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after some turbo info

JiVE

By JiVE,
in Engines & Forced Induction

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JiVE Rising Star

JiVE

Posted
Posted

Has anyone got a website handy that explains all about, Timers, BOV, FMIC etc.

I'm new to Skylines and turbo..... and well we all gotta learn sometime.

Normally i'd search for an answer to this question no doubt its been asked before, but have you ever tried to search for 'turbo' on this forum you get like 3000 results, heh.

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Steve Grand Master

Steve

Posted
Posted

Hmm, well I dont know about any websites. Have you tried a search engine, like google?

I can try and help a bit here if you like, as I know the frustration at typing common words.

Turbo timers - delays the engine switching off after you turn off the ignition. This is to allow the turbo to cool down. If it doesnt cool properly, the heat in the turbo can cook the oil in it, this is sometimes reffered to as 'coking'. the oil being coked on the inside of the turbo catridge can cause it to seize, thus the turbo will cease to work and need rebuilding.

the cartridge is where the bearings are between the compressor (inlet side) and turbine (exhaust side), and has a shaft through it mounted on bearings that allows the turbo to spin

Two main types of turbo timer, manual, where you set how long the car should idle for, or automatic, where the timer calculates how long to keep the engine running. Usually an auto timer will allow manual operation as well if desired.

BOV - when a turbo is making boost (positive pressure, so the air is compressed) and you take your foot off the throttle, the compressed air cannot move into the plenum (the plenum is after the throttle body, and distributes the air via 'runners' to the cylinders). A BOV will allow that air to be returned infront of the turbo or to atmosphere.

Without a BOV, the compressed air will revert back through the compressor, causing it to slow very quickly. This can cause alot of stress on the turbo, as they can spin at well over 100,000rpm. Another down side is that it takes time for a turbo to spool up again after being slowed, so it may induce what is called lag, where the exhaust gasses will take a moment to bring the turbo back up to speed.

Older cars didnt have BOVs, but nowadays all turbo cars (that I know of) in production have them for longevity, and for the sake of reducing lag.

FMIC - front mount intercoolers allow better cooling of the charge air (the air out of the turbo). It is like a big radiator to cool the air before it goes into the engine. Most stock intercoolers are very poor in design, and will not remove much heat from the charge air. You need to understand that when air is compressed it heats up. this is done firstly at the turbo, secondly when the piston compresses the air fuel mix as it moves upwards - two lots of heating compared to a NA engine only heating the air once.

Two big benefits from cooling the charge air.

- Firstly, the warmer the air, the more prone it is to detonation. Detonation is the spontaneous ignition of the fuel air mix in the cylinder, before the flame front started by the spark plug sparking. Fuel and air, when mixed, if heated enough will spontaneously combust - it is a violent explosion, compared to a controlled burn caused by the spark plug - it has the potential to smash pistons and hammer bearings). It is absolutely of the highest importance to prevent detonation. It is also called pinging or knocking.

- Secondly, the cooler the air, the denser it is, the more Oxygen, which means the fuel can burn better. this produces more power - just like when you drive your car on a cool morning compared with a hot afternoon.

Possible downsides to an intercooler is that if it is too big for the application, it may increase the time taken to build boost pressure, as the larger the area that the compressed air must fill, the longer it takes to fill. Just about any intercooler is going to be better than the stock ones on a GTSt, the GTRs however get very good intercoolers for applications up to around 300kw.

A poorly designed intercooler can be a waste of money too, as alot of science goes into designing a cooler to cool well whilst not causing a large pressure drop at higher boost levels - pressure drops can be caused by poor flow characteristics, such as the stock GTSt cooler:)

well theres some beginnings, I am sure you will only have more questions now, so fire away:) and welcome to the world of turbo cars and SAU

Abo Bob Grand Master

Abo Bob

Posted
Posted

I suggest you just trawl through all the posts here. Stick more to the forced induction performance section.

You'll see links to other websites along the way; go there! There's no easy answer. If there was you wouldn't remember it anyway. Repetition works Jive. Repetition works Jive. Repetition works Jive. Repetition works Jive.

Happy surfing.

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