Generally speaking, that is a rule of thumb, and an assumption. However, this may not always be the case, and the testing I've seen indicates TS may provide an exception.


Fair enough, but that suggests that the two TS EVOs I've driven to date either have spectacularly excellent manifolds (thanks Walker), and/or every open T3 housing EVO I've seen with a GT3076R or larger has crappy manifolds. My point is, if you've driven enough open T3 cars to know what to expect from driving a particular turbo size, you'll recognize the difference in driving the TS equipped car as soon as you pull out of the driveway. This has been my experience to date.



This isn't really accurate.

TS makes a significant, unmistakable improvement in ALL rpm ranges and ALL throttle positions before max boost. The larger the turbo, the larger the area of operating range this covers. I know this, as feel the effects of TS in 90+% of my driving time, all of which is spent in off-boost driving (I have a 75 lb/min turbo). I can't tell you the results of the max-boost operation, only because I am not yet finished testing it.

IF you were to drive my car, you would be amazed at the part throttle response and torque. It feels remarkably better, quicker, and more responsive than any of your open T3 35R cars, despite the fact that I have a larger turbo and T4 TS turbine housing. This isn't speculation, and it is the first comment made by everyone who's driven the car. It isn't because there is anything 'wrong' with regular 35R setups, and it isn't because there is anything unusual about my car. It's just the difference between open and TS, and anyone can and has been able to tell the difference - right away.

 

This is a great discussion and the reason of my post was to show the results we had testing the GT40R TS vs. OS design. Like I've said I do agree that the TS will spool quicker but at the sacrifice of top end power. Ted's question is the one we need to answer. Will going up on A/R ratio of a TS give the top end power of an open scroll while spooling quicker? For the street a GT35R and a GT30R will give similar power on pump gas, maybe only 25whp difference, now the spool up with be quite different. I would like to do some intensive testing but it would be very time consuming and $$.... we'll see, I'll do some thinking and see if this would be feasible.

 

I'm sorry, I really should have put it that you keep neglecting to look at turbo response time...you are only looking at the turbo is already spooled state.
Your comparison of time to spool vs. time spooled (making power) isn't a far judgement as this kit only benefits times you are making more power SS than TS.

SO if the TS theoretical spools faster (time, not RPM) you will compound your acceleration. But this next argument is theory based as we don't have a comparison of turbo response in time.

as you know for road racing, exit speed is key as you then exponentially cover more distance in the same time as a car accelerating as the same rate.

For the road racer you then look at the time it takes to spool to carry out maximum exit speed and being back in the powerband. Then you have to weigh the trade off of off corner turbo response/torque and the trade off of peak power on the straightaway.
I wouldn't wouldn't trade off-corner torque for a 20 whp power gain.
Now, all this is void if you have a good driver who can brake boost while cornering or if you run antilag.

 

Yes but not everybody brake boosts and runs antilag unless your driving a full all out race car like the Le mans cars or a formula prepped car

 

You should not equalize timing and boost. You should maximize each tune, other wise, you're not comparing each set up at its fullest potential. What value is there to that?

 

ding ding ding...I'd agree. Along the same lines as my first reply talking about the off the shelf turbo kits...compare what is out there. Not making equal length and radius manifolds. But I guess the point it to show the true differences in the exhaust housings alone.

 

I disagree, I would keep boost and timing the same and equalize the A/F ratio. If one housing is flowing more and making more power at high RPM's this will reduce backpressure. This in turn will reduce the amount of end-gas in the combustion chamber, which theoretically should allow you to run a little more timing. But also the reduced BP increases VE so you might need to run a little less timing... see where it gets complicated? You would need in cylinder pressure analysis to monitor pressure spikes (knock activity) to really bring each tune to it's max potential, big $$$ . Using a factory knock sensor at this level would not be accurate enough.

 

Martin,
Of what value is any test where you are not maximizing both set ups? I'm not really interested and I doubt many here would disagree. This only serves to obscure the results as one set up or the other will not be optimized. Optimize both setups and post the results. You guys do this every day and I have no doubt you could do a good job of approximating an optimum tune on both set ups. You tune every day without sophisticated knock dectectors, so why let that deter you here.

If you can get more power by running more boost and/ or timing with one set up over the other, that is exactly what we want to know. You or anyone that does the testing should not limit either set up.

Robert

 

ill respond later, but this test isnt very conclusive... there are plenty of points to touch upon.

unless i am mistaken, both AMS and Ivan (AMS' head tech) are both in this thread saying twinscroll will spool earlier but in exchange for that earlier spool, there will be a power loss at high RPMs (i would agree with this statement under certain circumstances/test conditions, yet vehemently disagree under others). Additionally, they mentioned that twinscroll is not for drag racing...

edit: doesnt AMS and Ivan run twinscroll setups on their drag cars????

 

they said not anymore.... they use to

i wish you would respond soon, the entire community is waiting on numbers and curves from your new kits.... my bank account waits in the balance lol

 

Agreed. It's always nice to see something new come along and challenge the existing hardware for the new standard.

 

sorry man i just flew into phoenix this morning, have to get caught up on a ton of stuff, i promise ill take care if this by the time i leave tonite, but it might not be until 1 or 2 am

 

Did a bit of research

HKS CT230r EVO : HKS GT3037s (Open Scroll)
Cyber EVO : ApexI RX6 (Open Scroll)
JIC/Hankook Silvia : GT3076R (Open Scroll)
AMS TA1 EVO : GT35R (Open Scroll)
JUN Hyper Lemon EVO V : TRUST TD06SH-25G (Open Scroll)
Mines R34 Skyline : Twin HKS GT25/30 (Open Scroll)
Zero Sports STI : IHI RX6 (Open Scroll)
Nagisa Auto R34 : T-88 33D (Open Scroll)

 

ill have numbers and all the goodies soon on my kit

93oct
c16fuel

i just am having an ignition problem im trying to fix befor its finished tuning.

 

A good twin-scroll vs open volute test would also entail re-tuning the car for each setup--beyond fuel & spark, cam timing would be rejiggered too.

This will be necessary to reflect the differences in blowdown characteristics between the two setups. Once the wastegate is open and you're at full boost, TS will show higher average backpressure due to lower turbine efficiency, but the cylinder on its overlap period will be isolated from seeing the exhausting cylinder's peak pressure pulse during blowdown. Hence the need to revisit cam selection.

Basically a TS housing that has the same "flow swallowing capacity" as an otherwise similar open volute housing will exhibit a (small) penalty in map efficiency. This reduction in efficiency results in the higher average EBP I mentioned above.