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6MGE thread (JDM inside)

48K views 61 replies 30 participants last post by  williamb82 
#1 · (Edited)
To help alleviate a lot of misinformation, or at least most of it, I decided I should make a thread for and about the (in)famous 6MGE.

Starting with new newbiest of all newb information, JDM simply stands for Japanese Domestic Market e.g. did not come to the United States. This engine is a very good example of JDM, as it was only ever produced and sold in Japan and nowhere else.

The 6MGE seems to be the "unicorn" of our small little Supra engine family, although it was never factory installed in a Supra. Though the 2JZGTE is obviously the most famous, most powerful and most durable engine people have squished into their cars, the 6MGE is the rarest. It is the missing link, the gateway between two generations of M engine in the mk2 and mk3 Supra. The 3.0 liter displacement of the 7M with the lesser flowing 12 valve cylinder head. Many people prefer the lesser performing, but more attractive style 12 valve head with it's classic ribbed valve covers and unique V-shaped cam towers.

MS125 Toyota Crowns and MZ12 Toyota Soarers were the only cars to ever have this engine option.

While many sites list this engine to have an output of 190hp, this was recorded at a time where Japan was using a different hp rating method. However, it should be noted that the Toyota Crown came with a Karman Vortex style AFM, allowing for better airflow and tunability. It is guesstimated that a 6MGE on stock Supra electronics will have around 175 crank hp (no upgrades, YMMV)


Technical specs:


Manufactured between 1984-1987
175hp/175ftlbs?? -USDM electronics, exhaust and emissions
190hp/192ftlbs?? -JDM Crown Karman Vortex AFM, electronics, exhaust, etc

2954cc (180ci)
3.27" bore x 3.58" stroke (83mm x 91mm)
9.2:1 compression (180psi)

The 6MGE uses the "6M" stamped crankshaft, which has less balancers than the later model "7M" stamped crankshaft, making it a few pounds lighter and revs to 6500rpm.

A 6MGE block will have "6M" stamped onto the left side of it, near the oil filter.


Another obvious visual cue would be the "3000" intake plenum, which is nearly identical to the 1984-86 5MGE intake with it's better flowing (than '82/83 5MGE) D shaped runners, but with no EGR system attached. People in smog states regularly install their OEM intakes onto the 6MGE to pass emissions, so the stamp on the block is the #1 identifier of a 6MGE



The swap:
Most imported 6MGEs come with a mid sump oil pan, which needs to be swapped to your front sump 5M oil pan.

For 1982-1983 Supras, the alternator or it's pulley needs to be swapped to the newer ribbed belt style. The entire oil pump and pickup assembly needs to be swapped over also. Some small grinding my be required if the engine cannot be turned by hand afterward, generally due to a rod bolt contacting the oil pump tube union.

For 1984-1986 Supras, just the oil pump pickup tube and strainer assembly.

All Supras will need to use their original throttle body, and depending on your state's emission laws, the entire intake plenum as well, as the 6MGE's intake did not have an EGR system. Lastly, the a/c compressor bracket.


The DIY 6MGE Frankenmotor:

So we now all know that the 6MGE was only made for 3 years and only put into 2 different cars, it has been made abundantly clear recently that these engines are not readily available for importing anymore, so people have begun making their own.

Parts off a 5MGE you need:
oil pressure sending unit (next to oil filter)
5m oil pump/ pick up
5m oil pan
male to male fitting that you screw the oil filter on to (unless u wanna drop $40 on a relocating kit from summit racing)
5m motor mounts
dip stick and tube
rear timing belt cover and water pump
the suicide pipe that bolts to the back of the water pump housing that goes around the back of the block
any block off plates
fuel filter, mounting bracket
intake plenum for EGR if needed
cylinder head
pistons (from 82-83 are the same as stock 6M pistons, making it 9.2:1 compression, using the 84-86 pistons will bring it to around 9.6:1 compression)

Low comp piston pic:


High comp piston pic:


Also;

SupraFiend said:
Frakenmotor: Ugh, don't use the 7m timing sprocket or oil seal, use the 5m ones! This commonly posted misinformation screwed me when I built my motor. The 5m sprocket works just fine on the 6m crank, and puts the timing belt and crank pulley right where it needs to be with the 5m inner timing cover. The diameter of the insert of the 5m sprocket is different then that of the 6m or 7m sprocket, you will end up with a giant oil leak if you use the wrong seal. The 7m & 6m crank pullies both work just fine with the 5m sprocket. The 6m timing sprocket is unique to the 6m, it has the length of the 5m sprocket with the insert diameter of the 7m sprocket and requires the 7m oil seal.

Little known fact, 86 5ms (from 86 mk2s) and probably 86-88 Cressida 5ms all used the 6m lower outer timing cover, which is clearanced for the larger snout diameter of the 7m\6m crank pulley, and its stamped 6M too! The 5m outer cover can be modified to work too of course, don't use the 7m one though if you want it to line up with your upper cover.
pre-86 5MGE cover on left, '86-88 5MGE cover and 6MGE cover on right;




Parts from a 7MGE/GTE you need:
7MGE or GTE block
By far the EASIEST engine block to use would be one sourced from a Cressida (1988-1992) as it is already front sump, so no need for drilling or swapping pumps!) (thank you RoadRipper)
7M connecting rods
6M or 7M crank (remember, the 7M crank will have all the weights and supposedly be "smoother" but won't want to rev as high as the lighter 6M crank)
7M oil pump driveshaft (it is notched for clearance, the 5M one will hit the crank)
7M front main seal
7M crank pulley bolt and woodruff key (always good to have replaced, as both get worn down over the years, about $12 from Toyota)

*note* It is HIGHLY recommended to have your parts machined, especially having the connecting rods resized and internals balanced with pulley/flywheel. A healthy cylinder head will only need minor milling to insure straightness.

There will be drilling involved, as the 7Ms were MID SUMP and we're obviously now converting it to front sump. On the front left side of the block, you will see a small, flat area that needs to be drilled out for the dipstick, and the stock one needs to be blocked off, a bolt and sealant will usually work well.

One of the most important, and frustrating aspects about this build is.... what about the harmonic balancer? Well, the 6MGE was unique in that it had a pulley with the same rib style as the later (1984-86) Supras, but fit on the thicker 3.0 liter crank snout.

Options:
a. wait it out and search for a 6MGE pulley on this forum or rinkya/yahoo japan
b. use a 7MGE/GTE pulley and forgo a/c (can be modded, see below), and most likely power steering (however some people have modified their power steering to work with this pulley)
c. have a machine shop hog out the inside of the 5MGE crank pulley, leaving VERY little metal left.... not really recommended IMO but has worked for some.



williamb82 said:
you can use ac on a 6m with 7m crank pulley. buy a compressor clutch for a 88 crown vic with 5.0v8. bolts right onto the 5m compressor. youll need a belt 2 ribs narrower though and it will leave a single rib unused on the crank pulley and clutch(at opposite ends of the respective pullies of coarse). this has been confirmed to work. I forget who i gave the info to, but they actually installed the ford clutch on the 5m compressor and it lined up as i mentioned. iirc jim king used this same compressor clutch setup on his 7mgte swap before switching to his r134 "kit"
Most of this DIY guide was brought to you by Lexusboy:
http://www.freewebs.com/partfinder/howto5m7mhybrid.htm

I probably left somethings out, but I'm sure someone will correct me and I will edit it in.

6MGE/GTE Inspiration

Russ Matusevich's 9.77 sec 6MGTE
http://www.turbomagazine.com/features/0103_turp_1985_toyota_supra_drag_car/viewall.html
 
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#34 ·
I got a little confused on the timing sprocket explanations...

If one has 6M/7M crank & 6M crank pulley, use either the 6M timing sprocket OR use a 7M timing sprocket machined down to the length of a 5M AND use a 7M front main seal?

If one has 6M/7M crank & 7M crank pulley:
1. Use 5M timing sprocket and 7M front main seal
2. Do NOT use 7M timing sprocket?

Anyone happen to have the measurements for the length of a 5M timing sprocket should one decide to machine down their 7M timing sprocket?
 
#35 ·
The 5M timing sprocket will work with ANY crank pulley, and just use the 5M front crank seal. The simplicity is the beauty of it. :)
You use the 6M or 7M crank timing sprocket if that is all you have. It takes the larger crank seal. The 7M sprocket has to be shortened, while the 6M one does not.

I agree, the sprocket length measurement would be nice to have in a thread. This way if someone only has a 7M sprocket, they can have it machined without having a 5M sprocket to compare it to.
 
#36 ·
I see pretty much everybody saying use a 7m block. Could a 5m with a 7m crank and rods work? If so ill just use my 5m block. And I can use the 5m crank pulley, as long as I use the 5m sprocket and 5m seal, correct? Confusion kicked in...
 
#37 ·
It will be obvious when you get there. It's really best if you have both 5m and 7m engines complete. Or at least a complete 7m bottom end.
 
#39 ·
So machining the block is required. I was informed that only the front was needed to be machined to fit the snout of the 7m crank.
 
#40 ·
Maybe, I think it depends what year the block is. Late 84-up may not need to be clearanced for the rods, because that is when the 6M first went into production. I think July is the month of the switchover to the new block. 84 is a confusing year to own (I had one!).

83CelWa put a 6M crank/rods/shaft into his overbored 5M block, so I know it can be done. With the 6M crank pulley and 5M externals, it looks just like a 5MGE!

The front inner lower timing case needs the crankshaft hole enlarged a little for the crank snout to fit through (not the part where the seal presses in though). It doesn't need to be enlarged by much. The front of the block is left alone.

I know you said you have an 84, so it depends what month the engine was made. Also, if your car has a 5 speed (originally) then it has the higher compression pistons and D-shaped intake runners also known as the performance package. If it was automatic, then the engine will have the lower compression pistons and round-port intake runners (like 82-83 engines). The electronics all stayed the same for 84.
 
#41 ·
Is there a date stamp on the block, or do I just go by the plate on the door? And yes it is a 5 Speed with the high comp pistons and d shaped runners.
 
#42 ·
well, i only have 4 front lower timing covers. none of them have the 6m on them. though i think at least 2 are for 7m's, they all seem to have the same size hole for the crank pulley to go through. ill measure them tomarrow, right now im just too tired to go that far into it. thinking of throwing together a stockish 6mge for the 85 since i have all the parts. 20 over 7m block, good std crank, std bearings. 20 over domed pistons and rings, several spare heads, though ill p&p one before it would go on. stock 6m crank pulley, etc... im going to use the 7m ati damper for my weber 6m build, and prolly forged pistons in a custom compression with eagle rods.
 
#45 ·
I'm in the process of building a Franken-6 using a 7MGE block. I'll be running OE 5MGE electrics, injectors, and intake (1985) along with a Pacesetter header and CAI. I've heard that some people have issues with the engine leaning out after 4500rpm. Has that been solved? I've done a lot of reading about the process and have the block stripped and honed, with new pistons, rings, bearings, etc on the way. During all this reading I've come across a few notes about Knock Sensors being different between the 5m and 7M, and wonder if this might be a source of any ignition or fueling problems if I use the 7M sensor with 5M ECU.

Also, is there any difference in the heads between 82 and 85 (valve size, cam profiles and timing, head gasket design)?
 
#46 ·
Was that an early 5m pickup Manvir? I don't recall having that problem, I ran a late 5m pump.

Rev, no major differences in the heads, but lots with the intake of course. You should be fine with all 5m electronics, just make sure you don't use the factory pacesetter 02 sensor bung. The sensor needs to be directly in the exhaust stream. You will likely run rich like most every 5m with a header and boltons does.
 
#49 ·
That cover info made me curious. I just had to pull the lower rear cover off my 6M because of a water leak due to a crap gasket. I checked my 8/84 built 5M and it had the smaller hole outer cover as expected. But I was very surprised that its lower rear cover had the larger hole for the 6M crank nose. Checked the EPC and indeed all "85" 5M's do. That changeover happened 8/84. More good info to know. Yeah, in both cases, it would have only taken a few minutes to clearance either cover. But now we know which ones don't need it.
It was also a good opportunity to fix an oil leak due to a crap Tennessee gasket. All the seals were fine but having everything this far apart, I replaced both lower seals. I thought it was strange that the 6M had a 5M crank pulley. Fortunately, I had both seals on hand.
It also has a cork oil pan gasket. WTF???
So, in case anyone is wondering if the lower rear cover can be removed and replaced without removing the head or oil pan with the engine in the car, WITHOUT any leaks, the answer is a definite yes! I was lucky in a sense as removing the cover didn't result in any damage to either gasket. I very slightly beveled the top and bottom rear edges of the cover to make it easier to reinstall without damaging either gasket. Yes, it's a very tight fit. But I aligned it perfectly and gently persuaded it back into position without damaging anything. Ok, the gently part is a bit of a lie. I had to carefully pry it off with 2 pry bars. Once I had it far enough on to be past the lead edges of both gaskets, I used a small dead blow hammer with a wooden block to "assist" it all the way back on.
I coated both the rear cover gaskets, Tennessee gasket and the front of the undamaged farging cork oil pan gasket with a very thin coat of Ultra gray after thoroughly cleaning every surface with acetone. And I reapplied FIPG at the top rear of the cover where it meets the block and head. I let the whole thing cure for a day and then added the oil and coolant. It's been 2 weeks and no leaks. Yeah!!!
As there's always been minor leaks around the oil pan and it has a pretty significant dent where the drain plug is, if I decide to drop the pan to take care of these issues, it'll be pretty easy to attach the cradle to hold the engine in place and drop the subframe like I did when swapping in a completely upgraded and modded front suspension, steering rack, brakes, Celica struts and steering arms and the 5 lug stuff. At least I now know why it's the way it is. Maybe I'll be lucky when I decide to drop the pan and the farging cork gasket will totally stick to the pan and not the block. Any bets?
 
#50 ·
I'll bet you a 5 pack that the gasket WILL BE stuck to the pan and not the block,Ray.(You keep one)
"Drop the pan" is a major ordeal. I did that twice in 2 months.:32:

While the pan is out,see what the oil pump screen looks like. Got sludge?
Weld up the oil pan after beating it into submission?Save the 1/4 turn drain plug,if possible.(I like mine,totally)

Like Tanya once said,"the 6M is a unicorn", all by it self. Just left over parts from the '84-'85 5MGE'S.
Then, we all say WTF?
Ray,I never see you ever post photos. Is that because you have a MAC?
 
#51 ·
I have the same water leak behind the lower rear timing cover. It's been leaking for almost 2 years now, finally it's gotten to the point I have to put 1/2 gallon in every day (fill resevoir and top rad off). I am not taking any chances with head gasket sealing there so I am pulling the entire engine for a re-seal since it's been 9 years (on 4/20!) and she's got a multitude of oil seeps

I wish my engine had made it 10 years before doing this but oh well. Most other people's builds from around that time have already blown up so I can't complain too much XD
 
#52 ·
I didn't see anyone posting up what belt to use with a True 6M, 6M timing Gear and 7M Supra crank pulley. I used a 4PK0925 which is a 4 rib belt. I wanted a 900(90mm long) or maybe 910, but the local shop had a 92.5mm belt in stock. This was with a 6M alternator(5M should be the same I think). It was a little on the long side, right about at the end of the tensioner, but it might actually be a good fit for both a 5M and 7M alternator in the 5M location maybe?(I didn't try to fit a 7M alt) I used a 4 rib belt not a 5, as I am driving it off the AC belt spot on the 7M Crank Pulley seems to line up well.
 
#54 ·
For those curious and since I cannot find anything on it.

6MGE with 83 electronics: AFR runs 14.5 to 15 cruising. Off throttle engine braking is also 14.5 to 15. Doesn't seem to lean out as in the injectors stay closed.
 
#55 ·
That's interesting. Just keeps burning fuel during decel? First efi car I ever heard that does that.
 
#62 ·
The 7mgte Metal head gasket is preferred, but if your going to use a stock gasket, use a %M as it is the same head.
 
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