Shifting with a Turbo

[jcp123]

A boost controller could help you stay out of boost when you don't want it and dial it back in if and when you want/need it.

[bhazard]

You can only dial down as low as your wastegate actuator is set up for. On my tbird, thats 10-12 psi. On the shadow its 4-5 psi and on my capri its around 7 psi.

An adjustable actuator would let you do as people are describing above, you could drop the actuator setting to allow no boost or less than the stock actuator is set up for and use a boost controller along with it for easier adjustment when you want it.

[robchalmers]

whirlygigs aren't always bad!

VW twin charger 1.4 (160hp version) produces less CO2 and more MPG on combined than the NA version!(80hp) As the name suggests not only does it have a Turobcharger its also got a supercharger. You can get a 122hp and 140hp version in the Golf, there is even going to be a 1.2l 105hp version in the Skoda yeti and I'm guessin new polo!

Dr Strangelove has been hard at work!!!

[RobertSmalls]

The 1.4L twincharged engine is the right idea, but I'd really like to see it in 0.7L format, with 60HP, in a Polo.

[Christ]

You can also give more leverage to the wastegate actuator, or put a prescribed-weight spring on the other side of the actuator that will net you whatever boost level you're happy with.

IOW - If you want 3 PSI max, and your wastegate won't open until like 10 PSI, get a 7lb spring and put it on the other side of the wastegate actuator arm. I don't actually think the math is quite that simple, but someone else suggested it, and I'm posting as a proxy.

[Ptero]

Christ is quite knowledgable about turbos but no one has touched on the basic problem: that is, any dealer-equipped model has too large a turbo for mpg applications.

I have over 2 million miles on properly-sized turbocharged engines. What are they on? Big trucks.

But those turbochargers are huge, you say.

No, they're not.

If you look at it in terms of power to weight, they are very small.

This is the Ecomodder Forum. Let's talk about ecomodding.

Any turbocharged engine has forged pistons and lower compression, if it has been properly assembled. All that is needed is to install a much smaller turbocharger with a properly adjusted waste gate and fuel delivery for excellent mpg gains. Your top end horsepower will fall off significantly but your midrange torque will delight you.

[pgfpro]

I love my turbo Del Sol.

My car never came from the factory turbo charged. I built my own turbo system.

As of right now my car gets over "10mpg city EPA" better then a stock
Del Sol, and closer to "15 mpg EPA" better freeway.

My BOV is open all the time until it sees boost. Then the valve closes.
So I never have any pre T/B positive pressure when the manifold is in vacuum.

At 5" hg or less you can here the BOV letting air out as Christ said. But on my engine it acts just like a N/A engine until you lay into it.

Now a adjustable BOV will only work with a speed density system. Mass Air systems won't like a open to atmosphere BOV.

[Dieselman]

Originally Posted by Christ

The idea with a turbo is that even when the manifold is under vacuum, the exact same circumstances (normally) without a turbo would put the manifold under higher vacuum.

The reason most people don't recognize this as boost is b/c the boost gauge is still in vacuum.

Originally Posted by Ptero

Any turbocharged engine has forged pistons and lower compression,

You are both thinking of petrol engines, whereas the O/p has a diesel so no intake vacuum (due to no throttle) and probably the same CR as a N/A diesel engine.

Ptero is correct about a smaller turbo creating greater boost at low revs but will ultimately restrict airflow at higher outputs.

I have found the best results for economy on a diesel without an instantanious on board fuel computer is to use an EGT gauge..high temps = high fuel usage.

This might be further improved with a boost gauge as well, as it may be better to run a higher gear under boost and higher EGT than to run in a lower gear.
It's really interesting seeing what affects the EGT, for example blocking the EGR valve made about a 50 degrees C reduction, lagging the exhaust manifold brought this back up again which improved turbo pressure and response.

[Palmer]

I'll ad that Any gas car that is turbo-ed, and is computer controlled, will ad extra fuel to keep the car from leaning out and blowing.

With diesels, you need to add boost according to your fuel input, and gas cars add fuel according to their boost. They seem to work on different concepts.

I've seen examples of turbo diesels consistently getting better mileage then N/A diesels. My mechanic dropped a 1.9L TDi from a 2001 golf into his 1990 jetta, added bigger injectors, a bigger turbo, and turned up the fuel pump. The car spews black smoke all over the place, is it pretty fast for a diesel, but he can still get over 50 mpgs on a car cruise that included a few little races on the highway with turbo-ed gas cars and vr6's (tdi won), and Got waaay better mileage then I did with my stock 2005 tdi-pd, driving normally.

My friend has a tdi beetle. He was happy with his mileage but decided to chip the car, and add bigger injectors to get better performance out of it. He doesn't care about mileage. However, By upping the boost and injectors, he now gets way better mileage, and a much faster car. The same guy also put a Tdi in a corrado and modified it for performance and power. He ended up with a car that can get over 700km to half a tank from normal to slightly aggressive driving.

Gas cars sorta get a lot worse mileage as you mod them for power. diesels, in the experience of seeing my friends mod their cars, get better.

[pgfpro]

Gas cars sorta get a lot worse mileage as you mod them for power.

Not all of them.

If you have a management system and have your turbo map correctly you should be able to improve your FE and crush your N/A performance by a mile.