Zoom zoom BoOm x2.

[BlkZoomZoom]

page 11. You must have missed them.

 

[TurfBurn]

yeah just found that... LOL... I"m looking.

 

[igdrasil]

I dont know but those shattered parts looks melted. There are signs of hot spots, preignition and detonation.

 

[BlkZoomZoom]

I dont know but those shattered parts looks melted. There are signs of hot spots, preignition and detonation.

I agree. But when you expose pieces like that they do create hot spots.

 

[igdrasil]

I agree. But when you expose pieces like that they do create hot spots.

which pieces? There can be no pieces of piston if they didnt hit anything, those pieces does not come appart with speed. The valve train is ok, no valves were smashed.

I think we all agree that one of the pistons is completely fried, right? The others where going the same route. When they start to fry like that, the first thing that will most likely come appart is where the valve groove clearance is...no?

 

[BradC]

But if the clearences were not tight enough, and the rings snapped the lands, then all of the fragments were hot spots...which could have made it look like detonation...

 

[TurfBurn]

I see that every one of the fractures occured right on the stress riser at the back of the valve relief...

I don't think it was a clearance issue that was heat related... the skirt is MUCH wider than the rings.. while the ring landing see more heat etc I would expect to see the landing between first and second ring to crack moreso than the top valve edge... Two of the cylinders show a clean brittle fracture, one cylinder shows a brittle/ductile mixed fracture, and cylinder one appears to be a rather ductile fracture which would indicate a heat stress for it... or the heat after the fact melted it enough to give the appearance of a ductile fracture...

I don't think the ring flutter can do that, and you would have had more running issues at that point... so I doubt that would have been THAT severe.. however what were you running for ring gap? 20+ thousandths or not? I'm wondering if the rings butted and then at the high rpm seized against the wall and the piston basically slammed down against the ring and snapped off those reliefs at the weakest point at the top of the piston... that would be my leading candidate... I'm just trying to think about the rotation of the motor and which direction the inertia would have been snapping the piston as it pulled down.

 

[BlkZoomZoom]

The rings cam with 14 thous. gap, I increased it to 19 thous.

 

[TurfBurn]

I'm running around 22 I believe.

 

[igdrasil]

You will need to pull the pistons out to see if there was a clearance issue

 

[ddogg777]

I don't think it was a clearance issue that was heat related... the skirt is MUCH wider than the rings..

What do you mean here Steve? Wider in diameter, thicker, or...
no comprendo.

 

[TurfBurn]

Diameter... the skirts aren't very thick... but the widest (diameter) part of the piston is the skirt... that is the true bore size (and how you measure a piston when it is out of the motor). The top is tapered to allow for additional expansion...

 

[anarchistchiken]

Those numbers don't work, unless you were spraying nitrous.


Torque=HP x 5252/RPM

In your case
262 x 5252/3300 = 416.97 lb/ft torque.

There is no way you could make that kind of torque on a t25 without nitrous.

Crack is bad, mmk?

According to this formula, a Civic making 150 hp at 4000 rpms is making 196 lb-ft? In a honda motor? at 4000 RPMs? bulls***!

This forumla is ******* idiotic and you should be banned for even thinking about posting it here.

 

[TurfBurn]

Crack is bad, mmk?

According to this formula, a Civic making 150 hp at 4000 rpms is making 196 lb-ft? In a honda motor? at 4000 RPMs? bulls***!

This forumla is ******* idiotic and you should be banned for even thinking about posting it here.

You are making a fool of yourself with those comments.. that IS the mathematical formula of the relationship between torque and horsepower... plain and simple... it's just the straight up math.

If a honda was making 150 horse at 4000 then it would have that torque... no way around it...

 

[MPNick]

Diameter... the skirts aren't very thick... but the widest (diameter) part of the piston is the skirt... that is the true bore size (and how you measure a piston when it is out of the motor). The top is tapered to allow for additional expansion...

The skirts are taperd and sometimes also barrel ground. The head of the piston, just above and below the ring pack area is round. It is up to .050 smaller then the skirts. Because of the heat at the top of the piston they need to be smaller.

 

[jurgs01]

Crack is bad, mmk?

According to this formula, a Civic making 150 hp at 4000 rpms is making 196 lb-ft? In a honda motor? at 4000 RPMs? bulls***!

This forumla is ******* idiotic and you should be banned for even thinking about posting it here.

Study before you post if you don't know.

http://www.acs.ucalgary.ca/~csimpson/Tech/Calculations.html

 

[MPNick]

I dont know but those shattered parts looks melted. There are signs of hot spots, preignition and detonation.

100%, thats why they failed. Now the questions is why did it detonate? Need to see the tune map.

 

[MPNick]

Well sure, it wouldn't bind everywhere, just in one spot. Especially if the clearance was too much, the piston would be against the wall on one side (impossible to bind since the ring would be seated furthest in the groove here) and the extra looseness on the other wall would cause the ring to fail and bind, thus breaking the lip in that area... (rockon)
...

(huh)

How is this the case?

 

[MPNick]

The rings probably got toasted when the engine over-revved. Our longer stroke means very high speed piston movement. They then could have destroyed the pistons...What piston/cylinder clearance were you running and what rings did you have?

How does a ring "toast" with out stroke?

 

[anarchistchiken]

Yeah, formulas are fun. Unfortunatly, they're all based on absolute constants and ideal conditions, so they're usually not dead on.

Turfburn, I will take your word for it because you know a heluvalot more about this stuff than I do. It doesn't make any sense though. I mean if a v-8 and an I-4 both make 100 hp at 3000 rpms, they would both have the same torque output? I just dont get it. If it's that absolute, then why is there a difference in the torque between a root's type and a centrifigul supercharger at the same hp?