Festy dyno vid 302 hp

[bhazard]

Doesn't Euro run the SVO turbo?
I think it's one step under a "super 60".

[Advancedynamix]

Doesn't Euro run the SVO turbo?
I think it's one step under a "super 60".

Like a "Great Job 60" ?

[bhearts]

Do you suspect euros turbo was at the top of it's power range with its setup?

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[Advancedynamix]

Do you suspect euros turbo was at the top of it's power range with its setup?

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No, he mounted it on the bottom of his power range, way out back there by the spare tire.

[bhearts]

I just always figured someone would have to push 25psi to break 300hp.

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[bhazard]

Its CFM that makes power, not PSI.

[Flyin4stroke]

His hot side is a .63 my old turbo was a .48. He says his turbo is good for about 350.

[bhearts]

Its CFM that makes power, not PSI.

I beg to differ. Cfm is the result of psi. They are proportionate to each other

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[Damkid]

I beg to differ. Cfm is the result of psi. They are proportionate to each other

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Based on how well the engine flows air through it

[bhearts]

Cfm is like the current, while psi is like the voltage.

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[sketchman]

^Exactly actually. lol

Just think about what psi comes from. It's more air pressed into a smaller space that creates pressure.

[Advancedynamix]

The turbine cherictaristics are just as important as the compressor for making power. It's s balancing act. Also with a centrifugal compressor the air speed is what creates the boost pressure, so the cfm generates the psi, but the volume of air that moves through the engine may be very different from one turbo to the next. Case in point, 16psi at 5500 rpm with a vj14 will be drastically different than 16psi at 5500 rpm with a gt2871r. That will be approximately a 100hp difference with a bp engine even though both are running at 16psi of boost pressure. The gt2871r turbine is less restrictive and more efficient, as well as having a better flowing wastegate. Boost pressure only tells a very small part of the very detailed story.

[ZephTheChef]

Cfm is like the current, while psi is like the voltage.

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You can always count on Bryan to use an obscure electronics analogy that will muddy the waters even more for everyone who doesn't have a EE degree.

Horsepower is about air mass into the cylinder, minus pumping losses, minus parasitic or drivetrain losses. Or more accurately, average torque is...and horsepower is a factor of torque and rpm. CFM is meaningless without the context of temperature and pressure, because it is a volumetric expression, not based on mass. You need the air density with the CFM to determine power output. This is why lb/min is a more accurate representation than CFM. The boost pressure is a representation of how restrictive the engine is compared to the compressor...ported heads/cam work will lower the boost pressure required to make a certain power because a higher air volume will be able to flow through the head. Engines that don't flow as well, will require higher manifold pressure to get the same overall air mass into the cylinder. You can shove a lot more air through the same sized orifice if you increase the pressure and therefore resulting density (assuming you are keeping temperatures under control)...this is what boost pressure is. If you had an engine that flowed more than the turbo compressor did, boost would not exist.

I think what Charlie is talking about is primarily the effect turbine sizing has on backpressure, and thus pumping losses...it also governs spool characteristics and all sorts of fun stuff. I assume you meant to say the MASS of air that moves through an engine may be very different from one turbo to the next, not the volume. The volumetric efficiency of a given engine is going to be the same at X pressure, but the air mass will change based on temperature and resulting density, and power/torque output will change based on the efficiency of the turbine and how much of a restriction it poses.

[ZephTheChef]

On second thought, the volumetric efficiency as a whole could certainly be changed by exhaust backpressure if you had significant overlap, and the residual exhaust in the chamber would reduce it somewhat as well even without overlap. So I take it back, Charlie is still correct with the terminology, I just misunderstood the direction he was going with it.

[Advancedynamix]

Yes, I meant Volume. As a simple way to explain how the volumetric efficiency of a turbocharged engine is only truly understood when the entire system is looked at as a whole, rather than hyper focusing on one component (i.e. head flow rate or compressor map.)
All too often the emphasis is placed on getting air mass into a turbocharged engine, but little consideration is placed on the exit strategy.
The O.P. was discussing the difference in turbine housings and wheels (the volume of the turbine housing in particular ) when all this discussion of CFM vs. PSI broke out. Mike is on the right track with where he's going.