unuseful turbo information
 

been researching turbos and found this uk site well worth a read heres just one section.

i didnt realise that fitting a large bore exhaust creates a problem trying to control boost!!!!

refer to section exhaust systems:
We have a particular component here which divides the tuning fraternity down the middle…some people believe a drain pipe exhaust system (3.5-4.5”) is the way to power nirvana, where as there is a camp that believes in a well made average size (2.5-3.0”) with flowing mandrel bends will be of more benefit…we tend to sit in that camp for a couple of reasons.
1.The engine/turbo combination on any vehicle was never designed to run with a 4” ‘drainpipe’ exhaust with one straight through box at the back.

2. These big exhausts often have very detrimental effect on the turbocharger, the turbo oil seal system is designed to run as a pressure differential seal and the lack of back pressure is one of the first reasons a turbocharger leaks oil (smokes at idle and on overrun). How many turbo cars do you see with 4” exhausts smoking at the traffic lights?
3.The other important fact is that the waste gate system (on integral waste gate units) are designed to have back pressure to equalise the gas pressure before & after the turbine…this differential can be so distorted by these exhausts that the waste gate can no longer control the boost which leads to boost spikes, boost creep and the worst effect can be over speed of the turbine rotor which will cause premature failure of the turbo.
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http://www.turbodynamics.co.uk/faq.htm
I have fitted your new hybrid turbo together with a new 3 inch exhaust and I cant stop the boost pressure rising? This is called "boost creep" quite often when fitting a new hybrid turbocharger and /or a new big bore exhaust system it has a detrimental effect on the balance of back pressure between the turbo and exhaust system, this in turn stops the wastegate from functioning as the gas pressure takes the easiest exit and bypasses the valve.

hahah if anything is proof that a bigger exhaust is better for power, it's boost creep.

the simple truth is that if your wastegate is too small, you will not be able to control boost adequately.

get a bigger wastegate.

This is the stupidest thing I have heard all day...you WANT a bigger exhaust, why do 800+ whp Supra guys run 4" or 5" exhaust?! Boost creep is caused by a wastegate not being able to flow the abundance of boost fast enough, solution=bigger wastegate!

instead of boost controllers we should all just run 1" exhausts for that epic 20psi of BOOZT

when you say bigger wastegate are you meaning stronger spring instead of using a 7psi spring use a 15psi spring tocontrol the boost better?

if not say i have a gt2860rs disco potato how do i fit a bigger wastegate and where from?or are you referring to fitting an external wastegate from that site it says if theres no backpressure the exhaust gas takes the easiest route down the exhaust avoiding the wastegate sounds like back pressure is needed no?
also whats the advantage of having an electronic boost controller over having just a wastegate set at 15psi?

They mean by bigger, the size of the opening in the valve. Like 38, 44, or 46 mm. You will pretty much need to go external on your turbo if you want bigger. Though I have seen people replace the flapper on a internal gate turbo with a larger one and port the opening to match.

think about how a turbo is powered, by exhaust.

if you have such a large exhaust and such low back-pressure that encourages flow through the turbine, how is a pea sized little hole that opens up going to flow enough gasses through the wastegate and bypass the turbine, slowing the turbo, lowering the boost?

3" exhaust is the reason I can't get rid of boost creep, but external wastegates setups arent cheap.

port the wastegate.

i already done did that

right i can understand in order to run an external wastegate i need a manifold that has that fitment for one.but how do i convert the standard turbo to run with an external wastegate?

buy a turbine housing that doesnt have a wastegate in it, or else buy about 5 minutes of time from a good metalworker/welder

If you know a good welder, you can have the internal flapper welded shut...

if i weld the flapper shut how do i control the boost?

if i buy a turbine housing without wastegate will it still have the same 5 holes to bolt up to a turbo elbow?

are you trolling?

your previous post was a question about how to run an external wastegate if you already had an internally gated turbo, then when we told you to weld the internal wastegate shut, and you asked how to control boost?....you have some more to learn.

There are a huge number of turbine housings that are designed to match the 5-bolt setup without a wastegate for the sole purpose of being able to swap your IWG housing out in order to run EWG without needing a new downpipe (though you will need to figure out how to get EWG gasses back into your downpipe.

ahhh sorry i follow now so i weld it shut then i can buy a manifold to which i can mount a tial ext w/g is that right?

or i can just run it without the gasses going back into the main exhaust pipe called a screamer i think.

This is a beautiful example of the reason why you don't believe every theory postulated in a forum. Every bit of it is rubbish.

please explain why it is rubbish

try reading all the previous posts on this thread, they already explain why it's bunkem.