Power and more of it

Bonz.
You are on the money. There is an increase in niose, but very little else if you just fit a bigger pipe. In Trucksters case he has a turbo so that is a different story. Eric.

The larger exhaust doesn't usually give much more of an increase of absolute power. What it does do, is allow the turbo to spool up faster which in turn changes your torque curve usually allowing more power earlier in the rev range so that by seat of the pants driving, the response is improved.
Regards Andrew.

Bonz,
With a smaller exhaust the exhaust gas back pressure is greater so more waste gas remains in the cylinder after each power stroke, a larger exhaust allows the waste gas to escape easier, with a turbo you are again forcing more air into the cylinder, this in turn pushes more waste gas out and depending on the camshaft profile may keep the inlet valve open to get a greater volume of air into the cylinder which mixes with the fuel vapour creating a bigger bang, more heat, more power etc etc etc Hence why racing motors have no mufflers and exit the constraints of a pipe as soon as possible, they want all the waste gas and some fuel out into the pipe hence the backfiring you hear of unburnt fuel flashing off in a hot exhaust on the overrun. Does this help at all????? Keep the shiny side up

Bonz

The other replies have spoken about getting the air (exhaust) out .Getting the air in will also help. Fitting a snorkel will help force air into the turbo and there fore increase torque.

I did notice an increase in torque, when driving on the sand dunes at Stockton Beach , after the exhaust was increased to 2.5", the new exhaust had a lot of the bends taken out and all the mufflers removed.

WayneAlways Out'N About

Bonz,

I was once told for power " there is no substitute for cubic inches"

I know it is not politically correct but cubic centimetres has not got the same sounding impact.

WayneAlways Out'N About

I have had a 2.5" exhaust on my Triton 2.5td for some time together with a straight thru muffler and the fitter did a great job in minimising bends.
As advised the turbo acts as something of a muffler so the noise level is only slighlty increased, low speed torque is improved a little, but top speed remains about the same but this may be due to gearing & engine characteristics I feel.
It cost me $250 but the pipe used was thin & probably resonates a bit. I would go for a heavy guage pipe & muffler if possible & probably greater life.

Best way to think of an engine is as a big air pump.. gas in / gas out. Atmospheric pressure will push gas into an engine but the exhaust stroke of the cycle has to 'push' the gas out so to speak. of course the gasses are hot and therefore expanded, so they will need to move at speed to evacuate to combustion chamber. Exhaust headers are designed to 'scavenge' the gases and help remove combusted gases from the chamber to allow for more fresh gas on the next cycle. The exhaust pipe should be of a large enough diameter and minimising any sharp bends , the bends should be mandrel bent as this does not decrease the internal diameter of the pipe and reduces frictional losses from the bend. With turbos, go for an incresed diameter from the outlet flange onwards, with an internal divider for the wastegate gases. For max power use a custom header manifold as well ( $$) upgrade turbo etc ($$$) There is also a lot of thermodynamics involved but i'm sure as hell not going into it here. lol. Hope that didn't confuse too much.Just killin time till easter...............go and play in the dirt, instead of workin in it......