Jump to content
SAU Community
  • Welcome to SAU Community

    Welcome to SAU Community, like most online communities you must register to view or post in our community, but don't worry this is a simple free process that requires minimal information for you to signup. Be apart of SAU Community by signing in or creating an account.

    • Start new topics and reply to others
    • Subscribe to topics and forums to get email updates
    • Get your own profile page, build reputation and make new friends
    • Send personal messages to other members.
    • See fewer ads!

    Consider joining our newsletter for the latest content updates

    Click here to register

after some turbo info


Recommended Posts

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.

Link to comment
Share on other sites

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

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Latest Posts

    • Haha likewise, take my shit box for a spin and maybe you'll end up wanting a R33 shit box again lol...  
    • @Jasoncauser looks like a tight technical track, and definitely fun! Let's hope I make it to that day 😎  
    • The springs just lets the valve bleed off pressure/oil and it bypasses the feed gallery and heads back to where the pickup feed is On the LS the oil gets the the bearings...eventually  This vid explains the OEM pump well IRT the pressure release valve and how the bypass works The oil pressure light coming on intamitantly could just be a sticky valve, but, why pull something apart and not put something better in  I believe the low oil pressure light comes on somewhere between 5-10 psi Well will stick a gauge in after the installation to see what difference it makes at hot idle and higher RPM, and by high RPM I mean 6300 RPM.....LOL
    • My bottom end was rebuilt... so I think it's standard? Or refreshed.. standard? I didn't do it - I bought it with a lot of receipts but it has new bearings, new pump and was re-assembled. Apparently I have the standard flow, standard pressure pump. I did notice the oil pressure for a LS at idle is quite low, but not critically bad, I am happy that it's at about 28psi now (that my gauges work/don't leak). I would have probably specced the high pressure one, but I'll admit my ignorance after making my other post, I don't see how the pressure spring changes things. Given the pressure is a resistance to flow... high flow should also = high pressure, and your oil pump specifications should be dictated by how the engine is built (hence the sincere thankyou video man)
    • my first time on the track, just after getting the 32. tyres were 3yr old NT01's, rotors were cactus, pads were street pads. You can see the vibrations when I hit the brakes lol. After this is when I put new BDA rotors, Hi Temp Brake fluid and Intima type 2 pads. Wow what a difference
  • Create New...