Old school hottie build or forced induction?

[simie2014]

Hi folks. The short story...
Have a very nice White NBa, 2000 model. Original motor cracked a piston after some spirited driving.I pulled that out and replaced with low km motor bought online. it is running well and i am happy. So i have the old engine in the shed awaiting a rebuild perhaps? I have $5-6K to spend on an engine upgrade. I know that i can turbo or supercharge existing engine for a reliable 220 250 rwhp for that sort of money. (I think). But everyone is doing that.
How about a traditional old sckool rebuild of the dead engine into something with cams, steel crank, quality rods and pistons. Have that all balanced nicely. Port and polish the head, maybe bigger valves, set of quality extractors and exhaust will give 200 rwhp (i think). Any estimates on the cost of those mods to an Mx5 motor would be greatly appreciated. I am a bit handy (put replacement engine in car) so I am wondering how much is of this i could do myself.
I would be interested in particular anyone who has built or had built a strong, naturally aspirated NBa non vvt engine. Would love to know what you had done, the power it produced and perhaps even what it cost to do parts wise.

Any comments< opinions and advice will be appreciated. Cheers Simie

[speed]

Supercharged or turbo is definitely the best bang for for buck for higher hp numbers.
That said, at the end of the day they are just numbers.
Whats important is driveability and most important is your intended application. Ie street, track etc.
I personally have a turbo NA6 and although i really enjoy it, i went this path for budget reasons.
Your budget appears realistic for a N/A build.
I'd recommend you reach out to members such as magpie, OMGPham and STM.
They have differing setups which offers you a variety of opinions.
Stan the man has done a lot of DIY which will help you decide the effort and work required for porting and cams and if that is something you can take on yourself.
Regardless of what I have, I believe that a well sorted N/A setup is the perfect arrangement for a light weight car that is the mx5.
Good luck and I look forward to reading how you get on.

Steve.


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[bruce]

Whatever u want to do...

[StanTheMan]

im not sure I deserve to be mentioned in the same sentence as Mapie or OMGPham....im a hack.
weekend warrior at best.

i can say..... i enjoyed the Journey

[StanTheMan]

I need to also say

Speed is particularly talented in a lot ways. one of his many talents is getting cheap parts. he has the patience & vision very few of us posess.

for what you want.....while Speed may be able to get within your budget. the rest of is mere mortals would be paying twice as much at least.....

[3gress]

I couldn't resist jumping in and suggesting a high compression NA engine will get your neck hairs standing on end. Especially with individual throttle bodies in the mix to give a spine tingling induction roar, neck snapping throttle response and fits in with the 'horse and rider as one' build concept of the original mx5.
Not the most pragmatic path if H.P. numbers are the goal but will certainly make your smile muscles ache every time you drive it.
Look for a later model 10:1 compression stock block, add decent cams and complementary headwork, a decent aftermarket ecu to control it all and you will have all you need to be itching to drive it at every opportunity. Quite a few members have been down this path and could chime in with their opinions on the subject. Alternatively you could look toward madjaks intake manifold design that has the H.P. numbers to prove the worthiness. ITBs have an old school tuning feel about them, i constantly see the comparison between my own ITB BP NA mx5 build and a previous UC torana equipped with triple dellorto carbies.
No need for extensive ancillary plumbing of intercoolers and such, bery basic to setup and tune with only a throttle position switch, crank and cam sensor, air temp sensor and map sensor if volumetric efficiency is your preffered method of tuning.
I spent probably more than a turbo install but am more than happy with my engine and it's power output.
Cannot wait for the latest project to fire to life and sit at the traffic lights violently shaking to the lopy cams. Just my two bobs worth ..

[billybunter]

you could end up being a dark horse like the Dasun 2000 Sports was in its hay day - it was a pretty quick little sports car too

[simie2014]

Wow. Thanks for the comments. I will inwardly digest all that has been said. Thanks for the imput. I will have to contact Stan the Man for a chat. Thankyou Steve for your imput.
I live near the very into Mx5's Nitro Dan and his workshop. He has fabricated an induction system for the "little car" as we refer to it here. Here is an advocate for the turbo path and rightly so. Looking for something different however.

[speed]

You're welcome. STM, thanks for your comments.
I think cams and compression is a good start. Then either a skunk manifold or itb's as 3gress suggested.
You can do all this without dismantling the bottom end but obviously rods will still be stock. I'm not sure how many rpm the stock rods will handle but suspect you'd only need to go forged if shooting for high rpm. Maybe someone else with more experience can chime in?
I'm also guessing that stock pistons will be fine based on the fact that they handle forced induction. You could easy source another stock piston.
Then you'll need an ecu and injectors.
All of this would make a difference and go quite well.

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[StanTheMan]

so are there any more details on exactly what you want?

like are we talking an 8500 rpm screamer.
stock rpm with heaps of torque?
racetrack?
street?
is an LED in there as well?
engineering?
suspension upgrades in the current car?

[Magpie]

200 RWHP NA is a tall ask if staying with a BP motor and 1926cc. If you can get the right block you can go 85.5mm pistons and a Maruha crank get to 2.1 ltrs.

My engine will rev to 8,200 and has done over 8,000 track km so far with no engine issues. Torque kicks in from about 5,000 and is almost flat to soft cut at 8,200. The engine could make more power by upping the compression from 11:1 and changing the cams. However until I can get fast as it currently is no power upgrades.

The engine is very Streetable and easy to drive, comes into its own on the track BUT it is slow in a straight line.

If you are at Lakeside tomorrow it maybe possible to put you in the passenger seat of mine.

[simie2014]

I guess i am looking for reliabllity and efficency. Would like an engine that can handle high rpm but with plenty of low down talk (sounds likeni need a supercharger ) . The little car is not for the track racing but i do like a bit of spirited driving.. I figure insurance will not increase with it being non forced induction.

[StanTheMan]

ok get some high compression pistons
get an off the shelf cam grind.....unless you know something you like.or an expert can advise you on something specific. but for that.. ..yoy don't really need anything anything extra massive.....although youre then also need to go aftermarket ecu you may as well go a bit more wild. that's if you like poetry & Opera up high. but it all depends on your tune. your own or tuners ability.
with those kind of cams you will perhaps also need to upgrade your valve springs.
your basic port match will help. but don t expect it to move the earth.
all you need is a basic build......200 whp... you're better off taking Nitro Danns advice. $perHp

200 is going to cost a lot more than your budget
if you're a numbers man.....Turbo is always the better option.

my bp4W will probably be somewhere around 150-160...with cams238@050 bit of compression portmatch but its not about top numbers. it's about the added drama.....the opera & poetry
you would probably do a full reseal job...
probably re do valve seats. 3or 5 angle grind since your going to machining the block anyway.
vaves size depends on a lot ....and the rest of your beathing mods, do your research

I'm still confused about compression. while the community talks about shaving for compression....every machine shop & Builder rubbish it....they suggest piston for compression , another issue is finding shop who will machine 1.5mm off a head.

for what you say you want...its not necessary to touch your crank. you may want to use a 1.6 flywheel and clutch. although it wouldt hurt it if you do balance the rotating assembly.....but it's un neccecary unless you reving to the moon & back. money best spent elsewhere. like suspension & brakepad upgrade
the above will get you somewhere around the 4-5K mark. depending or not if you have your ECU tuned by a pro

I don't have experience with ITBs....ive got the mania intake. plenty of theatrics with that. unsure if you get the same decibel opera with Nitro Dans intake box. I'm unfamiliar his CAI box.

[rascal]

Would like an engine that can handle high rpm but with plenty of low down talk .

Realistically you are not going to get low down torque without forced induction of some sort. It is only a 1.8L 4cyl.
To get any sort of decent power out of a n/a BP without $$$$troker cranks, you'll end up needing to rev it high to get the power and probably sacrifice low rpm to get it. ie most of the gains with modded n/a BPs are at the top end..

fwiw, my cammed, ITB'd NB8A makes almost 50% more power at the top end than when it left the factory, but actually makes less torque down low than stock. Perfect for the racetrack, but a pain on the road, where you need lots of revs everywhere, otherwise Corollas are beating you off lights.

[speed]

Yeah 200 is pretty high for N/A.
Also reliability and efficiency is a tall ask.
To get reliability and power means you lose efficiency unless you go forced.
You could still go cams, compression, supercharged and e85 but you will run out of budget very quickly.
Then there is the supercharger vs turbo debate. I was supercharged before going turbo and although the SC was cool my turbo setup smacks it hard.


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