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I'll take an 18k any day of the week. My stock block Evo X on E54 makes 100 more wtq than this turbo at 4k rpm. This turbo is pretty laggy for how small it is...
200- ft-lb at sub 3kRPM will NOT feel laggy at all, and torque that low represents a very good daily driver. It does look like it was tuned to limit torque, but the OP would have to confirm that. I think the graph looks good. Would I chose an 18k over this? Absolutely - Not enough data on things like long term durability and track abuse. This is why I asked him to post back at 10kmi intervals. But when someone does post data on something new/unknown, I think the common thing is for the Evo community to jump on their backs for not sticking with what everyone else has done. You gotta at least give'em credit for posting the graph and reporting results.
200- ft-lb at sub 3kRPM will NOT feel laggy at all, and torque that low represents a very good daily driver. It does look like it was tuned to limit torque, but the OP would have to confirm that. I think the graph looks good. Would I chose an 18k over this? Absolutely - Not enough data on things like long term durability and track abuse. This is why I asked him to post back at 10kmi intervals. But when someone does post data on something new/unknown, I think the common thing is for the Evo community to jump on their backs for not sticking with what everyone else has done. You gotta at least give'em credit for posting the graph and reporting results.
I credit the OP for buying, having it tuned, and posting the results. I think we can all appreciate the guinea pig so to speak as it helps the rest of the community. Hindsight 20/20, the results for a turbo that size are not that great in terms of spool and torque. The HP # looks to be where it should but why does the torque curve look like a 6266?! That’s my main concern. Sure it’ll be safe on the stock rods, but it won’t give you the push you back in your seat feel. Like I said compared to my 18k, which has a similar hp curve, the 18k makes 100 more wtq at 4K rpm.
Hi I'm Sam from SteamSpeed. I am happy to answer any questions you guys might have.
We've been manufacturing Subaru turbos for several years now. The STX 71 one of our most popular turbos for the STI with good reason, it can generally make over 400-450 whp on pump gas with the 59.5 lbs/min comp wheel (maps here). This turbo uses essentially the same CHRA. Obviously with a higher measured flow rate, and similar efficiencies, this turbo should make a little more power than an 18k while being about as responsive. Our initial testing indicates that this is the case.
For the STI/WRX, the historical repair rate is well below 5% on this model, which means the CHRA is super reliable. We'll see how it does in EvoX housings, and we know Evo guys like to hit higher boost targets, which does increase the shaft speed. Obviously we'll have to have had sold and have a lot of these out there for Evos to have statistically meaningful data for your cars, but the STI data is a good indicator that it should be fine.
I have some initial tuning data as well from EnglishRacing I can post up. Aaron was able to get a some more out of it, but the car in test had an restrictive O2 housing with well known boost creep issues that was causing us difficulties in testing. We did a teardown and inspection, and will be sending it back to English for more testing.
As for the turbine housing, we manufacture it with high nickel content D3 alloy in Taiwan. We didn't "invent" it, but it is a well vetted housing design at this point.
Anyway, let me know what else you' d like to know about this turbo.
Here was the initial data we got back from English Racing. It had some creep, so we owe Aaron a ported housing for them to use for more testing. That particular car had an O2 housing that was well known for causing boost creep. As you can see from the original poster who had an external dump O2 housing, he didn't have any creep issues.
Here is the data from their dyno using pump gas:
Dyno result from English Racing
Aaron said it did about 475 whp on pump gas.
Here are the plots from the data logs of that car from before (stock turbo) and after with the STX 71.
As you can see, you gain +100 whp, and give up close to nothing. And as the OP stated, it feels the same as stock down low in terms of responsiveness.
