mx5cartalk.com

Ok, i know nothing about cars and even less about well... everything else.

I've had my 1998 NB8a for years and years now, many of which has been spent just sitting idle and getting cranky at being abandoned. Did a few track days back in the day with the mx5 club and with SOTS at Wakefield, but things fell off (as they do) and the car was getting stroppy with the inconsistent attention and it all went to sh*t when i got a new set of V700s one of which leaked air and sent my track times to sh*t.. Life happens, car sits idle, and one day started serious hesitation between 2500-4500 rpm when cold and then would just hesitate on a narrow range. Various visits to mania and replacements of bits and pieces didn't seem to solve the issue and the car just fell to abandonment. In the little kms i put in, the engine sounded rough and agricultural, the lsd was way too harsh, the lack of power steering and air-con... the roof leaks and i couldn't find the right brand of sticky tape that i had been using to keep it together.. ugh... whatever... I used to REALLY like this car

Sometime in 2019-20 i would seriously consider selling it. In Sept 2021 i was seriously keen to move it on for say 5k but too lazy to put up an ad and put up with stupid questions so yet another year's rego went in...

I finally worked out the cause of the engine hesitation ... dodgy MAF sensor and the the car felt better. Engine didn't sound grumpy anymore and the throttle response and all that came back... Couple of decent runs up OPH and the engine hesitation was completely gone (provided the engine was not cold). Happy daze!

That said, hamx5ter is hamx5ter because his little legs just don't turn over quickly enough... this is a VERY gutless engine! My plan was to finally add some pace to the bling that a gold convertible suggests, but i do like my nat-asp rev happiness, burble, sublime throttle response and all that, so not keen on the FI path. Also 99% reliability please (because first line in post)

My cunning plan is get some cams (perhaps one of these two from Tighe Cams) but they will require an ECU (and someone to tune it).

https://tighecams.com.au/cars.htm

845C 57 17 23 51 254 254 226 226 .400" .400" H H Fast road.
725C 62 32 35 59 274 274 232 232 .400" .400" H H Non turbo competion.

Anyway, now that i've got hamx5ter working again, i did a motorkhana with the mx5 club on oct16 and my first trackday since 2018 or so at the new Marulan on the weekend. Went out as a first timer as i hadn't been there in years and the track and surface was changed. Rain, old tyres and all that, but I was VERY happy with the car and i didn't do nearly as badly as i thought i would after such a long break. Finished up at 1:05.29 i think which i thought wasn't so bad. There's probably 3 seconds or so to gain with tyres that are not 6 years old, with a dry track and a little more finesse in the driving.. Could NOT fault this car in any way at all!

I still have my ancient set of v700s (i'll take my inflator now and just pump up between sessions) and so if i got my money's worth out of these tyres I would have had enough seat time to to make returning to trackdays worth it.

That will also give me enough time to try and understand the cam / ecu thing... so putting it here for advise / guidance / training!

(come on down Stan!)

You're going to spend a bit for the privilege of a lumpy set of cams!

The answer to which ECU always starts with finding a tuner and using his preferred brand.

If you've worked with Mania before and will get them to tune, then you could probably go with a MegaSquirt PNP Pro, it's a bit cheaper than a Haltech, it'll plug straight in, Mania have tuned plenty of them, and it'll do everything you need.

Otherwise, Haltech is very popular here in Australia so finding a tuner for them isn't hard, but they do cost a decent chunk more money, and there are various levels of their Elite ECU, I'm not sure which is most appropriate so I won't speak to that.

A Haltech has the advantage of popular professional support, but you pay for it. MS has the price advantage, and grass-roots DIY support, but if you don't want to tune yourself you'll find professionals few and far between.

@bruce .. yeah i know turbo would be easy, but i'm not chasing any huge power. Just a little more zip while keeping basically the character of the car. It's not the lumpiness i've after, just a bit more zip (like me old clio3 wot i d/d which is just enough power to keep things funny). I'm not even after 200+hp... i reckon around 160hp would be perfect (and within my abilities to drive).

Thanks Lachy.. yeah i've been with Mania since the time i got the car, and they're always a good option but i'm just in the initial bits of figuring out what i want to do about getting a bit of extra power (I'm happy with basically everything else in the car, except for the removal of the a/c... doh!) so i'm happy to keep my options open.

I'm also happy to learn how to tune and i'm not in a hurry, so it might just be that i'll be happy to drive hamx5ter as is, get more seat time while i learn how to tune MS.

I had spoken to Dean Tighe many many many years ago and he had said an 805c would add power and keep the original ECU. Dropping in the camshaft would be easy, but he didn't say just how much power it would add.

You'll get more power out of simply adding an aftermarket ECU, with a tune. Increased timing and leaner fuel mixtures should give you a modest bump right out of the gate.

However, how far you can push it will depend on the health of your engine, and it sounds like she might be getting tired as it is. Best first get a check-up, get compression and leak down numbers and see if she'd do better with a refresh before chasing add-ons.

Tuning has a very, very steep learning curve and takes a long time to not only learn, but to apply the changes to get the results you want. And it comes with the risk that you'll kill the motor. I really don't recommend it unless you're super interested in it and have the time and patience for it.

cool... excellent advice I didn't think just an ECU and tune would make a significant difference.. wow..

hamx5ter wrote: i reckon around 160hp would be perfect (and within my abilities to drive).

Are you talking 160hp at the wheels or at the flywheel? I assume at the wheels, as only the poms talk at the flywheel..

Sorry to bust your bubble, but you wont get 160whp with just a set of cams and an ECU. More like 130whp.

(fwiw My NB8A did 133whp with intake/headers/exhaust/ECU/WHP cams on stock head/bottom end)

805Cs on the stock ecu would be lucky to get 15hp increase so you'd be looking more at 120whp best case.

If you actually want 160whp you'll need to spend up on headwork to make the most of the cams, and go more aggressive and rev it to get the power.
With the cams,ecu,headwork, the price would be multiple thousands, and you'll shorten its lifespan spinning it higher.

ManiacLachy wrote:You'll get more power out of simply adding an aftermarket ECU, with a tune. Increased timing and leaner fuel mixtures should give you a modest bump right out of the gate.

hamx5ter wrote:cool... excellent advice I didn't think just an ECU and tune would make a significant difference.. wow..

It wont make a significant difference, hence why ML added the word modest! Think single digit gains...

rascal wrote:

ManiacLachy wrote:You'll get more power out of simply adding an aftermarket ECU, with a tune. Increased timing and leaner fuel mixtures should give you a modest bump right out of the gate.

hamx5ter wrote:cool... excellent advice I didn't think just an ECU and tune would make a significant difference.. wow..

It wont make a significant difference, hence why ML added the word modest! Think single digit gains...

Thanks rascal, yes, modest. It won't be like strapping a turbo on, but it'll make the most of what you've got, and it'll enable you to make the most of whatever else you add, be it cams, exhaust or intake.

The head is the most restrictive part, so you'd definitely want to get it ported to make the most of any cams you pop in.

When you start adding up costs, you quickly realise why FI is favoured so heavily, it can't be beat on a hp/$ scale. If cost isn't the limiting factor and you love an naturally aspirated engine, then more power to you! But it is important to have realistic expectations.

BP4W head VVT bottom end NA6 chasis



all those cams are far too conservative

you want somewhere around 238-240 @0.50 or somewhere around 284 deg advertised duration
your 10.15mm lift is great mine are 10.2mm ( i think)

you want to mill your head within an inch of its life for extra compression.no discussions here. just do it. I had a VVT block & pistons so I'll have a bit more compression unless you put high compression pistons in yours.

get the bigger valves maybe consider lightweight valve train components for high revving. (if you w3ant to go there.) perhaps even redo all your valve guides. But tread carefully if the rest of your engine is tired....it will self destruct if the head is all new .

definitely port your head.I did the basic stuff

ditch the NB8A intake & find a square top. there is one on Gum-tree right now for $200. use your own throttle body.

Ive just upgraded from a MS2PnP to a MS3PnP. and its an awesome upgrade.

it runs so much better now cause I managed to understand more with cold start & idle

It still has some minor issues under 2000 rpm when cruising through car parks at almost no power
other than that the idle is a little lumpy. I could make it lumpier but its been such a joy to drive where i have it right now.


I rev out at 7500 at the moment. I can count the times Ive hit the rev limiter. but it goes there no problem. Doing the oil pump & ballancer is open to debate. Ive done almost 20K km in the last 12 months . engine feels strong. Ive also got forged rods under my bed. unsure if they will ever go in. if I manage to bend them I'll probably put them into the spare motor. but my torque levels are not high enough to warrant taking the engine out & fitting them cause then I'llk probably do a few other things


Ive got more in this engine , Im using the stock NB8A extractor so il eventually get the RB header

It uses a lot of fuel. in particular on E85.... but I haven't run it on E85 since the MS3 went in


youre welcome to come & drive mine. more for piece of mind abouty the sixze of the cams
yes its old school

but N/A is such a great place in the out of bounds School playground

head rebuild+ cams+ calibrating Cam followers ,cams , head gasket , head bolts, clutch adjustable cam gears , at least $3-5K

my cams

Ive also got a spare set of NB8A cams if you don't want to risk having yours reground. Mine are never going back in.

regrinding is much cheaper and also gets you around having to relieve the valve guides to fit a 10.15mm lift.

Im unsure what the maximum lift achievable is with a standard blank.

but keep that in mind.

and dont forget, USA horses are stronger on paper than ours . by around 13%

giggle .

yep, cheap broken cam gears on an interference engine ..... risky

Further on your ECU question, Haltech dont make an Elite plug n play option for NB8A. (even though their website suggests they do!) Its only the NB8B that they have it for.

To do an Elite on your NB8A you'll need a patch harness (or adaptor board) made up to suit. Boomslang in the states sell a ready to go one, but its $$$$ and you have to wait for couriers and be raped by customs/duty/exchange rates.
Making your own harness isnt rocket science, but also a bit of work if you arent that mech inclined, which your first sentence suggest you arent...

Just something else to be aware of when making your ecu choices..

This is great, and certainly a lot to think about.

I'm not really hung up on the 160hp... Just perhaps a good bump from the current output would be all I would really need. Perhaps the 130 to 150 is plenty.

FWIW, my car is currently set up as follows.
- Mania CAI
- Racing Beat headers 4-1
- SMB exhaust and Magnaflow muffler
- I have a straight pipe that's flanged and can be swapped out for the cat easily

I'll have to read all this through again slowly

I don't think it will be a question of just popping in a cam. I know the head will need tending to in the process too... and yes, I'll have to get the compression and stuff checked on this engine. I'm not confident of it. It's been sitting in old oil and coolant for 4 or 5 years and while it runs nicely, it's probably not the best base to spend money on...

@Stan... You're around in the inner west right? I'd love to check your car out... All I remember of P is all the different colours and the angry startup lump idle from many years ago...