New BW EFR Turbo Thread
Dec 1, 2011 | 03:22 AM
#1126
Newbie
Joined: Sep 2010
Posts: 14
Likes: 0
From: Australia
I've said it before and I'll say it again, a GT30 turbine wheel has LESS inertia than the EFR 70mm turbine wheel. You don't even have to do any funky math, just LOOK at the pic above and its obvious... Plus the GTX wheels have much more impressive compressor maps than their EFR equivalents. As for the claimed compressor/turbine mismatch, the GT30 turbine was originally designed for a 76mm compressor wheel, so it can't be all that bad, besides - where do all these so-called rules of thumb come from? An HTA86 is another highly mismatched turbo on paper, yet nobody can deny that its one of the best currently available turbos for a high-powered 4G63...
Had a HTA86 in my garage 13 months ago, sold it to buy a 9180. Still waiting with no firm information of when its coming. Little peeved I guess.
Dec 1, 2011 | 11:12 AM
#1130
I've said it before and I'll say it again, a GT30 turbine wheel has LESS inertia than the EFR 70mm turbine wheel. You don't even have to do any funky math, just LOOK at the pic above and its obvious... Plus the GTX wheels have much more impressive compressor maps than their EFR equivalents. As for the claimed compressor/turbine mismatch, the GT30 turbine was originally designed for a 76mm compressor wheel, so it can't be all that bad, besides - where do all these so-called rules of thumb come from? An HTA86 is another highly mismatched turbo on paper, yet nobody can deny that its one of the best currently available turbos for a high-powered 4G63...
Dec 1, 2011 | 12:11 PM
#1132
Newbie
Joined: Dec 2006
Posts: 76
Likes: 0
From: na
Let me walk you guys through this again...
GT30 turbine has 60mm inducer and 55mm exducer
7670 turbine has 69.5mm inducer and 61.5mm exducer
both of them have 10-blades
GT30 has a mean diameter of sqrt(55x60) = 57.44mm
7670 has a mean diameter of sqrt(69.5x61.5) = 65.38mm
rotational inertia = geometric constant depending on shape x m x R^2
m = another geometrical constant depending on shape x density x R^3
to sum up,
inertia = geometric constant depending on shape x density x R^5
in the real world, blade thickness does not go up directly with radius, and inertia is proportional to R^4.333 if the section is stiffness-limited, or R^4.666 if the section is strength-limited , which is probably the case here. Nevertheless, we will take the average of the two and use R^4.5 instead (which would work out in the 7670's favor)
density of inconel = 8.1
density of gamma-Ti = 4.0
assuming the geometric constants are the same,
I GT30 / I 7670 = (8.1 x 57.44^4.5)/(4.0 x 65.38^4.5)
I GT30 / I 7670 = 1.131
So a simplistic analysis shows that the GT30 turbine wheel has 13.1% more rotational inertia than the 7670, but this does not take into account the MUCH greater thickness of the 7670 blades, the superback section of the 7670 (which puts mass where it affects rotational inertia the most), and the longer/thicker nut section (which would have a minor effect on rotational inertia) The superback section ALONE has got to be worth more than the 13% difference between the two turbines, and we STILL haven't taken into account the thicker cross section of the gamma-Ti wheel!
The worst case scenario conclusion we can draw from the above is that the 7670 turbine wheel does NOT have a lower PMOI than the GT30, in fact its probably higher... The 7064 would have a significantly lower PMOI than the GT30 but then again it flows less given a similar housing... I hope I've made my point clearly
PS - I'm not passing judgement as to which of the above turbine wheels is "better", or more efficient, or faster spooling, just comparing their relative rotational inertias.
GT30 turbine has 60mm inducer and 55mm exducer
7670 turbine has 69.5mm inducer and 61.5mm exducer
both of them have 10-blades
GT30 has a mean diameter of sqrt(55x60) = 57.44mm
7670 has a mean diameter of sqrt(69.5x61.5) = 65.38mm
rotational inertia = geometric constant depending on shape x m x R^2
m = another geometrical constant depending on shape x density x R^3
to sum up,
inertia = geometric constant depending on shape x density x R^5
in the real world, blade thickness does not go up directly with radius, and inertia is proportional to R^4.333 if the section is stiffness-limited, or R^4.666 if the section is strength-limited , which is probably the case here. Nevertheless, we will take the average of the two and use R^4.5 instead (which would work out in the 7670's favor)
density of inconel = 8.1
density of gamma-Ti = 4.0
assuming the geometric constants are the same,
I GT30 / I 7670 = (8.1 x 57.44^4.5)/(4.0 x 65.38^4.5)
I GT30 / I 7670 = 1.131
So a simplistic analysis shows that the GT30 turbine wheel has 13.1% more rotational inertia than the 7670, but this does not take into account the MUCH greater thickness of the 7670 blades, the superback section of the 7670 (which puts mass where it affects rotational inertia the most), and the longer/thicker nut section (which would have a minor effect on rotational inertia) The superback section ALONE has got to be worth more than the 13% difference between the two turbines, and we STILL haven't taken into account the thicker cross section of the gamma-Ti wheel!
The worst case scenario conclusion we can draw from the above is that the 7670 turbine wheel does NOT have a lower PMOI than the GT30, in fact its probably higher... The 7064 would have a significantly lower PMOI than the GT30 but then again it flows less given a similar housing... I hope I've made my point clearly
PS - I'm not passing judgement as to which of the above turbine wheels is "better", or more efficient, or faster spooling, just comparing their relative rotational inertias.
Last edited by hydra; Dec 1, 2011 at 12:23 PM.
Dec 1, 2011 | 12:41 PM
#1134
I'd be surprised if anyone on these fourms are looking for that turbo....its too small for for most needs as its only good for 430ish HP.. most can extract close to that out of their stock turbos...
Dec 1, 2011 | 12:53 PM
#1135
Account Disabled
Joined: Oct 2011
Posts: 151
Likes: 0
edit: as an aside, Im planning to use the 8374 internal WG on my 2.0L evo, here is a dynochart from this twinscroll internal-WG turbo on a 2.0L k-series honda, 25 psi boost:
i realize most of you guys arent honda people, but this is easily the earliest spooling and strongest midrange of any 700+hp turbo weve ever seen on that engine and we sell a LOT of k-series turbokits to compare to..
i realize most of you guys arent honda people, but this is easily the earliest spooling and strongest midrange of any 700+hp turbo weve ever seen on that engine and we sell a LOT of k-series turbokits to compare to..
Knew i should have built a k20 instead
Dec 1, 2011 | 12:54 PM
#1136
Dec 1, 2011 | 01:02 PM
#1137
Let me walk you guys through this again...
GT30 turbine has 60mm inducer and 55mm exducer
7670 turbine has 69.5mm inducer and 61.5mm exducer
both of them have 10-blades
GT30 has a mean diameter of sqrt(55x60) = 57.44mm
7670 has a mean diameter of sqrt(69.5x61.5) = 65.38mm
rotational inertia = geometric constant depending on shape x m x R^2
m = another geometrical constant depending on shape x density x R^3
to sum up,
inertia = geometric constant depending on shape x density x R^5
in the real world, blade thickness does not go up directly with radius, and inertia is proportional to R^4.333 if the section is stiffness-limited, or R^4.666 if the section is strength-limited , which is probably the case here. Nevertheless, we will take the average of the two and use R^4.5 instead (which would work out in the 7670's favor)
density of inconel = 8.1
density of gamma-Ti = 4.0
assuming the geometric constants are the same,
I GT30 / I 7670 = (8.1 x 57.44^4.5)/(4.0 x 65.38^4.5)
I GT30 / I 7670 = 1.131
So a simplistic analysis shows that the GT30 turbine wheel has 13.1% more rotational inertia than the 7670, but this does not take into account the MUCH greater thickness of the 7670 blades, the superback section of the 7670 (which puts mass where it affects rotational inertia the most), and the longer/thicker nut section (which would have a minor effect on rotational inertia) The superback section ALONE has got to be worth more than the 13% difference between the two turbines, and we STILL haven't taken into account the thicker cross section of the gamma-Ti wheel!
The worst case scenario conclusion we can draw from the above is that the 7670 turbine wheel does NOT have a lower PMOI than the GT30, in fact its probably higher... The 7064 would have a significantly lower PMOI than the GT30 but then again it flows less given a similar housing... I hope I've made my point clearly
PS - I'm not passing judgement as to which of the above turbine wheels is "better", or more efficient, or faster spooling, just comparing their relative rotational inertias.
GT30 turbine has 60mm inducer and 55mm exducer
7670 turbine has 69.5mm inducer and 61.5mm exducer
both of them have 10-blades
GT30 has a mean diameter of sqrt(55x60) = 57.44mm
7670 has a mean diameter of sqrt(69.5x61.5) = 65.38mm
rotational inertia = geometric constant depending on shape x m x R^2
m = another geometrical constant depending on shape x density x R^3
to sum up,
inertia = geometric constant depending on shape x density x R^5
in the real world, blade thickness does not go up directly with radius, and inertia is proportional to R^4.333 if the section is stiffness-limited, or R^4.666 if the section is strength-limited , which is probably the case here. Nevertheless, we will take the average of the two and use R^4.5 instead (which would work out in the 7670's favor)
density of inconel = 8.1
density of gamma-Ti = 4.0
assuming the geometric constants are the same,
I GT30 / I 7670 = (8.1 x 57.44^4.5)/(4.0 x 65.38^4.5)
I GT30 / I 7670 = 1.131
So a simplistic analysis shows that the GT30 turbine wheel has 13.1% more rotational inertia than the 7670, but this does not take into account the MUCH greater thickness of the 7670 blades, the superback section of the 7670 (which puts mass where it affects rotational inertia the most), and the longer/thicker nut section (which would have a minor effect on rotational inertia) The superback section ALONE has got to be worth more than the 13% difference between the two turbines, and we STILL haven't taken into account the thicker cross section of the gamma-Ti wheel!
The worst case scenario conclusion we can draw from the above is that the 7670 turbine wheel does NOT have a lower PMOI than the GT30, in fact its probably higher... The 7064 would have a significantly lower PMOI than the GT30 but then again it flows less given a similar housing... I hope I've made my point clearly
PS - I'm not passing judgement as to which of the above turbine wheels is "better", or more efficient, or faster spooling, just comparing their relative rotational inertias.
Your post's content and perspective have always been interesting...I'm curious who you work for.