4G93T Rods - Standard V's Forged

[Smutt]

Here are some pictures regarding the two types of conrods for the 4G93T (standard V forged)

Massive difference!!

Here is a bent rod. I pushed my motor progressively.

This is cylinder number one rod, number 3 also got bent.

It only took an extra 3psi to bend it.

I measured the difference between a good one and this bent one (centre to centre), the difference in length was -4mm.

The engine developed a "death rattle", I knew what it was straight away and shut down. After it was pulled down it was found that the counter weight on the crank was hitting and removing metal from the bottom of the piston at bottom dead centre (i should upload a photo of this as well).

I was lucky! This could have been the precurser to sending something out through the block.

Each engine is different. You have heard the warnings regarding the weakness in the rods, now you have seen some pics.

 

[aapje]

So how much PSI were you running at the time it went bang?

 

[wilbagsr]

At least you'll have a tough new motor though hey!

 

[thirteen]

Damn that is a huge difference.
What were mitsu thinking with such skinny rods?

 

[Missile]

Damn that is a huge difference.
What were mitsu thinking with such skinny rods?

Lighter rotating mass, more responsive etc.

 

[thirteen]

Lighter rotating mass, more responsive etc.

Makes sense.

Does this mean GSR's with forged rods aren't as responsive?
Just curious.

It only took an extra 3psi to bend it.

Did you constantly rev it hard, it's just that I thought it was revs not boost that kills 4g93t's.
Especially with only 3psi extra.

 

[Entaran]

You're talking about an engine that was manufactured and finished design in 1991. They would've designed it to the best of their ability back then and indeed the rods have held up to the test of time. Give them some credit where credit is due, 90%+ of GSR's would never have been modified beyond an exhaust and light intake mods if at all. You can STILL find unmolested ones with relative ease.

 

[Smutt]

I know this is against the odds but this is what I ran....

was running 20psi for over 2.5 years on standard rods...
Turbo on it (at that stage) could not sustain 20psi over 6000rpm, so gear changed at 6000rpm, except when in fourth gear (held revs higher)...
by no means did i baby this motor!

breaking point was 23psi, almost straight away...

again I will stress not to expect your motor will hold 20psi, dont!
research will find that this is too high...

But hay... i had fun pushing it....

 

[boostboy76]

The rods can't be quite the horrific toothpicks everyone makes them out to be if they could withstand 2.5 years of hard driving running over twice the factory boost level.

I don't reckon too many factory built engines would stand up to being run at over double the designed boost for that amount of time without something giving.

 

[thirteen]

When Smutt said an extra 3 psi I thought he meant
an extra 3 psi over the standard 10 psi...
Not 20 psi + 3 psi!

 

[3zercrowd]

Meh..... I await the day I have to call a flatbed because I broke the $200 engine:lol:( Forgie come on down)
I have more to fall back on
See my dyno sheet in my members rides for the boost:thumbsup:
Although it doesnt get revved past 7000:lol:

 

[Entaran]

I hit 8700 this afternoon in my 63...

Logs show nothing wrong either WOOT.

 

[blackers10]

my white gsr had been running 20psi for a fair few months before i got it and then it overboosted and let go(pretty sure that was the cause)

the only thing id be worried about is forged H beams will SNAP where as I beams will bend THEN snap so you know its comming before your motor becomes swiss cheese

 

[CLuTZ]

I hit 8700 this afternoon in my 63...

Logs show nothing wrong either WOOT.

Why you would rev your motor out that high is beyond me...... Your turbo would have run out of puff after 7500. Lets not clog someone else thread up though, right? Right.

 

[wilbagsr]

Either way here guys, the simple fact is which ive said in many threads, the 4G93's are a tough little motor capible of big hp if built correctly. Every engine has a breaking point and clearly in this case, it's thrashing the pants off this thing for 2 years, then cranking the boost that bit too much. With a strengthend bottom end, he can quite confidently use alot more boost than what he was and as i did with Johns old engine, ran 26psi as a daily driver. Good fun too. :thumbsup:

 

[Smutt]

the only thing id be worried about is forged H beams will SNAP where as I beams will bend THEN snap so you know its comming before your motor becomes swiss cheese

Im not worried about my conrods now... bring it on...

Forged: "H" Beam conrods or "I" Beams for that matter... failing under excessive load without detonation issues... I would like to see that :thumbsup:

Anyone had a forged conrod fail in a 4G93T and/ or got a picture to upload as well?

 

[wilbagsr]

Im not worried about my conrods now... bring it on...

Forged: "H" Beam conrods or "I" Beams for that matter... failing under excessive load without detonation issues... I would like to see that :thumbsup:

Anyone had a forged conrod fail in a 4G93T and/ or got a picture to upload as well?

lol... highly doubt it! But let the sceptics pass judgement.

 

[Smutt]

As promised.... photo of the damage to the underside of the piston...

 

[blackers10]

well in the end.. they all would fail at their own point.
has anybody found the breaking point of the forgies.. if not. why not?

 

[GSRWRC]

Anyone had a forged conrod fail in a 4G93T and/ or got a picture to upload as well?

Mate of mines after the oil releif valve stuck open mid run.

Currently the worlds fastest 4G93T GSR 9.25 @ 153mph