Turbocharging? Vacuum? Too much thinking. Smart people unite

[Wiegraf]

The difference there though ..again the turbo motor was 8.5:1 compression and the N/A was 9.7:1 ... therefore of course the n/a would get better gas mileage.... and not to mention gearing is different also between the two...

I have a hf trans and vx motor. No positive psi here... purely... cruising..at 65mph.. not racing, not top speed.. 65... mph.. cruising.

[ksa8907]

An apples to apples comparison is going to be nearly impossible to find. But look at this link, Compare Side-by-Side

At cruise, a car doesn't need much power at all compared to how much power it needs during acceleration, particularly if the vehicle can't feel underpowered. So what has to happen, and what we're finally seing automakers doing, is producing smaller displacement/high(er) boost engines. This combination produces power comparable to a larger displacement engine but much lower fuel consumption while cruising because the vehicle does not require the power.

If you want to turbocharge a vx engine you're going to increase fuel consumption. If you instead get an engine half its size and increase compression, add direct injection, add a turbo, properly tune it, and add a lower gear ratio top gear, you may very well improve efficiency.

[Wiegraf]

Merely aiming at efficiency... closer to 0 inHg on Turbo motor (without going positive) to increase intake temps (warm air intake) and increase VE SHOULD yield more though correct?.

[ksa8907]

Originally Posted by Wiegraf

Merely aiming at efficiency... closer to 0 inHg on Turbo motor (without going positive) to increase intake temps (warm air intake) and increase VE SHOULD yield more though correct?.

No, example, my cts cruises around 18"hg vacuum. Add a turbo and cruise at 0" hg vacuum? What do you suppose would happen to fuel consumption?

Lol, id be cruising at 150mph!!

Edit: if you want to reduce fuel consumption, you either need to reduce air intake(warm air intake) or increase the equivalence ratio(lean).

[freebeard]

Would not 'smart people' assemble, rather than unite?

[pete c]

Originally Posted by Wiegraf

Not 2X horsepower. Im talking purely cruising...not makinh power. At most 4psi. Nothing more. We will handle one subject at a time.

Maybe I'm missing something here, but as I said before, if 2 engines are the same displacement, the turbo one, if it is making boost is making a lot more power. If you back off the throttle and run it off boost, the NA motor will get better mileage, partly because of the drag of the turbo, but more so because it is a low compression engine.

[oldtamiyaphile]

Originally Posted by pete c

Maybe I'm missing something here, but as I said before, if 2 engines are the same displacement, the turbo one, if it is making boost is making a lot more power. If you back off the throttle and run it off boost, the NA motor will get better mileage, partly because of the drag of the turbo, but more so because it is a low compression engine.

Yes, but there's a middle ground. Running just barely any boost and staying out of enrichment.

At 50MPH my Fiat gets 70- 80MPG. My 2 ton van (diesel) gets 60+ MPG @45MPH.

So it's not all bad for turbos, but I'd say the amount of optimization that went into those engines is well beyond what a bolt on DIY kit would offer.

[Wiegraf]

Originally Posted by ksa8907

No, example, my cts cruises around 18"hg vacuum. Add a turbo and cruise at 0" hg vacuum? What do you suppose would happen to fuel consumption?

Lol, id be cruising at 150mph!!

You're thinking incorrectly...and maybe I am too...I'm just thinking a small turbo would "push" more air in rather then making engine suck.

[Wiegraf]

Originally Posted by pete c

Maybe I'm missing something here, but as I said before, if 2 engines are the same displacement, the turbo one, if it is making boost is making a lot more power. If you back off the throttle and run it off boost, the NA motor will get better mileage, partly because of the drag of the turbo, but more so because it is a low compression engine.

Like i said ... drag of turbo is like a muffler if anything.. so delete a catalytic converter (rear one) when you install turbo.. offset Mechanical efficiency.

And I'm never refering to POSITIVE PSI.....

Only vacuum....

Small turbo at 18 inHg vs N/A at same 18 inHg .. thought turbo would do better.

(I've adjusted my thinking now)

[ksa8907]

Turbos are ONLY used to increase power on gas engines.

By "pushing" more air into the engine the ecu will see a lean condition and increase fueling. Turbos are for reducing brake specific fuel consumption (more power per unit of fuel), not reducing fuel consumption.