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Turbo LAX
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274 Posts
Discussion Starter #1
Obvious which is what (2jz rod is fitted with ARP fasteners).

The 2jz rod is also 1mm + thicker on the beam thickness, it's also a better finished product compared to the 7m rod (both are excellent forgings) comparing them next to each other, rather than a "I was told this or I heard this from my mates mothers cousins sisters best friends brother " kind of bullshit.

The photo's speak for themselves, excuse my shit photography skills.

Enjoy.





 

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Turbo LAX
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274 Posts
Discussion Starter #3
Cheers, although you might as well link directly to the pictures - PM me if you like.

I shall add some pictures of the 1jz rod compared to the 2jz rod compared to the 7m rod - should give people a better understanding - Wastegate is supplying the 1jz rod, thanks buddy :)

I will have a 7m crank in my hands again soon to compare the 2j crank against it - It will probably be a 6m crank rather than the 7m crank (which was fully counter balanced rather than the semi counter balanced crank (6M)).

Cheers

Jon
 

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2JZ rods are known for bending at over 30+ psi of boost. So while strong, they are not one of the strongest links to the engine. At least thats what I have heard from a few people.
 

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the clever guy
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782 Posts
It's refreshing to actually *see* the comparison. However, this is only a visual comparison and doesn't reflect the properties and integrity of the materials used in the rods.

2JZ rods are known for bending at over 30+ psi of boost.
I've never heard that, but then again I don't do much reading on the 2j. The rods see two major stresses: compressive and tensile. I think that tensile loads have caused more failures than compressive.
 

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Impeller Head
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I measured the rods' big and small ends on both, did not expect them to be the same but they are dead on the same.
 

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I've been here forever.
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jt2ma71 said:
I measured the rods' big and small ends on both, did not expect them to be the same but they are dean on the same. Does this mean we can stroke the 2j by using 7m rods, crazy? the piston pin height would be so up there, right?
Would that work the other way also, use the 2j rods to destroke the 7m?
 

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Impeller Head
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Wouldn't the shorter rods make it higher revving motor just like what is done with the FORD 289s and swapping rods and or cranks on the Nissan L series motors? But I think low end torque will be decreased.
 
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If you used a smaller rod on a stock crank it will increase displacement and lower compresion...

Boostedsr8six- tensile is when the material is essentially stretches from both ends...Im pretty sure rod failure is usually due to the compression of the rods on the power stroke.
 

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Impeller Head
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Silver88Turbo said:
If you used a smaller rod on a stock crank it will increase displacement and lower compresion...

Boostedsr8six- tensile is when the material is essentially stretches from both ends...Im pretty sure rod failure is usually due to the compression of the rods on the power stroke.
Yeah, but if you change the piston pin height, will it not restore the compression? You will even have thicker ring lands. Right?
 

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stroke is controlled by the rod journal offset from the centerline on the crank, not by the length of the rod.
 
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jt2ma71 said:
Yeah, but if you change the piston pin height, will it not restore the compression? You will even have thicker ring lands. Right?
I assume you mean using a different, taller piston to accomplish this right? If so, it will not change anything. To make a shrter stroke and maintain compression you need to make the crank offset shorter and use longer rods. Make sense?
 

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Boostedstr8six said:
I've never heard that, but then again I don't do much reading on the 2j. The rods see two major stresses: compressive and tensile. I think that tensile loads have caused more failures than compressive.
I saw a 35PSI overboost on someone's car at the track. End result was a bent rod :( Possible there could've been some detonation which would REALLY increase cylinder pressure but since it was a stock ECU there was no way to tell :(
 
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AllanL said:
hmmmm so maybe 7m rods in a 2jz hmmmmmmm gota love short skirts and long rods!
All that would do is raise compression and lower the displacement. Im pretty sure Toyota did its homework on the 2jz and you wount find a better displacement/stroke ratio.
 

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Silver88Turbo said:
All that would do is raise compression and lower the displacement. Im pretty sure Toyota did its homework on the 2jz and you wount find a better displacement/stroke ratio.
BZZZZT WRONG!


THE STROKE DOES NOT CHANGE NOR DOES DISPLACEMENT

The chamber volume and stroke (crank) does

But

what long rods do is change the speed of the piston at the top and bottom of the stroke and also the angle of the rod

as the force from combustion acts on the piston a longer rod helps transfering that force BUT the shorter piston required increases bore wear good for race engine, shit for street engine

Allan
 
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