Post
by MACK » Wed Apr 10, 2019 9:58 am
Smartbear wrote: ↑Wed Apr 10, 2019 9:36 am
MACK wrote: ↑Wed Apr 10, 2019 8:55 am
road warrior wrote: ↑Tue Apr 09, 2019 9:05 pm
I am aware I have a powerloss since the dlv back box but I don't mind too much, the noise is worth the slight drop so that's fine, but it might affect something like the blip with all the gurgling and noises going on.. If an engine is a musical instrument, then....
Has anyone else noticed a drop in power with a fettled backbox or an aftermarket one? I've seen some chatter about this being a potential issue with a backbox delete but nothing about it also being an issue with modded backboxes or aftermarket ones etc
I really don't see how straight piping the backbox with the same diameter pipe as the rest of the exhaust would reduce gas velocity and consequentially effect scavenging etc. If anything the design of the standard backbox with its lack of any real internal piping would act as a restriction, reduce gas velocity and scavenging. Its not like folks are suddenly sticking a 4" full system on, so gas velocity is reduced
It’s probably going to reduce back pressure with a straight piped rear box which will have an effect on torque, there was a link on here a while back from M3 cutters where someone had dyno tested there car & found it 20-30bhp down with a modded back box
Rob
Interesting result, but that said the M3 backbox is piped entirely differently to a 3.0i/si as standard so I'm not too sure its a fair comparison. I did give this a lot of though before modding mine and personally I've always thought that the non M E85/6 backbox's lack of internal piping, with all the gases forced to travel through the wadding is primarily about noise reduction and that it actually causes a big restriction to gas flow so would damage exhaust gas velocity and as they're intrinsically linked scavenging/vacuum (or back pressure as its commonly know). At the end of the day the trick is to have pipework big enough to get all the gases out whilst maximizing gas velocity. Go too big and you screw this by slowing the gas velocity down
I guess if a modded back box is actually hurting performance in some way due to its straight through perforated pipe design then the same has to be said for the plethora of aftermarket backboxes out there as they all follow the same basic design principle.
Silver 05 3.0i SE
Mods inc - F/L Xenons Clear Ind Rear Lights M Sport Seats & Wheel Eibach/B4 3.64 DIFF (SOLD)
White E89 20i M Sport
Mods inc- B12 kit, M3 Arms, 18" Zito 935's with PS4's, Decat & Remap, Switchable Exhaust Flap (SOLD)