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The existing exhaust design (pictured here https://rennlist.com/forums/928-foru...l#post13869242) that I call Silent Night is attracting some police attention in Kentucky and neighboring states. Even when the car is outside the radar range, the police can still estimate the location, direction, and ball-park engine speed from the exhaust sound. Google and the Russians are automatically tracking the location of the car based on the exhaust noise. I christened that exhaust design Silent Night because once you drive the car with that exhaust you can't hear anything else for the rest of the night because of the temporary hearing loss. It flows really well, though, because it only has straight thru mufflers and mandrel bent pipe sections.
Because of this, we're now planning a second iteration of the exhaust design called the "Celebration of Lights." The Celebration of Lights exhaust or, for short, Diwali exhaust will be a modular second tail section. Like an RMB, or more accurately an "RMB delete". This modular second tail section will have an additional Borla muffler can in the stock location and will merge the flow paths and pulses at that location. The existing center section will be reused. This exhaust will be called the Celebration of Lights or Diwali because when you drive with thru a residential neighborhood with it at night, a light comes on in every house. While loud, this Diwali exhaust will be quieter than the Silent Night. The rear muffler will be sized not to increase back pressure meaningfully, and the bends will continue to be mandrel-bent gentle-radius turns.
As a completely separate effort, I'm working on a full new exhaust design that will be called the Necromancer. (Yes, you guessed right, the name comes from the idea that if you drive by a graveyard with this exhaust on, the noise wakes up the dead.) The Necromancer will have a 4" oval center muffler from Spintech, specifically of the Race Bullet variety, which is a muffler in name only but more importantly an efficient way to terminate pipes from the wave perspective and to combine pulses from the banks. The center "muffler" will then split into two 3"/3" I/O large Magnaflows mufflers on both sides. The unequal-length divorced flow paths will then combine again into a single 4" pipe via a Y-merge and there will be a 4"/4" I/O large Magnaflow muffler at the back. This will likely be next winter's effort.
I was reading, expecting 'Celebration of Lights' to be something more like:
That's a good one, and also works! Bam-Bam-Bam, bedroom lights come on, phones start ringing at the station, and the blue lights appear in the rear view mirror. Let's call the blue lights the "after party".
A runner up for the exhaust names was "Agent Zero M Sonic Blaster." That's an old toy, and the consumer reports review of it lines up perfectly with how they'd review my twin-turbo exhaust:
"The Mattel Agent Zero M Sonic Blaster 5530 fires compressed air with a deafening blast. Our measurements top out at 157 dB–above a level that can do permanent damage to the hearing of an adult. We rate the toy Not Acceptable."
ptuomov
I must say that the insights you, John and the engine builder display from post #1403 onward could benefit a group like m5board.
After much discussion by many knowledgeable people we still are not sure on the specifics causing premature rod bearing wear.
The kind of experimenting, and testing you have done is what is missing there; perhaps due to a much more expensive power unit.
You have touched on viable root causes of bearing wear for the V-10 8200 rpm motor in the form of balanced oil feed and evacuation as well as ring flutter (my stroker 6.0 v10 uses a quart every 1200 miles but perhaps still needs more break in time).
Well done, I will be following closely.
Not to worry I will not link your thread on m5board, in order avoid even more noise than you have seen on rennlist. LOL
ptuomov
I must say that the insights you, John and the engine builder display from post #1403 onward could benefit a group like m5board.
After much discussion by many knowledgeable people we still are not sure on the specifics causing premature rod bearing wear.
The kind of experimenting, and testing you have done is what is missing there; perhaps due to a much more expensive power unit.
You have touched on viable root causes of bearing wear for the V-10 8200 rpm motor in the form of balanced oil feed and evacuation as well as ring flutter (my stroker 6.0 v10 uses a quart every 1200 miles but perhaps still needs more break in time).
Well done, I will be following closely.
Not to worry I will not link your thread on m5board, in order avoid even more noise than you have seen on rennlist. LOL
Others are too polite to say this, so I will. Almost none of the testing you refer to was done by me! It's all John and the builder of the blue engine. I've just been thinking about these issues a lot and done some modeling on the computer. And of course, speculated wildly about the issues on Rennlist.
By the way, I owned one of those V10 M5's. It drank a lot of oil. But as long as the oil isn't going out from the breather into the intake, who cares? If it's just oil consumption without any ill effects related to it, why not just fill it up every now and then? If the rod bearings get beat up, then that's another thing altogether...
Others are too polite to say this, so I will. Almost none of the testing you refer to was done by me! It's all John and the builder of the blue engine. I've just been thinking about these issues a lot and done some modeling on the computer. And of course, speculated wildly about the issues on Rennlist.
By the way, I owned one of those V10 M5's. It drank a lot of oil. But as long as the oil isn't going out from the breather into the intake, who cares? If it's just oil consumption without any ill effects related to it, why not just fill it up every now and then? If the rod bearings get beat up, then that's another thing altogether...
Tuomo is coming up with all those wild theoretical calculations/ideas (think someone calls it internet engineering) and then it is up to us poor ordinary guys to try to put it into practise. What would we be without a smart guy like Tuomo?
By the way does not Clevite supply an upgraded rod bearing that can be installed in the M5 V10 like they do for BMW motorcycles and the 928 also having problems with rod bearing failures?
"By the way does not Clevite supply an upgraded rod bearing that can be installed in the M5 V10 like they do for BMW motorcycles and the 928 also having problems with rod bearing failures?"
Yes, a buying group B.E. bearings orders them from Clevite to their own spec with larger clearances.
however not many cars with any kind of mileage on them yet.
Thus yet to be proven as an upgrade.
Some of the consensus is tight OEM bearing clearances are to blame, I am not convinced that this was a misstep by BMW Engineers.
Modern synthetic oils can resist the additional shear forces that tight clearances entail thus taking advantage of combustion loads and deceleration loads being spread to a larger surface are along bearing.
The proof will be in the testing.
The development of v10 as in the 928 is nucleated by a similar "smart guy like Tuomo" with exceptional results furthering the platforms after many iterations of the original ideas by the hard work of the likes of John and Mike (with his incredible machining capability).
Without an original idea the ball never gets rolling, thus in the formative stages I never critique an early stage original idea, instead help support it till all parameters are nailed and a complete solution is achieved by the Team.
It is all to common on any forum that the status quo feels threaten by "a smart guy" with pot shots taken in early development stages being effective in having smart guy move on.
"By the way does not Clevite supply an upgraded rod bearing that can be installed in the M5 V10 like they do for BMW motorcycles and the 928 also having problems with rod bearing failures?"
Yes, a buying group B.E. bearings orders them from Clevite to their own spec with larger clearances.
however not many cars with any kind of mileage on them yet.
Thus yet to be proven as an upgrade.
Some of the consensus is tight OEM bearing clearances are to blame, I am not convinced that this was a misstep by BMW Engineers.
Modern synthetic oils can resist the additional shear forces that tight clearances entail thus taking advantage of combustion loads and deceleration loads being spread to a larger surface are along bearing.
The proof will be in the testing.
The development of v10 as in the 928 is nucleated by a similar "smart guy like Tuomo" with exceptional results furthering the platforms after many iterations of the original ideas by the hard work of the likes of John and Mike (with his incredible machining capability).
Without an original idea the ball never gets rolling, thus in the formative stages I never critique an early stage original idea, instead help support it till all parameters are nailed and a complete solution is achieved by the Team.
It is all to common on any forum that the status quo feels threaten by "a smart guy" with pot shots taken in early development stages being effective in having smart guy move on.
In the early 70´s BMW came out with a new generation of motorcycle engines having plain bearings. I started to modify these engines for more power and for the first iteration of the flat twin 750cc engines I had no major problems but with the introduction of the R90S 900cc, for which I even more extensively modified the engine to 1000cc and 9000 rpm, I started to get con rod bearing failures. After much trial and errors the final solution was to exchange the soft Glyco rod bearings with hard Clevite bearings from a car engine which after some machining could be made to fit the motorcycle engine. Those Clevite bearings were not the race quality (TM-77) but a standard quality (TM-1) but still a great upgrade of the Glyco bearings.
For the 928 we have all heard of similar problems with the soft Glyco rod bearings so the first thing I did when being aware of the 928 rod failures was to search for a race quality rod bearing. I came up with a Toyota rod bearing CB-1628HX from Clevite that can be fitted with some minor modification to the rods. H stands for High Performance (quality TM-77) and X for increased oil clearance of 0.061 to 0.079mm. Michael Mount has a thread of the same modifications for the 944 and 968 engines. https://rennlist.com/forums/944-turb...aring-fix.html
Concerning the BMW M5 V10 engine I am not much informed but I did find this. http://www.m5board.com/vbulletin/e60...s-s65-s85.html
Everybody here except one party are very happy about our "smart guy", unlike us ordinary guys who wants to know what works he likes to find out why it works.
Åke
Last edited by Strosek Ultra; 01-14-2017 at 01:47 PM.
I've been recently trying to be clearer about the degree of confidence that I have in what I write here: what is an interesting idea, what's a fact, what's proven solution, etc. I think it's important to clearly separate facts, hypotheses to be tested, and theories why facts are what they are. I'll try to do an even better job in the future making those distinctions.
On the twin-turbo front, the news is that the ECU's think the engine is warmer at start-up than it actually is, which means that there temp II sensor is bad or somehow has an interesting bad connection. Next step is to try to swap that temp II sensor to a new one and verifying it grounds correctly, even before thinking about debugging anything else.
One interesting thing is that with the new cams and the new exhaust manifold, the turbines are already spinning at idle, both based on the stethoscope and the gauge. With the stock S4 cams and the previous exhaust manifold version that didn't direct pulses as well towards the turbine, the turbine speed at idle read zero on the gauge.
That's extremely strange that the turbine speed was zero. Doesn't take much to spin them so I would expect any exhaust flow would get them going. Was the wastegate wide open at idle?
That's extremely strange that the turbine speed was zero. Doesn't take much to spin them so I would expect any exhaust flow would get them going. Was the wastegate wide open at idle?
The wastegate was not open. It's spring and boost driven anyway, so we don't have the control option of forcing it open without pressure in the manifolds.
(As a side point, there's in some circumstances an efficiency gain from keeping the wastegate open until some rpm and throttle angle. But that's the sort of emissions masturbation that only the government can force a car company to spend money on.)
It's interesting that the turbo idle speed in the previous iteration was so low that it didn't register on the gauge needle. We didn't ever log the value or anything, just looked at the gauge so it's not like this is a precise measurement.
Personally, I attribute the change to earlier EVO and exhaust manifold shape.
John's running some tests so we can get the blowby meter calibrated for the right range. (That's the total blowby from the cold engine at idle displayed on the meter.)
The first set of tests will be about total blowby and not about the breather capacity. All other ports are sealed and all the blowby is run thru the meter.
The first interesting individual test will be measuring the blowby with the intake plenum at atmospheric pressure (about normally aspirated equivalent) and at 4000 rpm (about normally aspirated torque peak). Depending on what we see when we try that, the sensor range will be calibrated differently.
01-13-2017, 12:57 PM
