This is like if you drive like a granny you'd get up to 60mpg on the highway if you drive it like you stole your own car you would get 38 to 40, do the math, do you like to stump your car and go like a missle of course you'd take a hit, why do we bump up our cars to get better mpgs? No, we knew all along about this.
Fact is do you drive for mpgs or do you drive it and punch on the pedal all the time, for me I want both, I get it accomplished by 2 different ways,1) ECU with switchable programs where 1 will give me the most and the other restrict the limit on my car,,,, 2) drive it like a granny and I get 46 to 48 mpgs, so even leaving the ecu at ultimate setting i will accomplish the 46 to 48.
No idea if this setup is like what I have on my '06 but the little hose to the turbo is off and plugged for other reasons and I average 55 mpg overallSo now the duty is about 30-45% while cruising so the vanes are open about 70% assuming it's linear. Cruising down the road I'm making about 1-2 psi of boost where before it was 6-10 psi. And based in the last trips the boost map paid off in dividends.
Changing the vnt to be less restrictive brought me up to 44-46 mpg. By changing just the boost basically I was able to gain atleast 10% more fuel economy. No driving changes at all.
Hi,iirc even with the vanes wide open at 70mph cruise mine was showing 8 psi exhaust manifold pressure with the stock turbo, that was with like 1-2 psi boost
the stock turbo in general is just terrible for fuel economy, it's like they sized it to be efficient if you're driving 50mph with a 1.0l motor
go to something like a td04hl15t-5cm from a junkyard saab 2.3hpt and you'll notice a significant increase in fuel economy and power
ETA: I've done the 55 in a 70 thing, mostly while towing really stupid overloaded trailers with decades old tires and no spares to speak of.
It's downright dangerous holding up traffic like that. Sure, you save some fuel but at the cost of getting rearended from time to time? No thanks. I'll stick with a couple mph less than traffic (so like 74 indicated), then I've only gotta pass maybe 2 people on my 70mi commute.