Forged internals longevity?

[blink]

I've had lots of mixed feelings about how long a fully rebuilt (bottom end) motor should last...
Considering you are running conservative boost?

Like can I expect more than 5000? more than 10000? Lots of people sell them not long after rebuilding?
Are they scared theyll blow?

[Phillyb]

cant see how they would only last you 5000 kms unless you're going to be bagging the absoloute shite out of ur car at all times. ive got 40,000 kms on my forged bottom end and the first thing to go was the bearings.

[h4X6]

40000 km isn't that much. Especially with the amount if money forged costs.

I'd be interested in this answer too... I would expect forge to last a hell of a long time.


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[gtrjon]

man come on guys. the longevity of the motor has nothing to do with the material of the bottom end components. WAY WAY too many variables to say o if you have ___ pistons and ____ rods you will last 37598kms. like anything else in the world not just the automotive industry. if you spend good money have good work done and you treat it properly it should last longer than you will ever own the car. of course people rape on their cars with half assed work so they dont last. /thread

[coston]

man come on guys. the longevity of the motor has nothing to do with the material of the bottom end components. WAY WAY too many variables to say o if you have ___ pistons and ____ rods you will last 37598kms. like anything else in the world not just the automotive industry. if you spend good money have good work done and you treat it properly it should last longer than you will ever own the car. of course people rape on their cars with half assed work so they dont last. /thread

Sums it up perfectly

[blink]

Thank you, sorry I just like to see what people have to say about it.

I'm just always sketched out it won't last even if I use it just for cruising, maybe bring it up to 6rpm every once in awhile,

I see so many gtr's for sale with descriptions such as "only 5000 on rebuilt motor" etc etc and it makes me feel like spending 9k on this motor won't be beneficial. I know it's just a dumb worry because my motor ****** up after buying it and driving my car for no more than 300 km,,,,, three hundred =p ..=[

[Skym]

Like said above it depends on how you drive car. Also if car has the mods to make engine survive a thrashing.

Wet sump race engines (V8 or import) are routinely rebuilt every 3000-3500kms. But they are thrashed lap after lap.

If on racetrack with high G corners, oilpressure can drop on high G corners and lose a engine with wetsump setup. That's why dry sump is must have on racecars when running quick laptimes with pro driver or drive slower around corners to keep the G's down if have wet sump setup. If drive slow around corners on trackdays with oil restrictor, sump, cooling, etc mods and drive on road most of time, 100,000km can be achieved.

Also warming engine up before thrashing car helps to get oiltemps up, forged pistons have expanded enough, etc. Cold, thick oil fails to get to bearing surfaces at higher rpm's, so thrashing a cold engine is not a good idea. Also oil getting too hot, breaking down causes bearing failure (need a engine oilcooler).

[blink]

Thank you once again skym, just looking for some number like that under regular driving, I won't be racing. This car is to cruise around in.

Basically should it last as long as stock consider you treat it like a stock, you know

[Skym]

I know of one stock RB20DET engine that has done around 250,000km before bearing failure and that's with 100hp above stock hp (max you would want to push stock RB20, RB26, etc engines if want longevity). But usually racetrack is where it fails (I assume oil pressure or oil temperature problems). You can fit an accusump to help with stopping drops in oilpressure (popular mod on RB engine for racetrack, drag strip if not running dry sump setup). Engine oilcooler + oiltemp gauge helps to monitor, keep oiltemps under control and running correct oil for clearances, oiltemps (monitor oilpressure).

It's recommended to rebuild engine every 100,000km if it has been reved. Mainly the head is where it goes wrong (worn valvesprings, leaking valve seats, etc).