Jean

TB

I am impressed at how much effort and money you have put into this, to try and get the best available out there. Thanks for your feedback, I, and I think the board appreciates it.

These turbos seem great for street usage and autocross or DEs, which is what 90% of the buyers will be using them for, and I would be the first one to buy them if that was my intention.

The question to Kevin is whether trying out the modifications based on the K24, which I know he dislikes, would get you anywhere close to the 550hp. Some guys on the board have made claims of 600hp or thereabouts with hybrids while having amazing low end acceleration .

So what is your next step, GT BB Garretts?

TB993tt

Hi Jean
I have really enjoyed the somewhat expensive "experiment" and I almost pulled the trigger on getting the ECU remapped for the K16s but after enjoying the Autobahn I realised that yes I do want that massive top end (5500 to 7000rpm) rush. People must realise that we are comparing the Stage 3s to RSK24s NOT regular K24s, the RS ones are very different so I believe that the Stage 3s will indeed be significantly better all round than regular K24s. The only problem that I have and will continue to have is the inflated hp claims eg Geofrey's assertion that he can get 650hp with Stage 3s and a "built" engine
Kevin will go mad over this (and if I had more time I would have got him to build me something else) but I have persuaded (yes I know this seems ridiculous, but RS do not want the work, they are too busy on their race engines) them to look at other options for me.
I will probably still only get mid to high 530PS - but I know that this will be real sustainable hp with a huge area under the curve.
I am also having the manufacturer of Cargraphic Exhausts make me a one off freeer flowing rear muffler set since the new export ones I put on were worse than the TUV ones

John H. in DC Area

Fascinating information, TB, thanks for sharing.

Viperbob may be on vacation, but I believe he has some K24's ZC'd, ceramic coated, and otherwise massaged by Kevin. I'd be curious to hear what HP/TQ they are putting out and what the curve looks like. Perhaps he'll chime in when he gets back.

Also, post more pics of your car when you get a chance, I can never get enough.

mkhn

In a quick conversation with Viperbob, he said he was probably reaching the limit of reliability with stock engine components while pushing the 600hp level using K24 hybrids(K24 turbine with K26 compressor). I'll let him fill in the details, but being that his car is so light, I think he mentioned that the lag wasn't that significant compared to K16's in previous posts.

ScottMellor

TB:

Nice job man! I know you dropped some coin on figuring this out. Thanks for sharing.
FWIW, I drove Addisons ZCd car and my car back to back last week. The ZC is probably a better street-only option because of the insane low down acceleration.
Interestingly, my tech, Mike Schatz, brought up the heat limitations of the K-16 when I was quizzing him about them.

TB993tt

Scott
Thanks to you (and all other posters) for the encouragement.
Your comments about street application are spot on - my car was nicer to drive with the ZCs, quicker throttle response and it didn't feel noticabley slower even with "only" 671NM and 471PS - It was the Autobahn experience which I think swayed me away from keeping the ZCs - whilst they could not be described as slow, accelerating from 130 to 180mph time after time, they didn't rip like the K24 based units did. I think my "out of calibration" Butt Dyno showed that at speeds under 120mph, 50hp is difficult to detect as these levels

K24madness

TB very impressive work! Sorry the results were not what you expected. I for one like the K24's. I don't mind the lag since removing the cats. I would love to go even bigger on the compressor side like you & Bob did with the K26 wheel.

Sorry this experiment had to come at a significant cost to you!

Maybe we can convince Kevin to do work on my K24's now.

Geoffrey

TB, I have never shared inflated results, what I posted was a RWHP dyno sheet with a stock 993 engine running Kevin's stage 2 turbos at .7 bar of boost (less than stock). And I have not discussed his stage 3 turbos since I have only had experience with his 2, 4, and 6 turbos.

TB993tt

Er.... maybe not results but:

If I developed the 993 programing for a motronic ECU for model year 96 and 97 with Kevin's turbos how many would be interested? I would potentially be willing to do the following:

Stage 2 - nonZC & 550hp at under 1 bar of boost (stock internals)
Stage 2 or 3 - ZC at 650hp (modified internals)

Jean

Geoffrey

If I recall correctly, you were able to get 560 hp at 0.7 Bar of boost on the stage 2 (maybe my recollection is wrong and I apologize). And standing where I am today, and based on TBs facts, I have a difficult time understanding it.

I have full trust in you and you know it, but something here is not working. I recognize the capability of Motec however turbo heat and CFMs cannot vary that much between a Motec and an RS tuned Motronic, who I consider to be among the best, with optimized AFRs and a good I/C.
What could be the explanation? I am only curious to understand.

Geoffrey

Thats right, I might be willing "to develop" which implies there is work to be done...

I'm not disputing your results, only trying to understand the test conditions.
a) Can you show the boost curve
b) Can you show the AFR
c) can you show the hp/tq graph?
e) What were the intake air temps
f) What was the back pressure and EGT before the turbo
g) What was the injector duty cycle
h) How long were the runs or were the tests performed steady state?

There is more involved than just the turbos.

ScottMellor

I believe Mr. and Mrs ZCAT have ZCd K-24s on their TT. Maybe Bill can chime in on them.

Geoffrey

Jean, it was more like 540fwhp corrected using a 22% AWD drivtrain loss or 421awhp. You can use whatever correction factor you want (a5 15% loss it is still 495hp) so you make up your own number. It was at .7bar held consistent throught the RPM range. I know that the stock fuel injectors at stock fuel pressure reach 85% duty cycle somewhere around 440hp and with 5bar somewhere north of that. I don't believe they will be under 85% at over 500hp. I was running 72lb injectors at stock fuel pressure so there was future support for 700+hp. The turbos were stage 2 non ZC.

Jean

Geoffrey

Thanks for the clarification, those are very impressive numbers.

In TBs case, injectors are not an issue as a limiting factor at these levels with ZC but his power curve implies CFM threshold, heating up the turbos and dropping performance, assuming a properly mapped ECU.

It would be very interesting to see a chart with K24S ZC, I cannot believe that no one who has them does not have a dyno run at this point they look to me like a better alternative.

Geoffrey

I don't think I could make any opinions about TBs run because there has not been enough information provided.