roadsterdoc

With all due respect to Kevin (and I may be misinterpreting his post) 1.2bar with two different sized compressors will not have equal power. For example, a K16 pushed to 1.2bar will be inefficient (beyond its sweet spot) and will be blowing much hotter air than a K24 at 1.2bar. The hotter the compressed air, the less the volume (and thus flow) so there is less power. The K24 compressor is still pretty efficient at 1.2bar so it creates less heat, denser air, more flow so more power than the K16.
So if the 18G is more efficient at 1.2bar than the K24 it will produce more power at 1.2 bar (with proper tuning). If the 18G at 1.2bar flows more at lower temps than the K24, then the timing can be advanced safely for more power. I know Kevin knows all of this given what he has done with the K15/24 hybrids so what gives? I must be missing something.

Kevin

My response was to the fact that I know the efficiencys of both compressor wheels at 1.2bar. We are splitting hairs at 1.2bars.. That's my point.. It isn't until you start to raise the boost levels over 1.2bar that tilts the tables to the 18G.. You also have to remember that the wheel MASS of the 18G is 45% greater than the K24 wheel. That also impacts the performance.

roadsterdoc

OK, well that is where the mystery lies. The compressor maps for the KKK compressors aren't available to us common folks (that I know of). I don't know why not. Garrett is great about showing all of their maps but I have noticed that they often leave the x and y axes without labels. Most people don't have any idea how to read them anyway.

Bottom line is that there is and maybe always will be inadequate scientific data for the customer to use for decision making, but it probably wouldn't matter because most people do not know initially what they really want. The solution is to try one of everything and then decide.

tkerrmd

Ah, the tuners will love that way of shopping!!

roadsterdoc

Hey, if we don't keep them in business then there won't be any progress.

tkerrmd

You are correct and I also agree with your posts about how you feel about the hybrid turbo.
Ok we are both stupid doctors? But we had a physics course or two and the stock turbo vs hybrid turbo flowing the same air and hp at the same boost still is confusing to me!!!

Kevin

Tom bolting on a set of K24's with a larger compressor wheel will not give you more HP and torque without addressing other issues.. Heck, with a EP exhaust a GT2 (same engine as yours) just posted high 10's in the 1/4 mile. The Porsche ECU tuned correctly for 1.2 bars (with stock K24) will perform closely to K24 with 18G compressor wheel when, one has "stock" fitted components.. As I said earlier, stock fueling, stock intake system, intake plenum and so forth. If a person spends the money to reduce the intake restrictions (this does not include a airbox/filter) and internal back pressure, the larger compressor wheel will move into a considerable "favorable" section of the compressor map. The static pressure is reduced and more CFM is available to be pumped into the engine.

roadsterdoc

Well, we don't have any secondary gain.

tkerrmd

Kevin, what would you say the next most important upgrades would be?
turbos, ECU, and straight pipes then ? rest of intake system and upgrade fuel system. pump and FPR or injectors and fuel rails.

thanks may need to call ya!!

John D II

Tom,

If I were doing the K24/18G's with 5 bar FPR, but without the injectors, pumps and intake - in other words, staying around 600HP...I would install a better air intake (I had good luck with and liked the V-Flow), intake pipes to the turbos (FVD or EVO), as this is a great time to do them with your motor out of the car and the stock pipes are pretty restrictive, Blown 6 or Evo IC's and finally port the headers. This is all pretty mild stuff, but it will enable the turbos to breath/flow better and the car will run stronger. It will also spool a little quicker than otherwise. If you wanted to do one more thing, you could consider the RSS plenum after the TB.

Tuned

So you are saying that untill you raise the boost that you are going to make a minimal power difference?

I think that the efficiency for the two may be different but I think that PEAK efficiency is different yes. But over all efficiency of the motor itself increases as you are able to increase airflow with the larger turbo's thus helping to create a better Volumetric Efficiency.

At 1.2 bar with the K24's vs. Hybrid Turbos there is going to be a power difference. I don't think it would be minimal either. It should be susbstantial. And if you increase boost and get the turbo into it's PEAK efficiency you are going to make more yes, but I don't think that the turbo gains would be minimal at 1.2 bar.

Just my take on the whole thing.

Kevin

New to Rennlist, Congrats...

First post and you work where?? Who??

Until you free up the intake and add fueling for the 18G, the gains are minimal for a stock engine.. How many tuners are saying that there (K24) kits are 600HP kits.. And the basic K24/18G kit is also rated at 600HP?

Tuned

Thanks good to be on here.



I have to work at a shop to have knowledge on turbo's? I am just an educated consumer I guess. I have been working with turbocharged cars for 10+ years so at least I believe I know what I am talking about.

Also HP claims with tuners saying that there setup produces "X" amount of horsepower is all just marketing. I would rather see dyno sheets of exact setups back to back in a controlled enviornment rather than 2 different dyno's as in my mind there is no comparing two different dyno's. I would rather have no data than incorrect data.

Overall principle is the same for turbo's in internal combustion engines in relation to gas dynamics is all.

Just a thought and by no means am I trying to argue.

roadsterdoc

This just keeps getting better and better.

KPG

Was that the car in the video at an airfield in Brooklyn?