Discussion on the potential of the 7MGE

[dexterrogers]

I was looking to build a powerful naturally aspirated Toyota motor for my 85 Supra. I though of the 2JZ, the 1UZ, even the Camry 1MZ, but for many reasons choose the 7MGE engine.

As it sits now air is fed through a ram air hood into three weber 45 DCOE's. The motor internals are stock. Exhaust is a Pacesetter header 3-2 to x pipe muffler combo to dual side pipe. Ignition is MSD 6A, Blaster II Coil, MSD Timing Control Computer. Power steering, clutch fan and a/c have been removed. Fuel is supplied by a Carter 4070 race fuel pump. As it sits now it will start and run, but I haven't started tuning the carbs yet.

Any thoughts on the expected output? Future modification includes cams & gears, springs, rods, 12:1 pistons 85mm bore (or 84.4mm if need be), high flow oil pump and accusump, and a good porting job. Looking to raise the redline some. Any predictions on power levels once complete?

Open for discussion! Like it? Don't like it? Think it will be powerful or it will suck? I figure people are making good power from those single cam Datsun engines, why not a a 7M?

Pictures
http://picasaweb.google.ca/DexRog/NewAlbum1909081108PM?feat=directlink

 

[gaboonviper85]

250 ish at the most LOL! You picked the wrong motor for naturally asp power....and this is the wrong section to post 7mge questions..

 

[AJ'S 88NA]

Not the wrong section to post.

I'd say 250-275, sure should rev pretty quick.

 

[pogoism9]

I love those TBs!

Personally though, I would have gone with a 90-96 1UZ if you want a better platform to start with. As stated before, its really hard to get big power from a 7MGE and to a lesser extent a 2JZGE. They just dont have any balls on the bottom end, where the 1UZFE makes 200 lb/ft @1000 and peaks at 260 or 270 (varying by year), so you are pretty much good for the whole powerband. Its real hard to find an SC400 that has the original quarter panels on it, where the SC300 doesn't have that problem. Its just a case of low end balls between the 2 cars.

Needless to say, I hope you meet your goal, because it would be truly badass to see a potent 7MGE without a giant turbo strapped to it.

 

[dexterrogers]

thanks for the input! my question is why is there a general concensus that the 7M is a poor platform to start with? I've read all of the N/A power/build/problem threads, but I still don't understand why this motor would be any different than any other. With a strong bottom end, good oiling, good gaskets and a built head I would think it should handle a higher redline. Piston velocity is high, but what are the dangers of high piston speed? Throwing a forged eagle rod? Ruining the clevite bearings? Not enough oiling from the high flow pump and pre start lubrication/low oil pressure release system? I've herd of triple webered 7M's used in race boats back in the day, I wonder what the specs were on those motors, and the lifespans..

 

[AJ'S 88NA]

If you are not going to stroke it the piston speed shouldn't be a problem. If you are or if not then lighter weight components, i.e. pistons, rods, and a lightened, flycut, and balanced crank helps with the piston speed not to mention the lighter components will make it rev faster. I've seen 7300 rpm with my stroked 7MGE.

 

[empera]

its a waste of money, maybe if u swapped the GE into something lighter.

 

[benchwarmer]

The big reason why so many people doubt the GE is that so few people have actually tried to make power with it and most of those who have didn't achieve much. Bolt on mods on the 7M give a negligible power gain. The motor was really designed with a turbo in mind so to gain any real power internals need to be changed and the head worked over. Since that requires a rebuild and substantial money, it's easier and cheaper to just go turbo and be happy.

While I truly respect the members of this board and there is an unbelievable wealth of knowledge here, very few of the members have any experience building NAs. Take the advice you get on this topic with a grain of salt as most of it is going to be conjecture. For myself, I love the sound and the drive of an all motor car so I wish you the best.

Dangers of high piston speed as explained by SupraCentral: http://www.supramania.com/forums/showpost.php?p=180719&postcount=18

 

[benchwarmer]

If you are not going to stroke it the piston speed shouldn't be a problem. If you are or if not then lighter weight components, i.e. pistons, rods, and a lightened, flycut, and balanced crank helps with the piston speed not to mention the lighter components will make it rev faster. I've seen 7300 rpm with my stroked 7MGE.

Piston speed increases with RPM as well.

its a waste of money, maybe if u swapped the GE into something lighter.

MKIIs are lighter. I stripped down MKII with a high power 7M should be a blast to drive.

 

[cuel]

There's a Comp Cam BBC inner valve spring that fits perfectly on the 7m head, with much better characteristics. I don't have the part number handy, but it's here if you search. There's a ton of work you can do to the head to increase flow, such as porting the runners and deshrouding the valves. Talk to AJ about his cams, iirc, he's got a good regrind. I've also seen using 2JZ valves discussed, and sounds like it would work well with a reground cam, as there is a length difference in the stem that the cut on the cam would make room for? Shimless buckets would also be worth you looking into as well.

Good luck man, and happy building. Hope some of this helps.

 

[dexterrogers]

I like the BBC springs, I wonder has anyone really reved them a lot though? Do you think they would perform well at 7500RPM with brief stints up to 8000? Paeco.com makes some extreme cams>

TS7-8000: This is an all-out racing grind for well-prepared engines only. The cams provide fantastic power in the 3500-8000 RPM range and will rev to 8500 RPM. INTAKE: 50/86 EXHAUST: 86/50 DURATION: 316 LIFT: .417"

But for some reason welded and reground cams leaves a bad taste. Really though I don't know if they would wear the same or faster, or slower... Also that seems like a lot of lift? I was thinking bucket over shims, but shimless would be better yet? Is coil bind a concern? Crower makes some nice sounding cams too.


(7300 rpm with my stroked 7MGE)
I've considered stroking the motor to 3.3 with a Paeco crank, but I feel the redline should be lowered with the longer stroke, and since much na power comes with revs and my intake certainly supports them I now plan to bore the cylinders to either 84.5 or 85mm. At 85mm the 7M is damn near 3.1L, not bad. Thats cool you have a stroker motor, i'll look it up.

 

[BLACKCAT]

My 7MGE has around 250hp at the flywheel:
Auto
BC 264 cams
extractors
modified exhaust
ported head
BBC springs

 

[AJ'S 88NA]

Hard weld regrind cams are fine.

A lift of .400+ would be very close to an interference motor. You might have to make room for the extra lift. Also if you go with bigger valves that would be a concern.

I would think the BBC springs could rev 7500-8000. It's keeping everything else in place at those RPM's.

To make use of the cams, yes a good port job.

To make use of everything else a standalone or piggy-back would be necessary, you have to be able to tune.

With .60 over size pistons and a stroked crank you would be looking at around a 3.28 in displacement.

A lot of money and work as I've said before, and as others have said much easier to go turbo. But there are a few that are willing to do it and like the NA.

Search for Defiants 101 mm stroker. Doesn't look like he ever got it up and running

 

[Poodles]

Because horsepower is a calculation based on torque and RPM, the higher you can rev, the more horsepower you will make (if it will flow enough).

The reason people don't mod the piss out of a GE is that a GTE is by far a better choice in the HP/$ ratio. Not to mention the torque...

Now, with 4.30 gears, badass cam, lots of port work, and a redline on the ragged edge of sanity it might be a pretty quick car. Just don't be mad when the ebay modded GTE blows past you...

 

[AJ'S 88NA]

The big reason why so many people doubt the GE is that so few people have actually tried to make power with it and most of those who have didn't achieve much. Bolt on mods on the 7M give a negligible power gain. The motor was really designed with a turbo in mind so to gain any real power internals need to be changed and the head worked over. Since that requires a rebuild and substantial money, it's easier and cheaper to just go turbo and be happy.

While I truly respect the members of this board and there is an unbelievable wealth of knowledge here, very few of the members have any experience building NAs. Take the advice you get on this topic with a grain of salt as most of it is going to be conjecture. For myself, I love the sound and the drive of an all motor car so I wish you the best.

Dangers of high piston speed as explained by SupraCentral: http://www.supramania.com/forums/showpost.php?p=180719&postcount=18

There are a few of us that have been running a stroker for a while now with out any problems. And several other threads on stroked 7M's
http://www.supramania.com/forums/showthread.php?t=75181&highlight=stroked+7m

 

[cuel]

I'm pretty sure I remember seeing a destroke kit as well, which might help increase your rev limit while maintaining a safe piston speed? Iirc, the 2JZ uses a bigger bore with a shorter stroke, and has a higher rev limit.

 

[IJ.]

I like the BBC springs, I wonder has anyone really reved them a lot though? Do you think they would perform well at 7500RPM with brief stints up to 8000? Paeco.com makes some extreme cams>

TS7-8000: This is an all-out racing grind for well-prepared engines only. The cams provide fantastic power in the 3500-8000 RPM range and will rev to 8500 RPM. INTAKE: 50/86 EXHAUST: 86/50 DURATION: 316 LIFT: .417"

But for some reason welded and reground cams leaves a bad taste. Really though I don't know if they would wear the same or faster, or slower... Also that seems like a lot of lift? I was thinking bucket over shims, but shimless would be better yet? Is coil bind a concern? Crower makes some nice sounding cams too.


(7300 rpm with my stroked 7MGE)
I've considered stroking the motor to 3.3 with a Paeco crank, but I feel the redline should be lowered with the longer stroke, and since much na power comes with revs and my intake certainly supports them I now plan to bore the cylinders to either 84.5 or 85mm. At 85mm the 7M is damn near 3.1L, not bad. Thats cool you have a stroker motor, i'll look it up.

Been using my pair for 3>4 years now no issues at all if they're done properly.
(Mine were done with Hard Face rods NOT plain cast iron)

I used to run my motor to 8300+ daily but suffered a spring failure using Ferrea Dual's, if it wasn't for the dual's I'd have lost the engine, since then after Cryo treating the springs and lowering the RPM limit it's been fine.

 

[benchwarmer]

There are a few of us that have been running a stroker for a while now with out any problems. And several other threads on stroked 7M's
http://www.supramania.com/forums/showthread.php?t=75181&highlight=stroked+7m

I know you run a stroker. Honestly if I could afford it, I would too. I was just answering his question about piston speed.

 

[AJ'S 88NA]

I know you run a stroker. Honestly if I could afford it, I would too. I was just answering his question about piston speed.

Yeah I know just pointing out there is a few other threads about strokers. I was looking for the one that tells you a little more about piston speed and how to figure it.

 

[Doward]

You are forgetting one huge factor here.

Static compression ratio. Increase it. Go with a set of max quench flattops, and aim for 11:1 compression. Giant cams. Lots of spinning, with some 4.30s out back with a short throw W58 would be a SERIOUSLY fun car.