99-00 vs 01-05 BP Reliability
#1
![Question](https://www.miataturbo.net/images/icons/icon5.gif)
Any consensus as to whether or not the 01-05 motors are more reliable than the 99-00 motors? In particular, im referring to the bottom-end. I only got ~140k out of my `99's BP bottom-end before I wore away #3 rod bearing. Took the entire motor apart for a rebuild.
I installed ARP head studs and like a moron, did not bother installing ARP main studs and now its too late.. I dont want to tear it apart to line-bore the main journals.
Then I keep going back and fourth as to whether or not I should buy a MBSP and 01-05 oil pan. It seems that the wisest choice would be to (in hindsight) install the ARP main studs as everyone I've spoken to thinks the MBSP is too flimsy to do much of anything.
I'm not building for major power, just high RPM reliability.
Anyone care to chime in?
I installed ARP head studs and like a moron, did not bother installing ARP main studs and now its too late.. I dont want to tear it apart to line-bore the main journals.
Then I keep going back and fourth as to whether or not I should buy a MBSP and 01-05 oil pan. It seems that the wisest choice would be to (in hindsight) install the ARP main studs as everyone I've spoken to thinks the MBSP is too flimsy to do much of anything.
I'm not building for major power, just high RPM reliability.
Anyone care to chime in?
#7
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i think the thrust bearing problem was a manufacturing defect where they did not machine the tolerances properly, too much play, but i cannot confirm that. fortunately my motor did not show any symptoms of wear with the thrust bearings.
the problem i ran into, however, was con rod bearing #3 which wore away badly. the motor would knock over 3k and would stop if you mashed the gas pedal. i diagnosed the bearing by manually turning the motor and upon downstroke, i could shove a metal rod into the compression chamber (remove sparkplug) and you could actually push the piston down a mm or two.. you would feel/hear the play.
so i guess the MBSP is overrated.. and unfortunately i didnt install the ARP main studs. :(
oh well, another 150k, hopefully i can squeeze more juice out of this lemon.![](https://www.miataturbo.net/images/smilies/smile.gif)
edit: i may just drill, tap and plug the oil pan, that way going turbo will be a cinch in the future if i decide to go that route.
the problem i ran into, however, was con rod bearing #3 which wore away badly. the motor would knock over 3k and would stop if you mashed the gas pedal. i diagnosed the bearing by manually turning the motor and upon downstroke, i could shove a metal rod into the compression chamber (remove sparkplug) and you could actually push the piston down a mm or two.. you would feel/hear the play.
so i guess the MBSP is overrated.. and unfortunately i didnt install the ARP main studs. :(
oh well, another 150k, hopefully i can squeeze more juice out of this lemon.
![](https://www.miataturbo.net/images/smilies/smile.gif)
edit: i may just drill, tap and plug the oil pan, that way going turbo will be a cinch in the future if i decide to go that route.
#8
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Here is what you're looking for:
http://www.miata.net/solo/99miatathr...ngfailure.html
As for the MBSP, Mazda put it there for a reason, although most earlier BPs have been running fine without stronger ARP main studs OR a MBSP. The newer MZR engine also now has a single complete assembly to support all the main bearings, so there has to be good reasoning for supporting the mains. My personal opinion is that you will be fine without either; the BP has been able to withstand >7000rpm even after rebuilds without either. Oh yeah, don't worry about line boring... the block itself is very stable and will generally maintain the proper bore for the main journals indefinitely, or at least I have never read of a clearance problem.
Keep in mind if you ever decide to install BOTH the ARP main studs AND the MBSP, you will either have to file the studs (not recommended) or drill the pan out for clearance because it won't fit.
![Name: 429404776_e45b8435d6.jpg
Views: 335
Size: 32.4 KB](https://www.miataturbo.net/attachments/engine-performance-56/195869d1501233362-99-00-vs-01-05-bp-reliability-429404776_e45b8435d6.jpg)
The BP is an iron horse. As long as you have your tolerances in check, there will never be a reliability issue.
http://www.miata.net/solo/99miatathr...ngfailure.html
As for the MBSP, Mazda put it there for a reason, although most earlier BPs have been running fine without stronger ARP main studs OR a MBSP. The newer MZR engine also now has a single complete assembly to support all the main bearings, so there has to be good reasoning for supporting the mains. My personal opinion is that you will be fine without either; the BP has been able to withstand >7000rpm even after rebuilds without either. Oh yeah, don't worry about line boring... the block itself is very stable and will generally maintain the proper bore for the main journals indefinitely, or at least I have never read of a clearance problem.
Keep in mind if you ever decide to install BOTH the ARP main studs AND the MBSP, you will either have to file the studs (not recommended) or drill the pan out for clearance because it won't fit.
![Name: 429404776_e45b8435d6.jpg
Views: 335
Size: 32.4 KB](https://www.miataturbo.net/attachments/engine-performance-56/195869d1501233362-99-00-vs-01-05-bp-reliability-429404776_e45b8435d6.jpg)
The BP is an iron horse. As long as you have your tolerances in check, there will never be a reliability issue.
#9
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I've killed both a '99 and '03 stock blocks.
The 01-05 MBSP should yield a tiny amount less crank play/vibration in high RPMs.
The ARP main studs are definitely more beneficial than MBSP... As previously mentioned Mazda screwed up the thrust bearing tolerance on 99-00's (too loose.)
If your building for reliable high RPMs, an ATI Damper & Boundary Engineering oil pump are worth looking into. A balanced/forged rotating assembly would be smart too... Honda VTEC's these engines are not.
I still have the '03 block (pan, MBSP etc) if your interested.
The 01-05 MBSP should yield a tiny amount less crank play/vibration in high RPMs.
The ARP main studs are definitely more beneficial than MBSP... As previously mentioned Mazda screwed up the thrust bearing tolerance on 99-00's (too loose.)
If your building for reliable high RPMs, an ATI Damper & Boundary Engineering oil pump are worth looking into. A balanced/forged rotating assembly would be smart too... Honda VTEC's these engines are not.
I still have the '03 block (pan, MBSP etc) if your interested.
#10
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Al nailed it. Pretty much if you think your engine is going to be used for high stress applications, it would be wise to invest in the above mentioned. If you are just daily driving with the occasional fun run, you shouldn't worry about it, although it doesn't hurt to have insurance. I am not sure about your #3 rod bearing failure, however. That's peculiar.
![Dunno](https://www.miataturbo.net/images/smilies/dunno.gif)
#11
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
I've killed both a '99 and '03 stock blocks.
The 01-05 MBSP should yield a tiny amount less crank play/vibration in high RPMs.
The ARP main studs are definitely more beneficial than MBSP... As previously mentioned Mazda screwed up the thrust bearing tolerance on 99-00's (too loose.)
If your building for reliable high RPMs, an ATI Damper & Boundary Engineering oil pump are worth looking into. A balanced/forged rotating assembly would be smart too... Honda VTEC's these engines are not.
I still have the '03 block (pan, MBSP etc) if your interested.
The 01-05 MBSP should yield a tiny amount less crank play/vibration in high RPMs.
The ARP main studs are definitely more beneficial than MBSP... As previously mentioned Mazda screwed up the thrust bearing tolerance on 99-00's (too loose.)
If your building for reliable high RPMs, an ATI Damper & Boundary Engineering oil pump are worth looking into. A balanced/forged rotating assembly would be smart too... Honda VTEC's these engines are not.
I still have the '03 block (pan, MBSP etc) if your interested.
my low post count restricts me from being able to PM.
thanks for the input guys. i assume we can all agree though that if one is to install the arp studs, the block NEEDS to be line-bored right?
mike
#13
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at moderate turbo power levels (250rwhp), the rods in both NB blocks will turn into wavy gravy. I'd bet a lot of money that those of us without boosted NB motor failures have at least one or more non-straight rods in our motors--even if they appear to work fine.
Now... I wonder if that slight bend in a rod in a working motor can upset the bearing surfaces enough to cause significant wear on the bearing before any rods fail. Once the rods are not cylindrical to the crank, it's recipe for ... well, a new motor.
Now... I wonder if that slight bend in a rod in a working motor can upset the bearing surfaces enough to cause significant wear on the bearing before any rods fail. Once the rods are not cylindrical to the crank, it's recipe for ... well, a new motor.
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