NB6 Motor into an NA6, Whats involved?

[CheyneX5]

This is something i have been curious about for a while...

I know that SuperMazdaKart did this a while back, but i could not find enough relevant info on the topic.

So, I am in a position where my engine is about to tick over to 200,000kms. There is still plenty of life in there, it goes well enough but it feels tired at some points. It's drives like a truck when it's cold and the lifters will chatter and the drop of a hat. It can occasionally hesitate too. Not to mention it got a little hot at winton.

This got me thinking about engines and what i should do. First of all, a bit of history. My old NA6 suffered from the infamous SNC issue. I took the option of replacing the motor with a Long Nose motor with very low KM's. This was not the cheapest option, but definitely the best, it was perfect and ran flawlessly.

As it is coming to the time again, do i just do the belt? Or do i do the whole "do it once, do it properly mantra"?

This then brings up the topic of this thread. If i can find a good one, which there is currently one for sale in Melbourne at the moment, should i get and NB6 motor? I have heard good things about them. But it also lists some concerns... Things like ECU, AFM, Wiring Loom, Intake Piping etc

Can anyone shed some light on this?

Thanks,

Cheyne

[timk]

You need to notch the exhaust cam to drive the CAS. Jeremy (jerrah) on here has done the swap.

[jerrah]

If you swap all the NA6 gear over and modify the intake cam to take the CAS it'll run like it's supposed to be there. The engine for sale here already has these mods done doesn't it? MX5plus in Brisbane modified my cam for me.

If you modify the cam and swap on your NA6 intake manifold, pulleys, valve cover and I think the thermostat housing was different. (I've since done a coolant reroute and blocked off the front outlet)

Interestingly I found when I did my water pump the NB6 uses the BP waterpump and not the NA6 waterpump. The NA6 pump was missing a bolt hole for the alternator or something important from memory though that may be specific to my set up. I'm running the NA6 alternator and crank pulleys obviously.

I've had a NB B6 in my car now over what must be 2+ years but I've since gone a little silly with the modifications.

I'm now running NB6 intake manifold, NB8 throttle body and TPS, NB6 headers (bigger diameter than the NA6) into a SE 'mazdaspeed' catback, 6 speed and other interesting things.

If you have any questions feel free to ask and I'll do my best to remember.

[Okibi]

Interesting to read the NA6 intake manifold is a direct bolt on to the NB6 engine, i'd have thought they'd have changed head design as they did on the NB8.

[daffyflyer]

Correct me if I'm wrong, but wouldn't a NB8 motor fit and give you more poworz (tm)?

[timk]

You need to notch the exhaust cam to drive the CAS. Jeremy (jerrah) on here has done the swap.

If you swap all the NA6 gear over and modify the intake cam to take the CAS it'll run like it's supposed to be there.

My bad, you are right when you said intake cam; I've been looking at 1800 engines for too long!

[jerrah]

NB6 head is different and has solid lifters but the intake and exhaust manifolds are a direct bolt on.

NB8 engine swap would be considerably more work especially if the OP wants to retain factory ECU etc? I have seen NA8 motors in NA6's running stock throttle bodies with an adaptor and original ECU. Despite the power difference I've found at the track NB8's and the NA6 (with the NB6 motor) are pretty evenly matched for acceleration which makes for a frustrating overtaking proposition.

I have no idea if there is a power/torque difference between the NA6 and NB6 B6's but with solid lifters it should have a higher theoretical redline. That said I never found much benefit revving out the NB6 and my lap times were better if I shifted at 6500rpm.

[daffyflyer]

Surely if you had a full NB8 motor and loom/ecu it wouldn't be that hard, although I guess new exhaust would be in order, and probably a diff if you didn't want to explode the old one.

[SuperMazdaKart]

i had details of my na6 to nb6 swap ages ago at http://www.mx5cartalk.com/phpBB-3.0.2/viewtopic.php?f=18&t=32405&p=416932&hilit=nb6#p416932 but some server swap or something that link doesn't work anymore.

[jerrah]

Surely if you had a full NB8 motor and loom/ecu it wouldn't be that hard

You'd need to swap the alternator since the NA6 is self regulated, and then the dashboard probably wouldn't work right off the new ECU. You'd need to splice into the wiring/switches so the pop-up lights worked, the later models had a immobiliser built into the key which talks to the ECU so you'd need to swap in the key/ignition to match the ECU. The ECU would then require various other sensors/wiring installed or it would be throwing codes. Starting to sound like selling the NA6 and buying a NB8 would be much easier.

Of course if you dropped in the NB8 motor and used an aftermarket computer that would be a different story.

[93_Clubman]

i had details of my na6 to nb6 swap ages ago at http://www.mx5cartalk.com/phpBB-3.0.2/viewtopic.php?f=18&t=32405&p=416932&hilit=nb6#p416932 but some server swap or something that link doesn't work anymore.

now available here:
http://www.mx5cartalk.com/forum/viewtop ... b6#p416932

[bensale]

Why not wait a while... Your engine really isn't that bad... Instead of the nb6 motor buy a nb8 motor and actually gain some performance out of all the hassle and effort you're going to go to... It just seems silly, especially as it's a swap I don't think you actually need to do... As you say "there is still plenty of life in there, it goes well enough" I think it has the same if not a bit more grunt than mine and apparently my car is a "jet"...

It's drives like a truck when it's cold and the lifters will chatter and the drop of a hat.

Change the oil you're using... I don't know what your mechanic puts in it... Learn to do the oil yourself and find something which works for your car...

It can occasionally hesitate too.

Plugs, leads, ignition timing, fuel filter, air filter, put some injector cleaner through, throttle cable tension etc...

Not to mention it got a little hot at winton.

Cooling system... I would say your radiator coolant needs changing... Nulon sell concentrate which says it's for motorsport use on it... I just put some in before PI and it seems to work well mixed as directed with distilled water... The concentrate was $10, the water $4 for 5L... It look 10 minutes to change...

[CheyneX5]

If you swap all the NA6 gear over and modify the intake cam to take the CAS it'll run like it's supposed to be there. The engine for sale here already has these mods done doesn't it? MX5plus in Brisbane modified my cam for me.

If you modify the cam and swap on your NA6 intake manifold, pulleys, valve cover and I think the thermostat housing was different. (I've since done a coolant reroute and blocked off the front outlet)

Interestingly I found when I did my water pump the NB6 uses the BP waterpump and not the NA6 waterpump. The NA6 pump was missing a bolt hole for the alternator or something important from memory though that may be specific to my set up. I'm running the NA6 alternator and crank pulleys obviously.

I've had a NB B6 in my car now over what must be 2+ years but I've since gone a little silly with the modifications.

I'm now running NB6 intake manifold, NB8 throttle body and TPS, NB6 headers (bigger diameter than the NA6) into a SE 'mazdaspeed' catback, 6 speed and other interesting things.

If you have any questions feel free to ask and I'll do my best to remember.

This is all very useful information, thanks for taking the time to write this up mate. I'm sure i will have some questions at some point. I am in the process of packing my whole house so i'm not really in the right state of mind

Surely if you had a full NB8 motor and loom/ecu it wouldn't be that hard, although I guess new exhaust would be in order, and probably a diff if you didn't want to explode the old one.

In a perfect world this would be a great idea, but i really do like the 1.6 for what it is...

i had details of my na6 to nb6 swap ages ago at http://www.mx5cartalk.com/phpBB-3.0.2/viewtopic.php?f=18&t=32405&p=416932&hilit=nb6#p416932 but some server swap or something that link doesn't work anymore.

Thanks Vu, i will have a good read of the link the 93_Clubman posted and let you know if i have any questions.

Why not wait a while... Your engine really isn't that bad... Instead of the nb6 motor buy a nb8 motor and actually gain some performance out of all the hassle and effort you're going to go to... It just seems silly, especially as it's a swap I don't think you actually need to do... As you say "there is still plenty of life in there, it goes well enough" I think it has the same if not a bit more grunt than mine and apparently my car is a "jet"...

It's drives like a truck when it's cold and the lifters will chatter and the drop of a hat.

Change the oil you're using... I don't know what your mechanic puts in it... Learn to do the oil yourself and find something which works for your car...

It can occasionally hesitate too.

Plugs, leads, ignition timing, fuel filter, air filter, put some injector cleaner through, throttle cable tension etc...

Not to mention it got a little hot at winton.

Cooling system... I would say your radiator coolant needs changing... Nulon sell concentrate which says it's for motorsport use on it... I just put some in before PI and it seems to work well mixed as directed with distilled water... The concentrate was $10, the water $4 for 5L... It look 10 minutes to change...

I appreciate everything your saying here mate, but also remember we view modifying cars from very different angles...

I have tried most things you have mentioned minus flushing the cooling system, replacing the fuel filter, replacing the radiator and using injector cleaner. I am sure that most of these things will make an improvement... I will get around to them as well.

The reason i enquired about the NB motor is because i saw the one for sale here and i was curious what was involved (the original title of this thread). I would happily go for another B6 but it was interesting to see what people had to say about the NB6. It's something i will consider for down the track.

For now, yes, my motor is fine. But if it works out to only cost a bit more to replace it when the timing belt eventually goes, i will.

While your taking a very track based approach to your car, i can understand why your not to fussed about minor performance loss and age of your engine. I am a little more fussy, i don't really have a reason to be, but i do want everything to be the best it can be. My Roadster was a prime example. As the car is also a daily driver, i want it to be exactly how i want it, in the best possible condition.

Thanks for your input none the less though, it has made me decide to go and get this cooling issue sorted.

[bensale]

Yes I know we have different views but really both our views are means to the same end. It's just that I guess I take an approach a little different to most in some cases and am very value conscious and will take 90% of the result for 50% of the price over 100% of the result for 100% of the price. If you needed an engine now a NB6 would be an amazing option, but I can see you spending a lot of money for next to no gain if you're not careful, especially as you don't have the facilities to do the work yourself.

It's not that I'm not fussed with minor performance loss, the opposite really, it's just that I find through taking the time to tinker with various things you can get back a lot of the loss which occurs with age... Could be a good idea to pop a spark plug out and have a look at it. When was the last time them and the leads were done?

With the HLA noise, I've always noticed your car has quite low oil pressure at idle... This would be the reason for the prolonged HLA noise as I would say that there is not enough oil pressure to get the oil in there quickly at start up and to clean out the old oil in there. This could mean that the HLAs have partially or completely failed. The first thing I would try is a good 10w-40 grade oil (or there abouts, I ran 0w-50 Elf for a while when I could buy it wholesale), I bought some shell stuff for my last oil change as I wanted to try something new and i have had no HLA noise with the oil and have also noted that my oil pressure it a bit higher with this oil. If it still makes a lot of noise you may need to replace the lifters, or deal with it...

Changing the coolant will probably really help with the overheating issue.

[93_Clubman]

Cheyne, you're possibly already aware, but a number of forumites have had excellent results using 'Nulon Lifter Free'.

Re hesitation, of course there are a number of possibilities, but here's a recent one that either causes hesitation or starting issues & may be related to fuel filter issues:
viewtopic.php?f=55&t=46425

If you're not sure when the fuel filter was last replaced, then it's well worth doing, & Repco can sell you one for $30 or so.

Re NB6 motor, again you're possibly already aware, but there were a few versions which may be referred to as an NB6 motor, with differences of output:
viewtopic.php?f=53&t=45725&p=576556&hilit=nb6#p576556