yes well, 9FF has had more than its fair share (to be VERY diplomatic) of not so nice (again VERY diplomatic) nasty customer experience reports. I personally know of quite few of them and had 1 myself.
My understanding is that the ES guys know what they are doing and have a good reputation. Given that it only takes 1 bad "mistake" to ruin a tuning package, I think that 9FF may not be on the top of the list of tuners to do a JV.

 

I'm afraid the "ultimate VTG engine" is over.....

My engine has been extensively tested on the engine dyno wearing its new ported big valve heads and cams and big GT3 intake manifold.

Even with bigger compressor VTGs installed the maximum hp recorded was 758 and there was knocking present.
Using E10 fuel the knocking could be reduced.

They rigged up a pressure sensor on the exhaust manifold and measured 3.2bar.

What I think this means is that the biggest available VTG exhaust side (ie the GT2 one) cannot flow more than this and creates this back pressure which creates the heat and the knocking.....

They are working on being able to install K24 based turbo and retaining all factory 997GT2 electronics, importantly the TC/PSM.

They have an Alzen 996GT2 race engine in which is baiscally the same spec as mine but runs K24 based turbos at around 1.2bar and 996 electronics and makes over 800PS with all the numbers in the green (green enough for a competitive race car)........

 

Porbably high IATs are over too since your going in this direction..

Toby have you considered GTX or GT3076 Turbos instead of K24s ?

Karol is running GT30's Turbos , Rods, Cams, Injectors and pushing 830 PS on Maha.

Your built engine might push close to 1000PS Din with those Turbos

*Edit*

His car also had TC/PSM Problems but Ansgar resolved them..

 

You've been very close to Ka-Boom... Backpressure measurement should be standard procedure when really tuning turbos. Backpressure/boost pressure ratio reveals kompressor vs turbine mismatch (or max usable boost pressure with given combination) and possible exhaust restrictions too. I surely would like to see other tuners'/engines' numbers too.

PS. See my posts #155 & #192...

 

Mo
I believe Karol didn't ever get the factory TC systems working satisfactorily.

I have thought about the Garrett stuff but these guys only work with KKK - If they have their own K24 based unit which reliably flows to over 800PS and spools early then there probably isn't any benefit to the Garretts other than price and that usually reflects in the quality/longevity ?

I'm still not sure which direction to go in, I've not seen the price or the timescale for the latest proposals..... I'm tempted to dial it back to the 650PS range on VTGs

Pete
Yes I just re-read your posts, you made this call already didn't you.

I don't think the 997 electronics will allow kaboom, the timing and boost are fully controlled and are constantly reading and reacting to IAT and VTG temps, I have some of the tables and the fun starts being reined in at 50C IAT on my motor.
This 3.2bar was measured under controlled conditions on the engine dyno with them steadily increasing boost, I think they were taking it to the limits to see where knock started...

There are many K16 based hybrid 996s running around with near 800hp and mega high IATs whose builders have no idea where this manifold back pressure number is at, you rarely get to hear when one goes pop.

 

Well, Garrett isn't hardly the word of god in turbochargers, although well advertized. IMO bolt-on is the issue here, without a need to modify headers or exhaust flanges. water cooling is nice to keep too.

Yes I did, but i just had to make this (rather childish) note here in the "I told you so, didn't I?" -style...

That was your luck & benefit. Otherwise you'd been struggling with bad acceleration numbers compared with the power you should have had (if lucky) or blown the engine when doing flat out at Bruntingthorpe (if not so lucky). Unfortunately some tuners disable (so I have heard) some safeguards in order to get their numbers high.

Unfortunately true. And that's also the reason why I'd like to see Champion's backpressure numbers with their 68 mm VTGs.

 

750hp+ with VTGs with short gear ratios and a light GT2 is pretty enough me thinks Toby..
When i tried GT2 with K24 hybrid with 750-800hp I did not like the power delivery tbh.
My vote is to keep those big VTGs with the new upgrades @750+ hp. The spooling you had in your last package was the best I have seen and with another 20hp, flatter torque curve etc I am sure you would be happy. The K24s will spool 1000-1500 rpm higher and I fear you may not like it.

 

Now I got it. They're living on the edge too..:

On stock engines, we typically max out at 23psi with both the 65's and 68's.

On some of the 3.8L and other built engine cars we've built, we normally run about 28psi. We've run 30psi on one car...but eventually backed it down to 28, as that seemed to be the sweetspot. These are all with our 68mm VTG's.

Backpressure, is a good question...I'd have to check with the guys in the shop to see if they've done that.

Later a clarification:

We have measured back-pressure on the turbochargers only a couple of times...but each time was at higher boost on cars with built engines.

However, the info is still pretty valid. At 30psi boost, we measured 60psi back-pressure in the manifolds. At 25psi boost, we measured about 48psi back-pressure in the manifolds. We only did these measurements a few times for a few particular cars as we were testing to see what type of turbine wheel modifications were necessary to get max power.

Interesting though that there's a clear decreasing tendency but it's effect on final result is unknown without seeing EGT/IAT numbers and compressor maps. But no-one has yet reported exploded engines. Personally I wouldn't like to run Pex/Pin ratio like that on my car, but it's a trackday toy meant to be driven flatout =) extended periods of time. For occasional highway fun that's OK.

 

No they're not Pete, they have magic VTGs whose physics operates in a parallel dimension where 2:1 ratio is ideal

Oh and ask 'em at what loading they measured their 900C VTG temps, they never get to run them fast by their own admission, I bet at 6000rpm in 6th the numbers are a bit different !

 

Pete
I totally got it wrong (blaming language barrier) about the VTG units being used in the Mission 400 car or being used with vanes 'open'..... they have been using K24 based items.

Here is a pic for enthusiasts and I believe a first on the forums ? a poster's twin turbo engine on an engine dyno getting some proper tuning, problem is doing things this accurately tends to reveal many problems which your 8 second chassis dyno 4th gear runs will not

 

I know this it not appel to appels

But here is some fact from my race car

997 tt engien
1000cc injectors
software
bmc airfilter
oem 997 gt2 turbos
striaght 3,5 inch pipes with cats
e85 fuel

Performance 100-200km/h @ 4,2son racelogic performancebox

Time for uppgraded 65mm vtg this summer

 

Rickard,

Whats the weight of your car ?

 

Toby, thanks for clarification. BTW, here's Champion's answer to my note about Pex/Pin ratios from that another thread:

Me: Rather high Pex/Pin ratio, clearly shows the retrictive nature of VTGs' hotside. GIAC has done good job in programming to keep engines alive, there's not much room for errors...must be a lot of heat there...

Champion: Well actually, a 2:1 ratio of boost to back-pressure is ideal, so at 30psi boost these turbos are working in perfect efficiency. At full boost and at max RPM we normally see EGT's around 900º, which is perfect for a VTG. Remember, they're built for us by Tial, who are more or less the industry leaders in turbocharger technology.

Me: Under 1.0 is the place where the real power lays....like in past turbochaged F1 engines...etc...

Champion: Well you're definitely also correct to a certain extent, but I think the comparison you're making doesn't really apply here. Even completely stock, the 997TT has a a very high pressure ratio. If we lowered the ratio on our setups, we would definitely sacrifice a lot of low end torque. We're also running on the factory Porsche engine management and VTG. The smaller 4 cylinder engines you mention are most certainly built for a specific purpose...drag racing. They probably have large turbines, stand-alone engine management, and anti-lag or some other enhancement to low end power. The turbochargers most certainly also require frequent rebuilding.

When we initially tuned our turbos, Tial even mentioned that we had some more room to go higher on ours...even as high as 65psi back-pressure...but we found it wasn't necessary.

The cars we build have to be ready to run flawlessly day after day in the hands of our customers, with excellent driving qualities and still deliver the power. Tons of street driving, 100's of track hours, and perfect reliability. I think we've found the best of both worlds to be honest.

Now that we're in this backpressure issue (Which I seem to excessively like... ) I'll add here some speculation and facts from another forum.

As for the escalating exhaust backpressure with engine speed, it is indicative of one or more of the following issues:
1. compressor power requirement is escalating sharply
2. turbine is running out of flow capacity
3. turbine efficiency is plummeting
4. turbine backpressure (downstream of turbine) is escalating

#1 above is due to one of both of the following:
a. compressor pressure ratio is going up (this can happen even if boost remains constant, or even drops)
b. compressor efficiency is plummeting (running deep in choke)

In a. above, there might be a big pressure drop in the intercooler and/or plumbing. And/or a lot of inlet depression (upstream of the compressor inlet) due to a restrictive filter and/or undersized plumbing.
In b., there could be a leak in the intercooler plumbing, compressor could be undersized, or just plain crappy.

Back up to #2, this is obviously affected by any leaks upstream of the turbine (including a wastegate!).

Quantifying/assessing plumbing-related pressures/drops is aided with proper instrumentation. You can use separate gauges (one at the compressor discharge, and one right upstream of the throttle body) and subtract the readings but there's a lot of measurement uncertainty this way. A better way is to use a delta p gauge. Same goes for more accurately measuring engine delta p. For compressor inlet depression measurement you want an inches of water gauge. Using a boost/vac gauge here is like using a claw hammer to remove a splinter.
Once all the plumbing/housekeeping-type issues are identified and addressed you can more accurately determine whether backpressure issues are hardware (turbo)-related. If so, it helps a lot to have representative compressor/turbine maps, which is not as common as you might think.

And one more thing about high EGTs:
xxxx's high EGT problem was largely due to an improper tune, specifically, using too much ignition timing retard to accomodate a boost level that was too high for the fuel octane.

 

1190kg empty

 

Pete
I am not really following who said what there ?

The bottom line for me with the Champion stuff is that sure their VTG engines are working fine for the use they are getting and that use is all below about 150mph so never really out of 4th gear.
Remember the IAT testing I did, it really heats up in 5th and 6th - IAT is totally indicative of EGT and this backpressure.



So yes the Champion stuff is great for sub 5th gear work and indeed probably does have the 800hp or whatever they claim but this isn't really what we are talking about on this thread, I am interested in Porsche hp which is there at maximum speed.

Rickard's is possibly similar, 4.2s 100-200 is mighty fast but I'm not sure what effect that 1190kg has on the acceleration ?
What sort of power numbers are you getting from those stock GT2 blowers ?