Quote:
Originally Posted by aerohead
In a past Cycle World Magazine article,a 'SMART' exhaust system was discussed for bikes.
The engines were operated on a dyno test cell and every conceivable transient engine load was analyzed.
Exhaust back pressure was altered throughout testing and a 'map' was developed for performance.
A 'valve-by-wire' (if you will) computerized system was developed in which closed-loop logic modulated a valve within the exhaust pipe ahead of the muffler,to always keep back-pressure in its sweet spot.
Back pressure is mandatory for low speed engine performance.Factory systems are 'tuned',and an alteration to the exhaust should be accompanied by an alteration to the induction.
I've run a couple of vehicles at Bonneville with bone stock powerplants and they do just fine at sustained WOT operation.And they get great mpg.Quiet too!
My opinion would be to leave everything under the hood alone until you've reduced your road load to a minimum with aero and rolling resistance.This is where your real savings are hiding.
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Interesting! Now hearing this coming from you guys I'm going to lean away from making her loud, if it affects the low end of the spectrum that much it will hurt my MPG goals. Still, I think I am going to replace the header... but leave the exhaust stock from the 2nd cat and back.
Will post a proper thread of it later, but basically my goal is to get my truck to be close to the same efficiency as my Honda Accord. It's apparently impossible I've learned as an SUV's shape is the biggest problem... now I just want to modify the engine to be as efficient as humanely possible. I was going to get a V8 Land Rover but instead opted for the 4 cylinder Suzuki Vitara 5spd, surely I would get better mileage. Nope, got about 19 MPG. worse than a land rover. Now after putting about $3500 in repairs on my Suzuki I can achieve 28 MPG, now for the very first time I get to plan an upgrade that ISN'T a repair, and I'm thinking exhaust. There has to be improvement to be made.
I will still get the header but on your stern recommendations I'm going to leave the rest of the exhaust stock! It is appreciated.