TB993tt

Guys, don't forget it is no gear changes and thanks to VTG on full torque curve throughout the range of the run - the 4th gear is pretty optimal for this increment, having said that it does feel scarily powerful in this cold weather...

TB993tt

Talking ultimate VTG motors, I read this hype from Champion on the hype site;

We also have a 68mm turbo that will take you up to around 675 at the wheels (~840 crank) on a stock motor, and about 800 or so at the wheels (~1000 crank) on a built motor. Beyond that you'll need to explore non-VTG based options out there

So they are claiming 1000 crank hp with VTGs which is way more than my 730hp.
I have demonstrated how in DIN 20 degC conditions my IATs go over 60 degC and the hp is pulled back by the ECU by reducing the boost and hp to around 700, this is using my very expensive intercoolers, massive VTGs and all the tricks my race engine builder knows.....

I want to know WTF is going on, is it simply inflated numbers to play on the same playing field as all the others or do Champion have some way of keeping the IAT lower so they can make more power ?
Is Champion's power produced at lower loadings ie under 130mph ?

Has anyone ever seen any Durametric data on a Champion VTG engine at high speed and loading, I would so love to see that, it may show me which direction I should be heading, their 840hp engine must be using 2100+kg/hr at the MAF at full load - is there any data out there other than hype,talk and low speed acceleration for one of these VTG cars ?

Nick Wong

It isn't hype even though that forum (as does this one to a lesser extent) is full of shops that do hype up stock block max power output. There are two Champion 3.8l 68mm VTG GT2 cars in the USA right now that I know of. The yellow one is virtually undrivable according to people I know, and mine (the grey one) has the different maps in order to make it drivable (my request to Champion that they improved upon further by spec'ing 2 ECU units to swap). On the race gas ECU maps the MAFs are disconnected because they're max'ed out (and this is with big tube MAFs) quite early, and that is in 80+F temps at high humidity (south Florida temps in October). I don't think the highest output file is useful for anything other than scaring the pants off myself- the gem of a file is the track file, 750whp/650+ ft/lbs torque, with torque flat from 3500-6800, 7500 redline. I was told that file should use 100 octane (low grade race fuel such as Sunoco 100 unleaded) because at the high boost point the ignition retard is present by a degree or two on 93 octane street fuel. On the MAFless ECU I was told to use a minimum of 104 octane (VP C12 cut with 93 octane street fuel would suffice). No ignition retard recorded under testing when they follow that protocol.

The only difference in the engine build between mine and the yellow one is that I have 997TT intake manifolds and the other car has the Champion prototype carbon ones, worth about 20hp at the top (not enough to justify the cost IMO). That car also has a fancy fuel system but we use the same injectors and hence same injector map profiles. I haven't done any testing because Chicago is awful in the winter, with the salt on the roads and all.

If you want to know more you can PM me. I'm happy to discuss this with you but I don't need the crap that accompanies a public forum posting. Although its easy to put detractors and trolls on my ignore list, it's even easier to just keep info to myself.

TB993tt

Nick, thanks for the post. I don't really want to PM you, I want to have this discussion in public. Over the years public discussion particularly on RL has educated many of us. The 60-130 measurement for eg was started on the 993tt forum here and we started it to verify the silly dyno hp claims being made back then..... there has been some good progress on intercoolers also I think so now we can buy a set of factory $1000 units which appear to be better than all the "tuners" wares - bad for tuners who don't actually test the coolers and show real data (just make videos about them )

So you have been told you have 750whpand 650 ftlb of torque so flywheel is what ? 850hp (or is it 915hp using the loss they say it their splurge above) and 750ftlb or 1020NM
You must be able to see why I am about the numbers,( I have 734PS and 920NM and at very high speed in 20c ambient I have nearer 700PS !).... is it simply chassis dyno number inflation - maybe the whp is actually equivalent to engine dyno crank hp ?

Have any of these motors been run at high loads/speeds ? are they tuned to deliver at sub 130mph speeds ?
I can see how one could turn up the wick if the speed is kept below 130mph since the IATs can increased to 45-50c at 130mph using more boost than I have hence more power....
Will a set of Durametric data ever be available for a 190mph full load run ? is this irrelevant to the tuner/owners, but what about on the track surely the heat will prevail ?

Is it the race gas which is making the power, we only run on 99RON which I understand is about 93/4MON so I guess the 100MON stuff must allow a much more aggressive timing tune..... but what about those IATs ? Are the Champion VTGs magic. do they not run hot like other VTGs ?

need to see data to understand

pete95zhn

There might be a (part) of the explanation. Porsche engineers developed expansion intake for GT2 for a reason or another...not "just because it's cool".<--No pun intended...maybe...
If I've understood corrcetly the idea of expansion tank the inlet airflow is kept in a same relative volume & pressure until the combustion chamber where it expands and thus cools. P=V*T from physics and so on... This eliminates the increased temperature of higher boost pressure required for GT2's increased power. Apparently GT2's VTGs work in their not-so-optimum area of compressor chart -which is not available.

If Champion has compressor wheel that works in it's optimum efficiency range, like 75%, it has a huge advantage (in temperature) over a wheel that has to compress air at -let's say something like- 66% efficiency. If there's a also a difference in Pressure Ratio too, this temperature advantage rises more. (See below) It's really pity that we do not have OEM VGT, neither turbo's nor GT2's, compressor maps available for comparison. But for example Borg Warner has EFR tuner turbo model range, where EFR6758's compressor (53.9mm inducer/67mm exducer = 65 trim) flows 0.27kg/sec - 1.3 bar @ 75% eff or .34 kg/sec -1.3 bar @ 65% eff or .32 kg/sec - 2.0 bar@ 74% eff and maxes out at .36 kg/sec -1.8 bar @ 70% eff. These kind of flows flow mean about 340 / 425 / 400 / 450 hp. From one turbo.

BUT there's a one big question left. How much does the turbine flow, and what's the backpressure? At some point the turbine is also maxed out and increasing compressor flow/charge pressure just increases backpressure. There's a kind-of-a rule of thumb that when backpressure divided with charge pressure stays between 1.0 and 1.5 there's no problem. Over 1.5 starts to build up heat and over 2.0 the engine goes kaboom.
Under 1.0 is the place where the real power lays....like in past turbochaged F1 engines. Over here is a Fiat 1/9 that has 600 hp (out of 2.0l engine) and pulls to over 300 km/h on a mile. It drives to and from the airfield, no need for trailer. Pex/Pin is less than 1.0...
Someone should really datalog the backpressure, ie pressure in exhaust manifold and make a table of Pex/Pin to see what happens in a standard and tuned VGT.

avader906

difficult to compare power numbers across different chassis dynos (or same dynos with different setups/operators) - you can introduce so many corrections that the absolute number does not make any sense.

the easiest (practical) way to get the relative comparaison of power numbers (out here on the forum) are 4th gear full throttle runs with durametric trace (to get VE curves > extrapolate HP/tq) short of running both engines on an engine dyno/stand. it is useless to compare numbers from different fuels and fuel specific tuning - same mechanical setup is optimized differently under different grades of fuel.

re gt2 expansion type intake manifold - expansion (and pressure drop) occurs before the combustion chamber. there is tradeoff between flow (pressure drop) vs temp that P found optimal for that specific flow bracket (VE) - most likely due to heat soak of the entire intake tract (hence why it was first made it on GT2 platform). you can extract much more from VTG design - this requires R&D on turbine housing and lubrification - none of "street" tuning programmes have that done.

PS: an engine optimized for torque will show more heat soak with powerband from lower revs. Same mechanical setup could be (in theory) optimized for higher rev power band - less heat (&less torque) but more HP say at 6.8k revs.

Nick Wong

Pete-
Champion also uses a billet compressor housing for their 65mm and 68mm units, much larger than the OEM 997.2 Turbo, contrary to some other misinformed opinion. This housing and trim was optimized by Champion and Tial and is only available from Champion, so trying to figure out efficiency based on what we know of the OEM housings is moot unfortunately. The 68mm trim maximizes the efficiency of said billet housing. They have a long term project for the next level up which may or may not work- as we all know theory and real world use are two different things many times.

Also, Champion's intercoolers are quite good. No hype, stock thickness, well designed end tanks, OEM fitment. The cores are NOT Bell which, I think, erroneously or not, are junk (most aftermarket ICs in the US use Bell except for two or three which is why most of them suck). The new GMG ICs are pretty good copies of the Champion ones if you ask me.

TB-

I'm sure running the higher octane is for knock/preignition/detonation resistance, to minimize the ignition retard. At those HP levels, using 100+ octane fuel is the norm here in the US.

And here's a hint of advice concerning power output and dyno charts- if it can measure output at the wheels it can measure parasitic drag too- and it's nothing like the BS conventional 15-20% most idiots who browse forums assume it is (and even less with a high efficiency design like the GT2/3/C2 rear wheel, rear engined cars). The only reason Champion is forced to use "conventional" crank numbers is because that's what all the other companies use- hence their caveat by always quoting whp numbers from their Dynojet so that you can form your own informed (or uninformed depending on your understanding) opinion.

pete95zhn

Yes, I'm well aware of those Tial housings and brought up BW EFR compressors (also billets) as comparison of possible power range of (almost) equal size. CMS's 68mm (exducer) wheel has 49.05mm inducer, which brings the comp wheel trim to 52.
A quote from Garrett's turbo tech: "The trim of a wheel, whether compressor or turbine, affects performance by shifting the airflow capacity. All other factors held constant, a higher trim wheel will flow more than a smaller trim wheel.

However, it is important to note that very often all other factors are not held constant. So just because a wheel is a larger trim does not necessarily mean that it will flow more." = Apples to oranges in this case, mostly.

Yet -IMO- the turbine starts to be the key factor in these amounts of flow...without published data no-one really knows when it starts to be the restriction.

Nick Wong

Pete and Toby-

Do you guys have any data related to the back pressure in the exhaust manifolds under high boost conditions with the OEM exhaust housings?

GT2Driver

Hi Avader906,
I tried to mail you but have no answer so far. Pls respond to my email address.
Rgds

TB993tt

No idea I'm afraid.

From another thread but very illustrative of why we need to see data for tuned VTG engines, with 8 second dyno runs in Florida/Arizona heat the blower fans are able to control the IATs and keep them down but try it on a Maha with loading for 30 seconds in 30DegC ambient and the real picture emerges, IATs at 100degC at 6500rpm and max power 60hp down !
Data traces of what is happening on the road at maximum loading in 6th gear is the true evaluation of a "tune"

Nick Wong

Toby- that's all fine and good from a theoretical POV, but from a practical POV that's a bit useless for me since I would never drive my car in 6th at WOT for 30 seconds at a time except for perhaps Michigan International Speedway or Daytona, in which case the intercoolers would see 160+mph of air. Which brings me back to my last post- what psi back pressure do you see in the manifolds before the exhaust housing? I know what we see, just curious what you guys see.

pete95zhn

Sorry, but no. Yet it's easy to measure, just remove other of the EGT probes and screw in a plug with about 20 cm of hard pipe. Connect this pipe to a pressure gauge ( dial or electronic ) with a flexible tube and do some test drives. Get a friend to do the logging. If you don't have a electronic device to collect both boost and back pressure, use a video camera to get synchronized data...

I might do this when I get my car in an one piece.

Europipe's Stef has done some exhaust back pressure logging, but he's measurements are done after the turbo to see how big restrictors exhaust & cats are. IIRC those results can be found from Europipe's web pages.

TB993tt

But what is "theoretical" ? I am simply trying to understand how Champion (and others) are quoting much higher power and torque numbers than the ones which I have when my engine is limited at around 700hp DIN by IATs.

The word "theoretical" doesn't really apply in terms of what I am trying to establish ie manufacturer (specifically Porsche) DIN measured hp and torque because only when we have that can we really compare numbers and make informed observations/discussion.

You stating the above that's a bit useless for me since I would never drive my car in 6th at WOT for 30 seconds at a time points to what I queried earlier ie that these Champion tunes are specific to an acceleration/loading range which is probably up to 130 or so mph. If this is the case which it sounds like it may be then I can begin to understand how these big numbers are achieved.

There is a great web site in the link below for a Swedish company who sell dynos and they have an obsession with manufacturer horsepower. If you read through the whole site it becomes quite clear how big power numbers can be achieved with lower loading and yes they are real numbers but they are not comparable with manufacturer numbers....

http://www.rri.se/index.php?DN=48

TTurbine

Nice find Toby

Reminded me back in 2008 when i did a test run from 20-300 kmh in my RUF 550hp 997 TT ( Engine dyno Ecu + Reworked stock exhaust + filter ) with my freinds Evoms 620hp tt with all there shiny accesories and there large intercoolers.. the evoms car got the jump before and 200kmh my car had left him about 2 car lengths with the gap increasing till 300kmh..

Where did the extra 70hp in the evoms car go?