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Interesting, that's the first I've heard of someone choking git out on that big of an AR. Other 362 SXEs I've seen have made 700+ on E85 or with meth with a nice flat power curve on the top end, no significant drop off the tI would call choking. Do you have a dyno plot showing that choke at ~19psi? I
Firstly, me and raamo both were running the S360SX which has an old pretty average flowing 60mm cast wheel - so yes, we did hit choke at around 19psi but that's not due to the a/r of the exhaust housing - it's due to the compressor wheel running out of flow so you do start seeing symptoms of high exhaust manifold pressure as well, but that's more to do with the turbine having to try and work harder due to the compressor becoming seriously inefficient and needing to be spun harder to move any more air. The fact that the S360SX turbine wheel is also not great for flow relatively speaking is going to be a compounding factor (more on that shortly), but the main issue is the compressor flow imho.

Science!

Reached out to real street, they recommended the S364.5 sxe as a good option for the price with 500-600whp goals. Makes sense, use the same turbine wheel as the 360 and 362 to get the best response, but maximize the compressor side for pump gas goals. From the dyno plots I've seen with the 362, it doesn't choke up top ~620whp. Will be going with the 364.5 in either 0.68 open or 0.83 divided for a pump gas setup.
When we were choosing options for the RB30 we considered the S364.5SX-E but we wanted as much response as possible, seeing as it looks like people may not have analysed stuff as much as I did I might add some data which could prove helpful.

- The S364SX-E looks at a glance to flow a lot better than the S362SX-E but the real flow gains are mostly had at over pressure ratio 3.0, which doesn't seem helpful for an pump gas 3litre engine. If you look at the 2.2-2.6 pressure ratio range you're likely to operate in then the S364 may still at a glance look like it has big advantages but actually Borg Warner have mapped the S364SXE compressor map down to 54% compressor efficiency, which is pretty much useless. Anything under 60% efficiency is going to be generating a fair bit of heat and even if your intercooler is up to it - you're going to be needing increasing turbine energy to drive that compressor, which is going to drive up EMAP. For this reason I try and compare compressor maps "efficiency for efficiency", at which point the 64.5mm inducer/87mm exducer compressor has only 5lb/min more effectively flow most of the useful map than the 61.4mm/83mm compressor wheel. Maybe 6% more flow for a significantly larger compressor wheel, definitely larger by enough that you will loose spool and also at reasonable cost to transient response

- The "Use the same turbine wheel as the S360 and S362 to get the same response", going by this comment and other comments in here - thought I'd add that the S360SX and the S362SX-E use different turbine wheels. With our testing so far we've found basically no difference in spool between the two, but just to avoid any anecdotal evidence of how the S360SX turbine performed being used to determine a possible restriction on the SX-Es - it is NOT the same turbine and both looking at the designs, and also the results we've had so far... the SX-E turbine wheel happily flows significantly more than the S360SX one. The wheels are EXACTLY the same size, fit the same turbine housing etc but the aero is very clearly different and adds something to consider in regards to your postulating on the Borg Warner turbine sizes compared to Precision etc. The aero etc mean two different identical sized wheels can behave fairly differently.

- We actually hit the dyno yesterday with the RB30 after upgrading from the .91 S360SX to the .91 (literally the same exhaust housing from the S360SX put onto the S362SX-E) yesterday and unfortunately I can't share as much data as I would like to on the performance of the turbo as we ran into fuel delivery issues when we started turning it up on E85. We stopped at 20psi (just decided that was a good place to stop as we planned to push it harder on E85 as the car is flex) on pump gas (98RON) and saw 439kw @ hubs/588whp with power climbing happily to redline with zero difference to spool, followed the exact same boost curve of the old S360SX.

On E85 we got to about 22-23psi before running into fuel delivery issues so I never optimised the boost control, ignition timing or fuel curve because we didn't want to risk hurting the engine but with a soft tune on the first pull at that level it put down 489kw/655hp @ hubs and was showing no signs at all of hitting any flow limitations at that point. Power was carrying to redline at this boost level, as opposed to the S360SX (again, running the exact same exhaust housing) flat lined from 5500rpm to 7000rpm when targetting the same boost, it basically rolled back to 19/20psi at redline because it just didn't really have any more to give.

Gutted we didn't get to turn it up all the way, but it seemed on track to get to 700whp or more- we're very happy with the results so far - even if this was the finishing point it was a very worthwhile upgrade over the S360SX. Buying a turbo this cheap and gaining this much flow with no cost to response was great, again we had discussed the S364.5SXE but the response and delivery of the 61.4mm compressor would be a hard thing to want to give up for what probably wouldn't turn out to be a hugely rewarding increase in power.

Fun fact - we were hitting 300kw/400hp @ hubs at 3800rpm.
 

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Firstly, me and raamo both were running the S360SX which has an old pretty average flowing 60mm cast wheel - so yes, we did hit choke at around 19psi but that's not due to the a/r of the exhaust housing - it's due to the compressor wheel running out of flow so you do start seeing symptoms of high exhaust manifold pressure as well, but that's more to do with the turbine having to try and work harder due to the compressor becoming seriously inefficient and needing to be spun harder to move any more air. The fact that the S360SX turbine wheel is also not great for flow relatively speaking is going to be a compounding factor (more on that shortly), but the main issue is the compressor flow imho.



Science!



When we were choosing options for the RB30 we considered the S364.5SX-E but we wanted as much response as possible, seeing as it looks like people may not have analysed stuff as much as I did I might add some data which could prove helpful.

- The S364SX-E looks at a glance to flow a lot better than the S362SX-E but the real flow gains are mostly had at over pressure ratio 3.0, which doesn't seem helpful for an pump gas 3litre engine. If you look at the 2.2-2.6 pressure ratio range you're likely to operate in then the S364 may still at a glance look like it has big advantages but actually Borg Warner have mapped the S364SXE compressor map down to 54% compressor efficiency, which is pretty much useless. Anything under 60% efficiency is going to be generating a fair bit of heat and even if your intercooler is up to it - you're going to be needing increasing turbine energy to drive that compressor, which is going to drive up EMAP. For this reason I try and compare compressor maps "efficiency for efficiency", at which point the 64.5mm inducer/87mm exducer compressor has only 5lb/min more effectively flow most of the useful map than the 61.4mm/83mm compressor wheel. Maybe 6% more flow for a significantly larger compressor wheel, definitely larger by enough that you will loose spool and also at reasonable cost to transient response

- The "Use the same turbine wheel as the S360 and S362 to get the same response", going by this comment and other comments in here - thought I'd add that the S360SX and the S362SX-E use different turbine wheels. With our testing so far we've found basically no difference in spool between the two, but just to avoid any anecdotal evidence of how the S360SX turbine performed being used to determine a possible restriction on the SX-Es - it is NOT the same turbine and both looking at the designs, and also the results we've had so far... the SX-E turbine wheel happily flows significantly more than the S360SX one. The wheels are EXACTLY the same size, fit the same turbine housing etc but the aero is very clearly different and adds something to consider in regards to your postulating on the Borg Warner turbine sizes compared to Precision etc. The aero etc mean two different identical sized wheels can behave fairly differently.

- We actually hit the dyno yesterday with the RB30 after upgrading from the .91 S360SX to the .91 (literally the same exhaust housing from the S360SX put onto the S362SX-E) yesterday and unfortunately I can't share as much data as I would like to on the performance of the turbo as we ran into fuel delivery issues when we started turning it up on E85. We stopped at 20psi (just decided that was a good place to stop as we planned to push it harder on E85 as the car is flex) on pump gas (98RON) and saw 439kw @ hubs/588whp with power climbing happily to redline with zero difference to spool, followed the exact same boost curve of the old S360SX.

On E85 we got to about 22-23psi before running into fuel delivery issues so I never optimised the boost control, ignition timing or fuel curve because we didn't want to risk hurting the engine but with a soft tune on the first pull at that level it put down 489kw/655hp @ hubs and was showing no signs at all of hitting any flow limitations at that point. Power was carrying to redline at this boost level, as opposed to the S360SX (again, running the exact same exhaust housing) flat lined from 5500rpm to 7000rpm when targetting the same boost, it basically rolled back to 19/20psi at redline because it just didn't really have any more to give.

Gutted we didn't get to turn it up all the way, but it seemed on track to get to 700whp or more- we're very happy with the results so far - even if this was the finishing point it was a very worthwhile upgrade over the S360SX. Buying a turbo this cheap and gaining this much flow with no cost to response was great, again we had discussed the S364.5SXE but the response and delivery of the 61.4mm compressor would be a hard thing to want to give up for what probably wouldn't turn out to be a hugely rewarding increase in power.

Fun fact - we were hitting 300kw/400hp @ hubs at 3800rpm.
Lith, thanks for sharing your data from the RB30, that's really helpful. Awesome to see 588 on pump gas with the 362 which does reinforce that this could be the best response setup for my goals of 550-600whp.

I hear you 100% on the fact that wheel dimensions and design create totally different flow characteristics, and are two completely different variables.

Looking at AGP Turbo the efficiency in the compressor maps looks better the 5-6% - more like 5-10% in the 2.2-2.6 PR range at higher flow rates.

Speaking only of the S300 SXEs, 362 and 364.5 specifically, the added inertia of the the 3.9mm larger compressor reducer on the 264.5 is going to be quite minimal (speculation) when compared to the mass of the total rotating assembly of the 362sxe. The total difference between 362 and 364.5 as they share shaft, turbine wheel & bearing system is the added compressor wheel mass in the 364.5. This is all speculation as I don't have total rotating assembly mass on hand for the 362sxe and compressor wheel masses. I am cautious to get the 362sxe as I would hate to come up short by that ~5-10% on my power goal. This would be interesting to test.
 

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Also, I'm only considering the SXE - so I don't doubt that you ran out of compressor wheel on the old 360SX design. When I refer to choke - I'm thinking of the hot side creating a restriction that chokes off output.

Looks like I'm back to bouncing between the 362SXE and 364.5 SXE, but am leaning more 364.5 SXE to ensure that I hit my power goals, perhaps a the expense of a little bit of spool transient response. I certainly do not want to bump up to the 366SXE and associated larger turbine.
 

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Lith, thanks for sharing your data from the RB30, that's really helpful. Awesome to see 588 on pump gas with the 362 which does reinforce that this could be the best response setup for my goals of 550-600whp.
No worries. Again, this was not all in - we decided to stop at 20psi as thats a nice easy place on pump gas, and we put the higher power efforts into E85. Basically on pump gas its a fun road car, and if you get it drunk then it dials up the boost in the higher gears and harnesses the extra flow potential.


Looking at AGP Turbo the efficiency in the compressor maps looks better the 5-6% - more like 5-10% in the 2.2-2.6 PR range at higher flow rates.
You sure? Again to compare them properly you need to ensure the compressor efficiency is equal at the point you do the comparison, saying the S364SX-E goes to 80lb/min when its doing that at say 54% efficiency when the S362SX-E does "only" 76 but at 60% means you are comparing where the S364 is working much much harder. Here's the 61.4, 62.9 and 64.5mm compressor maps pointing out where 64% efficiency (where you usually start getting degrading performance as you go beyond) falls at PR 2.6:

S362SX-E at 71lb/min:


246034



S363SX-E at 71lb/min:

246035


S364SX-E at 75lb/min:

246036


So yeah, the 61.4 and 62.9mm are virtually identical efficiency at equivalent flow at PR2.6, the 64.5mm moves 5.6% more air at the same efficiency.



Speaking only of the S300 SXEs, 362 and 364.5 specifically, the added inertia of the the 3.9mm larger compressor reducer on the 264.5 is going to be quite minimal (speculation) when compared to the mass of the total rotating assembly of the 362sxe. The total difference between 362 and 364.5 as they share shaft, turbine wheel & bearing system is the added compressor wheel mass in the 364.5. This is all speculation as I don't have total rotating assembly mass on hand for the 362sxe and compressor wheel masses. I am cautious to get the 362sxe as I would hate to come up short by that ~5-10% on my power goal. This would be interesting to test.
Doesn't take much to add lag. That diesel testing you have already watched shows very clearly the advantage the 61.4mm has over the other two turbines and that doesn't even factor moment of inertia which is heavily reliant on the furthest mass from centre. Its well known it only takes a couple mm to make a noticable difference to response but I understand not wanting to fall short of your target - just giving you info to help you be in the best position to make an informed choice, we like different things and I'm sure it would be fine one way or another. I'd be interested to see how you get on with something a bit different, more results to compare :)

Also, I'm only considering the SXE - so I don't doubt that you ran out of compressor wheel on the old 360SX design. When I refer to choke - I'm thinking of the hot side creating a restriction that chokes off output.
Yeah I know, I understand that - what I was referring to is that the compressor can be responsible for the turbine causing choke early too. As compressor efficiency starts falling away (look back at the horrifically low 54% they've mapped the S364SXE to) the turbine needs a lot more energy to try and increase mass flow, which means the gate needs to close more to maintain boost, which means exhaust manifold back pressure goes up. The 0.91a/r 76mm hotside is more than sufficient imho, at least if the engine is up to it and I guess some dynos read different which can be a factor too. I've already proven an "easy" 580hp on a hub dyno.

Whatever you do, please update - we obviously considered the 63mm and 64.5mm options too but are very happy with where we have settled... it spools awesome and still has headroom.
 

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No worries. Again, this was not all in - we decided to stop at 20psi as thats a nice easy place on pump gas, and we put the higher power efforts into E85. Basically on pump gas its a fun road car, and if you get it drunk then it dials up the boost in the higher gears and harnesses the extra flow potential.




You sure? Again to compare them properly you need to ensure the compressor efficiency is equal at the point you do the comparison, saying the S364SX-E goes to 80lb/min when its doing that at say 54% efficiency when the S362SX-E does "only" 76 but at 60% means you are comparing where the S364 is working much much harder. Here's the 61.4, 62.9 and 64.5mm compressor maps pointing out where 64% efficiency (where you usually start getting degrading performance as you go beyond) falls at PR 2.6:

S362SX-E at 71lb/min:


View attachment 246034


S363SX-E at 71lb/min:

View attachment 246035

S364SX-E at 75lb/min:

View attachment 246036

So yeah, the 61.4 and 62.9mm are virtually identical efficiency at equivalent flow at PR2.6, the 64.5mm moves 5.6% more air at the same efficiency.





Doesn't take much to add lag. That diesel testing you have already watched shows very clearly the advantage the 61.4mm has over the other two turbines and that doesn't even factor moment of inertia which is heavily reliant on the furthest mass from centre. Its well known it only takes a couple mm to make a noticable difference to response but I understand not wanting to fall short of your target - just giving you info to help you be in the best position to make an informed choice, we like different things and I'm sure it would be fine one way or another. I'd be interested to see how you get on with something a bit different, more results to compare :)



Yeah I know, I understand that - what I was referring to is that the compressor can be responsible for the turbine causing choke early too. As compressor efficiency starts falling away (look back at the horrifically low 54% they've mapped the S364SXE to) the turbine needs a lot more energy to try and increase mass flow, which means the gate needs to close more to maintain boost, which means exhaust manifold back pressure goes up. The 0.91a/r 76mm hotside is more than sufficient imho, at least if the engine is up to it and I guess some dynos read different which can be a factor too. I've already proven an "easy" 580hp on a hub dyno.

Whatever you do, please update - we obviously considered the 63mm and 64.5mm options too but are very happy with where we have settled... it spools awesome and still has headroom.
100%, and I see what you're saying about comparing maps efficiency for efficiency - looks more like a 4-6% benefit as you pointed out.

I ordered the s364.5 SXE on Black Friday sale from AGP with a 0.68AR T4 hot side - this is due to octane limitations here preventing me from running E85 and higher boost. If I want more power down the line I will have to retune once better fuel becomes readily available, or I get a meth kit, in which case I will increase turbine housing side and retune as needed. For now the 0.68 hot side on pump gas should be the best fit for pump gas boost values and maximizing response.

Looking forward to my next tuning day, but it may not be for a while as I am working on my 6R80 swap also at the moment. Might be more economical to hold of putting in the new turbo and tuning once the new trans is in as the engine loading etc. will likely be slightly different and minor fuel tune adjustments will be needed.
 

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I ordered the s364.5 SXE on Black Friday sale from AGP with a 0.68AR T4 hot side - this is due to octane limitations here preventing me from running E85 and higher boost. If I want more power down the line I will have to retune once better fuel becomes readily available, or I get a meth kit, in which case I will increase turbine housing side and retune as needed. For now the 0.68 hot side on pump gas should be the best fit for pump gas boost values and maximizing response.
What kind of power are you shooting for on pump gas? It's not the route I would have gone for best fit for pump gas BUT on that note, I am particularly interested because we can all be wrong sometimes - very very interested to see what the "opposite" route to how I would have done it goes. I'd have concerns about the .68a/r hotside causing octane limit issues, unless you are going to be really soft on it but it may well also offset some of the lag from the bigger wheel too. I'm quite curious to see how it goes :)

Please update whenever you get around to it!
 

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What kind of power are you shooting for on pump gas? It's not the route I would have gone for best fit for pump gas BUT on that note, I am particularly interested because we can all be wrong sometimes - very very interested to see what the "opposite" route to how I would have done it goes. I'd have concerns about the .68a/r hotside causing octane limit issues, unless you are going to be really soft on it but it may well also offset some of the lag from the bigger wheel too. I'm quite curious to see how it goes :)

Please update whenever you get around to it!
Likewise, I'm running an HE351CW currently - 60mm compressor, tiny T3 0.65AR hot side. 430WHP at 17lbs. 300ftlbs torque at 3100RPM, definitely an atypical turbo setup.

Shooting for 550-600 on pump, will be going through the 6R80 which should translate more of that power to the ground than the A340. I doubt the 0.68 will come into play limiting power in a significant way. If it does, I can swap up to a bigger housing. I couldn't justify the added expense of a 6466 for similar power goals, the Borgs offer a lot of value.
 
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