Broken ring lands!!!!

[stony]

Here is a little story i was told /shown way back in the day>

 

Guy had a block sitting on the ground with a knock sensor hooked up so it was working. he had a big sledge hammer sitting next to the block. He said how hard do you think i need to hit this to get the knock meter to register. I figured maybe a small hammer and about the force you would use to hammer a nail.... WRONG didn't ever register. Then he picked up the sledge hammer and tapped it still nothing. He got to a point of almost swinging it like he was trying to ring the bell at the fair before it registered up to the damage range on the gage. Then he explained how when you get knock/detonation it's like hitting the top of the piston with the same amount of force every time it fires.

 

Knock/detonation sucks!!!!

[dr_hunt]

Splayed mains, h-beam rods, JE pistons, forged crank (although this will be a long process) and I will surely have someone tune this for me as I understand tuning and its concept just not patient enough... Thanks again

 

Sounds like my new motor.

[jack46]

Yes it is an LT1 and I have the factory tune with an FMU hahaaaa!! I know, I know I just wanted to get it on the road and now look where thats got me.. I am working on getting a short block right now so I can do the works to it.. Splayed mains, h-beam rods, JE pistons, forged crank (although this will be a long process) and I will surely have someone tune this for me as I understand tuning and its concept just not patient enough... Thanks again

 

 

We ALL want to 'get by' just pointing this out so next guy wil listenand maybe avoid some of the hasle...but he won't he will believe he wil be cautius and lucky

 

An LT1 rods and crank take ALOT. A friend has the stock rods, crank and has been making ~650 RWHP for a few yrs. He loses pistons not the crank. BTW that is stock 2 bolt he doesn't even use studs.

 

I use studs but stock rods and crank with 12 psi and no problems. DON'T forget new rod bolts. The stock rods MUST have new bolts then worth the risk as I said mine was in a Z his is in a 4500 lbs truck so it sees loads

[jasper]

Just some info on Knock sensors. The sledge hammer test is erroneous. What the knock sensor is "looking " for is a Noise of a certain frequency. It's not the impact. More like a tuning fork. Try that same test by tapping a wrench on the block and you'll see the timing retard. As far as detonation, EXTEMELY common in the marine industry. I used to review numerous complaints of defective pistons. DETONATION will deform/ crack ring lands. Also blow holes in pistons. The 2 frame fronts colliding is very destructive. Less ign. timing, high engine temps,low octane fuel, high boost pressure, highintake air temp, excessive engine load are just some of the culprits.

[dts300z]

We ALL want to 'get by' just pointing this out so next guy wil listenand maybe avoid some of the hasle...but he won't he will believe he wil be cautius and lucky

 

An LT1 rods and crank take ALOT. A friend has the stock rods, crank and has been making ~650 RWHP for a few yrs. He loses pistons not the crank. BTW that is stock 2 bolt he doesn't even use studs.

 

I use studs but stock rods and crank with 12 psi and no problems. DON'T forget new rod bolts. The stock rods MUST have new bolts then worth the risk as I said mine was in a Z his is in a 4500 lbs truck so it sees loads

 

I agree completely.. I think I might invest in some TRW dish pistons and some ARP rods bolts and see how it goes... Thanks guys

[grumpyvette]

BTW when you go to buy a ring compressor....this type works far better than the others

 

 

http://store.summitracing.com/partdetail.asp?autofilter=1&part=PRO%2D66766&N=700+115&autoview=sku

 

Proform 66766 $31

 

 

how they work is you clamp it around your piston and adjust it to that size before the rings are installed so the piston is a snug slide thru fit, then, install the rings, dip the rings and piston in clean oil, place the compressor over the cylinder on the block with the base firmly held against the block deck and push the piston into its much larger open enterance, as it slides thru the funnel like construction squeezes the rings into the grouves and they can,t spring back out untill they are in the bore, remember to line up the rod bolts and having them covered with the ends of a 3 ft long section or 3/8" fuel line to protect the crank journal is a good idea, having a ROD GUIDE TOOL you can use to guide and PULL THE PISTON INTO THE BORE WITH IS EVEN A BETTER IDEA

 

youll be surprised at how much easier they slide into the bore if you BOTH pull/guide and push the pistons into the cylinders rather than just beat them in with a hammer handle, it takes some practice but a few taps to get them moving with a fist, while pulling and guiding the rod into its journal is usually all that necessary with a well oiled piston and that type of ring compressor

[dts300z]

heck yea! thats great I usually use one of the pain in the butt ones that you gotta crank down on the piston. Ohhyea and I surely use the fuel line for the rod bolts. Thanks for the tip on that ring compressor I am actually going to be ordering all the parts in the next week or so. Thanks again that will be put on the list when I order everthing from summit.

[pparaska]

Grumpyvette - I use that exact compressor. I love it.

 

This is how I use it:

With the oil ring pack 1/8" above the deck of the block, install the tool over the piston and tighten the hose clamp to make it so that a lubed piston/ring set will be pretty snug with the piston - it'll get snug when it's the same size as the piston is below the oil ring pack.

 

After you get the oil ring pack in the cylinder, tighten the hose clamp again, making it compress the second ring and get snug with the ring land below the second ring. Tap until the second ring is in the cylinder. The reason for tightening the clamp again is that the land below the second ring is a smaller diameter than the piston is below the oil ring, and you want the second ring compressed to the same diameter as the land below the second ring so that the ring has no chance of sticking out beyond it and catching on the deck of the block.

 

Again, tighten the hose clamp on the compressor to compress the top ring more and get snug with the ring land under the top ring. Tap until the top ring is in. Same reason as above - the ring land below the top ring is a smaller diameter than the land below the second ring, so you need to tighten the compressor so that the top ring can't protrude outside of the top ring land.

 

I also use a plastic rod bolt guide. Its a long u shaped thing that fits over the rod bolts and guides them around the crank pin. Works great.

 

I'm betting that the tune cause excessive heat and the rings butted and jammed and ripped the lands loose.

[dts300z]

I have been bouncing back and forth about my build up and I might need a little smack in the face to get me back on track...

 

So hear is the plan but before I go into it this is just a for now setup on the short block. I should be running around 8-10 psi. I also picked up another LT1 (iron head) for $60 that I will use the short block for my forged setup.

 

1. 18.6 cc KB forged dish pistons (standard bore)http://store.summitracing.com/partdetail.asp?part=UEM%2DKB726%2D8&autoview=sku

2. stock rods and crank (ARP hardware for maincaps and rods and headbolts)

3. moly rings (top ring gap 0.026, 2nd ring gap 0.24)

4. new bearings (obviously)

5. CC306 http://store.summitracing.com/partdetail.asp?part=CCA%2D07%2D306%2D8&autoview=sku

6. already have CC 1.6 roller self aligning

7. CC hardened pushrods

8. already have springs and retainers

9. heads (I'm thinking of doing some mild porting)

10. felpro 1074 head gaskets

11. MSII EMS and EDIS 8 (no opti hooray) 60lb injectors

 

I'm looking to obtain around 550-600 rwhp and spin it around 6500+/-

 

Rearend gearing is going to be a 3.56 with a 26x11.5 et street

 

Please feel free to tear my thoughts apart!

[Nigel]

Just some info on Knock sensors. The sledge hammer test is erroneous. What the knock sensor is "looking " for is a Noise of a certain frequency.

 

6400Hz to be exact.

 

DETONATION will deform/ crack ring lands. Also blow holes in pistons. The 2 frame fronts colliding is very destructive.

 

I just read a great article on this very subject:

 

http://www.clubwrx.net/forums/tuning-electronic-engine-management/14426-engine-basics-detonation-pre-ignition.html

 

To summarize, detonation does crack ring lands, but it's Pre-Ignition that actually blows holes in pistons. Prolonged detonation can lead to, but is not necessary for pre-ignition. Pre-ignition is caused by hot spots that start the combustion process long before the spark plug even fires, which results in the piston trying to compress the expanding, burning (not exploding) mixture. Consequently, it is undetectable by a knock sensor.

 

Detonation is a spontaneous explosion of the mixture AFTER spark ignition has occurred usually at the point furthest from where ignition was started. It causes a rapid pressure spike (apparently NOT due to the flame fronts colliding) that resonates in the block at 6400Hz and can be detected by a knock sensor. The longer it takes the mixture to burn (the more advance required), the more likely detonation will occur. Consequently, combustion chamber designs that result in the shortest burn time (least advance required), are the least detonation prone. Interestingly, the coveted "HEMI" engine is apparently a poor design, requiring excessive advance making it prone to detonation...

 

Nigel

'73 240ZT

[Tony D]

Nigel makes a good point to watch: Preignition and Detonation are different things. You will never hear preignition. Things 'just break'...if you watch an engine with combustion pressure monitors in it on an O-Scope you can see the characteristic differences between detonation and preignition. The preignition trace will show the pressure spike WELL above the normal curve before the angle of TDC, whereas the detonation pressure spike will be far less severe, and occur AFTER the pressure has started rising from the point of normal spark ignition (and wellllll after TDC!).

 

Detonation can be endured for far longer, comparatively speaking, than preignition. People sometimes hear detonation, and will back out of it.

Preignition will occur silently and break things hard on the first or second occurance. The pressure spikes characteristic of preignition are of the order of metal-failure pressures, 10X more than the worst detonation episodes. Simply because of the difference in the timing---one occurs on a 'shrinking' space...the other on one that is 'expanding'... Detonation is simply fast flame travel causing that spike in pressure as the expanding gas simply raises pressures faster than the piston falling in the bore will allow. On a slow burning engine, the flame propogates and gas expands evenly. Add a fast flame front that overwhelms the volume, you hear that 'pinking' as the flame front raises to a pressure point resonant to your hearing. It can occur, yet never reach that point of audible notes. This prolonged detonation can break things, and mistakenly is sometimes attributed to 'preignition' as the damage appears the same on the surface.

 

Broken Plug Insulators, holes in pistons, melted piston crowns...people will argue each can be caused by either. They are both correct.

Preignition can do that on the first or second occurance.

Detonation will take prolonged ammounts of time to rack up that same damage toll.

[BRAAP]

Dan,

Any updates?

[dts300z]

not yet still trying to put together some casholine but hopefully soon. I will surely do a better job of documenting the build to share with you guys.