Boost????

ok what do i need to knwo about boost? what is boost? and do i need a boost gauge if i have a turbocharged inline 4?  

I'm no expert, but what I do understand about a turbo charger is as follows:  

A turbo-charger uses exhaust from your engine to drive a turbine which compresses air back into your intake manifold.  If you've got the stock charger on your 4 cylinder it's probably small... producing maybe 10-15 pounds of pressure.  There really isn't a need to monitor your boost other than to show off the fact that it's there... not unless you're tuning the system and need to monitor the effects of any changes, or to assure any on-board boost controller is functioning properly if you have one.  

Again, I'm no expert, but I hope that gave you a better understanding about the nature of boost.  

Boost is pretty much the amount of compressed air from the turbo/supercharger, that's essentially being crammed into your engine. More air = more power, as long as there's enough fuel.

Do you need a boost gauge? Not really if you're stock, but if you plan on upping your boost, ie boost controller, tuning, performance parts, etc, then you will def. need it in order to watch for overboost.  
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what happens if i don't watch for overboost? and exactly how much modding before i need one?  

Well if you overboost, meaning too much PSI (too much pressure) for your engine to handle, then you'll have a nice blown engine.

I would get a boost gauge as soon as you start modding your car. You'll never know if your car will experience "creeping" (I think that's the term where boost will slowing start building up past the safe PSI limit).  
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ok thanks for all your help  

yeah, this helped me also. I see bost being used alot less then turbo, so that cleared it up. but also joe, you need to find out how much psi your pistons can take (just adding that real quick).  

woody_butler:
yeah, this helped me also. I see bost being used alot less then turbo, so that cleared it up. but also joe, you need to find out how much psi your pistons can take (just adding that real quick).

Boost is what you get from a turbo. (clearing this up, assuming I read your post right)  
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1994 GTO Twin Turbo
nothin wrong with front-wheel drive, I just refuse to own one

"yeah, this helped me also. I see bost being used alot less then turbo, so that cleared it up. but also joe, you need to find out how much psi your pistons can take (just adding that real quick)."

It's not a matter of how much boost the pistons can take, it's how much boost can you safely run on your stock fuel system.

Boosting is EXTREMELY complicated.  There are many things you need to be aware of when owing a boosted car.  Here's my quick write up on this subject.

Basically, boosting is charging an engine with air that's more than atmospheric pressure.  All internal combustion engines require the perfect mixture of air [oxygen] and fuel. Stoichiometric mixture at combustion is 14.7 parts of air to one part of fuel. aka 14.7 to 1.  That's the 'perfect' air to fuel ratio.  So, when you cram all that air into the cylinders when boosting, you're creating a lot of "parts" of air.  So in order to maintain the perfect ratio, more fuel is needed.  Now if you just slap on a bigger turbo that creates more pressure onto your motor with a stock fuel system, you won't be able to run any higher boost than what you did with your factory turbo.  When the turbo creates more boost than the fuel system can handle is called overboosting, and it can be a very scary thing.  For example, if you overboosted, the air to fuel ratio would go lean.  Lean meaning there is too much air. [as opposed to 'rich' meaning too much fuel]  A rich mixture is not threatening.  The air will mix with as much fuel as it can and it will be burnt.  The excess, unburnt fuel will just get pushed out the exhaust.  A lean mix, however, is not so nice to you.  If there's more air than fuel, the mixture will ignite prematurely before Top Dead Center before the spark can light it.  This happens because of compression temperatures.  Fuel is very picky about what temperature it ignites at.  The more fuel there is [the thicker it is] the hotter temp required to light it.  The less fuel, the colder.  So if you have too much air and too less fuel, the fuel ignites because of the heat generated by compression and creates a 'knock' This can bend rods, break rods, spin bearings, and destroy crank journals, pistons and even cylinders.  

There, I got tired of typing so I'll just end it.  Hope it helps.  BTW what do you drive, anyway?

And yes Jimi, creeping is when actual boost goes above anticipated levels.  This is mostly due to one thing, Restrictive exhaust. i.e. a faulty wastgate or a wastgate actuator that doesn't open as far as it should.  So, naturally if the wastgate doesn't fully operate, the exhaust get's blown past the turbine and not around it creating more boost than you set it at...  
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"It's either a fuel injection or carbeuration problem" said the man with a 2001 Saturn Ion
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Daily: 2000 Honda Accord Coupe F23A1 VTEC
Project: 1995 Eagle Talon TSi AWD