HP gains per p.s.i. turbo boost

[morpheus78]

I have a BRM 2.25 cat back exhaust system, and have been told that a 6 - 8 PSI boost is what my 2.25 diameter piping can handle. My question is... how much horsepower and torque gain will 6 - 8 PSI give me??

[Eastcoast Wildboy]

Thats hard to say...... I have a 3.5 diameter and there is no limit on what to hold.... I just think it is what u can hold on ur gaskets cause i highly doubt ull blow a hole through piping with pressure like that??

[Checkered-Member]

I have a BRM 2.25 cat back exhaust system, and have been told that a 6 - 8 PSI boost is what my 2.25 diameter piping can handle. My question is... how much horsepower and torque gain will 6 - 8 PSI give me??

if in good condition exhausts piping will hold pretty much any boost you will throw at it, the concern comes with when does the exhausts become restrictive, and you start choking the turbine…with force induction application, when it comes to exhausts size bigger is literally better, your 2.25 should be just fine.

Average gains on a stock KA24DEs range anywhere between 12-18 hp per psi

Allot depends on the condition of the motor, efficiency of the intercooler, turbine and compressor specs, fuel & ignition maps (aggressive vs. conservative), quality of tuning…ect ect ect

But to answer your question directly, that exhausts will be to small if you run something like 15+ psi then you start loosing power because it will be too restrictive, not that the welds will blow…

EDIT: “You lucky that 100 shot of naws didn't blow the welds on the intake” - F&F

ROFL

[Hijacker]

the diameter of piping determines how well the turbo will breath. a small diameter pipe will cause back pressure, slowing the spool up time of the turbo. If you open the pipe up, the exhaust gasses will flow more freely, allowing the turbo to do its job easier. There is a point where the piping can get too big. If you go too big, then the exhaust gasses lose velocity and move slower out of the pipe, causing more back pressure.

3" piping seems to be the norm for turbo cars. I'm currently running 2.5" piping and am running 14 psi on my turbo. All I'm scarificing is a bit of top end power in exchange for a bit of low end torque.

2.25" is small for a turbo. You can run a turbo on it well past 8 psi and be fine, but the turbo won't shine until it can breath easier.

You will not blow out gaskets on your exhaust system. Gas will always follow the path of least resistance, so why would it want to push through a gasket or a hard pipe instead of flowing out the tail pipe, or going back into an open exhaust valve?

[morpheus78]

Im looking into getting the Greddy Kits for the KA engine. I dont know if I should get the intercooler or not though. I see that at 8psi the 240 pulls 194hp and with an intercooler it pulls 216hp. What does the intercooler do?? Another thing is that my car is automatic. Will I hear the blow-off valve exhale between shifts on the automatic??

[Hijacker]

you will most certainly want an intercooler. As air compresses, it gets hot. The job of the IC is to bring the temperature of the intake charge back down. Colder air is more dense, and less prone to detonation.

I suggest you do some reading up on how turbos work. http://www.howstuffworks.com has an excellent article on turbos.

[navysnail]

and you only hear the bov when the throttle plate closes, if your car is an auto, you keep your foot on the gas so no, you will not hear it

[morpheus78]

and you only hear the bov when the throttle plate closes, if your car is an auto, you keep your foot on the gas so no, you will not hear it

So then do I even need a blow off valve for an automatic?? What does that part do??

[Hijacker]

When the throttle plate closes, it shuts off the air, but the compressor wheel is still chugging along and sending air down the intake tube. Since the plate is closed, pressure builds up in the intake tube. If this pressure were to reach the compressor wheel, it will cause it to vibrate, and all sorts of fun (bad) stuff can happen. Bent fins, damaged shaft or damaged bearings. This is called compressor surge. To stop compressor surge, a "purge" valve is included in the system so that when pressure builds up, it opens and allows the pressure to escape instead of backing up into the compressor wheel.

A diverter valve simply recirculates the air back into the intake stream before the turbo, but after the MAF. A BOV vents to the atmosphere. BOV is generally used for both a DV and an atmo BOV. A DV is most desirable for a MAF system, because if the air exits the system (ie, vented) the computer will still think the air is in the system somewhere, and go ahead sending the fuel to the cylinders. You run rich, and end up stalling out at red lights sometimes. With the air diverted back into the system, it will reach the cylinder eventually, mixing with the fuel the computer set aside for it.

All a BOV does is make a big loud "Fwoosh" sound as the air exits the system. You still get that sound with a DV if you use an open element filter, but it won't be as loud.

In short, ANY turbo system needs a BOV, auto or manual.

[morpheus78]

I dont see a DV or AV or BOV of any kind included with the greddy system?? Do the turbo kits include connections for the EGR?? Will a 240 with a turbo pass emissions inspection?? These are things I need to know before I drop the $4000.