cat and air filter on FI cars

carl

carl

True Classic
This is the first FI X I have owned and I have to admit, the FI seems to function very nice (unlike the 124 spiders which I always removed and added IDFs).

Anyway, I'm sure this has been beaten to death, but would a K&N type filter on the end of the AFM and removal of the cat produce any power improvement? And I don't mean what the Butt dyno says, I mean real actual improvements for normal street driving.

The air filter swap would be easy but the bolt/nuts holding the cat on my exhaust have become one with the car and would be an ugly job.
 
peformance

removing the cat and installing a straight pipe would help immensely, but it might be a no-no with state laws there. the k&n would help also and it comes with a d.o.t. sticker that shows compliance.
the free flow of the intake filter will clean un the engine compartment and the lack of the cat will lend a little more HP, but you will get hooked on how loud the motor is.....:headbang:
down side is you will have to have MORE noise from back there
that's the dark side is of which papa tony alludes to and there is no return.
mikemo
 
I would suggest performing the air box mod the Kymco scooter guys do. Basically your X1/9 has a drop-in cylinder type filter inside a can (air box). We mount pod filters inside hollowed out stock air boxes, in place of the drop in/panel filters. The air box acts as its own "environment" with more stable atmospheric conditions, which for our small displacement 2 stroke scooter engines is a must, and since the X1/9 FI air box is already about 90% there in way of this mod, why not. This is what you need to do:


Discard the stock drop in filter and mount a pod filter (might need to make a flag out of PVC or something ). Then cut a 1.5 in hole in the bottom/ side furthest away from the engine. Use some scat tube or something as a ducting and route it to the driver side air scoop. You will have to modify the air scoop to be functional. You should end up with something like this:



If you really want to get ambitious buy some of the thin foil type insulation from lowes/home Depot and wrap the outer case of the air box with it. This will further reduce air temps inside the air box and in theory provide better gains. GL
 
I can't say that I agree. I am not a fan of the wholesale removing of emission control systems.

K&N has always been a poor filter in reality, thus its minor increase in power or at least noise as most also ditch the quieting effect of most intake systems/housings. The reduction in filtering quality is not worth changing to one. In my less than esteemed opinion anyway.

An old cat could easily be clogged and the older designs are restrictive. Changing to a modern catalytic converter with a honeycomb matrix versus the earlier pellet style could certainly help. Removing a clogged one is certainly necessary, hopefully with a newer higher quality one.

In general the real increases are to be found elsewhere. A less restrictive air metering system (which means changing the majority of the injection system) or all of the real pumping improvements of larger valves, cam and of course increasing compression are the things which will really make a difference.

Of course if you just want some more noise one can hack away :)
 
I am totally in favour of removing any HP robbing system in our stock 75hp cars. I went so far as not only removing every emissions system, but actually turbo'd it on top. Lol. Remove away my friend, you will find joy at the end of the journey. Cheers,


Sent from my iPhone using Tapatalk
 
The FI motor has 3 areas where emission regs resulted in measures that really strangled it, where Fiat moved away from the original design just for emissions sake.
You can change those things back to near the original design and unstrangle the engine.
(The air filter is not one of those areas.)
1) low Compression ratio
2) 4 into 1 exhaust manifold
3) emissions type camshaft
 
Since your car is fuel injected, you don't have all the smog stuff like my poor '79 does. If I had an FI x1/9, I would do the air box mod I posted, and buy a modern high flow cat. I live like 30 mins from Fabspeed Motorsports, so I would probably go there.
 
Since I already have a "project" X, I don't want to do anything crazy and the motor is not coming apart in the injected car. Anyone have a part number for a K&N style filter that clamps on to the end of the AFM or rubber snorkel?
 
K&N R-1380

carl said:
Since I already have a "project" X, I don't want to do anything crazy and the motor is not coming apart in the injected car. Anyone have a part number for a K&N style filter that clamps on to the end of the AFM or rubber snorkel?
Click to expand...

Hi carl,

I have this one sitting on the shelf. It was recommended to fit and it is a K&N R-1380. If you look closely you can see that the opening that clamps to the AFM is off center. I have not installed this, so I don't know why. I guess it will allow more clearance for the engine cover to close if the "short" side is oriented up. I did grab an AFM off the shelf to make sure it fits into the opening, it does.

FI%20air%20filter%202.jpg


I also have a Vick's intake kit that came with a conical K&N style filter that looks twice the size of the R-1380. I believe the Vick's kit uses an elbow to hang the filter 90 degrees down off the AFM instead of straight out the side.

I went to take a picture of the filter on my 85, but realized it is another type that is cylindrical.
FI%20air%20filter%201.jpg
 
I have done the K&N on the red X1/9 and it made no difference in feel. Getting rid of the cat is huge. I put a straight pipe on the blue X1/9 and gutted the red X1/9. 30 year old Cats block the exhaust flow.
 
I just attached the K&N air filter directly to the Air flow box, replaced the cat with a straight pipe, and welded in a cherry bomb muffler. It's loud. It feels like it goes faster. I love the noise, and so do the other roadster drivers.
:headbang:
 
c84a2bcfa846eb559abaeb0c0e8aeae0.jpg


Not the best photo, but it's all I have access to, being not home at the moment. The generally questionable PO of my '85 installed this, which appears to be a 90 degree elbow and faux-K&N cone. It was already mated with a long runner header (IAP?), slightly hacked vintage exhaust (sadly, installed with leaks I had to clean up), O2 delete (huh?) and of course no cat, so I don't have a control point to compare to....definitely more snap, crackle & pop than my '81 had. (Which, yes, implies I am not saying it has any appreciable greater power to match the greater noise)

d5c5ec35e2c3295d8f0d0a0259a43895.jpg



Chris G

Sent from my iPhone using Tapatalk
 
The following has entered my head as conventional wisdom in regards to these things, can't say its right, just what I've picked up hanging around here (way too much):eek:

K&N bad, stock system does not choke the intake as is, all you'll do is start sucking poorly filtered (dirty) air; bad and waste you money.

Cat delete; our cats are not restrictive, I removed mine (for other reasons) and didn't really notice any difference, sounds a little "better" worse for the environment, exhaust smells worse

I have another exhaust with cat and it's going on the car the next time I dig in there (soon).
 
Switching to a K&N or modifying the stock housing to accept a K&N will increase noise, intake heat and reduce filtering effectiveness.

http://www.nicoclub.com/archives/kn-vs-oem-filter.html

This article is long but goes into depth explaining the difference between a paper filter and a K&N filter. The takeaway is that the K&N filters poorly at first, then clogs up with not much benefit performance wise. But the marketing is great for the product so everyone thinks it works great.

Changing out the 4-1 manifold to a header would likely be the best cost-benefit change you could do. The CAT on these cars isn't particularly restrictive, and is important for both emissions and exhaust noise.
 
The K&N has the offset to clear the cover:

X19fuelPressure0002.jpg


using a larger K&N now, that also draws in from the end cap. I clean & re oil them

B62D46E0-98F0-4E55-B458-92D095639EA9_zpsdox8m434.jpg


The stock box draws air up from under the car, so when moving air temp should be OK. Stop & go traffic in a hot climate with all that heat radiating off the blacktop, not so much.

I used a race cat, better flow, no stinky exhaust.

5973FAC9-33DA-4663-A2EB-8DF5D386339B_zpsuvo97yj3.jpg
 
I'm telling you all, mod the stock air box with a K&n indide and wrap it with foil over fiberglass insulation. It'll drop intake temps, provide fresh cool air from out side the engine bay or radiant heat from under the car, and it'll give a slightly better sound. Not to mention the air box will act as a particle separator and help eliminate the short comings of the K&mn filter it's self (if your concerned they don't filter)
 
When I had my car on the dyno I did several pulls with the stock air box in place and a stock filter with probably 5K miles on it and several pulls with the intake pipe wide open and there was no measurable difference in torque or HP. This was on an engine with about 20-25% more power than stock. Of course back when I ran a K&N cone filter, as others have said, it did sound faster.
 
Everybody,
Interesting debate.

However, no one mentions the ECU. No matter what you do to modify the engine, intake or exhaust the ECU will attempt to bring everything back into it's programmed parameters. You might benefit from launch due to better intake and exhaust but you will not gain much (hp or torque) until the ECU is reprogrammed to take advantage of the changes.
I might be wrong but everything I did to my Mazda 3 didn't take affect until I added a piggyback ECU. Then things got interesting, 185 whp and 210 ft/lb torque.
V/r, Mike


Nebraska Mike
 
Actually the system will automatically adjust within the information it receives. If the AF meter is pegging out and can't measure the greater airflow, it won't be able to add more fuel because it doesn't know what is really going on.

The Miata uses a very similar system (L Jetronic was licensed by a Japanese company that supplied Mazda and Nissan as I recall), it has more electronics added to allow it to work with tighter emission controls which is likely why the M didn't respond until you added the piggyback which likely enriched the mixture significantly to give you very rich power.
 
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Kmead,
Interesting. I thought that system is told to stay within a certain perimeter and would adjust to stay within those predefined perimeters. I did not think the system would adjust to the new performance modifications and give you more than what it was programmed to. The AFM would be also a weak area, as you stated. It will open only as far as it is physically able to.
So, mod or don't mod???That is the question.
V/r, Mike


Nebraska Mike
 
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