dsm-onster
DSM Wiseman
- 8,592
- 124
- Jul 11, 2004
-
Bloxom,
Virginia
As a farewell to my small 16g (sold it on ebay), here's a little bit of first hand experience had and study I've done with the turbo that may b beneficial. Some of you, of course, already know this. But, this is good info that I've noticed and think it should be brought up to those that don't know and are on the fence about which 16g turbo to buy.
I bought my small 16g instead of a big 16g for one VERY important reason. Vs. the big 16g, it is much more efficient and only flows about 2lb/min less. At 38lb/min flow at the edge of the map it has PLENTY of flow for a 350whp goal. The most common goal for a person buying a 16g.
The small big and evo3 16g have the same turbine wheel and turbine housing.
Small 16G:
1) Flows 38lb/min at 65% efficiency at 21psi (ambient pressure 14.67psi).
2) Smaller compressor wheel for faster spool speed
3) Over 70% efficiency up to 36lb/min and up to 25psi at that flow. Any lower boost at that flow or any less flow at higher boost is MORE efficient.
4) Higher efficiency islands. Less energy is wasted to heat instead of converted to boost. So it takes less exhaust energy to achieve a boost. Less exhaust energy means higher boost at lower rpms, or faster spool. The small 16g has a substancial 77% efficiency island
Big 16G:
1) Flows 572cfm at 60% efficiency at 25psi. 572cfm X .07 = 40lb/min.
2) Larger compressor wheel has more rotational inertial which slows spool.
3) Over 70% efficiency up to only 444cfm. 444cfm = 31lb/min. Anymore flow demand or any higher boost at that flow demand is under 70%.
4) There's no plus 71% efficiency island substancial enough in size to help reach boost with less back pressure than a small 16g. More back pressure at spool up and more lag equal LOTS less torque.
I've been around both turbos for years and the big 16g is always more laggy even after direct swaps and has always needed more timing tweeking during spool up, which I attribute to the less efficient compressor demanding more exhaust manifold pressure to get the job done. All for 2lb/min in peak flow??? My stock longblock except for fp2 cams with 3" exhaust and ebay fmic setup extracted 36lb/min from the small 16g, on a warm day at 22psi. If I want those extra 2lb/min, I'll get an evo3 16g and go for the extra 4lb/min it provides over the small 16g. In the meantime, the small 16g is FAR more efficient and spools noticably faster. Which is not a suprise since the small 16g was released after the big 16g was taken off of the evo cars. To me, the small 16g is MHI's revision of the big 16g.
The small 16g compressor map shows kg/sec for airflow. The big 16g map is unlabeled. But likely m^3/sec in airflow. Otherwise it would be in kg/se and not much better than the 14b compressor WRT flow.
Conversion factors:
(PR X 14.67psia) - 14.67psia = Boost
kg/sec X 60sec X 2.2046lb/kg = lb/min
m^3/sec X 60sec X 35.3ft^3/m^3 = CFM
CFM X .07 ≈ lb/min
I don't know about you, but the big 16g isn't worth it to me. Yet, for some reason they sell for the same price or more than the small 16g when new. The big 16g is older tech that produces marginally better results when pushed to the absolute limit and anywhere before that is inferior in almost every way.
The evo3 16g has the same size exducer as the big 16g and spools about the same because of it. It has a slightly larger inducer diameter and a smaller diameter hub, which increases flow. It also has thinner blades. Which I think makes up for the slightly larger inducer diameter to create the same spool speed of the big 16g. The evo3 16g also is still 70% efficienct up to about 38lb/min. Since it spools the same as the big 16g and flows 3lb/min more than the big 16g AND is still 70% efficient at up to 38lb/min, if you're willing to deal with slightly more lag than the small 16g to get more flow, then don't bother with the big 16g, IMHO. It only flows 2lb/min more thant he small 16g and the evo3 16g spools the same and is more efficienct.
Interestingly, the 151K rpm line is probably a safe maximum that MHI is showing for the sake of warrantee and oem applications, correct? Take a look at the 60% efficiency band on the small 16g compressor map. It is easy to extrapolate in your mind how the curve would look after 151K rpms. There's more flow there. You will have to push the turbo, but the bearing section is the same as the 14b bearing section, and the 14b has a 170K rpm line on the compressor map. I havn't calculated the tip speed of the small 16g at specific rpms, but it's clear that more flow is there. And as evidenced by many results with a clipped small 16g, the compressor can push more flow than 38lb/min.
I bought my small 16g instead of a big 16g for one VERY important reason. Vs. the big 16g, it is much more efficient and only flows about 2lb/min less. At 38lb/min flow at the edge of the map it has PLENTY of flow for a 350whp goal. The most common goal for a person buying a 16g.
The small big and evo3 16g have the same turbine wheel and turbine housing.
Small 16G:
1) Flows 38lb/min at 65% efficiency at 21psi (ambient pressure 14.67psi).
2) Smaller compressor wheel for faster spool speed
3) Over 70% efficiency up to 36lb/min and up to 25psi at that flow. Any lower boost at that flow or any less flow at higher boost is MORE efficient.
4) Higher efficiency islands. Less energy is wasted to heat instead of converted to boost. So it takes less exhaust energy to achieve a boost. Less exhaust energy means higher boost at lower rpms, or faster spool. The small 16g has a substancial 77% efficiency island
Big 16G:
1) Flows 572cfm at 60% efficiency at 25psi. 572cfm X .07 = 40lb/min.
2) Larger compressor wheel has more rotational inertial which slows spool.
3) Over 70% efficiency up to only 444cfm. 444cfm = 31lb/min. Anymore flow demand or any higher boost at that flow demand is under 70%.
4) There's no plus 71% efficiency island substancial enough in size to help reach boost with less back pressure than a small 16g. More back pressure at spool up and more lag equal LOTS less torque.
I've been around both turbos for years and the big 16g is always more laggy even after direct swaps and has always needed more timing tweeking during spool up, which I attribute to the less efficient compressor demanding more exhaust manifold pressure to get the job done. All for 2lb/min in peak flow??? My stock longblock except for fp2 cams with 3" exhaust and ebay fmic setup extracted 36lb/min from the small 16g, on a warm day at 22psi. If I want those extra 2lb/min, I'll get an evo3 16g and go for the extra 4lb/min it provides over the small 16g. In the meantime, the small 16g is FAR more efficient and spools noticably faster. Which is not a suprise since the small 16g was released after the big 16g was taken off of the evo cars. To me, the small 16g is MHI's revision of the big 16g.
The small 16g compressor map shows kg/sec for airflow. The big 16g map is unlabeled. But likely m^3/sec in airflow. Otherwise it would be in kg/se and not much better than the 14b compressor WRT flow.
Conversion factors:
(PR X 14.67psia) - 14.67psia = Boost
kg/sec X 60sec X 2.2046lb/kg = lb/min
m^3/sec X 60sec X 35.3ft^3/m^3 = CFM
CFM X .07 ≈ lb/min
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I don't know about you, but the big 16g isn't worth it to me. Yet, for some reason they sell for the same price or more than the small 16g when new. The big 16g is older tech that produces marginally better results when pushed to the absolute limit and anywhere before that is inferior in almost every way.
The evo3 16g has the same size exducer as the big 16g and spools about the same because of it. It has a slightly larger inducer diameter and a smaller diameter hub, which increases flow. It also has thinner blades. Which I think makes up for the slightly larger inducer diameter to create the same spool speed of the big 16g. The evo3 16g also is still 70% efficienct up to about 38lb/min. Since it spools the same as the big 16g and flows 3lb/min more than the big 16g AND is still 70% efficient at up to 38lb/min, if you're willing to deal with slightly more lag than the small 16g to get more flow, then don't bother with the big 16g, IMHO. It only flows 2lb/min more thant he small 16g and the evo3 16g spools the same and is more efficienct.
Interestingly, the 151K rpm line is probably a safe maximum that MHI is showing for the sake of warrantee and oem applications, correct? Take a look at the 60% efficiency band on the small 16g compressor map. It is easy to extrapolate in your mind how the curve would look after 151K rpms. There's more flow there. You will have to push the turbo, but the bearing section is the same as the 14b bearing section, and the 14b has a 170K rpm line on the compressor map. I havn't calculated the tip speed of the small 16g at specific rpms, but it's clear that more flow is there. And as evidenced by many results with a clipped small 16g, the compressor can push more flow than 38lb/min.
I have a small 16g on my laser and love it
