Anyone regretted gutting the exaust?

Discussion in '6th Generation 2002-2013' started by Molsan, Nov 4, 2008.

  1. powerslave

    powerslave New Member

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    I have to agree with Qkchk 100%,
    -Gut your pipes completely!
    The pipes look completely stock, you reduce wieght substantially, and the bike snarls and barks like a '60's muscle car!!!!

    :vtr2:
     
  2. havcar

    havcar New Member

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    What's up guys!

    Just wanted to say one quick thing here. The thing that nobody is talking about regarding a gut of the stock exaust is the fact that it's going to mess with the bikes compression. This is going to throw the bikes CPU/ECM way off. That can lead to many problems one of which is a seriuos amount of "knocking" from the pistons.

    In point, just listen to the clip provided by hondawolf during his return run while he's idoling on the shoulder. His bike is knocking hard. Yes everything sounds good up untill then, but gentlemen, piston knocking and compression issues will turn into a serious problem at some point.

    I don't want to be a party pooper but this is not a great mod to make unless sound is the only concern. If you do do it, then certainly consider changing your fuel mapping.

    Best luck!!
     
  3. powerslave

    powerslave New Member

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    My bike has been running perfectly for the past year. I think if one gutted the cat and the pipes there may be fueling issues.
    BTW-yeah, sound is the only concern with this mod, nobody is claiming or expecting big hp gains.
     
  4. chickwebb

    chickwebb New Member

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    Uh, no. I have run mine both with and without the fully-gutted pipes and there is NO discernable difference. It runs just fine either way - No PCIII, no mods other than the O2 sensor eliminators. On the street, on the track (both with the stock pipes and with the gutted ones), NO difference.

    I bought the bike with stock pipes, then bought a set of "properly" (i.e., opened, cut, and welded shut) pipes from a fellow VFR owner here in the SFBA.

    I run with the gutted pipes on the street and on the track, except at Laguna Seca, where the noise restrictions force me to put the stock pipes back on. I should say, "ran", though, since I don't plan to take the VFR out to the track anymore. When I did, though, no issues. Bike ran fine. No knocking or pinging. Same on the street., regardless of the fuel that I buy.

    This is easier, cheaper, and just as effective (in terms of exhaust note) as putting on any of the aftermarket pipes, IMHO. Yeah, you can get louder (2Bros), and mellower (Staintunes), but this is a great mod and I highly recommend it. Best value for the $$.
     
  5. havcar

    havcar New Member

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    Uh...yes! There is no way to mod your exaust whether it be after market or a gut job, that does not effect the bike. A gutting will do damage. It may not happen in 1000 miles or even 10,000 miles but it will damage your bikes' longevity. In fact, if you go talk to a mechanic he'll tell you same thing.

    While an after market pipe does very little for horsepower, a gutting of the stock pipe can actually cause a decrease in HP, make the bike run rich etc, and yes it will cause some knocking. All you have to do is listen to hondawolfs link to know that I'm not talking out of my ass.

    That said, none of these bikes are mine and I couldn't care less about what somebody wants to do to thier ride. Just some info for those thinking about it!
     
  6. powerslave

    powerslave New Member

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    FYI:
    Our bikes are fuel injected and can compensate for what little effect the gut job has on air-flow.
    I, like many others also run an aftermarket air filted with no adverse results.
    BTW, I couldn't hear any "engine knock" on hondawolf's bike over the sound of that wicked exhaust system!!!
     
  7. havcar

    havcar New Member

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    FYI:
    Our fuel injection is based on very specific mapping which the ECM controls. The ECM does not make adjustments for any mods nor does it compensate for anything unless you tell it too! I.E. 02 eliminator, PCIII etc. A gutted exhaust is no little effect.

    Air filters are a totally differant story.

    Look, I'm not trying to be a dick or disperage anyone for their choices in mods, because I really don't care. Just talk to a salty mechanic and see what they say!
     
    Last edited: Feb 5, 2009
  8. PhatPat33

    PhatPat33 New Member

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    I love the sound of mine. I do have a stock set in the garage if I do need it. I found a stock set on Ebay for a great deal to use as a back up.
     
  9. powerslave

    powerslave New Member

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    So, the computer can't adjust for air temperature or altitude?
     
  10. chickwebb

    chickwebb New Member

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    No, it can. The 6th Gen ECU takes inputs from the throttle position, coolant temp, intake air temp, barometric pressure, intake manifold pressure, and 02 sensors. So, it does adjust for temperature and altitude, among other things.

    Havcar is correct in that, if you change the exhaust/headers/air filter/etc. you will make modifications to the performance of the engine that the ECU cannot compensate for.

    That is why you need a PCIII or similar; once properly programmed it will modify the signals sent to the fuel injectors to compensate for the mods. Some mods make a big difference, some mods make a smaller difference. In many cases (exhaust, for example) can be made without there being discernable changes in engine performance.
     
  11. chickwebb

    chickwebb New Member

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    Technically correct, though you're attempting to refute a point that I did not make. What I said was that the difference between stock and gutted pipes is not discernable.

    This has been my personal experience. Back in the day that counted for something. Maybe times have changed... But, I maintain that putting on a set of aftermarket pipes or gutting the stock pipes will probably not result in any noticeable change, positive or negative, in the performance of a 6th Gen VFR.

    That said, when I put the gutted pipes on I'm sure there was a change and it may have been slightly negative. Could I tell? No. Will you be able to tell? I think probably not. Not unless your butt-dyno is considerably more sensitive than mine. Besides, let's say that you lose 1-2% of the performance of your 100 bhp VFR. Do you care, really? Do you really think that you are going to need/use those last couple on the street? I hope not. Even on the track there are few of us (myself included) that would notice the difference.

    C'mon havcar, you've had all the mods done (PCIII, K&N, 2Bros, etc.) and the bike dyno'd. I figure you spent at least $1500 on all of that. So, pony up. Show us your dyno results so we can see how much you've gained for the $$. Show us how many seconds you've shaved off your lap times.

    Me, I'd rather spend the money on more track days... on my RC.
     
    Last edited: Feb 6, 2009
  12. jev.

    jev. over there

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    I'm a bike mechanic and I'm telling you that you will not damage your bike if you simply gut the mufflers. You can even run it without the mufflers at all without adversely effecting it. Your neighbors would probably kill you, but it can be done(sounds wicked). There is not a lot of difference in running gutted vs. aftermarket pipes. I've had mine gutted since the bike had 300 miles on it and it's running fine 20k later.No, you're not gonna have a huge increase in power and yes you may have a drop in power, but you're never gonna be able to tell either way. And running gutted pipes WILL NOT cause knocking. I don't know where you got that but it's just plain wrong.
     
  13. powerslave

    powerslave New Member

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    As far as I can tell, gutting my pipes has not increased my power,
    so...It has not increased airflow through the engine,
    so...I haven't changed anything beyond the limit for the stock computer to calculate correct fuel delivery.
    Chick- I know the ecu can adjust for temp and altitude...that was meant to be a tongue in cheeck question, but I guess that didn't come through like I intended.:redface:
     
  14. chickwebb

    chickwebb New Member

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    Removing the baffles will allow the exhaust gases to exit more freely (i.e., less backpressure), so there is likely a very small positive effect on the engine's ability to "breath".

    Power production is more complicated than just making the engine breath better, though, and reducing backpressure can (and does) decrease performance, unless you tweak the fuel delivery as well. Your bike probalby lost 1-2% of its performance when you gutted the stock pipes because of this. I'll bet you didn't notice.

    The reason for the peformance decrease is that the fuel map in the ECU is optimized for the baffled pipe and the reflected wave that it generates. Removing the baffles (or putting on an aftermarket exhaust can, or removing the cat converter, or changing to straight headers, etc.) changes the amount and timing of the energy reflected back toward the cylinder, and the result can be a less-than-optimal mixture at certain RPMs.

    This is why you really need to get a PCIII and have the bike dyno'd in order to optimize performance after any of these mods. Note that one of the nice things about the PCIII is that a lot of people have them, and once you've tuned a bike with a certain configuration (this or that set of cans, plus a K&N filter, for example), you can upload and share the map with others who have the same configuration and they will reap the benefits of the money that you spent taking the bike into the dyno shop.

    Many people, myself included, have put on aftermarket cans or gutted exhausts because we like the way it makes the bike sound, think we're safer because we make more noise, etc. Whatever the reason, don't fool yourself and think that you're actually improving the performance of the bike (though it sounds like it's faster!) unless you're willing to go to the trouble of installing a PCIII and a proper map, or spending the money for some dyno tuning.

    Yeah, you're right. Tone is hard to detect in a post. My bad. Sorry.
     
  15. hondawolf

    hondawolf New Member

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    Hey guys thought this was getting interesting. First off, I've done 16,000 miles with the gutted exhaust. I'm currently at 39,000 miles on the bike. I had a shop do the 32K service, and a compression check. Everything came back within spec. I have not noticed any loss in power or gas mileage. I still get 50 mpg freeway, and about 45 mpg average on the weekend rides. I'm pretty easy on the bike and and it sees little time above 7,500rpm.

    As for concern for engine damage or the knock sounds. The bike made the rattling when I purchased it. As far as I could tell it was the infamous Honda clutch rattle. I've taken it to 2 different mechanics, one a dealer and they both said it was the clutch.

    Havcar, how does the lack of compression going to cause piston knock? Was curious if you could explain a little more. Not trying to cause trouble w/ anyone, just wondering since this is new to me. Thanks
     
  16. jondevos

    jondevos New Member

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    Gutting the exhaust will cause a very small decrease in back pressure. Nothing that I would be concerned about. I believe what Havcar was referring to was pinging or pre-detonation rather than piston knock. Piston knock is a complete different situation which is the result of wear to the engine. If a bike runs too lean then it will run hot. The heat in the cylinder can cause the air/fuel mixture to ignite or detonate before the spark plug actually fires causing the knocking or pinging sound. This is very harmful to an engine (Ive had a hole blown through a piston in one of my bikes, before I became a tech though). I plan on doing this mod to my 86 750 as soon as I get access to my bike again. I did it to my old ninja and it adds 500cc according to sound. hehe
     
  17. hondawolf

    hondawolf New Member

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    jendevos, I see what you mean. I do know what pre-detonation is and piston knock to me would be a loose/bad wrist pin on the rod. I have got the bike to "ping" a couple times, if I was under heavy load or nail the throttle from a low rpm. As for temps, my bike does not run a degree warmer with the exhaust the way it is. Well I will keep running the bike the way it is, if I ever have an issue that seems to be related to the exhaust, then I will alert everyone immediately.
     
  18. madmax3022

    madmax3022 New Member

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    just did the no weld-dremel cut method, took me around 2hrs and my "test ride around the block" took 1.5hrs.............. i LOVE IT!!! i couldn't get the smile off my face, it's better than the soundclips i found. Very impressed and will find any excuse to go riding now..... "need some milk babe? i'll just pop down to the shop........I know we have 2ltrs in the fridge but but but....."
     
  19. NOLA VFR

    NOLA VFR New Member

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    I did the dremmel mod a week ago. I read the posts on this mod - everything from no difference to engine damage. I left the stock exhaust manifolds and cat converter on the bike like most people. With a 4 into 2 into one (with a cat in line) I don't see how there could be drop in back pressure that would be enough to make a noticeable difference. The cat is the straw that the exhaust system is exhaling through. Many of the aftermarket cans are virtually straight through designs. As I did not do the full gut of my cans, there is still a limited degree of restriction (the same as the aftermarket cans).

    Like one poster said, I just wanted more tone without concern for noticeable power gains - one direction or the other. Further, it seems that at least two mechanics/technicians have stated that the gutting of the stock pipes will not harm the motor.

    I may switch to aftermarket cans at some point as I do like the look sound of the 2bros and Leos. If a mechanic/technician does post here stating that the gut-job is a bad idea, I’ll move a little quicker on the aftermarket cans. I’m just a “shade tree” mechanic that learned basic mechanical skills fixing my ‘66 Ford when I was a kid because I couldn’t afford to bring it to a mechanic (just asked mechanics for advice/direction). I therefore value the advice of those who turn a wrench or tune a computer.
     
  20. warrlac

    warrlac New Member

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    Gutted both the cans and the cat + PCIII

    I did my 2004 last year. I gutted the cans and then the cat as well. The headers have been HotJet coated (Ceramic).

    When I first installed the gutted system I was expecting awesome performance. I had downloaded a very aggressive (lots more fuel) map for the PCIII from the VFRD forum. It ran no better and was really fumey.

    I was disappointed.

    I then loaded a more conservative map (Cozey's Map) from the same forum. This time I got the results I was expecting. Runs clean and pulls HARD all the way up to redline. The VTEC transition is smooth but you get front wheel lifting power in 2nd gear.

    I feel that the mod was fairly economical in comparison to aftermarket cans alone. You really can't buy performance headers for these things without paying a ton of money.

    I so far no problems.
     
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