What kills a 4g93t?

[Dave_GSR1.8]

So, just wondering, what causes the rods to go on a 4g93t, is it too much boost, or too much power ?

ie if you keep the boost at 15 psi (for example) but have a bigger turbo with supporting mods, so you can make more power, at what point do you start running the risk of engine failure? Could you get to 150kw atw (reliably)? Could you get to 160kw atw ? I know it depends on how good the tune is so lets assume you have a good tuner, you keep boost at around 15 psi and you can keep inlet temps as cool as possible, so only power is going up (by virtue of more air/fuel being pushed in because of a bigger turbo, bigger injectors etc) and not boost pressure.

If you wind up boost to, say, 20psi (on your bigger turbo) you will make a lot more power (presumably), is it this increased power that breaks a 4g93, or the fact you have much higher pressures because of the increased boost ?

I'm not sure if this sounds terribly coherent but I'm interested if anybody has any thoughts, as I'm going to add a bigger turbo to my stock 4g93t and I recall seeing a thread about this which I now can't find (it may have been a throw away line in a discussion about something else). I know I can get some more power, just curious about the limits.

Thanks in advance for any feedback

 

[captainTeeBag]

What causes them to go is the fact that standard rods are as weak as piss.

 

[khubner1]

quite simply it's torque too much torque will bend those rods.

incase your wondering heres what 4g93t rods look like

they're an I beam rod (not the best when a torque load is horizontal to the flat (skinny) portion H <-load

now compare that to every aftermarket forged rod out there and you'll see the difference in strength

 

[Dave_GSR1.8]

Yes, I get that impression!

From what your saying Khubner its power (torque X revs ?) that kills them (rather than straight out high boost) ?

So what can I get away with ? I've seen someone say they had 163kw atw (I think on a stock GSR), is that optimistic ?

 

[khubner1]

mine ran 138 on around 15psi fwd.

it's not so much power but torque combined with load and stressing the rods. most report have the rods letting go either in the low end or right up high in the range. where timing is very well advanged and the rods are copping the highest amount of stress

 

[Dave_GSR1.8]

Hmm, looks like I am going to have to contain myself as I can't afford a forged 93t or a conversion at this stage, maybe in a few years time...

Anybody got a spare surplus forged 4g93T.... ?

 

[khubner1]

you got a crank a turbo an exhaut manifold sump etc then yes i do.

 

[4piknup]

Just put rods in it

 

[Dave_GSR1.8]

Found this thread,

http://www.4gtuner.com/topic/14331-4g93t-rods-standard-vs-forged/

Lots of interesting info.

And khubner, now you say you have forged rods, pistons, block...

Gotta love this site...

 

[khubner1]

There's was nothing wrong with my rods/engine I spun a harmonic balancer

I've seen a 93/92 frank engine throw rods this the forged build for the new engine else it'd probably be running those same toothpicks

 

[3zercrowd]

Mine had over 200+ for ages on the stock bottom end before it let go (driving really easy by the way) driving the kid to daycare.
I was running up to 22psi the whole time on a big 16g then 20g.....

 

[Dave_GSR1.8]

Yes, I read your build thread, it gave me the confidence I could get a little more out of my stock bottom end (currently 131 kw atw) but you know what your doing, I don't, so I won't push quite as hard!

But, the more I read the more I think I can crack 150+; assembling the parts now, almost have everything I need... Jamo is sending me broke.

 

[khubner1]

mine had 138 fwkw on i think 15psi (clutch was slipping and it was getting alil lean up top (think i was running a the td05 for the power runs on the std untuned gsr ecu with an evo ecu injector and afm ont he same boost i suspect you would see mid to high 140's)

 

[Dave_GSR1.8]

Yes, thats what I am hoping, you were getting more than I am now with your bigger turbo, but other items standard; once I have the bigger injectors, AFM, bigger turbo, (maybe a fuel pump) and with my current mods, I'm aiming for +15 to 20%)

Still six months away, few other things to sort out first.

 

[khubner1]

i think 20% is alil optimistic

 

[evo-gsr]

I dont...my maths works out 20% increase over 131 to be around 26kw....why is that optimistic?

 

[Dave_GSR1.8]

I'm always an optimist!!

However, having read the forum a fair bit I get the impression that my target is not out of the question. If Dane was getting 200+ atw, on up to 22PSI, I'm hoping I might get 150+ on 15psi. I also figure that if you were getting 138kw on a bigger turbo and not much else, with all my mods (which includes a bigger turbo), I'd like to think I can go a little better.

Now this is all guess work, but I was happily surprised when I got to 131 on just a chip, exhaust and FMIC, so I am thinking I might be happily surprised again!

I hope so, its part of the fun!

 

[evo-gsr]

I think you will get the gains you predict Dave. My comments above were directed at Hubner as I think he is incorrect in saying 20% is optimistic.

 

[4piknup]

Awd chews more power than fwd. It may rip 8-10%

 

[khubner1]

And the number in quoted was when my car was still fwd