square means the bore and the stroke are the same. maybe someone else can go into more detail? there is also oversquare and undersquare, i dont know what the 7m is though.
Bigaaron's "5M crank in a 7M" build thread!
- Thread starter bigaaron
- Start date
The 7m crank is 91mm stroke. The 5m crank is 85mm stroke. After seeing the inside of a lot of 7m engines, and noting the cylinder wall wear specifically on the sides , plus considering some of the higher hp 7m failures are rods bending, it made me think that the extra long stroke is a problem more then a asset. Now one thing long stroke does is it makes torque. The thing is that 85mm is not really considered "short stroke" compared to most engines. The 2jz is 86mm bore and 86mm stroke, square bore. Oversquare is when the piston diameter is larger then the piston stroke. That usually means less wear, higher rpm limit, and less friction, but at the cost of decreased torque. Undersquare is the opposite, bore smaller then stroke, like the stock 7m. Square bore seems to give a good balance of horsepower and torque. The 7m was built at the end of the M series run, and looking at what they did with the jz engines, I feel like I'm following Toyota's lead with what would have probably been changed on the 7m to improve it. I'll gain what I want in performance while not loosing substantial displacement. I've talked to some very knowledgeable engine builders, and they agreed with my thinking on this.
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bigaaron for president! Any idea what the rev limit will be? Hopefully something close to the 1jz's :love: ..... i m sure that would be a lovely powerband!
my project will be complete when the car is going sideways and it's bouncing off of the 8000rpm rev limiter!
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drumminforev
Guest
So how comes you still have so much interest in the 7m projects .... When you guys feel that the 1jz is best design for a piston engine?? No offense. OR is that this will the 7m very close to that ideal setup and be more reliable?
bountykilla0118 said:
Good question.
The 7m is like a challenge for me, a hobby. It's not my daily driver anymore.
I have a lot of money into all the accessories that go with the 7m already. We build a lot of 7m engines and I want to show what we can do with them. I still have some connection with the 7m, it's the first turbocharged engine I ever built, and something about it is just fun for me. It's a pain, but it's rewarding to see it run well.
I wasn't lying about the 1jz, and I don't think the 7m or 2jz is a piece of crap either. See, everything does not have to be black and white. You can like the 1jz and still like the 7m and 2jz for all their merits. Now when I think of the majority or people on this site who own a MK3, most of them it its their only car, and they are not independantly wealthy. Sure, if you build a 7m like mine and replace every single thing you see in the engine bay, plus have all the electronics to support it, it can be reliable and make some good power. I'll tell you right now, that will cost A LOT more then a 1jz swap, and take A LOT more time to get to that point. It would be about the same cost as a 2jz swap.
My wife's car is a 1jz, and it's her daily driver and my fun car on the weekends or at night. All I do is change the oil. We just took it to Vegas, bouncing it off the 120mph speed cut a bunch of times, and going 100mph up the biggest hills there and back, temp never budged, didn't burn any oil, and I was not worried one bit.
supramike7m said:
I'll let you know when it's done :biglaugh:
The most expensive part will be the rods. Once I get those made I could sell the rods and modified 5m crank as a destroke kit for 7m, and it will work with whatever size 7m piston you want to go with.
well said and thought out .... things arent black and white or just as simple as a yes or no. How much longer do you think it will be until you have it complete .... also thanks for not answering my PM!!!! lol j/k but i still want to know about that 1jz swap soooo PM me back bigA also where is Jose??? I wonder if he missing me bugging the hell out of him on AIM about the different engines every time he logged on!
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drumminforev
Guest
I really look forward to this. If I ever had a 7m again(probably not) I would LOVE a destroked one.
bountykilla0118 said:
We want the business, but sometimes I do take some time off and browse the forum for fun. If you REALLY want a fast reply, paypal me a deposit on the job :biglaugh:
bigaaron said:
lol classic that must be the business side of you well i have a roll of quaters ready to go :evil2:
