Twin Turbo 928 fixed and back out there terrorizing the streets!
12-30-2013, 09:11 PM
#736
Integrating the exhaust manifolds and the turbine housings more would create the following problems. First, there would really only be a benefit if the combined part could be cast together. This however would lock one to only one kind of turbine housing and at these production volumes flexibility is the key. Second, as long as one is using Garrett center housings, there are limits to the angle at which the units can be installed. The angle restriction and the steering staff together pin the turbo location down pretty precisely. Third, installing these things is a big enough jigsaw puzzle as is, and it would only get worse with integrated components.
If John is going to change the kit in a meaningful way, I predict he'll start having some components cast, but still as separate components. But that's pure speculation - I didn't and don't make any of these components you see here, they are all John.
Overall, for anyone outside the ****-nanny states who's interested in 600+ rwhp with high reliability in street driving, what you've seen in this thread until the spring 2013 is _by far_ the most cost effective and convenient way to get your 928 there. What has been done since theb is just a little bit of envelope pushing, in the name of a science project. If you just want to go fast, as fast as you can go with street tires, just stop with what I had in spring 2013 and let the rubber burn.
If John is going to change the kit in a meaningful way, I predict he'll start having some components cast, but still as separate components. But that's pure speculation - I didn't and don't make any of these components you see here, they are all John.
Overall, for anyone outside the ****-nanny states who's interested in 600+ rwhp with high reliability in street driving, what you've seen in this thread until the spring 2013 is _by far_ the most cost effective and convenient way to get your 928 there. What has been done since theb is just a little bit of envelope pushing, in the name of a science project. If you just want to go fast, as fast as you can go with street tires, just stop with what I had in spring 2013 and let the rubber burn.
So you won't talk about your AMG purchase? Shame.
Weistec has downpipes and a tune to get you to 700tq.
12-30-2013, 09:43 PM
#737
Nordschleife Master
Thread Starter
With the gt3071r's and pump gas, changing the intake manifold to the best possible intake manifold in the world would not make much difference. I've done the compressor hp computations and also the intercooler effectiveness and intake runner gas expansion calculations. Given that the compressor mass air flow is a constant, the intake manifold would do basically nothing.
I also don't understand why the stock computer is a handicap for the peak power. Is it because of fuel? That wouldn't make that much sense, because at peak power rpms the duty cycle is long and at these densities the cylinder to cylinder lambdas are going to be close enough for government work. The ignition system has a knock sensor logic, so with pump gas it's all I need. One big reason for _not_ switch the ECU is the cost - throwing $5k for basically no benefit with gt 3071rs.
Both intake manifold and ecu considerations may change with these bigger turbos. In fact, we do know that when the manifold air density gets to a higher level, distribution problems do appear. The friction impact grows, too. It's possible (I would even say likely) that with these bigger turbos we get to the point where there's a real benefit from a new intake system and an aftermarket ECU.
I also don't understand why the stock computer is a handicap for the peak power. Is it because of fuel? That wouldn't make that much sense, because at peak power rpms the duty cycle is long and at these densities the cylinder to cylinder lambdas are going to be close enough for government work. The ignition system has a knock sensor logic, so with pump gas it's all I need. One big reason for _not_ switch the ECU is the cost - throwing $5k for basically no benefit with gt 3071rs.
Both intake manifold and ecu considerations may change with these bigger turbos. In fact, we do know that when the manifold air density gets to a higher level, distribution problems do appear. The friction impact grows, too. It's possible (I would even say likely) that with these bigger turbos we get to the point where there's a real benefit from a new intake system and an aftermarket ECU.
Last edited by ptuomov; 01-03-2014 at 06:36 PM.
01-03-2014, 06:42 PM
#738
Nordschleife Master
Thread Starter
Turbo speed sensor install
Both compressor housings will be wired with a speed sensor. Turbo speed sensor is the type of sensor that 95% projects would see no benefit from. It's only useful in two situations: First, when doing development and testing for a system, trying to match the components while also trying to figure out what exactly is going on in the system. Second, with very advanced ECUs which can have turbo management algorithms. Our case is the first one.
Here are a couple of photos of how the sensors will be installed. The angle and depth are important, so it's a bit of an operation:
Here are a couple of photos of how the sensors will be installed. The angle and depth are important, so it's a bit of an operation:
01-10-2014, 05:37 PM
#739
Nordschleife Master
Thread Starter
Turbos are done!
The turbocharger units are done!
One of them had to go under the knife one more time to get the mid section and the inlet pipe to fit:
One of them had to go under the knife one more time to get the mid section and the inlet pipe to fit:
01-30-2014, 07:28 AM
#740
Nordschleife Master
Thread Starter
Test cams
I got a big box of intake cams today for various planned turbo tests down the road. There's a baby girl cam with 225 degrees @ 0.05" and a girl scout cam with 235 degrees @ 0.05". What makes these cams special is the adjustable center sprocket that one of the RL participants fabricated for me. These adjustable center sprockets allow for experiments that change the LSA and thus the overlap without having to swap cams. Because turbo motors can react unexpectedly to overlap, these cams will allow us to dial the exactly right amount of overlap for this turbo system on a dyno.
02-03-2014, 09:08 PM
#742
Nordschleife Master
Thread Starter
Lines for turbo oiling and cooling
Turbos must be oiled and cooled. These are ball bearing turbos, which naturally means that the center housing is "water" cooled with the engine coolant. Coolant lines must go in and out. In addition, we have oil feed lines and a balance line between the oil sumps. The sumps are scavenged with a single pump, and the replacement fluid is drawn from the crankcase air-oil separator, which conveniently actively scavenges the crankcase air-oil separator.
It goes without saying, all this requires a number of lines. John run them in a really clean way, as the below photos show. The coolant lines are rubber and oil lines are teflon. Since the heat can be extreme at spots, metal braiding serves a functional purpose in distributing the hear, acting as a radiator of a sorts. Stainless steel braids have to be secured well, otherwise they'll grind thru almost anything as the engine vibrates.
It goes without saying, all this requires a number of lines. John run them in a really clean way, as the below photos show. The coolant lines are rubber and oil lines are teflon. Since the heat can be extreme at spots, metal braiding serves a functional purpose in distributing the hear, acting as a radiator of a sorts. Stainless steel braids have to be secured well, otherwise they'll grind thru almost anything as the engine vibrates.
02-03-2014, 09:38 PM
#743
Archive Gatekeeper
Rennlist Member
Rennlist Member
I have developed a real appreciation for the importance of properly securing hoses and lines, that routing looks great.
Three questions:
1. Do you still use a CPS? If so you might want to install it first...
2. How is your fuel return line routed to the fuel cooler? (I think it'll end up way above those coolant lines, just asking)
3 Likewise, does any of that conflict with the heater return hose to the Y-pipe? You may find that you will no longer need a heater core in this car, and you can just enjoy the radiant floor heating you've installed......
Three questions:
1. Do you still use a CPS? If so you might want to install it first...
2. How is your fuel return line routed to the fuel cooler? (I think it'll end up way above those coolant lines, just asking)
3 Likewise, does any of that conflict with the heater return hose to the Y-pipe? You may find that you will no longer need a heater core in this car, and you can just enjoy the radiant floor heating you've installed......
02-03-2014, 09:56 PM
#744
Nordschleife Master
Thread Starter
Stock computers, stock sensors. Fuel cooler fits and must fit and be run given the fuel flow rates. There's no heat problem anywhere, everything has the right clearance, thermal barrier coating, and shielding given the temp differences. The downpipe for example is actually pretty cool given the gas expansion in the turbine while the pressurized manifold is very hot.
02-03-2014, 10:45 PM
#745
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Solid motor mounts?
02-03-2014, 10:57 PM
#746
Nordschleife Master
Thread Starter
Nope. The motor and transmission mounts are stock style.
Everything is either designed to rock with the engine or has enough compliance and clearance for the motor rocking on the mounts. For example, the pump is attached to the oil pan. The manifolds to the head, turbos to the manifold, sumps to the turbo. One of the reasons why the sumps had to be redone from scratch was to regain the required clearance from the sway bar.
The same way, everything that has differing thermal expansion, has compliance built in. The downpipes have flex joints, including those on wastegate dump pipes which are cold most of the time and then heat up very quickly when the wastegates open. The air box is now bolted to the engine with steel brackets in a way that as the engine block expands with heat, the air box pushes ever so lightly towards the MAF housing and the boot.
John's pretty comprehensive about this kind of stuff.
Everything is either designed to rock with the engine or has enough compliance and clearance for the motor rocking on the mounts. For example, the pump is attached to the oil pan. The manifolds to the head, turbos to the manifold, sumps to the turbo. One of the reasons why the sumps had to be redone from scratch was to regain the required clearance from the sway bar.
The same way, everything that has differing thermal expansion, has compliance built in. The downpipes have flex joints, including those on wastegate dump pipes which are cold most of the time and then heat up very quickly when the wastegates open. The air box is now bolted to the engine with steel brackets in a way that as the engine block expands with heat, the air box pushes ever so lightly towards the MAF housing and the boot.
John's pretty comprehensive about this kind of stuff.
02-04-2014, 07:55 PM
#748
Nordschleife Master
Thread Starter
After it fires up, we'll make changes on at the time. We'll try to get it running with the current software at about the same boost and power levels as before. After that, we'll have to decide based on some high-school math whether install the new software first and the bigger injectors second, or the other way around. There's a good chance that we'll also run a set of camshaft tests with the stock engine, now that I have the adjustable LSA custom cams at my disposal. John's dyno will become handy.
After everything is tuned to perfection (or the stock engine destroyed, whichever comes first), it's time to pull the engine and start again with the low compression engine.
02-04-2014, 09:53 PM
#749
Rennlist Member
Are you guys doing all this as a one-off project, or are you hoping to develop a kit you can make available to others? You may have answered this question earlier in the thread (and I may have read the answer), if so, I apologize for asking again.
02-04-2014, 11:33 PM
#750
Nordschleife Master
Here's the starting point: http://www.kuhnperformance.com/model...928-twin-turbo
Includes all the exhaust, intercooler, intake, turbo's etc.
I don't think anyone will make a "kit" for what Tuomo's up to now with the new turbos, custom housing etc. - there just isn't much demand.
However his 700+hp earlier in this thread was achieved with minor modifications to the kit above (like the boost controller), and many hours of tuning and dyno time.