I think I broke a rod...
- Thread starter LinuxRacr
- Start date
The blocks are not the same the timing belt will tell you that it is shorter by just its length. The timing belt on the FP-DE is 2 teeth shorter than the FS-DE not much of a different but enough to make a difference. Also the rods are different too if you just changed the crank the compression ratio would be alot less since the pistons are the same. just changing the crank to a shorter stroke wiht the same rods would make the piston come alot farther away from the block deck at TDC than it does now the rods also had to be changed to achieve the shortened stroke. Alot of parts between the FP and SFS are interchangable the shortblock assembly however is not.
BioSehnsucht
Member
GAr... I haven't looked back at this thread in awhile. Been too distracted with multiple computer related and vehicle related issues (yay).. and pending snowboarding trip (YAY)
1st MP3 in NH: thank you for at least a benefit of the doubt (I think?)
LinuxRacr: I wasn't trying to attack you or anything, in fact I've met you once (at the Mazda6 gig down in Houston). We have a common friend... (ooh, I love suspense!)
...
Anyways, yes, that was aimed at Ben. I was quoting LinuxRacr to try and clarify why I was calling BS on Ben, but I supposed I should have added something along the lines of "since LinuxRacr said THIS..." to clarify that. Kinda shot myself in the foot with that attempted clarification..
And yes I haven't been a member here long, tho I've off and on (mostly off) read various protege boards for awhile, mainly because one of my best friends owns one.. I don't know as much about them as say I know about my car (240SX) and most that I know about the Protege I've picked up as third-hand knowledge..
Ben: True, higher gearing has higher resistance and is also why you can build boost faster in a higher gear. But just because you add some more resistance in higher gears, that doesn't mean you're not still putting a lot of stress on the engine. In fact, that resistance is really not that important.. 4th may be half the ratio of 2nd, but in the big grand scheme of things the drivetrain resistance doesn't make much difference - Now, if you were trying to accelerate instantly from a stop (clutch dump for example), it would require the engine to do more to reach/maintain the same amount of rotation, but we're accerlating while already moving, so we're adding small amounts of velocity, not huge instantaneous driver-debilitating clutch-destroying chunks of it.
MOST of the stress (nearly all of it) acting on the rod is from the compression it undergoes during the combustion stroke, from the cylinder pressures compressing the piston and rod down the crank, and as the crank turns the slight (altho still significant) sideloading of the piston (and therefore the rod) on the cylinder walls... it'll pick up stresses from the intake stroke as well (as the crank pulls the rod down and the suction of having to pull in air causes the rod to be pulled apart), along with the compression stroke (compression stress just like combustion stroke) as it forces all the air and gas to be REALLY FRIENDLY, and of course the exhaust stroke (pushing the exhaust out of the chamber).
Now, allmost all the stress is in that magical (hopefully well manged i.e. no detonation) explosion of the combustion stroke. If you bring in detonation, you now have (big) little extra jolts of force acting in places they shouldn't at times they shouldn't, pushing the piston (and therefore rod) in ways they're not supposed to. And if its REALLY BAD, like too far before TDC, it'll be like a head on collision between the detonation and the piston/rod assembly. Now imagine doing this say, 60-70 times a second. thats like taking a jackhammer to the rods (which unfortunately, being the monkey in the middle, and often weaker than the piston (in terms of how much abuse can be taken), must often be the component to deal with the bulk of these stresses). Maybe more like a jackhammer to a peice of iron on top the rods, but hey..
ANYWAYS.. point is: No matter WHAT GEAR, the higher the revs, the more the stress. Higher gears will increase stress, but by a far smaller (and nearly inconsequential, when vehicle already moving) degree than higher engine speed.
ALSO, just to make sure you got what my previous post was basicly saying: it WASN'T because he was WOT 2nd that killed the rod - it was merely that this particular time of WOT 2nd was all it took to break through what was left of the rod's structural integrity. Most of the damage was done while detonating under boost most likely, which makes for rediculous amounts of stress.
See, that's what I was saying
...
Now for the rods: Yes, the stock rods are probably good for more than stock, but not when detonating. chdesign mentioned Mazda rating the stock as good for 225whp (which means they can probably take more in a well tuned environment), but if you introduce prolonged detonation, you can break or permanently weaken (to the point of breaking, making it inevitable) things at much lower levels, and VERY FAST.
Also, keep in mind the FS motor has a rather craptastic rod ratio of ~1.47, IIRC. That doesn't help with detonation resistance at all, but does help with torque. For comparison, a SR20 for example is ~1.58, and FE3 is ~1.74. Higher is better (altho less torque, more resistance to detonation & etc and also better peak power due to better high end breathing (which is why its worse at low end - worse low end breathing)) .. ususally 1.9-2.2 for endurance motors. Here is a good page I've found that does a good job of covering rod ratios, for those inclined to find out more. It's a domestic site, but that doesn't really matter much, the underlying principles are the same (and smaller displacement motors can more effectively / safely use higher revs, than larger displacements).
Now if I could just figure out where I read formula/statistics for stresses under detonation vs boost.. I recall having read (site or a book, don't recall) something that illustrated how detonation is far more damaging than boost..
...
To those who bitched that or implied that I don't/can't know anything having been here for a short time... BAH!
I'll admit I've only had an interest in cars for a few years, but I have picked up much, and keep trying to pick up more. I will admit I'm not most familiar with the Protege engines but some things can be carried across all makes.
...
Now for that suspense: I arrived to the Mazda6 event in LinuxRacr's and myself's mutual friend's metallic silver-ish Protege (I don't recall the exact name, unfortunately). Some of you can probably guess who it would be, I hope LinuxRacr can
...
*puts on the Nomex underwear*
1st MP3 in NH said:
1st MP3 in NH: thank you for at least a benefit of the doubt (I think?)
LinuxRacr said:
LinuxRacr: I wasn't trying to attack you or anything, in fact I've met you once (at the Mazda6 gig down in Houston). We have a common friend... (ooh, I love suspense!)
...
Anyways, yes, that was aimed at Ben. I was quoting LinuxRacr to try and clarify why I was calling BS on Ben, but I supposed I should have added something along the lines of "since LinuxRacr said THIS..." to clarify that. Kinda shot myself in the foot with that attempted clarification..
And yes I haven't been a member here long, tho I've off and on (mostly off) read various protege boards for awhile, mainly because one of my best friends owns one.. I don't know as much about them as say I know about my car (240SX) and most that I know about the Protege I've picked up as third-hand knowledge..
big_ben said:
Ben: True, higher gearing has higher resistance and is also why you can build boost faster in a higher gear. But just because you add some more resistance in higher gears, that doesn't mean you're not still putting a lot of stress on the engine. In fact, that resistance is really not that important.. 4th may be half the ratio of 2nd, but in the big grand scheme of things the drivetrain resistance doesn't make much difference - Now, if you were trying to accelerate instantly from a stop (clutch dump for example), it would require the engine to do more to reach/maintain the same amount of rotation, but we're accerlating while already moving, so we're adding small amounts of velocity, not huge instantaneous driver-debilitating clutch-destroying chunks of it.
MOST of the stress (nearly all of it) acting on the rod is from the compression it undergoes during the combustion stroke, from the cylinder pressures compressing the piston and rod down the crank, and as the crank turns the slight (altho still significant) sideloading of the piston (and therefore the rod) on the cylinder walls... it'll pick up stresses from the intake stroke as well (as the crank pulls the rod down and the suction of having to pull in air causes the rod to be pulled apart), along with the compression stroke (compression stress just like combustion stroke) as it forces all the air and gas to be REALLY FRIENDLY, and of course the exhaust stroke (pushing the exhaust out of the chamber).
Now, allmost all the stress is in that magical (hopefully well manged i.e. no detonation) explosion of the combustion stroke. If you bring in detonation, you now have (big) little extra jolts of force acting in places they shouldn't at times they shouldn't, pushing the piston (and therefore rod) in ways they're not supposed to. And if its REALLY BAD, like too far before TDC, it'll be like a head on collision between the detonation and the piston/rod assembly. Now imagine doing this say, 60-70 times a second. thats like taking a jackhammer to the rods (which unfortunately, being the monkey in the middle, and often weaker than the piston (in terms of how much abuse can be taken), must often be the component to deal with the bulk of these stresses). Maybe more like a jackhammer to a peice of iron on top the rods, but hey..
ANYWAYS.. point is: No matter WHAT GEAR, the higher the revs, the more the stress. Higher gears will increase stress, but by a far smaller (and nearly inconsequential, when vehicle already moving) degree than higher engine speed.
ALSO, just to make sure you got what my previous post was basicly saying: it WASN'T because he was WOT 2nd that killed the rod - it was merely that this particular time of WOT 2nd was all it took to break through what was left of the rod's structural integrity. Most of the damage was done while detonating under boost most likely, which makes for rediculous amounts of stress.
Keith@FP said:
See, that's what I was saying
...
Now for the rods: Yes, the stock rods are probably good for more than stock, but not when detonating. chdesign mentioned Mazda rating the stock as good for 225whp (which means they can probably take more in a well tuned environment), but if you introduce prolonged detonation, you can break or permanently weaken (to the point of breaking, making it inevitable) things at much lower levels, and VERY FAST.
Also, keep in mind the FS motor has a rather craptastic rod ratio of ~1.47, IIRC. That doesn't help with detonation resistance at all, but does help with torque. For comparison, a SR20 for example is ~1.58, and FE3 is ~1.74. Higher is better (altho less torque, more resistance to detonation & etc and also better peak power due to better high end breathing (which is why its worse at low end - worse low end breathing)) .. ususally 1.9-2.2 for endurance motors. Here is a good page I've found that does a good job of covering rod ratios, for those inclined to find out more. It's a domestic site, but that doesn't really matter much, the underlying principles are the same (and smaller displacement motors can more effectively / safely use higher revs, than larger displacements).
Now if I could just figure out where I read formula/statistics for stresses under detonation vs boost.. I recall having read (site or a book, don't recall) something that illustrated how detonation is far more damaging than boost..
...
To those who bitched that or implied that I don't/can't know anything having been here for a short time... BAH!
I'll admit I've only had an interest in cars for a few years, but I have picked up much, and keep trying to pick up more. I will admit I'm not most familiar with the Protege engines but some things can be carried across all makes.
...
Now for that suspense: I arrived to the Mazda6 event in LinuxRacr's and myself's mutual friend's metallic silver-ish Protege (I don't recall the exact name, unfortunately). Some of you can probably guess who it would be, I hope LinuxRacr can
...
*puts on the Nomex underwear*
K
Keith@FP
Higher gears do put much more load on the engine, in a big part due to wind resistance. But you can break an engine in any gear if you try hard enough
Actually, the tensile loads on a rod are far greater than compressive loads. The nature of how power is created also means that if you double the amount of mixture in the combustion chamber (ie, 1 bar of boost), you only raise the peak cylinder pressure by about 20%. See Corky Bell's Maximum Boost for all the physics.
Of course, as has been said, it's the detonation that does the damage. I've pulled apart engines that had bent rods but still ran okay. They wouldn't have lasted much longer...
Now, those tensile loads? They increase exponentially with engine rpms. So try not to miss any shifts...
Keith
Actually, the tensile loads on a rod are far greater than compressive loads. The nature of how power is created also means that if you double the amount of mixture in the combustion chamber (ie, 1 bar of boost), you only raise the peak cylinder pressure by about 20%. See Corky Bell's Maximum Boost for all the physics.
Of course, as has been said, it's the detonation that does the damage. I've pulled apart engines that had bent rods but still ran okay. They wouldn't have lasted much longer...
Now, those tensile loads? They increase exponentially with engine rpms. So try not to miss any shifts...
Keith
BioSehnsucht
Member
Keith@FP said:Higher gears do put much more load on the engine, in a big part due to wind resistance. But you can break an engine in any gear if you try hard enough
Actually, the tensile loads on a rod are far greater than compressive loads. The nature of how power is created also means that if you double the amount of mixture in the combustion chamber (ie, 1 bar of boost), you only raise the peak cylinder pressure by about 20%. See Corky Bell's Maximum Boost for all the physics.
Of course, as has been said, it's the detonation that does the damage. I've pulled apart engines that had bent rods but still ran okay. They wouldn't have lasted much longer...
Now, those tensile loads? They increase exponentially with engine rpms. So try not to miss any shifts...
Keith
Ah yes, I stand corrected on tensile vs compressive. I only bothered searching for info on the rod length / stroke for the 3 engines to do a quick rod ratio calc in that little bit of my post. The rest was off the top of my head / from memory / re-inventing the wheel (so to speak) due to being to lazy to actually look it up. I actually wrote the post over a like 2 hour period at work between calls..
I remember now that you mention it the bit about cylinder pressure, I've read / own Maximum Boost but not recently and I certainly don't have it memorized
Thats of course why you can make lots of boost safely, as long as your fuel/air/spark is all good, and you don't go crazy on the CR and the chamber design isn't whack... but if any of that is not good enough you start detonating left and right and its bye byte motor... and at significantly lower PSI (possibly even none, depending on situation) than what you could do safely w/o detonation.I did mention RPM vs stress not being linear in my first post
And while I am no expert and have no right to say this, I still figure engine RPM is much more important to rod damage than gear ratio (within the realm of realistic situations).. of course the two combined is obviously no fun
Wow, I was right, hmmm, it must be because I know what the hell I'm talking about. Biowhatever, please don't try to teach me anything, because from what I've just read that you have posted are things that are pretty much obvious and don't take much thought to figure out yourself. You aren't telling me anything I didn't already know. I'm pretty sure why his rod broke. It was most likely from detonation because he is nowhere near the reported 225hp mark that the Mazda engineers speak of. And if you know Patrick personally like I do, you would know his driving habits. Nothing personal to Patrick, it's his car, he can drive it how he wants. I could give a s***. I wouldn't drive my car that hard that often though. But I say again, no offence intended. It's not my car.
BioSehnsucht said:GAr... I haven't looked back at this thread in awhile. Been too distracted with multiple computer related and vehicle related issues (yay).. and pending snowboarding trip (YAY)
1st MP3 in NH: thank you for at least a benefit of the doubt (I think?)
LinuxRacr: I wasn't trying to attack you or anything, in fact I've met you once (at the Mazda6 gig down in Houston). We have a common friend... (ooh, I love suspense!)
...
Anyways, yes, that was aimed at Ben. I was quoting LinuxRacr to try and clarify why I was calling BS on Ben, but I supposed I should have added something along the lines of "since LinuxRacr said THIS..." to clarify that. Kinda shot myself in the foot with that attempted clarification..
And yes I haven't been a member here long, tho I've off and on (mostly off) read various protege boards for awhile, mainly because one of my best friends owns one.. I don't know as much about them as say I know about my car (240SX) and most that I know about the Protege I've picked up as third-hand knowledge..
Ben: True, higher gearing has higher resistance and is also why you can build boost faster in a higher gear. But just because you add some more resistance in higher gears, that doesn't mean you're not still putting a lot of stress on the engine. In fact, that resistance is really not that important.. 4th may be half the ratio of 2nd, but in the big grand scheme of things the drivetrain resistance doesn't make much difference - Now, if you were trying to accelerate instantly from a stop (clutch dump for example), it would require the engine to do more to reach/maintain the same amount of rotation, but we're accerlating while already moving, so we're adding small amounts of velocity, not huge instantaneous driver-debilitating clutch-destroying chunks of it.
MOST of the stress (nearly all of it) acting on the rod is from the compression it undergoes during the combustion stroke, from the cylinder pressures compressing the piston and rod down the crank, and as the crank turns the slight (altho still significant) sideloading of the piston (and therefore the rod) on the cylinder walls... it'll pick up stresses from the intake stroke as well (as the crank pulls the rod down and the suction of having to pull in air causes the rod to be pulled apart), along with the compression stroke (compression stress just like combustion stroke) as it forces all the air and gas to be REALLY FRIENDLY, and of course the exhaust stroke (pushing the exhaust out of the chamber).
Now, allmost all the stress is in that magical (hopefully well manged i.e. no detonation) explosion of the combustion stroke. If you bring in detonation, you now have (big) little extra jolts of force acting in places they shouldn't at times they shouldn't, pushing the piston (and therefore rod) in ways they're not supposed to. And if its REALLY BAD, like too far before TDC, it'll be like a head on collision between the detonation and the piston/rod assembly. Now imagine doing this say, 60-70 times a second. thats like taking a jackhammer to the rods (which unfortunately, being the monkey in the middle, and often weaker than the piston (in terms of how much abuse can be taken), must often be the component to deal with the bulk of these stresses). Maybe more like a jackhammer to a peice of iron on top the rods, but hey..
ANYWAYS.. point is: No matter WHAT GEAR, the higher the revs, the more the stress. Higher gears will increase stress, but by a far smaller (and nearly inconsequential, when vehicle already moving) degree than higher engine speed.
ALSO, just to make sure you got what my previous post was basicly saying: it WASN'T because he was WOT 2nd that killed the rod - it was merely that this particular time of WOT 2nd was all it took to break through what was left of the rod's structural integrity. Most of the damage was done while detonating under boost most likely, which makes for rediculous amounts of stress.
See, that's what I was saying
...
Now for the rods: Yes, the stock rods are probably good for more than stock, but not when detonating. chdesign mentioned Mazda rating the stock as good for 225whp (which means they can probably take more in a well tuned environment), but if you introduce prolonged detonation, you can break or permanently weaken (to the point of breaking, making it inevitable) things at much lower levels, and VERY FAST.
Also, keep in mind the FS motor has a rather craptastic rod ratio of ~1.47, IIRC. That doesn't help with detonation resistance at all, but does help with torque. For comparison, a SR20 for example is ~1.58, and FE3 is ~1.74. Higher is better (altho less torque, more resistance to detonation & etc and also better peak power due to better high end breathing (which is why its worse at low end - worse low end breathing)) .. ususally 1.9-2.2 for endurance motors. Here is a good page I've found that does a good job of covering rod ratios, for those inclined to find out more. It's a domestic site, but that doesn't really matter much, the underlying principles are the same (and smaller displacement motors can more effectively / safely use higher revs, than larger displacements).
Now if I could just figure out where I read formula/statistics for stresses under detonation vs boost.. I recall having read (site or a book, don't recall) something that illustrated how detonation is far more damaging than boost..
...
To those who bitched that or implied that I don't/can't know anything having been here for a short time... BAH!
I'll admit I've only had an interest in cars for a few years, but I have picked up much, and keep trying to pick up more. I will admit I'm not most familiar with the Protege engines but some things can be carried across all makes.
...
Now for that suspense: I arrived to the Mazda6 event in LinuxRacr's and myself's mutual friend's metallic silver-ish Protege (I don't recall the exact name, unfortunately). Some of you can probably guess who it would be, I hope LinuxRacr can
...
*puts on the Nomex underwear*
:wtf: i don't know whether to give him props on his knowledge of cars or to tell him to get a life for writing that much.
tough choice.
I live in Davis but all my tools are at my parents house in Fair Oaks so I go home to do car work almost every weekend. Ranch Cordova is only a 10 min drive from my house. I bought my coolant tank there when I drove over my last one. I'm just surprised that there aren't more car recycling places than the ones mentioned. In rancho there are about 500 car recycling places.
BioSehnsucht
Member
big_ben said:
Hey, it was YOU who said that what he was doing shouldn't be any cause for anything to break (sure, if he never detonated before), but really, it was putting quite a bit of stress on the engine...
And no, I don't know him well, I've only talked to him once really, but have heard much of his exploits and misfortunes through our mutual friend, and also have read some of his threads on the various boards ...
LinuxRacr said:
Now I know why he's (our friend) addicted to it.Did you ever drain that foglight fluid?
I swear those mp3's need foglight rock shields
Hey Linux for a block since you have the head still remember the Probe, MX-6 and 626 all shared our blocks and if you are getting all that forged goodness the interneals of it don't really matter.....call the boys up at www.mazmart.com and see what they can do also check out www.car-part.com they have a load of mazda 2.0L blocks listed. Hope you get it back together soon man I'm about to send my header, turbing housing and downpipe to the coater once i get them back from teh welder who is taking forever to get it all TIGed up. Well anyways if I can help you in anyway let me know.....oh yeah and bio nice comment on the rod ratio that does come into play which is why i'm glad I have a FP-DE with a near perfect rod ratio for performance driving.....can't remember it now for some reason though lol
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