When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Here I report a very simple comparison in term of maximum flow rate and compressor wheel dimension for the most common turbines. Dimensions of wheels are calculated as the geometric mean between the inducer and the exducer. This kind of mean is quite consistent since the inducer is more important than educer to produce the flow. Sorry for the italian on the axis.
There are certain other aspects that play a very significant role in the cfm output of a wheel other than its overall dimensions. Factors such as the type of aerodynamic design, the blade surface area, the material and weight of the wheel.
There are certain other aspects that play a very significant role in the cfm output of a wheel other than its overall dimensions. Factors such as the type of aerodynamic design, the blade surface area, the material and weight of the wheel.
Marios
Yes I know, fluid dynamics is highly non-linear, but this is a simple comparison in terms of only two parameters. The choice of turbocharger must be made by evaluating the flow map.
Yes I know, fluid dynamics is highly non-linear, but this is a simple comparison in terms of only two parameters. The choice of turbocharger must be made by evaluating the flow map.
That is why I mentioned the rest of the parameters, as basing your choice of a turbo on just the advertised compressor map's flowing characteristics and on the mere dimensions of the compressor wheel is not enough. Firstly because most compressor maps are either exceeded most of the times in actual max flow by the turbocharger as a complete unit which includes the turbine wheel, or the turbocharger might not actually flow what its advertised compressor map dictates.
The above happens because all the other parameters I mentioned earlier fall into perspective.
Advertised compressor maps should always be considered as a dictated baseline of flow and they should be taken with a grain of salt.
I will add an example so that you can grasp with ease what I'm saying here. Let's take the 3076 unit. All the variations of this unit share the same dimensions, both in compressor and turbine wheels. But the gt3076r is rated at a flow of 550 hp, the gtx3076r gen 1 at 650hp and the gtx3076r gen 2 at 750hp. Granted all the other parameters have changed, apart from the overall dimensions, and have boosted the flow of the gt 550hp to the flow of 650hp on the gtx gen 1, I fail to see how the gtx gen 2 is going to flow the extra cfm needed to make 750hp, as all the parameters from the gtx 1 to the gtx 2 have remained substantially the same apart from a different design of the same type of the compressor wheel's aero.
The only changes they could have made, that would have made some cfm difference, but not enough to reach 750 hp, since they kept the same dimensions and type of aero, would be to increase the blade surface of the compressor wheel by reducing the center hub and increasing the blade angle. Also if they have provided the gen 2 with a different aero type turbine wheel along with less blades to reduce back-pressure at higher speeds.
Marios
Last edited by Evo8cy; Feb 2, 2018 at 12:30 PM.
Reason: typo
You need to take into consideration that the cfm output of a turbocharger is greatly affected by the turbine wheel in use.
For example the pte 6262 and the pte 6266 share the same compressor wheel, but the 6266 flows more due to its bigger exhaust wheel.
Marios
Intresting observation, you are right, but we need to take into occount of several aspects. Maximum flow itself depens only on the compressor properties and thus you can see it on the compressor flow map. On the other side (literaly ) the turbo (hot side) can be able or not to reach the choke line of the compressor map at maximum ehxaust flow. Precision give us not the flow map but the maximum power, thus we need to consider the maxium power declared at fixed compressor weel to eximate the maximum flow.
Originally Posted by Evo8cy
That is why I mentioned the rest of the parameters, as basing your choice of a turbo on just the advertised compressor map's flowing characteristics and on the mere dimensions of the compressor wheel is not enough. Firstly because most compressor maps are either exceeded most of the times in actual max flow by the turbocharger as a complete unit which includes the turbine wheel, or the turbocharger might not actually flow what its advertised compressor map dictates.
The above happens because all the other parameters I mentioned earlier fall into perspective.
Advertised compressor maps should always be considered as a dictated baseline of flow and they should be taken with a grain of salt.
I will add an example so that you can grasp with ease what I'm saying here. Let's take the 3076 unit. All the variations of this unit share the same dimensions, both in compressor and turbine wheels. But the gt3076r is rated at a flow of 550 hp, the gtx3076r gen 1 at 650hp and the gtx3076r gen 2 at 750hp. Granted all the other parameters have changed, apart from the overall dimensions, and have boosted the flow of the gt 550hp to the flow of 650hp on the gtx gen 1, I fail to see how the gtx gen 2 is going to flow the extra cfm needed to make 750hp, as all the parameters from the gtx 1 to the gtx 2 have remained substantially the same apart from a different design of the same type of the compressor wheel's aero.
The only changes they could have made, that would have made some cfm difference, but not enough to reach 750 hp, since they kept the same dimensions and type of aero, would be to increase the blade surface of the compressor wheel by reducing the center hub and increasing the blade angle. Also if they have provided the gen 2 with a different aero type turbine wheel along with less blades to reduce back-pressure at higher speeds.
Marios
My purpose with this graph was to give a rough idea of how new turbocompressors improves in their efficiency with the newest models. For example stock evo 9, tomei arms, hks etc are on the same line an this is quite remarkable since they coming from the same era. This means that, despite the elementary model used, the parameters are not totally pointless.
In any case I'm in agree with you, but it's impossible to classify turbos in a totally consistent way in a 2-D graph.
Intresting observation, you are right, but we need to take into occount of several aspects. Maximum flow itself depens only on the compressor properties and thus you can see it on the compressor flow map. On the other side (literaly ) the turbo (hot side) can be able or not to reach the choke line of the compressor map at maximum ehxaust flow. Precision give us not the flow map but the maximum power, thus we need to consider the maxium power declared at fixed compressor weel to eximate the maximum flow.
Precision was a mere example, the same thing happens with garrett turbos on which we get the advertised maps. It seems that you did not understand fully what I said. It does not matter if we have a compressor map or not. I will explain.
Let's just use garrett's 62mm compressor wheel that has a compressor map for us. Let's also use hp to simplify the discussion. The 62mm garrett gtx 1 compressor wheel is rated at 750hp as a max figure output of the garrett gtx3582r unit, with the specific wheel. And indeed the gtx 1 3582r turbo has been proven to make 700-750hp so the compressor wheel has already reached its max potential with the turbine wheel of the gtx3582 unit. Bear in mind that the pte 6262 unit has also the same output, their turbine wheels are also almost the same. So we can say that these two compressor wheels the gtx 1 and pte flow the same, and it is very logical as they have almost the same type of aero and dimensions. Now if we take garrett's gtx 1 wheel and use it with pte larger turbine wheel, then this hybrid turbo will flow even more, and the flow will exceed the existing compressor map's max value. Well this hybrid turbo is the 6266. That's why I said compressor maps are just a dictated baseline of a certain flow.
Another example to what I'm saying here is the following. Take into consideration the fact that the gtx35r 1 compr, wheel and the gtx35r 2 wheel have the same dimensions the same type of aero, but different advertised compressor maps, one is with higher max flow than the other and these are two maps of the same wheel.
My purpose with this graph was to give a rough idea of how new turbocompressors improves in their efficiency with the newest models. For example stock evo 9, tomei arms, hks etc are on the same line an this is quite remarkable since they coming from the same era. This means that, despite the elementary model used, the parameters are not totally pointless.
In any case I'm in agree with you, but it's impossible to classify turbos in a totally consistent way in a 2-D graph.
Well done to you for taking the time to do so, yes turbochargers have evolved enough the last 10-15 years. I'm not saying that you should present what I said on a graph, all I'm saying and trying to do here is that I'm trying to let you know what to take into account when you want to buy a turbo for a given application, not just to you, the info is for every member or not of this forum that is interested in this.
Tuscany makes great wine, also it is a beautiful place.
Precision was a mere example, the same thing happens with garrett turbos on which we get the advertised maps. It seems that you did not understand fully what I said. It does not matter if we have a compressor map or not. I will explain.
Let's just use garrett's 62mm compressor wheel that has a compressor map for us. Let's also use hp to simplify the discussion. The 62mm garrett gtx 1 compressor wheel is rated at 750hp as a max figure output of the garrett gtx3582r unit, with the specific wheel. And indeed the gtx 1 3582r turbo has been proven to make 700-750hp so the compressor wheel has already reached its max potential with the turbine wheel of the gtx3582 unit. Bear in mind that the pte 6262 unit has also the same output, their turbine wheels are also almost the same. So we can say that these two compressor wheels the gtx 1 and pte flow the same, and it is very logical as they have almost the same type of aero and dimensions. Now if we take garrett's gtx 1 wheel and use it with pte larger turbine wheel, then this hybrid turbo will flow even more, and the flow will exceed the existing compressor map's max value. Well this hybrid turbo is the 6266. That's why I said compressor maps are just a dictated baseline of a certain flow.
Another example to what I'm saying here is the following. Take into consideration the fact that the gtx35r 1 compr, wheel and the gtx35r 2 wheel have the same dimensions the same type of aero, but different advertised compressor maps, one is with higher max flow than the other and these are two maps of the same wheel.
They have a different trim, so they don't have the same wheel. The parameter I used is different. In addition to that, the graph I proposed can be useful to estimate the aerodynamic efficiency of wheel not the vice versa, you cannot assume similar properties a priori just because wheel look similar!
Finally the choke line which appear on flow map is calculated when the sonic condition approach. Cleary this condition cannot depends upon the turbine properties.
One last things; my english is not so good but my answer won't be offensive or crude, it's just poor of word
They have a different trim, so they don't have the same wheel. The parameter I used is different. In addition to that, the graph I proposed can be useful to estimate the aerodynamic efficiency of wheel not the vice versa, you cannot assume similar properties a priori just because wheel look similar!
Finally the choke line which appear on flow map is calculated when the sonic condition approach. Cleary this condition cannot depends upon the turbine properties.
One last things; my english is not so good but my answer won't be offensive or crude, it's just poor of word
Yes they do have a different trim but their actual lbs/min is the same in the real world. As I said there is more than one factor that makes a difference in a wheels max flow, not just the trim. What is important is that they flow the same in the real word, that's what I meant by being the same. The parameter you used is based on the dimensions of their inducer and exducer.
I do not know how you came to conclude about me considering that about your graph, but I assure you that is not the case. Also I have not mentioned anything about comparing or assuming a wheel's flowing capabilities just by looking at it, but when you have enough experience and knowledge on the matter, yes you can tell if a wheel will flow more than another by merely observing it.
Forget the choke line of the wheel you see on andvertised compressor maps. The actual sonic condition and choke line of the wheel begs to differ in reality. This is what I am trying to tell you. Advertised compressor maps are just a dictated baseline of flow. I can use cfd software to design compressor wheels and I have, I have also tried a great amount of things and testing in real life terms. The sonic condition and choke point of the compressor wheel depends on rpm and rpm depends on the turbine wheel.
Where have I been cruel on you through my posting mate?
Yes they do have a different trim but their actual lbs/min is the same in the real world. As I said there is more than one factor that makes a difference in a wheels max flow, not just the trim. What is important is that they flow the same in the real word, that's what I meant by being the same. The parameter you used is based on the dimensions of their inducer and exducer.
I do not know how you came to conclude about me considering that about your graph, but I assure you that is not the case. Also I have not mentioned anything about comparing or assuming a wheel's flowing capabilities just by looking at it, but when you have enough experience and knowledge on the matter, yes you can tell if a wheel will flow more than another by merely observing it.
Forget the choke line of the wheel you see on andvertised compressor maps. The actual sonic condition and choke line of the wheel begs to differ in reality. This is what I am trying to tell you. Advertised compressor maps are just a dictated baseline of flow. I can use cfd software to design compressor wheels and I have, I have also tried a great amount of things and testing in real life terms. The sonic condition and choke point of the compressor wheel depends on rpm and rpm depends on the turbine wheel.
Where have I been cruel on you through my posting mate?
Marios
Yes, I'm agree with you, but the problem, in this term, is how the flowing map is close to the real word. Clearly theoretical models and reality does not fit at 100%, especially in nonlinear problems. On the other side it's not possible to test every turbo until to find the right one, and the flowing map represent the only way to proper estimate the turbocompressor-engine coupling. But, I repeat that my intention, was to propose an immediate way to compare compressor with different technology applied over the years. Turbo-machines is a research field of specialist. Finally, nothing wrong with your post, i really appreciate the competent people. I was just making sure MY posts were not unpolished since the lot of people say that, maybe there something of very strange in my english.
) the turbo (hot side) can be able or not to reach the choke line of the compressor map at maximum ehxaust flow. Precision give us not the flow map but the maximum power, thus we need to consider the maxium power declared at fixed compressor weel to eximate the maximum flow.
