dalesince59 Posted January 2, 2007 Share Posted January 2, 2007 One engine (l28et) had been run for 30,000 miles with roughly 75% of the coating flaked away. This engine had seen enough detonation to blow a copper head gasket with steel o-rings in the block, but there was no major damage to the stock pistons. This is very interesting. You may have just proved that your coating job did work for you. The coating was sacrificial and your pistons still intact with no holes in them or worse, conecting rods broke loose from the pistons there by saving some major damage and expense. I don't know of any materials used in our automotive field that will hold up to an oxy-acetylene torch blast for an extended period of time, and this is exactly what happens in an un-controlled combustion cycle [EXPLOSION AND EXTREME PRESSURE SPIKES INSTEAD OF EVEN BURNING AND AN "EASIER" RELEASE OF ENERGY AND THE RESULTING PRESSURE WAVE] Pressure good! Explosions bad! at least in engines! Your thoughts on cost versus intended usage and their benefits is a very good point.This applies to every part we may use. Unlimited funds do not necessarily guarantee success in this area and there is no '"sane ''reason to spend money for something if it will not accomplish it's purpose. IMHO dale Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted January 3, 2007 Administrators Share Posted January 3, 2007 First off, Engine failure analyses is truly an art form. I am by no means an expert in this field, but as an engine builder/machinist, I have had many opportunities to see lots failures first hand, (not ours, but those of others), inspect, confer with engines owners and help make right what went wrong in the first place, if it was assembly or machining related. Pictures on the web is definitely not the way to accurately evaluate a failure, but we can at least narrow down the possible causes in an effort to keep from repeating the failure in the future. As for my own engine failures, the worst failure I was personally responsible for was a custom radical Briggs & Stratton 5HP that I built for Ron Tyler and myself to race at the local autocross, (thank god it wasn’t a customers) and I succeeded in turning that loud buzzy one holer into a grenade in the middle of an Autocross a few years back. It ran pretty good up to that point… … Skirt Scuffing… It would be nice to see more detailed pics of the piston skirts in question. Based on that one picture, it looks more like scratches, such as small debris, i.e. large dust/small dirt particles from a not so clean assembly, not so much scuffing. Odd thing here is Hoke mentioned the cylinder walls themselves looked great, no scratches etc. Without more info, pics, etc, I’m at a loss as to what actually caused the skirt scratching/scuffing. Skirt Scuffing usually covers broad areas of the skirt area with scratches. Hokes piston looks like it only has scratches with normal skirt wear surrounding the scratches, not really scuffed. If it was caused from Excessive combustion temps that in turn cause the skirts to swell, this manifest as very uniform “scuffing” mostly just below the region of the oil ring or the “four corner” areas surrounding the pin boss. Depending on the severity will determine on how much metal transfer took place. Remember, excessive combustion temps doesn’t mean excess coolant temp. Excess combustion temps are lean conditions in the “combustion chamber” and happen at all engine coolant temps. Excess coolant temps will cause the skirt to scuff around the mid section of the skirt itself, not just below the oil rings like excess combustion temps cause. Hokes scuffing looks more like debris and if the scratches have raised lips at their edges, then my guess at this point is debris… But again the cylinder walls don’t show the same… Hmmm…. Main bearing… I’d REALLY like to see close up quality photos of ALL of the bearing shells, upper and lowers, Mains and Rods. That one pic sure looks like there is some flaking taking place, i.e. fatigue. If it is fatigue with such low miles, that would definitely be detonation or REALLY REALLY cheapo bearings with very poor bonding during the manufacturing process. Being as the cylinder head had the small pitting around the head gasket fire ring indicating detonation at least on some level, chances are it is fatigue from violent uncontrolled combustion….. Rings stuck in the ring lands… Either lots of carbon build up binding the rings or the rings lands themselves are collapsed. If the top rings were stuck, without seeing them first hand, I would guess the top ring land was collapsing due to extreme cylinder pressures, i.e. detonation and if that is the case, the only role those pistons could fulfill in their future life is as clock holder or paper weight. If the ring lands are collapsed ANY degree what so ever, those rings have been compromised and the piston is no good. F.O.D. Due to the size, shape, uniformity, and the lip surrounding the craters in the piston ridge and matching region on the cylinder head, I would guess that the piston and cylinder head were playing a high stakes game of ping pong using a very round object of a much harder compound than the piston and head. Who knows what it was and at this point who cares as it shouldn’t happen again, (just be sure to clean and inspect the induction tract between the air filter and intake valves really good for F.O.D.), and the fact that it is concentrated on one side of the chamber means squat diddly. The speed at which all that took place and the air flow in and out of the chamber could very well influence where that little sphere landed as it was being squished between the cylinder head and piston. The fact that something did make its way through the chamber does raise a concern. Being as this is a Turbo engine, “valve seating” is even more critical than N/A engines as the valve run MUCH hotter and need to dissipate that extra heat for valve cooling reasons to prevent burning a valve, in particular the exhaust valve. If this F.O.D. did get stuck in between the valve face and valve seat, it could, but not necessarily, may have left similar yet smaller indents in the valve seat and valve face, thereby compromising valve face to seat interface which doesn’t allow the valve to fully dissipate its heat into the seat and as result, becomes much more susceptible to burning. To be sure of this one way or the other, you would have to remove the valves to visually scrutinize the seat/valve surface for deformation from FOD. No matter what, ideally you would want to reface the valve itself just to be sure it didn’t get bent from being propped open on one side due to the little ping pong getting caught between the valve and seat. 240hoke. I realize this isn’t news that you wanted to hear this late in the game as I gather you put the engine back together with those same pistons etc. If there are any issues with the piston ring lands, it should show up as poor cylinder sealing, blow by, etc. I honesty hope that you are able to get it back up and running close to what it was prior to this event. Good luck and please keep us posted… Paul Ruschman Quote Link to comment Share on other sites More sharing options...
240hoke Posted January 3, 2007 Author Share Posted January 3, 2007 Hey BRAAP, Thanks alot for your input. And your exactly right its not the news I wanted to hear. I did do a visual inspection of the valves on #6 as best I could with the head still together. In hindsight I should have taken the valves out and double checked everything and I may do so before I put the motor back in. Your right the cylinder walls looked fine, and except #5&6 the piston wear looks great. The scoring/scratching also conincided with the side the FOD was on. The rings were definitly stuck and there was absolutly no carbon build up these pistons are clean as a whistle below the top. Im sure they were compressed due to detonation. Im not so sure its the end of the pistons though I didnt have to remove much material at all to get the ring gaps widened. But as much as I hate to say it, the L28 isnt worth it too me. I have everything back together and I plan to push it to its limits. Perhaps it will hold perhaps not, but lets just say I have every intention on trying to hit 450-500hp -- hopefully i will have some dynocharts to post, or perhaps some more pictures to analize If it blows I guess Ill find another motor to learn how to work on I will update you guys with a compression check and how it runs as soon as I can. I start work next monday and will be able to use their machines to make my tranny adaptor if all goes well. I may wait till I get that done to drop the motor in. I also drew up an exhaust flange today in solidworks while I had the motorout so I may play with something there as well. ANyhow thanks for the advice everyone. Quote Link to comment Share on other sites More sharing options...
woldson Posted January 3, 2007 Share Posted January 3, 2007 dangit i got to get my wife to help me for pic posting sorry, btw he has a b16a honda at that compression, yea i tell him he is insane but he wants the power to spool turbo easily oh well. Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted January 3, 2007 Share Posted January 3, 2007 what?! Quote Link to comment Share on other sites More sharing options...
stagefumer11 Posted January 3, 2007 Share Posted January 3, 2007 Actaully if you read alot of the holset threads on the DSM forums, And the honda ones. There seems to be alot of people running high compression turbo motors these days. Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted January 3, 2007 Share Posted January 3, 2007 Actaully if you read alot of the holset threads on the DSM forums, And the honda ones. There seems to be alot of people running high compression turbo motors these days. Sure, with dual overhead cam cross flow designs... Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted January 4, 2007 Administrators Share Posted January 4, 2007 Hey BRAAP, ...... But as much as I hate to say it, the L28 isnt worth it too me. I have everything back together and I plan to push it to its limits. Perhaps it will hold perhaps not, but lets just say I have every intention on trying to hit 450-500hp -- hopefully i will have some dynocharts to post, or perhaps some more pictures to analize If it blows I guess Ill find another motor to learn how to work on I will update you guys with a compression check and how it runs as soon as I can...... Austin, Ah… So the L-28 isn’t spinning your prop, lighting your fire, spooling your Turbo, smoking your tires, turning your crank, rowing your gears, (or any other silly anecdote you can conjure),… Soooo.. you obviously have plans for some other power plant.... Care to let us in on it? …. . . . . . . . . Please? BTW, Looking forward to reading how much you are able wring out of the wounded L-series soldier… Good luck, Paul Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted January 4, 2007 Share Posted January 4, 2007 Austin has mentioned a RB swap before...That would sure be mean Quote Link to comment Share on other sites More sharing options...
LineC Posted January 4, 2007 Share Posted January 4, 2007 I wish I had a hype man Quote Link to comment Share on other sites More sharing options...
240hoke Posted January 4, 2007 Author Share Posted January 4, 2007 hehe it might jsut be something with more cylinders, but im not sure myself. We will see what hte L can do first. I really love these motors. Quote Link to comment Share on other sites More sharing options...
Sparks280zt Posted January 4, 2007 Share Posted January 4, 2007 We discused it last night, its between a 12 valve Cummins or a 6.6 Duramax. Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted January 4, 2007 Share Posted January 4, 2007 hahah suuree.. im willing to bet 2JZ Quote Link to comment Share on other sites More sharing options...
bubbleguinea Posted January 4, 2007 Share Posted January 4, 2007 or you can go the minus two cylinder route.... a b18 out of an early 90's integra with v-tech would be fun.... just kidding. Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted January 5, 2007 Share Posted January 5, 2007 I think it will be another L series motor...but with another 2 cylinders added on...and an aluminum block Quote Link to comment Share on other sites More sharing options...
ProjectSR20 Posted January 13, 2007 Share Posted January 13, 2007 Ok, I don't want to just hop in here and take over this thread, but the discussion of the ceramic coating has me a little interested. Could part of the problem that people are experiencing be due to overheating the cylinders? It seems that everyone that said they had problems with it peeling also said that they had detonation. From what I understand detonation can cause massive spikes in both temp and pressure within the cylinder. If this is true would it be too much of a stretch to think that the extreme temps and pressure is what caused it to flake. Is the coating really designed to take that kind of abuse? I am just throwing this out there hoping someone can comment. Please resume your regularly scheduled thread. Also, sorry to hear about your motor troubles Austin. I have loved that Z since the first time I saw it. I am sure you will be back on the road soon though, with more power!! Good luck to you sir. Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted January 13, 2007 Share Posted January 13, 2007 I don't think temperature can cause the ceramic coating to come off. Aluminum melts at aprox. 1200 degrees F. I think that the ceramic could withstand that pretty easily. The problem could be the detonation shockwaves though... Quote Link to comment Share on other sites More sharing options...
zguy36 Posted January 15, 2007 Share Posted January 15, 2007 So, I posted a bit earlier in this post slinging some hate in the direction of ceramic coatings. I would like to retract all previous statements and shed some much better light on the situation. Here is the history of my motor. The first 30K miles put on this engine were running the sketchy stock fuel injection and about 17psi of boost. As you all know, this can't be done on the stock setup without a few bandaids. I ran water injection, and a seven injector actuated by hand to dump more fuel. This setup would experience detonation on a regular basis. This setup had all stock internals, except for a steel o-rings with a copper head gasket, and ceramic coated stock pistons. The detonation on this setup was so regular that I had broken ten or so spark plugs, and also blew the copper head gasket. The next 10k miles were run much more sanely. I put on a megasquirt, brought the AFRs down from 17:1 under boost to 12.5:1 under boost. Still running same boost. When the copper head gasket blew, I replaced it with a steel one, but also noted extremely bad flaking on the piston tops. I thought this was the ceramic coating coming off. I scraped the bad places off and put it all back together. So, now that the engine is down for a rebuild (worn thrust bearings with .25" axial crank play), I decided to do rings along with bearings. When cleaning the piston tops off, I found that the ceramic coating was still there! It had survived the massive amounts of detonation. The only reason I didn't find it there is that the color had changed from the light gray to aluminum color. When wire brushing the piston tops off, you could see low spots with machining marks under them. The cermic was a pain to remove, but it held up. So, as far as saying that ceramic coatings can't handle abuse, that is just plain wrong. As far as the benifits from using them, that is much more difficult to determine. As far as my setup is concerned, I will re-coat my pistons again when I put it back together. You can't beat a good diy coating price wise! The coatings were CBX from http://www.techlinecoatings.com Quote Link to comment Share on other sites More sharing options...
woldson Posted January 17, 2007 Share Posted January 17, 2007 Its kinda like running synthic oil or oil additives, they work but its kinda unmeasureable. Could be the reason engine ran forever, but if the oil pump breaks, how much damage was advoided, hard to say. Cost not too high, so it creates cheap insurence! Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted January 17, 2007 Share Posted January 17, 2007 Ceramic coatings, if not applied correctly will not last! If your experiencing problems then either your detonating the engine, or it wasn't applied correctly IMO. In my diesels I run ceramic coated piston tops, 500,000 miles later they look just like they did when they went in, well plus alittle carbon. I run diesel, 30 psi boost, 200 psi fuel injection pressure, on 17:1 compression, generate 1800lb-ft of torque and over 500HP to the tires! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.