who here stands by the 7m and have 350+ hp reliably

[wiseco7mgt]

At the end of the day the 7m is getting pretty old now so most of the second motors are pretty screwed and nearly all would need building to get the most out of one if you are looking for good reliable results. The 1jz's or 2jz's are the slightly newer model with a few improvements so its easier to find a motor that has done low klms and without opening it up may provide you with a few good years of trouble free motoring, cause lets face it, the younger generation for the most part is lazy as shit and hates having to actually spend a weekend working on a car and would rather just go eat mac donalds and jack off with mates.(don't know where that came from!)
Now if you take a 7m and follow all the good advice that you find on here and find a good machinist, and use quality parts and run the motor in properly with a good tune by a reputable dyno shop, for me i'll take the 7m over the 1jz with exactly the same mods.Torque off the line at low revs gives me a horn and is something the 1jz cannot provide in a heavy ma70 body.
But with the same mods done i'll take the 2jz, anyday.

 

[Evilempire1.3JZ-GTE]

For 1 the oem head gasket paper vs metal enough said lets not even get into how toyota made that worse.

2 Yamaha & German engineering. (head design way superior)

For gods sake stop trying to B.S. this arguement JZ vs M
::dead horse::

 

[wiseco7mgt]

Who gives a shit about changing a head gasket? it's not hard to too. If it's such a big issue ride a bike, just don't bitch if your chain falls off.

 

[Doward]

At the end of the day, be happy with what you have.

Just don't go around point at everyone else's setup and calling it shit. If you ask me, most of the JZ fanboys are just trying to justify blowing $2k+, and still not having a solidly forged bottom end

Mike, I haven't sat down and calculated the piston speed yet, but I don't think the 5mm difference is going to account for much.

Screw it, let me do the calcs real quick

@ 7000rpm:

7M (91mm) = 4179.79 feet per minute
1JZ (71.5mm) = 3284.12 feet per minute
2JZ (86mm) = 3950.13 feet per minute

Both the 7M and 2JZ are right around 4000 feet per minute @ 7000rpm. Nothing a good forged rod with ARP bolts can't handle. Pistons (2JZ vs 7M) should be close to the same weight, with the 7M having the slight advantage. (83mm vs 86mm bore)

I'll admit, the 1JZ is a rev-happy SOB of an engine. The 7M gives up very little in the way of 'rev-ability' vs the 2JZ (provided you get the head flow increased) and has more stroke (torque) to boot.

I had a 2JZ practically given to me - I ended up giving it away, and deciding to build the 7M instead. Looking at my forged H beam rods and forged Probe pistons, I do not regret that decision in the least

*edit* As far as the 7M not taking abuse, here's a small taste of the problems that Jeff has put his through:

1) Wrong bearings in place: STD bearings on a .010" turned crank - did not register oil pressure at idle, registered 20psi at WOT - did that for about a week before he finally believed me and checked the bearings (machine shop screwed up)
2) Tune was completely 100% screwed
3) Ran with the coil wires plugged into the wrong coil packs (fixed since then, lol)
4) Exhaust cam retarded by a tooth, and intake cam advanced by a tooth (also fixed)

The car turned around and ran within a car length of a known 122mph trapping local C5 vette, and walked a ~116mph WRX.

The 7M is just as die hard. Don't knock it just because it'll let you know when you screwed up.

 

[chefma70]

No, it doesn't.

Please provide me with a good, mechanical reason for the 7M to fail.

The late model 7M block has the same block strength as the JZs, and IIRC BIGGER head bolt and main bolt fasteners.

The JZ engine, as much as it'll hurt the JZ riceboys, only has THREE base line mechanical improvements over the late model 7M engine - better flowing head, metal gaskets stock, and hypereutectic pistons.

In other words, the JZ is more forgiving than the 7M when you screw up.

The 7M won't put up with half assed BS. I'm completely fine with that., because I won't either

you are the man.

i want to put up that winking puppy thats sais whos cool ur cool...lmao

thats gona b my philosophy when i build my 7m no half assed construction and no cheap parts

 

[GrimJack]

Screw it, let me do the calcs real quick

@ 7000rpm:

7M (91mm) = 4179.79 feet per minute
1JZ (71.5mm) = 3284.12 feet per minute
2JZ (86mm) = 3950.13 feet per minute

The calculations aren't that simple, I'm afraid. To get a true idea, you'd need a whole lot more factors.

First of all, who spins their 7M to 7000? The real question is, with similar setups, what RPM does each engine have to spin at to get, say, 400whp? The 7M will be lower, and that will affect your piston travel over time. It will probably drop it below the JZ series... probably.

However, the piston speed will probably still be higher on the 7M... probably. The simple method of stroke & rpm to calculate it is a very rough approximation, as the piston doesn't move at the same speed due to the fact that it's attached to a rotating crank - so it moves slower at the top and bottom of the stroke and faster in the center of the stroke.

Then you need to worry about rod / piston weights, ring locations and materials, oil composition, air intake filter efficiency, and half a hundred other factors.

Bottom line... who has seen a longblock actually wear out? I've done it to a 22R engine... at well over a million kilometers. I've never seen it happen to a 7M ORa JZ. It's always something else - coolant hose pops, engine overheats, engine seizes... or something similar. Faulty part? Coolant hose. Are the coolant hoses on the JZ engines better than the ones on the 7M engines? Errr... no.

 

[Doward]

The calculations aren't that simple, I'm afraid. To get a true idea, you'd need a whole lot more factors.

First of all, who spins their 7M to 7000? The real question is, with similar setups, what RPM does each engine have to spin at to get, say, 400whp? The 7M will be lower, and that will affect your piston travel over time. It will probably drop it below the JZ series... probably.

However, the piston speed will probably still be higher on the 7M... probably. The simple method of stroke & rpm to calculate it is a very rough approximation, as the piston doesn't move at the same speed due to the fact that it's attached to a rotating crank - so it moves slower at the top and bottom of the stroke and faster in the center of the stroke.

Then you need to worry about rod / piston weights, ring locations and materials, oil composition, air intake filter efficiency, and half a hundred other factors.

Bottom line... who has seen a longblock actually wear out? I've done it to a 22R engine... at well over a million kilometers. I've never seen it happen to a 7M ORa JZ. It's always something else - coolant hose pops, engine overheats, engine seizes... or something similar. Faulty part? Coolant hose. Are the coolant hoses on the JZ engines better than the ones on the 7M engines? Errr... no.

Jeff (7MBoost) runs 7000rpm on a custom reground 218 degree cam set, and I'll be revving even higher (7200-7500rpm) with a set of TRD cams, most likely.

The quick calcs I did are a good indication of maximum speed the piston will likely see. I was simply illustrating that the JZ doesn't have any magic sauce from the factory that was left out of the 7M

 

[wiseco7mgt]

Guys just on the wearing out of a 7m long block, i bought a cressida 7m that had done over 300,00klms and it had very minimal wear in the bores, you couldn't feel a lip at all.To top it off the oils used in it was pretty much the cheapest the people could afford to buy at the time. Bloody amazing.
You'd definitely get a 7m to do over 1 000 000 klms, a few rebuilds later of course.

 

[figgie]

7m here!

Why?

Try driving any other engine with ZERO oil pressure due to #4 bearing saying bye-bye for 30 miles without the motor ever seizing etc and see how they do!!

My car, has never ever left me stranded. EVER.

 

[Zapp]

7m here!

Why?

Try driving any other engine with ZERO oil pressure due to #4 bearing saying bye-bye for 30 miles without the motor ever seizing etc and see how they do!!

My car, has never ever left me stranded. EVER.

Lol, Mine had a massive oil leak that I didn't catch for almost a week, by the time I caught it I had around 1qt of oil left. I was able to drive almost a week with very little oil, and I still have no rod knock.

I think I will stand by the 7M. :icon_bigg

 

[1987mk3]

7m all the way guys and gals!!!!

 

[SideWinderGX]

No, it doesn't.

Please provide me with a good, mechanical reason for the 7M to fail.

The late model 7M block has the same block strength as the JZs, and IIRC BIGGER head bolt and main bolt fasteners.

The JZ engine, as much as it'll hurt the JZ riceboys, only has THREE base line mechanical improvements over the late model 7M engine - better flowing head, metal gaskets stock, and hypereutectic pistons.

In other words, the JZ is more forgiving than the 7M when you screw up.

The 7M won't put up with half assed BS. I'm completely fine with that., because I won't either

By JZ do you mean both the JZ engines or just the 2JZ?

 

[Mo87NA]

By JZ do you mean both the JZ engines or just the 2JZ?

I'm assuming he means both. I'm trying for 500 "reliable" rwhp

-Mo

 

[SideWinderGX]

I'm assuming he means both. I'm trying for 500 "reliable" rwhp

-Mo

Me too, but I want a confirmation...better safe than sorry :icon_bigg

And good luck!

 

[Sawbladz]

Mean Piston speed = 2LN

L = stroke
N = rotational speed of the crankshaft

Instantaneous piston speed is much higher than the mean piston speed.

Speed instantaneous / Speed mean = (Pi/2)*sin@ [ 1 + (( cos@)/ ((R^2 - sin^2@) ^ 0.5)) ]

@ = theta = angle of rotation of crankshaft
R = l/a
l = rod length
a = crank radius

I think I finally have a suggestion for this forum... an equation editor. lol

Heywood, John B. Internal Combustion Engine Fundamentals.New York: McGraw-Hill, Inc., 1988

I also found this online. Seems pretty interesting and explains it well.

http://www.wfu.edu/~rollins/piston/

 

[IJ.]

I don't think it's so much the piston speed as it is the change of direction, there are plenty of engines revving to 8000 on longer strokes.

Rod and rod bolt strength becomes critical if you going to play up there for sustained periods, I replaced all of my bottom end fasteners on a semi regular basis even though Pauter said it wasn't needed.

 

[tekdeus]

With its 5mm longer stroke, how much more torque on average does a modded (400hp) 7M make over the 2JZ?

 

[mattsplat72]

I stand by my 7m, every time it let me down I had let it down first. Like going sideways with low oil. (Rod Knock #1) Na rad gave way after turbo swap ( BHG ). Didn't do BHG fix right leaked oil while racing a MR2 (Rod Knock #2). I got a 300$ short block from KWNate did it right that time and went up the Back side of Stevens pass ELEV. 4300+ at speeds in excess of 100f last june car is running great at 13psi. So who was at fault the 7m or ME?

 

[SupraOfDoom]

I've never had any big problem with a 7m for 7 years now. Daily driven..... I love the JZ series as well but the torque of the 7M makes me keep this motor.

 

[Zapp]

With its 5mm longer stroke, how much more torque on average does a modded (400hp) 7M make over the 2JZ?

I too am curious about this.