New Exhaust - Suggestions?

[mulligan-can]

Ok, I know almost nothing about exhaust systems.

I'm planning on getting a new exhaust and a set of extractors. Anyway, what sort of setup should I be looking for?

Oh and could you please explain just what you mean when you say '3" twin catback with no muffler'

I know a muffler makes it quieter (do they impede flow at all though?) and that cats at catalytic convertors and they remove soot, unburnt fuel etc and do impede flow.

Anyway, car's a stock v6 vn s1.

Thanks

[pandaman]

For a standard V6, you've got one real sensible choice. A 2.5 inch catback system for starters. That's a 2.5 inch pipe from the catalytic converter back. There are a few brands of these that are available as an off the shelf system, redback, lukey and another one I can't remember. Most of them come with a muffler and a resonator. A muffler does impede flow, but it's kinda necessary if you wanna keep it legal. The resonator provides very little impedance to flow, they're not a bad idea if you like your sanity though sa the idea of a ressie is to prevent droning at cruising RPM.

A good catalytic convertor isn't a big restriction, also necessary if you wanna keep it legal. Basically no reason not to run one. If it really concerns you, you could shell out for a high flow cat.

Extractors are also a good idea, adds a fair bit of expense but they can give a real nice crackle when you back off and there's the whole extra power thing.

[mulligan-can]

ok, well, i have the original cat in there still. the system was replaced from the cat back by the prevrious owner with a standard 2.25" system.

would the cat still be any good? oh and new extractors would replace everything up to the cat right?

[pandaman]

ok, well, i have the original cat in there still. the system was replaced from the cat back by the prevrious owner with a standard 2.25" system.

would the cat still be any good? oh and new extractors would replace everything up to the cat right?

The original cat might still be ok, but an aftermarket high flow cat would definitely flow better. Extractors aren't quite everything up to the cat, there's a Y-piece which merges the extractors into the cat.

[Not_An_Abba_Fan]

On a VN most extractors come with the Y pipe and they replace everything from the heads to the cat. If the cat concerns you, get the exhaust shop that does the job to test it while they have your car, it's a simple temperature test and it will tell if the cat is working or not. Do not put a hi flow cat on as these do not work on standard cars. It will improve the flow but will not give any benefit unless you have a high performance engine or you intend to race the car. If your car is an automatic I would recommend a small perferated tube hotdog be fitted on the rear to eliminate droning. There are numerous brands of exhaust systems, but the best combination is a 2 1/2" mandrel bent from cat back, make sure the front muffler is a straight through glass pack design and tail pipe without a resinator if it's a manual. Doesn't really matter which extractors you fit, although Pacemakers are the best flowing, Lukey and Advance are probably the cheapest. You should expect to pay around $800 for extractors and your exhaust give or take.

[pandaman]

Do not put a hi flow cat on as these do not work on standard cars. It will improve the flow but will not give any benefit unless you have a high performance engine or you intend to race the car.

And exactly how did you pull that conclusion out of your arse? There may not be an awful lot to be gained by running a high flow cat, in fact if the standard one is in good nick I wouldn't bother either. If it needs replacing though theres no good reason not to use an aftermarket high flow item. Especially given that if you shop around they're not too much more expensive than a bog standard one.

[Not_An_Abba_Fan]

A cat converter is designed to work at a certain temperature. The internal design has not been configured without extensive research. The flow characteristics keep enough heat in the catalyst for it to work without sacfricing exhaust flow. If you put a higher flowing cat on without having a higher performance engine or without maintaining a high enough RPM to keep the catalyst at optimum temperature it will not work. The same principle with an oxygen sensors, they work on temperature, too high a flowing an exhaust will not retain enough heat for the O2 sensor to give the correct signals.

[mulligan-can]

Speaking of which where about is the o2 sensor? i have a feeling mines dead....

Ok, so you reckon about 800 for extractors + 2.5" cat back? that would be installing myself right?

any estimates on the price of a new cat? for worst case scenario

cheers

[Not_An_Abba_Fan]

That price is fitted, parts only would be cheaper. I think the O2 sensor is in the engine pipe just down from the manifold or VN, it could be where the Y pipe comes together just in fron of the cat. Cats will vary depending on where you get them but should be around the $200 mark, sometimes cheaper. The easiest way to tell if a cat is not working is to do a temperature test, looking into it won't tell you much unless its melted, broken or blocked.

[mulligan-can]

wow, 800 fitted? haha, i think it would prolly be more around my area but anyway. i'd be able to fit it easily enough myself or with a mates/father help.

Alrighty so I should be able to get a quote of around 800 max for a set of extractors and 2.5" cat back.

Awesome. Thanks.

[anton1o]

Check out Thread dedicated to Modifcations

[pandaman]

A cat converter is designed to work at a certain temperature. The internal design has not been configured without extensive research. The flow characteristics keep enough heat in the catalyst for it to work without sacfricing exhaust flow. If you put a higher flowing cat on without having a higher performance engine or without maintaining a high enough RPM to keep the catalyst at optimum temperature it will not work. The same principle with an oxygen sensors, they work on temperature, too high a flowing an exhaust will not retain enough heat for the O2 sensor to give the correct signals.

The temperature of the catalytic converter determines the effectiveness of the catalyst, this is true. However, the temperature of the catalyst will have no effect on the performance of the vehicle. Also, I highly doubt that a 2.5 inch sports exhaust with a high flow cat is going to increase heat rejection to a point where the cat is too cold. If that were true, the vehicle would fail a basic emissions test and I have NEVER heard of a stock vehicle with a sports exhaust and a high flow cat failing on emissions, noise yes, emissions no. Hell if the cat were running too cold on such a vehicle, even a roadside check with an IR thermometer should give it away and I've never heard of that happening either.

[greenfoam]

Just remember you can make 105 rwkw on a V6 VN without spending any money. You can make up to 115 rwkw spending a grand on a V6. My VP 5 liter has a market value of $2900 and has 140rwkw stock as a rock so you have to think wisely about all this

[Cobez]

Extractors are also a good idea, adds a fair bit of expense but they can give a real nice crackle when you back off and there's the whole extra power thing.

pacemaker headers for my VP...........$600 inc labour i ever spent!! i always reckon the first 2 basic mods you should do on a VN / VP are extractors and exhaust!! first things i got were a mandrel bent 2.5" straight through exhaust and pacemakers.........

[Not_An_Abba_Fan]

The temperature of the catalytic converter determines the effectiveness of the catalyst, this is true. However, the temperature of the catalyst will have no effect on the performance of the vehicle. Also, I highly doubt that a 2.5 inch sports exhaust with a high flow cat is going to increase heat rejection to a point where the cat is too cold. If that were true, the vehicle would fail a basic emissions test and I have NEVER heard of a stock vehicle with a sports exhaust and a high flow cat failing on emissions, noise yes, emissions no. Hell if the cat were running too cold on such a vehicle, even a roadside check with an IR thermometer should give it away and I've never heard of that happening either.

How many tests have you performed on such vehicles? I will admit I have never done an emissions test, but in our workshop we have done IR temperature tests on a few different vehicles. It was interesting to see the temperature dropped by around 70 degrees, while this may not affect the emissions at running temp, but it certainly does at anything below 2000 rpm. With this amount of loss, it would also affect flow, which of course is increased reducing back pressure. Like I have been saying, on a performance vehicle or one that sustains high revs this would be a good thing, but on a street car it reduces its performance. A dyno will show in increase in peak kilowatts but nobody drives a car the way a dyno reads power and torque. My whole point of my post is that hi flow cats are pointless unless the vehicle or its use calls for it. There is no real justification for spending that money unnecessarily when it gives you no benefit.

[mulligan-can]

Just remember you can make 105 rwkw on a V6 VN without spending any money. You can make up to 115 rwkw spending a grand on a V6. My VP 5 liter has a market value of $2900 and has 140rwkw stock as a rock so you have to think wisely about all this

Woah. Ok. Cool. Any pointers on how you would go about doing that? I'm really new to anything involving car modifications I can drive em but don't know a tremendous amount about what goes on under the hood (more then a lot of people but not as much as 99% of the people on this forum)