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Thrasher. Any turbo with a very high speed range and small compressor inducer size, will have a extremely high vacuum that builds up in the chamber just before the compressor wheel. Added to the turbines exducer axial load, this significantly increases the over all axial load (towards the compressor side) which in turn causes the spacer as well as the thrust washer to wear out quickly. But I would be much more worried about any turbo with compressor surge and high speeds breaking shafts long before that. This has been a major contributor with any turbo for the last 30+ years, even at low/medium speeds.
 

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Sydoforumsuperfan :)
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Discussion Starter #563
Tech in your opinion what is the ideal turbo for TD42 ?
 

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Hi Sydo, I did read it the first time and chose not to reply. As it's all relative. There's some great turbos out there. But there's also a massive difference between reliability, drivability and dyno sheets. And prioritised in that order. The ideal (perfect in every way) hasn't been invented yet IMHO.
 

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Sydoforumsuperfan :)
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Discussion Starter #566
Hi Sydo, I did read it the first time and chose not to reply. As it's all relative. There's some great turbos out there. But there's also a massive difference between reliability, drivability and dyno sheets. And prioritised in that order. The ideal (perfect in every way) hasn't been invented yet IMHO.
You would run a ??
 

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In OZ we call this ducking and diving :D
Not in the slightest. But what I really can't be bothered doing is giving you turbo models for you to try and argue pointless dyno results against. When the fact is. A turbo with the attributes described, its not a matter of if its going to fail, only when. So comparing it is utterly pointless. If you have had no problems in 5 years, as you claim. And I don't know you, and have no reason to doubt you (other than favoritism). Then you are not getting anywhere near the performance, or you need to go and buy a lotto ticket.
 

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Sydoforumsuperfan :)
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Discussion Starter #572 (Edited)
Not in the slightest. But what I really can't be bothered doing is giving you turbo models for you to try and argue pointless dyno results against. When the fact is. A turbo with the attributes described, its not a matter of if its going to fail, only when. So comparing it is utterly pointless. If you have had no problems in 5 years, as you claim. And I don't know you, and have no reason to doubt you (other than favoritism). Then you are not getting anywhere near the performance, or you need to go and buy a lotto ticket.
Oh come on. I've seen a couple you don't like now tell us what your preference is. Positivity goes a long way. I'm sure others would be interested in your opinion. Would like to hear about your expertise on the flip side
 

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So this.

How is something you are saying is so bad (the GTurbo), so good.

High drive ratio means high losses right? So if the drive ratios are as bad as you say, why isn’t the GTurbo losing in the mid to top end of the rpm range?

So my point is, as far as performance and economy is concerned (the very reason we all fit turbochargers), you can’t have it both ways; either the turbo is technically better for the application and the result is demonstrable in a dyno test or it is worse.

Has been a revolving question that I’ve answered many times before. As Oldmav has mentioned in another post, and people are just starting to understand it. Firstly, I don’t really care if this guy gets it or not, I’m not here for that. If you have to ask these questions in the first place – then you don’t.

Turbine back pressure is an important factor in any turbo-engine development. A 1.4:1 emp:imp ratio is the point at which a 42mm valve can start to be over powered. I’ve tested enough turbos displaying these type of characteristics before, and already know that on this turbo the boost pressure would have been diving hard after peak boost pressure was achieved during development (can’t really call it development, more like testing) as the turbine back pressure would be driving it down (where pressure increases, flow reduces). At that point, instead of fixing the turbine back pressure issue (larger wastegate hole, runner length, angled runner, correct length actuator arm, correct size diaphragm, pre-load and spring rates etc). There’s an oversized arm restricting movement that only compounds the issues driving the turbine back pressure up even higher with the intended result for the compressor mass flow to overcome the turbine back pressure/ VE in order to make “some” gains. This seems to be the theme for all these turbos. Engineered turbo diesel performance – my ass. More like BS marketing.

Boost pressure means nothing, and is only relative to the turbine pressure (Boost pressure = power, Compressor mass flow = torque). If you have to run very high boost pressure to achieve goals, then it's a badly chosen turbo. There is far more to it than a simple dyno sheet. If the turbine back pressure was reduced to “safe” levels the torque would go through the roof – for less fuel and less shaft speed. I used the word “safe” because turbine back pressure increases egts = Egts are not an issue at all with the correct PR on application developed turbos which allows it to run more fuel (with half the boost pressure, it would destroy most others, yet look less on paper). In this case the pre-load on the actuator arm allows it to open slightly until it hits a dead stop, this dead stop might be this turbo’s only saving grace. If it was on spring pressure only and ever hit waste gate bounce, the torsional loads would snap the shaft in a second (been there, done that) and every turbo would fail.

This set up isn’t anything new I haven’t seen many times before, mostly from people trying to get high performance from turbos that are far too small. The difference here is just BS marketing and claims, that people believe and repeat, defending something that’s undeniable. So being asked what’s a good turbo – there is no easy answer. Mumbais and kawabungas are just lower quality mix and matched copies, with zero engineering or consideration. Yes, the borgwarner is good, but again based on petrol flow charts and not the needs of a turbo diesels.
 

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Cool story, so what should we be buying? (Fyi i dont have a gturbo)
 

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So what Turbo would the @Technician recommend for a TD42T with an 11mm pump, 3 inch exhaust, 4 inch snorkel, decent airbox and a 600x300 intercooler?

Aiming for around 150rwkw at most
 

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Is that code for i dont know?
 

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Just about any turbo you buy, you will have to test and modify until its right for your engine.
I would rather buy one that has all the research and development done rather than do the testing myself. You seem to make a point about GTurbo not being developed properly, so what turbo would best suit my vehicle, (with the list of mods above) that will need the least amount of modifications? Surely there must be at least one supplier that has something close to what I want out of the box?
 

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