2.5" Or 3" Cannon?

[Jack-]

I've got my exhaust system all sorted out except for the cannon. I've got HPC coated extractors from DKNE, and getting a custom 2.5" system made up, although unsure if I should go with a 2.5" or 3" cannon? What would be the difference in sound and what have you guys got?

[Oo oO]

go the twin tip having a cannon on will make it prolly just over the legal limit with the exhaust system on an NA, mines on 85DB... but hey its up 2 u lol

[KezR33]

Best to be safe.

Go for the 5"

[Jack-]

Best to be safe.

Go for the 5"

Yeah, thanks for the help

[ONE-VIA]

ive said it befor and il say it again

get flutes

cbf linking search on here should find something or jump on ns / google

[hr32gts]

2.5" should b good no use getting bigger im putting extractors n 2.5" on mjne was 97.8db b4 extractors just with 2.5" catback

[MUZT3K]

get a 3in, i had it on my 33 n/a sounded sick...109 DB lol

[mad082]

go 3", then you can be compared with lancer and excel drivers with stupidly big exhausts

[Jack-]

Which would sound better, less droney? and which for power (I know the difference would be minimal) ?

[(OO)SKYLINE(OO)]

For N/A don't go anything bigger than 2.5".

You could even get away with 2.25".

I had 2.25" on my Nissan 280ZX (2.8lt Striaght 6 SOHC) after full re-done engine with lumpy cams and it was great.

[N-DAWG]

Are you talking about the actual canon tip 2.5" or 3" or the whole exhaust system? If the whole exhaust system go with 2.5" for best all round gain. 3" catback will give you more top end, more noise, and less bottom end.

[Jack-]

No, I'm getting a 2.5" system, but I'm undecided on the cannon, whether to go 2.5" or 3"

[(OO)SKYLINE(OO)]

Cannon Muffler size you can have up to 4.5" or what ever size you want (Out Pipe) but the In Pipe must still say the same 2.5".

[Jack-]

Cannon Muffler size you can have up to 4.5" or what ever size you want (Out Pipe) but the In Pipe must still say the same 2.5".

Yes, I know, everything has been answered except my question - out of a 2.5" or 3" cannon what would be better?

[(OO)SKYLINE(OO)]

Yes, I know, everything has been answered except my question - out of a 2.5" or 3" cannon what would be better?

Stick to 2.5".

2.5" straight through all the way.

Cuz your car is N/A, nothing over 2.5" other wise you lose back pressure (There is the correct name for "back pressure" but I can't remember...)

This is only for straight bolt on.

You can have a larger size pipe if you want but will requirer tuning.

[Jack-]

Guessing 2.5" would be quieter too, yeah might go for that

[Oo oO]

+1

[N-DAWG]

Stick to 2.5".

2.5" straight through all the way.

Cuz your car is N/A, nothing over 2.5" other wise you lose back pressure (There is the correct name for "back pressure" but I can't remember...)

This is only for straight bolt on.

You can have a larger size pipe if you want but will requirer tuning.

Volumetric efficiency.

Think of it as drinking with a thicker straw vs a thinner straw. Thicker straw takes more effort to get the drink (less low down torque), but once it starts flowing you can get more drink (top end power). With a thinner straw little effort is needed to get the drink flowing (more responsive low down torque) but the flow reaches its peak quickly (limited top end power). The volumetric efficiency refers to time it takes for the volume of the straw to fill with liquid. In real world terms with a car, this higher top end power sacrifices response and low end power which for day to day driving is generally better.

To take that analogy to another level, if you were entering a drinking competition and you had to choose a straw, which would you pick? The larger straw as once you fill the straw with liquid, the liquid will flow a greater amount. Likewise, if you're car is going to see the track more often, or higher revs more often, then a larger exhaust pipe diameter would be ideal as the top end power outweighs the need for bottom end power and torque.

[4door_Sleeper]

Stick to 2.5".

Cuz your car is N/A, nothing over 2.5" other wise you lose back pressure (There is the correct name for "back pressure" but I can't remember...)

Volumetric efficiency.

Think of it as drinking with a thicker straw vs a thinner straw. Thicker straw takes more effort to get the drink (less low down torque), but once it starts flowing you can get more drink (top end power). With a thinner straw little effort is needed to get the drink flowing (more responsive low down torque) but the flow reaches its peak quickly (limited top end power). The volumetric efficiency refers to time it takes for the volume of the straw to fill with liquid. In real world terms with a car, this higher top end power sacrifices response and low end power which for day to day driving is generally better.

To take that analogy to another level, if you were entering a drinking competition and you had to choose a straw, which would you pick? The larger straw as once you fill the straw with liquid, the liquid will flow a greater amount. Likewise, if you're car is going to see the track more often, or higher revs more often, then a larger exhaust pipe diameter would be ideal as the top end power outweighs the need for bottom end power and torque.

Sorry to disapoint, but backpressure is never your friend - this logic is so 1930's

I agree that a large system may cause you car to run poorly down low, but this is a tuning issue rateher than a volumetric issue.

On an NA, the science is to get all of the harmoniocs of the exhaust right. When correct and you can scavenge extra exhaust gasses out (due to a low pressure region forming at in the exhaust near the open valve) and hence draw in more clean air/fuel mix. (mor clean mix in means more bang)

It was this technology that made Yamaha so succesful with their bikes after WW2. This was the result of a merger between a german motorbike firm (that shot through after the war) and Yamaha (who specialised in musical instruments and hence harmonics.) They succesfully cracked the technology.

This is also where terms like "tuned length headers" comes from.

For another example, consider drag cars, they have large, short exhausts to minimise back pressure. Whist I agree they run much of the time at close to full throttle, they still cant afford to have a sluggish bottom end as the race is over too quickly for any part of the engine not to pull its own weight (if you will excuse the punn)

So, to answer your original question, the cannon is only for asthetics, so it wont matter what you put on so long as it wont restrict the rest of the system. I would go for a nice 3" (again asthetics) but you may want to have them tack it first so you can give it a short drive and see if you like the sound (differens 3" cannons will sound different and be quieter or louder depending upon the internals,) so just because 1 is too loud, wont neceseraly mean they all will be.

[(OO)SKYLINE(OO)]

Volumetric efficiency.

Think of it as drinking with a thicker straw vs a thinner straw. Thicker straw takes more effort to get the drink (less low down torque), but once it starts flowing you can get more drink (top end power). With a thinner straw little effort is needed to get the drink flowing (more responsive low down torque) but the flow reaches its peak quickly (limited top end power). The volumetric efficiency refers to time it takes for the volume of the straw to fill with liquid. In real world terms with a car, this higher top end power sacrifices response and low end power which for day to day driving is generally better.

To take that analogy to another level, if you were entering a drinking competition and you had to choose a straw, which would you pick? The larger straw as once you fill the straw with liquid, the liquid will flow a greater amount. Likewise, if you're car is going to see the track more often, or higher revs more often, then a larger exhaust pipe diameter would be ideal as the top end power outweighs the need for bottom end power and torque.

Ah yeah... "Volumetric Efficiency"... That's it.

The straw analogy puts it in simple terms and very understandable.

Sorry to disapoint, but backpressure is never your friend - this logic is so 1930's

I agree that a large system may cause you car to run poorly down low, but this is a tuning issue rateher than a volumetric issue.

On an NA, the science is to get all of the harmoniocs of the exhaust right. When correct and you can scavenge extra exhaust gasses out (due to a low pressure region forming at in the exhaust near the open valve) and hence draw in more clean air/fuel mix. (mor clean mix in means more bang)

It was this technology that made Yamaha so succesful with their bikes after WW2. This was the result of a merger between a german motorbike firm (that shot through after the war) and Yamaha (who specialised in musical instruments and hence harmonics.) They succesfully cracked the technology.

This is also where terms like "tuned length headers" comes from.

For another example, consider drag cars, they have large, short exhausts to minimise back pressure. Whist I agree they run much of the time at close to full throttle, they still cant afford to have a sluggish bottom end as the race is over too quickly for any part of the engine not to pull its own weight (if you will excuse the punn)

So, to answer your original question, the cannon is only for asthetics, so it wont matter what you put on so long as it wont restrict the rest of the system. I would go for a nice 3" (again asthetics) but you may want to have them tack it first so you can give it a short drive and see if you like the sound (differens 3" cannons will sound different and be quieter or louder depending upon the internals,) so just because 1 is too loud, wont neceseraly mean they all will be.

I see...

So basically if your N/A car sees a lot of track of track days with plenty of full throttle, still a larger diametre exhaust will well a lot at top end, but keeping in mine not to sacrifice low down.

So in Jack- 's case if it is just for street / daily 3" still ok?

Thanks for that info fellas!