Spun bearing? Replace pitted pistons?
#1
Spun bearing? Replace pitted pistons?
So,
Before going FI, I rebuilt the motor ~8 months ago (new rings, bearings, honed and decked the block), but left in the "slightly" pitted pistons in.
Two days ago I overboosted and hit 15psi during a tuning run, the motor developed a clunking noise right after. I pulled the plugs and the pistons and con rods appear intact. However, the pistons are really pitted (I can see that w/ my endoscope.)
I'm running 12psi, should I take the time to pull the pistons and replace them? If so, the rings have only a few thousand miles on them, can I reuse them?
I don't know what the clunking is, spun bearing? Who knows??
Before going FI, I rebuilt the motor ~8 months ago (new rings, bearings, honed and decked the block), but left in the "slightly" pitted pistons in.
Two days ago I overboosted and hit 15psi during a tuning run, the motor developed a clunking noise right after. I pulled the plugs and the pistons and con rods appear intact. However, the pistons are really pitted (I can see that w/ my endoscope.)
I'm running 12psi, should I take the time to pull the pistons and replace them? If so, the rings have only a few thousand miles on them, can I reuse them?
I don't know what the clunking is, spun bearing? Who knows??
#2
Former Vendor
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Depends on your goals. Do you want pictures of a catastrophic explosion and a $750-2000 replacement bill? Keep on driving it. Do you want to deal with the issue and make the car reliable again? Rebuild it.
#4
I don't understand what the issue is...if the motor developed an internal noise after overboosting it...it is obvious that you are going to have to pull it apart and fix the damaged components. Are you going to wait for the whole thing to grenade and then have to spend money on an engine core?
It's a no-brainer.
It's a no-brainer.
#5
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If you got the extra cash, forged internals, you won't regret it. I promise lol.
Definately rebuild it, I was in your shoes, some what, 2 weeks ago. Its worth it in the end. I'm saying this and Im not even into boost yet hah.
Definately rebuild it, I was in your shoes, some what, 2 weeks ago. Its worth it in the end. I'm saying this and Im not even into boost yet hah.
#7
I don't understand what the issue is...if the motor developed an internal noise after overboosting it...it is obvious that you are going to have to pull it apart and fix the damaged components. Are you going to wait for the whole thing to grenade and then have to spend money on an engine core?
It's a no-brainer.
It's a no-brainer.
What I don't know is: do pitted pistons warrant a rebuild? Assuming the noise isn't from the bottom end.
#9
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How did you achieve 15psi under a "light load?" Are you suffering from flow restrictions or just understating how you blew it up?
Your engine could certainly run with a bent rod, it just might not run well and it might make abnormal noises while doing so.
BTW - Pitted piston tops will create hot spots and combined with FI is a recipe for acute depression. Out of concern for your mental health I would recommend that you change them.
Your engine could certainly run with a bent rod, it just might not run well and it might make abnormal noises while doing so.
BTW - Pitted piston tops will create hot spots and combined with FI is a recipe for acute depression. Out of concern for your mental health I would recommend that you change them.
#10
How did you achieve 15psi under a "light load?" Are you suffering from flow restrictions or just understating how you blew it up?
Your engine could certainly run with a bent rod, it just might not run well and it might make abnormal noises while doing so.
BTW - Pitted piston tops will create hot spots and combined with FI is a recipe for acute depression. Out of concern for your mental health I would recommend that you change them.
Your engine could certainly run with a bent rod, it just might not run well and it might make abnormal noises while doing so.
BTW - Pitted piston tops will create hot spots and combined with FI is a recipe for acute depression. Out of concern for your mental health I would recommend that you change them.
Ok, so the advice so far is to replace the pistons and rods. I guess, based on what I've read, that I'll go ETD rods and possibly OEM pistons.
I've heard of people reusing rings if they're still pretty new. Is this a **** idea?
#11
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I had a bottle of wine a few nights ago and on the drive home it was cold out and the car felt insano fast but kept popping and bucking...because I was overboosting to 19psi/230kpa. lol.
Oh well, just pull over and twist the boost controller and smile because I spent the money wisely on a built motor with overboost protection. If I had a stock motor I would have blown it up 3-times by now. So you have an idea of the amount of headroom I have with 8.6:1 pistons, on a dynodynamics I've had 252wtq/4000rpm/15psi with 30* of advance with no detonation. Buy the low-comp pistons because its $400 well spent.
#13
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You want them to mate to the cylinder walls to achieve a good seal. When you take them out and put them back in, it will be impossible to keep them in the exact orientation that they were already in and mated. Replace the rings and check the tolerances well to make sure you don't need an overbore. Be sure to re hone either way.
#14
My "target boost" is 15psi.
I had a bottle of wine a few nights ago and on the drive home it was cold out and the car felt insano fast but kept popping and bucking...because I was overboosting to 19psi/230kpa. lol.
Oh well, just pull over and twist the boost controller and smile because I spent the money wisely on a built motor with overboost protection. If I had a stock motor I would have blown it up 3-times by now. So you have an idea of the amount of headroom I have with 8.6:1 pistons, on a dynodynamics I've had 252wtq/4000rpm/15psi with 30* of advance with no detonation. Buy the low-comp pistons because its $400 well spent.
I had a bottle of wine a few nights ago and on the drive home it was cold out and the car felt insano fast but kept popping and bucking...because I was overboosting to 19psi/230kpa. lol.
Oh well, just pull over and twist the boost controller and smile because I spent the money wisely on a built motor with overboost protection. If I had a stock motor I would have blown it up 3-times by now. So you have an idea of the amount of headroom I have with 8.6:1 pistons, on a dynodynamics I've had 252wtq/4000rpm/15psi with 30* of advance with no detonation. Buy the low-comp pistons because its $400 well spent.
Hustler, did you notice a significant loss of power when off boost w/ 8.6:1? Would you recommend 8.6 over 9:1?
Thanks.
#15
You want them to mate to the cylinder walls to achieve a good seal. When you take them out and put them back in, it will be impossible to keep them in the exact orientation that they were already in and mated. Replace the rings and check the tolerances well to make sure you don't need an overbore. Be sure to re hone either way.
Thanks.
#16
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Read through my dyno thread and you'll probably agree too. I have lots and lots of headroom.
if you're really worried about losing power off boost, then go with bigger pistons.
#17
I came from a seriously tired 1.6 so no, it felt significantly stronger than my 1.6. You can advance spark MUCH further with lowered compression and I bet you can up the octane and get close to the stock off-boost output. FM seems to churn out tons and tons of 9.0:1 compression motors that make crazy power, but I think I'm making more torque/psi, especially when you compare dyno measurement differences.
Read through my dyno thread and you'll probably agree too. I have lots and lots of headroom.
if you're really worried about losing power off boost, then go with bigger pistons.
Read through my dyno thread and you'll probably agree too. I have lots and lots of headroom.
if you're really worried about losing power off boost, then go with bigger pistons.
#19
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Hustler isn't the only one that understands that lower dynamic compression will allow you to run more boost and more timing and ultimately make significantly more power on pump gas. It is just a little science and math that happens to be indisputable. What you choose to do with this information is up to you. I wish there were more true believers like him on this forum. I guess it will take time for more to choose this route. You won't be disappointed.
#20
Hustler isn't the only one that understands that lower dynamic compression will allow you to run more boost and more timing and ultimately make significantly more power on pump gas. It is just a little science and math that happens to be indisputable. What you choose to do with this information is up to you. I wish there were more true believers like him on this forum. I guess it will take time for more to choose this route. You won't be disappointed.