TB993tt

Many people over the years have complained about the K24 having horrendous lag over the stock K16s.
Other than driving them it is difficult to compare from chassis dyno sheets as we all know how they can vary from one run/car to the next.
Whilst having a clear out, I came accross the engine dyno plots which Porsche published for the Euro Turbo S 450PS motor, it is plotted with the 408PS curve. Interestingly the 408PS curve is slightly different to the one in the owners handbook.
The torque curve clearly shows the laggy nature of the K24s

2000rpm K16 = 300NM K24 = 250NM
2500rpm K16 = 400NM K24 = 350NM
2750rpm K16 = 425NM K24 = 400NM
3000rpm K16 = 455NM K24 = 475NM
3500rpm K16 = 500NM K24 = 580NM
4000rpm K16 = 500NM K24 = 575NM
The curves cross at 2800rpm where the K24 then out torques the K16.
Now of course with me being in possession of some expensive engine dyno curves of my own,(done in the same way Porsche do them) It was interesting to compare my New 996tt race KKK24/26s with the bespoke RS mapping:
2000rpm K24/26 = 300NM
2500rpm K24/26 = 363NM
2750rpm K24/26 = 425NM
3000rpm K24/26 = 500NM
3500rpm K24/26 = 640NM
4000rpm K24/26 = 720NM
I guess a combination of mapping, componentry and new turbo technology means the bigger K24/26 can outspool the K24 and nearly match the K16. My question us how much is down to the mapping and how much the turbos - Kevin ?

Woodster

K24/K26 is good!
That's what I want for Christmas!
Cheers TB!
MK

TB993tt

Marty
There is more to it than the turbos. Check out the torque curves on this link:
http://www.cargraphic.de/stepone/dat..._P96Turbo2.pdf
They are RS Tuning kits for the 996tt. The first two use stock K16s and the next three the 24/26s - Whilst the lines are copied off engine dyno sheets so are probably not 100% accurate, you can see how the addition of the various components like exhausts and cams effects the low end.

LA964RS

woodster....better ask santa for some rods, ringed heads, etc. etc.

Its about 10 Xmas's worth of stuff!

but what a smile.

K24madness

I was playing on the freeway last night and noticed that boost came on as early as 2,500-2,800 in 5th and 6th gears. I have hybrid K24's (not Kevins) that have a compressor halfway between the K24 and K26's.

When I first got the car I thought the lag was horrible with the stock K24's. Things that improved it dramaticly were the cat bypasses, 10 lb waste gate springs, and a greddy boost controller. Another thing that seemed to help was adjusting the fuel ratio via adjustable FPR.

As the racers say the devil is in the details.

Jean

TB

Thanks for sharing the data. Are your numbers done on a Maha, or these are the engine dynos? In my experience, the chassis dyno (MAHA) gives more accurate (read road-like) torque readings at lower RPMs (before wheelspin can be a problem) than an engine dyno, it does not mean this is a universal statement, it could be that my engine dyno run was too fast (600RPM/sec) therefore did not load properly. Also it should be noted that the twin plug setup will improve torque over a single plug setup. Your engine has impressive torque downlow, which is what makes it so fast, as you often said.
Jean

Kevin

This is always going to be the life long debate with the 993TT and the 996TT. From my dyno runs I have always seen at least 450-500 RPMs difference before the K24's started to take off. The dyno sheet that should have been run on the same dyno was a K16 with the K24 compressor side ala GT1..

I agree with Jean that the new rolling road NON-inertia dyno's can actually load up the engine and provide very good results.. However, none of these results are good without baseline test runs. A sheet from one dyno and comparing it to the next dyno is just a piece of paper. The eddy current steady state dyno's that are being produced today have come along way.

But back to the numbers, we might as well test them all.. Stock, K24's GT1's Stage 2, Ruf's, K24/26's K24/27's and so forth.. I'm definately game..

MOD500

Your numbers are truly shocking TB

Bet its Millennium Falcon time at 4k revs.

I drove a K24 equipped modded 993 for the first time a few weeks ago, and I must admit the big hit when they really got puffing made my 16's seem positively asthmatic.

TB993tt

Kevin's post reminded me that I actually have the engine dyno run which RS did on my engine with the ZC K16 based stage 3s.
ZC K16 Stage3
2000rpm = 325NM
2500rpm = 360NM
2750rpm = 400NM
3000rpm = 465NM
3250rpm = 550NM
3500rpm = 605NM
3750rpm = 612NM
4000rpm = 620NM
4700rpm = 671NM that's nearly 500lb/ft
These are the engine dyno numbers for my engine with K24RS turbos on it, Kevin could tell exactly what their spec is, but I believe they are a K24 with a bigger (older type) K26 compressor ?
K24RS
2500rpm = 325NM
2750rpm = 375NM
3000rpm = 425NM
3250rpm = 480NM
3500rpm = 555NM
3750rpm = 675NM
4000rpm = 740NM
4550rpm = 757NM
Jean
I guess much of the validity or comparability (?) of engine dyno numbers is down to how the operator uses it. I know that RS (being Germanically thorough) work to a strict protocol so all their numbers are comparable and they are the same as Porsches' . I know for example that they have had various GT3 engines on their dyno and they are always very close to the Porsche quoted figure - despite what many of the dynojet shooters would believe

Jean

TB

I don't have the collection of Dyno charts that TB has, so I will just add the numbers that I have from my own setup. One of the sets of numbers was obtained through the engine dyno runs on which my engine was calibrated.
The other set of numbers was the one obtained from a MAHA dyno run that was performed at Manthey Motors in Germany recently. A few things that were different between the 2 runs were:
- The octane ratings, 103 Octane (engine dyno) vs. around 92 octane (mix of 91 and 93),
- The boost; 1.1 Bar on engione dyno vs. 1 Bar on chassis dyno
- The exhaust; one exhaust pipe welded (closed) during the chassis dyno run,
- Changed the mapping of the ECU to fit 91 octane fuel that I have here in the country. (I would say this is the biggest difference in performance)

The engine dyno shows clearly very low torque at the low end of the RPM scale, most likely because boost did not build properly, whereas the MAHA dyno run shows at higher RPMs lower torque most likely due to the state of tune, fuel, and slippage on the rollers.

In real life my car behaves very differently from what the dynos are showing, as lag is not very noticeable, quite less than my FVD K24 setup in any case, while slightly more than my ex-K16 stock 993TT.

I am picking up my car from the local port in 30 minutes (back home after 5-6 weeks!! ) so I will be able to experiment more on acceleration , boost, etc.. in the coming couple of months, and can do some tests if there is interest.

I summarized the numbers that TB posted in this chart and added mine. I also added a couple of guesstimates on TBs numbers just to fill the curve.

TB993tt

Great work Jean, always easier to compare when in graph format

TB993tt

There are some numbers for PSI's 538PS motor here page 9:
http://www.psi-motorsport.com/porsch...twagen-042.pdf
They appear to be:
3000rpm = 360NM
3250rpm = 420NM
3500rpm = 453NM
3750rpm = 495NM
4000rpm = 620NM
4250rpm = 680NM
4500rpm = 710NM
This motor appears to us K24s, maybe Jean could translate the text to see if there is any more accurate reference.
I presume these curves are from PSI's Maha dyno. I think one can only really compare the RS curves as comparable as they are done under identical conditions on the same machine. Whilst interesting these Maha numbers don't look comparable, I mean 360NM @ 3000rpm is 100NM worse than Porsche K24 450PS car. This does seem to point to what Jean is reporting, ie much more on road low down torque than the Maha shows.

TB993tt

One more. How about the 490PS Ruf turboR curves taken from their web site:
Ruf K16 hybrid:
2000rpm = 320NM
2500rpm = 395NM
3000rpm = 500NM
3500rpm = 570NM
3750rpm = 600NM
4000rpm = 614NM
Done on engine dyno - pretty impressive.

TB993tt

Hereare the numbers from a Superflow windyno @ 600rpm/second for a 729PS/843NM engine - It was for sale a while back on mobile.de and has a RS tuning intercooler - I guess it is K26 or maybe K27 ??
2600rpm = 317NM
3000rpm = 326NM
3200rpm = 337NM
3500rpm = 366NM
3800rpm = 405NM
yawn.......
4000rpm = 457NM
4500rpm = 648NM
5000rpm = 832NM
That's 375NM in 1000rpm - that'll be nice to controll

Woodster

TB,
thanks for the great info and I understand it is not just the turbos,
but a system built to work together. I used to put together my own small block chevys and know that changing a camshaft to a higher lift higher duration often provided more horsepower up high but you would lose that low
end pull that we all want on the street...
k24/k26 with good programming, I believe this is the key and good exhaust
(which I already have), an improved intake , will provide some very
impressive #'s (on a properly tuned 996tt motor), ala Cargraphic.
mk