Turbo Lag

[Merve85]

Anyone know how to reduces turbo lag?

[daktari]

Anyone know how to reduces turbo lag?

Keep it on boost. :yahoo:

[Jones~32]

Better flow of gas on intake and exhaust

ie. straight air intake pipe, decat & larger bore exhaust.

Although beware of boost creep :!Removed!:

[Jones~32]

Anyone know how to reduces turbo lag?

Keep it on boost.

Or what he said works too

[daktari]

Better flow of gas on intake and exhaust

ie. straight air intake pipe, decat & larger bore exhaust.

Although beware of boost creep :!Removed!:

As the sensible reply above suggests. Keep the exhaust dia below 2 1/2 inches unless you're running silly power.

[Sketchy]

Also a spot of !Removed! on the ignition map around the 0-5psi area can make a noticeable reduction in turbo lag, however this will require a mappable ecu and works better with hotter cams, so might as well rebuild the engine at the same time and get a bigger tubby...

And now you know why none of us have any money...

[rallymad]

Better flow of gas on intake and exhaust

ie. straight air intake pipe, decat & larger bore exhaust.

Although beware of boost creep :!Removed!:

Could someone explain to me what exactly is boost creep and how do i avoid it as im doing all of the above mods

Thanks Paul

[Sketchy]

Better flow of gas on intake and exhaust

ie. straight air intake pipe, decat & larger bore exhaust.

Although beware of boost creep :!Removed!:

Could someone explain to me what exactly is boost creep and how do i avoid it as im doing all of the above mods

Thanks Paul

OK let me know if I loose you at any point.

The stock CT20b toyota turbo controls it boost level by way of an internal wastegate, which once the require pressure has been achived redirects some the exhaust gases so that it by-passes the exhaust turbine thus maintaining the boost level at a steady level.

Due to the design of the twin scroll exhaust housing on these turbos, the wastegate path is particularly angled. At stock operating pressures and exhaust this isn't a problem because the back pressure in the system causes the speed of exhuast gas going through the turbo to be resonably slow which also causes your original problem of laggy response.

Now when you remove the Cat and exhaust and replace with nice free flowing items the back pressure in the system is reduced massively and the speed of the exhaust gases improves dramatically, this in turn allows the exhaust turbine to spin faster and produce boost more easily. The down side to this is that because of the angle and nasty path of the wastegate on the stock turbo, if you go to free on the exhaust then you get to a point where the wastegates flow ability is overcome. This basically means that the wastegate is unable to divert enough gas to limit the boost pressure.

When this happens you get uncontrollable boost rise i.e. you want to be running up to 17PSI but end up running 25PSI.

This is very different to boost spike which is when you get a brief rise in boost pressure which then settles back down to normal pressure. With boost creap depending upon the amount of creap the boost levels becomes completely uncontrollable and will end up putting holes in your engine...

[rallymad]

Better flow of gas on intake and exhaust

ie. straight air intake pipe, decat & larger bore exhaust.

Although beware of boost creep :!Removed!:

Could someone explain to me what exactly is boost creep and how do i avoid it as im doing all of the above mods

Thanks Paul

OK let me know if I loose you at any point.

The stock CT20b toyota turbo controls it boost level by way of an internal wastegate, which once the require pressure has been achived redirects some the exhaust gases so that it by-passes the exhaust turbine thus maintaining the boost level at a steady level.

Due to the design of the twin scroll exhaust housing on these turbos, the wastegate path is particularly angled. At stock operating pressures and exhaust this isn't a problem because the back pressure in the system causes the speed of exhuast gas going through the turbo to be resonably slow which also causes your original problem of laggy response.

Now when you remove the Cat and exhaust and replace with nice free flowing items the back pressure in the system is reduced massively and the speed of the exhaust gases improves dramatically, this in turn allows the exhaust turbine to spin faster and produce boost more easily. The down side to this is that because of the angle and nasty path of the wastegate on the stock turbo, if you go to free on the exhaust then you get to a point where the wastegates flow ability is overcome. This basically means that the wastegate is unable to divert enough gas to limit the boost pressure.

When this happens you get uncontrollable boost rise i.e. you want to be running up to 17PSI but end up running 25PSI.

This is very different to boost spike which is when you get a brief rise in boost pressure which then settles back down to normal pressure. With boost creap depending upon the amount of creap the boost levels becomes completely uncontrollable and will end up putting holes in your engine...

Thanks for the info now i dont know what to do is it safe to do the mod or not is there a way to keep an eye on this or better still stop it from happening . Is this garunted to happen i see you have the mod done do you find the boost going out of control on your 4??????

Also will the aussie decat connect straight to the stock exhaust as i have a apexi backbox and with the idea of holes in my engine im getting afraid would i get much powergain with just the decat and apexi backbox .

Sorry for all the questions. Thanks again Paul

[Sketchy]

Thanks for the info now i dont know what to do is it safe to do the mod or not is there a way to keep an eye on this or better still stop it from happening . Is this garunted to happen i see you have the mod done do you find the boost going out of control on your 4??????

Also will the aussie decat connect straight to the stock exhaust as i have a apexi backbox and with the idea of holes in my engine im getting afraid would i get much powergain with just the decat and apexi backbox .

Sorry for all the questions. Thanks again Paul

No worries Paul Questions are what the forum is here for.

Unfortuanately boost creep on the stock turbo is a bit hit and miss some cars get it some don't.

However the general consensus is keep a setion of the exhaust to 2.5" diameter and you'll be ok, I assume from you post that your keeping the stock flexi section? This will be fine and should keep everything in check, and the Assuie DP will mate up to this nicely.

In my case I've gone for the Aussie 3" DP and Aussie 3" flexi but with the Sports cat in it, this provides a bit of extra back pressure to the system and helps keep things in check nicely on my car. Also the Nur Spec is actually only 70mm bore which is about 2.7" not 3" like most people seem to think. However this setup was a bit of a gamble on my par as other have the same setup and still seem to get a bit of creep but mine holds nicely at 14PSI with the stock boost control system.

I wouldn't go for the 3" flexi in your case as the Apexi is a full 3" system and one of the ones known to cause creep problems. Keep the stock flexi in place and you should be fine, but also get a decent boost gauge if you haven't already so you can keep an eye on things properly.

[rallymad]

Thanks for the info now i dont know what to do is it safe to do the mod or not is there a way to keep an eye on this or better still stop it from happening . Is this garunted to happen i see you have the mod done do you find the boost going out of control on your 4??????

Also will the aussie decat connect straight to the stock exhaust as i have a apexi backbox and with the idea of holes in my engine im getting afraid would i get much powergain with just the decat and apexi backbox .

Sorry for all the questions. Thanks again Paul

No worries Paul Questions are what the forum is here for.

Unfortuanately boost creep on the stock turbo is a bit hit and miss some cars get it some don't.

However the general consensus is keep a setion of the exhaust to 2.5" diameter and you'll be ok, I assume from you post that your keeping the stock flexi section? This will be fine and should keep everything in check, and the Assuie DP will mate up to this nicely.

In my case I've gone for the Aussie 3" DP and Aussie 3" flexi but with the Sports cat in it, this provides a bit of extra back pressure to the system and helps keep things in check nicely on my car. Also the Nur Spec is actually only 70mm bore which is about 2.7" not 3" like most people seem to think. However this setup was a bit of a gamble on my par as other have the same setup and still seem to get a bit of creep but mine holds nicely at 14PSI with the stock boost control system.

I wouldn't go for the 3" flexi in your case as the Apexi is a full 3" system and one of the ones known to cause creep problems. Keep the stock flexi in place and you should be fine, but also get a decent boost gauge if you haven't already so you can keep an eye on things properly.

Thanks for all the advise you have cleared up all my questions ill get the decat and see how i go from there .I dont have a boost gauge but one is on the cards very soon. Thanks again Paul