Engine Carnage

[myshtern]

2 of the rods are fuxored. The piston with the broken rod also has a broken skirt. The other pistons are in pretty good shape except for that one with a scratched side skirt.

The rod that broke caused some carnage inside of the block. It made 2 opposing holes in the block and ravaged the inside destroying the girdle and cylinder walls. the bent rod just notched the block a little bit.

http://xs72.xs.to/pics/06115/rods2.jpg
http://xs72.xs.to/pics/06115/rods1.jpg

[Terry]

how the hell did you do that?

[myshtern]

15 pounds of boost.

[M@]

15psi? That's all? What motor?

[myshtern]

D16Z6

[Weston-work]

Wow, those rods are made out of like hotdog-material...

[STIBungy]

Those rods reminded me of these:

http://www.tacojohns.com/Graphics/Food/Desserts/Medium/Churro.gif

Yummy!

[myshtern]

My pinky finger from the side

http://xs72.xs.to/pics/06116/rod-pinky.jpg

[JL LGT]

Nice work!

Time for some more fun to begin.... with the re/build!

[myshtern]

Well I inspected the ring landings very closely today and I noticed a tiny crack on the piston with the straight rod. Then I looked at piston with the bent rod and noticed a crack in the EXACT same place. The piston with the broken rod had no such crack. So then I went to look at the 4th piston and it had a crack in the exact same place again. I poked at the crack and the ring landing just came out.

Defintely looks like a structural weak point in the honda pistons.

[rmcdaniels]

OEM Honda piston ring lands are notoriously brittle. It doesn't take much to break them.

[doctorstupid]

http://mattmasonms.com/hosted/vr-4rod1.jpg

:D

[myshtern]

OEM Honda piston ring lands are notoriously brittle. It doesn't take much to break them.
I'm just surprised that they all cracked in the exact same place.
Someone on another forum said they crack on the intake valve side.

[exciv2000]

LOL PWNT

[M@]

Bahahahaha! Nice pic, Dr.

[doctorstupid]

Bahahahaha! Nice pic, Dr.
I damn near died of laughter when I took that oil pan down.

[Mario]

So Alex, did you seriously not believe me when I told you FI will bring you troubles?

Experience > interweb reading.

[Skaterkid]

Annndd? What did you expect when you pushed a D Series towards 15 lbs? The best tune in the world does not make up for a weak engine. And when you find the limits of an engine you will find the weak points. I'm not surprised they cracked in the same place. There's some sort of stress concentrator at that point that causes it to fail.

[Mario]

Ok guys, just a slight defense here...

15psi on a 14b is not a lot. It's not like he was running a 1AR T3/T4 at 15psi...

[myshtern]

So Alex, did you seriously not believe me when I told you FI will bring you troubles?

Experience > interweb reading.
:rolleyes: Mario, had I not cranked it up this setup would have lasted as long as I wanted it to. As I recall, you couldnt even get your 5 million dollar setup to boost 7psi because you used your stock catalytic converter. You should have done more interweb reading.

The whole tune talk came from Weston who said my car was untuned when in fact it was tuned quite nicely. I know that d-series rods are twigs, everyone knows that. You guys really think I didnt expect this?

Fast cars arent reliable cars, I think we've established that.

[Mario]

:rolleyes: Mario, had I not cranked it up this setup would have lasted as long as I wanted it to. As I recall, you couldnt even get your 5 million dollar setup to boost 7psi because you used your stock catalytic converter. You should have done more interweb reading.

The whole tune talk came from Weston who said my car was untuned when in fact it was tuned quite nicely. I know that d-series rods are twigs, everyone knows that. You guys really think I didnt expect this?

Fast cars arent reliable cars, I think we've established that.

My 5 million dollar setup was actually about $1500, and it boosted 7psi beautifully. *shrugs*

[myshtern]

Ok guys, just a slight defense here...

15psi on a 14b is not a lot. It's not like he was running a 1AR T3/T4 at 15psi...
Actually I have a td04-13g which is considerably smaller than a 14B. However, you are wrong because it wasnt 15psi at the turbo outlet, it was 15psi at the map sensor. It wouldnt flow as much, but the boost pressure is still the same. I dont think my IATs were very high.

[Mario]

No, I am not wrong. It's plain fact. A 14b turbo will produce a lot less engine HP than a T3/T4 at xx amount PSI with similar setups and conditions. You can't argue that.

[myshtern]

No, I am not wrong. It's plain fact. A 14b turbo will produce a lot less engine HP than a T3/T4 at xx amount PSI with similar setups and conditions. You can't argue that.
Thats not what I'm arguing. I'm saying at the throttle body, 15psi is 15psi. The only difference can be in the IATs. One wont be effficient at 15psi and the other will. Thats why I said at 15psi, I dont think my IATs were very high.

[Weston-work]

The whole tune talk came from Weston who said my car was untuned when in fact it was tuned quite nicely.

You already admitted that you were boosting higher than your MAP sensor is capable of reading, so I'm having some trouble seeing how it could be tuned "quite nicely", especially since shortly before it blew, you had indicated that it had not even seen a dyno yet.

[myshtern]

You already admitted that you were boosting higher than your MAP sensor is capable of reading, so I'm having some trouble seeing how it could be tuned "quite nicely", especially since shortly before it blew, you had indicated that it had not even seen a dyno yet.
The fact that it didnt blow because of detonation or melting pistons shows that it was tuned nicely.

[Weston-work]

The fact that it didnt blow because of detonation or melting pistons shows that it was tuned nicely.

That's almost sig worthy. So, you're saying that tuning has no effect on the stress that the connecting rods see? :rofl: Don't get me wrong... we all know that D-series motors aren't real strong, but I'm saying that crappy tuning can certainly contribute to this kind of failure. How can you even say that spark advance doesn't have an effect on the stress on the rods? The more your ignition timing is advanced, the more combustion that takes place on the compression stroke. Too much advance and it fights the piston as it is trying to come up, and guess what gets stressed in that situation... the connecting rods! This is why you lose power when you advance the ignition timing passed the optimal point, even though you may not hear detonation yet. I did the typical thing of advancing the timing until it detonates, then backing off half a degree or so, but when I went to the dyno, I found more power in backing it off a little more.

[servion]

The cylinder pressures were definitely a bit high to cause all that trouble for you though... were you running 15psi absolute or gauge pressure? What EMS, and what was the boost at the map sensor? Jeff Evans has tuned a bone-stock d16z6 with nothing but headstuds to over 300whp and had it hold without a problem (at 17psi).... the trick to making a stock motor last is making sure that the peak cylinder pressures occur before MBT.

Regardless, sorry to see it go, but at least the d16's are a dime a dozen! :) Good luck getting her back together.

[-=[Juztin]=-]

you can't talk about being tuned nicely when youve got a couple holes in your block n00b :)

[myshtern]

That's almost sig worthy. So, you're saying that tuning has no effect on the stress that the connecting rods see? :rofl: Don't get me wrong... we all know that D-series motors aren't real strong, but I'm saying that crappy tuning can certainly contribute to this kind of failure. How can you even say that spark advance doesn't have an effect on the stress on the rods? The more your ignition timing is advanced, the more combustion that takes place on the compression stroke. Too much advance and it fights the piston as it is trying to come up, and guess what gets stressed in that situation... the connecting rods! This is why you lose power when you advance the ignition timing passed the optimal point, even though you may not hear detonation yet. I did the typical thing of advancing the timing until it detonates, then backing off half a degree or so, but when I went to the dyno, I found more power in backing it off a little more.
Weston, I agree with everything you are saying but for the love of god just stop saying my car was untuned. Yes for the last 3 psi the boost retard stopped and the mixture was lean but its obvious that thats not what caused this to happen. The rods are twigs, smaller than my pinky finger. Sure it may have slightly contributed by adding to that stress. But sooner or later they would have gone. Trial and error - enough people have blown these engines to show that it was just simply too much stress on the tiny rods even with hours and hours of dyno tuning.

Servion, the autometer gauge was showing 15psi, so thats what I'm going off of. That means the absolute pressure was slightly below that, right? D16s are a dime a dozen, I already have a replacement. I just need to swap heads and the wiring harness now and I'll be ready to stick back in. Best part is, the whole replacement is costing me about the same as an hour of dyno tuning plus I've got ARP head studs now and I'm having 10x more fun and learning a little about these engines.

[doctorstupid]

9 times out of 10, a crack in the top ring land is the result of detonation. And at 15PSIg, absolute pressure was more like 27PSIa up here. It all suggests a poor tune, but as you said, it's a cheap fix, and you're learning, so fuck it; blowing shit up is half the fun. Don't get stuck insisting it was a good tune, refusing to adapt to what killed it, and blow the next one because you're too proud of your tune to change it. Or else you'll end up with shit like this :D

http://twinturbo.us/piston.jpg

[HONDA GHANDI]

Now that is a dead piston. Nice work.

[doctorstupid]

I've got all sorts of fun broken shit around here :D

http://www.mattmasonms.com/img/FUBAR/crank.jpg

[Skaterkid]

You're incorrect Alex, 15 psi from a larger turbo is more stressful because there will be more oxygen molecules per lb, per unit of volume, whatever you want to define. That added density causes a much higher cylinder pressure which is what will bend or throw rods.

[myshtern]

You're incorrect Alex, 15 psi from a larger turbo is more stressful because there will be more oxygen molecules per lb, per unit of volume, whatever you want to define. That added density causes a much higher cylinder pressure which is what will bend or throw rods.
I agree, but doesnt that come from lower temperatures?
I'm sure you know more physics than I do so explain if I'm wrong.

[doctorstupid]

You're incorrect Alex, 15 psi from a larger turbo is more stressful because there will be more oxygen molecules per lb, per unit of volume, whatever you want to define. That added density causes a much higher cylinder pressure which is what will bend or throw rods.
Nice sweeping generalization there.

[David]

sweet jesus, how do you snap a crank shaft?

[Skaterkid]

No, look at the flow rates. Higher flow at the same pressure means more oxygen. Not just from lower temps.

[doctorstupid]

No, look at the flow rates. Higher flow at the same pressure means more oxygen. Not just from lower temps.
Yes, but a higher rated flow doesn't mean that's what the engine is intaking. The volume flow on the compressor map is the condition at the compressor inlet, airflow at the outlet is determined by engine size, speed, and volumetric effeciency; your engine can only intake it's own displacement every 2 revolutions, minus effeciency losses. Put a 1,000CFM turbo on an engine intaking 200CFM, and you're only moving 200CFM through the throttle body, at a 1.0 pressure ratio or 4.0. The difference is at at a 4.0 PR you're intaking 800 CFM through the compressor inlet; still not using the whole map.

Just because I can see Kentucky on a map of the US doesn't mean I'm actually in Kentucky ;)

[Skaterkid]

Yeah, I had a brain fart on that post. However, by having a turbo with a larger A/R one would see lower backpressure helping feed more oxygen into the combustion chamber, by having less exhaust gas remaining in the combustion chamber. That will help you flow more air into the engine since you will have a better VE. On the flip side that larger turbo will keep detonation at bay by keeping temps lower in the cylinder.

[doctorstupid]

Yeah, I had a brain fart on that post. However, by having a turbo with a larger A/R one would see lower backpressure helping feed more oxygen into the combustion chamber, by having less exhaust gas remaining in the combustion chamber. That will help you flow more air into the engine since you will have a better VE. On the flip side that larger turbo will keep detonation at bay by keeping temps lower in the cylinder.
So back to the sweeping generalization, that's assuming a hell of a lot about operating conditions.

[doctorstupid]

sweet jesus, how do you snap a crank shaft?
Honda engineering at its finest.

That was a stock 89 prelude S, B20A1 or something with a whopping 90 horsepower or so, at 140k miles. Just went and snapped one day, sending me into a fit of laughter when I removed it.

[HONDA GHANDI]

Honda engineering at its finest.

That was a stock 89 prelude S, B20A1 or something with a whopping 90 horsepower or so, at 140k miles. Just went and snapped one day, sending me into a fit of laughter when I removed it.


Nice. One of the very few Honda cranks that will break for no reason. Along with the D series cranks.

[Weston-work]

sweet jesus, how do you snap a crank shaft?

That's what happens when doctorstupid brings his DSM curse to Hondas. ;)

[KennyKen]

Well, you know what they say...if you're not breaking anything then you're not making enough power ;) :D

[doctorstupid]

That's what happens when doctorstupid brings his DSM curse to Hondas. ;)
Nice try, I got that little gem before I even owned a DSM ;)

[doctorstupid]

Nice. One of the very few Honda cranks that will break for no reason. Along with the D series cranks.
It broke at a logical point, right next to a journal, and it's understandable that it be a weak crank since the engine isn't even putting down three digits, it just cracks me up it couldn't take all 90hp of fury :rofl: