Porsche 996 Turbo

[andrew54]

I thought you all may be interested in what effects P&G may have for my car.

I have only started tracking fuel lately, but the effects of P&G are quite noticeable on the two tanks that I tried (50% of tank was regular driving so gains are not fully realized).

Combined EPA is 16MPG and with minor P&G and keeping my speeds in check I got 24MPG. Had I done this for an entire tank, I'm sure the results would certainly be more impressive.

[jedi_sol]

Nice work for a turbo car!

Plans on a kill switch?

[oldtamiyaphile]

Originally Posted by jedi_sol

Nice work for a turbo car!

Plans on a kill switch?

Kill switch + turbo = dead turbo, no?

[redneck]

.

The 911 would be my weekend car, not eco car...





>

[Sven7]

Originally Posted by redneck

.

The 911 would be my weekend car, not eco car...

Hey, you have to save fuel for the race track, right?

[jedi_sol]

Originally Posted by oldtamiyaphile

Kill switch + turbo = dead turbo, no?

Maybe, not necessarily. Depends on how the turbo is cooled.

On my sti, the turbo is water cooled, therefore, no need to let the turbo cool down. Even the owners manual says no need to allow the turbo to cool down before shutting off the car. Therefore, i interpret that as there is little risk in damaging the turbo with EOC cycles.

From other WRX STI forums:
The water gets into the turbo, cooling it down, evaporates from heat, that vapor goes into return line, new water gets into the turbo, cools it further, and the cycle continues even with the engine off. Just pulling into a parking spot will give your turbo all the cooling down it needs.


However, if none of this is correct, at least i've got a 60,000 warranty on my car

[serialk11r]

24 is pretty good considering that car is what, 8.something compression ratio?

EDIT: oh, 9.4. Still pretty crappy.

[oldtamiyaphile]

Originally Posted by jedi_sol

Maybe, not necessarily. Depends on how the turbo is cooled.

On my sti, the turbo is water cooled, therefore, no need to let the turbo cool down. Even the owners manual says no need to allow the turbo to cool down before shutting off the car. Therefore, i interpret that as there is little risk in damaging the turbo with EOC cycles.

From other WRX STI forums:
The water gets into the turbo, cooling it down, evaporates from heat, that vapor goes into return line, new water gets into the turbo, cools it further, and the cycle continues even with the engine off. Just pulling into a parking spot will give your turbo all the cooling down it needs.


However, if none of this is correct, at least i've got a 60,000 warranty on my car

I agree with the above, however, when you EOC, you run the turbo at high load/ boost and instantly turn it off. That's quite a bit different to the pulling into a car park scenario where you'll be driving for at least 30 seconds off boost. I don't think any OEM's are testing their turbos for EOC conditions.

Moreover, it's not only the cooling that's the issue, it's the potential for starving the turbo bearings of oil (turning the engine off while the bearings are still spinning.

[jedi_sol]

Originally Posted by oldtamiyaphile

I agree with the above, however, when you EOC, you run the turbo at high load/ boost and instantly turn it off. That's quite a bit different to the pulling into a car park scenario where you'll be driving for at least 30 seconds off boost. I don't think any OEM's are testing their turbos for EOC conditions.

Moreover, it's not only the cooling that's the issue, it's the potential for starving the turbo bearings of oil (turning the engine off while the bearings are still spinning.

Yes, very valid points.

After doing some research on other sti forums, it seems modern water cooled turbos and synthetic oil has virtually eliminated the "coking" issues. The general consensus is:

"Cooldown: Zero unless I was going full boost right before I stop. Then I will idle it 30seconds+
Our turbos are oil and water cooled and will continue to flow water through a clever convection mechanism with the engine off so long as the turbo remains warm. That, plus running synthetic oil virtually eliminates the coking problems old turbo cars had. Again, read the manual; the car does not need a cool down period."

With that in mind, if I romp on boost, of course I will not EOC right away. However 90% of the time, I am far from using boost during my daily commute. Also, before I push my kill switch, I let the car coast at idle for about 5 seconds, therefore it's not a "hard" the shut off.

So I guess it just depends on the kind of turbo you have.

[oldtamiyaphile]

My mechanic is still replacing modern turbos at low milages from cars that do a lot of city driving.

I certainly look forward to learning how your turbo fairs with EOC, but personally, I already spend far too much on maintenance. I'd love to do it as it's an easy way to big gains, although my daily is a 2ton van that isn't much fun without the PAS working, so it's kind of a mute point.