'97 Mk1 MX-5 V6 - Weights and Measures

[gryphon]

Mar 15, 2020 23:31:04 GMT trimtechniques said:

What a magnificent project. I also have a Dakar MX-5 and you have got my mind turning over what is possible. Mind you thinking about it and doing it are Two different things.
I admire your resolve and tenacity.

Thank you! I'll find out if it's worth it soon... 

Stock Dakars in good condition seem to be one of the more valuable mk1s for some reason. We're not doing anything that isn't reversible to that one, although a few choice upgrades can't hurt - Suspension is all done and the supercharger is still sitting in the garage.

Rocketeer kits are no longer being sold in kit form, you now have to go for the full turnkey conversion. I've no idea if they'll refine them a bit more and start offering kits again - currently the kit doesn't quite align with their ambitious sales pitch, but I'd have thought it was easier to tone down the sales pitch than actually supply a bolt on OEM quality conversion.

[cb11acd]

Mar 16, 2020 8:41:24 GMT gryphon said:

Rocketeer kits are no longer being sold in kit form, you now have to go for the full turnkey conversion. I've no idea if they'll refine them a bit more and start offering kits again - currently the kit doesn't quite align with their ambitious sales pitch, but I'd have thought it was easier to tone down the sales pitch than actually supply a bolt on OEM quality conversion.

I wonder what (or who) made them do that?? Maybe someone that questioned their wireing loom?

Can you wrap this up now. I am bored of waiting for a test ride in it

Also those new wheels look sooo much better, good choice.

[gryphon]

Mar 16, 2020 10:28:15 GMT cb11acd said:

I wonder what (or who) made them do that?? Maybe someone that questioned their wiring loom?

Can you wrap this up now. I am bored of waiting for a test ride in it

Also those new wheels look sooo much better, good choice.

There may have been some correlation there but I know I'm not the only complainer. I stand by their wiring harness not being particularly safe. I've actually already managed to prove that my fusing strategy works, partly due to a silly mistake on my part, partly because the wires have fallen out of two more of their crimps - which lead to my mistake of coiling a wire out of the way not very securely.

The good news is that instead of melting the wiring harness it just blew a fuse and stopped the engine. Fuses are good. Use fuses.

[MiataMark]

Nice wheels (OZ Superleggera) I'm assuming 15". I've got a set of original 14" Enkie (hollow spoke) that I keep meaning to get refurbed for daily use.

[gryphon]

Yeah 15", 14" don't clear the MK2.5 big brakes.

I can't quite say I like the look of the enkei hollow spokes, but they are very light! Especially with the smaller tyres... Get them on, I want to hear if you notice the difference

[MiataMark]

Mar 16, 2020 17:28:49 GMT gryphon said:

Yeah 15", 14" don't clear the MK2.5 big brakes.

I can't quite say I like the look of the enkei hollow spokes, but they are very light! Especially with the smaller tyres... Get them on, I want to hear if you notice the difference

I doubt very much if I'd be able to tell any difference, I would expect any difference due to weight would be outweighed by the difference in grip from smaller tyres anyway. One reason I'd like to put them back on is to lose some grip for day-to-day use.

Anyway they need a refurb' and new tyres before that, and decide what colour to paint them. Thanks for mentioning brakes though, I have put bigger brakes on (not MK2.5 big brakes) so should check that first.

[gryphon]

I think the weight difference should be felt in turn in, acceleration and braking due to the lower inertia as you're reducing the rotational mass rather than affecting the grip at the limits. Supposedly 1kg unsprung rotational mass is equivalent to ~3kg sprung mass in terms of the energy required for accel/decel.

Whether you or I would be able to truly tell the difference I have no idea

I think that 14"s fit around the 1.8 brakes...

[MiataMark]

BTW these are the wheels, I didn't post an image before because of problems with image problems

[gryphon]

Yep those are the ones. Quite sought after for autoX, according to a (possibly out of date) mx5 performance mods book I have...

My penny washers arrived to hold the polybushes in place - first thing I found was that the long bolt that holds the front top A arm steps down from 15mm to 12mm for the threaded section at the end, so the washers got suitably enlarged. I had hoped that it would be bolt out, washers in, bolt in, done. Since when were bushes that easy. It took quite a while, and eventually I managed it by pushing one of the bushes back into the A arm, giving me space to insert the washers, then using the bolt to pull everything back into place. Once I'd worked that out the other side went a lot quicker.

I definitely made life easier for myself by deciding I was going to do it in situ without removing anything to give better access or more room to manouver.....

Bush pushed out the way:

And all done:

Suspension sorted. All done for MOT!

Or not quite - what a surprise. My indicator stalk fixing/bodging has fixed the indicators, but now results in the high beams coming on along side the dipped beams. Oops.

The high beam switch sits perpendicular to the stalk and has a small 'middle' position where high beam is off. If it's pushed in either direction high beam comes on for flash (pull) or high beam (push) on the stalk. My previous bodge has resulted in the stalk sitting a little further forward than it used to, leaving the high beam on.

How do you fix a bad bodge? With another bodge of course:

Cable ties hold it nicely in place, allow the indicators to work and are actually quite secure. I've ordered a replacement already so this won't be in service for long!

That was Friday night, all ready for an MOT on Saturday (today) - But I called them this morning and they're full booked until Wednesday . I'd wrongly assumed that they would be pretty empty with everyone in lockdown.... Ah well, booked in for Wednesday, still a milestone!

[gryphon]

Well, like the rest of the world I've had some more time to do projecty things - just little tidying up bits so far though.

First off it's amazing the difference a bit of black plastic cleaner and tyre shine makes! Shame the rest of the car is covered in dust again from just sitting there...

Next area on the jobs list is interior. The ECU lives in the passengers footwell and up until now has just been sitting there in a mess of wires. There's a false floor panel that goes between the passengers feet and the bulkhead creating a little space for the ECU to sit. As there is no flat mounting point there (and I'd rather not be drilling holes in the bulkhead or floor) I decided to mount the ECU on the false floor plate - however it also isn't flat. It is also very difficult to attach the ECU to that, then plug it back into the wiring harness as there is simply no space! In what is probably going to be permanent temporary fix the ECU is mounted on some strips of NVH foam and held in place with a couple of cable ties. This allowed me to have the ECU loosely fit, plug it in, get the panel in place, then pull the ECU tight.

And it's looking all neat and tidy again! That panel has been out since I bought the car...

(I spent a loooong time polishing that sill guard... Had absolutely no luck hammering the dents out of it though)

Next up is the door cards - I was bought a set of black/red stitch quilted ones for christmas that have been waiting to go on. So, old door card off:

Two nice surprises! The membrane is in place and intact, and the speakers have had a little upgrade at some point to some kenwood units.

I had a little bit of audio investigation to do while I was here as there was a loud buzz coming from this door when music was playing. I had expected the speaker to be bad, but that's not it. If I knock on the door panel thought there's a very prominent rattle that took me ages to track down. Turns out it's coming from inside the winder bit of the window winding mechanism. I can't get that out without removing a lot more so unfortunately I left it for now.

Swapping the top bolster between the old and new door cards proved a very quick job and it all went together nicely! Now I need to work out what to do about speaker grilles.

These new cards are backed with a plastic foam sandwich material which is very light and certainly more waterproof than the old hardboard ones.

Definitely smartens up the interior a bit.

Next thing to work out is that the ECU doesn't seem to be switching the radiator fan on... the engine bay is prone to getting rather hot. Once it's hot it appears to continuously steam from the radiator. The last radiator did that, and now this new one does which is a little disappointing. I probably need to get it pressure tested. The odd bit is that I can hold my hand in the 'steam' and there's no hint of humidity, it doesn't smell... it doesn't feel like steam - just looks like the radiator is steaming!

[gtviva]

I like the door cards, very smart!

[ballbagbagins]

How fast will this be 0-60?

[gryphon]

Mar 31, 2020 15:58:19 GMT gtviva said:

I like the door cards, very smart!

Thank you - I agree! Rather pleased with them.

Mar 31, 2020 18:17:04 GMT ballbagbagins said:

How fast will this be 0-60?

I don't know to be honest. I'm guessing at 265Hp at the crank and total weight of ~1020Kg, so let's call it 1100kg including me. Put that into an online calculator estimator and it comes out around 4.4s. I'll have to test it at some point, but I think it's going to be quite traction limited - I've started to suspect I have a high ratio diff as it happily does 25mph in 5th at around 1300rpm (need to double check that). If I do have a 4.1:1 diff in there which is the highest ratio Torsen that Mazda made for them I'll probably be looking at replacing it with a 3.8 or 3.6 for lower cruising rpm. It's not as if its lacking low end torque.

[ballbagbagins]

That is going to be so much fun.

[gryphon]

Mar 31, 2020 21:31:02 GMT ballbagbagins said:

That is going to be so much fun.

It should be MX5's are great fun in stock form, so I'm hoping that this doesn't detract from the handling, just adds power and the soundtrack. Definitely won't be a momentum car any more though.

Had some more fun yesterday evening. I bled the coolant system as best I could, really not much air came out. As I was doing it I had a think about what I was trying to do and wanted a sanity check. Here is a picture of the coolant return from the engine with some 'helpful' arrows:

Hot coolant comes out of the top of the engine, into the thermostat housing (Red arrow) Yellow line is the thermostat, then into the radiator. When the thermostat is closed coolant goes down the purple arrow'd pipe, to the heater matrix then back to the waterpump/radiator outlet. This is why an extra hole or two was drilled in the thermostat because the sensors in the thermostat housing wouldn't have enough flow to get a good reading if the thermostat was closed... But I digress.

The sensors are pointing up at the moment as I was using them to bleed the system, they're now back at the bottom to ensure they are in the coolant.

Now taking a look at this all level:

The engine outlet and basically the whole thermostat housing are above the coolant level in the radiator. If I were to fully bleed the system, then open the radiator cap, the radiator should overflow? It definitely doesn't do that. To completely fill the system I'd have to fill the radiator cold. Run it up to temp, bleeding it to remove the top air bubble, then let it cool and suck in extra coolant from the expansion tank to replace the removed air?

Ideally the fill point would be the highest point in the system, but I can't raise the radiator as there's a bonnet in the way. For bleeding I was using the play in the silicone coolant hoses to lift the thermostat housing above the engine outlet then used the smaller sensor as a bleed screw. Feels a little flawed as it's currently set up but I'm not sure if it will actually cause issues.

The second item on last nights list was to investigate the oil pressure sensor that I fitted. I'd set up a little arduino based display as a temporary way for me to watch the oil pressure, and it was jumping around all over the place so I finally got round to cracking out the oscilloscope and taking a look at what the sensor was giving me, first with the engine off:

That graph shows about 1 seconds worth of signal at 1v per division (so peaks at about 1.7v)

The pressure transducer is a 5V device that is supposed to output 0.5v at 0PSI, 4.5V at 100PSI with a linear response in between. I've stepped the output down to 0-3.3v with some resisors so expec to see 0.33v to 3v instead, and with the engine off I had expected a nice flat line at 0.3v. Obviously not the case, no wonder my gauge was jumping around a bit!

Even with the gauge jumping around as it was, the 'average' value did seem to increase and decrease with what I'd expect oil pressure to be doing, so looked at the output agan with the engine running and revving:

Definitely a difference! The output is topping out at 3v, which is the maximum the sensor should be able to give me, and the average signal is definitely higher.

At this point I went and checked the pin out for the sensor to see if it was plugged in correctly. The sensor had came with a wired connector giving red, black and yellow wires. Diagrams online suggested that I might have the power and ground the wrong way around, which would mean that on the supplied connector Red was actually ground and Black was 5v... odd! Figuring that I probably need a new sensor anyway I reversed the polarity and promptly dragged my 5v supply (from a usb battery bank) down to <2v. Looks like I had it right in the first place - the problem with it being a cheap chinese sensor is there isn't alwas a defined pin out. Powered back up and no change in behaviour, so no (extra) damage done.

In summary, the output is definitely not what I was expecting to see, but does change in line with what oil pressure should be doing. The pulses occur at a similar frequency regardless of RPM, so I don't think I need to worry about that being a factor, I appear to have it wired up correctly. So I think I might have a dead sensor. I probably should have at least checked the 0psi output before putting the engine in the car, as it's rather inaccessible now! For the time being I should be able to use this with some filtering on the signal to at least determine if I have some oil pressure. Not something I want to rely on though.

The current sensor is one of these cheap chinese ones. Looks like I can get a honeywell branded one that may be better - although I didn't know they did anything automotive! Possibly I should go to an old school 12v one, but the port into the oil chamber that it's connected to was originally home to a much smaller oil pressure switch, and there isn't much room for a bulky sensor.

[gryphon]

When my engine was mis-timed and chucking neat fuel out of the exhaust the cat was getting pretty hot. Cherry red hot in fact. Neat fuel destroys cats but it wasn't worth doing anything until I knew it was dead.

Well, now I know it's dead. We had a good shot at getting it nice and hot before testing but no joy. At least I know that with the radiator fan on (with a jumper in the diagnostics connector, ECU still doesn't seem to be turning it on) the car can cope with sitting at around 3k rpm for 5+ minutes.

So now I've taken the cat off the car... I was expecting to see some internal damage, but other than being sooty it's all as it should be, no signs of clogging or damage.

So... Does the neat fuel actually denature the catalyst, or is it worth giving cleaning a shot before ordering a new one? Googling cat cleaning gives so much that looks like snake oil I'm not really sure where to start. Anyone had luck with cleaning cats in the past?

Back to google I go...

(No EricTheCarGuy, I don't really think I want to squirt a bottle of fairy through it)

Edit/PS: Rocketeer cars don't generally struggle on the emissions unless the cat is cold, which is why it's my prime suspect - and add to that the fact that it was glowing on a couple of occasions, I think this one is purely my fault!

[Rich]

Regarding your coolant pathway, the stock hosing on the Cherokee 4 litre puts the top radiator hose above the level of the cap. Admittedly the thermostat is below the level but one would think if you have added a few bleed holes in it it should be fine, after all, you have a water pump. I'd say the cat in question is probably past it now given it got red hot, but the fact the CO is high and the HC is fine is a tad odd. Have been following this thread on and off and a V6 will surely make the MX5 a pretty decent all rounder, I did always like the way the MX5 NA drove.

[kevins]

Cats should take neat fuel with no problems most performance cars pour it in at high load to cool the cat, what they don't like is heat, ultimately the brick will break up but before that the porous surface (at a microscopic level) glazes over, you lose a large part of the surface area and the reactive metals no longer convert efficiently.

I am afraid it looks like your cat has had it, while some of the potions may be able to clean contaminants off the surface they cannot reverse heat damage.

[vitesseefi]

I've seen youtube videos of people pressure washing them internally (hot tip, the cheaper, lower powered washers are better and less likely to blow holes through).

TBH, your numbers look more like running slightly rich to me. Do you have any exhaust leaks upstream of the O2 sensor that might be fooling it?

Re the cooling system, if it's not overheating it's probably full enough. You'll never get all the air out without a bleed point at the highest point, given the size of the pipe in question. Have a similar issue, though less extreme, with my Vitesse. The Thermostat is below water though. On my GT6 I have a modern (Golf) radiator and separate header tank mounted higher up on the bulkhead with air-bleed points at the top of the rad and thermostat housing piped back to the header tank. Seems to work just fine. Could you get the thermostat section to sit lower down? Do you even need to?

Nick

[gryphon]

Apr 3, 2020 18:23:07 GMT Rich said:

Regarding your coolant pathway, the stock hosing on the Cherokee 4 litre puts the top radiator hose above the level of the cap. Admittedly the thermostat is below the level but one would think if you have added a few bleed holes in it it should be fine, after all, you have a water pump. I'd say the cat in question is probably past it now given it got red hot, but the fact the CO is high and the HC is fine is a tad odd. Have been following this thread on and off and a V6 will surely make the MX5 a pretty decent all rounder, I did always like the way the MX5 NA drove.

Thanks, the coolant does seem to have stopped pushing past the expansion cap after the latest bleed, but the sensors (at least the gauge temp) seems to be reading low still so may not have much coolant there. I've ordered the kit to plug into the ECU so I'll have some more data soonish.
Cat wise I suspect you're right
First drive was very promising, desperately needs a full alignment though.

Apr 3, 2020 19:08:08 GMT kevins said:

Cats should take neat fuel with no problems most performance cars pour it in at high load to cool the cat, what they don't like is heat, ultimately the brick will break up but before that the porous surface (at a microscopic level) glazes over, you lose a large part of the surface area and the reactive metals no longer convert efficiently.

I am afraid it looks like your cat has had it, while some of the potions may be able to clean contaminants off the surface they cannot reverse heat damage.

Not what I wanted to hear, but kinda what I suspected. (In fact you may have said it might be dead earlier in this thread? I can't remember...) Interesting to know why the heat kills it though, thanks . How come the fuel used to cool it doesn't ignite in the cat (as I think mine did) and actually heat it?

Apr 3, 2020 19:40:40 GMT vitesseefi said:

I've seen youtube videos of people pressure washing them internally (hot tip, the cheaper, lower powered washers are better and less likely to blow holes through).

TBH, your numbers look more like running slightly rich to me. Do you have any exhaust leaks upstream of the O2 sensor that might be fooling it?

Re the cooling system, if it's not overheating it's probably full enough. You'll never get all the air out without a bleed point at the highest point, given the size of the pipe in question. Have a similar issue, though less extreme, with my Vitesse. The Thermostat is below water though. On my GT6 I have a modern (Golf) radiator and separate header tank mounted higher up on the bulkhead with air-bleed points at the top of the rad and thermostat housing piped back to the header tank. Seems to work just fine. Could you get the thermostat section to sit lower down? Do you even need to?

Nick

I was nearly a step ahead of you there... we have a cheap pressure washer. Or we did, until the high pressure hose snapped off the lance. It was a cheap one... (and very well used too)

No leaks that I'm aware of. Manifolds had new gaskets, the whole system is new and connections all seem good. As I said above I should be able to talk to the ECU soon, and as I have one O2 sensor per bank I can compare the two. If one has a leak one bank will be fuelling higher.

I can't get the thermostat lower without some extra piping, I've already twisted the join the the radiator to encourage the thermostat downwards. I think the thermostat is opening ok judging by rad temps, but the sensors next to it still appear to be reading cold - I will know more when I can get temps from the ECU.
For bleeding I had lifted the thermostat housing up so that it was virtually the highest point that I was bleeding from, but if I've bled it successfully it should now overflow if I open the rad cap which is annoying. I haven't tried that yet because I don't want to have to re-bleed it.

Thanks for the help, I'm off to find a replacement cat. Not sure I can change the thread title to "The cat is dead", that might be a little too misleading!