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NB motor in NA is waste of money ?

5K views 18 replies 11 participants last post by  jdmfc3s90 
#1 ·
Hi,

I have a 1994 miata with a stock BP engine.
If I update this motor with pieces like high compression ratio piston, cams, IRTB ... What power outup can I expect compare to the same setup on a NB engine?

I mean, is the engine itself is really better?

Cause I don't want to spend my money in an engine that will only give me 5 more horsepower.


I hope you will understand what I was trying to say. My english is terrible. :woolery:
 
#2 ·
the engine block from 1994 to 2005 is basically the same, but the heads on NB BP's are definitely better in every way. Try to just find a 99-00 1.8 engine head and do your build the same way, but just add that. The 01-05 head has even more potential for gain, if you want to mess with it's capability of variable valve timing.
 
#12 ·
the engine block from 1994 to 2005 is basically the same.
Not really, every revision of the car has a better bottom end (for N/A power).. Compression on the NA 1.8 is lower than the NB1 1.8, and compression in the NB1 1.8 is lower than the NB2 1.8. For N/A horsepower, your best bet is an NB2 engine, with either the NB2 head (if you can control VVT) or a BP4W head from the NB1 (if you can't control VVT).
 
#4 ·
best combo is an 01 bottom with a 99-00 head.
 
#7 ·
May I ask you why ? :^)

Because you get the 10:1 compression of the 01+ block vs. 9.5:1 of the 99-00 block. Plus the 01+ blocks have the main bearing support plate (MBSP). This helps prevent flexing in the rotating assembly and helps when dealing with higher revs.

http://www.solomiata.com/MBSP.html

Also, you don't have to worry about VVT wiring and aftermarket ECU control for. If you consider that a plus or not.

I am currently in the process of swapping an 01+ block into my 99 Miata.
 
#11 ·
Lots of variables to consider when predicting output at the wheels. Stock ECU (which one) or standalone? If the latter, how good is the tune? How many miles on the piston rings? I/H/E? If so, which ones? blah blah blah

Head over to miata.net and look at the dynos & timesheets subforum of Power Mods or whatever it's called. You'll need to extend the date range of the search, though. From there, you can pretty much just check the subject lines to find what you're craving.
Now, as an idea to the potential of this combo, look at the engine that Emilio @ 949 Racing put together for the OGK and now has in the rental. There are a few add-ons to the engine, like a 'speed intake cam, imported intake manifold, a little bit of head work...oh, and AEM engine mgmt. Aside from the manifold, everything he's got going there is readily available.
 
#18 ·
MBSP can be an intresting value add. But I think I can order the MBSP it self
And I agree that the coolant reroute is the real solution to fix this problem.

For the VVT, I know there is the Hydra from Flyin' Miata.

I will try to find this thread on miata.net about the dynos.

Ok, I think I will try to find a 01+ head only. It's no need to buy a complete engine for it's 10.1/1 compression if I want to replace the piston for some 11.0/1 piston
 
#19 ·
Some one correct me if im wrong, but between all years even jdm stoke, bore and piston size are all the same. If this is true, why not get 01+ block, jdm 01+ pistions has 10.5:1 compression, and add a 99 head. With thinner head gasket and some shaving of the head (if necc.) you can possibly get a 11:1 compression with out really building the motor. No need dealing with VVT wiring you get the strengh of the nb2 block, the flow with 99 head and and more power with the bump of compression. Not sure what type of ecu to run, i think i would go megasquirt.
 
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