info needed NB6 engine

[ferg]

Hi all,

I have an NB6 engine (ex Japan) which I believe is a "fuel economy" version sold only in Japan and possibly parts of Europe. It's got 86k on it (a bit less than the 304k 1600 in my NA). Does anyone know any info on this engine? I know of one being put into a local car using the original cams and drive off the rear of the cam, NA inlet manifold (I THINK) etc. From the little info I have gathered, it appears to have about 10 kw LESS than the original NA - I wonder how much of this is engine management and how much is hard to change issues like head, cams, etc.

At first I thought (hoped!) it was simply a 1600cc version of the 1800cc engine but I'm starting to have doubts and suspect there may be many differences apart from simply capacity.

Any info much appreciated. Thanks

[zossy1]

There is lots of info out there on this engine and this swap into an NA6.

AFAIK the engine uses solid lifters and an NB-style intake and exhaust manifold. It also uses an NB-style CAS mounted on the exhaust side of the head. These are your primary problems.

This necessitates the use of the NB-style intake and exhaust manifolds, and a cam, cam cover and CAS swap from your NA6 into the NB6 engine (or suitable modification of your loom and engine management to accommodate the NB6 CAS, which I cannot comment on and can't say if this is even possible).

From there, you may also need to swap in the TB from the NA6 intake so that you can run it into your loom.

Do some searching to confirm this though. We have a complete wrecked NB6 with engine and gearbox which we will be using for a swap in the future and I am 80% sure I am right but I would trust someone who has actually done the swap. We will be using the complete NB6 loom and ECU for our swap though, and possibly the NB6 dash too.

Assuming I am right, using your worn NA6 cams will present an obvious problem.

[sailaholic]

If it is an nb6 it will be a bp6 engine. Ie a 1600 version of the nb8. Na6 / b6 manifolds will not fit. Engine should have solid cams and solid "lifters".

Charlie 91 put one in his car and may know more.

Sent from my GT-I9100 using Tapatalk

[geofiz]

I have just dropped a BP4W into my NA8, and it seems to run on the NA8 ecu. No radiator in as yet, but it starts and idles OK.

to get it working, I swapped the following components from the NA8 onto the BP4W.

1. throttle body (bolts straight onto the new manifold)
2. Alternator.
3. started motor (3.5 lbs lighter)
4. CAS and valve cover from NA8.
5. Coil pack
6. ECU temperature sensor (under coil pack, 2 wires on plug)

The biggest hassle was the fule rail as the NA8 has a fuel return system, the BP4W motor runs a returnless fuel system. If you have the rail from a 99-00, then it is easy, as the pressure regulator/return line from the NA8 can can be bolted onto the fuel rail from the 99-00.

Everythins else was relatively pnp.

[zossy1]

4. CAS and valve cover from NA8.
5. Coil pack
6. ECU temperature sensor (under coil pack, 2 wires on plug)

I wonder if he will be able to use the NB6 intake cam with switching the CAS to the other side...? I can see how this would have worked with an NA8 as the NA8 used the exhaust cam for CAS operation whereas the NA6 uses the intake cam...

We need Charlie to comment on this one.

[Steampunk]

Richard at MX-5Plus has sold over a dozen of these.

[ferg]

Guys, many thanks for your input thus far....my car is an 89 NA with (as far as I know) the original 1600cc engine. Measuring (roughly) the bolt centers on the exhaust manifold in the car and the possible Japanese engine on the engine stand, they seem near as damn identical, indicating a probable similar bore centers. My assumption therefore is the NA manifolds would bolt on - I realize this is probably a rash assumption, but live in hope!

If this proves to be the case, it would appear that the NA CAS would retro-fit providing I slotted the rear of the driver's side cam to drive it. The cam housing has a knock out in it to allow this.

Other bits and bobs look like they can be "engineered", as Geofiz has confirmed (with exception of problematic fuel rail), however, I still have concerns that the little info I have been able to find indicates the newer engine makes 80 kw while the original makes 90 (I think). I have assumed up till now that it likely has wimpy cams and management to achieve good fuel economy at the expense of power - any thoughts on this?

For reference, the engine in my car is serial numbered BG583268 while the potential; replacement engine is numbered B6 941220.

I guess the eventual decision is swap over the NB6 engine OR, get hold of an acceptable NA engine and freshen it or the original engine up while I keep the car mobile. Not looking to do major mods just to get the best out of whats there and achieve good reliability. While more power never goes astray, what is there is pretty acceptable if it keeps going reliably.

Your input greatly appreciated.

[sailaholic]

Replacement engine is not a NB engine. manifolds don't swap as bore spacing is different. nb engines are numbered bp to my understanding. So looks like you've got a b6 engine.

Charlie will be able to be definitive though.

Sent from my GT-I9100 using Tapatalk

[geofiz]

Sounds right, mine was a NA8 - NB8B swap.

[ferg]

Thanks. Numbers cast in back of head say "b660" so I guess that confirms it. The engine has been marked by the guy I got it off (he removed it from wreck in Japan) as NB6 but this is presumably wrong. He previously fitted one the same to a customers car and used the NA original cams so the CAS was dríven in original place - said it rattled a bit in the top end - this (kind of) suggests solid lifters.

As I know stuff all about these engines, was there a B6 with solid lifters? If my reading between lines is correct, could it be that the motor I have will be a/ easier to fit (as I can use many existing bits) and b/ NOT a fuel economy model and therefore worth having? Or am OI being too optimistic?

As a matter of interest, the engine is marked with about 80k on it - any idea what year model it's likely to be out of?

Thanks again and apologies for the dumb questions.

[93_Clubman]

nb engines are numbered bp to my understanding.

NA8 & NB8 engine numbers start with BP. The 'BP' denotes a 1.8 motor. NA6 & NB6 start with B6 - B6 denotes a 1.6 motor:
viewtopic.php?f=29&t=43856&p=558312&hilit=engine+number+nb6+B6#p558312

NB6 versions:
viewtopic.php?f=53&t=45725&p=576556&hilit=nb6#p576556

http://www.roadster.jp/

NA6 to NB6 swap:
http://www.mx5cartalk.com/forum/viewtop ... b6#p416932

viewtopic.php?f=29&t=46526&p=584869

viewtopic.php?f=29&t=44290

NB6 v NA6 ECU pinout:
viewtopic.php?f=76&t=38367&p=498494

[mrpham]

I've put a NB6 engine in my NA6, I purchased it from MX5 Plus and Richard gave me most of my info on how to do it.

http://omgpham.com/my-new-engine-nb6
http://omgpham.com/engine-swap-completed

Pretty straight forward process, and the NB6 engine uses the same block as the NA6. Differences are the head, exhaust, intake and accessories.

[ferg]

Thanks heaps all for comprehensive info. Mrpham, do you know what the horsepower/kw the NB6 makes? Any noticeable difference up or down on your previous engine?

Thanks all.

[mrpham]

Thanks heaps all for comprehensive info. Mrpham, do you know what the horsepower/kw the NB6 makes? Any noticeable difference up or down on your previous engine?

Thanks all.

Hey mate,

Read that it makes more power but don't think it really does. It would make more power if you were to use the NB6 intake and ECU, but means you need the NB6 harness too.

Compared to my old engine, this NB6 has less ks on it and feels "fresher" and makes more power. Only reason I swapped was because my head was warped and soft, oil control rings were gone as well as the valve springs and valve stem seals.

[93_Clubman]

...do you know what the horsepower/kw the NB6 makes?

viewtopic.php?f=53&t=45725&p=576556&hilit=nb6#p576556