What exactly happens to engine when you tune it?

[WhiteGTI]

I was in a Peugeot 207 the other day (the sporty version with the same engine fitted as in the Mini Cooper S), and noticed that it had both a water AND oil temperature gauge on the dash! Very impressed! Particularly as the MINI doesn't have either - just a beep when the engine gets too hot! Silly idea if you ask me!

[ukdub]

I was always told only give it some welly when your oil temp matches your water temp.  This took about 10 minutes from start up on my vr6 golf at a steady 60 mph

[Peskarik]

Thanks guys! 
I always wait until the water is up to 90 plus some minutes, before I even go close to 3000Rpm. It was just on couple of occasions that I noticed that when not fully up to temp the engine sounds coarseR after remap than before it. 

Chungster, what you said I already know. What i want to know is how higher boost pressure is achieved exactly? The turbo rotates faster and compresses air more strongly? I want to know the mechanics of the process, you know.  :embarassed:

Thanks in advance!

[RedRobin]

What i want to know is how higher boost pressure is achieved exactly? The turbo rotates faster and compresses air more strongly? I want to know the mechanics of the process, you know.  :embarassed:

Thanks in advance!

....Isn't it the ECU issuing instructions according to request and all dependent on how the ECU software is programmed?

[topher]

yes, there are various ECU controlled valves/solenoids that control the actuator/wastegate etc, to tell the turbo just how pressurised the system can be before it bleeds it out. Obviously that means a need to increase the fuelling, and the timing to suit the detonation.
All this is done with changes to dozens of tables in the ECU.
The resident experts over in our remap section of the forum can explain in more detail if its something of interest.

[Teutonic_Tamer]

Know almost nothing about cars.  :embarassed:
Never too late to educate myself, though.

Question 1: What exactly happens when E.30 engine is tuned to 300bhp (just the map). I know words like "boost", but in layman term, what does tuning mean? Turbo rotates faster or something?  :embarassed:

In very basic terms, you are basically improving the overall efficiency of the engine.  The latent or stored energy in the fuel is used more "fully", which creates more heat in the combustion chambers, which then creates more pressure in the combustion chambers, therefore applying a greater force on the piston.

In specific terms, this can be achieved in a large variety of ways.  Specifically regarding turbos, they wont actually spin notably any faster, but the higher boost comes from altering the pressure at which the "pressure release" valve opens.

Question 2: When I drive and the engine is not fully warmed up yet (water is not up to 90 degrees), if I go above 3000rpm (in 2nd and 3rd gears) the engine sounds very coarse. I started noticing it after the map. WHen it warms up, it is OK again. Anyone noticed? What could it be?

Eeeekk.  That is very bad news for an engine.    When the coolant temp is below its normal operating temperature, you should never exceed 3,000rpm, in any gear.  And you should never use more than half throttle either.  OK, if you have just pulled out of a blind junction, and you instantly notice a BFO truck belting rapidy up your chuff, then naturally give it some beans until a "safe situation" has resumed. 

As Chungster reports in an earler reply, the crucial issue is actually the oil temp, and because the oil is "thicker" than water, it takes longer to heat up.  However, being as the oil sump holds roughly half the volume as the engine coolant, the oil should roughly mirror the coolant.  As a general rule of thumb, in the Golf, I will wait about another minute or two in the summer, and slightly longer in the winter, from when the coolant gauge hits the normal.  On my RS4, though, it takes much longer, being as the sump holds a full 10 litres of Castrols finest - which explains why it has a readout of the oil temp.

[Teutonic_Tamer]

Question 1.

Remaps on turbo charged car mainly results in increased boost pressure and fuelling.

Only the "lesser" tuners just alter the boost and fueling.  The more reputable tuners can alter a whole host of other variables, with at least 30 different parameters to play with on the MED9.

[Teutonic_Tamer]

Just to add a little to number 1. More power comes from more pressure, but a side effect of this is more generated heat. That is why I had the intercooler to help keep things in check.

No it doesn't.  More power comes from more air volume, but the increased pressure simply improves the volumetric efficiency of the engine in general, hence increasing the power.

You are right about higher boost pressures generating more heat - but specifically this heat is generated in the inlet tract, before the combustion chambers.  Raising the heat of the air before the combustion chambers is bad, because as the temperature rises, gasses (and air in general) expand, and therefore for the same given volume as a lower temperature, there are less molecules (particularly the important ones, oxygen) in hotter air. 

[Teutonic_Tamer]

many people watch the water temp gauge to get to 90 degrees before giving it some welly.
however, what u REALLY want to see (and u can't unless u have another gauge) is the oil temperature.

water heats up faster than oil does. so even when the water temp gauge hits 90 degrees, oil temp may not be.  oil helps all the metal bits move efficiently with minimal friction. oil also goes to the turbine shaft on the turbo....and giving it some welly and running full boost when oil hasn't warmed up can reduce the life of the turbo significantly.

....And in the absence of an oil gauge and having waited for the water gauge to display 90, about how much extra time would you suggest we allow for the oil tto be likely to be warm enough?

Good question, and it comes with a "variable" answer. 

In the summer time, from a "cold start" (ie first start of the day in the morning), then maybe 1 to 2 minutes after.  On a chilly icy winters day, then maybe upto 5 minutes.

However, there is a flip side.  Say your car has already been used and reached normal temps, and the car has now been parked for an hour - then no delay at all after the coolant reaches normal.  Whilst a given volume of oil may take longer heat up compared to the same volume of water/coolant, it also cools down slower that water too.  Add to that the oil is stored inside the engine sump, nicely tucked away inside the engine compartment, for the coolant, a significant volume will be in the radiator, and will cool much, much quicker.  So you may find that when you turn on your ignition, but before starting the engine, the coolant guage will rise to a certain point (which will also roughly indicate your oil temp  ), as soon as the engine fires up, and starts circulating the coolant, then the cold coolant in the rad will be mixed with the coolant in the engine block, and the temperature guage will actually fall. 

[R32UK]

I dont usually wait for mine to warm up at all... well maybe a few seconds driving at the most. Is it still the same waiting time for non turbo cars??

The good thing is after a spirited drive home and parking in the bat cave.. the garage is usually nice and warm still in the morning thanks to the heat the engine generates. So maybe its not so cold in the mornings anyway??? or am I just being a hopefool???