid. So the oiled filters have to be passing SOME molecules of oil and depositing it on the secondary filter. Common sense also tells me that this has to be contributing to the difference in discoloration as well. Heck the little bit of oil that the oiled filters deposited onto the secondary filter media may likely have caused IT to trap more particles than what the dry media did with the paper filter. In that case the secondary filter would be dirtier because the dry ones let more of the dirt pass through and into the engine. Even assuming that there were NO variations in the test conditions, and his assumptions and conclusions are all 100% correct, the difference in the quantity of particles passed appears to be so minor that I would STILL be willing to accept it as a trade-off for the driveability improvement I am experiencing with my Expo.

One seeming contradiction that I find interesting; on the first page, to prove his point that the flow difference between filters is not very significant he shows a table of pressure drop readings taken at 6500 RPM and WOT. The stock intake with NO filter he shows as creating a .184 psi drop in air pressure - versus the worst stock paper filter tested creating a pressure drop of .249 psi. A difference of "only" .065 psi. Interestingly enough, although on the first page he discounts the effect that this difference in the filter media has on airflow, he makes this comment on the second page
"After 3500 miles of filtration testing, I am done. 3,500 miles of horrible power is more than I can bear. The secondary filter really kills flow and power above 4500 rpm....."
So, my question is, if that difference between the worst filter and NO filter is so insignificant in terms of performance, why would adding a second filter (the test swatch made from Fram air filter material) result in such "horrible power"? Why is it that a second layer of the same filter material "really kills flow and power above 4500 RPM"? I contend that maybe the difference is more significant than he makes it out to be.

What it all boils down to is this; for less than 25 bucks and a couple of hours invested, I saw some significant improvement in the performance of my Expo. It has snappier throttle response, a little better low-end torque & HP, a much bigger improvement in hill-climbing at freeway speeds, and a 10-15 mph higher top speed in every gear. However, I don't have an extensive data set of numbers derived from a controlled scientific experiment to specifically quantify the exact performance gains. In bringing the test results from this other website into the discussion, I took it that you were attempting to either challenge my statements about the improvement, or say that I'm doing something to damage my engine. As I pointed out before, and you (sort of) seemed to acknowledge, his testing is of a drop-in filter, and what I put on my Expo is a filter and MAF adapter that replaces the entire airbox and filter assembly. Therefore his results testing apples don't really prove or disprove anything about my results using oranges. Especially since what I recommended in response to tyronetaylor1's original question was the MAF adapter and cone filter like mine - NOT the drop-in filter this other website is purporting to have tested. As for whether the oiled gauze filter does as good of a job and is therefore potentially harder on the engine, I also maintain that the difference is insignificant enough - if it indeed even exists - that I am willing to accept it for the driveability benefits I am seeing from using it. After all, tyronetaylor1 asked how he could improve his performance - not how he could get the absolute maximum lifespan out of the engine. Almost any performance mod is going to shorten engine life to some degree. I feel that this one gives the most bang-for-the-buck improvement while having the least negative impact as a tradeoff. That is why I suggested it.

 

Hey Bob, I do agree that the increase in dirt is hard to equate as to engine damage. And I do believe part of the dirt at least is charge oil as I have seen other posts asking, "What is this oily substance on my throttle body". I did notice the cone filters come with a custom intake which appears to improve laminar flow. I wonder if the increased HP is more from this than the high flow filter? One test might be to remove the stock filter and leave the stock intake and do some test runs (no restriction), next install the cone intake without the cone filter and do the same test runs. Maybe you would feel the same improvement with the addition of the intake? I suspect this is the case due to the K&N HP figures for my Ranger. The higher flow drop-in produced no increase in HP, if there was, K&N would surely publish it. The other possibility is they prefer you to purchase the higher value unit.

 

I'm sure the cone filter itself yeilds some benefit - both because the material is less restrictive AND because there is more filter area - roughly two to three times as much.

As I said before, eliminating the restrictions imposed by the stock airbox is surely a big factor in the overall improvement. Possibly/probably an even bigger factor than the change of filter media. I'd like to get a paper filter of the exact same size, shape and style and try it out - just to see what the difference is. Unfortunately, I don't think there is such a thing. At least I've never seen one....

That makes the oiled gauze pretty much the "only game in town" for achieving the stated goal CHEAPLY. Ya' gotta' admit, ANY improvement for under $25 is a worthwhile investment!