Skunk Workz

I have dealt with such guys before..I do understand you. Hopefully you can understand that I don't want my competition to do the same as I do...at least not yet.

I know that too...that is why I said I would not get it much over 100% VE. On other engines that's easier to tune,it's a different story..

And yet again,I do say that I will roll up my sleeves and give you proof,I just can't do it yet,as I have yet to dyno a 2.5 with these mods. Before and after comparisons would do it for you,wouldn't it?

Konstantin

hello
a question for the experts:
Why do you have at 1.3 bar boost 20lbs/min and at 1.8 bar also 20 lbs/min
BUT you know the car makes at 1.8 bar (o,8 bar) more power than at 1.3 (0,3 bar pressure)
if you have at both boost levels same flow you should also have the same power ? ;-)

Konstantin

Chris White

Skunk - Yep, I look forward to taking a look at your results – I do welcome any new developments / tweaks to the 944 series, I guess I am just to jaded by past miracles, who knows? – you just might have something – are you aiming these mods at the NA or Turbo engine?

Konstantin – I don’t fully follow your question. ?

Chris White - I am generally skeptical about everything!

Konstantin

Hello
ok I try again
take a look at this graph

you have the same flow of 0,1 m³/s at 1.1 and at 1.9 bar boost
Same flow at two different boost levels.
Why do you have more power at 1.9 bar? since you have the same air flow?
Do you have the same air flow?

Konstantin

Skunk Workz

That mod works on both,only thing you have to do the turbo'ed engine slightly differently due to the higher pressure in the plenum/runner.

Bill

Chris,

In defence to Skunk....

I paid good money for headwork from Lindsey Racing, with work being done to increase the velocity in the exhaust port. They would not tell me what was being done. When I questioned work being done to the ceramic port, all they would say is....the improvement was worth the cost. Go to Lindsey website and all you will find is your "snake oil" description. I am pleased with the headwork though.

schnellfahrer

Bjørn; and you thought I was giving you a hard time?

Skunk Workz

Eivind;nope,I was expecting this...nice thing you "gave me practice" on PCN's forum..

Russ Murphy

>>>you have the same flow of 0,1 m©¯/s at 1.1 and at 1.9 bar boost
Same flow at two different boost levels.
Why do you have more power at 1.9 bar? since you have the same air flow?
Do you have the same air flow?

Konstantin<<<

The answer is you don't have the same flow at two different boost levels. To acheive this would require two different motors (different VE, displacment, turbo, etc.).

Skunk Workz

At 1.9 you pack more molecules of air in that 625cc cylinder that you'd do at 1.1 due to it's higher density...all other factors the same. The air flow is the same (volume-wise..you still fill 625+cc's) but it packs more oxygen for a given volume. Then you can burn more gas,and have more power.

Chris White

Hmmm….I am guessing that a few bits of info need to be put out there so that the compressor Isopleth can be understood.

First – how to use a compressor isopleth
Determine the flow capacity at a specific boost level for the engine in question – The example the Konstantin uses 1.9 bar absolute (.9 bar of boost). Then you can figure out the mass of air* that the engine will consume at different RPMs and plot this against the x and y axis. By plotting this out you will see how the performance of this compressor matches up with the intended application. In this case the compressor hits the following contours on the Isopleth –
3000 rpm – a little over 65%
4000 rpm – 70%
5000 rpm - a little over 72%
6200 rpm – 72%
This is a fairly nicely matched application.

To address Konstantin’s question a little more directly –
If we assume the same air flow (0.1m3/s) with one engine at 1.9 bar and the other at 1.1 (assuming they both have the same VE and rpm) the 1.1 bar engine would have to have 72% greater displacement. (if total air low is the same then larger less boost = smaller higher boost).

Just for giggles – the 1.9 bar engine used as an example in the isopleth would run the compressor at 70% efficiency @ a tad less than 4000 rpm. The 1.1 bar engine would be running the compressor at 50% efficiency (pretty crappy). In the end the 1.9 bar engine would be putting out more power at 4000 rpm due to its more efficient use of the turbo compressor.

It might make a little more intuitive sense if you look at the scale choice on the axis – cubic meters (this is assuming uncompressed gas) or kilograms – we are talking about the mass of the air not just the physical volume


* the mass (or uncompressed volume) of air used is based on the mechanical displacement of the engine x RPM x Volumetric Efficiency

Chris White

Laust Pedersen

Skunk Workz, Referring to you comments to my post, I can see that you have a better understanding of reality than the thrust of my post. We are essentially saying the same thing. The continuous flow I was referring to was for the turbocharger itself not a turbocharged engine.

Skunk Workz

I noticed. In reality,a flowbench can give you the picture of necessary flow from the turbo to the plenum. From there on,it can tell you something,but not all.

Russ Murphy

>>>The air flow is the same (volume-wise..you still fill 625cc's)<<<

It's the same volume at the cylinder, but what's the volume at the the air filter?

Chris White

Its really mass but you can use uncompressed volume.

Chris White