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No......yours does feel like a 600HP turbo down low. Just because it is Stao's special recipe and is actually quite good down low doesn't mean it can't be better. If you add his Extra Special Recipe © to it, it will be even more good down low. That's what he was saying.

I mean, lets' be fair......I'm not rubbishing the turbo you have, because I know full well that it is a good thing. The point is that it must spool a bit slower than the stocker, and the stocker is a 400HP turbo. An old, crappy 400HP turbo, but let's ignore that aspect of it. Stao's statement was,"Add VNT to your big turbo, get stock turbo response at low rpm, add big grin to face."

Makes more sense now you edited it :P

No, Stao was right when he said "all". A 600HP turbo will feel like crap at 2500rpm. That's what he meant. His 600HP alpha turbo will feel like a 400HP turbo at 2500rpm, but will be capable of also doing 600HP.

This is ridiculous. His turbo is not a 400hp turbo at any point - it is a 600hp capable turbo limited to 400hp due to measures taken to spin up the 600hp capable wheels a bit quicker. Its still a 600hp turbo, and I am dubious that when it is in 400hp mode it will match a "conventional" well matched 400hp turbo. There is no standard behaviour of a "600hp" turbo, for example an old T3/T4 versus an HTA3076 will have QUITE a different driving experience.

On the topic of the 600hp thing - I have asked twice now how these perform on pump gas. Any answer?

I didn't say it was a 400HP turbo at any point. Said I agreed with his statement that it "felt" like a 400HP turbo.

So, further disclaimers. I haven't driven his turbo so I don't know what it feels like. I was merely interpreting his statement for those who missed the point Stao was making. I also agree that "600HP" turbo and "400HP" turbo are vague terms. But I think it's fair to restrict our understanding of these terms to be consistent with the turbos that Stao handles, thereby negating the need to drag up vintage turbos from the past, or 600HP turbos that do so at very low pressure ratios or very high pressure ratios etc etc.

Stao's statement is that simply that VNT makes it feel like a smaller turbo than it really is when at low revs.

This is ridiculous. His turbo is not a 400hp turbo at any point - it is a 600hp capable turbo limited to 400hp due to measures taken to spin up the 600hp capable wheels a bit quicker. Its still a 600hp turbo, and I am dubious that when it is in 400hp mode it will match a "conventional" well matched 400hp turbo. There is no standard behaviour of a "600hp" turbo, for example an old T3/T4 versus an HTA3076 will have QUITE a different driving experience.

On the topic of the 600hp thing - I have asked twice now how these perform on pump gas. Any answer?

SS2 is a well matched item to the HTA3076. You can run a comparison to that using both the standard BB and CBB Alpha version. The HTA item has identical boost plot to the BB Green standard version. Add Camshaft and more boost it will match that HTA3076 power.

If you are wondering what HTA3076 is like on SS Alpha housing with stock cams, then you are looking at it now:

(SS2BB V SS2 Alpha CBB)

374695.jpg

374694.jpg

SS3 Alpha is a Duel ceramic roller bearing billet turbo, I've mentioned it is physically larger then the HTA3076 item. That is why it made more power on a less modded car. As if you are comparing a 600HP turbo to a 500HP turbo.

Some big claims, be good to see how they pan out - I got curious and plotted what I have available so far with Excel to get an idea of where everything is,
I have tried to be reasonably accurate with this, but it is Friday night and I haven't got ultra precise with my measuring so if people get curious they are most welcome to check out the dyno plots themselves and compare the points (I chose 500rpm increments from 3000rpm->7000rpm) and draw their own conclusions or correct me on the plots, if indeed my numbers are definitely wrong (this means that it is agreed to be) I can update the chart and resupply it - I do this for data collection, as I like data and like the stories to be presented with accuracy.
Other points worth taking into consideration when looking at this chart:
- The HTA3076 peaks at 28psi and drops back to 24psi, while the SS2 is holding around 22psi and the SS3 around 24psi steady. This gives the HTA3076 an artificially high midrange advantage in those plots and isn't so much of a representation of the turbo so much as just how the cookie crumbled. Again, when more dyno plots show up (ideally a flat 24psi one) I can redo the chart for a better comparison
- I am unconvinced that the Mainline the HTA3076 result was run up on reads the same as the Dynapack - I don't feel it is a huge difference, but when you are talking a few kw those kw mean a lot. I've added a second HTA plot which scales the numbers from the Mainline dyno plot by the amount I SUSPECT covers the difference between these two dynos. I came up with the numbers I used to get the difference between these dynos well before any of these results came up, so I could make sense of comparisons like this - and also predict results (which I did within a few kw for the HTA3076 result).
I have added the numbers as directly from Mainline dyno as well so people can come to their own conclusions, though FWIW remember the HTA3076 is running aftermarket cams two which means that there is some advantage there - which means the HTA result has a bit of advantage, though that also means that anyone indicating that my dyno scaling (which results in the HTA and the HG making similar power on similar boost) is off I'd like to know reasoning for it - including how a stock cam RB25 should be able to make more power than a cammed RB25 on the same pressure ratio... would be awesome to see the HTA result on a Dynapack actually, I don't really enjoy or relate to rolling road dynos (hence me working out how to compare it with a Dynapack :) ):

Near400kwRB25Turbos.png

Be interesting to see what other people make of it, to me it seems the SS2 Alpha has a slight advantage over the HTA3076 (and others) in spool but at least in this comparison falls short on power. I don't know if this was it run to max on the setup it was on or not, and hard to say how much it will add with cams but I've just plotted what I can find.

The HTA seems to be very similar to the SS3, if not a little quicker coming on but it does like a bit like it could possibly hold on slightly more at the top end than the HTA. All in all, the VNT trick seems to help nicely - though the HTA is an ultra potent turbo for one that doesn't use any mechanical intervention

Where the vnt have variable Vaines/nozzles to guide air at the turbine

Which can be controlled to open and close with a actuator

Fnt nozzles are fixed so can't be controlled and are put on certain spots on the turbine housing to guide air on the turbine to help it spin quicker and faster

Driving my current turbo which is atr28g2 with fnt it's like chalk and cheese compared to kando td05h18g

Bottom end response is so much better seems to start spooling straight away on any throttle

Seems to pull as good as the td05 up top on 18psi vs atr28g2 is only on 15psi till I get it retuned maybe 22psi if the injectors can cope

Bottom end and light throttle is uncomparable

Well i finally got my car retuned with the fnt atr28g2 sr20 vs kando td05h18g there is abit of difference downlow full boost by 3800rpm 25psi

Can't wait to run it at wsid hopefully 11s now I got et streets

Edited by hy_rpm

Near400kwRB25Turbos.png

^^^^

That is a good effort. It doesn't contain enough information. There for I've added some to make this comparison more meaningful.

Near400kwRB25Turbos2-1.jpg

Edited by petero'nell
Some big claims, be good to see how they pan out - I got curious and plotted what I have available so far with Excel to get an idea of where everything is,......

The comparison is nonsense. if a set of cams adds in an additional 35kws as usual in this sort of power level then you should plot the HTA result with a 9% decrease in power as a more accurate comparison. Or add 9% of extra power to the SS alpha results to make better of a sense.

Plus I've already collected enough results here to prove the minor differences between Trent hub dyno vs a roller dyno. The latest result Hy_rpm provided have again proven the same thing.

Because all my current results in reference to particular turbo profiles are all based using factory cams, changing in cams will affect the consistency in profiling data, making outcomes in alterations more difficult to predict. After all 90% of us are using more of a standard Rb25det without cams, which I rather focus my target on.

At moment I'm concentrating in bolton Alpha series including highflows. Making a bolton turbocharger internally gated with stock manifold more powerful then what it currently is while not getting larger turbocharger's lag. After that I will be happy to install some cams for the maximum capacity of our turbochargers, which you can compare them with.

Fair enough, been a long week, and I didn't explain my point very well - so it being missed is easily understood. What we can agree on (from your post) and what I was partly trying to get at is you CAN'T compare results from other setups on other dynos, so I guess you can't say yours is supposedly as good or better performing than another product when there is no fair and even testing of both in a like situation (ie, same or at least equivalent car, dyno etc). Suggesting differently would be hypocritical, and essentially making false claims - which is not one of my favourite characteristics, especially from someone I'd consider buying goods from.

Long (and I mean very long -I've been following this thread since it was around page 20) time lurker first time poster - I'm really excited to see the VNT results, I've been waiting ever since you expressed interest in developing them :-)

One thing I'm curious about that I'm really surprised hasn't been mentioned yet is if you have dropped your exhaust for any recent dyno tests? 400rwkw from the SS3 alpha is a good result on 24psi in my opinion but I can't help but wonder if a 3" cat back exhaust is holding it back somewhat.

Fair enough, been a long week, and I didn't explain my point very well - so it being missed is easily understood. What we can agree on (from your post) and what I was partly trying to get at is you CAN'T compare results from other setups on other dynos, so I guess you can't say yours is supposedly as good or better performing than another product when there is no fair and even testing of both in a like situation (ie, same or at least equivalent car, dyno etc). Suggesting differently would be hypocritical, and essentially making false claims - which is not one of my favourite characteristics, especially from someone I'd consider buying goods from.

well I didn't claim "better then" a specific competitor's goods. How ever by understanding what a Garrett GT3076 is, and worked on many of them, what I'm saying is that the SS3 is a Bigger turbocharger in both compressor and turbine side, SS3 does NOT have a 60mm 84T GT30 turbine end with a fancy looking compressor wheel.

Question is what is the limitation of the GT30 turbine end? For example you can run a huge compressor wheel making some thing so called 3082, how ever it will never produce as much power as a 3582. I believe the billet compressor wheels are there to fill up the gap between the original 76 and 82mm compressor wheels, pushing towards the limitation of the standard GT30 turbine wheel.

In the combination of two wheels, the maximum efficiency is reached when the limitation of either one out of two wheels is reached. From observations in results gathered from Trent's dyno, Based on a stock Rb25det using factory cams on E85, the limitation of the 60mm/84T GT30 turbine wheel is 380rwkws, while the limitation of the 56T 76mm compressor wheel is 360rwkws. There for the billet compressor wheels come in, full filling that extra 20kws gap. The SS3 compressor (larger then 76mm) has been fitted on to a larger custom grind turbine wheel that is bigger then 60mm with bigger exducer.

Why is the VNT turbine housing better. For example .82 size turbine housing is only required to not chock the engine at 6000RPMs on wards, hence most Rb25dets reaches it peek power between 7000~8000RPMs. I have no need for such a large turbine housing when I'm driving on 2000, 3000, 4000 or 5000rpms. So I have made a turbine housing that is in .40 A/R upto 3000RPMs, .60 A/R from 3000 to 5000RPMs, and .82 A/R from 5000RPMs on wards. Even thou I do have a massive 600HP turbocharger, it still drives as a tinny turbo down low and I'm not missing out any peek power up top.

My engine is no differ to a stock engine apart from Stronger pistons and valve springs. The engine building process is fully documented and photographed in this thread. The pages could be found through index page 1. Neither parts would stimulate the power to boost ratio compare to a healthy standard engine.

I can check Trent's dyno data, for a base graph of a GT3076 on a similar setup, while working out a percentage difference to manipulate a more accurate comparison just for curiosity's sake.

What's the VNT turbo like to drive in first, second and third with the fact that it acts like its a different A/R size in lower revs. I suspect a lot of difference to the other turbos?

It doesn't have that flat bit in low rev and low gears, which usually is there with a large turbo, and the turbo comes a live with very light throttle. Specially the SS2 alpha, it felt very close to a factory turbo on road.

I don't think It would be easy to explain how the car is to drive. I can't imagine what it would feel like to have that sort of response and power

Would love to take one for a drive :P Would feel unreal I bet

I'll just see what mine feels like for the moment anyway, should be fast enough once E85 is available on pump here.

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