- Over the last few years we've seen a huge improvement
in the availability and performance of performance
aftermarket turbochargers.
And we're here with Harut from Turbo by Garrett
to talk about Garrett's new range of G series turbochargers.
Now we haven't seen a real big advance in turbo
technology with the Garrett range for some time
and this G series turbocharger
really has been a clean sheet of paper, a redesign.
So let's talk through the design aspects that have gone
into that turbocharger.
Where did you actually start?
What's the most critical part when you're designing
a turbo with a clean sheet of paper.
- Right so I mean we started off with a GTX Gen 2 last year.
We did a compressor wheel and compressor housing upgrade.
So that was a nice step towards better performance.
We increased flow anywhere from 5% to 10%
with the Gen 2.
So now with the G series it was a complete clean sheet
as you mentioned.
We took feedback from all of our customers
and internally with our engineers
and we came up with this design.
So we started off with the centre housing,
the centre housing is two piston rings on each side.
We have an oil deflector on the compressor side
so that it has better oil sealing capability.
We did oil fittings, water fittings,
so that oil restrictor is now integrated to the turbocharger
comes with the fitting.
We have dual water ports on each side,
so that gives you the flexibility with the water lines.
- Can we just go back to the oil side of things there.
So first of all you mentioned the restrictor.
And I know this is a problem a few people have
with various turbo installations is getting the correct
oil supply to the turbocharger.
You're not over oiling the turbo and hence
risking that leakage either into the compressor
or the exhaust side.
And with the ball bearing turbochargers as well,
they don't actually require a huge volume of oil flow?
- Right exactly so we recommend usually like 40, 45 psi.
And we provide a one millimetre restrictor
included in the fitting.
So that should suffice with most of the engines out there
and reduced oil pressure.
'Cause typical engine oil pressures are anywhere
from 60 psi and up so you wanna reduce that.
'Cause yeah the ball bearing cartridge
doesn't require that much oil.
- Now in terms of those seals then,
so these are really, between the seals and you also
mentioned the deflector behind the compressor wheel,
so these are really sort of a safety backstop
if we do end up with some oil leakage,
this is going to help reduce that?
- Yeah exactly so we had single piston rings before
so now we improved to dual piston rings on each side.
And that oil deflector technology we took from
our OE side, we've learned a lot from there,
and that should help with the sealing capability
and reducing smoke coming onto the turbine stage
or the compressor stage.
- Now in terms of that water cooling,
we've seen turbochargers incorporate water cooling
for a long time.
I know that in the performance aftermarket,
a lot of installations where turbochargers
do have water cooling,
the people in charge of the installation haven't used it.
Just interested, how vital is that water cooling
for reliability and durability of the turbo?
- Yeah I mean especially if you're running higher
temperatures, higher * temperatures,
we always recommend a water cooling.
But like you said people have run without it
with no issues so our turbochargers are meant
for reliability and durability.
- Would it be safe to say maybe for short duration
running like a drag application maybe that it's less
critical than perhaps endurance or circuit racing?
- Right exactly and so when you have the contsant
high temperature then that might become an issue
'cause that temperature will eventually make its way
to the bearing and you can probably
have some bearing damage.
- OK so moving onto the compressor wheel,
obviously really the key to moving air
into the engine and again with a clean sheet of paper,
design in front of you,
what did you do with that compressor wheel
and why are we seeing the performance improvement
from it?
- Yeah so it's all new, new compressor wheel,
new blade shape technology that's run through
CFD and FEA.
So that's what gives it the high flowing compressor
stage along with the increased AR on the compressor housing.
- OK so in terms of the design of that compressor wheel
as well, it is billet and I think there's a misconception
or a misunderstanding out there in the greater industry
that the billet compressor wheels have really
been responsible for a huge improvement
in performance.
So what can you tell us about that?
How accurate is that?
- Not very accurate.
The biggest jump going from cast to billet
is the ability of it, the fatigue factor.
So with the forged wheels you have higher
life cycle account compared to a cast wheel.
In terms of performance there's not much difference
between a cast and a forged wheel.
- So essentially once you've got a billet wheel,
a forged wheel designed, you're happy with that design,
you could potentially remanufacture that in a casting,
it's gonna offer the same actual air flow performance,
but it may be particularly at high pressure ratios,
the reliability of that wheel may not be so good?
- Right exactly.
And really aesthetics right, I mean you look at a cast wheel
and it looks grey, it looks dull,
but you look at a forged wheel for the machined wheel
and it's very nice and shiny.
- While we'd like to say that that's not important
when it comes to turbochargers,
we all know that how it looks does have an impact
on the purchase decision.
OK now also can you talk to us about the trim of that wheel
and how that's differed between the previous
Gen 2 turbochargers.
- Right so the trim actually attributes for the increased
flow as well.
So with the higher trim,
this compressor wheel's qualified to a higher trim
so we're able to increase the inducer diameter
compared to the previous generation's.
- Just for those who aren't aware,
the trim refers to the inducer diameter
versus the exducer diameter.
- That's correct yep.
- So as you move to a higher trim,
the compressor wheel simply can flow more air?
- Yes that's correct.
- And are there any downsides to increasing the trim
of the compressor wheel?
- Yeah you just have to make sure it's qualified
to the fatigue life that you expect it to survive
'cause the more you bring out the blades
then you have more resonance on the blades
so you just have to make sure that
it's gonna survive.
- OK so moving to the turbine side,
because this is the area really we haven't seen
a lot of change in the Garrett range
with their turbine wheels until now.
So again, clean sheet of paper, what's changed there?
- Right so in terms of the turbo wheel,
we did make an upgrade with our 35 80 4RS
starting last year.
So now we're taking another step beyond that
and we changed the material to MAR-M
which is capable up to 1900 degrees fahrenheit.
And that's a first in the aftermarket.
- So 1900 fahrenheit, how does that compare
to the temperature handling capability
of you previous turbine wheels?
- Right so before it was, we were at 1050 C,
or we we're at 1050 C now,
before it was about 850 C.
So we definitely improved the capability quite a bit.
And obviously new aerodynamics.
So it flows quite a bit more and it's at 74% efficiency.
- In terms of that efficiency, again how does that
compare back to your previous range.
- Yeah so before it was about 69%,
we jumped to 74% on a turbine side.
And then a compressor side,
now we're at 80% efficiency.
So with that overall efficiency the turbocharger
that helps with the spool up.
So you don't have to spin the turbo as much
to make the power with higher efficient turbos.
- In terms of that material that you've used
for the turbine wheel,
we've seen a lot of different material creep in
with different brands of turbocharger.
Some of them are lighter which is obviously aiding spool,
there's less inertia, there's a lower moment of inertia
in that product so it can spin and spool up quicker.
But of course the downside sometimes is
the reliability of those materials,
and strength of those materials at higher turbine speeds.
So how have you sort of balanced that and taken
into account the desire for a low moment of inertia?
- Right so with the MAR-M it is a denser wheel.
But we've done some deep scallops on the turbine wheel
in the back disk so that reduces the weight
and the inertia.
And obviously the efficiency accounts for any
increase in inertia.
- And also with the design of that turbine wheel,
for the size or the flow I should say really
of the turbocharger, the wheel diameters
are quite small compared to your previous range
so again that helps reduce the moment of inertia?
- Right exactly, it's a 54 millimetre turbine wheel.
And it is very comparable to our GT30 turbine wheels.
So basically you're getting that same amount of flow
in the small turbocharger compared to another
frame size up.
- So that's a great reference to move into.
So if someone's looking at one of the G series
turbochargers, you've got the G25-550
and the G25-660.
Those both rate to their flow horsepower capability,
550 and 660 horsepower.
So with one of those turbochargers,
let's take the 550 for example,
what would that compare to in the existing Garrett
range and what would the advantages look like
to the end user?
- Yeah so like G25-550 compares to our GTX3071 gen one.
If you compare it to that it's very similar
in terms of power capability.
But with running a 25 instead of a 30 you're gonna have
that really good boost response.
But be able to make that same amount of power.
- So same power, faster spool,
or alternatively I guess we could always
step up in the turbo size,
get a similar amount of spool to what we're already
been experiencing but with the ability for more power?
- Yeah that's exactly right.
- And I can only assume that we're expecting
more turbochargers to be added to that G series range
in time?
- Yeah so we're working towards the other sizes,
we're gonna proliferate into the other family sizes.
You know we'll do 30, 35, 42.
So keep an eye out for those next year.
- So with that you've just mentioned to GT42 sort of size.
What would you expect to be the maximum
power expectations with the largest G series turbo?
- Yeah we don't have that yet.
Once we do the design work and get that tested,
we'll have a better idea of where we are with the power.
But definitely it's gonna be increasing
by anywhere from 15% to 30%
just like we did on the G25.
- Well for us in the aftermarket using these turbochargers,
it's certainly an exciting time.
Anything that can provide more power
with improved spool, I'm all for.
If our viewers want to find our more about
these turbochargers, where can they head to?
- They go to turbobygarrett.com
- Thanks for the chat.
- Thank you.
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