exhaust silencer

[linedriver]

my current exhaust is quite loud and can wake up the dead. i know that the resonator has to be replaced and i will be getting it done soon. in the event it is a bit loud still, i might be putting on a silencer. will the silencer wreak havoc on my powerband from the back pressure?

[Dragon Humper]

A little drop in HP yes, havoc no. I feel about a 30 to 40 HP loss with my silencer. That based on 550hp worth of air coming out of the tail pipe. I will gladly take a HP hit for the sweet silence it brings. The drone was killing me. WOT sounds like war though .


Jon.

[GTR-Dad]

If you change the back pressure you will also affect the volumetric efficiency which will affect your fueling.

Pay attention to your wideband to avoid leaning out issues.

Cheers,
Dan

[linedriver]

If you change the back pressure you will also affect the volumetric efficiency which will affect your fueling.

Pay attention to your wideband to avoid leaning out issues.

Cheers,
Dan

im a car with strictly bolt-ons that ran great with my very first exhaust and my HKS super dragger, will a change in back pressure with my new exhaust cause it to lean out?

at full boost, i think it was running at 13:1 for my AFR, but im not sure how precise AEM would be with their wideband:-o

[mcfly]

That's too lean for a turbo car
Playing with fire

[Skym]

From what I understand reducing backpessure raises boost level, due to internal wastegate design on turbo that can't dump enough exhaust gas quick enough, which makes boost rise at lower rpm's and boost spikes at higher rpm's. The rise in boost level leans out A/F ratio, as injectors are still injecting the same amount of fuel. You'll need to retune ECU to make injectors inject more fuel. Also make sure your fuelpump is not on the way out or have a clogged fuelfilter.

You can bore out the wastegate hole on back of turbo and fit a bigger flap to get better boost control. Or fit a boost contoller to control boost spikes.

You want 11.6:1 as a safe A/F ratio. Seen some push to 12.0 max on stock engine but I would play it safe.

[linedriver]

perhaps my wideband is not as accurate as i think it would be. its been running like that since i got it a few years ago. even when it got dynoed at apex modified when it was open, the AFR was around the 13:1 mark as well.


perhaps ill change my fuel pump soon, if the AFR changes, maybe it was just on its way out