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Rb26 Rod Strength Settled!

Cateans05

By Cateans05,
in Engines & Forced Induction

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GTSBoy
GTSBoy

This spot reserved so I can come back and say I told you so when the thread turns into a hopeless shitfight.

GTRPSI
GTRPSI

Mercury ran 850hp at all 4 (630Kw) in their R34 GTR on 43 PSI with a stock bottom end from what i remember. They too wanted to find the limit and were expecting failure. Finding the limit is sort of

whatsisname
whatsisname

A piece of string is always twice as long as it is from one end to the middle, unless it's a one-ended piece of string.

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QUP29 Community Regular

QUP29

Posted
Posted

Build engine with standard rods and aftermarket Pistons if that's what you want to do. But be sure to abuse it (and video it) and post back with results(and videos) :)

+1 on video

can't wait to see the photo of this carnage, don't do a half ask job too. i want to see a massive hole in the block :)

Stixbnr32 Rising Star

Stixbnr32

Posted
Posted

I know of a car that ran about 400kw with standard rods for 10 years before they failed. When they failed the ripped in half. But it lasted a long time. I went with brand new rods on my build (nitto's) because they were cheap enough while the engine was apart.

Blackkers Experienced

Blackkers

Posted
Posted

+1 on video

can't wait to see the photo of this carnage, don't do a half ask job too. i want to see a massive hole in the block :)

What do you seriously think would cause that to happen with 450kw and prepped standard rods?

GTSBoy Grand Master

GTSBoy

Posted
Posted

What do you seriously think would cause that to happen with 450kw and prepped standard rods?

Age. It will eventually get any reciprocating part. Prepping standard rods buys you a certain amount of extra strength, and depending on how much effort is put into looking for cracks and so on, a certain amount of confidence that they are in good condition and not harbouring any cracks. But new cracks can form at any time once they've been up and down enough times.

The other killer is of course, rod bolts and the usual risks of being assembled incorrectly.

scotty nm35 Grand Master

scotty nm35

Posted
Posted

I have seen a few built blocks split their bore at not much more than 450kw, personally I would be keeping it as close to stock sized pistons as possible so as not to weaken the bore.

It's not pretty snapping or bending rods, I have been engulfed in the oil fueled fireball whilst standing beside the dyno, I would hate to see the carnage if it happened on the road at full noise for the sake of a relatively cheap set of rods, especially as you have the engine apart...

Why bother at all, just see what you can get out of the stock internals.

scotty nm35 Grand Master

scotty nm35

Posted
Posted

It was a late model 1UZ, light rods known to be undersized for the 1200nm of torque it was putting out. Ethanol was the culprit, along with the GT35 I fitted to it.

The RB26 block split was due to cylinder pressure I imagine, as was the Cossie Sierra race block that did the same thing. Tuning past that imaginary point where pressure beats steel. :P

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scotty nm35 Grand Master

scotty nm35

Posted
Posted

Ethanol produces more torque compared to petrol for similar power, especially when you lean on the boost past where the power stops rising. It is also nearly impossible to find the point where cylinder pressure rises exponentially due to it's anti detonation qualities. At some point some part will let go, where that is who knows, it comes down to your tuner at the end of the day.

If the 1UZ was on petrol, due to being high comp we would have had to stop boosting well before the point the rod went, with less timing. Revs were kept pretty much stock as I remember.

XRATED Veteran

XRATED

Posted
Posted

Just throw a stock rod under a 100lt press and record the pressure it starts to bend at, then do the same for an h beam/forged rod.

Bam...

Stock rod strength question answered!

15deg axial load, I'm going to say..... 3t

J.

Cateans05 Collaborator

Cateans05

Posted
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Posted

Just throw a stock rod under a 100lt press and record the pressure it starts to bend at, then do the same for an h beam/forged rod.

Bam...

Stock rod strength question answered!

15deg axial load, I'm going to say..... 3t

J.

Thats actually quite genius! anyone willing to donate a H beam? lol i got heaaap of spare rods

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