What?

[Stretchomatic]

ha sorry bout my reply before, i'm only used to the ones the losers around town have on their old dattos, dunno wat they did to them but made a hell of a racket and could hear the backfires from ages away...i just compared them to cannons cos these ones just made a lot of useless noise and not much else...but now i know that they are usefull (when used properly)

cheers...

 

[bangers]

they help to keep backpressure which helps low end torque.

 

[MBS206]

they help to keep backpressure which helps low end torque.

OH BULLSHIT!

Backpressure robs you of power. Takes more effort for the engine to get the air out.

It's easier at low RPM for it to push it out, then at High RPM, therefore, you actually jsut get a larger drop of torque at the top end, over what you do down low. Hence it seems like more low down torque, because you robbed topend of what it can truly make

Power band is affected by Cam profile, and type of headers/extractors you have and inlet runners.

 

[stocky]

OH BULLSHIT!

Backpressure robs you of power. Takes more effort for the engine to get the air out.

It's easier at low RPM for it to push it out, then at High RPM, therefore, you actually jsut get a larger drop of torque at the top end, over what you do down low. Hence it seems like more low down torque, because you robbed topend of what it can truly make

Power band is affected by Cam profile, and type of headers/extractors you have and inlet runners.

you have a 3 inch exhaust, dont you?

 

[AirStrike]

OH BULLSHIT!

Backpressure robs you of power. Takes more effort for the engine to get the air out.

It's easier at low RPM for it to push it out, then at High RPM, therefore, you actually jsut get a larger drop of torque at the top end, over what you do down low. Hence it seems like more low down torque, because you robbed topend of what it can truly make

Power band is affected by Cam profile, and type of headers/extractors you have and inlet runners.

He said torque not power you tool!
You are quite clearly an expert on the topic, with your very accurate and descriptive explination of 'how its pushed out'.
Yes a larger exhaust might be better for power, but no back pressure will dramatically drop low end torque, which is more important.
AirStrike :air:

 

[MBS206]

No back pressure will increase torque across the whole range...

Try it seriously...

Get on a dyno, do a power run or two.

Then go, take your exhaust off, dial in a slight bit more fuel, and nock a touch more ignition advance in.
You'll notice torque jump across the whole range...

And torque is directly relational to power.

And no, i don't have a 3 inch exhaust.
Going too large of an exhaust is actually bad also, you'll increase back pressure again.

But, I hear you all cry, "That's impossible! It's a larger pipe!"

The problem being, in a larger pipe, back pressure is actually increased as since there is a larger volume to fill, and only the same amount being pumped out the exhaust, the actual velocity of the gas travelling down the pipe is slower.
By the time the gases hit the end of the exhaust, they've cooled down that much, they've condensed, and slowed down even more as that same molar volume of gas, no longer fills the same physical volume.

And your power band, is effectively where you have the best amount of torque (Since power = RPM*Torque/a constant) (Constant changes depending on units used for torque and power)

If you put on such an exhaust which you claim is bad, then go and get a tune, and put a touch more fuel in down low, and a touch more ignition advance in, you'll gain your "missing" torque back also.

When exhaust gases are suddenly allowed to flow more freely then they were tuned for, the tune leans out, and needs either: More ignition advance, or more fuel, or BOTH.

Yes, this post is a bit jumping and rambled... I'm tired...

 

[AirStrike]

No back pressure will increase torque across the whole range...

Try it seriously...

Get on a dyno, do a power run or two.

Then go, take your exhaust off, dial in a slight bit more fuel, and nock a touch more ignition advance in.
You'll notice torque jump across the whole range...

And torque is directly relational to power.

And no, i don't have a 3 inch exhaust.
Going too large of an exhaust is actually bad also, you'll increase back pressure again.

But, I hear you all cry, "That's impossible! It's a larger pipe!"

The problem being, in a larger pipe, back pressure is actually increased as since there is a larger volume to fill, and only the same amount being pumped out the exhaust, the actual velocity of the gas travelling down the pipe is slower.
By the time the gases hit the end of the exhaust, they've cooled down that much, they've condensed, and slowed down even more as that same molar volume of gas, no longer fills the same physical volume.

And your power band, is effectively where you have the best amount of torque (Since power = RPM*Torque/a constant) (Constant changes depending on units used for torque and power)

If you put on such an exhaust which you claim is bad, then go and get a tune, and put a touch more fuel in down low, and a touch more ignition advance in, you'll gain your "missing" torque back also.

When exhaust gases are suddenly allowed to flow more freely then they were tuned for, the tune leans out, and needs either: More ignition advance, or more fuel, or BOTH.

Yes, this post is a bit jumping and rambled... I'm tired...

Of course you would make more torque if you advance the timing and add fuel! That would make more power regardless of what components make up the exhaust.
AirStrike :air:

 

[minux]

Well, when i get home i will try and find the old dyno from my blown VN SS. We ran it header's dumped and tuned it so, then same dyno retuned to match exhaust(twin 2.5 inch straight), the torque range and power range was much better zorsted.

 

[bangers]

of course a blown V8 is gonna have a better torque curve if its tuned to suit the exhaust. If you wanted better torque out of your VN SS you should have stroked it. Then blown it.

 

[AirStrike]

of course a blown V8 is gonna have a better torque curve if its tuned to suit the exhaust. If you wanted better torque out of your VN SS you should have stroked it. Then blown it.

If you read what minux posted he said they ran it straight pipes, tuned to suit, then ran an exhaust an retuned it to suit that and it made more power and torque with the exhaust. Also why are you telling him to stroke it? We arnt talking about anything like that at all.........
AirStrike :air: