Question of building up my engine.

[tescoking]

Hi guys, I have own this NB8B for 2 years already, and I would like to give it some extra power since it has just been stock for the last 13 years.

At the moment I just installed a K&N CAI on my car but I'm really struggling to decide on whether I should go turbo or keep building N/A with the car, or just throw a V8 engine inside.

The car is pretty much for daily driving since I haven't modify it too much, but I do believe that I will go to track one day.
So my thoughts on turbo and N/A ratio is 30/70. I am happy to have N/A because the car came out with N/A from Mazda, and I like N/A because it is a work of art. I am not saying turbo is "cheated" but I do enjoy building the car little by little, instead of chucking the whole kit in it all at once and then that's it done...nothing more to do or play around with.

The other reason is since the car is 13 years old, maybe it is time to replace the internal parts. N/A is the way to do it as it also increases the power at the same time.

I know many of you will say that turbo can give more HP with less costs than N/A, but I don't have that much money to pay it all at once for the turbo, I can only spend little by little for parts like building N/A. So guys, please correct me if I am wrong with my turbo and/ or N/A ideas.

At the end of the day I would like to know whether I should stick to my original thoughts on N/A and change all the internal parts to new and stronger parts, (also increasing the HP and extending the lifetime of the engine together, correct me if that doesn't help) quad throttle bodies, ECU, other N/A stuffs etc or just simply turbo it and let it be?

Thoughts please.
Perhaps give me some advantages and disadvantages of N/A and turbo please although I did a lot of research on that but not much is actually about MX-5.

Thanks a lot.

[Magpie]

Natural aspirated done properly is not cheap!

If you want to track your build type maybe affected by the class you would compete in.

My natural aspirated build is being done by MX5 plus and it has been a 12 month job. The decisions about the build were made in consultation with MX5 Plus, well except for the head it is their design. I found that whilst there is a lot of information out there, there is also misinformation!

Wozzah on the forum is a source of reliable information.

Are you going ITB's?

[Magpie]

Also have a look here, whilst is written for Americans it does help with the questions you need to ask yourself:

http://forum.miata.net/vb/showpost.php?p=5704021&postcount=24
Decide on a few things up front and it'll be easier for the rest of us to offer useful advice.

-Autocross, what class?
-Wheel to wheel racing or HPDE only, what class?
-Street only?
-Does it need to be emissions legal in any state? (what state)
-Must it be able to run on pump gas and if so, what octane?
-Must it run in a street car, (A/C, OEM alternator, col start driveability etc) ?
-Actual budget for everything connected to engine/power making hardware?
-Tuned by a pro or semi-knowledgeable amateur?
-You cool with the additional tuning/set up hassles of an IRTB set up?
-Does the car need to be quiet?
-Do you have a shop in mind that is familiar with race BP series builds?

Cost no object, I suspect someone could build a 300whp grenade that runs on exotic fuel. In the real world 150-190whp is doable within the budget of the most of us.

150whp is bolt-ons and a good tune. Above that you need to go into the motor.
160-165whp is just a little bowl work and compression.
170whp requires more substantial head work or mild cams or lots of compression, pick one.
185whp requires mild cams (still streetable in a VVT), compression, porting. Pick two.
195whp full head work, lots of compression and mild to medium race cams.
205whp+ is pretty much a full race engine with cams that would probably never idle for street use.
225whp+ so and the life expectancy begins to shorten. Perhaps 15-30 race hrs and you're looking at a $15-20K long block.

We have just touched 180whp on stock cams with an NB2 motor but it was not cheap. Based on the data from that experiment, I know 190whp on stock cams is possible with IRTB's, more compression and E85. At that point however, you should just feed it the cams it wants. We played with stock cams to gain a higher BFSC for endurance racing.

For most guys, I think a stock-ish cam NB2 build makes the most sense. Run as much compression as your fuel will stand, get the best ECU you can, build a Honda B series manifold grafted onto the Mazda flange, RB/Maruha/Maxim works header, fully port and polish the head. Forged everything, SUB's and heavier valve springs. That should net and easy 175whp or so, be safe to 8000rpm sustained, idle like a stocker and last 100 race hours.

[sailaholic]

If you can't afford turbo then you can't afford a Na build.

Na builds aren't that much more incremental then turbo builds. You still get to the point where most of it has to be done at once.


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[plohl]

Just get an aftermarket ecu (ms3pro, adaptronic, haltech, motec ), some bigger cams and a decent tune - should keep you happy for a while and then you can just start saving for which ever direction you want to take the build.

Some other good threads are below.

http://mx5cartalk.com/forum/viewtopic.php?f=29&t=54726
http://mx5cartalk.com/forum/viewtopic.php?f=29&t=50573

[project.r.racing]

Just get an aftermarket ecu (ms3pro, adaptronic, haltech, motec ), some bigger cams and a decent tune - should keep you happy for a while and then you can just start saving for which ever direction you want to take the build.

Some other good threads are below.

http://mx5cartalk.com/forum/viewtopic.php?f=29&t=54726
http://mx5cartalk.com/forum/viewtopic.php?f=29&t=50573

^this^

cams and ecu are both items you will upgrade no matter what direction you take. so they are both good things to do first and to build on later.

[Mr Morlock]

If you modify the car you are doing down a rocky and expensive road. The insurance cos all say advise of mods- if you do not then they will refuse to pay a claim. It's even debatable whether some mods are actually legal at all.Repairs and mods often cost a bucket of money and it all time consuming and inconvenient. If you want more power its going to be far more cost effective and convenient and legal and transparent to buy one of the official MX5 dealer or factory turbo's. Mods if extreme can also impact on a cars drivability. For those that know the engines well and have their own workshop the labour at least is minimised and for some its a hobby and interest- fair enough I get that.

Consider that just to remove an engine takes time and time equals cost- get a quote and see if it remotely makes sense for the other things that count. Insofar as driving on a track it does not matter if the car is modded or not- the MX5 has a high threshold for most of us. There are guys for example just driving regularity in a wide variety of cars and that calls for a lot of skill as well. I think Magpie provided a very good list.

[M1474]

http://www.mx5club.com.au/index.php?ID=E2013111007

Come racing.

You'll soon realise you don't want to be thrown into the deep end with the group D guys.

Deciding you need more power before taking it to the track is putting the cart before the horse.

Tyres will make you faster than tripling your hp.

Race, learn, find where your car is lacking and then you can take the modification process in the right direction.

[speed freak]

Agree to all above.

How many km are on the car/engine? It shouldn't need a rebuild yet unless its using oil or making odd sounds. You can add bosst to a engine with 200 000 km if its in good condition and been looked after.

If you go forced induction, depending on how you want to drive it you will have to look at other components such as the diff, gearbox and even brakes so you can pull it up easier etc.

Im not saying you cant or don't go forced induction but either way its going to cost a decent amount of $$ if you want to do it right. If you do it cheaply your only going to cause more dramas and cost yourself a lot more $$ down the track.

And a proper NA build is big $$ but depends on how far you want to go with it. As said above, get some bigger cams, piggy back ecu, you have CAI get a full exhaust and get it tuned. Even that will cost a bit of cash but should gain so extra ponies to keep you happy, Iv heard doing those few simple mods is quit good.

Also another way to gain more performance is, if your clutch hasn't been replaced yet or needs replacing in the near future, look into getting a B6 HD clutch and lightweight flywheel combo and even a 4.3 diff. The B6 clutch would be more suited to your NA power now but going to the smaller clutch and flywheel combo means a lot less mass has to be spun by the engine. Resulting in much better throttle response and an engine that will rev much quicker and combined with the 4.3 diff means you get even better acceleration but, it will rev a little higher on the motorway. This is the way Im going, Iv got the vvt 1.8 in stock form and my opinion its got a lot of poke now for a little 4 cyl but having less weight to spin and better gearing will have big gains.

[tescoking]

Natural aspirated done properly is not cheap!

If you want to track your build type maybe affected by the class you would compete in.

My natural aspirated build is being done by MX5 plus and it has been a 12 month job. The decisions about the build were made in consultation with MX5 Plus, well except for the head it is their design. I found that whilst there is a lot of information out there, there is also misinformation!

Wozzah on the forum is a source of reliable information.

Are you going ITB's?

Yes, I am going to ITB's but I heard that is the last step, I would love to work on N/A like you but we don't have someone like mania/mx5+ who are working and specialise on mx5 in Perth,WA

[NitroDann]

You will be disappointed by how expensive and slow a street ITB build will be, like, balls slow compared to a few grand turbo setup, which will be much nicer to drive.

Dann

[tescoking]

I am not saying turbo is not good, but compared to the N/A I can actually change the parts a little by little at different intervals whereas with the Turbo you will need to change all at once and immediately so I guess working little by little actually suits me a little better. I don't mind spending the money but my preference is to do it little by little accordingly. I really want to know is N/A and turbo which has a longer lifetime of the engine after the built, can N/A last longer because we swap in the new and stronger parts?

-Autocross, what class? I don't understand what this is, please explain.
-Wheel to wheel racing or HPDE only, what class? I don't understand what this is, please explain.
-Street only? No
-Does it need to be emissions legal in any state? (what state) No
-Must it be able to run on pump gas and if so, what octane? Fuel
-Must it run in a street car, (A/C, OEM alternator, col start driveability etc) ? Yes
-Actual budget for everything connected to engine/power making hardware? Willing to spend as long as I need to, but not in once
-Tuned by a pro or semi-knowledgeable amateur? Pro
-You cool with the additional tuning/set up hassles of an IRTB set up? Yes, I have time and patience
-Does the car need to be quiet? No, commodo is much louder than me
-Do you have a shop in mind that is familiar with race BP series builds? Not really, just a shop that do many custom cars/show cars

Cost no object, I suspect someone could build a 300whp grenade that runs on exotic fuel. In the real world 150-190whp is doable within the budget of the most of us.

150whp is bolt-ons and a good tune. Above that you need to go into the motor.
160-165whp is just a little bowl work and compression.
170whp requires more substantial head work or mild cams or lots of compression, pick one.
185whp requires mild cams (still streetable in a VVT), compression, porting. Pick two.
195whp full head work, lots of compression and mild to medium race cams. I think this is what I want at the moment
205whp+ is pretty much a full race engine with cams that would probably never idle for street use. If I could build it then why not?
225whp+ so and the life expectancy begins to shorten. Perhaps 15-30 race hrs and you're looking at a $15-20K long block. I would love to live longer

[davekmoore]

I was once new to this forum too so this is not a criticism, but it might be good to do some searching on this forum and on google before your next post so you better understand some of the advice that's being given.

In particular, you've picked 195whp as your goal and seem to have ignored the probability that you need to strengthen the bottom end of the motor to make that power safely. This will mean a bunch of money in one go as is makes no point to do the rods one month and the pistons the next month. Trust me, saving up to do the bottom end in one go will also be waaaay cheaper than looking for high power without doing the bottom end (ask me how I know).

While you're saving up you would be well advised to find a local expert on these motors rather than someone with just general tuning knowledge.

[speed freak]

if you want to do it 'little by little' to spread the spending out why not buy all the required turbo parts little by little? You want power, turbo is the easiest and probably cheapest way to get power and safely if you do things right and have a good tuner. You could run boost as low as 6 psi or something like that and probably have more usable power and torque especially on the street for much cheaper then a proper n/a build. Plus built n/a motors usually wont have high tolerances as everything is maxed out (tune, compression, cams etc) to get the best possible power output. So they wont last anywhere near as long as a engine running low or even medium boost. Again I stress that as long as its a good safe tune running a boost pressure relevant to the engine internals.

Now Im not a mechanic or an expert Im just going off my general knowledge, experience and research. Just my 2c

[Magpie]

You will be disappointed by how expensive and slow a street ITB build will be, like, balls slow compared to a few grand turbo setup, which will be much nicer to drive.

Whilst Dann could be considered biased towards turbo, he is right in saying that a turbo is a cheaper and more reliable build. However I would have to say that the ITB's would be more responsive than the turbo build, at least low down. Or you could do a turbo/ITB build plenum and this would add to the cost.

If I get a chance I will PM you the specs of my build, however once it is finished MX5 Plus will be doing a post with all the specs of the build including dyno reports etc. My plan is to start a new garage thread and list all the mods before it goes on it's next journey once it has it's final tune.

As suggested do some more research as the road has been traveled by many before! Make sure you plan for an external oil pressure control (thanks wozzah), head wise you can choose from Wozzah, Gary Stewart or MX5 Plus (there are others) however there is only 1 MX5 Plus head at the moment

Block again you could go for 85 or 85.5mm pistons, but you would need to sonic test the block. If aiming for high RPM then you want as light as possible pistons/beams etc as well as valve train. Crank no need to lighten just make sure it is balanced etc. Main bearing support plate make sure you get the latest model as well as the sump to go with it. Also think about the Maruha baffle plate.

Think about protecting the engine with an accumulator, oil/water sensors that trigger if a threshold temp is exceeded (these are very cheap). And on and on and on ...