How much hp equals 10 lbs/min (exhaust related, trouble reading turbine flow maps)

[definitiveno]

I am trying to figure out what turbine wheel and housing I want to put on my car but I don't know how to calculate HP (or air consumption) vs rpm into lbs/min in exhaust flow.....

I think fuel trimming can vary the results of lbs/min but I suppose I can use a median entry and go from there.

 

[Slippi84]

I am trying to figure out what turbine wheel and housing I want to put on my car but I don't know how to calculate HP (or air consumption) vs rpm into lbs/min in exhaust flow.....

I think fuel trimming can vary the results of lbs/min but I suppose I can use a median entry and go from there.

It varies but most of the time it's 10whp = 10 lbs/min

 

[definitiveno]

Your thinking of how lbs/min into the motor, I want to know how many lbs/min comes out of the motor.

 

[Slippi84]

WHy would you use that to figure out which exhaust wheel. Just curious as I know you have a interesting reason.

 

[CanadianTSi]

It varies but most of the time it's 10whp = 10 lbs/min

I think you mean 10whp equals 1lb/min.

And the same amount of air comes out that goes in...

 

[definitiveno]

I need to know how much exhaust my car will potentially produce so that I can confidently know I have a wheel and housing combo that can effectively process the gas without creating a restriction. The turbine graphs provided by garrett give flow capabilities in terms of lbs/min, I imagine so that one could try and figure out what "fits" there system. When I look at the gt35r (or at least the compressor half) there are a handful of flow options to choose from varying in turbine size and A/R (to include the gt30r turbine configurations wich can be retrofitted). Just trying to make some sense of them

 

[definitiveno]

I think you mean 10whp equals 1lb/min.

And the same amount of air comes out that goes in...

No it doesn't, actually little to no "air" comes out as most gets burnt up in the combustion process. In terms of volume, only about half comes out that goes in.


Look at a ohv head, even our own 4g63, and ask why the exhaust ports are smaller.

 

[Slippi84]

I think you mean 10whp equals 1lb/min.

And the same amount of air comes out that goes in...

Yeah your right about the 1lb/min = 10whp as for the same amount of air going in as going out I don't know if that's true or not but to the Original poster what are your hp and or et/mph goals and we can help you out with which wheel and exhaust housing to go with. to be honest a .82 t3 housing is more than enough for most applications.

 

[definitiveno]

Yeah, see, I don't really have a figure for that. I would prefer to just learn about these graphs and figure out how to apply the information instead of assuming since setup X worked for dsmtuner snuffy that it should work for me.

 

[CanadianTSi]

Sorry Air was the wrong word to use, more like "gases"

But as for less comes out, how could that be possible? things can't just dissappear.

 

[joe]

Sorry Air was the wrong word to use, more like "gases"

But as for less comes out, how could that be possible? things can't just dissappear.

thats what I was thinking

 

[definitiveno]

Much of the molecules are burnt and disintegrated leaving lesser byproduct by volume than in original form.


One bad analogy, if you put a block of wood into a fire it will reduce in mass substantially.

 

[Slippi84]

To be honest your trying to get to technical with this man you don't have to go by what others have done as I agree that cars vary so much even with the same mods but all you have to do is go find a exhaust side setup (blade and housing) that matched with the proper compressor setup is rated to 100hp over your goal and that is the turbo setup you want to go with.

 

[definitiveno]

, thats what I am trying to do here. If I can learn how to figure out what each turbine blade and housing is worth (hp wise) via garrett's maps, I can decisively know for certain which combination will work for me.

I am leaning towards your above recommendation with a T3 .82 A/R (gt30r hotside) since it seems the most efficient, but I don't quite understand fully the values offered in the turbine maps. If there is a way, I would like to be able to read and calculate definitively why that recommendation is accurate instead of leaping with blind faith into a 1300 dollar purchase.

 

[nanokpsi]

Just use the turbine maps as a refrence to compare to eachother relatively. For example, if you want a gt4094r to flow like a 4294r with the 1.01ar hotside, then you need to get the 1.19.
Also, look at all the poeple you see make awesome power with a 35r using the .63 housing and see that it doesn't even flow 25 lb/min.

 

[definitiveno]

see that it doesn't even flow 25 lb/min.

I don't even know if that is good or bad, I just want to learn how to read turbine maps. I read alot about others success's, and that is fine, but for every 1 success there is 5 mediocre stories and 3 nightmares. I don't want to be either of the 8 other guys. To take your word or the experience of some one else and risk overlooking a detail of there setup that doesn't quite fit with my own, forget it.


You know honestly, ive never had people on this forum tell me I am getting too technical before. Usually tuners are the ones bringin the tech to me. If you simply don't know how to read a turbine map thats cool, neither do I. Just don't give me recommendations for stuff some one else used, because I search alot too. I already know what every one else is using (as long as they disclose what there using). I figured I would take the opportunity to expand my lack of a knowledge in this topic and learn a little bit more about my turbo system. The reward is two fold since I am currently shopping and ive always been curious to know how to read and understand the hotside of the turbo.

 

[definitiveno]

Let me reiterate on my last post, don't give me recommendations unless you can tell me why with a reason other than it worked for dsmtuner snuffy.

Also if you are curious about this topic like me here is an interesting page of information, not what I wanted but very organized and detailed none the less.

http://www.turbomustangs.com/turbotech/main.htm

 

[yukondoit]

you need to understand conservation of mass, mdot in = mdot out. mass is neither created or destroyed so to understand what is in the exhuast housing start at the intake.

so your goals are 300 hp. so from the general rule of thumb, 1lb/min = 10 hp so thats 30lb/min of air entering the motor. now you have to consider fuel. 11 to 1 is a safe mixture so for 30 lbs/min of air you need approx 2.72 lbs of fuel per min, so your exhuast mass flow rate is 32.72 lbs/min.

hope this helps.

 

[Caithness]

Also, look at all the poeple you see make awesome power with a 35r using the .63 housing and see that it doesn't even flow 25 lb/min.

We have to take into account the amount of exhaust gas that escapes through the wastegate, too. That should make up a good bit of the difference.

That's not to say I have a clue what it means even if the wastegate gas does equal the other 25 lb/min on a 50 lb/min air+fuel intake. I still have no idea how you read these maps. Good thread topic- hopefully somebody can come in here and clear up the mystery before I spend 6 hours searching google for the answer.

 

[MILITISINVICTUS]

I thought the concept was Conservation of Matter?

 

[yukondoit]

mechanical engineering we use conservation of mass, we dont are about matter, protons netrons or electrons.

to find out how much is flow through the wastegate you would have to know the manifold pressure, dump pressure and diameter of the wastegate.

after looking at the turbine maps i believe you would have to account for the wastegate and that the graph shows how much the turbine will flow at a given pressure ratio meaning, the rest must go through the waste gate or the raise the pressure ratio ( boost creep).

 

[nightspeed87]

We have to take into account the amount of exhaust gas that escapes through the wastegate, too. That should make up a good bit of the difference.

That's not to say I have a clue what it means even if the wastegate gas does equal the other 25 lb/min on a 50 lb/min air+fuel intake. I still have no idea how you read these maps. Good thread topic- hopefully somebody can come in here and clear up the mystery before I spend 6 hours searching google for the answer.

im sure youd be the one to figure it out

, thats what I am trying to do here. If I can learn how to figure out what each turbine blade and housing is worth (hp wise) via garrett's maps, I can decisively know for certain which combination will work for me.

I am leaning towards your above recommendation with a T3 .82 A/R (gt30r hotside) since it seems the most efficient, but I don't quite understand fully the values offered in the turbine maps. If there is a way, I would like to be able to read and calculate definitively why that recommendation is accurate instead of leaping with blind faith into a 1300 dollar purchase.

I know your trying to find the technicals of the matter in detail to learn something but far as picking the part honestly;maybe a stupid question but I dont see why just going with the biggest size available would hurt since isnt it true that technically you dont need backpressure in your exhaust system anyways its not like you can go too big right? Maybe ive got this wrong, but basically im assuming the more flow the better; besides then youd still have room to expand if your goals rose in the future; so id get the best flowing setup theyve got. Also considering they might or might not have taken account for the wastegate air, or a car with o2dump- in their charts unless they mean the flow before it hits that point?

 

[drivemusicnow]

Heh... wow this thread is spiralling no where:

OKay First, there is a "law" of conservation of mass. Read Wikipedia

Mass in = mass out in a closed system.

This means that WHATEVER mass is put into the cylinder, that same mass is coming out. Youcandoit's example is correct.



VOLUME is not the same as MASS. the air going into the cylinder is a very tightly compressed small volume, high mass amount of air. The exhaust is extremely HOT, and therefor expands very quickly (the basis of how internal combustion engines work)

As far as turbine efficiency maps, there are a few points to consider. I'll preface this with the fact that I am not all that familiar with them, however I have pretty good ground knowledge in thermodynamics and the following makes sense to me. PLEASE correct me if I mis-state something.

On a compressor map, you look at the efficiency range that your engine will be at maximum load. When looking at a turbine map, I would think that you would want to maximize efficiency well before maximum load. For example, you want your turbine to be most efficient BEFORE you open your wastegate, as that is when it makes a difference. After the wastegate opens, you have no real need for "efficiency" per se, as you can always close the wastegate to gain more energy through the turbine.

So, if we use an example of say a GT35R (all these numbers are made up by the way) Say we are running 25 lbs of boost, and we get this boost by 4200 RPM. We want the Turbine to be most efficient in the 3000-4200RPM range (to increase spool and power) without choking the engine up top by not being able to flow enough to KEEP that 25 psi too redline. I would think that you would want to solve your lbs/min of airflow at this much lower RPM range (would probably be around 19-25 lbs/minute, and then add in your fuel lbs/min. This would be your target for the efficiency range of the turbine.

Again, this makes sense to me, but could be entirely wrong. I would probably suggest contacting FP, or some other Turbo guru about such concepts.

 

[nightspeed87]

makes sense to me but I just thought of this; even after the w.g. opened it still has to effectively flow the exhaust that still does see the turbine so then again your still trying to effectively flow the same amount thru that section as before it opened since any extra air made from more boost (that wouldve caused over boosting) is now directed out the w.g. but im assuming technically the turbine side hole still sees the same flow rates (probably this will differ more so if you have external/ internal w.g.)

 

[yukondoit]

Heh... wow this thread is spiralling no where:

OKay First, there is a "law" of conservation of mass. Read Wikipedia

Mass in = mass out in a closed system.

This means that WHATEVER mass is put into the cylinder, that same mass is coming out. Youcandoit's example is correct.



VOLUME is not the same as MASS. the air going into the cylinder is a very tightly compressed small volume, high mass amount of air. The exhaust is extremely HOT, and therefor expands very quickly (the basis of how internal combustion engines work)

As far as turbine efficiency maps, there are a few points to consider. I'll preface this with the fact that I am not all that familiar with them, however I have pretty good ground knowledge in thermodynamics and the following makes sense to me. PLEASE correct me if I mis-state something.

On a compressor map, you look at the efficiency range that your engine will be at maximum load. When looking at a turbine map, I would think that you would want to maximize efficiency well before maximum load. For example, you want your turbine to be most efficient BEFORE you open your wastegate, as that is when it makes a difference. After the wastegate opens, you have no real need for "efficiency" per se, as you can always close the wastegate to gain more energy through the turbine.

So, if we use an example of say a GT35R (all these numbers are made up by the way) Say we are running 25 lbs of boost, and we get this boost by 4200 RPM. We want the Turbine to be most efficient in the 3000-4200RPM range (to increase spool and power) without choking the engine up top by not being able to flow enough to KEEP that 25 psi too redline. I would think that you would want to solve your lbs/min of airflow at this much lower RPM range (would probably be around 19-25 lbs/minute, and then add in your fuel lbs/min. This would be your target for the efficiency range of the turbine.

Again, this makes sense to me, but could be entirely wrong. I would probably suggest contacting FP, or some other Turbo guru about such concepts.

I believe your on the right track, but in order to relate turbine to compressore you'll need first law equation or its varient renolds transport theorom in order to relate the shaft work supplied buy the turbine and the shaft work required for the compressor. This is were the effiecencies of both the comprosser and turnbine as it would increase the amount of work necessary.