Replace the G30 770 or upgrade g35 900

[Russdmuss]

Hi Guys, 

Just wanting to replace my current turbo (pulsar g30-770)which has catastrophically failed,  I believe it was from over-speeding but can't confirm that. 

The car 

S13 with rb25 neo with Tomei procams type b, rod bolts, metal headgasket, plasmaman plenum, standard exhuast manifold with external gate welded on and pulsar g30 770 .83 housing. 

Car made 591hp at the hubs on just over 26pd

The purpose of the car is some street driving but does a lot of circuit racing and tarmac events. 

The car is great to drive super responsive on the street and track, as the engine is getting built as we speak and the turbo has failed I want to replace it with a garrett unit and a 6 boost manifold. 

Question is would a twin scroll g35-900 1.06 be as responsive? Or do I stay with a g30-770 and move up to a larger rear housing. 

Yes I know it's been covered in other sections but haven't found and real back to back information. 

Thanks Russell 

[r32-25t]

At 600 at the wheels there’s a good chance you’re pushing the turbo to or beyond its limit. A good option might even be use a  g30 900 to make the same power you already are 

[Lithium]

10 hours ago, Russdmuss said:

Question is would a twin scroll g35-900 1.06 be as responsive? Or do I stay with a g30-770 and move up to a larger rear housing. 

Seeing as it's a little ambiguous as to why you might be upgrading, I'll give some bullet point answers based off the two reasons you may be:

Upgrading because you're assuming the failure is overspeeding:

1. A G30 770, either Garrett or Pulsar version should not be overspeeding at this power level.  It's leaning on them a little but should still be in a relatively safe place
2. Any details on how the turbo looked/what broke and when?  First time I've heard of a catastrophic failure with a Pulsar, can never rule out a manufacture issue with them (I know people who've had this with Garrett, Borg, Precision etc so Pulsar probably won't be immune)
3. You can also overspeed the turbo without actually trying to make more power than it can support, if you have a restrictive intake or intercooler, or some kind of boost leak then there is the possibility that either the turbo is seeing a much higher pressure ratio than you'd guess based off when you see at the intake manifold - or alternately the turbo could be moving a heap more air than the engine is seeing, both causing it to overspeed while actually giving the engine less air than the turbo can provide if everything is working efficiently.  
4. Make sure there is no other issue with your setup that could possibly cause a premature failure, like oil feed blockage or something to that effect

^ Especially #3 and #4, make a seriously good effort in ruling out or identifying any possible cause there because you don't want to spend >2x the cost on a replacement turbo to end up with the exact same thing happening.

Upgrading because you're levelling up:

1. How much more power are you after?   If you're happy with the power and response you had already, 590hp @ hubs isn't a heap short of what the compressor supports with those so going up an a/r may result in an underwhelming increase in power vs how much extra lag you get from it - imho the .83 seems like a good balance on the 770 even if it may hold it back a little at the top end of it's capabilities.  
2. Check out the 6466/G35 900 thread, someone has gone a 1.06a/r T4 Garrett G35 900 on their VCam RB28 and it's a lot laggier than this.   There's no magic, if you have a bigger compressor, bigger exhaust wheel, big tubular manifold and larger exhaust housing then twin scroll is not going to offset the response at all.... but it will be capable of an extra 100kw @ wheels safely.
3. If you are after an incremental increase maybe consider the 1.01 T3 G30 900, or if they have it a 1.06 T4 G30 900 - I'd wager that has a good chance of being a sensible in-between if you are concerned about response.  It's unlikely that you'll be able to go up in power potential without some cost to response but that is one way that's likely to manage the impact somewhat.

 

Just my thoughts. 

[Lithium]

Argh also, I missed a point above - it seems that especially with the Pulsar turbos third party dealers seem to sometimes mess up orders.   I've seen it (not directly experienced it, but definitely seen it happen to other people) where someone will order something like a GTX3584RS and end up with a GTX3582R, or a "G30-770" turns out to be a GTX3071R etc.  If you had a GTX3071R or even GTX3076R or G30 660 and tried to run it like a G30 770 then there could easily be carnage.   I've seen people run near 600hp @ hubs on the Pulsar G30 660 on ethanol so it can be done, but probably not super wise.

[Russdmuss]

Thanks for the detailed reply Lithium

Okay first thing, I'll find some photos of the turbo failure. The night it failed we were at the drags and it was on the fourth pass of the night and it does have traction control which was on during the passes but only active in 1st and 2nd gear. 

The front wheel has made contact with the hosuing and snapped the shaft sending debris through the cooler and into the engine. 

One weird thing I did notice just before it failed was the intake temp in the airbox went higher then it ever has by 15 degrees (peaked 65c).

Oil line is clean and seems to flow normal I checked that once the turbo was removed.

The only reason I was going to go a bigger frame turbo was I was concerned it was overspeeding and failing again and I'm sure one day I'll want to turn it up some more.

 

The g30 770 was great on the street and circuit, I will fit a speed sensor this time. 

[r32-25t]

I’d be throwing the intercooler in the bin, it’ll have shit all through it 

[Russdmuss]

I did try to plot a turbo map of g30 770 using match bot but it was my first go at using it and I could be way out on this.  It seemed to be out of the map by a large amount at 8500rpm with 26pd

[Lithium]

12 hours ago, Russdmuss said:

I did try to plot a turbo map of g30 770 using match bot but it was my first go at using it and I could be way out on this.  It seemed to be out of the map by a large amount at 8500rpm with 26pd

Ohh.   I may have made a bad assumption with my previous post - I kinda glanced at the power and assumed your were running ethanol (which kinda assumes a certain airflow vs power conversion) which would make that power seem perfectly within the G30 770 capacity but actually, looking at the rpm and boost you're right... all things being "typical" your engine is likely to be breathing a heap more than that turbo would want to give at that boost.

What fuel are you running on?   

[Russdmuss]

Sorry should of mentioned that e85. 

[Lithium]

Ugh actually.  Please hold, I'll just actually run the math properly and see where you're likely to actually be instead of guessing.  Bbs

 

[Lithium]

This is what I get when I have a quick go at Matchbot, let me know if it seems like I'm missing something. I'm "only" running it to about 7700rpm though as that's all your dyno plot goes to.  Plausible that running it to 8500 could go further but it looks like your VE is going to start plummetting after 7700rpm so I'd not necessarily expect the compressor to need to do heaps more.

What ECU are you running?  You could look at logs to get a gauge of the estimated airflow.  Here's my attempt at matchbot: https://www.borgwarner.com/go/N0YW5D

 

 

[Russdmuss]

Thankyou for doing that. A lot different to what I plotted but again I'm very new at this. 

Looks like there is still a bit of head room in that turbo, or am I looking at this incorrectly? 

It's running a motec m130 gprp.

[Lithium]

21 hours ago, Russdmuss said:

Thankyou for doing that. A lot different to what I plotted but again I'm very new at this. 

Looks like there is still a bit of head room in that turbo, or am I looking at this incorrectly? 

It's running a motec m130 gprp.

Ah sorry, from some things you'd mentioned I assumed you were more comfortable with reading compressor maps.   Nah, you're right against the edge. The red line I've drawn through the map is a rough estimate of where your engine may be operating in and it "stops" basically just at the max-rpm line on the right side of the compressor map.   Touching that line doesn't mean instant fail by any means, but it does assume there are no outside factors meaning it has to spin harder and obviously I'm also just taking a punt so there is no guarantee that's accurate.  
 

Nice computer   Maybe not necessarily quite a straightforward to work out the airflow the ECU reckons the engine/turbo are moving though it's definitely capable with I2 etc.  

[Russdmuss]

Im Slowly learning Lithium. 

At this stage I'm leaning towards replacing it with another g30 770 and fitting a speed sensor/possible a EMAP will its apart. Once it's back together I'll get some data and post it up. 

The ecu is fully unlocked so I will see if I can work it out. 

[Lithium]

16 minutes ago, Russdmuss said:

Im Slowly learning Lithium. 

Same. 

Do you have I2/I2 Pro?  How familiar with the software are you?

[Russdmuss]

I2 Pro, I used it every time I take to circuit racing so a very basic understanding. 

[Komdotkom]

23 hours ago, Russdmuss said:

Thankyou for doing that. A lot different to what I plotted but again I'm very new at this. 

Looks like there is still a bit of head room in that turbo, or am I looking at this incorrectly? 

It's running a motec m130 gprp.

When you say GPRP is that GPR+paddle shift or GPR+Pro? There's some pretty nifty stuff you can do with Pro which may be of some use to you but I'm in the process of setting it up on mine at the moment so don't have a super deep understanding of the torque model at the moment.

 

Edited October 18, 2023 by Komdotkom

[Lithium]

Haven't used the GPRP just something just occurred to me if you're using a package which supports torque management - I tuned an R35 using the M1 GTR package and one of the things that quickly got my heckles up was seeing the throttle pressure ratio data when trying to manage torque etc.   

Some competition level (Emtron as well) engine management systems that do stuff like this to ensure that you can control power delivery carefully but also have the turbo speed maintained so that when you want the torque "back again" without waiting for the turbo to respool can actually put a massive amount of load on the turbo if you're using e-throttle as part of the torque management.   Like, huge pressure ratios and turbine speed - I'm not saying this is a thing with yours but its a thing that just popped into my head when @Komdotkom , mentioned "nifty stuff".    If you are using e-throttle and torque management it's very much a thing to bare in mind, the conventional turbo matching stuff goes straight out the window when you start doing stuff like that as the transient situations can potentially end up operating the turbo in really strange places.

Strictly speaking that can even be a thing if you go half throttle with a conventional throttle where the turbo is still targetting "full boost" and the boost control setup is able to maintain close to target, the turbo has to try and make up for the pressure ratio across the throttle as well and can end up working super hard - this is actually another reason why it can be sensible to reduce boost targets at part throttle.  A small hint of this phenom is where some cars can go into surge conditions at part throttle.  Pressure ratios vs flow get super odd.

Edited October 18, 2023 by Lithium

[Russdmuss]

34 minutes ago, Komdotkom said:

When you say GPRP is that GPR+paddle shift or GPR+Pro? There's some pretty nifty stuff you can do with Pro which may be of some use to you but I'm in the process of setting it up on mine at the moment so don't have a super deep understanding of the torque model at the moment.

 

It is GPR + paddle shift. 

 

Good point lithium, I noticed when using the traction control the boost would spike quickly during Cut events when looking at the data. Might be worth monitoring it against a speed sensor. 

[Komdotkom]

To the best of my knowledge GPR doesn't do torque management so you don't have to worry about that aspect of it. I haven't tried but you should be able to build a table for turbine speed vs WG position or DC to prevent future explosions.

Would you go with another PSR or genuine this time?

A mate runs a 40mm DBW TB to atmosphere as a boost bleed pre TB and fresh air anti lag. This results in wild turbine speeds and response. And broken turbos!