Is there a stock based turbo out there (red, green, dom2, bbx etc) that can hold 25 psi to 8,000 rpms? I've read a zillion post about these and it seems most of them have some sort of boost taper. I get the whole efficiency argument that they are blowing hot air so to avoid knocking you lower boost. I was wondering if there are any turbos that bolt to the stock based manifold & DP that are built to provide 25psi all the way to redline?

 

http://www.atpturbo.com/mm5/merchant...egory_Code=BCS

 

A red, BBX, dom2 and even a green will hold 25psi all the way to redline. Well the green might come up short,especially to 8k but you never know.

 

Pretty much all of them will. Bryan @GST has posted some plots with the Dom2 & BBX holding 28. He speculated that the BBX would hold 30.

 

I'm not so sure the Red, BBX, Dom II will. If the car has all the bolt-ons including exhaust manifold and cams, well, I know the Dom II won't as it has the same compressor wheel as the GT3076R, and that will not hold.

If the car does not have cams, they might...

 

Mine has PnP exhaust mani and cams, and I hold 27.5, so the Red will.

 

One last thing to consider: airflow at 25psi on turbo X does not equal airflow at 25psi of turbo Y.

Depending on how restrictive the turbine side is (housing or wheel) will dictate how much flow is going through.

So lets say turbo X can hold 25psi to redline flowing 55lbs/min (making up numbers here) with a 'restrictive' turbine side. You put on a better flowing turbine side and now it's doing 22psi@60lbs/min. Sure, it's not making 25psi anymore, but it's flowing 60lbs/min. Looking at constant speed line on a compressor map, the pressure ratio (boost) drops as airflow increases on the right side of the map.

 

I think people tend to forget that. i tried explaining this to people that when you install cams the same thing happens. You hold less boost but are flowing more air. Boost is restriction in all reality

 

Never thought of it like that...good post!

 

But if your pipes, intercooler, intake manifold are all the same wouldnt the turbine the that flows 60lb/min equate to more psi since the definition of psi is pounds per square inch? Because you are flowing more air through the same amount of space therefore more pounds per square inch.

I really want a bolt on turbo that can sustain good air charge temps and maintain efficiency all the way without having to lower boost to compensate for poor efficiency or hot air. If there is such a thing.

 

But the turbo itself is different, so no. Think of the turbo as being bigger in simplest terms.

I made 340whp on my red on wastegate pressure, almost what i made on my stocker at 31psi when i first hooked it up.

 

Guys, don't forget that the engine is a massive air pump. The more RPM you pull, the more air it sucks (or can intake). So at higher RPM, the pressure drops because the engine can take in more air.

Pressure is a measure of resistance. The more resistance there is the less air gets into the motor and the more pressure you can read. If you add a cam / bigger valves, you remove some resistance. Therefore you get less pressure, but more air flow. That is why you see guys like Hollywood watching the g/s (amount of air injested) more than anything else. He only raises his boost till the g/s stops increasing. On his FP Green and cams, I believe he runs 22 psi.

 

The sideline conversation here is both interesting and true but it wasn't what the OP asked.

 

Well, the answer to his question is SEARCH! lol There is a whole section here with dyno posts with boost curves. And Cobb has a dyno database that shows boost curves and lists their mods.

I don't remember every turbo's boost curve off the top of my head. It looks like most of the guys that have looked at this thread don't either.

But I will say that the stock turbo will hold 25 psi at 8000 rpm if you put a restrictor plate in front of the throttle body.

The problem here is that the more mods you do to the car, the less boost it needs and can hold. Hence our conversation. You wouldn't throw a turbo on that is that big without having a built motor. Reving to 8000 RPM is not advisable without rods and springs and probably cams.

 

Think more about volume of air moved and less about pressure.. there's your power