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Garrett has now launched a new journal bearing challenge to the Borg Warner SX-E line-up
the two relevant GBC turbos are tagged GBC 35-700 which crosses towards the SX-E 7670 and the GBC 37-900 aimed at the SX-E 63.
here's an initial comparison
.................................................. .............GBC 35-700...........................................BW SX-E 63....................GBC 37-900................................SX-E 63
compressor area average sq inch area........5.57.................................. ........................5.52...................... ..........7.03.................................... ..7.06
compressor trim............................................58 .................................................. .........56..................................64... .......................................52
turbine area average sq inch area............5.13.............................. ............................5.64.................. ..............5.81................................ ......7.15.
max compressor efficiency..............................78%....... .................................................. .75%................................74%........... ........................76%
max compressor flow................................68 lbs minute............................................ ..64...................................87......... ...............................77
boost level at max flow.............................23.5................................................... ........35................................23.5.......................................32
max rotary est rwhp.....................................510...... .................................................. ...480.................................657........ ...............................577
retail price............................................. ......$1107....................................... ..................848............................. ..1289....................................1050
neither the GBC or SX-E are water cooled and both have up-engineered journal bearings w 360 thrust bearings. neither of these features pose a problem for the rotary.
just like the excellant SX-E line expanded our turbo options considering that they are priced less than half of the similar output $2300 EFR 8374, the GBC offers an attractive option to the G line. my G40-1150 retails for $3350.
during 2018 i spent a lot of time evaluating the budget priced SX-E 62. i compared both T4 hotsides and found really good power at 8800 (even) with the smaller (.91) hotside. my bet is the newer tech GBC line will raise the bar.
time and Tech marches on,
welcome Garrett to the party.
Last edited by Howard Coleman; 07-08-23 at 05:08 PM.
the max turbine flows are fairly limited on both though, it would be best to study and understand what their wankel engine output limits will be.
Because again, turbine A/R is only a relationship and there are two different size turbine wheels offered on the BW S300SX-E model; 76mm and 80mm. BW offers 0.91A/R for both, but where some people might not understand is that the peak flow limit on the 0.91 76mm turbine is lower than the 0.91 80mm turbine.
When comparing the same turbine design it’s easy to come to this understanding; all else being equal the larger wheel flows more than the smaller wheel. The other take-away in studying the chart above is that the smaller wheel with same A/R is equivalent to the larger turbine wheel with a smaller A/R wrt flow swallowing capacity.
The reason for this post is that I’m pretty sure you’re referring to the larger BW 80mm turbine in the S362SXE reference example. Things get trickier trying to compare different turbine wheel designs. Comparing wheel area ratios and such isn’t going to bring you to the correct understanding. Like A/R, it’s just a dimensional relationship. All it really provides is larger is more and smaller is less within the same design, without any meaningful reference for making a true comparison with other turbine designs.
So now making an actual comparison based on turbine housing mass flow swallowing capacity, the new Garrett G37 0.95 A/R turbine housing is only showing a max flow limit of 30 lbs/min @~2.4 P.R on the turbine map. Which just so happens to only be equivalent to the smaller BW S362SXE 76mm 0.91 A/R turbine. So if you were using the larger 80mm turbine, then it can never swallow the same exhaust flow energy that was being achieved on your example, especially at 8800 rpm.
Based on my own understanding of the BW exhaust flow phi map I’d approximate it to being equivalent to the BW 80mm turbine wheel with a 0.80 A/R turbine. Except they don’t offer an A/R housing that low. That’s the purpose and intent of the smaller 76mm turbine wheel they offer instead.
Regardless of the compressor flow capacity, I doubt a Garrett G37 0.95 A/R will see much more than lowish 500 whp on a 13B until such time they offer a larger A/R turbine housing. The emap will be getting pretty high otherwise. It could come down to various factors, but it’s not something you’d want to be beating hard on for an extended period.
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They may release other turbine housings in the future, but presently the 0.95 A/R T4 for the GBC35-700 and 0.95 A/R T4 for the GBC37-900 are the largest offered at the moment.
thought it was interesting that turbine flow actually decreases on the GBC35-700 past 2.25 P.R., most will just flatline
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the one thing I did overlook in the previous analysis is how early the turbine flow line is coming on. Potentially going to offer some spicy low-end response.
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02-24-23, 09:47 AM
