Sounds great mate lol.As a mere yoof I had a BMw 323 shark nose with an aftermarket back box( twas a black one, the zorst that is) and it sounded the dogs danglies with the straight six.
Plod stopped me (cos they were jealous, obviously, and had questions ready about stuff like Insurance/tax/affordability lol), they commented on exhaust note, I simply said to them how much paperwork is involved should we proceed down this road, lol, I waved to them gallously in my RVM as I squatted that suspension like only a 3 series can squat rear suspension, coupled to the exteme visual camber change I was king that day, ohhhh yesss I woz
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Needing back pressure in the exhaust is a load of bollocks. What you need to do is maintain the velocity of the gasses on the way out. Go too big and the gasses will slow down, which will create back pressure, slowly down extraction of exhaust from the engine. Keep exhaust gas velocity high and you get a low pressure behind the gasses which aides extraction. The issue of removing restrictions willynilly is it can reduce the efficiency of the exhaust by removing the vacuum effect which leaves more exhaust gasses behind, impairing extraction from the next cylinder.
No cats in the 80s, and no white dog sh*t on pavements either (never got to the bottom of that connundrum, pun intended
no middle box removal either, just whipped off rear silencer and fitted (Janspeed?) rear. Regardless of the sweet and purposeful sound it made I more than likely made it slower, which ironically gave me more time to savour the 4 barrel fed six. lol
Aye, pretty much everything that the world wanted to sell in the US.
Sorry, I wasn't meaning to sound like I was having a go at you, I just see "you need back pressure" a lot online and it is a daft statement. For some reason it is one of those daft "performance tips" that won't go away.
By having vacuum extracting exhaust gasses, overlap means you can draw in fresh air and have a cleaner cylinder for the next burn. Back pressure with overlap would force exhaust gasses backwards through the valves and result in a dirty burn. Not to mention slow down the flow of clean air.
The plenum chamber is of similar capacity to the engine. So there should be sufficient clean air without having to scavenge from cylinder to cylinder. If that isn't what you were referring to then I have no idea why you think having exhaust gasses back up into the cylinder is a good thing. But I am genuinely interested to hear why.
When the opposite bank is next to fire the low pressure behind the gas you theorised on is lost. The v6 (leaving aside the turbo) and v8 don't fire in a series of opposing banks.
