Myth Busted on HD "Stage I" "High Flow" air cleaner

[DK Custom Products]

There is a persistent myth perpetuated on the internet, at some dealerships, and who knows where else....

Myth: the Stock Air Cleaners on the 103 Twin Cams, like found on the Rushmore Models, is a Stage I High Flow Air Cleaner.


While the new stock air cleaners (2014-Up) are less restrictive than previous years stock air cleaners, they are still very restrictive.


We knew this from seat of the pants experience. But "Internet Truth" being so widely accepted, we decided to put it to the test....on a Dyno...and publish the results.


Here they are:

2014 Rushmore High-Output Twin Cam 103 with the stock "High Flow" air cleaner vs. a DK Outlaw Real High Flow Air Cleaner.




A 9.5% Increase in power when you twist the throttle pretty much says it All.



Over 9 ft lbs increase in Torque and a 6 Horsepower gain by replacing the "High-Flow" Stock Air Cleaner with an Outlaw High Flow Air Cleaner System.



Many folks are happy if they get that much gain out of a set of cams!

DK Custom High-Flow Air Cleaner Systems
Street Developed
Street Tested
& Dyno Proven

Kevin

[FuzzyWuzHe]

Nice info ... great when you can play all day on a dyno ...

[Peter A.]

Great info......may have missed anything on this
but would you get anything near the same result
Or better,
with the earlier 103 (I.E. 2010)?

[DK Custom Products]

Nice info ... great when you can play all day on a dyno ...

Yes, it is. It was a long day, but fun!

Great info......may have missed anything on this
but would you get anything near the same result
Or better,
with the earlier 103 (I.E. 2010)?

On the pre-2014's the improvement in moving from the stock air cleaner to one of ours is even more significant. Primarily because on the '13 and earlier models the stock A/C was more restrictive.

Here is a 2011 chart to give an idea-



Kevin

[NHBAGGER]

Were these results from strictly bolting it on, no retuning?

[HDB0B]

I happen to really like the look of my stock 2014 air cleaner. How about you throw a K&N replacement filter into the mix? A $60 K&N versus a $20 stock element is something I might purchase from you as a less expensive option for a bit more performance and allow me to keep the stock look.

Thanks!

Bob

[GARYD]

I'm interested. Is that with stock exhaust? I usually don't do any engine modifications, I prefer stock (less headaches later). If I do anything, I'll do the A/C, slip-ons and maybe a tuner, but hate spending money. I don't like messing with what the factory deems correct. I guess freer flowing is a better thing.

Last week I asked the parts guy at my dealer if just adding the Stage 1 A/C would do anything for me(they had it on sale) and he told me it wouldn't help me at all unless I also did the mufflers.

What's the $$$ of your kit?

[MB1953]

I happen to really like the look of my stock 2014 air cleaner. How about you throw a K&N replacement filter into the mix? A $60 K&N versus a $20 stock element is something I might purchase from you as a less expensive option for a bit more performance and allow me to keep the stock look.

Thanks!

Bob

I would agree with Bob... I like the stock AC can on my '14, and have already added a K&N element and your discrete breather kit. Bike definitely seems to run better, but I have no way of quantifying it. Getting ready to bolt on the remote filter and cooler kit, and looking at a tuner, but it would be nice to know where I am now, besides continually emptying my checkbook.

thanks and keep 'em coming!

[DK Custom Products]

Were these results from strictly bolting it on, no retuning?

If you are asking about the first Dyno Chart, that was with a canned Stage I tune for the stock Air Cleaner and a canned Stage I tune for the DK Outlaw Air Cleaner. Apples to Apples comparison.

If you're asking about the 2nd Dyno Chart (on the 2011 Tri-Glide) that was with the stock air cleaner and a canned Stage I tune compared to the Outlaw Air Cleaner with an autotune on top of a canned Stage I tune.

I happen to really like the look of my stock 2014 air cleaner. How about you throw a K&N replacement filter into the mix? A $60 K&N versus a $20 stock element is something I might purchase from you as a less expensive option for a bit more performance and allow me to keep the stock look.

Thanks!

Bob

If you just do the filter, it will be a bit better than stock, but not much. But, if you replace the filter, remove the plastic backplate & get an external breather system on it, then you'll get a bit better than halfway. We did that. Just have not done an overlay of the charts yet. But it will go from 96 & 78 to 100 & 82...so not as good as 105 & 84, but a nice bump.

There are more factors in performance than just a free flowing filter...a very big thing is How the air flows After it gets past the filter & before it gets into the throttle body.

We can get you the K&N filter (just call or email the shop) and you can cut the plastic away yourself, we also have External Breather Systems that will fit. (call or email the shop).

We recognize that a lot of folks like the look of the stock cover, so we have been working on a design of a system that allows the continued use of the stock cover, but has all the benefits of a True Stage I Air Cleaner. It should be on the website within 3-5 weeks.

That is one of the things we were doing a lot of testing on the Dyno for back at the first part of the month. We are in production of them right now. Tentatively they will be called the Outlaw 606.

I'm interested. Is that with stock exhaust? I usually don't do any engine modifications, I prefer stock (less headaches later). If I do anything, I'll do the A/C, slip-ons and maybe a tuner, but hate spending money. I don't like messing with what the factory deems correct. I guess freer flowing is a better thing.

Last week I asked the parts guy at my dealer if just adding the Stage 1 A/C would do anything for me(they had it on sale) and he told me it wouldn't help me at all unless I also did the mufflers.

What's the $$$ of your kit?

Yes, all the runs had free flowing slip-ons installed. While you will not get as much out of an air cleaner upgrade if you are running the stock exhaust, you will definitely get a bump, significant enough that you will feel it....probably close to 50% of what the charts show. I'm sure your parts guy was well meaning, but what he told you is inaccurate.

We have Stage I Kits ranging from $240 and up. The one on the 2014 Dyno chart is $609

I would agree with Bob... I like the stock AC can on my '14, and have already added a K&N element and your discrete breather kit. Bike definitely seems to run better, but I have no way of quantifying it. Getting ready to bolt on the remote filter and cooler kit, and looking at a tuner, but it would be nice to know where I am now, besides continually emptying my checkbook.

thanks and keep 'em coming!

You have done (and are doing) some really good stuff. If you will cut away most of the plastic backplate on your A/C, you will get an even better bump.

A tuner will give you another nice increase, but they can cost some $.

Look at the FP3 if you're a Smartphone owner, or for just a little more, and the tuner I think is the best (we run it on all of our bikes), then look at the Power Vision.

An inexpensive way to get the AFR out of the lean/dangerous area, and allow you to run a free flowing air cleaner and exhaust is the FL-ViED-10. Not nearly as beneficial as a Tuner, but definitely an inexpensive and safe way to go.


Don't know what slip-ons you are running, but there is probably room for even more power at a very low cost....like a meal at McDonalds type cost....but that is only after you get some sort of tuner.

Kevin

[DK Custom Products]

Getting back to the original post of this thread....the idea that the stock air cleaner on the 14+ Models is a "Stage I" High Flow air cleaner.

We have heard, over & over, "with the 2014+ Rushmore's the stock air cleaner is all you need for a Stage I upgrade. You won't get any extra power out of it by going to an aftermarket Stage I High Flow air cleaner, or if you do, it will be so small you will not be able to tell when riding."

We've even seen some dyno charts showing just a tiny increase when going from the stock air cleaner to an aftermarket!

But what perplexed us was what we experienced in the seat of the pants. When we go from the stock to an aftermarket A/C was a very obvious increase in power, or so it seemed from our butt dyno.

Plus, just looking at that tiny paper filter in the stock "High Flow" air cleaner...it just did not make sense that was not restricting the flow.

As we know, seat of the pants can play tricks on us sometimes. This is why a couple of times a year we rent a dyno for the day. We usually have 2-4 bikes, and 10-20 parts with us.

The purpose being to test the parts on a variety of bikes to determine if they are any good, or if we need to go back to the drawing board, or just abandon the idea.

Last month, one of the things we were most curious about was testing the stock air cleaner on a 2014 103 Tri-Glide and then swapping out the air cleaner to see what, if any, change there was.



Finally the day arrived! On the 2nd of last month we had a dyno for the entire day.

It was a Long day! We spent over 11 hours testing 31 configurations over 4 different bikes.

We are fortunate. We are able to pull the bike up on the dyno and leave it there as we change out parts, testing each one. Then we move on to the next bike and do it all over again.


When we do the dyno pulls, the first thing we do it get the bike to 210 degrees, as measured by the IR gun on the rear cylinder head. We then turn on the fans and do at least 3 pulls with each configuration, to make sure we are not getting an anomalous run/data.

The reason we get the temp the same each time is so that the comparisons between different configurations is as close as possible. We cannot control the ambient temp or humidity, but the weather station built into the Dynojet dynamometer automatically adjusts for those factors.


Here are a few pics & videos-























We also had a Street Glide, but I completely forgot to get any pics or vids of it.



Click HERE & HERE to see videos of the 48


Click HERE for a video of the DK Sporty


Click HERE for a video of the TG



SO, getting back to the Stock "High Flow" air cleaner.

We did this test on my 2014 Tri-Glide.

We started with the stock "Stage I" air cleaner, free flowing slip-ons, and the canned HD Stage I tune. A complete Stage I upgrade (according to HD & others).

We then changed to a DK Outlaw A/C, which is a True Free Flowing Air Cleaner, and we used a canned Stage I tune for it. The exhaust was not touched.

The results were about what we expected. However, it was very nice to know that, in this instance, our butt dyno was accurate.

We have kept quiet for a long time, even though we believed that the Stock air cleaner does not flow enough air for a good Stage I upgrade, we did not have proof. Now we do.

The stock A/C is NOT a true Stage I A/C and will bottleneck power gains one would hope to see when adding free flowing slip-ons and a tune.

This weekend, or next week I'll have a few more dyno charts posted up, both on this subject and other bikes and parts we tested.


Kevin

[scooterbum46]

Kevin - one of the issues I've wondered about is the practice of trimming the back plate or otherwise getting rid of it (like some of the A/C kits that use a new back plate, but the stock shell). This seems to pull more air from between the jugs, with a much higher IAT than if all the air were coming from the front or outer side where the air is cooler. Old hot rodder brain sez "get as much COOL air as possible"... My PV shows IAT at a significant increase in temp over ambient and I'm running an A/C that uses an open back plate (FM kit) Your thoughts?

[DK Custom Products]

Kevin - one of the issues I've wondered about is the practice of trimming the back plate or otherwise getting rid of it (like some of the A/C kits that use a new back plate, but the stock shell). This seems to pull more air from between the jugs, with a much higher IAT than if all the air were coming from the front or outer side where the air is cooler. Old hot rodder brain sez "get as much COOL air as possible"... My PV shows IAT at a significant increase in temp over ambient and I'm running an A/C that uses an open back plate (FM kit) Your thoughts?

I know exactly what you mean, having had exactly the same thoughts myself. Give you an example. We have many variations of the 587 air cleaner.

I ran this one for a long time-



Which as you can see has a solid backplate and then air is drawn freely from all around the filter.

Then we we got ready to go on the Alaska trip I wanted to run a bobber cover, so that all the calcium chloride on the roads up north would not have a straight shot at the filter element to cake it up.

It looks like this-




As you can see it makes the air come into the filter element from around back of the cover, close to the hot engine.

My brain also says, cool air....as cool as possible. We know for a fact that the cooler the air, the more oxygen it has per cubic foot, which means more power.

Counter-intuitively, there was no measurable difference in the IAT (Intake Air Temperature) between the two set-ups pictured above.

To further confirm this, we've done dyno pulls, back to back, with the above two set ups, and there was no difference in horsepower or torque.

btw, the IAT is measured right about dead center of the throttle body, about halfway between the air cleaner and the intake ports on the cylinders. So the IAT reading we see is quite a bit warmer than the air actually entering the throat of the throttle body.

Notice how the IAT drops significantly when you roll on the throttle. This is because much more air is moving thru the throttle body, and it is not having time to be heated up by the metal surrounding it (the throttle body).

All that said, just like you, I always want to give the best chance to get the coolest air possible passing thru the filter element. It certainly can't hurt.

For that reason, if I was opening up the plastic stock backplate, I would do it be drilling holes along the sides of it, not the back of it.

On a related matter on the same subject.

I was concerned that using the Wards fans or the Love Juggs fans, which blow air from the left side of the engine across the heads and cylinders...that this air that is getting heated up would be going directly into the air cleaner.

Again, both on the road and in dyno pulls, there was no measurable difference with the fans on or off.

There really is a tremendous amount of air being pulled thru the filter element, and when running down the road there is so much fresh, ambient air going past the air cleaner that the vast majority that is being pulled in is coming from that source before it has a chance to be heated up by the cylinders.


Kevin

[scooterbum46]

Great answer, thanks! I had wondered if the TB was getting heated by proximity to the cylinders... I'll watch IAT on some long roll-ons..

[DK Custom Products]

I've had some questions about the Outlaw air cleaners that we make, someone even referred to them as "magic".

First, here are some quotes from a couple of Customers-

"If people only knew what a difference it (636v) makes above and beyond other high flow systems you would have the market cornered." - Dennis T

"Just put one on my Slim. Took off a SE extreme ventillator and bolted on DK's 636. My seat of the pants dyno says the bike picked up power, the throttle is more responsive, you can hear the filter sucking air at idle (sounds cool), and it may be my imagination but the exhaust seems to have a deeper tone when I nail it." -Mitch


Here is a Dyno Chart from one of our Customers running one of our Outlaw A/C's-




Here's another chart from a Sporty that we ran about a month ago. While it is not a Twin Cam, like found in the Tri-Glide or Freewheeler, it still give an idea of the drastic improvement that can be had with a proper High Flow Air Cleaner-




Our Air cleaners are obviously not magic, BUT, Not all air cleaners are the same.

Many times I hear something along these lines, "all high flow air cleaners perform about the same, just choose one that you like the looks of".

The "new normal" is an air cleaner that feeds hot, oily, oxygen depleted air into the air cleaner, bypassing the filter element. Also, most "new normal" air cleaners have flow disturbing stand-offs inside the cavity (on the throttle body side of the filter element). Then there is the shape of the filter element, and more. These A/C's are all very close in performance.

There are only three companies, that I know of, that are still making true performance air cleaners that can be bolted right onto a Harley. Hammer, NRHS & DK Custom.



There is no one big thing that makes an Air Cleaner better than the "new normal", it is a synergy of quite a few smaller things.



Almost every aftermarket A/C has a filter element that will flow more CFM of air than a Twin Cam can eat...so what makes one different from an other in actual, on the street performance (or on the dyno)?

Besides making sure only clean, dry, oxygen rich air gets into A/C cavity, the thing that makes the biggest difference is, HOW does the air flow AFTER it passes thru the filter element.

Our air cleaners are not the "blingyest" looking (we are working on that), but we have put a tremendous amount of work in how the air flows once it is past the filter element...and that difference is felt when riding, and shows up on the Dyno charts.

Kevin

[DK Custom Products]

More information on Outlaw HiFlow Air Cleaners, and a bunch of Dyno Charts can be seen HERE.


Kevin