thought standard boost was 1.9bar.......

 

Standard boost is around 24 psi settling at 20 which is around 1.6 bar. Don't know about remaped since mines is still standard.

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24 psi (1.66bar) on over boost but they settle at 22psi (1.52 bar) usually .
28psi is a hell of alot for a standard turbo and will be chewing through your thrust bearing.
52mm hybrids struggle to get 26psi above 4000rpm, so the standard 49mm will be superheating the boost charge at the pressures you are getting.

 

its been mapped or them boost figurs still too high

 

The only logged data I have is from a pootle around local roads to see if my sensors were working so I could mount my ipad in car, and the pressure ranges from -11psi to 12psi although I didn't get to push above 4krpm or about 40-50mph. Not knowing how turbos generally work, is a negative value something to worry about?

 

not on a petrol, you get a vacuum when the throttle valve closes hence the - value, so its completely normal.

 

So, what's the best way to record this? Is it the highest number the turbo achieves, or is there a figure at a certain RPM/speed I should be recording? Do I redline it? Just curious as to how I can get a figure to compare I have OBD monitoring software that logs stuff so I can drive and pick through the data later

 

What I done with mine using tourque app is stick it in third or 4th doing about 20-30 then plant it, that way you get the boost readings inc over boost from the whole rev range. But the 12-16 psi sounds about right for a petrol, std vxrs settle at only 17 psi with 20 psi on over boost, just to give you an idea.

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28psi on a standard GT1749MV is going to kill it.

 

I had a Zafira 19DT in work that was showing 290kpa :lol:

 

What are you reading 28psi on i calibrated my mechanical boost gauge at work and found it low a psi or 2 under 5psi and a 2-3 psi high in 25-30 psi.i watch boost gauge but dont base much on it go by map sensor.
Not sure what software you guys have but for boost issues id be logging actual boost, desired boost, vnt% and maf airflow.
With some data from a few logs you should be able to confirm operation of vnt mechanism and also boost leaks if maf rises but boost does not but id start by cleaning map sensor first and checking ign on if it reads same as atmospheric mb.
At 28psi id say either vnt not opening up fully and not lowering shaft speed enough, or mapped or boxed too high.
Is it decatted?
Over fuelling/late injection may also cause high egt boost creep etc.
If i kept my foot in i used to see +300mb over requested due to decat and green box causing creep and also high egt temps 750-850*c im sure if i kept my foot in longer it would have gone higher.upto point of going over desired boost i dont think it used to go much over 600*c
Ps isnt 28psi=more like 2900mbar and 27psi=2860mbar from map sensor at sea level?

 

max boost on mine was mapped in @ 1.8 bar iirc.. this with a 52 compressor in a 56 housing fyi lol

 

A 56mm cover from what turbo? It seems highly unlikely they stuck a 56mm comp wheel cover on a 52mm wheel as there would be a big gap between compressor and housing, resulting in poor performance. 1.8 bar (26psi) from a 52mm unit is quite acceptable.

 

cause the outside of the housing is stamped 2056 so that would mean a 56 compressor housing wouldnt it?

tis the whole reason i thought my hybrid was a 1756 till it was mapped lol

 

Yep i am mapped for 2850mb on a 55 trim 52mm wheel,about most i wanna go upto 4500.
To nutron
Have you still got any turbos in bits, if so can you measure up the turbine exducer and vnt vane heights and maybe a pic of the vnt ring layout?
My jtdm had a gta1749v with about 6mm vane height but ive heard a few refs to later gtb layout but never seen inside the mv.the earlier model had 5mm odd vane height, from the turbine spec is the mv nearer 7mm?
Thanks if you can, no probs if not possible.

 

i dont have any cats and have the down pipe mod with mine. had a greddy mechanical boost gauge that would show boost up to 1.9 bar another mechanical would show 1.9 bar as well. two different digital onea show 28 psi peak boost. ill have to connect in the diagnostic and take it for a blast and see what the actual boost sensor reads

 

Missing:
Does it say GT before the 2056? It should be a 56 cover if that is stamped on it but where did you get the turbo from? Did you get that mapped down at courtenays? Lots of questions

I have three hybrids in the garage and two standard units dismantled ready to hybrid, so I shall try to remember to measure the turbine tomorrow night.

 

erm i honestly cant remember, do deffo know it said 2056 on the side.. will be able to check if/when i buy a bigger hybrid next year!! Oh and you know where i went to get it mapped lols.. and the turbo was the 'big' t8 development turbo!

 

Yes, the one they gave up on because it did not give the results they wanted. They must have done something wronge somewhere as the smallest 56 I use, which is in a standard cover milled out has made 246bhp on mine. I think EDS had them made up in Germany.

The details I have in my logs suggests my turbine is

Inducer 43
Exducer 38
Tip height 7.2
Journal bearing 7.88
Compressor wheel bore 5.08
Straight shaft

I will have to check and measure the tip height.

 

How can you have inducer bigger than exducer.....

Missing didnt rs say you had a 52mm wheel in a 56 housing.....

Good result karl on courts 888

 

Ah yes, RS did the map, I'm getting old and I forget things. I am sure EDS had 52mm units made as I was following with much interest at the time.

The inducer on the turbine is always bigger as the inducer is the primary driver.

 

Clarfication

 

Clarify what? Look up some pictures of turbine and compressors in google.

The air flows into the compressor inducer, is accelerated down and compressed as it moves into the exducer, where it is further compressed and accelerated radially outwards into the cover plate and is slowed again to increase pressure.

The air flows into the turbine inducer at an angle and speed controlled but the VNT mechanisum. The air drives the turbine inducer like a water wheel and flows down into the exducer, where it acts more like a aerofoil.

 

Meaning you have already explained my questioning not that i wanted more clarification.

Thanks anyway shows that you understand a turbo.

 

Lol

Have to be clear about what you want

I did not get round to measuring last night as I was working until 21:30 but I will shortly

 

The dimensions from above seem to be right and the total height is about 21.5mm

 

those sizes seem identicle to my gta1749v, it would be nice to see a hybrid with the 43inducer 39.5mm exducer i put in my 52mm hybrid.but and big but i understand it would take a lot more work to machine your housing im guessing youd need a pretty good cnc miller or custom tool.
At least in mine i just shaped my own tool for lathe, opened up bore to 40.5mm and cut new profile to give same as original clearances on the new turbine(it was 8+mm tip height, so had to sit deeper also.also big but was turbine was over £100 on its own.
Id still like to see some vnt% on 220+hp with original turbine size.

 

I machined a turbine housing and made up a GT2556 from mine, it didn't spool until near on 3000rpm lol
The current trimmed turbine unit I have seems to be performing well and with a simular spool threshold, that would be easier.