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89 CRX si
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Discussion Starter #1
I currently have a DC Sports header and a DNA 2 1/4 inch cat back exhaust. I live in a area that doesn't require vehicle emission inspections and I was thinking of replacing my 29 year old factory cat with a matching DNA test pipe. Are there gains to be had or will be as well off with the factory cat?
 

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Ditch the factory old cat and spring for a 3rd party OEM replacement.

Unless you increase the compression quite a bit and run a much hotter bump stick, the difference between oem cat and freeflow pipe (test pipe) is nearly un-noticable on a dyno.

The exhaust noise will get a bit more annoying though, hence the recommendation of finding a replacement cat, or a 3rd party high flow cat.


BUT, it dpends on vehicles and engine types.

My 2013 Honda fit with its L15A7 actually saw very noticeable gains with a dual cat delete, only because the factory cats were very restrictive. I got noticeable improvements at the dragstrip (over 0.1 seconds shaved), I got better fuel mileage, and the car was much better responding to the throttle.


Both my 97 civic auto DX and my manual 95 accord LX saw little or no performance differences. Ive put nearly 40k miles on the civic while owning it, and around 6k miles on the accord, which only recently got its old cat AND 4-1 tiny manifold replaced.

4-1 header on the accord made a nice imporovement, but nothing to write home about.

Civic saw a very slight gain from a 99 d16y8 exhaust header to an ebay chingo header, only due to the collector being over half an inch bigger in effective inner diameter
 

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Brokedick Millionaire
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D15Beast7, Stock cat, Cherry Bomb muffler, straight pipe, no different between them. MOstly due to the OEM flange choke point
 

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89 EF 4wd sedan
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My 2013 Honda fit with its L15A7 actually saw very noticeable gains with a dual cat delete, only because the factory cats were very restrictive. I got noticeable improvements at the dragstrip (over 0.1 seconds shaved), I got better fuel mileage, and the car was much better responding to the throttle.
What time did you run out of interest?
 

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with a gutted rear interior, no tools, no spare, passenger seats and rear "magic" seats removed, and all door panels removed, I ran a best of 16.0 at I think 85mph, maybe 87mph. DIY intake with velocity stack (BLOX 6>2.5 stack, BLOX 6" filter), weapon R (garbage, broke a few thousand miles later at EGR pipe) dual cat delete, "custom" 2" straight pipe exhaust with a thrush turbo muffler from autozone, 2" suspension drop with Dropzone GD chassis-based springs, and a taped up front grill and taped wiper cowl. A forgotten, but big change in performance, was from setting valve lash to honda OEM spec. Even on the car with under 10k miles, all exhaust valves were very tight, and several of the intake valves were loose. Gained 3-4mpg after this as well.

Full interior with a subwoofer box and amp, and a second battery (aka, showed up to track too late to gut), I ran a 16.3 or thereabouts. Approz extra 400 pounds, it was 5 subwoofers at time, triple 10s and dual 12s. One big ass amp and the second battery was a group 34

During this time I was approx 190 pounds, full military sexiness at the time lol.

I was pretty proud.

The hodna Fit needs about 2 full tanks of 93 octane gas to adjust timing. (this was monitored with a scanner adapter and torque pro on android)

My very first drag run with full interior, but clean of tools and audio, was somewhere in teh neighborhood of 17.2 with several tanks of eth-free 87 octane. HORRIFIC factory tires, was able to roast them throughout 2nd gear, whcih hit barely 55mph at I think 6600 rpms. I either was forced to baby the launch and bog bad, or hit the green light at 4k rpm and spin threw 1st, and sometimes almost stalled going into 2nd. Stock airbox is VERY suffocating. 1.25" cat throat on primary was painful to find out, and second cat was on a curve, restricting good flow even more. Stock muffler had a heatspot that was blue and purple before the car ticked over 5k miles, car drove better with it unbolted while experimenting.


At a later time, I had my 1992 camry 2.2 auto, full interior, and ran it stock with a full ignition tuneup versus it with a modified MR2 header, resonator and cat delete, and a cheap ebay intake. I forget the actual times, but I believe I was around 0.1 seconds different.

I lvoed the Fit. The foolishly short gearing, and a good tire like the Ohtsu FP200?? (Falken ZE512 rebrand), you can get VERY predictable and consistent quarter times.

I think one night I ran 7-8 runs in a row right after one another, all within 0.1 seconds of each other.

Car was already hot and heatsoaked everynight, the dragstrip was about a 30minute drive from Fort Hood (Little River dragway)

EDIT, added some info.


If I find a good condition 09-11 Fit manual, Im buying it. They are lighter than my 2013 by about 80 pounds since they have a lot of equipment that was optional, rather than standard on my 2013. I do not understand where the 80 pound number comes from, but a member of fitfreak (fit forum) had a base model manual 2010 adn a base model 2013, one each for him and his wife, and apparanetly worked somewhere they had a scale capable of weighing a car. 09-11, keyless entry was not standard, and some suspension components were different. Even a spare tire was an option in first year or 2 of the Fit GE gen
 

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One of the guys on fitfreak raced his jazz in japan, and was as far as I can remember, very successful.

Over there, the jazz/fit gets the RS trim, with a 6speed manual.

That, and japanese models are a couple hundred pounds lighter, and get more power since they dont use a buttload of emissions.



I reckon a USA Fit gutted out, simple chassis bracing, and a tune from the hondata flashpro would be quite easy to be deep in teh 15s, and be a very fun car to drive/race.

I had a lot of fun with my Fit, but it REQUIRED a rear swaybar bolted up and stiffer springs.

in stock form, passing a semi truck was white knuckle inducing
 

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Brokedick Millionaire
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Gird.Life Spec Fit.

Also look into two fits that ran in PWC/Conti with Tom O'Gorman at the wheel. KlapTrap now has a K24 power :)
 

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Tape-R taper/driver
EC3, ED8, ED9, EE5
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Hondas without cats tend to sound like hot garbage.

I did a back-to-back-to-back test on my 01 Prelude SH with the OE cat, no cat, and high flow cat and the difference between all 3 was less than 1.5hp peak and not enough "under the curve" to matter, but the sound between the catted pulls and no cat was night and day.
 

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catless and muffler-less GE Fit sounds like a stroked out CBR and twice as loud.

I think its part of the large stroke and tiny bore. I liked it. Military Police did not. At least they slapped my wrist instead of writing a ticket lol

catless and mufflerless civic/accord/prelude/crv/ etc... D/B/H/F sounds like straight doggy poo unless its cammed and compressed!!


Bone, you mention a K24 Fit.

Check out the V6 Fit build. no idea if its done, I just remember reading about it 3-4 years ago
 

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Asshole
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How big of fireballs you wanna shoot?

Carbed 86 Accord with a bad cat...HUGE fireballs under the car!
My first car was a carb'd 5 speed 4 door 86 with the A20, one of the first car forums I looked at was 3geez. Slammed on tokicos, limo tint and an axle back when I bought it, wish I wasn't dumb and lost it when I was 17.
 
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