Geoff,
I'm well aware that the gamma-Ti's lower density allows for a lower mismatch between compressor and turbine, allowing for higher turbine efficiency. I stated this several times in my posts. But consider how well the "mismatched" GT3076HTA and GT3582HTA work in both single scroll and twin scroll setups, as evidenced by numerous builds on this forum..

 

I think that the real next revolution will be a RELIABLE turbo with VATN technology for our cars

 

I am pretty excited for the reference for the 1: 1.08-1.15 "rule of thumb"!!! Is the long winded response ready yet!!! I hope it is not just an engineer at garrett or BW. We have all worked with atleast one dip**** engineer in our lives!!! Actually, hopefully it isn't the engineer at BW responsible for the investment casting

 

its called the u/c ratio - and i do have papers on it. i dont have time to deal with bs however

 

3582hta spools great in twinscroll, however doesnt have outstanding topend power (i believe it is turbine wheel limited). in singlescroll config it is not turbine wheel limited. the 3076hta is definitely not my first pick for a twinscroll 30R, for the same reason, it is turbine wheel limited in twinscroll config. obviously it works great as a singlescroll also

 

In regards to turbine flow being reduced on the Garrett twin scrolls, that may be way the EFRs seem like they don't run the divider all the way to the turbine wheel ?

We'll have to see how the twin scroll v-band housings that Garrett release perform, and if the run them recessed like the EFRs. Nonetheless I know of ATP fully divided T3 GT3582Rs (just plain jane ones) making near 700hp @ hubs so they can't be doing terribly bad. After seeing how well the HTAs spool in open housings it starts making me think that if you can get that balance of spool and power from them, is there any point going to the extra cost of a twin scroll "just because" with an alternative solution if at this stage there is no clear evidence that there is going to be a performance improvement?

 

Geoff,
U/C is a turbine operational parameter and has little to do with wheel mismatch, at least not directly. U/C is a function of turbine diameter, turboshaft rpm, turbine inlet temp, and turbine expansion ratio. Sweet spot is typically 0.6-0.7 for automotive turbines if I remember correctly. What wheel mismatch does is it changes shaft rpm and turbine expansion ratio to take U/C further away from the 0.6-0.7 sweet spot. Although you could in theory optimize the "mismatched" compressor/turbine to operate in that sweet spot

 

we make and sell singlescroll t3 kits all the time, and use hta turbos whenever the customer requests. if there was no performance improvement we would only sell that.

as usual - you and I see things 180 degrees differently. the conclusion ive come to is entirely opposite of yours:

 

u/c has just as much if not MORE to do with the comrpessor side!! they do interact with one another... sorry im not able to post up the documents i have here on my computer. spend some time searching sae archives and you can find some yourself

 

Come on Geoff, we are just busting your *****. I still haven't cancelled my EFR's on order with you guys so relax. Naturally you are going to have speculation after more than a year of changed dates. From an unbiased perspective(especially with myself in a 5 cylinder SS only app) the EFR's have not lived up to the hype on the dynos across the country. I sincerely hope that isn't the case as I would love to see Garrett(and others) pressured into making a stab at ceramic wheels and progresses the technology. I love BW and KKK turbos! They are OEM equipment on almost everything I work on! Even though the release of these turbos was the most epic fail of product development in recent history, I think I speak for most motorgeeks that we would love to see the product succeed!

If you have any papers on the u/c ratios, I would love to see them. PM them if you are more comfortable.. I have had a bit of turbine education in school but really would love to learn more. This would not be the first, nor hte last time I was wrong.


Cheers!
Hank

 

My bad, slip of the tongue (or keyboard lol) U/C applies to all turbomachines, but what I said still holds true

 

You won't have that problem when you understand what you're talking about instead of plagiarizing documents you find at random.

 

No doubt, you're seeing things from the point of view of a seller and I am seeing them from the point of view of a buyer.

The point of my comment which you rearranged is the comparison in price between a single scroll, single wastegate T3 GT3076R HTA versus a twin scroll twin wastegate EFR7670 for sake of arguement - not that I've broken the costs down, but given that a FP GT3076R HTA is cheaper than a twin scroll EFR7670 before you get into the added costs of an extra wastegate and more complicated fabrication... you can't really flip my comment around like that and have it make sense unless you're looking at the whole thing in terms of how much money comes your direction when someone chooses the more expensive option.

I'm not here to troll EFRs, I like the idea and believe it or not am actually neutral - as I'm here to find out what the best option will be for myself. There is no need to respond to this as I don't feel there is much more value in this thread until some results show up - so will wait until there is something worth commenting on before saying anything further.

 

My my so much bitterness... lol
Its okay to make a mistake once in a while, I didn't hold it against you when you demonstrated an inability to understand and manipulate a simple formula (regardless of whether or not you thought the model was 100.00% accurate by your lofty standards) Speaking of pretense, where's that CAD model of the EFR turbine wheel you said you'd do?

One of the unfortunate things about the internet and forums in general is that it allows trolls like this guy to ply their trade knowing that they won't have to answer for their behavior, whereas in real life you can be sure I'd have given him a nice slap to the face by now - backhanded too... lol

In any case I'm through with this loser, back to talking turbos folks...

 

Everyone wants the best stuff. And it sucks that testing which turbo is best isn't easy and straightforward, but I guess that's why it stays interesting.

Your not the only one looking for the best turbo for our needs, that's why the information and speculation in this thread is awesome.