Engine failed...again

[float_6969]

Bah, I'm so annoyed right now. So here is the back story if you don't know how things have been going for me the last couple of years;

I had an oil filter fail. The "guts" of the oil filter blew into the motor, ruined the bearings caused some minor wiping on the rod journals and ruined the head. I had a 4 port head just laying around, so I port matched and polished it, dropped in my HKS 264's that I had lying around and my old school cam gears and a new set of lifter. The cylinders were OK, just had them deglazed. The crank was in good enough shape that I had it polished up and replaced the bearings. There were some issues with a check valve in the block that supplies oil to the head, but I got that sorted out. I also replaced the oil pump. The pistons were fine as were the stock rods. I slap it all back together and off I go. Now I haven't driven it much, as the suspension was shot and I replaced it. I've also been fiddling with the intercooler setup because it wasn't working like I wanted it to. Well I finally got all of that sorted out and was out beating on it a few months ago and the engine felt "off". I can't describe it any better than that. I've had this engine for 8 years now, and I know it well, and something wasn't right. I knew the cams were different, and I wasn't used to that, and I had also changed the turbo, so I had written the difference off as that. Well as I'm doing some research, I find out that my HKS cams aren't just plug-n-play and they need indexed. So I figured maybe that was the issue. So I buy a degree wheel and pull the plugs out so I can find true TDC so I can degree the cams. This is what I pulled out of the #4 cylinder...


That's a very expensive NGK Iridium spark plug with a VERY melted electrode and a big chunk of the porcelain insulator missing. And before you give me crap about Iridium plugs, I ran this same plug for YEARS with out issue. One of my customers used to be a developer for NGK and was one of the lead designers of this plug. He does a lot of very high HP engines and this is the plug he runs on EVERYTHING.

Anyway, so my first thought is, "Where the hell did that metal and porcelain go?!?!" So I did a compression test;
cyl #1 - 155 psi
cyl #2 - 155 psi
cyl #3 - 155 psi
cyl #4 - 140 psi
Great. Something is fvkd up. I just spend a good chunk of change having a 5 angle valve job done and I REALLY don't want to have a ruined valve/valve seat. So I pour some oil in the cylinder and retest. #4 compression goes up. So there is an issue with the rings sealing. So I get the #4 cylinder to TDC and I can see some marks on the top of the piston. Blech. Time to pull the motor. So out it comes and I pull the head off. This is what I find...



That is the marks I saw through the plug hole. The top of my custom 10:1 compression CP pistons is damaged pretty badly. So I rotate the piston down the bore and see this;



That dark line is where the steel in the cylinder wall discolored from something rubbing up and down on it. You can't see it in the picture, but there is also a DEEP groove in the middle of that line. Like, see it with your eyes up close and you can feel it with your fingernail kind of deep groove.

I haven't pulled the valves out of the head yet to see if they were damaged. The combustion chamber looks fine though, so I think the "stuff" got jammed between the piston and cylinder and just ground into the cylinder wall.

I'm at a loss for what caused this. Melted spark plug electrodes come from REALLY high EGT's and the other plugs look fine. As you can tell from the porcelain, I had the tune pretty rich, and the plug was cold enough that it wasn't burning anything off the porcelain.

So now I'm in a spot where the engine is going to have to be bored out AGAIN. I'm already at 84mm. That was a custom piston from 5 years ago. IDK if CP still has it on file. If they don't, I'll have to send one of these in to get it replicated (the high compression with E85 is a blast and I'm not giving it up). OR, I buy another block, have it bored to 84mm. That's assuming that piston is OK. I haven't pulled it out yet to see what kind of shape the skirt is in. It may be ruined.

Just feeling pretty frustrated right now. Mostly because I don't know what caused this. I have a full set of gauges and the AFR's were never lean under throttle and the EGT''s weren't terrible. They could get a little high during cruising conditions, but I was assuming that was from the cam timing being off and not from improper combustion.

The last thing I want is to go to the trouble to put all this together and not find the original problem and fix it, and just have this happen again.

[Sideways s12]

s*** hope everything works out and you get back on the road.

[themadscientist]

Time for the franken two liter. I just shipped some L stuff back from the states so I have a shipping company I can talk to for an estimate.

[boost_boy]

Man, this blows donkey sausage. Something as small as that can do so much mechanical damage as well as financially punching you right in the soup coolers. Though I've never had that happened me, between 1999 and and 2000, I've trashed some pistons, scored some cylinders and blown some headgaskets, so I understand where you're at as well as how you're feeling. My suggestion, get another block and start from there. Your piston might be okay seeing that the chunk of plug has to make it past the rings to get to the piston and may have gotten ground to nothing being caught-up between the rings. Continue to do what works for you and charge this one up to the game as schitt happens. I sold my iridium plugs as I just didn't like them for my application.

[float_6969]

Time for the franken two liter. I just shipped some L stuff back from the states so I have a shipping company I can talk to for an estimate.

LOL, I was just thinking this last night after I posted this. I'll email you now...

[float_6969]

Man, this blows donkey sausage. Something as small as that can do so much mechanical damage as well as financially punching you right in the soup coolers. Though I've never had that happened me, between 1999 and and 2000, I've trashed some pistons, scored some cylinders and blown some head gaskets, so I understand where you're at as well as how you're feeling. My suggestion, get another block and start from there. Your piston might be okay seeing that the chunk of plug has to make it past the rings to get to the piston and may have gotten ground to nothing being caught-up between the rings. Continue to do what works for you and charge this one up to the game as schitt happens. I sold my iridium plugs as I just didn't like them for my application.

LOL, soup coolers, that gave me a chuckle. Thanks Dee. I'm with you on the block. This engine has been "cursed" since I was rebuilt the first time. I've fought low oil pressure since the first rebuilt and was still fighting it when this happened. Before all of this happened, I actually spent a lot of money on some nice, and VERY accurate digital micrometers and a bore gauge (both accurate to +/- 0.00005") because I was going to tear the motor down again to measure the oil clearances myself (I've used plasti-gauge on the last 2 rebuilds and the rod bearing clearances are REALLY loose). I guess I might be using them on the new block instead, LOL.

[Buddyworm]

Cracked porcelain might mean detonation. http://www.stockcarracing.com/techartic ... ark_plugs/ It's also cylinder #4, which is notorious on these engines for receiving poor airflow, isn't it?

Did you dial in your CAS properly? On the exhaust side maybe you ran into a problem with the tang being aligned differently at TDC versus the stock cam, leading to excessive ignition advance?

Or maybe just old gas?

[boost_boy]

Cracked porcelain might mean detonation. http://www.stockcarracing.com/techartic ... ark_plugs/ It's also cylinder #4, which is notorious on these engines for receiving poor airflow, isn't it?

Did you dial in your CAS properly? On the exhaust side maybe you ran into a problem with the tang being aligned differently at TDC versus the stock cam, leading to excessive ignition advance?

Or maybe just old gas?

He's using a standalone engine management system that has no use for Nissan's crank angle sensor. However, that is the results of detonation and it is never good when it happens.

For Ryan:Why in the hell is your compression so low? With those domed pistons you should be in the 9ish:1 to 10:1 compression ratio range (180-210psi).

[float_6969]

Cracked porcelain might mean detonation. http://www.stockcarracing.com/techartic ... ark_plugs/ It's also cylinder #4, which is notorious on these engines for receiving poor airflow, isn't it?

Did you dial in your CAS properly? On the exhaust side maybe you ran into a problem with the tang being aligned differently at TDC versus the stock cam, leading to excessive ignition advance?

Or maybe just old gas?

I suppose it could have detonated and I never heard it, but there are no signs of detonation on the head on any cylinder. My experience has taught me that these motors have issues with the #3 cylinder, but that was with an 8 port head, not a 4 port, so maybe that makes a difference. There are signs of detonation on some of the pistons, but they looked like that when I pulled it apart. When I first put this motor together, I was trying to run it on pump gas, not realizing I had 10:1 compression (I thought I had 9.5:1).

As Dee said, there is no CAS, so that's not an issue.

No old gas. It's E85, and it had a BUNCH of Stabil in it because I knew it was going to set for a while.

He's using a standalone engine management system that has no use for Nissan's crank angle sensor. However, that is the results of detonation and it is never good when it happens.

For Ryan:Why in the hell is your compression so low? With those domed pistons you should be in the 9ish:1 to 10:1 compression ratio range (180-210psi).

I don't know. I was surprised by them as well. I think the person who built the bottom end over-gapped the rings. The place I took it to last time has gone out of business. I used the place I used because they had a good reputation for head work. Apparently the bottom end work isn't as good. The last time the engine was built, the compression was dead on 210 psi across the board, and even when I tore it down from the failed oil filter, it was still around 200 psi after around 40K miles. I also bought a really nice ring grinder so I can gap the rings myself. I'm getting tired of spending money to have quality work done and getting crap work done.

[AFSil80]

I'd offer up my spare block, but when an intake valve guide cracked apart in my #3 cylinder, it made the same kind of mark on the cylinder wall...unfortunately for my piston and head, it didn't pass through.





If you're interested in just getting a block, I can snap some pictures for you. It's sitting on an engine stand doing absolutely nothing.

[dash]

that really sux
sounds like your first time with the hks 264s, so you shouldn't still see the same 200s, I'm guessing?
.....especially if not dialed in.

perhaps stabil "preserves" fuel, but does it effect (i.e. lower) E85 octane ?

[float_6969]

If you're interested in just getting a block, I can snap some pictures for you. It's sitting on an engine stand doing absolutely nothing.

I may be interested, but I'm trying to get a block I paid for years ago that's been sitting at TMS's house shipped over if I can afford the shipping. If not, I'll hit you up.

that really sux
sounds like your first time with the hks 264s, so you shouldn't still see the same 200s, I'm guessing?
.....especially if not dialed in.

perhaps stabil "preserves" fuel, but does it effect (i.e. lower) E85 octane ?

That's a good point about the 264's not being dialed in. If the overlap was high, I would loose compression from that.

I don't know if it lowers octane, but the engine was never run hard. Max of 5 psi on a big T4 turbo. The more I think about it, the more I'm wondering if the cam timing caused this. That's the main thing that I kind of glossed over. I made an assumption that I could just drop them in and they would be fine. I had problems with high EGT's from the start, but didn't know that until later. Probably after the porcelain had cracked. But I didn't know and kept driving it until completely chipped a piece off and landed me where I'm at.

[boost_boy]

I just don't know if the HKS camshafts need indexing. Remember, I run HKS cams (264 8.5mm intake and 272 8.5mm exhaust) and though I have had a slightly lower compression issue with the #1 cylinder in the past, I've also had much success as well. And even doing an oil test on the cylinder didn't bring the compression up, ao I had the head re-done. I've always had some kind of issue with this head and cam combination, but again, I've also had much success. I do know that when I put another head on the engine, everything wasd back to normal. But when I put the ported head with the HKS camshafts, weird things happened. Something to look at, but I wouldn't go crazy with the indexing notion just yet. You can always do a comparison with stock cams against the HKS pieces to see what happens to your compression.

[themadscientist]

All cams require indexing. This it degree them in to what they are supposed to be set at. Not doing this will leave them off a degree or two, but not enough to cause engine dame unless you are running some ridiculous duration and/or lift. The HKS cams are mild. There's zero chance they are the cause of this.

[r34 gtr]

Aw weak! Sorry to hear that, bud.

Do you have an EGT gauge? I cracked a ring land at 10.5:1 AFR because the ecu pulled so much timing I was sitting pretty with an EGT 1950F.

Holler at me if you really need a block.

[float_6969]

Well I had cam gears on there, but I was just going to use them for tuning on the dyno, so I just sent them eyeballed in the center. I didn't think that would be enough to cause problems, but I don't know what the high EGT's were from either. I know the timing was on. It's not hard to check on an SDS. The highest EGT I ever saw was about 1500°, but that POST turbo, so it was obviously much higher in the combustion chamber. BUT it was at cruise, not under load, so I wasn't too worried about it because I knew it was on the lean side (around 15:1 AFR). But I didn't get the EGT gauge until after I had been running the motor for a while, so I have no idea what was going on before that.

[TheMAN]

your tune maybe fine and detonation may not have killed the plug/engine... preignition may have... they are very different things although they both are very evil to engines
neither one can be easily heard if your exhaust or intake is loud, especially if you have the radio going inside the car... this is why on any high strung car, it is best to have some sort of knock detection system so that you can either "see" that it's happening (TurboXS Knocklite) or that it automatically pulls timing for you to attempt saving the engine (J&S Safeguard)... these systems pretty much only work for detonation and not preignition though... never trust the stock knock sensor or ECU's algorithms to detect knock... most stock systems are NOT aggressive or fast enough... they are designed to work fine on a stock motor and YMMV when you start modding... I've seen many different engines get damaged or blown up running only a stock knock sensor after everything under the hood got extensively modified because the stock system couldn't keep up and the car was so loud that the driver couldn't hear anything until it was too late... I hear this from people all the time "naw, I don't need a knocklite, I will use my ears and right foot when when I hear the engine ping"... famous last words! lol

don't forget... E85 is not the magic pill to a fast car... there's a reason why professional racers don't use it and still prefer to use race gas... E85 has a high RESEARCH octane, but a relatively low MOTOR octane... because North American gas stations advertise gas using an average of the two, aka "pump octane", the differences are hidden... MON ratings are more important than RON because a low or high MON is what will make a difference in causing preignition or not.... in comparison, race gas has high RON and MON, that's why it's still preferred in the motorsports world as it is truely dependable

[float_6969]

My standalone has knock sensing. It uses the stock knock sensor, so who knows. If anything, it seems to be overly sensitive and will often pull timing due to simple engine noise. It's possible the timing was severely retarded due to knock, but IIRC it has a limit to which it will retard the timing. That being said, I need to reiterate how little the engine was stressed. 5 psi on a T04E compressor on a 1.8L is a negligible amount of boost. Base timing was limited to 25° and no timing retard under boost. I could have been on 91 octane and not been near the knock limit of the fuel.

Not to say that I couldn't have still had pre-ignition. But as you've said, if I did, there wasn't much that could have been done about it.

[TheMAN]

knock detection is a big science... what you just said is the reason why many systems out there are not overly aggressive, because if they're too aggressive, their programming algorithms cannot differentiate between piston slap and detonation.... that's why stock systems can only do so much, that's why many built in systems in aftermarket EMS aren't that great... the problem is just simple... the people who made those systems didn't want to spend too much time developing/perfecting the system to not only be aggressive but still function past 4000-5000rpm.... I know for sure that many OEM systems out there ignore knock sensor readings past a certain RPM range, it is usually the mid range when mechanical noise becomes so loud that their simply wimpy systems couldn't pick out knock

knock sensors aren't the problem as they're simple piezo electric sensors tuned to a certain frequency range... although there's many different shapes and forms of knock sensors out there, they all work the same for the most part... the problem itself is the detection algorithms and the response algorithms associated with the system

from what I heard, it took years and years for John at J&S back in the develop his system out do Porsche's-- the benchmark of the 80s, to work at near full RPM range (from off idle to redline), individual cylinder detection and individual cylinder timing control... few systems today can match his based on my research.... many come close but not close enough

[mdb4879]

I don't know about preignition, but IF you were having detonation issues couldn't you have seen it in your EGTs? Or would having the sensor post-turbo nullify the spike you would normally see from the flame front escaping past the exhaust port?

Can the same type of spike in EGTs that are seen from detonation also be seen from preignition?

[dash]

E85 is not the magic pill to a fast car... there's a reason why professional racers don't use it and still prefer to use race gas

Take a good look around. There are no "professional racers" here..... and who wants to putt around in their regularly driven street car @5 psi, hooked on race gas?
E85 has been a magic pill for countless street driven monsters, reliably for years. No 'elaborate' knock systems either.
A few ca18s here as well, E85 and pump gas
From what I gather, Float has been fine with E85 on his combo for a long time.... so we focused more on any new variables

[float_6969]

This isn't the first time I've tuned an engine, ESPECIALLY this one. There was a reason I had it tuned rich, timing conservative, low boost, and a high octane fuel. I ran these pistons on an 8 port head with an SR T28 on 91 octane for a while. I FOUGHT detonation with that setup. During the summer months, it didn't matter how much I retarded the timing, it would still knock with load, and that was with only 7 psi of boost. Once I switched to E85, all of my knocking problems went away. I had it street tuned to 15psi with that setup for a while before I caught something in my air filter (it was behind the bumper) and tore a hole it it and ruined the compressor blades. I then went to the stock CA T25 because I had it laying around and ran that thing 15psi all the time. Intake temps could get pretty crazy with that little turbo cranked up that high, and I STILL never had any detonation.

Not that I'm claiming to be a magician, but I have an ear for detonation. I don't know why, but I hear it when others don't. I NEVER heard it on this motor since the rebuild. Not once.

I was thinking about it and came up with a few ideas. First off, why is the compression so low? Are the cams causing THAT MUCH reversion, that I'm loosing 50+psi of compression? Also, what if when they gapped the rings, they over-filed that cylinder. From the other work I've seen, this is a complete possibility. So if the compression has been low from the start in that cylinder, wouldn't the timing I was running to too retarded for that cylinder and drive the combustion temps up?

[TheMAN]

another thought... how does the other plugs look like? pics?

[boost_boy]

I'm spooked by the low compression on those domed high compression pistons. If you tuned your system to accommodate your engine's higher compression, does that tune now drive up your egts with the now considerably lower compression? I say, sort the compression issue, whether it be due to the camshafts or mechanical wear and then every thing else will fall into place.

[TheMAN]

I think high overlap will reduce compression

[mdb4879]

Overlap doesn't affect dynamic compression. Overlap takes place when the exhaust valves are closing and the intake valves are opening. Compression would increase at a specific rpm due to scavenging, but that wouldn't show up in a compression test. Changes in dynamic compression are caused by a change in when the intake valve close. Y'all are right in saying that his cams will decrease his compression, but it's not due to overlap.

Regardless, I don't believe his intake cam is that aggressive or his can timing was that far off to cause such a compression drop. IIRC, CA18DE pistons are 10:1 (Float has forged oversize copies so his CR should be a little higher), and his compression numbers are in the low stock range (8.5:1 and FSM spec is roughly 170-140psi).

My bet is that your (excessively) low compression is too large of a ring gap and that one cylinder is low because of the groove worn into the cylinder wall. I don't know that the low compression is the cause of your engine failure, but I believe this is the major culprit in your low compression numbers. Try removing your compression rings and measure the end gap just out of curiosity.

[float_6969]

another thought... how does the other plugs look like? pics?

The other 3 look fine, but I took some pics anyway.

[float_6969]

Overlap doesn't affect dynamic compression. Overlap takes place when the exhaust valves are closing and the intake valves are opening. Compression would increase at a specific rpm due to scavenging, but that wouldn't show up in a compression test. Changes in dynamic compression are caused by a change in when the intake valve close. Y'all are right in saying that his cams will decrease his compression, but it's not due to overlap.

Regardless, I don't believe his intake cam is that aggressive or his can timing was that far off to cause such a compression drop. IIRC, CA18DE pistons are 10:1 (Float has forged oversize copies so his CR should be a little higher), and his compression numbers are in the low stock range (8.5:1 and FSM spec is roughly 170-140psi).

My bet is that your (excessively) low compression is too large of a ring gap and that one cylinder is low because of the groove worn into the cylinder wall. I don't know that the low compression is the cause of your engine failure, but I believe this is the major culprit in your low compression numbers. Try removing your compression rings and measure the end gap just out of curiosity.

Should be a little over 10:1 compression, and on the last rebuild, was making about 210psi IIRC. This is how I discovered CA18DE pistons didn't have 9.5:1 compression like I thought, as this was too high for that kind of compression ratio.

The pistons are coming out this weekend so I can check the rings gaps.

I do have a bit of potentially good news. Apparently, when I bought these pistons waaaayyy back in the day, they were supposed to be 84mm. Apparently, something got screwed up somewhere, and they're only 83.5mm! This is actually good news for me because that means the block has enough room left in it to be bored out again. I am a little annoyed with the builder (again). I don't know for sure, but all of the bores are EXACTLY (like down to 0.0003") 83.5mm. Now maybe CP pistons are just that accurate that the bore works out to that size, but I thought you were supposed to take the diameter of the piston, add the piston to cylinder clearance value from the manufacturer, and then bore it out to that size. That is also the bore at room temperature, so I'm sure they're smaller when hot. I don't really have a way to check it though as I have no idea what the clearances are supposed to be. And maybe I'm off, and piston manufactures build the pistons to make boring easy.

[boost_boy]

Bootleg machine shop

[float_6969]

Yea, they're out of business now if that tells you anything...