Mazda MX6 2.5 V6 manual
Discussion
I'm working on the new intake setup for the MAF and IAT sensors. I bought a cheap intake pipe kit from ebay that has the aluminium pipes and air filter I need. Since the MAF is a 3" internal diameter the intake is going to be 3" straight through to the throttle body, where is necks down to 2.75".
Mounted up the Xedos 9 ECU, slots straight in.
An illustration of how restrictive the standard VAF is compared to the MAF. The pic' shows the vane fully depressed, so the incoming air has to overcome the resistance of the vane spring as well necking of the air path. This mod' is has been dyno tested and is reported worth around 10bhp on a standard NA motor.
New four wire lambda sensors.
MAF is as clean as a whistle now after a going over with MAF cleaning spray.
A trial fit of the intake, the position of air filter is much better being further away from the exhaust manifold. I need to cut down the couplers as they are excessively long, buy some more jubilee clips, and mount the IAT sensor in the 45deg pipe behind the filter.
Mounted up the Xedos 9 ECU, slots straight in.
An illustration of how restrictive the standard VAF is compared to the MAF. The pic' shows the vane fully depressed, so the incoming air has to overcome the resistance of the vane spring as well necking of the air path. This mod' is has been dyno tested and is reported worth around 10bhp on a standard NA motor.
New four wire lambda sensors.
MAF is as clean as a whistle now after a going over with MAF cleaning spray.
A trial fit of the intake, the position of air filter is much better being further away from the exhaust manifold. I need to cut down the couplers as they are excessively long, buy some more jubilee clips, and mount the IAT sensor in the 45deg pipe behind the filter.
Edited by MX6 on Wednesday 19th September 13:52
Edited by MX6 on Wednesday 28th November 13:42
Not a lot of progress really because holiday season, but I just felt like doing a little update...
I'm still waiting for the turbo manifold/downpipes that are on the boat over from Canada, I've decided to just go straight for it and proceed with the turbo conversion when they arrive. They the the heart of the set-up really and dictate the other parts needed, which I have slowly started buying up. It's very much a budget build so I've been waiting to find things for cheap.
So I've been planning the set-up. I've already procured an ebay T3/T4 turbo to mount to the T3 flange on the pipes. I will get a Greddy knock-off 38m blow-off valve and 2.5" dia pipe with the correct flange, plus I'll be using a 38mm Tial knock-off external wastegate with a 5-8psi spring to control boost. This will vent to atmosphere via a 38mm so called screamer pipe, I found one unused secondhand for £9.45 delivered so bought that.
I've been experimenting with using the Xedos 9 ECU and MAF to control fueling but that doesn't appear to work correctly so I'm now planning to use a VAF to MAF converter board with the standard ECU to control fueling correctly (ie. run at stoich 14.7 AFR) for idle and cruise, and use a 12:1 FMU fuel pressure regulator to up fueling so it is rich under boost. So I can get enough fuel in for any decent amounts of boost I will need bigger injectors, and the only direct fit option for the MX6 are those from a Millenia S (basically a US market Xedos 9 2.3 miller cycle supercharged, rare car). I finally managed to buy a used set of 6 from the States for £65.46 delivered, still waiting on those as well. They are red top as opposed to blue but are otherwise physically the same, they are around 310cc compared to around 220cc for the standard MX6 injectors.
I've mounted the AFR gauge in the din gauge panel, having fab'ed up some little brakets to secure it. I've ordered a similar looking boost and oil pressure gauge to fill the two other holes.
I bought another new driveshaft for the nearside for £26.94 delivered to match the new one I fitted t'other side. The CV boots look knackered but haven't started leaking yet.
In other news I got a long postive battery cable so relocate the battery to the boot, to make way for turbo gubbins, so I've started working on that...
I'm still waiting for the turbo manifold/downpipes that are on the boat over from Canada, I've decided to just go straight for it and proceed with the turbo conversion when they arrive. They the the heart of the set-up really and dictate the other parts needed, which I have slowly started buying up. It's very much a budget build so I've been waiting to find things for cheap.
So I've been planning the set-up. I've already procured an ebay T3/T4 turbo to mount to the T3 flange on the pipes. I will get a Greddy knock-off 38m blow-off valve and 2.5" dia pipe with the correct flange, plus I'll be using a 38mm Tial knock-off external wastegate with a 5-8psi spring to control boost. This will vent to atmosphere via a 38mm so called screamer pipe, I found one unused secondhand for £9.45 delivered so bought that.
I've been experimenting with using the Xedos 9 ECU and MAF to control fueling but that doesn't appear to work correctly so I'm now planning to use a VAF to MAF converter board with the standard ECU to control fueling correctly (ie. run at stoich 14.7 AFR) for idle and cruise, and use a 12:1 FMU fuel pressure regulator to up fueling so it is rich under boost. So I can get enough fuel in for any decent amounts of boost I will need bigger injectors, and the only direct fit option for the MX6 are those from a Millenia S (basically a US market Xedos 9 2.3 miller cycle supercharged, rare car). I finally managed to buy a used set of 6 from the States for £65.46 delivered, still waiting on those as well. They are red top as opposed to blue but are otherwise physically the same, they are around 310cc compared to around 220cc for the standard MX6 injectors.
I've mounted the AFR gauge in the din gauge panel, having fab'ed up some little brakets to secure it. I've ordered a similar looking boost and oil pressure gauge to fill the two other holes.
I bought another new driveshaft for the nearside for £26.94 delivered to match the new one I fitted t'other side. The CV boots look knackered but haven't started leaking yet.
In other news I got a long postive battery cable so relocate the battery to the boot, to make way for turbo gubbins, so I've started working on that...
Edited by MX6 on Wednesday 19th September 13:55
So my turbo exhaust pipes finally turned up today, after taking over a month to arrive on the boat from Canada. I had a bit of a muck about with them last night, did a quick trial assembly so I could have a look see and work out what gaskets and fixing hardware I will need for the installation. The outlet from each manifold is 2" and the pipe that mates with the cat is 2.5".
Although I've seen several differing setups including twin turbos, this is pretty much the standard layout for the MX6 (and with other transverse V6's cars as well) with the turbo mounted high on the right side of the engine.
I'm enjoying the nice shiny look, looking forward to replacing the scabby manifolds and downpipe on the car with these. I'm planning on cleaning up the oil and rust under the front of the car when I fit these, I hope to work on it next week.
There's a few more bits and pieces I still need to buy for the turbo build. I recently bought an ebay 38mm external wastegate and a boost gauge. Parts I still need: intercooler, 2.5" intercooler piping, blow-off valve, catch-can, uprated fuel pump, 12:1 FMU, VAF-to-MAF converter.
Although I've seen several differing setups including twin turbos, this is pretty much the standard layout for the MX6 (and with other transverse V6's cars as well) with the turbo mounted high on the right side of the engine.
I'm enjoying the nice shiny look, looking forward to replacing the scabby manifolds and downpipe on the car with these. I'm planning on cleaning up the oil and rust under the front of the car when I fit these, I hope to work on it next week.
There's a few more bits and pieces I still need to buy for the turbo build. I recently bought an ebay 38mm external wastegate and a boost gauge. Parts I still need: intercooler, 2.5" intercooler piping, blow-off valve, catch-can, uprated fuel pump, 12:1 FMU, VAF-to-MAF converter.
I thought I'd wait longer until there was a bit more progress to do an update, not sure if I'm just talking to myself but are some details of what I've been up to with this, going to gloss over the nitty gritty...
Pulled the front end off the car to get better access.
Got most of the hardware and gaskets together.
I dragged off the old exhaust in one lump - both manifolds, downpipe and cat.
Trial fitted the new turbo and exhaust to check fitment and see what's what.
Cleaned and wired brushed the frame and various parts, then lashed some paint on.
Pulled the front end off the car to get better access.
Got most of the hardware and gaskets together.
I dragged off the old exhaust in one lump - both manifolds, downpipe and cat.
Trial fitted the new turbo and exhaust to check fitment and see what's what.
Cleaned and wired brushed the frame and various parts, then lashed some paint on.
Decided on a same-side front mount intercooler and 2.25" charge pipes so got those bought, had a little play around to figure out how I'm going to route things.
Making DIY polyurethane engine mounts.
Wire brushed the frame in the frontal area, there was quite a bit of surface rust but all solid, no holes thankfully.
Bought an ebay Tial knock-off external wastegate, came with an 8-11psi spring so replaced it with a 3.63psi Tial spring, I want to start off on low boost then dial it up if everything is looking good and working correctly.
Refurbed stuff, new hardware, etc.
Making DIY polyurethane engine mounts.
Wire brushed the frame in the frontal area, there was quite a bit of surface rust but all solid, no holes thankfully.
Bought an ebay Tial knock-off external wastegate, came with an 8-11psi spring so replaced it with a 3.63psi Tial spring, I want to start off on low boost then dial it up if everything is looking good and working correctly.
Refurbed stuff, new hardware, etc.
Did some recent work on the turbo oil system. The high pressure 4AN feed line is fed from a sandwich plate on the oil filter.
Fitted up a 10AN bung in the sump pan for the drain line.
Had three sump pan bolt heads snap off! Drill and tapped some new M6 holes, plus used a knife to clean off all the old silicone sealant from the sump pan and block.
In non-turbo related news, I fitted the front lip to the bumper and trial fitted it back on for a look.
Bought some new wheels, spent a while trying to find a set I liked with my prefered sizes. Volk GTP's, two piece split rims, staggered with 17x8 fronts and 17x9 rears, et45 offset all round. They aren't in good shape, need a refurb and have rubbish tyres. On the plus side they hold air, are round, and very cheap!
Fitted up a 10AN bung in the sump pan for the drain line.
Had three sump pan bolt heads snap off! Drill and tapped some new M6 holes, plus used a knife to clean off all the old silicone sealant from the sump pan and block.
In non-turbo related news, I fitted the front lip to the bumper and trial fitted it back on for a look.
Bought some new wheels, spent a while trying to find a set I liked with my prefered sizes. Volk GTP's, two piece split rims, staggered with 17x8 fronts and 17x9 rears, et45 offset all round. They aren't in good shape, need a refurb and have rubbish tyres. On the plus side they hold air, are round, and very cheap!
Edited by MX6 on Wednesday 28th November 14:52
Hi Cookeh, good to know thanks for the reply. 
The spokes are actually in a dark grey at the moment but I was thinking of doing something different with them. I do like the idea of a dark bronze as you suggest, I've seen that on various BBS split rims and think it's a striking look. I do really like the polished lip look too, I had some single piece BBS rims with a diamond cut lip on my previous project car. I've been having some thoughts about going black though I have to confess, with polished bolts. Seems to be quite a fashionable style, it does look aggressive... Not too sure yet though.
Edited to add - saw these recently on this Probe, I'm quite taken with this colour scheme, bronze lips/drums, satin black spokes.
The spokes are actually in a dark grey at the moment but I was thinking of doing something different with them. I do like the idea of a dark bronze as you suggest, I've seen that on various BBS split rims and think it's a striking look. I do really like the polished lip look too, I had some single piece BBS rims with a diamond cut lip on my previous project car. I've been having some thoughts about going black though I have to confess, with polished bolts. Seems to be quite a fashionable style, it does look aggressive... Not too sure yet though.
Edited to add - saw these recently on this Probe, I'm quite taken with this colour scheme, bronze lips/drums, satin black spokes.
Edited by MX6 on Wednesday 28th November 17:21
The Probe is actually a UK car, but I take your point about losing the detail of the spokes with a dark colour, and especially black. I do quite like the idea of painted lips though. On the diamond cut wheels I had before the mirror finish was hard to keep in good condition, either a lot of polishing or you have to laquer them which doesn't always last that well. Plus a practical consideration is that theses new wheels have some curbing on them, so I can see it being easier to restore them with paint rather than getting them into good enough shape to be polished again.
MX6 said:
The Probe is actually a UK car, but I take your point about losing the detail of the spokes with a dark colour, and especially black. I do quite like the idea of painted lips though. On the diamond cut wheels I had before the mirror finish was hard to keep in good condition, either a lot of polishing or you have to laquer them which doesn't always last that well. Plus a practical consideration is that theses new wheels have some curbing on them, so I can see it being easier to restore them with paint rather than getting them into good enough shape to be polished again.
Wow, wish I saw some weather like that where I am! I will admit I really do rather like the painted lips on that Probe, and you are quite right that it will be significantly easier to maintain and/or repair.Cookeh said:
Wow, wish I saw some weather like that where I am! I will admit I really do rather like the painted lips on that Probe, and you are quite right that it will be significantly easier to maintain and/or repair.
Yeah me too, it's pretty dark and wet here, I'm guessing those pic's must have been taking in the summer. I'm still thinking on the wheel colour and looking at pic's online, but I don't need to decide on anything at the moment I guess. I trial fitted the wheels and they look to be a pretty much perfect fit, they clear the struts and come almost flush with the arches (I have 5mm spaces on with the RX7 wheels for clearance due to the higher offset, so could get rid of those).
The rears have a significant stretch on the tyres, they are 215/45R17 on a 9" wide rim! I'm thinking of going for a 245/45R17, those would fill the arches better. The fronts are running 225/45R17 on a 8" rim which is probably what I'd stick with.
seiben said:
Well this escalated! 
Looking forward to seeing how this progresses. Keep the updates coming
Ha, yes it has escalated that's for sure! I should have just fixed the car and enjoyed it for what it is, but here we are. Looking forward to seeing how this progresses. Keep the updates coming
I've not done a turbo conversion before so it seemed an exciting project once I started looking into it. It invariably makes more sense to just buy a better/faster car than take on this kind of project, but for me this is more fun. The car cost £430, I've a spreadsheet saying that I've spent roughly £1k on turbo conversion parts, £600 on further modifications and aftermarket parts, plus £500 on service items and standard replacement parts, that's an honest account of the spend. So it all owes me about £2.5k... Seems like quite a lot to spend, but I've really penny pinched and bought cheap and used parts, so the spend could have been a lot more, plus I have done and will do all the work myself so no labour costs. To show for it I will have a restored, relatively rare V6 sports coupe with a 250bhp engine, so on those grounds I can justify it to myself! I've thought about what I could have bought for similar money and there isn't that much that really interests me...
A bit of progress, I got the intercooler securely mounted. I started with a mock-up to get the position I wanted, I found a shelf bracket laying around so modified it to hang the intercooler. I've positioned it quite tightly behind the air intake opening in the front bumper between the fog lights, and offset it somewhat to the left to allow enough room for the couplers and charge pipe bends. There is an M5 threaded hole already in the support panel.
I fabricated some brackets from some 30x4mm flat steel bar I bought for the purpose, just cut them to length and hammered in the right angle bends, then drilled some mounting holes.
To mount the lower brackets I had a rummage around and found some long enough bolts (that previously mounted the AC compressor in fact) to pass through the lower frame box section.
So it's nice and solidly mounted, I've now started to refit parts and look at chopping the charge pipes to length. At some point I will put some satin black on the brackets but for now I want to try and get things build. The modified front engine mount is back on, knife and forked it so that it clears the new exhaust as there was an interference before.
I fabricated some brackets from some 30x4mm flat steel bar I bought for the purpose, just cut them to length and hammered in the right angle bends, then drilled some mounting holes.
To mount the lower brackets I had a rummage around and found some long enough bolts (that previously mounted the AC compressor in fact) to pass through the lower frame box section.
So it's nice and solidly mounted, I've now started to refit parts and look at chopping the charge pipes to length. At some point I will put some satin black on the brackets but for now I want to try and get things build. The modified front engine mount is back on, knife and forked it so that it clears the new exhaust as there was an interference before.
I'm now getting back on the turbo project following the Xmas hiatus, I was abroad for a few weeks over the holiday period so haven't made any progress for over a month. Feeling motivated again to get the thing on the road for late spring so will be pushing it over the next couple of months, managed to get out to the garage the Monday evening.
The new radiator was trial fitted, I've changed the position of the rad mounts to relocate them to the left somewhat. This allows an opening for the charge pipes to pass through at 90 deg to the intercooler and emerge into the space directly below the turbo. As I'm using a same-side intercooler it will give nice short pipe length.
The oil sump was installed, plus got the exhaust manifolds properly on with the new gaskets and lambda sensors.
I received a couple of newly ordered parts recently. Bought the high pressure fuel pump as the standard one won't flow enough fuel when the engine is on boost. I also got a new cat as the old one had seen better days. I had a problem getting the '6 to pass MOT emissions previously so I'm hoping the new lambda sensors and cat will help sort things in that regard. The turbo shouldn't affect things as it won't be boosting for the idle and fast idle test.
The new radiator was trial fitted, I've changed the position of the rad mounts to relocate them to the left somewhat. This allows an opening for the charge pipes to pass through at 90 deg to the intercooler and emerge into the space directly below the turbo. As I'm using a same-side intercooler it will give nice short pipe length.
The oil sump was installed, plus got the exhaust manifolds properly on with the new gaskets and lambda sensors.
I received a couple of newly ordered parts recently. Bought the high pressure fuel pump as the standard one won't flow enough fuel when the engine is on boost. I also got a new cat as the old one had seen better days. I had a problem getting the '6 to pass MOT emissions previously so I'm hoping the new lambda sensors and cat will help sort things in that regard. The turbo shouldn't affect things as it won't be boosting for the idle and fast idle test.
Thanks for the positive comments. Ha, yeah I got a bit carried away and gave myself a lot of work to do and parts to buy! I reckon I have everything now so it's just a case of putting the hours in and getting the thing together.
I agree that it will be an unusual car, certainly not everyones cup of tea, but it's partly why I thought it would be a fun project. There aren't many left on UK roads now and It's not much of an enthusiasts car so there's few modified examples. I suspect mine could be the only turbo MX6 in the UK, I've not heard of another one. Not really surprising as the turbo exhaust kit isn't sold on these shore, as I previously mentioned I had to get this one and some other parts from the US/Canada.
I guess it's a bit crazy to do a turbo conversion like this on these cars and there are probably faster cars that you could buy for less. On the other hand, those Japanese turbo coupes from the '90's like the Supra, Skyline, 200SX, 300ZX, 3000GT, RX7, etc. cost significantly more these days and prices seem to be on the up. I'm not saying my MX6 will be directly comparable to those, as it's a car based on a FWD saloon, but there are some obvious similarities.
I agree that it will be an unusual car, certainly not everyones cup of tea, but it's partly why I thought it would be a fun project. There aren't many left on UK roads now and It's not much of an enthusiasts car so there's few modified examples. I suspect mine could be the only turbo MX6 in the UK, I've not heard of another one. Not really surprising as the turbo exhaust kit isn't sold on these shore, as I previously mentioned I had to get this one and some other parts from the US/Canada.
I guess it's a bit crazy to do a turbo conversion like this on these cars and there are probably faster cars that you could buy for less. On the other hand, those Japanese turbo coupes from the '90's like the Supra, Skyline, 200SX, 300ZX, 3000GT, RX7, etc. cost significantly more these days and prices seem to be on the up. I'm not saying my MX6 will be directly comparable to those, as it's a car based on a FWD saloon, but there are some obvious similarities.
Wow this is getting serious.
I'm really interested in the MAF conversion - can you link up some details?
I used to run a 205gti which had a big of barn door style AFM, and I always thought it would be possible to fit a MAF and a little box of tricks that converted the signal to and appropriate format to get rid of it!
I'm really interested in the MAF conversion - can you link up some details?
I used to run a 205gti which had a big of barn door style AFM, and I always thought it would be possible to fit a MAF and a little box of tricks that converted the signal to and appropriate format to get rid of it!
The VAF to MAF converter board is made by Pilot Engineering, it's basically a guy in Russia who has designed this and sells them, $75 US. The lastest version that I have uses a bluetooth interface which always you to set the mapping via an android app. You can connect a lambda sensor (either narrow or wideband) and monitor the signal via the app so it can be tuned to stoich.
http://max.pilotpowersupply.com/2016/02/01/pilot_v...
So far I've only hooked up some power and connected to the board via bluetooth, seems to work okay, but I haven't tried putting signals into it yet. It has some different settings to be used in various configuations. I have a set of bigger injectors, so I'm planning to try to map these so that the motor doesn't run rich at idle/cruise.
http://max.pilotpowersupply.com/2016/02/01/pilot_v...
So far I've only hooked up some power and connected to the board via bluetooth, seems to work okay, but I haven't tried putting signals into it yet. It has some different settings to be used in various configuations. I have a set of bigger injectors, so I'm planning to try to map these so that the motor doesn't run rich at idle/cruise.
Edited by MX6 on Wednesday 23 January 15:15
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