Compound boost.

[camelflage]

a lot of buildup, no release...

6/10 stars

[Jaden]

Originally Posted by iamjacob

LOL I wasn't the one talking about bitch slapping someone. But Yes, I AM a bad ass...

Jaden

[Jaden]

i've decided to just ignore the assholes and still put out the good information...

Earlier I talked about how the secondary's airflow isn't as important and it becomes trickier to determine what it needs to be so here is a calculation that references secondary flow requirements.

<quote>
For the small turbo, determining the MAF capabilities is a little more tricky because the compressor maps are generated at atmospheric pressure (1 Bar) and at 25 deg. C (298 deg. K), and the MAF capabilities of a compressor changes in accordance with both of these parameters. So, in order to determine the MAF capabilities of the small turbo in this particular setup, a MAF correction factor (MAFcorr) must be generated so that we can still use the published map. The equation to do this is:

MAFcorr = MAF * ((Tin2/Tref) / (Pin2/Pref))^0.5

where

Tin2 is the temperature in deg. K of the intake charge into the small turbo compressor (from the large turbo compressor), Tref = 298, Pref = 1, and Pin2 is the absolute pressure of the intake charge into the small turbo compressor in Bars (boost pressure in bars + 1 bar).

Tin2 = Tin1 + (Tin1 * ((Pin2/Pin1)^0.15) - 1)/eff

where Tin1 is the intake air temperature into the large turbo and Pin1 is atmospheric pressure, and eff is the efficiency of the large turbo at the pressure ratio/MAF point on the compressor map.

To convert from deg. C to deg. K, add 273 to the deg. C reading. To convert from deg. F to deg. K, K = (F + 459.67)*(5/9). Alternatively, just use this conversion web site: http://www.onlineconversion.com/temperature.htm. Also, remember that the air flow has not yet been cooled by the I/C.

The MAF correction factor and boost ratio of the small turbo charger then can be plotted on the small turbo's compressor map.


Example #1

Displacement: 3.5 L
Desired power: 1000 whp
Setup: Quad turbo (compound turbos for each bank)
Computed MAF: 54.5 lb/min per side
Computed Boost (above atmosphere): 36.2 psi (2.5 Bar)
Intake Air Temp: 77 deg. F, (25 deg. C, 298 deg. K)

Bt = 2.5 Bar + 1 Bar = 3.5 Bar

To divide the boost up evenly, let's try:

Bbt = Bst = 3.5^0.5 = 1.87

Based on the compressor map for the GT3582, it will not flow 55 lb/min at a pressure ratio of 1.87 with adequate efficiency. So lets try a GT4088R (yes it will be hard to find a place to fit this, but let's ignore that for this example).

At Bbt = 1.9, the GT4088R flows 54.5 lb/min at 70% efficiency

Tin2 = 298 + (298 * ((1.9^0.15) - 1)/0.70 = 349 deg. K

MAFcorr = 54.5 * ((349/298)/(1.9/1))^0.5 = 42.7 (use as lb/min value in published map)

So, for the small turbo, we need a turbo that flows 42.7 lb/min at a 1.9 pressure ratio. The GT2876 just makes it. It will flow 42.7 lb/min at about 65% efficiency.


In contrast to example #1, if the turbos were available with larger compressor inducers (e.g., higher trim values), then we could use a GT3582/GT2871 combination. This would give us the hp of the GT3582 with the turbo lag of the GT2871.

At Bbt = 2.3, the GT3582 flows at 73% efficiency.
Bst = 3.5/2.3 = 1.5
Tin2 = 365 deg. K
MAFcorr = 39.7

Although the GT2871 will flow 39.7 lb/min, not at a pressure ratio of 1.5. At that pressure it is beyond the choke line. With a 56 Trim, 0.60 A/R, it needs about a 1.8 pressure ratio to get to the required air flow. With the right compressor blades it could get there at a pressure ratio of 1.5, though. I'm speculating that a trim in the range of 60 - 70 might work, but that is just my guess by comparing the 48 and 56 trim maps.

<quote>
The above is a quote from another forum.
If people want to get into an explanation of the above I'll be happy to sans the BS comments...

Jaden

p.s. if you have good intercoolers that keep the charge relatively close to ambient(ambient being relative to the intake charge on each FI system), you can get close to the same efficiencies as listed on the map. This should answer Mike's question as to how you keep the boost cool. So long as you are intercooling the charge between systems, the intake temperature from charging the precharged air coming from the primary system isn't much more than the secondarywould be by itself...

[Toyarzee]

Originally Posted by Jaden

It's better to suck cock and be an idiot than to gain knowledge and not be an idiot at all...

Jaden

Your prowess as an engineer is very apparent with your technical discussion of cock sucking

Originally Posted by Jaden

LOL I wasn't the one talking about bitch slapping someone.

Uh.... you sure?

Originally Posted by Jaden

I'll be happy to meet up with you for you to "attempt" to bitch slap me...lol

Jaden

Honestly, monkey math was putting it nicely. You promised to stop posting btw

[Jaden]

Originally Posted by Toyarzee

Your prowess as an engineer is very apparent with your technical discussion of cock sucking



Uh.... you sure?



Honestly, monkey math was putting it nicely. You promised to stop posting btw

I promised no such thing nor will I... and as soon as one of you jawing idiots can post "REAL" math illustrating these concepts, then you might have accomplished something... It gets really fucking old when you put out good information and all people can do is post BS about monkey math without being able to post any corrections.. You detract from people who might otherwise actually learn something and THAT pisses me off more than anything.

My prowess as an engineer is apparent by the patents I own...


Jaden

[Toyarzee]

Originally Posted by Jaden

I promised no such thing nor will I...

My prowess as an engineer is apparent by the patents I own...


Jaden

See below

Originally Posted by Jaden

You people are fuckin ridiculous... Good bye for a while...

For those of you who would've liked to get some good info about compound charging... Sorry, the assholes who don't know their ass from a hole in the ground ruined it for you.

Jaden

And oh dear God, another crazy, quoting his patents... before going to bed at night, do remember to remove your tin foil hat. Let's see those patents since your so into probing yourself... i mean proving yourself

[KR-S]

Originally Posted by Jaden

I promised no such thing nor will I... and as soon as one of you jawing idiots can post "REAL" math illustrating these concepts, then you might have accomplished something... It gets really fucking old when you put out good information and all people can do is post BS about monkey math without being able to post any corrections.. You detract from people who might otherwise actually learn something and THAT pisses me off more than anything.

My prowess as an engineer is apparent by the patents I own...


Jaden

[CSG Mike]

Originally Posted by Jaden

I promised no such thing nor will I... and as soon as one of you jawing idiots can post "REAL" math illustrating these concepts, then you might have accomplished something... It gets really fucking old when you put out good information and all people can do is post BS about monkey math without being able to post any corrections.. You detract from people who might otherwise actually learn something and THAT pisses me off more than anything.

My prowess as an engineer is apparent by the patents I own...


Jaden

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.

[CSG Mike]

Originally Posted by Jaden

i've decided to just ignore the assholes and still put out the good information...

Earlier I talked about how the secondary's airflow isn't as important and it becomes trickier to determine what it needs to be so here is a calculation that references secondary flow requirements.



The above is a quote from another forum.
If people want to get into an explanation of the above I'll be happy to sans the BS comments...

Jaden

p.s. if you have good intercoolers that keep the charge relatively close to ambient(ambient being relative to the intake charge on each FI system), you can get close to the same efficiencies as listed on the map. This should answer Mike's question as to how you keep the boost cool. So long as you are intercooling the charge between systems, the intake temperature from charging the precharged air coming from the primary system isn't much more than the secondarywould be by itself...

So... how many intercoolers are you going to have?

[CSG Mike]

Why you constantly bring up pressure is beyond me. Pressure is MEANINGLESS.

I'm gonna go back to the most basic concept I can. PV=nRT

[EAGLE5]

Originally Posted by CSG Mike

Why you constantly bring up pressure is beyond me. Pressure is MEANINGLESS.

I'm gonna go back to the most basic concept I can. PV=nRT

Deja vu here from the VitTuned thread.

[weederr33]

Originally Posted by CSG Mike

So... how many intercoolers are you going to have?

Two plus a giant wing made out of another intercooler to get maximum aero and cooling!

[Jaden]

Originally Posted by CSG Mike

Why you constantly bring up pressure is beyond me. Pressure is MEANINGLESS.

I'm gonna go back to the most basic concept I can. PV=nRT

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 b/OOST.... PERIOD.


Yes airflow IN THE ENGINE is all that matters for power generation...


Airflow from the FI system is NOT engine airflow...


you fucking morons just don't seem to get that.


you could have a turbo that flows a million lbs a minute but the engine can only take a finite amount at a given rpm...


THE FUNNY thing about how stupid you sound is that YOU BROUGHT UP THIS EXACT POINT with your first monkey math comment.


It is the ability of the engine to flow 50 lbs of air at 3800 rpm that would allow 500 hp at 3800 rpm.


A big turbo can flow 50 lbs a minute at 3800 so why don't you think an engine can make that much???


BECAUSE THE ENGINE CAN ONLY FLOW SO MUCH AIR.


BOOST does ONE thing, it increases the effective displacement so that the engine can flow more air.


IF the turbo or S/C that you have flows more air than the engine can take, you WON'T make the power.


That's where compound boost helps you, because if your primary has more airflow at a boost level that is too low in the rpm band for your engine to flow that much air, you up the boost on the secondary increasing the effective displacement of the engine so that it can swallow the airflow your primary is putting out.


But at the same time, if your primary can't put out the airflow at a given boost (read effective displacement) that the engine can flow, you STILL won't make the power that you expect to and are capable of.


Again, your idiocy in regards to this is evident by your lack of understanding that boost AND FI flow is both necessary to make up for lack of displacement and therefore lack of ENGINE airflow...


Jaden


p.s. I would've stated this in a much more tactful manner if you guys weren't being so condescending in your attitudes.

[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...