GQ v GU N/A Diesel engine mechanical differences?

[Antpenny]

Hello can anyone tell me the mechanical differences between the GQ and GU 4.2 naturally aspirated Diesel engines? I'm being told the GU's are stronger but I thought that they are exactly the same block and internals? If they are different can anyone detail what differs between them?

[Antpenny]

Sorry to be more specific It's a 97 GQ engine v 2001 GU engine I'm curious about?

[Dales300exc]

Pretty much identical if both N/A

[Antpenny]

Cheers mate that's what I thought but my mechanic is trying to convince me otherwise?

[93patrol]

There are differences to the black tops and silver top (rocker covers). Aparently the silver tops have stronger internals

[Antpenny]

Yes I believe the silver tops where mid 93 and of similar specs to gu turbo engines but the naturally aspirated donks post 93 to the GU n/a units or black tops are the same Mechanical specs in all aspects I thought?

[Dales300exc]

Silver tops, N/A blacktops and factory turbos are all different internals.

[Antpenny]

Could you elaborate on that mate? I'm confused...I'm aware turbo engines have heavier pistons and perhaps the gudgeon pins differ also oil squirters but gu and gq n/a are identical right?

[BigRAWesty]

As far as I know the only part which is heavier is the crank.
So the early model had bigger bottom bearings on con rods, and I've seen bits about oil sqirters but unsure on that.

To the best of knowledge piston sizes, stroke length etc are the same.

The factory turbo motors I've read ran decomposition gaskets..

So what are you looking at doing?? A rebuild?

[Antpenny]

Yes mate I'm looking at rebuilding the GQ n/a engine but want to rebuild it with all the heavier internals of the turbo engine and wind the boost up to 12-15psi if that's possible?

[Dales300exc]

N/A silver tops and black tops both had 28mm gudgeon pins, some reports say black tops had no squirters(can not confirm) silvers definitely do have squirters. Pistons are different in black tops and gear driven vac pumps as opposed to alternator vac pumps on silver tops. 86mm flywheel boss and smaller harmonic balancer.

Factory turbos are a whole new kettle of fish. 96mm flywheel boss and larger balancer. 30mm gudgeon pins and crown cooling through the crowns. Larger rotors on the oil pump. Different pre comps in head. Squirters much longer too.

As far as main and big end bearings, they are all the same size.

Compression ratios are very close across all engines (cant remember numbers, around 22:1 ring a bell)

[BigRAWesty]

Don't worry about it mate. Both versions have proven themselves to be extremely reliable running those pressures.