Fant en lang men interessant artikkel fra Chris i horsepowerfreaks for den som vil lese
"There has been a lot of talk about our built motors with our stage 2.5, 3 and stage 4 turbo systems, and I figured it was worth mentioning some of things we've learned along the way to help others save some money and a "lot" of headaches. Had we known these things I'm going to mention below we would have saved tens of thousands of $$'s.
As most of you have already heard, we don't let any cars leave our shop without being perfect. However, after the fact, we've had some turbo's fail which we've replaced, and have had a few other minor issues with our turbo systems that we've fixed on select customer's cars. Anytime these things happened we fixed the customer's cars, made improvements to the kit, sent any newly updated parts to customers that weren't affected but could be in the future, and improved our testing processes to prevent future kits from having any issues. This process has evolved our turbo systems to a level where we we now have more cars on the road than ever before along with virtually zero support calls. When our customers call now it's generally to talk about the cars they've spanked.
This week I decided to take our level of support one step further and correct a problem with "ALL" of our early motor builds even though our existing customers weren't complaining about it. Here's the reason.... We initially farmed my M3 motor, Ardika's motor, Richard's motor and My Tran's motor out to a machine shop that was recommended to us. We provided this machine shop with our built engine internals and installation specs, and asked them to build these motors to handle upwards of 1,000rwhp.
Once we got these engines back, we installed the head on each of them, installed all of the accessories on the engine, installed the engine in each car, bolted on the transmission in each car, filled all the fluids, installed the front clips and each car would smoke. At first we thought it was because the motor was still breaking in. So we would put a couple hundred miles on each car and in a couple cases, the smoke would go away. It would smoke under boost but we were told that the motor was set up loose and you'd rather have it smoke than seize.
The last engine we sent to them, Richard's, we literally had to remove the entire turbo system, remove and completely disassemble the motor 3 times to correct issues with the smoking. We also designed a fake turbo to bolt in it's place to run the car without a turbo to ensure it was the motor smoking and not the turbo as the machine shop was trying to lay blame on other things. Richard's M3 still smokes today and he's coming back from a long stint in Iraq and I'm not about to give him a car that smokes. Even more importantly, his car is going to be ready for him when he gets back.
The machine shop issues weren't just confined to engine work as they also screwed up Scott's head that required us to pull his engine out a few times to fix issues with an improper valve regrind that left too little clearance for the valve shims.
To date, I estimate those issues alone have cost HorsepowerFreaks roughly $30,000 with labor, tons of head gaskets, engine gaskets, oil, etc, etc and that doesn't even count the lost sales because we weren't able to work on other cars during that time. But that's just the beginning. Now that I have all of the 4 original built M3's in my shop (Ardika is selling his because he now lives in Singapore, My Tran came back for Stage 4, Richard is still in Iraq and my M3 is here) and they all burn through a quart of oil every 1,000 miles, I decided to rebuild all of their engines AGAIN.... "for FREE". None of these owners asked me to do this, I just can't stand the thought of knowing that we can fix these issues and not doing it for them.
During this fiasco, I had Brian at M&B come over and help us figure out the cause of this engine smoke. We sent the next few motors builds to him and after his machining process they didn't smoke. In fact, even during the break-in they barely smoked. Before I go into the details about these engines smoking, I want everyone to understand that in a turbo car where the turbo sits lower than the engine oil (like with the S54), anytime an owner runs their car very very hard and shuts the car off with very little cool down, they may get a puff of smoke the next time they start their car. That is not normal but can happen on occasion. If it does, it is because any oil not vacated from the oil lines can leak into the turbo exhaust housing after shut off if it's not completely pumped out. This is rare but you can tell it is the turbo because it only happens when you start the car and it only last for a second or two. We recommend letting the car cool down for atleast one minute if you've run the car hard as that is the only time we've ever seen this occur.
Now... onto the specifics of the smoking issues.
What we've determined is that these motors smoked for 4 different reasons:
1) The pistons rings were gapped larger than the piston manufacturer recommended
2) A conventional abrasive was used when honing the cylinders
3) A computer control machine to determine taper was not used.
4) The motors were not torque plated.
#1) Many engine builders that are familiar with lower end pistons add an extra measure of safety to their ring gap which was done to ours without our knowledge. This is because as the metal expands the gap closes and under extremely high temperatures as those produced by a turbo motor at high boost the ring can expand so much that the gap completely closes and it expands into the cylinder wall causing it to seize in the cylinder. Our pistons were spec'd from the manufacturer with a much smaller ring gap because the high quality of our pistons doesn't require this extra end gap. This allows the motor to be put together with a minimal ring gap so that cylinder blow by is virtually eliminated. This creates a much tighter motor that makes more power and keeps the oil where it belongs, inside the engine not inside the cylinders.
#2) These early motors were honed with a conventional abrasive. Conventional abrasives wear down and as soon as they start wearing, they start egg shaping cylinders. With low power applications without boost, this egg shaping in most cases won't affect engine performance or oil consumption. Machines shops that generally deal with the lower horsepower applications may not even know that their abrasives are egg shaping cylinders. It only takes a 0.001 inch difference from side to side to start costing performance, and on a high boost application as these abrasives are used on motor after motor, this egg shaping gets worse and worse. That may indeed by why our last motor they did was the worst by far. To combat this, our new engine builder, M&B, utilizes a super abrasive. This abrasive has 4 diamond holders on the tool that each hold 8 diamond inserts. This abrasive maintains it's tolerance over time and doesn't break down like the conventional abrasives do.
#3) The cylinder walls change shape over time. As you go up and down the cylinder, the diameter of the cylinder walls change a small amount. This is called the "taper". With a conventional honing machine the cutting edge takes off a specified thickness each time it goes up and down. Unfortunately, this thickness remains constant and any pre-existing taper is left after the honing is completed. M&B use a brand new Sunnen SV10 computer controlled honing machine. This machine eliminates this problem by removing all taper. It does it by sensing the minute reistance in the abrasive as it goes up and down the cylinder. As the taper decreases, the resistance goes up and this machine will go back to that area and remove the taper. When the honing is done on this machine and the diamond abrasives are used, the cylinders are perfect. No egg shape, no taper, and barely visible honing lines. Scott's and Brian's motors were done on these new machines with the correct ring gap and we saw very little smoke even during the break-in phase.
#4) The first motors were honed without a torque plate. On our stage 2.5, 3 and stage 4 motors, it is absolutely essential that the head doesn't lift on the engine. Many people running high boost applications have experienced this problem. Here's another trade secret. We monitor the head lifting by installing a pressure sensor in the cooling system. Anytime coolant pressure increases drastically and almost instantaneously during a pull, we know the head lifted. This is because once the head lifts, the combustion pressure is able to escape into the coolant jackets. Most people don't know this happened because as soon as boost drops the head seals back up as if nothing happened. For each engine and new boost level we do, we retorque the head bolts until no more coolant pressure spikes. This allows us to determine the minimum amount of torque to apply to the head studs that will still prevent the head from lifting. Then we use that torque spec for all future engines for each stage. Now you probably figure we tighten these head studs pretty tight and you're correct. Unfortunately when you do this, this torque literally changes the shape of the cylinder walls. Now these freshly honed cylinders that had no taper when they left the machine shop are now ovalized when you bolt your head to it. To combat this problem we're using a specially designed torque plate for the S54 engine. This torque plate (pictured below) is bolted to the engine with the same specs as the head. This puts the cylinders under the same loading that they see when the head is assembled and allows the machine to hone each cylinder so that it is perfect when the head is finally assembled.
I can't have our high end M3's burning oil. Our customers with these kits have paid a considerable amount of money to own the road and the last thing they should be explaining to people is why their car smokes under boost. I'm eating all of the expenses to correct the machining errors mentioned above and am replacing the rings, head gaskets and all other parts on these engines that need replaced, including doing a full break-in, oil changes, etc. I'm very happy that everyone's car was here anyway so we can get their cars running clean."
