STOCK LOCATION TURBO SHOWDOWN!
Posted on: February 4, 2016
I will start with the background on what motivated us to do this test. We see a lot of different cars with a lot of different parts go toe to toe on our all-wheel-drive dyno dynamics dynamometer, and with no two cars being the same it can be hard to pinpoint just what turbo really throws down the best power.
A customer came to us with a very specific goal. He wanted us to figure out what turbo would make him at least 450whp and 450wtq. We decided to test out a few stock location turbos… Nine of them in total! The retail value of the tested turbos was a somewhat staggering 15,223 dollars!!!
HERE IS A LIST OF THE CONDITIONS THAT ALL TURBOS WERE TO BE TESTED UNDER:
- All had to be true bolt on stock location turbos, meaning 2.5″ inlet and ihi flange.
- All turbos were tested with a Turbosmart 45mm external wastegate containing a 14psi spring to ensure that internal gate inconsistencies could not affect the performance.
- Same car, same tank of E85, no changes to any other mechanical systems.
PARAMETERS:
- We allowed a 15-minute cool down before any final numbers were recorded, two runs back to back, highest run recorded.
- We monitored the Carbon Monoxide level in the room constantly to make sure exhaust gases were not building up to unacceptable levels in the dyno cell.
- All turbos were run at “pump gas” friendly 21psi, as well as 25psi high boost tune. We did our best to record all results within +/- .5psi.
- The Air fuel ratio was run at as close to 12:1 as we could manage on every recorded run.
- All runs are weather corrected since testing was done over multiple days.
THE CAR:
The car used for this test was a 2005 Legacy GT. This is a quick list of mods, if nothing is mentioned assume it is stock. All dyno pulls were made on a single tank of E85 confirmed at 82% ethanol.
ENGINE:
- CP 9.0:1 forged pistons
- Manley H-beam rods
- Manley 37mm intake valves
- Manley 33mm exhaust valves
- Manley springs and retainer kit
- GSC s1 cams
- Tomioka Racing Unequal Length Header
- ETS FMIC kit
- Tomioka Racing turbo inlet tube
- TGV deletes
- 700whp fuel system
- K&N 2.75” intake
- Cobb access port was used for tuning in speed density.
THE TEST:
I just want to clear up one thing before we get to the numbers. Some of the turbos tested only have results for 21 psi because this was the highest boost level we could achieve on these turbos. Wastegate duty cycles were at 95% on these turbos.
All of the gt28 based turbos, the Tomioka, and the Steam speed included really seemed to struggle with this problem. I would suggest not buying either of these if you plan on running any more than 21psi.
TOMIOKA GT28 – 21PSI-TAPERING 19PSI
- DYNO ROOM TEMP = 66 *
- HUMIDITY = 77%
- BARO = 30.0
- WEATER CORRECTION FACTOR = .975
- CO = LESS THAN 100PPM
- MAX POWER = 412WHP
- MAT TORQUE = 394WTQ
- RETAIL PRICE = $1695
REVIEW:
This one really fell short on our testing. It didn’t spool very well for a small framed turbo, with boost finally peaking all the way up around 4700rpm. Also, notice the strange shape of the boost curve.
This was a problem we noticed with both of the gt28 based turbos we tested. This turbo could not reach above 21psi either, it does however have a decent peak power output for such a low boost level.
Fitment is good, and the kit comes complete with everything needed for install.
- DYNO ROOM TEMP = 61 DEGREES
- HUMIDITY = 77%
- BARO = 30.05
- CO = LESS THAN 60PPM
- WEATHER CORRECTION FACTOR = .970
- MAX POWER = 426WHP
- MAX TORQUE = 400WTQ
- RETAIL PRICE = $1799
REVIEW:
All of the dominator turbos we tested performed well. This was the biggest we tested, and it was optioned with the 8cm housing. For its size, it spooled pretty well, and it made great power on both low and high boost. If you’re looking for maximum horsepower out of your 2.5 inlets, this is your best bet.
- DYNO ROOM TEMP = 64 DEGREES
- HUMIDITY = 75%
- BARO = 30.05
- CO = LESS THAN 60PPM
- WEATHER CORRECTION = .969
- MAX POWER = 463.5WHP
- MAX TORQUE = 455WTQ
- DYNO ROOM TEMP = 66 DEGREES
- HUMIDITY = 71%
- BARO = 30.05
- CO = LESS THAN 32PPM
- WEATHER CORRECTION = .976
- MAX POWER = 418.3WHP
- MAX TORQUE = 398WTQ
- RETAIL = $1699
REVIEW:
This is just a good turbo on all counts, spools well make great power and look the best out of all the others in its size. We tested this in both housing sizes, this 8cm version would be best suited to stock engines cars with a relatively low powerband.
- DYNO ROOM TEMP = 67 DEGREES
- HUMIDITY = 71%
- BARO = 30.00
- CO = LESS THAN 130PPM
- WEATHER CORRECTION = .970
- MAX POWER = 440.9WHP
- MAX TORQUE = 431WTQ
- DYNO ROOM TEMPERATURE = 62 DEGREES
- HUMIDITY = 87%
- BARO = 29.77
- CO = LESS THAN 80PPM
- WEATHER CORRECTION FACTOR = .985
- MAX POWER = 407WHP
- MAX TORQUE = 382WTQ
- RETAIL = $1599
REVIEW:
This is another one of the gt28 based ball-bearing turbos, and just like the Tomioka, it fell short of expectations. It could not reach a target boost higher than 21psi and made just slightly less power than the equivalent from them as well.
Another note on this, they ship the turbo with steel braided coolant lines with adapters to barb. The barbs are not the correct size for the stock Subaru 1/2 coolant hoses. So I had to do some adapting to make it work as intended. This makes for a very “unclean” installation.
- DYNO ROOM TEMP = 61 DEGREES
- HUMIDITY = 86%
- BARO = 30.05
- CO = LESS THAN 100PPM
- WEATHER CORRECTION FACTOR = .960
- MAX POWER = 430.9WHP
- MAX TORQUE = 405WTQ
- RETAIL = $1490
REVIEW:
We have used this turbo in the past on some customer cars, and it’s a solid all-around choice. It spools reasonably well for the power and makes good power on pump gas boost levels. The other nice thing about this kit is it includes a new top mount intercooler elbow, as well as a couple of different options for feed lines.
Also, notice that this turbo did not pick up much power at a higher boost. It’s just running out of its high-efficiency range up top to make the big numbers, but the torque did swell nicely on the spike.
- DYNO ROOM TEMP = 65 DEGREES
- HUMIDITY = 85%
- BARO = 30.00
- CO = LESS THAN 60PPM
- WEATHER CORRECTION FACTOR = .971
- MAX POWER = 428WHP
- MAX TORQUE = 405WTQ
- RETAIL = $1349
REVIEW:
This was actually one of the surprise turbos in the bunch that we tested. It spooled nearly identically to the Dominator 1.5XTR 8cm but did not produce the same power per pound of boost during that time. This turbo made strong numbers on both low and high boost and has one of the best price points of the bunch.
- DYNO ROOM TEMP = 65 DEGREES
- HUMIDITY = 85%
- BARO = 30.00
- CO = LESS THAN 60PPM
- WEATHER CORRECTION FACTOR = .971
- MAX POWER = 434.3WHP
- MAX TORQUE = 435WTQ
- DYNO ROOM TEMP = 67 DEGREES
- HUMIDITY = 82%
- BARO = 30.00
- CO = LESS THAN 100PPM
- WEATER CORRECTION FACTOR = .994
- MAX POWER = 428WHP
- MAX TORQUE = 418WTQ
- RETAIL = $1249
REVIEW:
This is the td05 exhaust housing version of the STX67. It could not produce above 21psi because of the reduced turbine size but It did however make identical power to the larger turbine version, and the spool difference is negligible.
I recommend spending the 100 bucks to go to the td06 version unless you’re running a 2.0l engine.
- DYNO ROOM TEMP = 67 DEGREES
- HUMIDITY = 86%
- BARO = 29.76
- CO = LESS THAN 100PPM
- WEATHER CORRECTION FACTOR = .995
- MAX POWER = 415WHP
- MAX TORQUE = 408WTQ
- RETAIL = $949
REVIEW:
The HTA71 has the smallest housing sizes of any of the turbos we tested. It spools reasonably well and makes pretty solid numbers at pump gas boost levels. We did pretty much max it out during our tests at 415whp.
That being said, it still has the best power per dollar ratio out of everything we tested. If you’re looking for around 400whp and on a budget then this thing can get it done.
- DYNO ROOM TEMP = 70 DEGREE
- BARO = 30.02
- HUMIDITY = 86%
- CO = LESS THAN 100PPM
- WEATHER CORRECTION FACTOR = .984
- MAX POWER = 432WHP
- MAX TORQUE = 445WTQ
- RETAIL = $1699
REVIEW:
This turbo was not originally part of our test lineup, but because of the power output of the 2.5XTR at high rpm, we were thinking this might deliver the best of both worlds for our customers. His power goals were 450wtq/450whp with the awesome spool.
Well, it was delivered. With the headwork this car has I believe that the 8cm housing is just a bit too small. Because of this, the 10cm version was able to spool just slightly faster, and absolutely kill it on the top end where the turbine housing was continuing to flow well.
Hands down this were the best turbo of the bunch, especially on our test car
- DYNO ROOM TEMP = 70 DEGREE
- BARO = 30.02
- HUMIDITY = 86%
- CO = LESS THAN 100PPM
- WEATHER CORRECTION FACTOR = .984
- MAX POWER = 472.8WHP
- MAX TORQUE = 472WTQ
CLOSING:
Overall there are a lot of solid performers in this group, and most are likely not to be disappointed with the majority of these choices. One thing I will say about these graphs is to pay close attention to the power output at the very beginning of the graph.
There is a big difference in the way these turbos drive around town. The gt28’s are just dogs anywhere out of boost, while the most responsive of these being the once again the Dominator 1.5XTR, especially the 8cm version.
Please keep in mind also that if you are looking for even more power, that the real restriction on these turbos was the 2.5” inlet diameter.
There are countless other options when you step up to the 3” inlet that will put down over 500whp. Hopefully, this will help some of you make a more educated decision when spending over $1000 bucks on your next power adder!!!
