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Old 01-02-2016, 01:36 PM   #476
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Quote:
Originally Posted by Nick411 View Post
Again, maybe his driving style on those shorter/tighter tracks is better suited to the smaller housing. Making the smaller housing faster. Is he changing his tune between the housings? If not than his tune is only optimized for one of the housings, making the other housing wrong for his setup. You can't just swap housings and go.

I've never said the largest housing is the best, out cars don't flow enough exhaust gas nor rev high enough to need the flow ability of something as large as a 1.06 unless it's a 1000whp drag car running 50+ psi. You generally want to match the housing so you make peak hp at redline while maintaining the widest torque curve possible.

My ej207 with a 5 speed compared to a ej257B with a 6 speed was a bit of a stretch. It was an extreme to get across my point of more power down low doesn't mean faster. Lets make it a pro tuned "stage 2" ej255 in an 09 WRX (265 version). Power band ends at ~6000rpm like the STI, slightly less peak power than the STI but similar curves, and the same ratios from the 5 speed (as close to equal as I can get from personal experience but with different power band locations). Even though it makes 50wtq more than I do, I pull on it because my power band is just as wide but torque and hp curves are about 1200rpm higher in rpm, which allows me to start the pull in a lower gear (3rd instead of 4th), which more than makes up for the difference in torque at the motor. Since we have the same ratios, we shift at relatively the same time (I shift slightly faster as I'm accelerating through the gears faster because I'm in a shorter ratio), but I'm always in a lower gear meaning I'm always accelerating at a faster rate at a given speed. Again, an example of more power down low doesn't mean faster. In this case it actually means it's slower because that low end power is sacrificing top end to the point where they have to be in a taller gear.

I'm not saying peak hp is what makes the car fast, it's where it makes it's peak hp and how long it can hold a flat torque curve. The longer you can increase, or at least hold your acceleration Gs, the faster you'll be. More peak hp/tq but in a narrower power band won't do that, I agree, unless it makes significantly more power resulting in a larger area under the curve. If both housings give you the exact same numbers/curves/power bands/etc., the housing that puts it's power band higher in the rpm rage will allow the driver to be in a lower gear at a given speed.

The main reason people think a smaller housing is faster, or it actually does end up being faster is not everyone understands that you can't drive a 0.82 like a 0.63 and not expect to be slower, or they do but they still drive the 0.82 like a 0.63, and/or don't know how to drive the 0.82 properly and blame it on the housing. The larger housing has to be driven accordingly for it to be faster. I.e. staying in the power band of that housing by staying a gear lower than you would with the smaller housing, slipping the clutch to keep the rpms up, brake boosting in the corner, etc.

The more torque you have at your axles, and the longer you have it, the faster you'll be. Sometimes it's a smaller housing, but most of the time it will be one of the larger housings. The only time you should go with a smaller housing is if you spend a measurable amount of time below the power band of the larger housing and you don't have the option of being in a lower gear.

Not to mention more power down low is harder on parts....
Some good points there, makes more sense with more detail. He has 2 different tunes for the 2 different housings. Yeah i meant back to back weekends, not on the same day, but still with no other changes.

I agree to some extent that you have to drive a larger housing car differently, but if you come out of a corner at a speed just too high for 2nd gear, the 0.63 will accelerate faster out of the corner in 3rd gear than the 0.82.

Power is a function of torque and rpm. So yes you are correct in saying that the higher the torque is in the rev range the more power the engine will make and the faster the car will be (assuming you can keep it in its torque window).

Only real way is to test back to back in exactly the same conditions which is very tricky.

To be honest it sounds like either housing will be a tonne of fun, but for everyone reading this have a good think about which housing would suit your use of the car the best.
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Old 01-02-2016, 03:12 PM   #477
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I agree with nick411 for 98% of his posts here. I think the bigger housings are usually underutilized in the subi community. They can benefit you in that you will have less backpressure up top and have a higher air density which makes your intercooler have less work to do and help with running cooler all around.
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Old 01-04-2016, 12:54 AM   #478
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Originally Posted by Nick411 View Post
The 0.63 would only be faster in lower RPMs as it will spool faster, but if you drive accordingly and stay above the RPM that the turbo hit's full boost at the benefits of the smaller housing begin to be outweighed by it's drawbacks in the higher RPM range. The 0.82 will allow you to stay in gear longer as it holds power further into the RPM range, this will make you faster than a 0.63 if you never dip below the RPM the turbo makes full boost at, i.e. when you drive a 0.82 like a 0.82 and not a 0.63. This also allows you to be in a lower gear for a given speed meaning you will have more axle torque and accelerate harder when you get on the throttle.

...
... The only time a smaller housing would be beneficial is in auto-x where you are constantly below the RPM where the turbo would make full boost on a larger housing and you don't really have a choice to shift down as you're in 2nd most of the time already. Other than that the larger housing will be better as it will be faster and it's easier on the bearings and internals as it's not making torque as low as the smaller housing.
Technically the car that gets its torque first will be fastest as catching up and then passing requires quite a bit more power. Trying to compare two "identical" cars except for turbine housings isn't the right way to look at it.
Technically again, in autoX ("depending on the setup") a smaller turbine/larger housing is probably better because it poses less restriction to the motor and allows for better off-boost power/response. In a large turbine/small housing scenario the engine is relying on boost pressure to produce power/response, so while on a dyno might look "better" because its 4th gear spool is at a lower rpm... in the real world it gets its power slower with regards to time.

Quote:
Originally Posted by ShinjiML View Post
The transient response of the turbo is still there despite a bigger housing, as that's determined by the compressor side. So, as long as the car is driven within its efficiency range, it will still feel responsive.

For mountain runs, I like the power delivery of the bigger housing as I roll onto the throttle halfway around a corner through corner exit. It feels smooth and easy to control and as I come up to the next corner in a straight section, I can hold the same gear to a higher RPM because the power doesn't drop off, which means there's less need to shift between corners. Then, depending on the speed of that next corner, I may be able to hold the same gear again through the corner and still stay in the meat of the powerband because of how high I can stay in the powerband upon corner entry.

Then there's the option of doing 1/4 mile runs, where the top end will shine as well.

All of that said, of course either of the .63 or .82 housing setup will be much faster than a stock turbo. A lot of people love violent spool and punchy low end torque. I agree, it's fun and makes the car feel fast, but I feel that the .82 AR is the more balanced of the two. For me, the bigger housing offers more power in the range that I use, so why not?
This... your driving experience is an accurate representation of the ability to push more torque at higher rpm if the smaller turbine housing isn't allowing safe power production.

Quote:
Originally Posted by Harey View Post
Nick411, no way in hell power is dropping off in 2nd gear with a 0.63.

A local guy here with a quick track car and a GT30 actually changes between 0.63 and 0.82 housings depending on the track. Tighter, lower speed track he is much faster with the 0.63 but the more wider higher speed track he is faster with the 0.82. Even the tighter, lower speed track would still not get below 60mph.
If he has to change housings and picks up that much speed then his whole setup is compromised to begin with. If he needs a .63 housing on a gt3076r then the turbo is just too big to begin with, so it isn't a matter of the smaller housing outperforming the large one, it is a function of a bad setup for that track and trying to make the most out of it. The easiest solution would be to run it to 7800-8000rpm to make the most out of that turbo (and run the .82 or 1.06)


Quote:
Originally Posted by KillerBMotorsport View Post
^ A rough generalization, but a GTX3067 flows similar to a GTX3071, which flows similar to a GT3076
On a Subaru the gtx3067r will not perform similarly to the gtx3071r or the gt3076r as they will both be around 500whp capable where the gtx3067r will be done in the 450whp range.

Quote:
Originally Posted by Nick411 View Post
Harey, do you know if his driving style changes between the housings? If he's not than he's driving the larger housing like it's the smaller housing, which is wrong. I too have a local time attack guy that used to run a gtx3076 with a large housing, and on the smallest and tightest local tracks he kept the large housing, and he won those rounds and went on to win the championship in his class, super street awd. He then went to a gt35 (don't know which, probably the gtx3576), with a large housing, and set the record for his class at every track. The fastest awd car at the smallest local tracks is running a gt35 with a large housing, which goes against everything you're saying. He drives it accordingly for the large housing, i.e. not flooring it out of a corer below 4000rpm and expecting something to happen.

I have a bone stock v7 ej207 with no more than a short ram intake and a catless turbo back exhaust making 300whp/245wtq...... I make my power up high, and rev higher than they do so I start in a lower gear. Yes I make less power at the motor, but from the start to the end I make the same or more at my wheels because I'm always in a lower gear than they are.


The guy (blurred) here that has posted his "spoolinator-ish" type setup that's running a gtx2867 is running a 0.86 housing (the largest available for that turbo) and hits peak torque by ~3200rpm and holds that torque to 6200, only drops 20wtq from 6200 to 7000, and makes peak hp at 7000 (redline). Your "the 3071 and below seem to be suited to the 0.63" statement is proven wrong by his setup, unless you're solely referring to gt30s. In which case I still disagree.
The gtx3076 and gtx3576 are the same turbo from a compressor standpoint, the 35r is the bigger turbine so it is laggier for the same power, there is no reason to switch from a gtx3076 to gtx3576... although if you did, you should be going from a 1.06 on the gtx3076 to an .82 on the gtx3576.

Your car reference and driving experience is a good example of why rpm is king. Low end power is useless if you can't keep it up.

Don't forget my car is still low power and would probably be similar to a gtx3067 on a .63, but I would still be more responsive on the road because I wouldn't be relying on making boost to get me going. That response is what you felt, and a gtx3067r making the same power would be a more typical hit throttle/take a moment/boost type of elastic band feeling.

a gtx3071 should never be running the .63 on a Subaru as it would be the turbo of choice in the 450-500whp range and you wouldn't be able to make that on the small turbine housing without forcing a lot of torque down low as you would be rpm limited (and run into the usual Subaru business of needing a block built to withstand a nuclear event)

Quote:
Originally Posted by Harey View Post
I think you are getting a bit off track here, you are bringing in lots of different factors standard turbos, 6 speed vs 5 speed, the competition in the class, different engine ej207 (which I also have).

The car we are talking about has a 7000rpm rev limit.

If the largest housing is always the best why not run the 1.06? If peak hp at redline is the only concern why not always run the biggest turbo possible?

Its the area under the curve that makes a car fast, not the peak hp.
Keeping the 7000rpm redline with a gt3076r is not the best way, he should be cammed and revving to 7800-8000rpm to have a wider powerband (keep torque in check at around 320-340wtq and hold it to 7500rpm+).

If not, then he should be getting a smaller turbo because it is not matched correctly to his needs.

As for area under the curve (kind of an old wives tale made up by muslce car owners and track racers with low hp...) Only if that power is manageable... so in reality the car with more peak hp is usually the car with power at higher rpm, or a higher redline/shorter gears and usually ends up being faster.


Quote:
Originally Posted by Nick411 View Post

I've never said the largest housing is the best, out cars don't flow enough exhaust gas nor rev high enough to need the flow ability of something as large as a 1.06 unless it's a 1000whp drag car running 50+ psi. You generally want to match the housing so you make peak hp at redline while maintaining the widest torque curve possible.
Sure they do, but it depends on the turbo. The gtx3076r loves the 1.06 when you are running properly in the 550+whp range and revving around 8k rpm (or running in the 500+whp range on pump gas). The larger turbine on the gtx3576r can use the .82 to make the same power/rpm range.
The 35r will still be laggier and should only be used on the gtx3582 instead when pushed higher into the 650whp range.
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Old 01-04-2016, 08:52 AM   #479
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Dont agree at all with "no point in switching from a GTX3076 to a GTX3576". From a lot of results on here it seems the GTX3076 is not a great choice on the ej25. Better to go smaller ie GTX3067 or 3071 or step up to a GTX3576.

KillerB works closely with Garrett and were advised the GTX3067 and the GTX3576 are their recommended choices for the ej25. Quite a few VERY impressive GTX3576 setups getting around.

Area under the curve is an old wives tale?? LOL cbf replying to it all
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Old 01-04-2016, 10:12 AM   #480
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On a Subaru the gtx3067r will not perform similarly to the gtx3071r or the gt3076r as they will both be around 500whp capable where the gtx3067r will be done in the 450whp range.
When you're pushing the limits of the turbo on E85, there are other choices that may be better. On pump, they most certainly will be VERY SIMILAR power wise, but spool very differently... unless you have plots that show otherwise?

I don't completely agree with your philosophy on turbine size and A/R, and there are many threads and tests already on the subject.

These are not apples to apples because they SAVCS and DAVCS as the spool-up characteristics show, but that's not worth all the 300-400 RPM difference shown. Besides that, both 2.5, stock valves/cams, etc...

GTX3067...




GTX3071...


Last edited by KillerBMotorsport; 01-04-2016 at 10:56 AM.
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Old 01-04-2016, 10:28 AM   #481
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Originally Posted by KillerBMotorsport View Post
When you're pushing the limits of the turbo on E85, there are other choices that may be better. On pump, they most certainly will be VERY SIMILAR power wise, but spool very differently... unless you have plots that show otherwise?

I don't completely agree with your philosophy on turbine size and A/R, and there are many threads and tests already on the subject.

These are not apples to apples because they SAVCS and DAVCS as the spool-up characteristics show, but that's not worth all the 300-400 RPM difference shown. Besides that, both 2.5, stock valves/cams, etc...

GTX3067...




GTX3071...

Corrected a typo for you
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Old 01-04-2016, 10:30 AM   #482
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Ok, well that makes very little sense to me. Your graphs show the GTX3071 has a better top end then the GTX3076. So are there more differences in these two examples? Or is that a .63 on the GTX3076?

Edit: Of that makes sense on the top end if ShinjiML is correct
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Old 01-04-2016, 10:59 AM   #483
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Originally Posted by ShinjiML View Post
Corrected a typo for you
Thanks!

Quote:
Originally Posted by Scuby04STi View Post
Ok, well that makes very little sense to me. Your graphs show the GTX3071 has a better top end then the GTX3076. So are there more differences in these two examples? Or is that a .63 on the GTX3076?

Edit: Of that makes sense on the top end if ShinjiML is correct
Yep, pre-coffee typo
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Old 01-05-2016, 08:33 PM   #484
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Originally Posted by Harey View Post
Dont agree at all with "no point in switching from a GTX3076 to a GTX3576". From a lot of results on here it seems the GTX3076 is not a great choice on the ej25. Better to go smaller ie GTX3067 or 3071 or step up to a GTX3576.

KillerB works closely with Garrett and were advised the GTX3067 and the GTX3576 are their recommended choices for the ej25. Quite a few VERY impressive GTX3576 setups getting around.

Area under the curve is an old wives tale?? LOL cbf replying to it all
It is a side-grade, not up-grade. Same compressor, same power production potential, so unless you are switching from a pump gas/race gas setup to an e85 and increasing exhaust volume to that extent but staying at the same power level there would be no reason to change (or maybe you have a very restrictive exhaust setup). Both turbos make the same power (same compressor...) The only difference would be slower spool on the road with the gt35 turbine (although the extra exhaust energy of e85 can negate most of that)
Garrett's recommended choices aren't always the best. Similar to matchbot but tested against known setups it can sometimes choose turbos 2 families away from what is actually used. So they can give reasonable generic choices but sometimes you can open their eyes when you choose something that they don't suggest and take it further than they thought (tuning and setup has a huge relationship when treating the turbo as part of a package and not as a bolt on tool)

What I mean with my "area" comment is that it is taking one tiny little piece of the puzzle and forgets everything else, like traction and gearing, power curve... its just one piece of the puzzle. So yes a higher average power engine is the more powerful lump, but put it in a car against one that makes its power in a more narrow widow but uses it more efficiently and everything changes.


Quote:
Originally Posted by KillerBMotorsport View Post
When you're pushing the limits of the turbo on E85, there are other choices that may be better. On pump, they most certainly will be VERY SIMILAR power wise, but spool very differently... unless you have plots that show otherwise?

I don't completely agree with your philosophy on turbine size and A/R, and there are many threads and tests already on the subject.

These are not apples to apples because they SAVCS and DAVCS as the spool-up characteristics show, but that's not worth all the 300-400 RPM difference shown. Besides that, both 2.5, stock valves/cams, etc...

GTX3067...




GTX3071...


What boost on the gtx3067?

I'm not sure what the comparison is between those to be honest, as you have a gtx3067r which is almost maxed out near the choke line and a gtx3071r that is still in the highest efficiency, centre of the compressor map and isn't being pushed... so the 3071 could easily take more boost and make quite a bit more power whereas the 3067 is pretty much done.
It would be nice to see both of those pushed all the way, have you? The davcs doesn't just help spool but also should also be able to hold power a few hundred rpm further to the right as well, is that on the 3071 car?

I'm not looking at spool because you cant see time on a dyno graph and time to torque is all that matters, not the rpm is comes at. Chasing spool on a dyno is a funny science, because in some cases I have seen a car that spools "later" on a dyno can hit boost and get its power sooner in the real world. Its also very important how that spool happens and how power is delivered, and typically choking down a big turbine to force it to spool can look "better" on a dyno sheet, and you can load that sucker up to produce good looking graphs, but if you were to drive it back to back against a smaller turbine (same compressor) with a larger housing you have a much better drive and allow the car to come up to power better and in most cases quicker.


btw, I'm not commenting on anything e85, it doesn't exist here, so just pump or race gas (or mix)
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Old 01-05-2016, 10:34 PM   #485
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It is a side-grade, not up-grade. Same compressor, same power production potential, so unless you are switching from a pump gas/race gas setup to an e85 and increasing exhaust volume to that extent but staying at the same power level there would be no reason to change (or maybe you have a very restrictive exhaust setup). Both turbos make the same power (same compressor...) The only difference would be slower spool on the road with the gt35 turbine (although the extra exhaust energy of e85 can negate most of that)

What boost on the gtx3067?

I'm not sure what the comparison is between those to be honest, as you have a gtx3067r which is almost maxed out near the choke line and a gtx3071r that is still in the highest efficiency, centre of the compressor map and isn't being pushed... so the 3071 could easily take more boost and make quite a bit more power whereas the 3067 is pretty much done.
It would be nice to see both of those pushed all the way, have you? The davcs doesn't just help spool but also should also be able to hold power a few hundred rpm further to the right as well, is that on the 3071 car?


btw, I'm not commenting on anything e85, it doesn't exist here, so just pump or race gas (or mix)
The GTX3576R spools up nearly identically to the GTX3076R even though the turbine flows significantly more. Why? Because the 3576 has a better blade speed ratio resulting in better turbine efficiency. Due to the better turbine efficiency, less pressure ratio is required to get the same turbine power. So, the 3576 spools virtually identically to the 3076 but allows the engine to make more power due to reduced back pressure from the larger turbine wheel. GTX3076 is generally a 550whp turbo (across many different engines) whereas the 3576 is 600whp.

A bit on blade speed ratio:
http://www.motoiq.com/MagazineArticl...p-Details.aspx

As for the GTX3067 vs GTX3071 plots, they are both at the same boost limit of pump gas. And on the 2.5L, that operating condition is well within the limits of the 3067 compressor map. Of course, you switch to race gas or E85 where you can run higher boost than pump gas, then the 3071 will make more power.
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Old 01-06-2016, 09:10 AM   #486
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Originally Posted by blurred View Post
Same compressor, same power production potential,

Both turbos make the same power (same compressor...) The only difference would be slower spool on the road with the gt35 turbine (although the extra exhaust energy of e85 can negate most of that)
You're not taking into consideration the turbine side and its effects on turbocharger performance for either the 30R or 35R, and the effects of backpressure.

GTX3067 and GTX30-anything else, do not share the same compressor wheel and have different aero characteristics as well. They are not the same.

Quote:
Originally Posted by blurred View Post
Garrett's recommended choices aren't always the best. So they can give reasonable generic choices but sometimes you can open their eyes when you choose something that they don't suggest and take it further than they thought (tuning and setup has a huge relationship when treating the turbo as part of a package and not as a bolt on tool)
We've been super fortunate to have some really great relationships in this industry, including engineering sources at Garrett. Honestly, every recommendation we've tested has been spot on and/or exceeded our expectations. Turbo selection tools are generic and do not take into consideration the engine design, intake and exhaust efficiencies, etc... The bits we recommend are based of engineering feedback and actual testing ON Subaru engines.

Quote:
Originally Posted by blurred View Post
What boost on the gtx3067?
22psi on the GTX3067

24psi on the GTX3071 (built engine)

Here is a boost plot (only) from the GTX3067 setup, 22psi...



Here is the GTX3071 with boost plot added...



Quote:
Originally Posted by blurred View Post
I'm not sure what the comparison is between those to be honest, as you have a gtx3067r which is almost maxed out near the choke line and a gtx3071r that is still in the highest efficiency, centre of the compressor map and isn't being pushed... so the 3071 could easily take more boost and make quite a bit more power whereas the 3067 is pretty much done.
It would be nice to see both of those pushed all the way, have you? The davcs doesn't just help spool but also should also be able to hold power a few hundred rpm further to the right as well, is that on the 3071 car?
You don't just crank the boost up on these cars, that's a recipe for disaster. More than anything these engines respond best to the improvements in flow brought on by a larger turbo. Case in point the HUGE power increase we saw going from the factory VF turbocharger to the GTX3067... at the same boost levels. Again, pump fuel.

Going to race fuel or E85, the capabilities of the turbochargers and the aggressiveness of the tune (boost, timing, etc...) can be pushed significantly. It's not something you want to do on pump fuel.

Quote:
Originally Posted by blurred View Post
Its also very important how that spool happens and how power is delivered, and typically choking down a big turbine to force it to spool can look "better" on a dyno sheet, and you can load that sucker up to produce good looking graphs, but if you were to drive it back to back against a smaller turbine (same compressor) with a larger housing you have a much better drive and allow the car to come up to power better and in most cases quicker.
All of our cars are tuned conservatively. We don't push for numbers, brake boost, or do anything to glorify the output. The keys are handed to the tuner and he tunes it just like any other, for reliability, longevity, and power. Pushing 'numbers' might sell parts initially, but we'd much rather have customer satisfied with the products they buy from us vs disappointed with the results. 'Numbers' we post will almost always be conservative.

If you're going to continue posting your thoughts on turbo setups and suggestions, you should follow up with real word data (plots, logs or whatever) showing as much. It would be much more valuable and relatable to the discussion.
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Old 03-17-2016, 12:00 AM   #487
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psst.. Chris I know Pete gave you a call about a quote... I'll probably not be ready by WBM this year... but this year the car will be up.
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Old 03-17-2016, 12:09 AM   #488
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Chris, have you guys had a chance to test the spoolinator with the 3576 setup?
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Old 03-18-2016, 02:52 PM   #489
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Chris, have you guys had a chance to test the spoolinator with the 3576 setup?
I know that was next on the list.

That is the setup I'm going with, or likely won't be ready till fall.
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Old 03-18-2016, 03:01 PM   #490
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Quote:
Originally Posted by CTSparky View Post
I know that was next on the list.

That is the setup I'm going with, or likely won't be ready till fall.
I almost don't want to see the results because I'm worried it'll be too good and I'll have to fight the urge to upgrade
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Old 03-19-2016, 10:25 AM   #491
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Quote:
Originally Posted by ShinjiML View Post
I almost don't want to see the results because I'm worried it'll be too good and I'll have to fight the urge to upgrade
Well I don't have a closed deck so it won't too high.
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Old 03-21-2016, 09:05 AM   #492
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psst.. Chris I know Pete gave you a call about a quote... I'll probably not be ready by WBM this year... but this year the car will be up.
We may have. I see very few orders/quotes myself unless it's something unique or new.

Quote:
Originally Posted by ShinjiML View Post
Chris, have you guys had a chance to test the spoolinator with the 3576 setup?
No Engine assembly is soon.

Quote:
Originally Posted by ShinjiML View Post
I almost don't want to see the results because I'm worried it'll be too good and I'll have to fight the urge to upgrade
I feel your pain on this one.
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Old 04-06-2016, 02:24 AM   #493
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Looking forward to that 3576 test... I've got a GT3076 and I just got my motor built to rev to 8500, anticipating a larger turbo next.

I'm a little mystified by the GTX3076 / GTX3576 choice. I wish there was good apples-to-apples comparison data out there, rather than just varying theories of how they should compare... the theories all sound plausible, too.
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Old 04-06-2016, 05:31 AM   #494
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There is apples to apples testing on the gtx3076 vs 3576.
Just get the 3576, its a fun turbo and spools fast. I have it with a .82 tial hot side
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Old 04-06-2016, 04:37 PM   #495
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Quote:
Originally Posted by Joshwrx04 View Post
There is apples to apples testing on the gtx3076 vs 3576.
Just get the 3576, its a fun turbo and spools fast. I have it with a .82 tial hot side
That is what I don't understand, I hear a lot about "just get the 3576 but the only back to back test on the same car I have seen was from Jeff Perrin and if I recall correctly he basically said get the 3076 or the 3582 that the 3076 and 3576 made nearly the same #'s just with the 3576 spooling a few 100rpm later. All the other cars I have seen changes more than just a turbo. But clearly I have not seen everything so if you have a link to other back to back tests I would love to check them out.

I have a GTX3076 .82 hotside on my car, so I am bias lol.
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Old 04-06-2016, 10:27 PM   #496
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The 3576 basically keeps breathing up top . The 3576 has a 35r exhaust wheel vs the mismatched 3076
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Old 04-07-2016, 12:34 AM   #497
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Quote:
Originally Posted by Joshwrx04 View Post
The 3576 basically keeps breathing up top . The 3576 has a 35r exhaust wheel vs the mismatched 3076
I understand that is the common statement used with these two turbos. But I have yet to actually see it shown with real data. Maybe I'm just not pushing mine enough yet to have found that "choke point" in flow, must be a sign I need to turn it up a tad. Lol

If you come across a link to those back to back tests toss me a PM. Please.
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Old 04-07-2016, 01:08 AM   #498
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I'd love to see some comparison data too. I'm probably going to buy one or the other in a year or two. I get that the GTX3576 makes more power, but the GTX3076 makes enough for me and I'd rather not have to rev any higher than I already do (GT3076) to get into the happy zone.
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Old 04-07-2016, 03:18 AM   #499
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The GTX3576R has a better blade speed ratio match between the compressor wheel and turbine wheel compared to the GTX3076R. So, that results in significantly better turbine efficiency which allows the 3576 to spool about the same as the 3076 despite having less turbine pressure ratio to power the turbine. Of course, the bigger turbine frees up a lot of power up top. On the order of 50whp maxed out.

Here's some data from an Evo:
http://www.evolutionm.net/forums/evo...-gtx3576r.html
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Old 04-07-2016, 03:44 AM   #500
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Quote:
Originally Posted by spdracerut View Post
The charts are interesting, but not convincing, since this was a catted 3076 versus catless 3576.

Also interesting, but not convincing:

Quote:
What this means, is that UNLESS you are going past 500 WHP, the smaller GTX3076R turbine will spool sooner, respond faster, better transient response and quicker torque upon throttle movement. The GTX3076R will be much more "peppier" to drive around.

[....]

I have had many occasions, on all sorts of cars and engines, between the GTX/GT30R vs GTX/GT35R... Regardless of what the dyno says, the moment you drive the car you'll notice the GT35 turbine is a much bigger turbo if everything else was identical on the motor.

- http://www.evolutionm.net/forums/evo...l#post10037445
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