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Lodgy
P Plater
68 Posts
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 Posted - 04 Nov 2010 : 12:18:27 AM
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gday everyone,
once again i am back looking for some better fuel economy.
i only have one question now, and it should be quite simple to be answered.
Why can i find an endless supply of chips on ebay for my vn which make them go harder and remove the limiter, and i cannot find a single one made to just increase fuel economy.
I have heard of foamy's tunes, where it says you may get up to 25% better fuel economy with the extra power you get(thats if i didnt just make that up) so obviously they can be tuned for it, but why will no body do it?
Sorry if im not making much sense, i am quite tired right now.
Thanks.
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Mechknight73
National Driver
1001 Posts
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Posted - 04 Nov 2010 : 6:42:48 PM
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| There is a basic thing you can do that will improve both fuel economy and power at the same time; fitting headers, and a free(er) flow exhaust. You don't have to make it loud for the headers to work. With less back pressure, the engine doesn't have to work as hard to push exhaust gases out. It will cost you slightly more than a reprogrammed chip, but will improve things overall. |
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Lodgy
P Plater
68 Posts
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Posted - 05 Nov 2010 : 12:51:07 AM
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| yeah ive got a cat back 2.5 but that only cost me 100 dollars, but i dont think ill be finding cheap extractors any time soon, plus there doesnt look like theres much room to move in the engine bay to take the stock headers off |
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Mechknight73
National Driver
1001 Posts
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Posted - 05 Nov 2010 : 10:26:41 PM
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| Even a cat back system will improve fuel economy. If the cat itself is new this will also help. Over time, a catalytic converter will become clogged. The only way you'll know about it is if the engine is lacking power, but everything else seems ok. |
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Lodgy
P Plater
68 Posts
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Posted - 07 Nov 2010 : 4:35:48 PM
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| yeah i was wondering about my cat, the VN did lose a bit of down low power a month or 2 back but we decided it was the auto slipping in lower gears |
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Mechknight73
National Driver
1001 Posts
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Posted - 07 Nov 2010 : 7:41:19 PM
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| Other than a lack of power, a clogged cat will show no other symptoms at all. It will still idle and accelerate smoothly, it will just be down on power. |
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lovevncomms
Fully Licenced
125 Posts
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Posted - 11 Nov 2010 : 8:37:03 PM
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| yeah have to agree with you both i am thinkin my cat is either blocked or on the way out power has dropped in grunt but still goes smooth so idk and yeah catback does a nice job on fuel eco if you add a cai will help too :) |
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Mechknight73
National Driver
1001 Posts
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Posted - 13 Nov 2010 : 3:43:40 PM
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| Let me preface the following by saying it's illegal, but it will tell you whether the cat is the problem; inside your cat is a honeycomb of the material that catches the pollutants. Undo the exhaust just behind the cat, and chip a hole though it the diameter of the exhaust. Seal the exhaust again, and take it for a drive. If you notice a marked improvement in power, then you know for sure that this was the problem. Then simply buy a new cat, and bolt it on as per factory spec |
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andrewpapa
Fully Licenced
122 Posts
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Posted - 17 Nov 2010 : 04:10:04 AM
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get lpg gas on it and your running costs will be (f.a) i did and i have not lost power i have more POWER ON AND LPG AND IT burn faster and has more octane-booster in it so you get more power if its tune right on a DINO -TUNE !!!,it is dry a fuel but you run it on unleaded fuel for 1 or 2 minute and then go to run it STRAT ON LPG . i am very happy with my LPG on my vn v6
5speed manual with mods. the cat converter mod is a mad mod to do for power taking internals out just don't tell no everyone its illegal too do mate !!!! i did it but my vn v6 5speed manual but i run it only on LPG gas that mod gave me the most power for a fee mod but don't do this mod if you run car on unleaded fuel only it is illegal too a do- $10,00.00 doller fine so don't tell everyone you don't know if police reed this or the R.T.A .top mod for more free power from vn v6 and v8s ( BUT IT IS ELIGLE TOO DO ON UNLEADED FUEL )SO DONT TELL EVARYONE KEEP IT A KEEP IT A SECRET SO YOU DONT GET BUSTED thy only cost $30.00c second hand CAT CONVERTOR and replass it befor you go to the (pits for blue-slipes!!! ) . IF your CAR HAS TO GO TO THE PITS FOR REGO HAVE A SPERE STOCK
ONE NOT MODED and repass it befor you go to the pits SO YOU DONT GET BUSTED AND COP THE PHINE ($10,000.00C)f**KEM just KEEP IT A SECRET AND YOU WONT GET BUSTED LOL!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!and i get better fuel econinemy lol
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i am not a licenced mechanic but i do have years off experience fixing and restoring cars and doing them up ,i can even do-motors-up,panel betting,spray painting,electrical work. i know What i am doing when fixing my cars, i am not saying i know everything on how to fix cars but i can fix them with information and help off the internet and this site.vncommador.com |
Edited by - andrewpapa on 17 Nov 2010 04:39:47 AM |
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andrewpapa
Fully Licenced
122 Posts
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Posted - 17 Nov 2010 : 04:57:58 AM
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you have too reset the computer and do are re-tune for best results after you do this mod your car will not run right until you do a reset the to tee ecm and then your set with more free power on a vn v6 or v8s this mod works on both but you have to do a re-tune fist ok i have done to booth v6 and v8s and end result more free power
but eligible just on unleaded fuel ok .i have warned you ok the fine is ( $10,000.00 )the fine mite me even more but just dont get bustedn ithe first places - be mart and repals it first so you dontget busted f**kem !!!
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i am not a licenced mechanic but i do have years off experience fixing and restoring cars and doing them up ,i can even do-motors-up,panel betting,spray painting,electrical work. i know What i am doing when fixing my cars, i am not saying i know everything on how to fix cars but i can fix them with information and help off the internet and this site.vncommador.com |
Edited by - andrewpapa on 17 Nov 2010 05:06:39 AM |
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Mechknight73
National Driver
1001 Posts
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Posted - 18 Nov 2010 : 5:31:00 PM
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| I had a frien with a VL that had the honeycomb on his cat melt. The diameter through the cat was only about an inch. He did tend to drive it hard though, especially on Lake Lefroy, a huge salt lake. It had Genie headers, and we think that this, coupled with his driving style was what finished off the cat |
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Mr Persistant
P Plater
72 Posts
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Posted - 18 Nov 2010 : 8:29:23 PM
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I don't have a high opinion of the stock Cat's ability to take even a few redline bursts in 1st gear on a regular basis. I think I mentioned it here before..the packing that holds the rear half of the honeycomb in place became dislodged on my relatively 'new' cat, and part of the honeycomb started rattling around. 
I think I can actually *hear* the back-pressure "BOOF" noise near red-line which I think is caused by the std exhaust being a little overly restrictive at peak rpm, possibly caused more by the rear muffler than the cat itself. Either way, I think this is what contributes to the cat's shorter life expectancy with higher rpms. It's irritating, but I still prefer the std, quiet, system over a more aggressive sports sound that draws unwanted 'attention'. 
The original cat before that one, though, was melted and crumbled into large chunks, badly blocking things. As mentioned above, it ran okay at idle & at city, commuter traffic speeds...but anything more than that and it felt like a major ignition system breakdown - that's how badly the exhaust was getting choked.
If you take the cat right off, you should be able to look straight through the honeycomb, from one end of the cat to the other, almost like there's nothing in there to impede your view. IMHO, it's worth keeping the STD bolt-up(Vs weld-on) Cat (with bolt-holes on the flanges either end) so you can easily remove, inspect and do 'whatever' else to the cat. |
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Mr Persistant
P Plater
72 Posts
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Posted - 18 Nov 2010 : 8:48:12 PM
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Speaking of Cats, do you reckon the following is really what it says it is? ie, BETTER than a std cat? Bit more free-flowing, can handle more abuse?
http://cgi.ebay.com.au/commodore-vn-vs-highflow-catalytic-convertor-/230542145778?pt=AU_Car_Parts_Accessories&hash=item35ad61f8f2
The name Redback is familiar, but I don't know much about them. Price is good even compared to an old Repco price for a std. Cat. Externally, it's the same as stock - solid. What's inside is where the std cat can use some improvement, simply from a durability perspective.
I AM currently "Legal", but mildly concerned, if you know what I mean...(where's the whistling-while-rolling-eyes smiley-face icon when you need it?) |
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Mechknight73
National Driver
1001 Posts
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Posted - 18 Nov 2010 : 10:37:15 PM
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| It's possible this one is more rugged than a stocker. If I remember rightly, Redback do make performance exhaust components, so they could just be a "heavy duty" version |
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voodoo92
Fully Licenced
150 Posts
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Posted - 19 Nov 2010 : 6:48:59 PM
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| when i recently wrecked a crappy vn i found it had a high flow cat n it. naturally i slammed it onto my beast. sad thing is i cant drive it yet so i couldnt tell anyone about the improvment or lack thereof. |
Bassist by day, VN nut by night |
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Lodgy
P Plater
68 Posts
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Posted - 23 Nov 2010 : 2:53:16 PM
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hey guys, thanks for the information, i decided to finally check out my cat, pretty simple because all it took was 5 minutes to take off and a tad longer to line up and put back on.
The only problem was that the cat is blocked, as suspected. When i first got it off i could only see light through about the size of a 5 cent coin.
I was wondering what i could do to possibly clean it so i got the pressure washer and stuck it in each end one after the other for about a minute each. For the whole time i was spraying the cat there was black water coming out of the other end.
I didnt think this would of actually done much but obviously getting the black **** out helped because there is now about a 20 cent size i can see through 
This is obviously not much of an increase but i can actually feel the motor stressing a little less, which means i should go and buy a new one and feel the difference.
i got a price off of a local carline mufflers for 220 for a high flow cat, does anybody do repro ones for a lower price?
Gee lately ive been posting with more words and effort than i done in my year 12 exams a month ago :) thanks for listening. |
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Mechknight73
National Driver
1001 Posts
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Posted - 23 Nov 2010 : 4:49:22 PM
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| Given the state of your present cat, even a stocker would be an improvement. If it has "HOLDEN" stamped on it, it's guaranteed to be more expensive than any aftermarket manufacturer. I would call a variety of exhaust places, and see what kind of prices they give you. |
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M3ZZA
P Plater
77 Posts
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Posted - 11 Jan 2011 : 8:19:45 PM
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Ok to warn anyone it is highly illigal and the EPA would absolutely a**e rape you with a $10.000+ or imprisonment so i would not recommend it. Plus gutted cats sound tinny rattly and plain crap. So for a good legit exhaust note a 150cell highflow 2.5 cat is the way to go or a 3 inch one incase you decide to turbo or supercharge to save on future costs.
$200 on ebay. plus postage is better then a $10.000+ fine or jail time. Plus think off the damage your doing by driving around with nothing to stop the pollution. 100% harmfull gasses nothing to stop half the nasty's. If you have kids think off the future consequences off the air they will breath.
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Modifying a car is like a drug once you start you cannot stop. |
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