I was talking to a turbo company over here in the U.K. and this is what they offer written below.

I am no turbo engineer but going on the info in the link there does not seem to be to much of a difference or is there?

https://www.6speedonline.com/forums/...size-flow.html


Need turbo geek help please.


"To upgrade we take the existing K04 and fit a bigger, better flowing 35lb/min KO6 Billet compressor wheel and CNC machine the compressor cover to match. We also fit our motorsport bearings and seals which give the unit added strength over standard. We cutback the Turbine blades and then balance and blueprint the units to motorsport tolerances. This upgrade will allow the unit to flow more air at the same boost pressure – also remains direct fit. The standard VTG Wastegate system remains the same as standard.
K06 Billet wheel features a 46mm Inducer and 59mm Exducer."



If I go by other info I have read then 35lb/min x 9.5 x 2 = 665bhp? ( but thats running them at the limit so they would be good for less power?)

 

There is way to little info on vtg upgrades online and I see vendors prefering ppl to PM or call them.

There seems to be several compressor side sizes 65-68mm but little info on turbine side work. I am also thinking about a vtg upgrade in the future and hope this improves by then or I'll stay stock...

 

Yes well it would be great to see what people think of these turbos I have mentioned.

I don't think much can be done to the turbine side from what I understand but I could be wrong!!!!

 

Maybe the whole VTG inlet valve setup makes actual upgrades impossible?

 

An OEM 997TT VTG turbocharger has a 60mm measurement at the exducer and a 43.8mm measurement at the inducer (on the compressor wheel). It's also a 6 blade wheel stock.

Our 68mm VTG's upgrade to a 7 blade billet compressor wheel with a 68mm measurement at the exducer and 46.9mm at the inducer. They are rated about 475 HP each.

There's not much to be done to the turbine wheel. In fact, most times it's clipped to prevent overspinning of the compressor.

Hope this helps...

 

Hey Tom it's been a while!

Can you make any comments on the turbos I have mentioned.

 

You should contact Owen Development in the UK...:

Xxxx,

I apologize, but we do not sell our proprietary parts individually. You may want to contact the guys at Owen Development in the UK, they would be much closer to you and they do have access to our parts and I am sure they could help you with any application. If you have any other questions, please let us know.



Thank you,

Amber

Sales Team
Forced Performance Turbochargers, Inc.
972-984-1800
www.forcedperformance.net

Forced Performance is the company that makes those HTA turbine wheels. You may also find this thread: http://forums.rennlist.com/rennforum...ngines-29.html helpful in some ways.

 

Thanks for the info, since your webpage is still down, how much would a set cost (shipped to EU)?

 

Our 65mm VTG's are $5495 (including core exchange of your OEM turbos)

Our 68mm VTG's are $5795 (including core exchange. We also highly recommend the use of our carbon turbo inlet pipes with these turbos)

Shipping would depend on your location.

 

Thanks for the info.

 

Some of the terminology they're using is strange to me, to be honest. "K04, K06"....those are terms I've not heard before when referring to Porsche OEM VTG turbochargers. Could be something proprietary to them, or parts they're using from another company, or simply a different terminology being used to describe the same thing as us lol. KO4 I've heard used before in the Audi world, as the factory B5 RS4 came with K04 turbochargers, which are not VTG.

What does seem strange to me is the sizes they quote for the inducer and exducer of the compressor wheel. They're inducer size is a couple mm's bigger then stock, but they're saying they use a 59mm exducer, which would actually be smaller then stock, so I'm a bit confused. I'd have to check the Tial to see how that wheel compares to ours.

 

This is why I asked the questions as it has baffled me.

 

Tom, if I may ask and you want to answer....what max boost pressure you use with 68mm VGTs and have you measured the backpressure when on max boost at peak HP/TQ?

 

No problem, I'll answer anything I can.

On stock engines, we typically max out at 23psi with both the 65's and 68's.

On some of the 3.8L and other built engine cars we've built, we normally run about 28psi. We've run 30psi on one car...but eventually backed it down to 28, as that seemed to be the sweetspot. These are all with our 68mm VTG's.

Backpressure, is a good question...I'd have to check with the guys in the shop to see if they've done that.

 

23psi is just under 1.6bar?

what do you run stock turbos at?