Dumb Question Thread!

[Marky]

You might be onto something, hadn\'t thought of that

Full noise it\'s driving mint, it\'s only part throttle / low ish revs it does it - like that coming on boost sorta period - wonder if the tps has gone out of alignment at all, that could explain it

Not the end of the world by any stretch it just irritates the sh1t outta me is all

Might try spare ecu as well see if problem persists, problem is its intermittent enough it\'s a pain to make it do it and find if I\'ve sorted it or not. Need to get a obd reader thingy so I can look at what\'s going on

Problem for another day

[Shaun]

does a bigger turbo running the same amount of boost as a smaller turbo mean that there is more air going into the cylinder than the smaller turbo

[Andy_Mac]

Yes. Think of it like a river, a small river can be eroding the sides at the same rate as a much larger river but the larger river will flow alot more water. PSI is the basically the force the air creates on the things around it (the force that the river pushes on the sides). As a turbo gets bigger it can push a larger volume of air through (lb/min) while exerting the same force on other components.

This is just a basic rule of thumb though there are many other factors like piping that\'ll need to be accounted for to get more air into the cylinder, most modest increases shouldn\'t be a problem though.

Hope that makes sense, the concept used to do my head in a bit but it all makes sense now

[boon]

 Shaun said:

does a bigger turbo running the same amount of boost as a smaller turbo mean that there is more air going into the cylinder than the smaller turbo

Yes.

A tiny little compressor that runs off your ciggy plug can hit about 80psi but it flows tiny amounts of air.

Conversely you can think of something like a radiator fan as being an extremely low boost compressor that flows huge amounts of air.

A turbo is just somewhere on the scale in between.

[Guest]

Sure steves got a good post on his fb about it.

[gotasuby]

Actually if it\'s the same boost and temp then it will be the same amount of air and power. Will only get more power if exhaust turbine is more free flowing

But bigger turbos usually have the same pressure at lower temps compared to smaller turbos.

[Guest]

Off steves fb:

How often do you hear ( well atleast i do ) i wont more boost to make more power, well thats sort of true but not the real answer.

Boost doesnt have a lot of reflection on what your doing apart from bragging rights whats most important is the CFM that goes with it, comparing turbos is a different thing as much as some may know this for those who dont this is why your motor can go bang after a turbo upgraded.

For example your current turbo pushes 300cfm on 14psi the upgrade now supplies 550cfm for the same psi thus lies the issue that extra volume means extra fuel but can also offer cooler intake temps so that alone can mask over the effects of the extra boost.

Before turning up the wick get a retune done or atleast the mixtures checked with a high quality meter.

[gotasuby]

 evowrx said:

Off steves fb:

How often do you hear ( well atleast i do ) i wont more boost to make more power, well thats sort of true but not the real answer.

Boost doesnt have a lot of reflection on what your doing apart from bragging rights whats most important is the CFM that goes with it, comparing turbos is a different thing as much as some may know this for those who dont this is why your motor can go bang after a turbo upgraded.

For example your current turbo pushes 300cfm on 14psi the upgrade now supplies 550cfm for the same psi thus lies the issue that extra volume means extra fuel but can also offer cooler intake temps so that alone can mask over the effects of the extra boost.

Before turning up the wick get a retune done or atleast the mixtures checked with a high quality meter.

remember that a turbo may be able to supply 550cfm but you don\'t have to use it all. A flow chart of the turbo will tell you a lot about it

[Guest]

 gotasuby']

[quote name='evowrx said:

Off steves fb:

How often do you hear ( well atleast i do ) i wont more boost to make more power, well thats sort of true but not the real answer.

Boost doesnt have a lot of reflection on what your doing apart from bragging rights whats most important is the CFM that goes with it, comparing turbos is a different thing as much as some may know this for those who dont this is why your motor can go bang after a turbo upgraded.

For example your current turbo pushes 300cfm on 14psi the upgrade now supplies 550cfm for the same psi thus lies the issue that extra volume means extra fuel but can also offer cooler intake temps so that alone can mask over the effects of the extra boost.

Before turning up the wick get a retune done or atleast the mixtures checked with a high quality meter.

/quote] remember that a turbo may be able to supply 550cfm but you don\'t have to use it all. A flow chart of the turbo will tell you a lot about it

Yea I know what you mean. Doesnt tell me anything I have no idea how to read one.

[Shaun]

what i don\'t understand is that a cylinder has a displacement of 0.5 liter so how is it possible to force more air into the same size space without upping the pressure

[Koom]

 evowrx']

Off steves fb:

How often do you hear ( well atleast i do ) i wont more boost to make more power, well thats sort of true but not the real answer.

Boost doesnt have a lot of reflection on what your doing apart from bragging rights whats most important is the CFM that goes with it, comparing turbos is a different thing as much as some may know this for those who dont this is why your motor can go bang after a turbo upgraded.

For example your current turbo pushes 300cfm on 14psi the upgrade now supplies 550cfm for the same psi thus lies the issue that extra volume means extra fuel but can also offer cooler intake temps so that alone can mask over the effects of the extra boost.

Before turning up the wick get a retune done or atleast the mixtures checked with a high quality meter.

remember that a turbo may be able to supply 550cfm but you don\'t have to use it all. A flow chart of the turbo will tell you a lot about it

Yea I know what you mean. Doesnt tell me anything I have no idea how to read one.

Play around with this calculator

http://www.squirrelpf.com/turbocalc/

Good place to start getting your head around turbo compressor maps. Garrett have their Turbo 101, 102 and 103? pdf\'s floating around which also run through right from the absolute basics of turbo sizing.

[quote name='Shaun said:

what i don\'t understand is that a cylinder has a displacement of 0.5 liter so how is it possible to force more air into the same size space without upping the pressure

It starts with the fact that an cylinder doesn\'t often ingest 100% of its volume every revolution. Some engines can take in more than their volume per revolution (at a particular rpm band where everything comes together nicely) and other times you start loosing fresh intake air out the exhaust before the compression stroke. Or can\'t get rid of all the combustion leftovers before the intake stroke. Then you can change the density of the air that you are feeding the engine. Or change the length, volume, diameter of either the intake or the exhaust to move the sweet spot. Or change the cam timing so that it is more or less retarded to shift the torque curve. Or change the cam timing to change the overlap between the exhaust and the intake cams.

Basically if you change anything in this whole system, you can affect how much air (mass, not volume) can get into the cylinder on each revolution.

i.e. if the bigger turbo can raise the intake up to the same pressure as a smaller turbo, but it does it more efficiently so that the air doesn\'t get heated up as much, then it is more dense, so more mass of air gets into the cylinder. A decent intercooler can negate some of this. Then as gotasuby has mentioned about the turbine being more free flowing so the engine can exhaust the gases more efficiently. Its all a big balancing act and getting it all to come together at the right point to get the torque curve you want is the "black art".....

[Shaun]

 Koom said:

Basically if you change anything in this whole system, you can affect how much air (mass, not volume) can get into the cylinder on each revolution.

i.e. if the bigger turbo can raise the intake up to the same pressure as a smaller turbo, but it does it more efficiently so that the air doesn\'t get heated up as much, then it is more dense, so more mass of air gets into the cylinder.

thank you Koom

[madmike]

And just remember that when you read turbo flow/pressure maps that these can be up to 10% out..

The maps are constructed from a turbo built and tested at the factory. The turbos that come off the line can have very minute differences that cause changes in flow and pressure. So as with engines. Two turbos that come off the factory floor one after another may not perform exactly the same..

[BINKZ]

Does anybody know what size fitment tyres/mags you can fit on a V7 Wagon without having to roll the guards/utilise excessive camber?

At the moment i just have standard 17x7 prodrives with 215 tyres.

But i want to look at going to either 17x8 or 18x8 if possible with 225 tyres.

[Guest hate-evoz]

yeah 8" wide is easily able to go on v7

[johnny5]

 B-MAGIC said:

yeah 8" wide is easily able to go on v7

yup im on an * with a +44 offset

[BINKZ]

 johnny5']

[quote name='B-MAGIC said:

yeah 8" wide is easily able to go on v7

/quote]yup im on an * with a +44 offset

Isn\'t the wagons wheel arch smaller than sedans though? Hence my question.

[Guest hate-evoz]

 BINKZ']

[quote name='B-MAGIC said:

yeah 8" wide is easily able to go on v7

/quote]yup im on an * with a +44 offset

Isn\'t the wagons wheel arch smaller than sedans though? Hence my question.

yeah it\'ll fit easy man, no need for guard roll or lip roll, but what suspension are you running though?

[BINKZ]

Standard STi struts on pink springs

[gazzy2000]

can you use threebond supersealer on exhausts? i.e. down pipe to mid section

[lachlan]

ill give you one guess

[gazzy2000]

 lachlan said:

ill give you one guess

hey! this is the dumb question thread.. not the dumb answer thread

and as it turns out ppl do use that RTV on zausts

[Guest]

Yup people use crc silicon on it - no Im not one of them. My 550deg heatwrap disintegrated on headers no way in hell Id put silicon between any exhaust joint considering its rated to 330-360deg.

[tydon]

Putting a aftermarket bov on a Twinturbo bg5a legacy is a bad idea? and how?

[lachlan]

nah if you want one then just do it bro . assuming you want to vent it to atmosphere ?

make sure its shut when the car is idling . might not return to idle as smooth as factory .

its not actually going to damage anything etc