SAVAGE ³
24-12-2011, 06:57 AM
I’ve had a few people ask about my mivec conversion, so I’ve done a short brief write-up for what’s involved. For this I am starting this write up halfway through, so I’m assuming you know how to take the heads off the motor. I am also assuming a high level of mechanical aptitude, because I haven't gone into every little tiny detail.
http://img9.imageshack.us/img9/1154/1001302hp.jpg
There are two known variations of the 3.8L mivec heads. The oil crossover and the non-oil crossover type, the difference is that the crossover type only has the one oil control valve controlling the mivec function on both heads with an oil crossover line connected between the two heads. The non-crossover type has two oil control valves both controlling the mivec function on their own heads – no oil crossover line.
From what I am aware of, we only have the crossover type here in Australia, on the pajeros. I could be wrong. Eariler model eclipses/galants used the non-crossover heads while the later models used the crossover type – probably to save costs.
Before I bolted the heads on I checked for interference of the valves on the pistons. The mivec pistons have valve reliefs where as the non mivec 380 pistons do not. I recommend checking clearance with the magna pistons before putting the mivec heads on to a 6G74 block. I done this by putting a thin layer of plasticine on top of the pistons, bolting down the mivec heads, doing the timing belt up, manually engaging the mivec on each cylinder and cranking the motor over by hand for a dozen revolutions. Pull the heads back off and check for any indentaions in the plasticine, indentations equal valve fouling. I can safely say these heads bolt onto a 380 block without valve interference issues, I am unsure about the magna block. These heads could also be more susceptible to damage if you even get the timing out by one tooth.
http://img196.imageshack.us/img196/3084/photo2cxg.jpg
Clean the mating surfaces of the heads and block, and drop the head gaskets down on the locators on the block making sure they are the right way up and the ports are properly aligned. Drop the heads on top carefully and bolt down as per the tightening diagram in the eclipse/galant/pajero workshop manual. Torque to the required value.
Before bolting up the water rails you’ll need to decide how you are going to attach the distributor to the engine. There are two ways to attach the distributor to the engine, either on the front or the rear head, each way has its own pros and cons (cost vs. appearance). If a 380 you should be able to use the pajero cam angle sensor and mount it on the front bank, but you’ll need to check the configuration first.
Mounting the distributor to the front head requires the water rail to be modified, and a spacer/mounting bracket to be made up. When this is made you’ll need to pay attention to the angle you attach the distributor to the bracket because if you are out, you can retard or advance the timing of the ignition. This is probably the cheaper way of doing things. You’re on your own here.
http://img714.imageshack.us/img714/4104/photo10ej.jpg
http://img59.imageshack.us/img59/2745/photo5mc.jpg
http://img807.imageshack.us/img807/4093/photo8t.jpg
http://img217.imageshack.us/img217/4903/photo0242cv.jpg
http://img806.imageshack.us/img806/3779/photo0243f.jpg
http://img689.imageshack.us/img689/6646/photo0245h.jpg
http://img580.imageshack.us/img580/4646/photo0241.jpg
http://img81.imageshack.us/img81/5556/6g75swap21.jpg
The second way of mounting the distributor is a lot more expensive as precision machining will need to be done and a n extension to the cam shaft made, but will look more factory. I will update this post when I can get some photos together.
http://img703.imageshack.us/img703/4905/photo3fh.jpg
http://img821.imageshack.us/img821/8295/photo1av.jpg
After the distributor is mounted, the water rail can be put back on and plumbed back in. If the distributor is mounted on the front head, you’ll need to modify the water rail. If mounting to the rear head the water rail will bolt on, however some of the smaller water pipes that feed the heater core will need to be bent around the oil control valve and new mounting tabs braised on.
The existing magna/380 exhaust is a straight bolt on, along with any brackets. Timing belt is the same, new timing belt covers are required – part numbers are provided at the bottom of this post. Alternator and power steering pump can be put back on, CAS plugged back in.
The mivec heads have larger inlet ports than the magna/380, you can either use the magna/380 lower intake or the gallant one. I have an unused lower manifold and gaskets from a ralliart gallant here that I’ll sell for $200 ($600+ new) if you wanted to go that way (then you’ll need the upper manifold as the magna/380 will not bolt up – part number 1542A021 from the US). The runners and ports are wider on the ralliart galant manifold than the magna/380 equivalent.
The rocker covers on the mivec heads are twice the height of the non-mivec variety. For my build I had to cut the height of the rear rocker cover in half because of the sprintex supercharger that would sit on top of it would foul. If you are using a standard magna/380 intake plenum, the rear rocker cover may need modifying to be able to fit the plenum on top of it, keep this in mind.
http://img841.imageshack.us/img841/5163/megaor.jpg
The crossover oil line for the pajero is cast, and therefore cannot be bent without splitting the line. The pajero crossover line was made to run around the pajero lower intake, but because you now have the magna/380 lower intake this will cause problems. I made a new hose out of stainless steel tubing and a couple of banjo bolt fittings. I had enzed come over my house to make and fit the hose.
Control of the mivec system can be done many ways. Most piggy back controllers should be able to manage it or you could use a vtec controller or rpm switch. I haven’t found the exact operating rpm switch point, but I am led to believe it is somewhere between 3000 and 4000rpm. Best results you’ll need to tune your car.
http://img9.imageshack.us/img9/1154/1001302hp.jpg
There are two known variations of the 3.8L mivec heads. The oil crossover and the non-oil crossover type, the difference is that the crossover type only has the one oil control valve controlling the mivec function on both heads with an oil crossover line connected between the two heads. The non-crossover type has two oil control valves both controlling the mivec function on their own heads – no oil crossover line.
From what I am aware of, we only have the crossover type here in Australia, on the pajeros. I could be wrong. Eariler model eclipses/galants used the non-crossover heads while the later models used the crossover type – probably to save costs.
Before I bolted the heads on I checked for interference of the valves on the pistons. The mivec pistons have valve reliefs where as the non mivec 380 pistons do not. I recommend checking clearance with the magna pistons before putting the mivec heads on to a 6G74 block. I done this by putting a thin layer of plasticine on top of the pistons, bolting down the mivec heads, doing the timing belt up, manually engaging the mivec on each cylinder and cranking the motor over by hand for a dozen revolutions. Pull the heads back off and check for any indentaions in the plasticine, indentations equal valve fouling. I can safely say these heads bolt onto a 380 block without valve interference issues, I am unsure about the magna block. These heads could also be more susceptible to damage if you even get the timing out by one tooth.
http://img196.imageshack.us/img196/3084/photo2cxg.jpg
Clean the mating surfaces of the heads and block, and drop the head gaskets down on the locators on the block making sure they are the right way up and the ports are properly aligned. Drop the heads on top carefully and bolt down as per the tightening diagram in the eclipse/galant/pajero workshop manual. Torque to the required value.
Before bolting up the water rails you’ll need to decide how you are going to attach the distributor to the engine. There are two ways to attach the distributor to the engine, either on the front or the rear head, each way has its own pros and cons (cost vs. appearance). If a 380 you should be able to use the pajero cam angle sensor and mount it on the front bank, but you’ll need to check the configuration first.
Mounting the distributor to the front head requires the water rail to be modified, and a spacer/mounting bracket to be made up. When this is made you’ll need to pay attention to the angle you attach the distributor to the bracket because if you are out, you can retard or advance the timing of the ignition. This is probably the cheaper way of doing things. You’re on your own here.
http://img714.imageshack.us/img714/4104/photo10ej.jpg
http://img59.imageshack.us/img59/2745/photo5mc.jpg
http://img807.imageshack.us/img807/4093/photo8t.jpg
http://img217.imageshack.us/img217/4903/photo0242cv.jpg
http://img806.imageshack.us/img806/3779/photo0243f.jpg
http://img689.imageshack.us/img689/6646/photo0245h.jpg
http://img580.imageshack.us/img580/4646/photo0241.jpg
http://img81.imageshack.us/img81/5556/6g75swap21.jpg
The second way of mounting the distributor is a lot more expensive as precision machining will need to be done and a n extension to the cam shaft made, but will look more factory. I will update this post when I can get some photos together.
http://img703.imageshack.us/img703/4905/photo3fh.jpg
http://img821.imageshack.us/img821/8295/photo1av.jpg
After the distributor is mounted, the water rail can be put back on and plumbed back in. If the distributor is mounted on the front head, you’ll need to modify the water rail. If mounting to the rear head the water rail will bolt on, however some of the smaller water pipes that feed the heater core will need to be bent around the oil control valve and new mounting tabs braised on.
The existing magna/380 exhaust is a straight bolt on, along with any brackets. Timing belt is the same, new timing belt covers are required – part numbers are provided at the bottom of this post. Alternator and power steering pump can be put back on, CAS plugged back in.
The mivec heads have larger inlet ports than the magna/380, you can either use the magna/380 lower intake or the gallant one. I have an unused lower manifold and gaskets from a ralliart gallant here that I’ll sell for $200 ($600+ new) if you wanted to go that way (then you’ll need the upper manifold as the magna/380 will not bolt up – part number 1542A021 from the US). The runners and ports are wider on the ralliart galant manifold than the magna/380 equivalent.
The rocker covers on the mivec heads are twice the height of the non-mivec variety. For my build I had to cut the height of the rear rocker cover in half because of the sprintex supercharger that would sit on top of it would foul. If you are using a standard magna/380 intake plenum, the rear rocker cover may need modifying to be able to fit the plenum on top of it, keep this in mind.
http://img841.imageshack.us/img841/5163/megaor.jpg
The crossover oil line for the pajero is cast, and therefore cannot be bent without splitting the line. The pajero crossover line was made to run around the pajero lower intake, but because you now have the magna/380 lower intake this will cause problems. I made a new hose out of stainless steel tubing and a couple of banjo bolt fittings. I had enzed come over my house to make and fit the hose.
Control of the mivec system can be done many ways. Most piggy back controllers should be able to manage it or you could use a vtec controller or rpm switch. I haven’t found the exact operating rpm switch point, but I am led to believe it is somewhere between 3000 and 4000rpm. Best results you’ll need to tune your car.