Compound boost.

[Jaden]

Originally Posted by FRS Justin

So if I understand you correctly, you are saying the only way to reach mechanical efficiency of the engine at low rpm is to compound charge it? And that is the only reason to compound it is low end performance...


Not trying to be a ass just want to understand what your saying...

You can change the valve timing increasing lift or duration to increase engine flow at lower rpms also, or use a bigger less restrictive exhaust, but the easiest way is to increase the effective displacement by increasing boost earlier in the rpm range.


If you do that by getting a smaller, quicker spooling FI system, then you don't have the same airflow from the FI system.


By using compound boost, you can increase the effective displacement by using a quicker spooling turbo or pos. disp. s/c behind a bigger turbo to up the boost and increase the effective displacement allowing the engine to swallow more air and by doing so you aren't decreasing the FI airflow by using a smaller quicker spooling turbo as the source of FI airflow.


That's because in a compound boost system, you cannot have any more airflow than your primary FI system, the one that takes air from the atmosphere, provides.


Jaden

oh and yes, in a gas powered low displacement engine, that is the ONLY reason to compound charge it. In diesels that can take more total boost than a single turbo can efficiently provide, it's to increase the boost beyond the capability of a single turbo.

p.s. one other thing to keep in mind with high boost FI is that because the charge is flowing faster, retrictions like exhaust and valve timing typically have to be reduced/changed along with boost increases because they become greater restrictions the faster the flow through the engine is.


That's why you won't always see a truly linear increase with boost increases even if you are providing more airflow with higher boost. If conjunctive restrictions are greater, then you will see greater gains and if they are less or you don't also change the restrictions, you'll see lesser gains than the boost will dictate.


It becomes VERY complex which is why a lot of people get confused by the actual results.

[cdrazic93]

oh sweet jesus, lots of juicy ban material I hope. This is great! very entertaining

[Jaden]

Originally Posted by cdrazic93

oh sweet jesus, lots of juicy ban material I hope. This is great! very entertaining

And if you have half a brain, you'll actually learn some things too.


Jaden

[KR-S]

Honestly Jaden, if you're that confident both in your abilities and your theories that it works, then instead of insulting half the subforum, why not actually make it happen and prove that it really does work? I'm not sure what you expect to gain by continuing to argue with others.

To be honest, I was more interested in your plan to swap an Ecoboost V6 into your FR-S than I am with this project.

[weederr33]

I want to see a Rav4 V6 swap in our cars. That would be cool.





Then twin-charge it

[KR-S]

Originally Posted by weederr33

I want to see a Rav4 V6 swap in our cars. That would be cool.





Then twin-charge it

I want to see the following:

- Lamborghini V12 swap
- Audi/Lamborghini 5.2L V10 w/ Twin Turbo
- Viper V10 swap
- 1GZ-FE swap
- 426 Hemi swap
- Second FA20 installed behind front seats (Audi TT Bimoto style)
- Bugatti Veyron W16 swap + AWD
- Jet engine swap

In all seriousness though, I really am more interested in an Ecoboost swap. Perhaps that has more potential for compound boost.

[Spartarus]

Originally Posted by jsimon7777

Deja vu here from the VitTuned thread.

It's 'cause Vit was right. And @CSG Mike is right

Originally Posted by Jaden

Pressure is NOT meaningless.

Show me a real world example of a low displacement engine making high power on low boost.

You can't because it doesn't exist.

you CANNOT GET high flow in a low displacement engine without HIGH BOOST.... PERIOD.

Ptuning made 298 WHP on 6 lbs of boost, on pump gas, with a GT30 Turbo.

If that doesn't wake you up, I don't know what will.

More learning. Less declaring.

Pressure does not equal density

[Jaden]

Originally Posted by Spartarus

It's 'cause Vit was right. And @CSG Mike is right



Ptuning made 298 WHP on 6 lbs of boost, on pump gas, with a GT30 Turbo.

If that doesn't wake you up, I don't know what will.

More learning. Less declaring.

Pressure does not equal density

I'm not the one that needs to do more learning 300 wheel horsepower at 6 PSI is not out of the realm of feasibility for a 2 liter engine 500 at 6 PSI is

But I promise you that there was a lot more flow modifications done to that engine then just it running 6 PSI of boost.

Vit and Mike are both full of shit because they're confusing turbo airflow with engine airflow. power generation is all about engine airflow. boost icreases engine airflow by raising the effective displacement.more psi equals more displacement


jaden

[Spartarus]

Originally Posted by Jaden

I'm not the one that needs to do more learning 300 wheel horsepower at 6 PSI is not out of the realm of feasibility for a 2 liter engine 500 at 6 PSI is

But I promise you that there was a lot more flow modifications done to that engine then just it running 6 PSI of boost.

Vit and Mike are both full of shit because they're confusing turbo airflow with engine airflow. power generation is all about engine airflow. boost icreases engine airflow by raising the effective displacement.more psi equals more displacement


jaden

Airflow raises airflow.

More PSI does not mean more displacement, more mass means more displacement.

They aren't full of shit.

Why can one turbo make 300 WHP on 6 PSI, when another makes 250 on 7 PSI with the same intercooling, and the same AFR's?

Boost is loosely correlated with charge density and airflow. It's one variable of many.

Conceptually, though, you are in the ballpark about compound boost. You've got a few major misconceptions to correct.

[Jaden]

Originally Posted by Spartarus

Airflow raises airflow.

More PSI does not mean more displacement, more mass means more displacement.

They aren't full of shit.

Why can one turbo make 300 WHP on 6 PSI, when another makes 250 on 7 PSI with the same pipes, the same intercooling, and the same AFR's?

and how exactly do you get an engine to take more mass?I'll go ahead and answer that question fir you, you increase boost..duh that's the whole point of forced induction.

Because the airflow of the turbo is different and the valve lift and duration is different. but increasing turbo airflow has a limit that is defined by the displacement of the engine and the flow that the intake and exhaust components allow....higher boost increases the effective displacement which allows the engine to flow more air beyond the limits of the valve train and exhaust.

jaden

[CSG Mike]

Originally Posted by Jaden

I'm not the one that needs to do more learning 300 wheel horsepower at 6 PSI is not out of the realm of feasibility for a 2 liter engine 500 at 6 PSI is

But I promise you that there was a lot more flow modifications done to that engine then just it running 6 PSI of boost.

Vit and Mike are both full of shit because they're confusing turbo airflow with engine airflow. power generation is all about engine airflow. boost icreases engine airflow by raising the effective displacement.more psi equals more displacement


jaden

Let me sell you a blowtorch.

[CSG Mike]

Originally Posted by Jaden

and how exactly do you get an engine to take more mass?I'll go ahead and answer that question fir you, you increase boost..duh that's the whole point of forced induction.

Because the airflow of the turbo is different and the valve lift and duration is different. but increasing turbo airflow has a limit that is defined by the displacement of the engine and the flow that the intake and exhaust components allow....higher boost increases the effective displacement which allows the engine to flow more air beyond the limits of the valve train and exhaust.

jaden

Since you obviously don't get it, let me just tell you.

I can increase boost by heating up the air. That increased boost still did not increase the mass of air going into the engine.

I get 550whp out of a F20C with 9.5 psi of boost.

[CSG Mike]

Originally Posted by CSG Mike

Your prowess as an engineer is made apparent by your overabundance of speculation paired with sore lack of results.

As I've previously said, I'll gladly eat my words if you can provide a proof of concept. Right now, you've accomplished as much as a five-year-old child threatening to run away. Put your money where your mouth is.

Quoting myself for emphasis.

[Spartarus]

Originally Posted by Jaden

and how exactly do you get an engine to take more mass?I'll go ahead and answer that question fir you, you increase boost..duh that's the whole point of forced induction.

Because the airflow of the turbo is different and the valve lift and duration is different. but increasing turbo airflow has a limit that is defined by the displacement of the engine and the flow that the intake and exhaust components allow....higher boost increases the effective displacement which allows the engine to flow more air beyond the limits of the valve train and exhaust.

I suppose we will start at the beginning. Only basics at this point.

Increasing boost to make the engine move more air only works if you're not losing density as fast as you're adding pressure. That's part of the reason why non-intercooled turbo setups have a huge diminishing return in power as you raise boost.

Hence Mike's comment about cooling all of this boost.

If you can't maintain charge density, all you're doing is moving vertically on the compressor map, pumping the same mass of air at an ever-increasing pressure ratio, and ever diminishing efficiency, until you cross the surge line. You won't actually get any more air mass into the cylinder.

The rest of this chat is for another time and more beer.

EDIT: Oh, that whole statement was redundant. Mike already proved my point. Throw out your intercooler, get an interheater. Yay boost!

When it comes down to a choice between "many of those vastly experienced forced induction tuners must be full of shit" and "I may be misunderstanding things" What do you honestly think the right answer is?