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Boost and power

Roy

By Roy,
in Engines & Forced Induction

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Sydneykid Grand Master

Sydneykid

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Ok...a few generalisations first...:D

You have two turbos both flowing 60cfm into the same engine. The inlet temps are the same but in order to supply the 60cfm one of the turbos has to run 20 psi vs the bigger turbos 14psi.

So which turbo will make more power?

Firstly let me say that I think that scenario is impossible. There is no way (that I know of) for a smaller turbo at 20 psi to supply 60cfm at the same temperature as a larger turbo does at 14 psi. In addition to turbo rpm differences, there would be some engine rpm differences (ie; the larger turbo is going to need more engine rpm to produce the same airflow). Since "power" (horsepower I assume) is torque X rpm / 5250, the different engine rpm would make a comparison difficult.

But let's say it is possible, I believe that the larger turtbo will produce more power because it has less exhaust restriction (via the larger turbine). If this (larger turbine) is the primary reason for the 14 psi versus 20 psi, then the extra power will be substantial.

:cheers:

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R32 GT-R Collaborator

R32 GT-R

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Just my thinking but wouldn't they have the same total power apart from the obvious lesser exhaust restriction as SK said, but the larger turbo spool up much later in the rev range and the smaller turbo spool up quicker therefore the smaller turbo would give the power quicker than the bigger one......does that make sense?

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Roy Grand Master

Roy

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you need a mrs troy

Stuff that, recent times have proven they are more trouble then the R32:)

Im curious to try a new turbo that is a bolt on to my setup. Basically im running about 17psi to make 235rwkws.

My current turbo flows about 42-45cfm. The turbo i want to run flows around 60cfm. Now here is the thing the turbo uses the exact same turbine as i currently run, the same exhaust housing, just has a bigger compressor and associated compressor housing.

The diameter of the wheel is 3mm, maybe it was 4mm bigger then what i currently run.

Could be interesting to see how it performs

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Sydneykid Grand Master

Sydneykid

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Stuff that, recent times have proven they are more trouble then the R32:)

Im curious to try a new turbo that is a bolt on to my setup. Basically im running about 17psi to make 235rwkws.

My current turbo flows about 42-45cfm.  The turbo i want to run flows around 60cfm. Now here is the thing the turbo uses the exact same turbine as i currently run, the same exhaust housing, just has a bigger compressor and associated compressor housing.

The diameter of the wheel is 3mm, maybe it was 4mm bigger then what i currently run.  

Could be interesting to see how it performs

My guess.......More airflow to make more power = more boost, as the turbine is going to be a restriction at the higher airflow. This usually means closer to compressor surge, as the compressor can deliver more flow than the turbine can receive. Usually Trust add larger turbines for more power, this avoids the compressor surge issue.

Should be an interesting experiment none the less.:cheers:

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R32 GT-R Collaborator

R32 GT-R

Posted
Posted
Stuff that, recent times have proven they are more trouble then the R32:)

Im curious to try a new turbo that is a bolt on to my setup. Basically im running about 17psi to make 235rwkws.

My current turbo flows about 42-45cfm.  The turbo i want to run flows around 60cfm. Now here is the thing the turbo uses the exact same turbine as i currently run, the same exhaust housing, just has a bigger compressor and associated compressor housing.

The diameter of the wheel is 3mm, maybe it was 4mm bigger then what i currently run.  

Could be interesting to see how it performs

If you run the same PSI (17) as you curently do won't it just make the same power more or less, just later it the rev range thus making the upgrade faily useless unless you run more boost?

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Roy Grand Master

Roy

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If you run the same PSI (17) as you curently do won't it just make the same power more or less, just later it the rev range thus making the upgrade faily useless unless you run more boost?

This is where i was looking for ppls feedback as the theory goes out the window i suspect in application.:P

If i run 17ps with a 2530, then 17psi with a 3037 then i would hope the 3037 would make more power:) Thing is what happens when you run the 3037 compressor and cover on the the 2530 turbine:confused:

You would think you get surge city. But the TD06 turbines flow a lot more then a 2530 turbine, and provided my exhaust valves and head etc are a restriciton before my Trust turbine/housing then i wonder if its possible that this setup may just do the job.

It will be interesting little experiment.:mad:

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