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K16 v K24 the "lag" issue

 
Old 10-18-2007, 12:58 AM
  #46  
Bill S.
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Originally Posted by Jean View Post
Bill
I have zero consideration for lag as I simply don't believe it means much if anything, unless the turbos or tuning are really unsuitable, the 6th gear test is meaningless from a practical, however the only one that really shows boost onset threshold and it's impact, which is the subject of this thread.

None of us would be accelerating from 2k RPMs in 6th gear if he was looking for performance anyway. So this is only interesting as far as data is concerned.
Jean, I completely agree with you. Check out my new Got LAG? thread. That may make it more interesting.
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Old 10-18-2007, 08:25 AM
  #47  
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Originally Posted by Jean View Post
I agree with you that this test is really meaningful to measure "lag" only if the 2 993TTs have similar displacement and compression.

I have zero consideration for lag as I simply don't believe it means much if anything, unless the turbos or tuning are really unsuitable, the 6th gear test is meaningless from a practical, however the only one that really shows boost onset threshold and it's impact, which is the subject of this thread.

None of us would be accelerating from 2k RPMs in 6th gear if he was looking for performance anyway. So this is only interesting as far as data is concerned.
For a car used purely as a road car I have to disagree with the above.......

Engine flexibility is what makes road cars "nice" to drive and contributes massively to a superb driving experience in a daily driver -It is always an objective for Reinhold Schmirler (Mr RS) to produce the widest possible torque curve on the road engines he builds. With my engine it meant on and off the dyno many times whilst different cams and timings were tested, apparently he would lose bottom end and gain top and vice versa until he was happy with the outcome. I believe Ruf also works on this principle.

We call it "lag" which implies it is ALL about the turbo, the sizing of the hot and cold wheels, the flow within the housing, the ZC etc but in reality "lag" comes from the whole of the engine build, matching of components and the ability to test their function (that expensive engine dyno) so it replicates what happens on the road.

Building engines like this is very expensive (due to the componentry and development time) and in a world where (uninformed) people focus purely on a peak power number, it is much misunderstood and often gives rise to people's incredulity at the huge sums $$$$$$ being asked by the best Euro tuners for "hp" which is available in the US for a fraction of the price. The numbers I gave show how this approach translates on the road .....

It would be great to get some more numbers from other RLers -I'd like to see what a well mapped K24 could do ?

BTW I checked the actual revs for the 80-120kph using GPS and rev counter and they are as follows:
3rd gear 3659rpm -5400
4th gear 2950rpm -4250
5th gear 2200rpm -3430
6th gear 1750rpm -2650
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Old 10-18-2007, 09:40 AM
  #48  
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Originally Posted by TB993tt View Post
BTW I checked the actual revs for the 80-120kph using GPS and rev counter and they are as follows:
3rd gear 3659rpm -5400
4th gear 2950rpm -4250
5th gear 2200rpm -3430
6th gear 1750rpm -2650
Great info! If we get the revs for 5, 10, 15, 20, 25, 30, 35 and 40 mph in 1st gear, you can clearly see the "lag" vs. rpm from my 5-60 mph run by looking at the longitudinal Gs. You can do this in other gears also, but the 5-60 mph run gives a consistant rpm range, and also gets the real low rpm. You don't really need to shift into 2nd to get to 60. I only included that so we can get some performance data at the same time, since 5- 60 mph times are widely published in the US. That is, many people care about the "stop light" performance of their car.
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Old 10-18-2007, 10:23 AM
  #49  
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But traction plays a part in a 5-60 time which is a variable that's more difficult to control. In that way the 8-120 test is more consistently repeatable.
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Old 10-19-2007, 01:46 PM
  #50  
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Originally Posted by TB993tt View Post
For a car used purely as a road car I have to disagree with the above.......

We call it "lag" which implies it is ALL about the turbo, the sizing of the hot and cold wheels, the flow within the housing, the ZC etc but in reality "lag" comes from the whole of the engine build, matching of components and the ability to test their function (that expensive engine dyno) so it replicates what happens on the road.
TB, I agree with the above. Of course having a responsive engine is a major win on a street car, where I disagree is that this is related to lag... Lag AFAIK is how early boost comes on. In anything less than 6th gear, the difference between different turbos is offset by the tuning setup... i.e. in your case, the reason your car is so fast in 3rd gear, is not because you have less lag than a stock 993TT, but because you have a very well built engine, that pulls very strongly in those RPMs and goes up to 1.2+ Bar etc etc..

Where real lag comes into play, is when you look at your 6th gear run. This is a much more indicative measure of lag. The strength in your engine is that RS Tuning has been able to achieve very little lag for the big turbos that you have, and this was done through state of the art tuning, smart engine building, and components. Like for like, a car with your turbos would have gotten a 10 second run most likely. This is why I am saying turbo lag is not that important, unless it is seriously bad. The real measure of it is in 6th gear at 2K Rpms, any lower gear performance below 6th. is rather related to overall engine build, boost limit, etc.. In all the other gears, boost is already present from early RPMs, so we are not measuring how long it takes boost to show up (lag)
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Old 10-19-2007, 02:25 PM
  #51  
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Originally Posted by Jean View Post
Latest update:

997 GT2 (530 BHP) 80-120kph:

4Th: 3.6s
5th: 4.8s
6th: 7.4s

It has taller 4th-5th and 6th gearing than the 996 and 997TT, yet look at those numbers!
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Old 10-20-2007, 04:13 PM
  #52  
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I've been thinking about a simple approach to test the debate between the K16 vs K24 turbochargers. I think that while looking at car vs car is good, the ECU has a large impact on improving the performance.

One approach would be to take one car and structure the road tests 0 to 60, 5 to 60 or 60-130.. Keep the car and the tests consistant..

Start with mounting K16's on the engine and install a stock ECU.. Run the battery of tests.. (mount the 450HP ECU and run the test as mentioned below before taking off the turbochargers)

The mount up K24's on the same engine and keep the stock ECU in place.. Then run the same tests..

While the K16's are still mounted install the Porsche Motorsports 450HP ECU and run the same tests..

When the K24's are mounted install the Porsche Motorsports ECU in and run the same tests..
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Old 10-22-2007, 05:47 PM
  #53  
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Fellas..what an incredibly insightful and helpful thread..I'm contemplating putting K/24's on my 993TT w / GT2 body work ,also cat by-pass,and fabspeed muffler by pass..
And have been wondering what ECU modifications would benefit the greater breathing capaity of the
larger compressors,,either Motorsport,GIAC, or FVD?
Not yet at that stage but completing some prior projects,but it awaits in the garage! Thanks Bert
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Old 10-24-2007, 12:52 PM
  #54  
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Originally Posted by budge96 View Post
Fellas..what an incredibly insightful and helpful thread..I'm contemplating putting K/24's on my 993TT w / GT2 body work ,also cat by-pass,and fabspeed muffler by pass..
And have been wondering what ECU modifications would benefit the greater breathing capaity of the
larger compressors,,either Motorsport,GIAC, or FVD?
Not yet at that stage but completing some prior projects,but it awaits in the garage! Thanks Bert
Bert, thanks for saying thanks
My only advice would be to buy the blowers AND the ECU program from the same vendor and choose one who has a solid rep.....
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Old 10-24-2007, 01:20 PM
  #55  
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Budge96: My car (Frank) is set up pretty much exactly as you describe with the FVD setup turbos and ECU. If you would like to take a drive you are welcome. (Assuming it has not sold before you can make it by.)
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Old 06-20-2013, 09:44 PM
  #56  
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Old thread bump.

Does anyone know what is the intake inducer diameter of the K16 turbo and the intake inducer diameter of the K24 turbo that were equipped in the 993tt's?

I have a feeling that my car is equipped with K24's and most likely from factory.

Thanks,
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Old 06-21-2013, 07:28 AM
  #57  
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If you have standard factory installed K24s then the part number plate on the turbos should reflect this, as would the part number on the ECU and the option code sticker in the service book and under the front lid.
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Old 06-21-2013, 02:34 PM
  #58  
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Originally Posted by Felix View Post
If you have standard factory installed K24s then the part number plate on the turbos should reflect this, as would the part number on the ECU and the option code sticker in the service book and under the front lid.
I have photos of the current turbos in my car (didn't see any blue or any other color plaque stamped just random numbers from the casting).
My car has the 430cv power package option. I do have a photo of the engine ECU as well. However my car is a euro spec and my service book didn't come with any sticker like the US specs Porsche as I have seen through the internet.

I suspect I have K24 because of the lag I feel (no tmy first turbo car) and the very little info I found on the web about the size of the inducer for the compressor side of the K16, my actual turbos are arround 3mm +/- bigger.

EDIT: My right side turbocharger is stamped on the compressor housing the following number: 5324-101-5075. The I google itand found these links:

http://www.stwtuning.de/turbolader/p...1-2005/a-6986/

https://rennlist.com/forums/993-turb...hargers-3.html

Anyways, to be 100% sure, I would need to measure the turbine housing. I might do it soon as I need to replace some seals arround that zone.

Last edited by DiegoR; 06-21-2013 at 04:38 PM.
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Old 06-22-2013, 05:16 AM
  #59  
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Blue plate with info on it, this one has "K16" on first line
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Old 06-23-2013, 05:44 PM
  #60  
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^^

Triend to locate the ID tag in my turbos but couldn't find them. I wonder arround what RPM kick the turbos in 2nd gear going WOT from say 2000 RPM. Mine does kick about 4500-4700 RPM.
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