christaylor

So I had my buddy's portable dyno over here today, dynoing my dad's racecar ('85 GSL, 90k miles on stock 12A, 3" pipe, RB header, etc.). Car had a new K&N on it for all the other screwing around we did. Last run, put Purolator paper filter on it. I put this filter on when doing dyno work on my car in September-ish. It ran a full race weekend at TMS (basically a 2 mile chassis dyno with some twisty ****), a 6-hour enduro (which put 600+ race miles on the car), and an extended regional race with this very filter. The Purolator (which has turned a nice gray from dirt and dust) made .5HP more than the NEW K&N. On my car six months ago, a K&N was 2HP better than a BLACK Purolator, and the new Purolator was 4HP more than the New K&N.

So, yeah, K&N is awesome.



(If you think you're smart because you have a ratcheting screwdriver with a light on the end of it, please back away slowly from this thread.)

boog

That sucks, i have a k&n

NewRXr

Carberetors are sensitive to vacuum in reguards to the fuel mixture they end up dumping. So Even though the K&N is physically less restrictive to airflow your carb doesn't compensate for the lower vacuum level at the jets. By the way you're running lean.

Vernon

Rx-7Doctor

iTrader: (13)

Kn filters only start working well when they start to get dirty.

cdrad51

like my ex

Tech_Greek

You've got to take into account different runs with different temperatures...there's no SURE fire way of telling the HP gain from an air filter unless you do them on two different days with the same temp and weather (humidity, etc).

- Tech

Alak

iTrader: (9)

The air is so clean up here in Canada I dont need to use an air filter.

Rx7carl

Interesting Chris. However I wouldnt make final judgements just yet. There are variables that could account for this. If you have a K&N thats over oiled it could restrict airflow. Im not in any way doubting your results, just saying that they could be skewed. And just the tolerances of the dyno can skew the results. They arent that sensitive/ calibrated. What airbox are you using? Stock I guess from your avatar? Those thing flow like poop. Unlike a dyno, a flowbench is calibrated before each use (at lesat mine is) and is VERY sensitive to changes. I have some data I took a while back, Ill try to dig it up.

Tyrael6666

Hes right, a lot of times it is recommended that you only clean those filters once every 60,000+ miles (depends on condtions) because they work their best when they are dirty.

Kentetsu

LMAO!!!

christaylor

I kinda doubt it... A/F is spot-on, best of any of my FB's so far.

Well, this is the second car and the second K&N filter that has sucked. Unfortunately, I didn't have a new Purolator (which consequently is the cheapest paper filter I've ever found) so I can't attest to the 4HP gain vs. K&N.

BTW - this wasn't on some POS DynoJet or Mustang Dyno. It's a DynoDynamics, Australian made version, wide-band O2 and all the hot-****. When I say, "Run", I don't mean one. Every time we do something we make 2-3 runs in succession, since as anybody that's played with a rotary on a dyno knows, they put up better numbers as they get hotter. And, since this is the second time I've gotten the same results, I tend to believe what I see.

BTW #2 - the DD is probably the most repeatable dyno you'll ever find. Since the correction isn't done by Buder and a **** on the side of the machine, you'll end up with very close results over a long period of time. If I can, I'll put my street car on the dyno next time it's out here and see what it says. Hopefully Brian will see this thread and chime in with some of the specifics of the dyno... I know you'll be impressed, Carl, and probably wouldn't put your car on anything but one in the future.

RotaryRevn

I read on the gmc message boards that people who dynoed their trucks with the k&n filtercharger kit on the 99 and up sierra/yukons actually lost hp's over the stock set up.

1984special

I used to have a k&n cone on my Yota and while it made lots of cool noise, it doesn't filter for crap. When I hold it up to the light, I see lots and lots of holes....

I have since switched to foam on my DD yota.

Here is an interesting read on air-filters in general. It is quite the topic of debate the toyota forums...

Another one here as well.

HTH

Tech_Greek

Rotary Engines have nothing to do with the intake element being hotter in different tempatures.

Think about it...

- Tech