Vehicle & Technical > Defender
Straight thru' exhausts, are they....
robbie:
Me too.... but only when the weather warms up a bit :)
Eeyore:
As an interesting aside, a good friend of mine (in OEM powertrain*) did some calcs regarding the ideal exhaust bores for tubular systems. Apperently, as a quick and dirty, the ideal is about 1" of bore per 100 hp output from the engine. But this only works for petrol, apperently!
I didn't ask him about twin pipe systems.
Just a little snippet that might be helpfull for all our budding pipe benders out there! :wink:
cheers
8)
Eeyore
*He developed a cracker for Bentley that cranked out 800 ft/lb 'o' torque at tickover :twisted:
V8MoneyPit:
With due respect, I would suggest that this rule is a little over simplified. The system length, silencer size/design, bends in the system, head porting design, etc. all have significant effect on power output. The bore must vary depending on the other factors.
Results of tests on the classic Mini found a 1.75" bore system worked best for outputs from mildy tuned (say 50bhp) right though to over 100bhp. This is with a long centre branch manifold off the 3 port standard head (the middle port is siamesed). Once you get above about 110bhp, a 2" system flows better.
If 1" per 100bhp was standard for the OEM's, why do they all use bigger systems? Even a Polo develops near to 100bhp these days and it certainly uses a system bigger than 1". Equally, an 800bhp Bugatti would require an 8" system!!! Now that would REALLY like to see :lol:
Eeyore:
Ah, but with all due respect....
Ever wondered why really powerfull engines have mulitple exhausts? :wink: :lol:
cheers
8)
Eeyore
drum:
Anybody know how it effect a turbo diesel??
Presumably you want as little resistance as possible after the diesel??
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