(2007 fit base model mt) My exhaust knowledge is a bit rusty. What is the cylindrical object after my cat in the exhaust flow on the right side of the vehicle? I want to get headers but the kit im looking at removes the cat so i figure i could just move it back, and possibly put it in place of whatever the hell that other component is.

Thanks

Jon

 

Whoa! And you want to put headers on because...

 

Resonator. If you leave it out no problems but it will be a bit louder. And headers on a GD work just fine the ECM is less nannish than on the GE.

 

First off there is nothing wronge with putting headers in my car a long with my stock cat and muffler; i mostly want it for improved efficiency anyway. and secondly i actually figured out it was my resonator before i read your post loudbang but thanks.

But yea about the volume i kinda would like it quite since im a guy who enjoys his music, and i don't want to have to crank it up louder to hear it, nor do i want to listen to loud humming noises while im driving. I get enough of that from my winter tires. And i'm weary to put in a more noise canceling muffler (if there even is such a thing) because i don't want to increase the resistance to flow any more.

 

Removing your cat on a GD? Only header I know that does that is the Weapon R one... That is a SIGNIFICANT change to how your engine breathes, just removing the cat would be, and realistically speaking to get the best of that you should look into a Hondata FlashPro to actually tune for the changes in VE.

I have the DC Sports header on my car now, with stock cat and the 60mm Skunk2 exhaust. It's loud if you get on it and does drone a bit at speed. Conversely a friend with an 07 with the same header and OE exhaust except a simple axle back is very quiet with only some growl at higher RPM.

I do have plans to put a version of the Weapon R Race header on my car, but have held off until I can get dyno time and a tuner to re map for that long tubed 4-2-1 and no restrictive OE cat!

 

Ok i didn't understand all of that so i will just clearly state my intentions. I do not want to remove my cat. And please friend take my advice, removing your cat and your muffler on say a 1.5l engine like mine will give you litterally like 5 extra horsepower maybe at the maximum. So with that in mind, think about how pathetically little a low restriction cat or muffler would do.

If you want i can give you some links that show people testing those things with dyno's on a honda civic.

And as for the whole tuning part of it. My car has such little valve overlap not to mention no boost pressure at all, plus headers are designed for specific types of engines and the one im looking at (weapon r racing headers) is very compatible with my engine. So for my low hp no boost pressure engine im sure it will be excelent.

I would be more concerned about the whole tuning of it all if it were a much heaftier engine especially if it had a turbo or a blower.

But please, it pains me to see guys spend big money and not understand what there getting. In regards to the low restriction cat, im not telling you to not spend those hundreds of dollars if you want to, but just realise the fact that you will not be getting much more performance out of it depending on your engine, and if you have something like a naturally aspirated small honda engine i would very much say don't spend the money on those things. headers would be the only thing worth it in my mind.

I can expand on anything if you want, and thanks for the conversation and insight. and i would like to know, what do you mean by axle back? See im in the heavy duty mechanics field myself so im a little lost in the small car world lol.

 

So, I read your post and got a bit hot headed... But I took a breath, as this is the internet, and tried to put together a comprehensive reply.

I have been around a while in the Fit community, if you search my posts and threads you will see that I am a huge proponent for the earlier GD chassis and it's L15a1 power plant and either have helped or am still currently working on bringing more parts back to market.

Now back on to topic. First off, here is an excellent article about the GD Fit you should take a look at The Truly Amazing Honda Fit/Jazz

Also, another thing you need to understand is JUST HOW MUCH, the factory ECU will limit the car. ANY bolt on performance parts on a 2007-2008 GD Fit, including the Weapon R Race header are more than likely to LOOSE POWER. This is due to just how "intelligent" the factory ECU and sensors are. After you've bolted up your new shiny parts, your butt dyno will feel the improvement then within a week of driving it, the ECU will pull fuel and timing to compensate for the increase in flow to attempt to achieve a more "economical" target Air Fuel Ratio for "better" "economy" and MPG This makes your new shiny parts only good for making more noise.

I and so many others, have documented this on a dyno. Before re tuning via FlashPro, when my car with a matched Intake, Header and Exhaust system, barely recorded 89 HP at the wheels. After simple fuel modifications overriding the OE ECU, that jumped to 99.9 HP at the wheels.

So, when you say you are sad to see people spend $$$$ on performance parts with little to no gain, you are completely correct! You are also correct that a quality, 4-2-1, high flowing and long primary exhaust manifold will give you the BIGGEST gains from a low displacement NA engine. However, ALL of those gains will be LOST if the factory ECU is allowed to "re learn" the changes you have made to static Volumetric Efficiency.

THE FIRST modification you should purchase if you are interested in more "efficiency" or power/torque/MPG whatever, is a Hondata FlashPro. Period.

NO I don't work for them and am no Shil. I am not sponsored or encouraged in any way by Hondata. I had to hound them, along with countless others to even get them to make the FlashPro, and as it's earliest adopter ( My unit's serial number is "0000") I am continually doing my best to share the benefits with the community.

Another bit of data that might help (you will need to open this in an Internet Explorer window for it to work.) Here is some detailed info on the OEM Cam in a Fit. you might be surprised: CATCAMS racing parts [camshafts-valve springs-retainers-connecting rods]

As far as the CAT/Muffler. IN a car that makes barely 100hp, 5 more is a 5% gain. So that cannot be discounted as a "minor" gain. Also, the OE CAT itself IS restrictive on the Fit. This has been proven on dyno's as well. I believe it has to do with the "oblique" angled entry they used to get more exhaust gas to contact the catalytic core:


Now, I regularly compete with my car in SCCA Solo events. We have strict rules that limit what types of modifications we can and cannot do on our cars. The biggest areas we can effect to make more power, are that we can change anything after the exhaust ports in the head. The only limitations are that we must retain a high flow cat mounted in the system within 6" of where the OE cat's exit was and that it has to exit the vehicle past the driver. I have a Weapon R Race header, but as I am not allowed to run cat less in my class I intend to install a "high flow metal core cat" in the second section of the header, replacing area after the 2-1 collector and potentially the flex joint.

It should look something like this:


Again, I plan to run a cat, and insert it here:


Since this cat is rated at something like 500+CFM, I am not worried about it reducing flow:



I hope that help's explain where I was coming from, where I am planning to go and why

 

Nice. Well first off there's nothing to be mad about. When you said tuning i thought you were talking about modifying the exhaust or something not the ecu. I was under the impression that the parts i was looking at would not degrade performance. because im aware of the fact that certain parts can be too much but i wouldn't think that it would cause the problems you say it will.

Now im not sure if i should do anything to my exhaust or intake if i have to reset the ecu on a dyno.

and the 5 horsepower i was talking about was if you removed the muffler and the cat. But thats not really an accurate thing to say i guess because without headers you wouldn't have good scavanging. But with headers, taking off your cat and muffler might increase your hp by 1 or 2.

so what is that flash pro you were talking about. Im assuming that allows you to change your injection timing and amount of fuel put in and such?

So i think if i get these parts and have to take it to a dyno and reset my ecu with flashpro. I wonder how much all that would cost me.

And as for the weapon r racing headers, i was actually thinking of putting my cat in place of my resonator. How much does it matter were you have your cat? is that going to cause problems having it further downstream?
I might do what you are planning on doing.

But yea i wouldn't even know were to begin in regards to what you actually set your ecu to. Im not sure if i can do these then lol.

like i say, im not really a profesional in the world of newer cars and really in the world of cars period since i work in the heavy duty and semi truck fields lol. We work with diesels, turbos and injectors and all that a hell of a lot but we don't do any tuning of ecu's or anything.

 

I think it was more just me being in a general bad mood, hence why I took a break from the internet before replying

I'm no whiz when it comes to tuning. My experience with "moding" things was mostly 2-stroke things on two wheels, and things with manual choke carburetors before the Fit!

New EFI (Electronic Fuel Injection) tuning is mostly Black Magic to me. The god ole Clark's law "any sufficiently advanced science is indistinguishable from magic."

Tuning these modern computer controlled cars is both a huge amount of science AND an art form as far as I am concerned.

The Hondata Flash Pro unit you can read up about here: FlashPro Fit

They are NOT cheap. But, there is a "group buy" currently going on where the vendor takes a bulk order and sells them for 10+% off the list price: https://www.fitfreak.net/forums/aj-r...group-buy.html

Not sure how low A&J Racing has gotten the price, but that group buy only needs 2 more deposits to complete the discounted purchases.

A "Race" header like the Weapon R one will require Dyno time to really be properly tuned. Most shops are $100 or so an hour, with additional charges for things like a wide band Air Fuel Ratio gauge and or technician time. Even then, a competent tuner shouldn't need more than 1-2 hours with the Fit to at least get to a stable and safe tune. More than that will probably be into the area of diminishing returns.

Since the FlashPro can take detailed logs of your engines behavior by the built in sensors via the OBDII port, there is also the option to go with an "e tuner." These guys take the detailed logs from you and your car, then adjust the fuel/ign maps and other parameters and Email it back for you to try out.

I had my initial tune done on a dyno. Since then I have been working with a user on here, DiamondStarMonsters Unofficial Honda FIT Forums - View Profile: DiamondStarMonsters, who offers E tuning services and I have been VERY happy with the results. He has great turn around times and has a vast knowledge base on the subject. Very reasonable rates too

Even then, for a SIGNIFICANT change like a 4-2-1 high flow header, I plan to get the car on a dyno for an initial dial in before going back to E Tunes to revise and refine


Oh, and as far as having your cat as far down stream as where your resonator is.... At that point it really wont be very effective... Honestly, If I didn't HAVE to run one for class rules compliance, I would not. It's a damn shame to have to cut up the beautiful welds on the Wapon R product to effectively add a restrictive element, no matter how slight! D:<

 

Well actually the only reason i want to even keep the cat is to obey the law. I don't care if its less effective. but anyway now im thinking maybe i wont do anything to my exhaust however. I am now just wondering if it would benifit my engine to go with a better flowing intake system without any tuning of the ecu. the weapon r secret weapon intake system. Would that even do any good efficiency wise? I would think so cus i know that when guys go to the race track with just there comuter car they take the air cleaner off and get way more performance.

I obviously realise theres a lot less restriction that way but im talking about considering the effects it may have on the computer changing things and screwing it all up because of much greater air flow. i would think that there might be a problem bceause of the injectors being set the way they are. the injectors might not be able to keep up with that greater amount of airflow that it wasn't designed to use so to speak. But i was assuming that because its all electronically controlled that it would just close the throttle plate more to not let too much air in.

Do you think just put in the secret weapon intake system with not tuning is a good idea to improve engine efficiency?

 

Nope.

Anything that you bolt on in an attempt to find more efficiency, the ECU will attempt to reset to it's pre defined AFR goals.

You COULD do what I used to. Disconnect the battery cable and have the ECU return to "learn" mode any time you wanted to have more power. Before FlashPro I used to do that at events when competition was tight

But, soon as the ECU has reset all its monitors and gone through a few closed/open loop cycles you will be back to or below where you started.

 

Yes but what you said there makes it sound ok to me. Its going to obviously try to maintain the proper a/f ratio which it will. But getting a lower restriction air cleaner would reduce and probly eliminate moments were the engine needed more air and couldn't get it. See the ecu wont let me go to lean so we don't have a problem there, however it will never be lacking air when it needs it. Doesn't that sound right? It makes sence according to my limited amount of knoledge on this engine.