what I was trying to say is that boost is basically excess air that is NOT consumed by the engine. If you make your engine breath better so that it can consume more air at redline then your boost at redline should go down assuming your already maxxed out on your wastegate duty cycle. Your goal should not be producing more boost, it should be producing more power and more boost does not always equal more power.

 

thanks guy i did the test a while back, already replaces the tbshaft seals and i can hold 27lbs in the system with basicly no leaks. when i say basicly no leaks if i check the pressure a couple minutes later its at like 25 so its not fast enough of a leak to really sacrifice any while making power.

 

this isnt entirely true. actual boost pressure is made on the opposite side of the exhaust stream. the less restriction you have on the intake/cold side the more boost you are capable of producing.

a restrictive hotside which is the exhaust will cause more backpressure which in turn will not allow your turbine to spool as freely to creat the boost pressure on the cold/intake side. iv always heard you want the exhaust as free flowing as you can on a turbocharged car. a difference in turbo design or its housings are the cause in loss of or addition to restriction on both sides.

some of what you are saying is deff true but in some instances does not agree with the simplicity of flow

thanks for the input

 

forgot to ask but ur setup holding 26psi, are u still internal wastegate or external. i kno this makes a big difference in some setups.

 

lol boost is anything above atmospheric pressure in the manifold. example..

if atmospheric pressure on earth at sea level is say around 14.7lbs and theres a car next to you there will be that much pressure in the intake manifold. so the turbo will actually have to make 15.7psi in the intake manifold to register 1lb of boost on a gauge. boost is air pressure on top of atmospheric pressure.

 

its a stock evo 8 turbo stock internal wastegate.

 

this makes sense i kno that 25psi is about max for making power anything there closer top redline or higher up in boost on the stock turbo would just be hot unusable air without a meth injection kit and im trying to stay away from those.

guess i should have worded that differently but im trying to hold 25 through my heaviest tq range i dont mind the taper up top as much

thanks for the info.

 

lol ya sure ur gauge isnt like 6lbs off lmao. no offence but the stock internal actuatore are weak and leak way before 26 psi unless ya ball peen'd it haha

 

if your setup is capable of flowing enough air to support useable boost till redline then why not?

the problem with runing boost up top is the efficiency range of the turbos. another aspect of this is that that the air gets too hot and not dense enough to really make useable power at those rpms.
buuut with an efficent way of cooling the air and being able to use it then running a specific number all the way to redline instead of a taper will make more power..

basicly this is just changing the tq curve from a specific range to a wider range that carries to redline.

your right with the more boost does not always equal more power but when your using boost to make power thaats what we want to accomplish

thanks for the input

 

my guage is 100% correct. 1.8 bar.=26psi. also showed on the computer i was being tuned on. its not wrong lol

 

[quote=sktng22;9841720]my guage is 100% correct. 1.8 bar.=26psi. also showed on the computer i was being tuned on. its not wrong lol[/quote

hmmm interesting. thats the first iv heard maybe its an viii thing

 

I have the opposite problem. My boost doesn't taper, currently 25psi, yet I get knock up top and my timing is already really low. I figure that having the boost taper would be better for my set up as I can get rid of the knock and maybe get some more timing. I have a Greddy Profec B Spec 2 with gain at it lowest setting which is 5%. How can I get my set up to taper, unwind the wastegate actuator?