Strangeness while saving gas
Posted: Fri May 18, 2007 10:27 am
I decided to do some testing on my gas usage. I flew into DC, picked up the car at night and started a long drive down south. I filled up with piss gas in Woodbridge and wanted to see how high I could get my mileage.
Driving very softly, drafting semis, high air pressure, and stiffest suspension settings without changing my injector scaling, I have gotten 350 miles and I think I van get 20-30 more off my tank. DC driving is going to kill the last part though.
So, now I'm getting to the weirdness.
I was driving back up from down south in the middle of the night. Never going into boost, and staying in high gears. I had come to a hill in Wilderness and was in 5th with revs down around 1500. I rolled on the gas 'till the needle was getting close to 0. At 1800 rpm, I noticed a strange noise, a big whooshing sound. The car started to shudder verry quickly. Just before I took my foot of the gas, I noticed that I had hit 8 pounds of boost. The water injection kicked in at 5 lbs, so I heard that noise and looked over at the boost guage and saw it climbing just before I layed off the gas.
Later that night after trying unsucessfully to duplicate the event (not enough steep hills where I could go slow on in 5th), I realised what had happened. I was in one of the strange load sites of the UTEC that nobody in their right mind would ever find themselves in (go figure, eh?).
My injectors were dumping gas at the low RPM. The rich mixture was getting into the headers and lighting off again. That was the noise I had heard. In effect, it was a turbo pre-spool as there is no way I should be seeing boost build at such a low load and RPM setting.
So, just thought I would share.
Go on with your lives now.
Driving very softly, drafting semis, high air pressure, and stiffest suspension settings without changing my injector scaling, I have gotten 350 miles and I think I van get 20-30 more off my tank. DC driving is going to kill the last part though.
So, now I'm getting to the weirdness.
I was driving back up from down south in the middle of the night. Never going into boost, and staying in high gears. I had come to a hill in Wilderness and was in 5th with revs down around 1500. I rolled on the gas 'till the needle was getting close to 0. At 1800 rpm, I noticed a strange noise, a big whooshing sound. The car started to shudder verry quickly. Just before I took my foot of the gas, I noticed that I had hit 8 pounds of boost. The water injection kicked in at 5 lbs, so I heard that noise and looked over at the boost guage and saw it climbing just before I layed off the gas.
Later that night after trying unsucessfully to duplicate the event (not enough steep hills where I could go slow on in 5th), I realised what had happened. I was in one of the strange load sites of the UTEC that nobody in their right mind would ever find themselves in (go figure, eh?).
My injectors were dumping gas at the low RPM. The rich mixture was getting into the headers and lighting off again. That was the noise I had heard. In effect, it was a turbo pre-spool as there is no way I should be seeing boost build at such a low load and RPM setting.
So, just thought I would share.
Go on with your lives now.
Pretty interesting, I have to admit! Seeing as how it was just load zones that you normally don't use.... you could tune for it