turbo engines: getting to speed

[99clipsgst]

Subies and most of your factory turbos come with a BOV not the best ones but they do have them. When it comes to the BOV the best setup is for you to have the BOV recirculate into the turbo. Turbo's need air to spool by keeping the air in the system it helps to keep the turbo spooling and that equals less load on it.

As for me my turbo is fully spooled at 3K RPMs and unless I'm in a hurry I shift before I hit any boost. That way the ECU stays out of the closed loop and isn't dumping extra gas in.

[stigler4profit]

I found the best way to keep the Mazdaspeed6 (AWD here too)from getting poor FE is letting my wife drive.

But seriously what she does is pretty much keep it out of full boost, our car will spool up quite quickly.. all speed6's were manuals, and she basically will grandmaw the car to speed, and shifting at low RPM.
Try that keep it from full spool and drive that Spec-b (great cars by the way) like a grand-maw, until you get to speed.

[Dust]

I might be the opposite of what everyone else says, but here is my take. My worst tank came from babying it. Yes, you will use more fuel if you hit boost, and you will use alot more fuel if you go WOT. I usually go about 50% or so up to speed. IF you have a scangauge, find out when you go to "dump fuel" mode, and avoid that. Also, it might be a good idea to look at water/meth injection as a secondary fuel. It will keep your gas usage lower, and you can tune much leaner with it. Set it to come on early, and you should reduce gas usage when part-throttle boosting it. I will be installing one on my turbo move 660cc. 14 psi, and it's a dog out of boost, and probably isn't very efficient out of boost either. A big exhaust, DP, TP, and other flow mods should help you, as well as something to keep your IC cool. hooked up a sprayer on my IC for the hot days to cool it down. Heat below and insulation above a heatsink isn't the best way to cool things.

[Vince-HX]

twinscroll

[99clipsgst]

Check out what this guy has done with his Turbo Laser.
How To Save Gas - DSM Forums

[ALS]

Stay out of boost. Do what ever it takes to keep the engine from making boost. More PSI in the intake manifold the more gasoline the computer is going to inject into the engine.
I've owned an 81 Volvo 242 Turbo, 86 744 Turbo, and I'm running a 87 745 Turbo (362K) as my daily driver. Turbo gasoline engines are not the best way to increase gas mileage.
Turbo's on Diesel's are great way to increase power and fuel economy.

[tasdrouille]

Originally Posted by ncs

Subarus(and most modern turbo gas engines) have bypass valves instead of blow-off valves. Replacing the BPV with a BOV on a subaru without changing the MAF locatoin results in wasted fuel between shift.

Blow Off Valve FAQ: Read if you are thinking of buying one! - NASIOC

Thanks for the precision!

[heh2k]

Turbos can be more efficient than NA gasoline engines because the compressed air can be intercooled, unlike piston compression. See miller and atkinson cycles.

I'm been driving in I mode, which I believe keeps it closed loop, even at with the pedal to the floor. I've gotten 28.5mpg in suburban driving. Moderate throttle and shifting at 2 krpm makes a big difference. I also have gotten better at choosing the right gear to downshift to, so that I can slow when coming to reds with the injectors off until just before complete stop.

[Vince-HX]

Originally Posted by heh2k

Turbos can be more efficient than NA gasoline engines because the compressed air can be intercooled, unlike piston compression. See miller and atkinson cycles.

The Miller cycle

[getnpsi]

Keeping it right at 0 or -1 is probably the best as most ecus really start dumping the fuel the second the MAP shows a positive. It's pretty agressive acceleration much more than most n/a's so you can coast a while. With the extra TQ we can shift quite early and not be bothered too much in driveability even with a 4 cylinder. Driving like that in a N/A 4 cylinder especially from the early 90s or earlier would shake it apart, and ping like crazy.