Best engine for turbo?
07-12-2015, 11:04 AM
#3
Cpt. Slow
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Miatas don't have 8v or 1.9 engines.
The short answer is 1.8, they spool quicker than the 1.6. The longer answer is a 94 NA8 with '99 head. You'll have your oil feed, good flow, lower compression, and no VVT complication.
The short answer is 1.8, they spool quicker than the 1.6. The longer answer is a 94 NA8 with '99 head. You'll have your oil feed, good flow, lower compression, and no VVT complication.
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07-12-2015, 11:48 AM
#4
Boost Pope
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Before I begin, here is an oil painting of an eggplant set upon a wooden block:
That having been said...
The simple fact is that the Miata platform pretty much got better every year (or, every few years at least) from its introduction in 1990 until 2005. The major groups, in order from least desirable to most desirable:
90-93: Weaksauce 1.6 engine, fragile differential.
94-95: 1.8 engine, but still with a crappy head on it. Good differentials.
96-97: Same as 94-95, but with OBD-II electronics. Can be a good thing or a bad thing depending on your preferences.
99-00: Major engine upgrade (better head), major chassis stiffness upgrade.
01-05: Same head, but now with variable intake cam timing, slight chassis upgrades.
At no point in the car's history (until 2006) did a new model year incorporate a change which represented a significant downgrade from the prior year. Yes, the cars slowly gained weight over the years, but this was more than offset by improvements in both engine power and chassis stiffness. I personally think that the interiors of the '90-'97 cars were a bit nicer than those of the '99-'05 cars, but this is an aesthetic judgement rather than a technical one. As Curly noted, you can piece together an "ultimate" engine using parts from various years as well as certain aftermarket components, but viewed as a complete assembly, the later cars and engines were always an improvement over the earlier ones.
That having been said...
The simple fact is that the Miata platform pretty much got better every year (or, every few years at least) from its introduction in 1990 until 2005. The major groups, in order from least desirable to most desirable:
90-93: Weaksauce 1.6 engine, fragile differential.
94-95: 1.8 engine, but still with a crappy head on it. Good differentials.
96-97: Same as 94-95, but with OBD-II electronics. Can be a good thing or a bad thing depending on your preferences.
99-00: Major engine upgrade (better head), major chassis stiffness upgrade.
01-05: Same head, but now with variable intake cam timing, slight chassis upgrades.
At no point in the car's history (until 2006) did a new model year incorporate a change which represented a significant downgrade from the prior year. Yes, the cars slowly gained weight over the years, but this was more than offset by improvements in both engine power and chassis stiffness. I personally think that the interiors of the '90-'97 cars were a bit nicer than those of the '99-'05 cars, but this is an aesthetic judgement rather than a technical one. As Curly noted, you can piece together an "ultimate" engine using parts from various years as well as certain aftermarket components, but viewed as a complete assembly, the later cars and engines were always an improvement over the earlier ones.
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07-13-2015, 11:33 AM
#5
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Best bottom end if you're using forged rods/pistons: any 1.8L is fine
Best bottom end if you're staying stock: 94-97 due to slightly lower compression
Note: 94-95 bottom end has a convenient oil port below the exhaust mani, but running a stainless line from the oil pressure port on the other side of the engine is easy
Best head: 99+, 99-00 if you can't control VVT
Best intake: flat top 99+ intake
Best crank: stock
Best oil pump: not stock
Things to beware of: 96-97 cars are not plug and play with the MS PNP3, which is the best off the shelf way of controlling VVT. The 96-97 cars generally have fewer off the shelf options available since they have the shitty heads of the pre-99 years combined with the annoyance of an OBD2 compliant ECU with its own weird harness. Any of these issues can be worked around with enough perseverance (heads can be swapped, wiring harnesses can be fabricated, etc) but it's easier to just pick the right stuff in the first place. Of course, once you're messing with the bottom end, you can basically swap the head for free.
The 2nd gen (NB) cars tended to have higher and higher compression ratios as the years go on and the 2002 and up bottom end was prone to broken rods (under boost). But as far as I know, swapping out the rods/pistons on these cars leaves them as strong as any other years.
Weak spots on all miata engines:
Thrust bearing will eventually die after you install an upgraded clutch if you don't do the clutch disconnect. I lost my first motor from this.
94-97 seem ok with stock internals up to about mid 200s at the wheel, higher years get progressively weaker, especially 2002 up. Stock internals can survive a lot of power BUT they are marginal and will eventually give way with sufficient abuse over time.
Once you start revving (or plan to) over 7k RPM, replace harmonic balancer and oil pump or they will eventually die. Oil pressure loss is not your friend.
Stock fuel rail is rubbish past 250whp.
Stock cooling design is an awful figure 8 design that leaves the back half of the engine much hotter than the front, with the coolant sensor at the coldest part of the engine. Do the coolant reroute or you're gonna have a bad time. This means putting the sensor at the back of the head and blocking off the passage at the front. If you don't do this, you're still gonna have a bad time.
You need to run an aftermarket ECU and WBO2 at a minimum or you're basically just guessing at what is going on.
Best bottom end if you're staying stock: 94-97 due to slightly lower compression
Note: 94-95 bottom end has a convenient oil port below the exhaust mani, but running a stainless line from the oil pressure port on the other side of the engine is easy
Best head: 99+, 99-00 if you can't control VVT
Best intake: flat top 99+ intake
Best crank: stock
Best oil pump: not stock
Things to beware of: 96-97 cars are not plug and play with the MS PNP3, which is the best off the shelf way of controlling VVT. The 96-97 cars generally have fewer off the shelf options available since they have the shitty heads of the pre-99 years combined with the annoyance of an OBD2 compliant ECU with its own weird harness. Any of these issues can be worked around with enough perseverance (heads can be swapped, wiring harnesses can be fabricated, etc) but it's easier to just pick the right stuff in the first place. Of course, once you're messing with the bottom end, you can basically swap the head for free.
The 2nd gen (NB) cars tended to have higher and higher compression ratios as the years go on and the 2002 and up bottom end was prone to broken rods (under boost). But as far as I know, swapping out the rods/pistons on these cars leaves them as strong as any other years.
Weak spots on all miata engines:
Thrust bearing will eventually die after you install an upgraded clutch if you don't do the clutch disconnect. I lost my first motor from this.
94-97 seem ok with stock internals up to about mid 200s at the wheel, higher years get progressively weaker, especially 2002 up. Stock internals can survive a lot of power BUT they are marginal and will eventually give way with sufficient abuse over time.
Once you start revving (or plan to) over 7k RPM, replace harmonic balancer and oil pump or they will eventually die. Oil pressure loss is not your friend.
Stock fuel rail is rubbish past 250whp.
Stock cooling design is an awful figure 8 design that leaves the back half of the engine much hotter than the front, with the coolant sensor at the coldest part of the engine. Do the coolant reroute or you're gonna have a bad time. This means putting the sensor at the back of the head and blocking off the passage at the front. If you don't do this, you're still gonna have a bad time.
You need to run an aftermarket ECU and WBO2 at a minimum or you're basically just guessing at what is going on.
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07-13-2015, 12:06 PM
#6
The 2nd gen (NB) cars tended to have higher and higher compression ratios as the years go on and the 2002 and up bottom end was prone to broken rods (under boost). But as far as I know, swapping out the rods/pistons on these cars leaves them as strong as any other years.
94-97 seem ok with stock internals up to about mid 200s at the wheel, higher years get progressively weaker, especially 2002 up.
Stock fuel rail is rubbish past 250whp.
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07-13-2015, 01:42 PM
#13
Boost Pope
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There's a difference between being an ******* and being wrong. Concealer was not wrong.
There's no evidence in 10+ years of boosting NBs that the connecting rods became progressively weaker over the years. In fact, a careful perusal of the Mazda factory parts catalogs reveals the exact same part number (B6S7-11-210E) listed for all engines from 1994-2002. (2002 is the last catalog I have access to, so that doesn't mean that they changed in 2003, merely that I have no proof that they didn't. I'm about 90% certain that only the MSMs used different rods from the rest of the BPs.)
There is some highly anecdotal evidence that the later engines are slightly more prone to failure under extreme acts of turbocharging, however this is mostly confined to piston damage and attributable to a combination of the higher compression ratio along with the fact that, until fairly recently, relatively few good engine-management solutions existed for these engines, leading some people to run them at stock timing, or with only a small mechanical retard dialed in by way of an adjustable crankplate.
As to the fual rail, opinions here seem to be poorly-informed, and based largely on the fact that a number of vendors sell extremely pretty pieces of machined aluminum which they claim are vastly superior to the stock part. Numerous people on this forum have made large amounts of power on the stock rail, albeit with other fuel system modifications required in the NB cars, such as conversion to a return-regulator configuration as found on the NAs.
There's no evidence in 10+ years of boosting NBs that the connecting rods became progressively weaker over the years. In fact, a careful perusal of the Mazda factory parts catalogs reveals the exact same part number (B6S7-11-210E) listed for all engines from 1994-2002. (2002 is the last catalog I have access to, so that doesn't mean that they changed in 2003, merely that I have no proof that they didn't. I'm about 90% certain that only the MSMs used different rods from the rest of the BPs.)
There is some highly anecdotal evidence that the later engines are slightly more prone to failure under extreme acts of turbocharging, however this is mostly confined to piston damage and attributable to a combination of the higher compression ratio along with the fact that, until fairly recently, relatively few good engine-management solutions existed for these engines, leading some people to run them at stock timing, or with only a small mechanical retard dialed in by way of an adjustable crankplate.
As to the fual rail, opinions here seem to be poorly-informed, and based largely on the fact that a number of vendors sell extremely pretty pieces of machined aluminum which they claim are vastly superior to the stock part. Numerous people on this forum have made large amounts of power on the stock rail, albeit with other fuel system modifications required in the NB cars, such as conversion to a return-regulator configuration as found on the NAs.
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07-13-2015, 01:56 PM
#14
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Still, I would have appreciated something more informative than "nope." I honestly had no idea the stock rail wasn't a POS or that the 2002+ engines weren't crappy. It probably didn't help that those failed cars were probably running FM piggybacks 10 years ago.
edit: Joe Perez, thanks for the information you posted while I was typing this
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07-13-2015, 02:00 PM
#16
I haven't been on the miata-related internet for over 5 years, so it's possible at least some of the old accepted wisdom has been disproven. Which is fine with me, I'm here to learn, not start fights.
Still, I would have appreciated something more informative than "nope." I honestly had no idea the stock rail wasn't a POS or that the 2002+ engines weren't crappy. It probably didn't help that those failed cars were probably running FM piggybacks 10 years ago.
edit: Joe Perez, thanks for the information you posted while I was typing this
Still, I would have appreciated something more informative than "nope." I honestly had no idea the stock rail wasn't a POS or that the 2002+ engines weren't crappy. It probably didn't help that those failed cars were probably running FM piggybacks 10 years ago.
edit: Joe Perez, thanks for the information you posted while I was typing this
Therefor, you could make the short logical jump to realize that the opposite was true. Within reason. I don't think anyone sane would have thought that "Nope" mean that later motors were forged from the tears of Japanese virgins and would do 1000whp unopened.
That was actually Saturday, i'm in a cautiously good mood today.
I was just busy at work and figured i'd nip that in the bud quick before some poor sap took it as truth and it got lost in the shuffle, another poor lost soul putting 94 internals in his 2005 Miata.
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07-13-2015, 02:52 PM
#19
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I was thinking your gash was slightly irregular...
I believe that our OP, Mathias, is likely a non-native English speaker and may have received all sorts of bad info elsewhere. I try to be extra nice to the foreigners because they deserve the benefit of the doubt and just because so many Americans aren't polite to perfectly nice foreigners.
So there.
I believe that our OP, Mathias, is likely a non-native English speaker and may have received all sorts of bad info elsewhere. I try to be extra nice to the foreigners because they deserve the benefit of the doubt and just because so many Americans aren't polite to perfectly nice foreigners.
So there.
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