Which ECU?

[greenMachine]

Seconding first find your tuner, then find out his preferences for ECU. Budget is important obviously, but be realistic about the DIY route.

For reference re power, I made 125RWKw from a full race Gary Stewart engine on a safe tune on 98 using stock manifold (not IRTB). That's a bit over 160hp. That was at 7500rpm from memory, engine would run to 8 readily but for longevity I limited it to 7500 (shift lights set to 7500, rev limiter to 8000). Fast idle and lumpy as hell, car was mistaken by some in the paddock as rotary-engined such was the nature of the idle!! It would get very old very quickly in a street car.

The earlier dual-duty engine in the Greenmachine (c2006-2008) was around 115RWKw, pretty lumpy cams but quite streetable (probably 805c cams) That engine had extensive head work, decked block, extractors, etc.

At some point you will need SUBs, the bigger the cams and the higher the revs, the bigger the risk that a lobe spits a shim from the bucket. SUBs are a bugger to set up but once in and set up you can let your head go.

Just my 2c

[greenMachine]

Keep your eye out for second hand ecus, there is a degree of risk over their condition, but if you know what you want (or what your tuner wants), that can save you a lot. If you are using a tuner, they can check out one or may already know of/have a suitable unit.

Right now there is a Haltech E11v2 ecu in Toowoomba on the 'bay for $450. That is a superceded ecu, but was the top-of-the-line Haltech at the time. I ran the scaled down E8 in my racecar before it was killed and replaced by a PS1000, no complaints from me about its capabilities. The high end versions are specced for 12 cylinders, whereas we only want to use four. The Elite is still being sold by Haltech I believe (they have an integrated ecu/pdm Nexus as their current top shelf item), so the E11 is a few generations old (E8/11 -> Platinum Sport range -> Elite range). It will do pretty much everything you want it to, it just loses out in the bragging rights. Any established Haltech tuner would have no trouble working with one of these.

So there are options out there, and if you can save money for no loss of functionality, ...



PS - not recommending that E11 for you, because I have no idea about its condition/history, nor do I or you know what you want/need - it is just a convenient example of what it possible.

[hamx5ter]

Appreciate the great advice GM and the pointer to the Haltech is good. It should suit my purposes (probably should find a tuner first though). I don't have any idea of a Haltech tuner. Would be great if you could point me towards yours. Or did you tune it yourself?

I dream of IRTB but I'm being realistic 125kw would be plenty for me i think.

Also, found the squaretop intake STM was talking about. Msgd the guy. The intake sold a couple of days ago! doh!

He's parting out a NB8B though (and a supercharger kit! ... yeah... naah). It did make me think, would a VVT head / engine suit this better than my NB8A head? Still pretty leery about my engine, so WILL get it tested before i do anything else..

[StanTheMan]

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

Ionfident 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...

Those cams were the Thighe 935C on a 1.6. I was using an adaptronic

very different beast today but current cams are slightly more aggressive I enede up driving those 935C cams on the OEM ECU but it lost a lot of top end urgency. I couldnt get the Adaptronic to a drivable place just of cruising. No matter what I did.

modern ECU. feels much more drivable but is also a 1.8

[greenMachine]

Appreciate the great advice GM and the pointer to the Haltech is good. It should suit my purposes (probably should find a tuner first though). I don't have any idea of a Haltech tuner. Would be great if you could point me towards yours. Or did you tune it yourself?

Don't rush, that's the way mistakes are made. If you are going to use a tuner, do that first and take his advice is my advice.

The first tune on the E8 (dual duty, 115RWKw) was done by HaltechMatt before he joined Haltech as a techie. He was the gun, operating in Penrith so I travelled. The race engine came with a tune from Gary, but I had it maintained by Ed at Autotech Canberra, he has tuned/worked on many TA and rally turbo engines - sadly Autotech has closed and Ed has moved on. Very sad for me because he tuned the Autronic in my current car, that was a risk I recognised when I opted for the Autronic, and is a risk I now wish I hadn't taken.

I dream of IRTB but I'm being realistic 125kw would be plenty for me i think.

I think you would regret it, unless perhaps you were a committed track rat prepared to drive a registered race car. Assuming you could find someone to sign off on the rego inspection.

Also, found the squaretop intake STM was talking about. Msgd the guy. The intake sold a couple of days ago! doh!

Yes, keep chasing one.

He's parting out a NB8B though (and a supercharger kit! ... yeah... naah). It did make me think, would a VVT head / engine suit this better than my NB8A head? Still pretty leery about my engine, so WILL get it tested before i do anything else..

I wouldn't, but others would. There are some low/mid range gains to be had, but VVT is not trouble-free. Do your homework here so you make an informed decision.

AFAIK the heads flow the same, ie they are basically the same NB8A head.

I lurve a supercharger!! But I never would have one! We had a car up here that ran one (M62, maybe MP62?) for something like 250k kms trouble-free, was regularly hammered, eventually needed new bearings, then it all went to hell in a handbasket, even the Australian agents failed to repair it properly, so it reverted to stock, and the Autronic from that car is now in my SE!

Actually, I need to correct that, never say never! I would have a centrifugal blower. Setting up the belt drive requires care, but you have many of the turbo characteristics without the problems arising from the heat, though the big power remains turbo territory. Again, I know of a car down the south coast that has had one for a decade, maybe two, totally trouble free.

[hamx5ter]

That squaretop at $200 would seem a bargain. Skunk sell a similar one but it's 3 times this price. I would still prefer to have the Mazda squaretop anyway. I'll keep looking.

Noted about vvt / nb8a head.

I bought some coilpacks on the forum ages ago and a bracket to hold the thing. Gotta dig it up since the spark plug leads popped out at Marulan. Happily hamx5ter makes so little power that a missing cylinder makes little difference Flat out all the way through!

I've got to find a way to sort the dwel thing out though..

[plohl]

Only skimmed it above.... But just some quick feedback.

160whp is a sh*t engine to have on the road. That's full 2f race spec engine with all the head work and compression. All the overlap, will hardly drive under 2500 rpm.
Speaking from experience.

Knock about 30 hp off any of the US power figures and that'll be closer to what you see over here.

I recommend a link ecu over the haltech. The data logging is better, plus a few other things and they do a plug and play.
Not to say haltech is a bad option, I've run 3 of them in my car an they're capable. Haven't played with the new software on an elite yet though. Don't waste your time with megasquirt or adaptronic. Adaptronic is pretty much dead.

I ran tighe 805c's for a while in an otherwise standard engine - the adjustable cam gears are a must to make the most of them, would have to look at my notes to see what lift at tdc I ran them at. About 120whp.

Anything bigger and you need springs, head work etc to make the most of them. Cams are just one component of the airflow equation.

Putting a vvt engine in it is probably just as good as getting some bigger cams, without going crazy. Similar power as the 805c's and a better mid range for driving it around the street. If it's primarily a road car... I would recommend that.



And remember, turbos are trouble.

Sent from my Pixel 4a (5G) using Tapatalk

[Lokiel]

That's pretty harsh criticism of MegaSquirt Plohl.

Agreed that there are MUCH better options than MS2 and Adaptronic ("swallowed" by Haltech) but MS3 is very capable and there's lots of online support available - finding a MS3 tuner is the biggest problem.

Were your comments specific to MS2?
If not, please elaborate; as someone who's actually used multiple ECU brands your thoughts are appreciated.

[plohl]

It wasn't really harsh... more to the point.

The biggest turn off for me with the megasquirt is a mate nuking an extremely expensive IPRA engine build due to multiple injector driver failures. That was an MS3Pro - I had recommended the ECU, though at the time, the build was a lot more sedate, as it seemed to pretty good bang for buck. It wasn't being tuned by an amateur either. The MS3Pro had been on the market for about a year IIRC. With the dollar dropping, the MS3 Pro lost it's bang for buck status over the more local options - for a 4 cylinder anyway. I'm not sure what pricing is like now.
If you're not building it yourself as a bit of a project, or planning to tune it yourself, I think you're better off spending the money on something you can get tuned locally and reliably.

As for the adaptronic - the 440d was a big step up at the time from an MS2, and the functionality it had was better in some respects to the haltech PS series, though the software was a bit meh. Andy provided great technical support - maybe it was a case of the business growing too quickly or something, but software bugs started to pop up, and when you spend multiple weekends trying to get a car running, scope pretty much everything only to figure out there was a software bug and if you'd just tried old Wari a month ago... kinda leaves a sour taste. Plus it doesn't really exist anymore...

[hamx5ter]

Thanks Plohl... good advice again. Looks like i'll have to do quite a bit more reading to get a better idea of what's actually workable for an nat-asp mx5 BP.

The car's mainly a weekend / track car. It'll be registered and has to be reasonably driveable in public spaces so that i don't have the police asking me questions. I'm not concerned with driveability as much as reliability. There's always lots of people at a trackday in highly strung cars (there were a couple on Sunday) and they have to back off or cut short their day because the car is playing up. Not something i would even be able to diagnose and fix on the day.

I didn't realise there was such a power difference (or maybe the 805cs don't add much to the NB8A?) between the NB8A and VVT heads... I don't even know how much power my car is supposed to make, but it doesn't seem to do so badly against most other NB (and some NCs), so :scratches head:

I guess the general consensus is not to worry about the hardware but look for a tuner and take it from there... I've started reading about the Link ECU (they're kinda local! just across the dutch!) and it seems it will be the Haltech / Link. The link is attractive to me because there seems to be a plug and play option (MX5Link - MX5NB1X). Also apparently the Link ECUs are sold via dealers and they dealers can install and dyno the car which makes it a more turnkey thing (kind of) for a non-spanner-monkey like me...

That said, GM's suggestion of a second hand ECU (the Haltech E11 for $450 on ebay) seems pretty attractive It just comes to finding the tuner and dyno for the Haltech.

For now, i'll get on with replacing the two control arm bushes that are pretty worn, get the engine compression tested, do some general reading on tuning and start looking for a reputable tuner.

[StanTheMan]

come & drive mine . youve goot my phone number. Its close to the 160 rwhp.

its super reliable . its a daily driver.

it is very mildly mannered in traffic now. That all depends on the tune. it was a handfull to drive in traffic until recently

most race-cars are not tuned for that.I self tuned my car. it never ends. Its taken me some time to get to this point.

look at the 935C option it is a little more aggressive than the 805
stick with your BP-4W head. your're not going turbo. less cam choices available . Ive also read when cams get too aggressive the VVT becomes unmanageable. I don't know the full truth there yet.

and no I don't believe that the VVT will maker up for aggressive cams. not even for a second.
You can also set your Cam sprockets so it becomes more drivable . But at the racetrack maybe retard the exit ( or both)a bit for extra scavenging . It will take all of 10 min for your prep.

Idle might go off a little but. but you can also have 2 maps for that purpose.

[hamx5ter]

Sounds good... GREAT actually... I'll read up a little more on this for a bit, get some hamx5ter time and hit you up in a couple of weeks for a test drive. A daily drive NA with 160rwhp sounds amazing.

In the meanwhile, i've started reading Trav's Race Build... I don't know how the story ends! I'm hoping it's a happy ending!

[StillIC]

...

160whp is a sh*t engine to have on the road. That's full 2f race spec engine with all the head work and compression. All the overlap, will hardly drive under 2500 rpm.
Speaking from experience.

...

I have a ~160whp 1.6 road/race engine (built for NSW Supersprints) which pulls fairly cleanly from an idle of about 1100 rpm. Not much grunt under 2000rpm but by 3000rpm it's on. I aim to keep revs above 2000 when driving around town but is driveable below that. Power curve sits a few kW lower than STM's through the mid-range but ~matches his peak with greater rev range (built for 8300).

I have a 280 intake and 272 exhaust and a very wide LCA (lobe centre angle) of 116 or 117 deg. This reduces the overlap, but needs a highish compression ratio, or more correctly expansion ratio, to work well. Mine is 11.7 to 11.8:1, depending on the cylinder and how accurate I was with the syringe and clear acrylic. Built to rev to 8000 rpm, hard limiter at 8300. Cost a heap to build.; too scared to add it up. It runs on an old Adaptronic from ~2008. I'd rather something more modern these days.

When I first built this engine, it wasn't too happy below 2500 rpm but I recently (2 years ago?) added a CAI built to Emilio's length/diameter specs which gave it a better bottom end! I was expecting the shorter system to reduce bottom end and increase top, but it feels like the top hasn't changed and the bottom is better (ooh ahh!). It is fine on the road (although the loud free flowing exhaust can get tiresome); not even hill starts worry me.

[CrazyRacer]

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.

I went different path and cut off the factory ECU plugs and repinned the loom for the Haltech AMP plugs.

I have all the wire colours to Haltech pins mapped out in a spreadsheet if you want to go this way.

NB8A to Haltech Elite 1500 Wiring Mapping

You'll see a few comments about repurposing a couple of wires as I was putting a VVT into a NB8A and needed some wires to control the VVT valve.

On camshafts Maruha do a good selection of race cams including a 264 for the VVT and a bigger selection for the BP4W. I just had some arrive from Japan, but won't get them in an engine till next year so I can't tell you what they're like yet. Their cams are a bit pricey, but they are billet and can be a little cheaper if ordered strait from Maruha. Saiji from Maruha is great to deal with via email.

But if you go anything other than very mild street cams it gets expensive as you're going to need Shim Under Bucket lifters and better valve springs to run them, porting and compression to get the most out of them then some supporting mods for reliability and longevity at the higher revs you'll need to make more power.

[plohl]

....
stick with your BP-4W head. your're not going turbo. less cam choices available . Ive also read when cams get too aggressive the VVT becomes unmanageable. I don't know the full truth there yet....

Once you increase lift and duration, you'll have to mechanically limit the amount of swing you have with the VVT - else you'll mash stuff together.
I know Gary Stewart has done that on a engines - I think it halves, from ~40* to ~20* variation, with 10 or 10.5mm lift cams. I can't remember what duration they were, the heads had a decent amount of work on them too. I'm rebuilding a vvt engine for a mate at the moment and unless we were going to put 20hours or more headwork into it, plus SUB, bigger springs etc etc, Gary said don't bother with bigger cams.

....
and no I don't believe that the VVT will maker up for aggressive cams. not even for a second.
You can also set your Cam sprockets so it becomes more drivable . But at the racetrack maybe retard the exit ( or both)a bit for extra scavenging . It will take all of 10 min for your prep.

Idle might go off a little but. but you can also have 2 maps for that purpose.

I'm looking at a more bang for your buck and considering the law of diminishing returns.
Considering Cams ($1000 ish), good cam gears ($500), some headwork to make the most of your fancy new cams (10-15hrs @ 100/hr), Springs ($500)... $3000ish*
That's before you've got it tuned... or considered the fact you're slapping the head on to a tired old bottom end, need to up the compression to make the most of the head work and cams. So you dial it back, get the smaller cams, only get the head essentially cleaned.

The vvt cams aren't much smaller than the 805s and I made about maybe 4-10 less peak HP than the 805c (actually, it was 805c and a vvt exhaust cam at the time as my 805c exhaust cam had a crack ), but the vvt engine definitely had more area under the curve. Lap times weren't noticeably different either once you factor in tyres, and the fact I only have the vvt engine for a month).
I'll see if I can find the old runs at Gary's when I am next there.

I would recommend new springs for a vvt engine if you did get one - 949 racing recommend it, Gary recommended it, and it's cheap insurance against spitting a shim. I think the set I put in a mate's head recently were about $300.

*all prices are ball park for new parts. Might get stuff cheaper... might not

....

Intake makes a big difference. I posted this a while ago now. https://mx5cartalk.com/forum/viewtopic.php?f=29&t=78696&p=956225#p956225

I can't remember what the LCA is at the moment, but the less overlap will help with drivability. I think I have double the lift at TDC on the intake with the current cams than the 805c's, so 4mm vs ~2mm if I remember correctly. I generally shift between 7.2 and 7.5k. Only rev a bit for certain corners so I don't have to shift just before getting on the brakes. Current engine is about 11.8:1 (measured with every together). Cams are 10mm lift, 250* @ 50thou. It's one of the 2 mx5plus heads - Magpie has the other one. Even Gary thinks it's the best head he's seen with respect to craftmanship etc - although, his 2F heads flow more... and his engines make more power still

That said, GM's suggestion of a second hand ECU (the Haltech E11 for $450 on ebay) seems pretty attractive It just comes to finding the tuner and dyno for the Haltech.

Seriously, better off just saving for longer and buying a modern ecu or even consider a megasquirt...
yes, heaps of people can still tune them, but you're running into problems even just getting the software to run on new computers.

For now, i'll get on with replacing the two control arm bushes that are pretty worn, get the engine compression tested, do some general reading on tuning and start looking for a reputable tuner.

No point spending money on a flogged bottom end. A mate did this circa 2012/13... After putting in another engine which was also a dud, he's now got a smokey (valve stem seals) vvt engine and we're rebuilding another on the side. If he wants more power after the refreshed engine goes in, we've agreed he should just get an 86.