Ryan Milliken, an invaluable contributer to Diesel Tech Magazine, took a few turbos for a test drive. Here is his findings.
While spending some time at ATS I managed to get some hands on time with the Aurora 5500, a Borg Warner based charger which has come A LONG ways from its roots. This charger was closest in spec to the GTX4202R/1.01AR that I showed up with so we thought it would be fun to compare them back to back and try a few things a long the way... so we did!
Specs on the A5500 as tested: 76mm inducer compressor in 7 blade cast and billet and 6 blade billet, 86mm inducer turbine wheel, 1.0AR turbine housing. Oil cooled/lubricated, journal bearing. Brand new, hand delivered from the turbo shop to the dyno.
Specs on the GTX4202R as tested: 76mm inducer compressor in 11 blade billet, 82mm inducer turbine, 1.01AR turbine housing. Oil lubricated ball bearing, water cooled. Brand new cartridge (compressor/cartridge/turbine) installed for the test and other than old compressor and turbine housings, we're in perfect shape.
What is the difference between an A5500 and an S400? Nearly everything. At first, externally they appear to be the same thing, until you spot the two bolt flanges that hold the compressor cover to the housing instead of the v-band clamp you're used to seeing. Internally, the biggest difference is the shaft size/mass, with the Aurora series being much lighter and smaller than the S400, this directly results in the awesome spooling characteristics this charger has versus comparatively sized turbochargers (including my GTX42!). One could say this smaller shaft would make the charger susceptible to failure, however I have an amazing ability to destroy anything I touch with ease and after a few dozen 7/800hp pulls on the dyno, 3 different compressor wheels, and a few highway pulls, the A5500 was still in perfect shape.
First impressions on the A5500 versus the GTX that I've been using for a few months was that I could spool the thing with ease, even at 5300', it came alive quicker on the dyno and out in the parking lot I could easily brake stall the truck up to 30psi in just a few seconds with NO SMOKE. Also, the six blade compressor wheel (the only one I street tested) has an awesome tone to it that's very noticeable, even over the exhaust. Where the GTX has a bit of turbine whine but the 11 blade compressor is very quiet. On the street I couldn't tell a difference between the two, end result was the same, rolling burnouts, whether in 2wd or 4wd, factory take-off 265 E-rated tires and nearly frozen Denver black top was insane.
On the dyno (mustang), the quick spooling of the A5500 became apparent as it came alive 100-200rpm earlier than the GTX42 resulting in a bigger torque number than the GTX42, but the power coming on harder and earlier came at the expense of giving up some on the big end. Literally, a 15lb torque gain for a 15hp loss. I can't even give an answer as to which one makes more power because they're tied, with their differences being able to be sorted out by moving your shift strategy 150rpm up or down the power curve.
With the GTX4202R selling for $3029 and the CAST WHEEL Aurora 5500 selling for $2279 (prices on 6 blade billet up ASAP), based off of the testing I've done, I'd call the A5500 a far better bang for the buck for those of you looking for a single charger in the 800hp range without sacrificing street manners!
Aurora 5500 806hp/1531
GTX4202R 821/1516
Wondering what the "w/air filter" blue line is about? Yeah, me too. That's a 5" ID AFE Dry Filter, one of the standard grey ones we all use with our 2nd gen kits. This run was done immediately prior to the 821/1516 run, the only change was removing the filter. I'll be trying out a few different filter setup's before race season but ultimately I'm shopping for an additional headlight housing to take a hole saw to and run filter-less for race season, keeping a filter for the street.
Check with Hardway Performance owner Ryan Milliken for more great information and products at the Hardway Performance website.
http://hardwayperformance.com/.