The amount of boost pressure increase can be substabtial, E.g. from ~18psi upto 24psi (from what I have read, correct me if I am wrong).
My questions:
(And sorry if I am being a pain in the @$& here)
1. How do these tuners know the safe upper limit to boost pressure on my engine? Why not 27psi?
2. How do they know the longterm impact to engine wear (including the turbo) at these increased pressures? How could they know? Do they test to failure? Have acess to factory test data?
3. Assuming these tunes are relatively safe to install, meaning there is some risk involved but it's not a "gernade motor", is VW intentionally de-tuning my engine from the factory?
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These are pretty valid questions and apply to all forms of motor vehicle modifications.
1. On a turbo car the psi added will dictate how much extra power and torque you will add. There is a restriction to this due to the limits of what kind of psi the turbo can produce before it starts building substantial heat where adding psi is no longer beneficial. At this stage you have to take into account the fuel quality available as the car might gain power but start detonating after a certain boost level. The timing can be altered to combat this to certain degree and a happy place needs to be found of timing vs boost vs octane available.
Thereafter the car needs to be tested under variable conditions. The standard ECU has a factor that controls boost vs intake temperatures vs ambient. You got to see the range of where this occurs so you can keep the tune within the limits of adaption but also not continuously adapting (this makes for a smoother driving tune). The perfect tune has no adaption in most conditions which means the preset settings is a happy place without requiring ECU correction as it would come from the factory. A example of this is a tune that continuously pulls timing. This means the timing is not set at optimum and requires corrections on a on going basis. You may find a position where the timing is also ok for winter conditions but find in summer it starts pulling again. So the tuner needs to set the happy place for both conditions potentially leaving power on the table knowingly. This may also be the case when a tune is set borderline for 91 but it would be happier using 93. The guys that I know that wholesale flash tunes generally find this happy place and pull it back 5%. The tunes may not break dyno records but it makes for a happy customer in the long run. This is the best choice in my opinion since they do not have to sit and market their products since other tuners are doing the reselling of their software.
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The MK7 GTI in my case has been slightly harder due to various theories of why the turbos are breaking. The flutter that is heard is not normal in my opinion and points to spool surge. Research of early tune adopters with tunes that start balls to the wall with maximum boost available i.e. 380 torque from the onset have not had their turbo's last. This from a pool of 4 tuners local to me and probably in the region of 25 cars. Hence in my case a solution was priority before even considering release of a product.
2.Once the above is all figured out and is to each tuners liking a decision may need to be made on what amount of power is safe for the car. The VAG group generally over engineers the car to a large extent. Past history has dictated that the bottom ends can generally take whatever the stock turbo can throw at them on a continuous basis starting from the MK4 GTI and up. In all the past cases its generally a bad tune that breaks the motor and not a good powerful one.
With the turbos having a weakness the thrust bearing gets worn first. Its easy to test this as you can remove the intake pipe and check for play. We have done this on a continuous basis over various cars. When cars are first released tuners are each others best friends. I am not talking about what occurs in the US but their European counterparts and other places in the world. Disasters are discussed and information is shared. Most have gone out and purchased test cars and have driven them balls to the wall and to the point of recklessness to motor.
3. The power your car makes has already been decided before design phase and is purely a figure the marketing guys come up with. They need to keep check on what the competition is doing, keep fuel consumption levels competitive, meet emission average goals across the brand and build it in such a way that maximises profitability for the group. They also need to keep into account the other models within the brand and make sure up the price range the car does not trespass performance wise making it a non value car.
Hope I could satisfy your questions to a degree.
No abnormal noises, hesitation or anything. The tuned GTI is how VW intended to make this car but couldn't due to insurance and emissions regulations in my opinion, so they had to turn it down some. The new EA888 gen 3 is a tuners dream, strong engine thats built well and has tons left in it for us to play with. Honestly, that's the main reason I bought this car lol.
