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

[drivemusicnow]

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.

You are, obviously, correct is saying that the work done by the compressor at full engine load needs to be provided by the turbine. This work is obviously more than the work done by the compressor at full boost/4200 rpm. As long as the turbine can provide that work at full load, you should be okay. We don't care really if it is efficient at full load, because any extra efficiency will be countered with venting off exhaust flow through the wastegate.

I don't know if I even want to start down that path at this point. I mean, we probably have some the data points we need, but since this is on a theoretical system, you don't really know changes in pressure and temperature accross the turbine/compressor. I say since the problem is theoretical, we just stick with theory, and until we have the need to actually solve the problem.

 

[DSMunknown]

Click below for a decent reading on how to read flow maps:









http://www.automotivearticles.com/123/printer_Turbo_Selection.shtml

 

[drivemusicnow]

That article has a couple of minor errors in it. It also doesn't really address the OP's question which is specific to turbine maps, and how to choose the "best" one. It does however offer a good explanation of compressor maps, and is good information that we should probably put on Tuners in a tech article somewhere.

 

[Kevin Jewer]

Yukondoit and drivemusicnow are both correct enough for me and my limited knowledge. The simplest way to look at turbine side selection though, and the way I do it, is to go with the largest turbine side that your personal lag tolerance will allow. For a given compressor, larger hot sides make more power. There is obviously a point of deminishing return here, but that goes with out saying. And also, naturally, you could make the turbo so laggy that the ETs go to complete shit. But this is where "lag tolerance" comes in and keeps things in check. There are many examples of people running a large turbine side and a small compressor side, relative to each other, that run very quick ETs for the what the setup is. The theory is that the larger hot side gives maximum benefit, while the smallest comp wheel you can get away with will reduce inertial overhead countering the added lag from the larger hotside.

 

[nightspeed87]

this appears to have a lot of useful info http://dsmtuners.com/forums/showthread.php?t=199534&page=2

 

[Slippi84]

With how much thought your putting into this hot side selection you better be trying to make a 9 second car or something.

 

[definitiveno]

With how much thought your putting into this hot side selection you better be trying to make a 9 second car or something.

Why is that? I am not trying to build a super fast car (imo), just trying to make whatever money I put into my car work the best it possibly can for me.


Should your suggestions turn out to be correct, do not blame me because you couldn't adequately explain why when I asked.

I don't know if I even want to start down that path at this point. I mean, we probably have some the data points we need, but since this is on a theoretical system, you don't really know changes in pressure and temperature accross the turbine/compressor. I say since the problem is theoretical, we just stick with theory, and until we have the need to actually solve the problem.

Now given enough parameters is there a way to figure out what type of volume the car might potentially produce? Given hp or intake consumption, rpm, things like this? I don't want to waste your time spouting off things I think might fit the parameter so if you could tell me what type of information needed I would be very greatful of your help.

 

[nanokpsi]

With how much thought your putting into this hot side selection you better be trying to make a 9 second car or something.

I've been holding back a similar remark, but felt it wouldn't serve his "goals".

Learning how to read a turbine map isn't going to keep you from having a bad experience or bad results form a turbo. When your going with such a common turbo (believe it or not, a few people with 2.0 motors have run a gt30r before...) its is much easier to go based on other people's experiences. These small compressors can be maxed out relatively easily on our motors and since you wanted a longer powerband (taken form your other thread) I suggested a hotside that was more than capable of doing so.

I am all for you wanting to learn more, and if you are looking for a formula or more in depth information on reading turbine maps, plug it into google. FWIW you're going to have trouble finding turbine maps for all the common "old style" turbos so you'll be forced to go by others experiences or mock up a back pressure gauge.

 

[definitiveno]

Wow, never seen discouragement to learn on the boards before

When your going with such a common turbo (believe it or not, a few people with 2.0 motors have run a gt30r before...) its is much easier to go based on other people's experiences.

I am plenty aware, and never said it wasn't. You guys are acting like I am insulting you by not banking on your recommendations when all I am trying to do is (read the thread title again) figure out how to read turbine maps for my own personal satisfaction.

 

[drivemusicnow]

Wow, never seen discouragement to learn on the boards before



I am plenty aware, and never said it wasn't. You guys are acting like I am insulting you by not banking on your recommendations when all I am trying to do is (read the thread title again) figure out how to read turbine maps for my own personal satisfaction.

Well, give me some time (like until 10pm I just got home from work) I'll search the dsmlink forums for some data, and get back to you on what other things you would need.

Solving for lbs per minute should be easy, however solving for the range you want to be most efficient, as well as not choking the engine is hard. This would require figuring out the pressure ratios, flow through the wastegate at full load, work required to spin the compressor at full load, etc. (there are a lot of bits of information needed before you can solve for those numbers). The best way for you to start understanding exactly what is involved is to pick up a thermodynamics book at the library, and specifically look at the work equations for turbines and compressors. (I'd assume it's online somewhere as well. Wikipedia is a favorite resource of mine)

I do understand where you're coming from as far as wanting to know exactly what you are getting, however the easiest way to do this is order a FP3065, as I FULLY trust that FP has figured out (either just by testing, or by solving mathematically, and then also testing) what works on 4g63 motors. I would not put that same faith in SBR, PTE, or Bullseye for the bolt on mitsu housings. You could probably get an equally unsupported, yet very reliable suggestion as to a T3housing for a gt30 compressor as well by talking to the guys from FP.

 

[Boosted98gsx]

1 lb/min equates to about 11hp on a good tune.

 

[Rice Over Wheat]

Is that wheel or base hp? I noticed vendors always list their turbo ratings at 10:1 ratio for hp vs airflow. Example: 5031RE 450hp 45 lb/min. I always suspect they max rate in crank hp.

 

[Boosted98gsx]

Well an evo316g can flow 42 lbs/min and I've seen people get that high on a dyno, so I'd say that's wheel capable.

 

[Kevin Jewer]

People do tend to make that figure at the wheels, so I call it WHP. There are many examples of it. But of course chassis dyno numbers vary significantly by brand. Dynojet and Land and Sea are the most optimistic (and match most of the calculations based on trap speed), Mustang reads 12-15% lower, and DynoDynamics reads even lower than that.

 

[Rice Over Wheat]

Hm, well that's good to know. I'm pretty embarassed that my T28 is only flowing 28 lb/min at 21 psi. So that makes me feel a bit better.

 

[yukondoit]

Inertia dynos tend to read high (dyno jet, some land and sea) if you want to torture test your systme put it at steady state and tune it. personally i've had engine at full load full rpm for 10 minutes. granted it wasnt a 4g63 though.

 

[definitiveno]

Inertia dynos tend to read high (dyno jet, some land and sea) if you want to torture test your systme put it at steady state and tune it. personally i've had engine at full load full rpm for 10 minutes. granted it wasnt a 4g63 though.

Sounds crazy, was it a diesel engine you did this to?

 

[Slippi84]

Wow, never seen discouragement to learn on the boards before



I am plenty aware, and never said it wasn't. You guys are acting like I am insulting you by not banking on your recommendations when all I am trying to do is (read the thread title again) figure out how to read turbine maps for my own personal satisfaction.

I am not discouraging him from learning just it seems to me like he's trying to reinvent the wheel. I already stated all you have to do is look at what the vendors rate the turbos flow not hp to use 1 lb/mn= 10whp subtracts 100hp = 10lbs/min from what the vendor is saying the turbo will flow and that should be where your goal is. Example if you want a 350whp car buy a turbo that the vendor says will flow atleast 45lbs/min.

 

[drivemusicnow]

Okay,

So I looked through a couple random GT30R logs and I couldn't quite find what I wanted. One of the logs I found is a 3rd gear pull, starting from low rpm. In this log, at3000RPM he was seeing about 10-11 lbs/min of airflow (7.5 psi), and at 4500 rpm, it's at about 30 lbs/minute (23.7 psi.) Wastegate opens at ABOUT 3800 rpm, at which point it is flowing about 25 lbs/min.

convert those to exhaust flow is about 12lbs/min to 32.5 lbs/minute. Then you would need pressure drop accross the turbine (pressure in manifold versus pressure in o2 housing, use absolute pressures) this should give you a line to plot on the turbine maps and see which one is better.

To realize that any modifications to the VE of an engine will change the above values, and, for example, using cams or SMIMs will significantly change the slope of the line.

 

[yukondoit]

haha not diesel, cbr 954 engine on e10 with a powercommander, five gas analyzer and land and sea water break dyno


drivemusicnow, so your thinking it would have to be experimental, get both trims then test. this is what i've read in a couple books and from our tech at IHI. we're turbocharging a parallel twin this year and IHI says that choking is even more apparent in twin cylinder engines.

back on topic you best source is to talk to a rep or spend lotsa money and test them both.

 

[Boosted98gsx]

Okay,

So I looked through a couple random GT30R logs and I couldn't quite find what I wanted. One of the logs I found is a 3rd gear pull, starting from low rpm. In this log, at3000RPM he was seeing about 10-11 lbs/min of airflow (7.5 psi), and at 4500 rpm, it's at about 30 lbs/minute (23.7 psi.) Wastegate opens at ABOUT 3800 rpm, at which point it is flowing about 25 lbs/min.

A GT30R only flowing 30lbs/min at 23 psi? That should be in the mid 40's AT LEAST. There was something wrong with his setup.

 

[nanokpsi]

back on topic you best source is to talk to a rep or spend lotsa money and test them both.

FWIW turbine housings only cost 100-150 bucks.

 

[Kevin Jewer]

I am not discouraging him from learning just it seems to me like he's trying to reinvent the wheel. I already stated all you have to do is look at what the vendors rate the turbos flow not hp to use 1 lb/mn= 10whp subtracts 100hp = 10lbs/min from what the vendor is saying the turbo will flow and that should be where your goal is. Example if you want a 350whp car buy a turbo that the vendor says will flow atleast 45lbs/min.

That makes no sense to me. There are countless examples of people making 10 times their lbs/min readings at the wheels.

A GT30R only flowing 30lbs/min at 23 psi? That should be in the mid 40's AT LEAST. There was something wrong with his setup

That will be peak airflow though. The RPM figures in that quote are quite low (4500). I'm sure at 6500 rpm or so the airflow was much higher.

 

[Slippi84]

That makes no sense to me. There are countless examples of people making 10 times their lbs/min readings at the wheels.




That will be peak airflow though. The RPM figures in that quote are quite low (4500). I'm sure at 6500 rpm or so the airflow was much higher.

That's fine and dandy but like he said he isn't gonna buy something based upon what others have or haven't done he wants to base his choice on something more reliable. I don't see how it wouldn't make sense to someone like you as it's not the first time it has been stated on these forums.