Individual K&N filters on MFI

[Cornpanzer]

I would really like to take the air box off my 70S and replace it with a pair of K&N filters with rainsheilds. It has been suggested in the past that this may actually hamper performance. Can anyone state with any authority if this is so?
TIA,
Dave

[HalM]

Dave, Get in touch with Paul Thomas. He runs K&N/s / rainshields on his 3.5. He can probably shed some light on this for you.

[Cornpanzer]

Yeah, but with 3.5L would Paul even recognize 5hp +/-
Besides, remember we drove with him down to Daytona.........its questionable if he has ever opened that sucker up!

[RSwannabe]

Dave,

I cannot answer with authority, but I can offer some input. I have a 2.2S motor with K&N filters and a sport exhaust (I seem to recall you run a sport unit as well and like it). WOW, does it sound good! I did not fully realize the difference until I drove Randy Wells' car (2.7 RS spec w/ MFI) a couple of weeks ago. His car is a lot quieter. My car is still very civilized at lower rpm's (by this I mean quiet), but after about 4,500 rpm the intake starts to make a truly glorious howl. When I am running at 80+ mph (over 4,200 rpm as I have a "Z" 5th gear) it can become a bit wearing, but in no way unbearable. As much as I like the sound of the sport muffler, I does not hold a candle to the MFI with the K&N's at high RPM. You need to try it.

As for power, I have read that the open filters make you lose bottom end. I have also read that sport mufflers cause MFI cars to have a flat spot in the low-to-mid range rpm's. All I can say is that my car pulls very strong from 3000 rpm and does not have any flat spot that I can detect. Everyone who has driven it is supprised by how much torque it has (Randy included) and I have yet to drive a car with sharper throttle response (Randy's included). I love the combination. Highly recommended.

Brooke

[70SATMan]

Dave,

I have a 2.2S motor with K&N filters and a sport exhaust... As much as I like the sound of the sport muffler, I does not hold a candle to the MFI with the K&N's at high RPM. Yuo need to try it.

Hi Brooke,

You lost me. Are you saying the sport muffler alone does not compare with the filter/sport combo? Are you still running MFI on your 2.2S?

This sport muffler topic has always intrigued me. I've read a lot of "He said, she said" on it. Has anyone actually run back to back Dynos with the two combinations? I always assumed that with the radical duration of the S cams the reduced backpressure was inducing scavenging. I'm also curious on the effect on MFI running E cams since they are milder. I know Ts seem to get a boost in HP.

[RSwannabe]

Sorry if I was not clear. I have a factory 2.2S motor with MFI. I have K&N filter housings modified to fit MFI and a Dansk factory style sport muffler (2 in and 2 out in the center).

What I meant is the sound of the MFI with K&N's is both louder and more glorious than the snarl of the sport muffler alone. I am not saying it provides better performance, or that there is some kind of synergy with having both (other than the sound), only that it does not seem to hinder my performance. I have not done any dyno testing or comparisons.

As to the whole "sport mufflers causes flat spots on MFI cars", I don't know. I detect no flat spots in my car's power delivery. I have never seen a dyno chart showing such a flat spot, but I have seen a dyno chart in Bruce Anderson's book showing an MFI motor gaining power across the board with a sport muffler. Still, I respect the knowledge and experience of many of the members of this and other boards who feel sport mufflers and MFI are not good together. My own personal take is that if it is hurting my power delivery, the impact is small and far outweighed by the joy I take in both the look and the sound.

Brooke

[70SATMan]

Gottcha, thanks. That's what I thought you were saying.
I love the look and the sound of the sports and when I get my 70 running will probably run one.

[LeafGreen]

I’ve often thought about doing that (if for nothing else to increase the cool-look factor), but I’m afraid it would set me back six months in the tuning department, as I think it would alter the fuel curve on my stock engine. My recent experience with MFI, coupled with many years spent fiddling with carburetors, has suggested that a stock fuel system is set up to run with the original air filter restriction and exhaust system.

Turning the air cleaner lid up side down on the family sedan to get that BAAAA-OOOOO sound was cool, and it may even have raised the HP of that Chrysler 360 from 175 to 180 on the big end, but in the big picture of things it impaired the overall drivability of the car – which, by the way, was pointed out by mom who had to drive dad to BART on cold mornings. Since I have been driving my 72T every day, I’m starting to realize the significance of the missing MFI hot air stove that is supposed to be on the left heat exchanger.

I’m of the opinion that there is always room for improvement, but the many quick tricks out there address only a very narrow band in the overall performance of an engine…..soooo, be prepared to do some serious tuning to get the most out of the modification, while making the car drivable in a wide range of temperatures (easier said than done). I don’t want to wait until it’s 90 deg. in the afternoon during the month of June to drive my car.

If others have put the cool K&N filters on an MFI car, and had it run well, I too would like to hear the gory details…….

[Scott Clarke]

Michael-
My otherwise stock 2.2E came from the P.O.with an Abarth 4 outlet muffler. It sounded great, but it was LOUD. In addition, I didn't like the appearance of the four outlets. I decided to go back to a stock muffler. Before I made the switch I grabed a friend and headed to a cunk of road where I could acelerate from 25 mph to around 90mph over a set distance. After changing the muffler, with similar weather conditions and the same amount of gas in the tank, and the same friend, the car was 1.5 seconds quicker with the single outlet muffler. I didn't notice any flatspots with either muffler, but there is more bottom end with the stock one. So, I'm quite convinced that some backpressure is useful for mfi motors unless they are somehow tuned to work with less.

Brooke-
In the name of science, perhaps you could perform the same test with the airbox. I'll loan you mine if you no longer have yours. I'm certainly planning on watershields for my 2.5 short stroke rebuild. It would be great to know what, if any difference, the filters make.

-Scott

[RSwannabe]

I've been wanting to quantify these issues myself. A little time at a dyno with a stock airbox and a stock muffler would answer alot of questions. I've got a stock airbox, but not a stock muffler. I'm sure I could get my hands on one though. Would people be willing to pony up $20 each to subsidize the dyno time? I'd be happy to make a study of this subject and produce some substantive data.

Brooke