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> Ports on the old manifold are a bit rubbish, they aren't a particularly nice shape and I can't do much about it. The learning from the cylinder head is flow matters so there is a chance to improve performance with better shaped angled ports.
> I have potential projects I want to do that would involve this sort of aluminium construction so I want to make sure I can do it and put it through some abuse on my car first.
I've done the radius on the outside of the ports. Ended up using the radius cutter as much as I could then hand blending them. Looks fine, I'm happy with it. Would look better if CNCd but I'm not a CNC soo...
I gave one of the ports a run over with the die grinder, happy that the steps will come out easily. Will finalise the ports on the actual cylinder head.
Onto the next stage boxing in to the chargecooler. I'm going to tilt the supercharger / chargecooler over a bit to help out flow even more, centralising the ports over both chargecooler core outlets. Just need to check I don't run into any inlet tract vs valve cover issues from changing the angles, I don't really want to remake the sc inlet if I can help it.
I gave one of the ports a run over with the die grinder, happy that the steps will come out easily. Will finalise the ports on the actual cylinder head.
Ha ha they'll be smoother than that, but I'm not going to spend the time getting them to a mirror finish or anything. Maybe like an 80grit flap disk or something.
I've done the main welding of the manifold now. I need to add the bypass stuff but will sort that in a bit. I have tilted the supercharger / chargecooler on an angle, this was really about creating a bit more space to in front of the port on no4 as with the supercharger straight up it looked very tight for air to manoeuvre into that port. This is because the runners are longer than the old manifold, it has cost me space in the plenum area. So I will have to remake the intake but there we go. Generally happy, bit of bowing maninly on the lower side of the chargecooler mounting flange but nothing a skim on the mill can't solve. The new big 260A Tig I bought is awesome for this stuff, and the foot pedal really helped stop the sunken eyes at the ends of welds. All nice and bright, fairly happy with tidiness, could be a little better (more practice required) but I am very happy that I was getting right into the roots of the joints with the welds which is really what I wanted here.
Started work on the chargecooler rad. I cut the end tank off the old one and then couldn't weld it again because the material was just full of old coolant. I think the reason was the welding was rubbish (which it was) but in hindsight this is probably a part of the project I could do without.
Anyway, I picked up an aluminium radiator (I think its for a Corsa) for £50, and it is basically the perfect size. Issues with it requiring modifications are it has loads of fittings and brackets all over it that need removing and patching over. Also needs converting to double pass so I can have my pipework go in and out past one side of the coolant radiator like before. Big patch over where the inlet and a small fitting used to be. Cut a big V slot in the other end. One of the fill pieces has a bent flange on it that sits nicely in between the channels to block flow and convert it to double pass. It also cut out the old main outlet at the same time which was convenient. Still the remains of some brackets to grind down. Some of the various brackets fittings etc cut off so far
Been a little while since I posted, the enormity of the task ahead was looming large for the start of June for my alignment appointment.
I stripped down all the suspension and subframes. The mk2 subframes are in. I also made a Delrin / bronze bushing set for the arms of the car. The car previously ran PU bushings, replaced about 2.5years ago. Some corners of the car were very very stiff to move without the coilovers attached. A lot of stiction there. I also hadn't regreased them in that time so its on me too. Looking forward to seeing the difference the new bushings make to accuracy on track.
Its not finished yet but I did the metal work on the front of the car to hold the bonnet pins and support the radiators. I need to do the top part of the ducting but the concept is all there and worked out now. I little bit more metalwork and it will be sorted.
Then I rebuilt the engine. Piston 2 wall measured up fine at 3.5thou across all 4, 0.5 and 0.55mm top and bottom ring gaps respectively. This is the first bottom end rebuild I have done in the workshop and the extra space (and ability to keep the selected areas clean) was brilliant. Built up the head with the +1 intake valves. Compression is about 9.4CR, all chambers within about 0.2ml. Lobbed it back in the car with the head bolted down and ground the new intake shims on the lathe.
One calamity was that my mill speed controller broke. It is the control board, there was a big resistor that had broken a leg, one missing and another had gutted itself. Tried mending / replacing parts with no success, so I have had to order a new board which won't arrive for a couple of weeks. This means I can't do the final flatting operation on the manifold. I am going to run the engine in on the old supercharger manifold setup, and swap it out when I get the board. Hopefully by mid June when I have some events and shows. I have test fitted it in the car to check clearances, measure belt lengths etc. All looks good. It is tighter in places because the bottom outer corner of the supercharger is pushed wider, but its not a particular problem anywhere. Closest point is the oil drain but the perspective in the picture makes it look worse than it is - its atleast 20mm clear with that 45deg fitting, and I will run a 90deg fitting anyway to get a better hose angle which will give me more room. The engine mount setup really limits engine movement anyway.
So jobs left to do -
Bolt up all the suspension arms
Make new res tank
Finish ducting
Reinstall supercharger
Bit of hose and wire work
Bolt the bodywork back on
Get the engine started up
Car is all back up and running on the old supercharger manifold. First fire up was unproblematic, took it for a couple of drives and nothing dramatic happened, then did the first oil change.
I got the fibreglass wings painted and they came out fine, they also fit better than the aftermarket metal wings they are moulded from which is good.
It was a decent drive to get the car to the alignment shop, about 1.5hours. Good things are:
> The larger oil cooler mounted to the back of the radiator is working fine. Its fairly hot here at the moment and cruising temps are around 105 to 110degC, which is basically the same as before. Will see how it behaves on track but I feel fairly confident. I've noticed the oil runs cooler at motorway speeds now, and is actually hotter when stuck behind a slow car on a slower road. Makes sense as I guess the extra air speed helps ram the air through the coolers in front better so more cooler air gets to the oil cooler. This bodes well for track use and the higher speeds, and I'm very happy to now have it in a safe more protected position, but still with very direct simple oil hose routing.
> The bigger radiator fan is a beast and has absolutely no issue keeping temps under control in traffic, which is a great change over previous which on a hot day in traffic temps did get a bit hotter than i'd like.
> The delrin / bronze bushings are awesome. I haven't noticed any difference in NVH really, but over rough roads the ride is a lot less harsh, I guess from the reduced stiction. Very happy.
> The oil use has appeared to have stopped, and I haven't seen any tell tale puffs of smoke or more soot on the exhaust tip. Fingers crossed.
> I have had no coolant leaks whatso ever from any of my aluminium welded parts this time. I ended up doing a lot of welding on the new chargecooler radiator, and then also making a new reservoir / fill pot for it. I think the new welding machine can take the honours for this. The ability to separately set the end amps and the use of a footpedal to better control the end of the welds visually results in far less of a sunken end of the weld. Typically on my old machine you would come off the button, the arc would stop and the aluminium would continue to sink quite a lot, and you would get a little pin hole in the centre of this sunken part. I new this and despite my best efforts to manage it I could never reliably prevent it. The extra control on the new machine means I do not get basically any sinking of the end of the weld or the pinholes that accompany it, well happy.
Unfortunately I did find that the sync loss issue was still present which was extremely frustrating. I had made a new bracket to better align the sensor to the crank wheel and also wrap the sensor cable in farady tape (to try to prevent interference from the alternator. I had a bit of an idea when I got back home from the trip, switching the crank sensing in the tune from falling to rising edge. Since I made that change I have done quite a few test pulls, through multiple gears and it hasn't repeated the issue once. Before doing that every full throttle pull I had attempted I had had the issue. So I am hopeful its sorted. I have had issues like that on customer cars and it is usually one of the first things I try. Previously though my car didn't like rising edge. Bit odd but there we go, will continue to monitor.
I have got a bit of data from the +1 intake valves, but it is a little difficult to compare currently. It certainly hasn't lost me power, and I'd forgotten how hard the car pulls, it's great fun. Data wise it's a little hard to compare because the weather is so different now summer has arrived. Air temps are hotter, and we've had a mix of barometric pressures, which makes comparing fuelling difficult. But AFRs haven't moved in any noticeable way, and injector duties are within a couple of %, but with a weather reason to explain the difference. Nothing points towards any sort of major step change.
I haven't played with cam timings yet, maybe the larger valve will prefer a more retarded cam position as it should have greater flow at low lifts to make up for it, or perhaps the venturi in the port is now the limitation and needs opening up a little. Or maybe the current manifold is the limitation now and the new one will open things up. Will be good to try a few things. But anyway, I'm not massively bothered because it's good just to drive it again and seemingly have it working.
Need to chase up the part for the mill. I have a car show in two weeks, then a sprint after that. Then second weekend in July a trackday. At the very least I would like to test the new manifold at the July trackday. Would love to get the new manifold on the car for the car show but that might be a little tight timing wise. Anyway some pictures:
Back on its wheels See the new chargecooler res by the air box, and the new ducting setup (still needs some more rubber seals on it to fully seal) at the front of the car Oil cooler and fan on the back of the rad
Hi everyone, bit of an update. Car has been performing well, no further sync issues. Made it to the car show and back no issue at all other than a suicide pigeon trying to take out the chargecooler rad but no damage was done. Did take a couple of days to get all the feathers out the bumper mouth though.
I had the sprint day last Sunday, all went well. It was very hot but not a squeek out of the car, got me there and back no problem at all so very happy about that. No measurable oil use, no sync issues. I ran it on premium fuel but without the water injection. The water injection is still playing up a little bit, needs more attention, so I have switched off the map switching for now. Got another event in a week and a half which is an actual trackday. Going to try to get it all working for then. TBH I am going to do a few runs without WI and see if I can spot any differences in performance. I am quite tempted to remove the system, save the weight (around 20-25kg with a full water tank) and keep it simple on premium.
Did alright on the sprint day, 29th out of 91 and 5/9 in group. I was the 2nd quickest Mx5 there. The quickest was a turbo mk2 car in my group (300-350bhp), that also won our group. Fair play to Mike, the driver, he was about 3seconds quicker, plenty of inspiration there! The top 3 cars in the group were all very close in the mid 1:08 and I was running mid 1:11, only 0.2secs of 4th (a new Supra) which was a little frustrating. The first 3 runs before lunch I was making good progress shaving a second off each time, but then after lunch didn't carry on with that momentum, and I could see from other peoples times they seemed to be having similar problems.
The new soft tyres did really well, coming on strong after only a couple of corners, but the slightly more aggressive alignment and nb geometry has made the car a little more tailhappy than i'd like so it was a little difficult to fully commit to some corners. I've got a 22mm front ARB to load in the car, up from 19mm to see if this helps, then I can decrease rake and play with tyre pressures to fine tune. If this works I might look at making an rear in car adjustable rear bar and make a hollow front bar to take some of the weight out and have really easy on the fly balance adjustment. That would be pretty cool.
Really enjoyed the event though, great cars and really nice people just having a bit of friendly competition. I will definitely enter some more events next year.
I was going to be installing the new manifold in this time slot but I have other commitments and I don't want to rush all the bits I still have to do to support the manifold, like new inlet, new support. Also I am looking into having the manifold heat treated back to T6 - there is a local shop that looks like it can do this and it would take a lot of the nervousness out of the welded areas. So it will be going on before end of summer, likely in mid July but not right now.
Not sure what your spring rates are but if you haven't tried driving without a rear bar you should unhook it and give it a shot. My car was very twitchy especially lower speeds with rear hooked up, always had to undo it for autox.
Also I'm sure some aero would help but your car is so smooth/clean/simple, that I'm guessing you don't want to do terrible things like me and bolt a bunch of extra parts to the body.
They are 12.5kg/mm and 7kg/mm front / back. I was looking at trying disconnecting the rear bar, but I read the 949 alignment article Miata Race alignment info | 949 Racing and it recommended not doing that for road course use, due to the jacking effect. That's why I'm adjusting it at the front with the bigger bar. It doesn't need anything drastic just a little tweek.
Re aero, I'm not against it, and there are some big aero Miatas / Mx5s I really like the look of but my garage is at the top of a steep drive so id need to be able to detach any lip each time I get the car out. I just can't be bothered with that.
Also for instance Mike, the class winners car. It had a pretty small front lip / splitter a decent size rear wing but not ridiculous. So it's not like you have to have massive aero to be competitive (at the moment). As long as I can mix it up with the group and be in close competition I'm happy really. My starts were slow, that was probably costing me a second on the first straight, and I'm sure I could pick up a second or more with a little less tail happiness and the added confidence to push from the start that would give.
Had the trackday yesterday, went pretty well. I didn't take much video but I'll try and pick out a lap I didn't ***** up or get held up and post it.
It was quite a hot day, mid 20s (degC), oil temps were stable, but slightly higher than previously at 125degC-130degC. I'm alright with that, the oil I use is rated for continuous use at 125degC and intermittent up to 150degC. Didn't see any drop in oil pressure or anything, all seemed happy. So I'm going to call the new oil cooler setup a success.
The 22mm front arb worked really well, I found the balance a lot better. The car on a balance throttle naturally understeered, which then allowed me to trim that out with trail braking or throttle which felt a lot better than the car feeling nervous and always oversteering.
When I did get the car sliding though I was finding it a bit hard to correct, which is unusual. I normally find I can hold small angle slides, keep speed up and blend in the transition to grip at the end smoothly and it's relatively rare now I get into a slide that requires a proper save that slows the lap down. But I was making mistakes like that more often than not when getting into a slide that needed more than say 1/3 turn of lock to hold. I think it is the amount of caster I am running (9deg) which stems from having put offset bushings in the front and back of the front lower arm. It means that the self correction from the steering wheel is pretty vicious and forceful and catching it or turning it against that force to catch, hold or end the slides is either very difficult if going away from centre or hard to modulate if going in the direction of centre, and was totally mucking with any sort of finesse required to balance the car in a slide at high speed on sticky tyres. So I am going to try to do something about that before my next trackday at the end of August. 9deg of caster is too much for me with the depower rack and little weedy arms.
The soft tyres were also awesome, but they do wear noticably more than the mediums I ran last year, which is unlikely to surprise anyone. Realistically, I think I would get 2 or 3 at a push full day open pit lane big track trackdays out of them, but I am looking forward to the sprint style day at Curborough again which is next. I think I'll just have to weigh up the sort of days I'm going to do at the start of a season. I was running about 2secs quicker per lap yesterday than I have done before, which is cool, but not worth around double the tyre wear if I was doing a lot of uncompetitive open pit lane trackdays.
Hello again, bit of an update, hope everyone's having / had a good summer.
Had a bit of an issue with the supercharger. It developed an odd squealing sound. I was hoping it was tensioner pulleys or something like that but unfortunately it definitely sounded like it was coming from the rear of the supercharger. It was very intermittent at first, only coming in as revs dropped below 2000rpm, and only when the engine had been running 45mins +. Steadily got worse to coming in pretty much as soon as the engine was warmed up. Oddly it could be temporarily stopped by turning the engine off, then restarting straight away and it would go away for a bit. Anyway, long story short I sent it off for rebuild. It was a seal in the back of one of the rotors that instead of spinning on the shaft was spinning in the rotor. It has worn a bit of the coating / aluminium but luckily nothing life changing. Was very lucky though, last rebuild we swapped out the rear bearings to a sealed type - this saved the bearings from the aluminium dust that would have killed them, started rotor to rotor contact and destruction. Other small issues were discovered, mainly the front oil seals looked a little cooked and were leaking slightly. The grey paste on the rh rear rotor support used to be part of the internal rotor bore.
Basically, I am driving the supercharger very hard, particularly on a hot trackday, and the oil in the gear case is getting a bit hot. I've got some ideas that I will work on over winter. Currently my rebulder recommended 2year rebuilds for my current use, and I could plan that better if I say got it rebuilt next winter, so its fresh for the spring / summer season. From then on I can get it rebuilt every other winter as part of routine maintenance.
My rebuilder Pete worked a total miracle and got it back to me in about a week, so I managed to get over to Curborough again for a trackday. Loads of fun as usual, car ran absolutely perfectly. It was changeable in weather so there was a good mix of driving from fast dry to hilarious wet opposite lock action.
I've been busy / fixing the car over summer, and have a couple of events in September, but once they are done the new manifold will be making an appearance, along with a new chargecooler I have been making. I've been working on the design for a while now in the background but finally got to a solution I thought I could actually make properly. It is going to use the same Laminova cores my current cooler uses, but 3 of them rather than 2. I like the construction of the Laminova cores because they are a robust item that floats on o-rings at each end inside the housing, this in my mind reduces the risk of leaks over time due to vibration and movement. Downside is they are a certain round shape, that takes up a specific amount of room, so the space requirement takes quite a big jump each time you add a core. This has been one of the main difficulties in cramming 3 cores into the area, without increasing width too much, still being able to bolt up the supercharger (not growing height too much) and being strong enough support the supercharger.
Some pics of where I am currently. It's getting into the dangerous bit where I'm starting to weld it up. On the mill I've been working in hundreths of mm, for things like the o-ring seats and tube guides. As soon as you look at it with a TIG torch in your hand things move 0.5mm which is a bit of an alarming step change! I've been very carefully considering the order of welding and final machining to ensure things stay straight as possible, and important dimensions like the core holder tubes are on dimension and totally straight in the final product. Its always nerve racking with stuff as there is so many hours in machining on all these parts and I know it will be so easy to put a 2 or 3mm bow in it and at that point it would be game over, there isn't the meat in the important areas to correct that sort of deviation, and if there was, it would be heavier than it should be. Just need to get the process order right, but I've got a plan.
Cheers Ted, yep luckily not too much of a problem, missed an event but in the grand scheme of things not a catastrophe.
I'm interested to go back to the very original pulley ratio (2.19 vs 2.5) to see if I actually loose any power, would be an interesting test as originally pre intake and cyl head work it didn't make a difference
Chargecooler is coming along nicely. The housing is all one piece now, middle tube welded in then the air slots cut through. Drilled and tapped the housing for the end caps. Then onto the scary bit, welding in the side plates on the supercharger side, but it turned out to not be too bad. I made the fit up of the plates absolutely perfect, no gap anywhere at all, with deep bevelled edges. It took all 260A of my machine but I worked slowly and systematically and no disasters occured. Got the whole piece up to a reasonable temperature and just kept it there, taking 5min breaks in between each inch or so of weld. Took all evening but I'm very pleased with the result. Top and bottom surfaces have bowed about 0.5mm each end, if that, and the sides are less than that, right where I wanted it to be. The weld has penetrated right through in a few places and the rest you can see it is very almost through. I will put a slightly deeper bevel on it next time, just another mm and it will come all the way through everywhere, but I'm happy its properly in there. The side plates aren't structural to hold the supercharger but they do have to resist the sudden changes in pressure, from 200kpa to 15 then back to 200kpa within a second or so on gear changes. That is quite a bit of repeated force over that sort of area. Anyway, that is what R&D is for.
There is a bit of welding on the manifold side just the link tabs at either end that seal to the manifold, then remove the caps so I can tie the welds into the front and back faces. Then final machining to length and sizing of the core bores.
The cores themselves also arrived. Very happy with it so far.
It's all bolted together with the cores in! The line bore on the lathe worked great to size the core holders. Took two passes each tube but cut them spot on. Fit is nice and tight, but still easy enough to gently push the cores into place, like it should.
Few bits to tidy up but will be on to test fitting shortly
04-21-2023, 11:03 AM
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