Td42 Silvertop engines

[Michael]

Ok so there has been quite allot of discussion about the elusive Silvertop engines with no one really knowing how to identify them or what exactly makes them so special.

Over the last two months I was abke to strip down two Silvertop engines and was able to see exactly whats on the inside

Interesting finding....... the first one was in a import GQ shorty and had a vacuum pump on the alternator with a silver rocker cover.
Now the next silver top came out of Tommy Jr's GQ and has a vacuum pump under the diesel pump with a regular alternator and a black rocker cover (looks just like the engines in the GU)

Internals......... well this is where I was most interested to see what the fuss is all about and indeed the pistons are different to all the other NA engines I have opened.
It is more beefy than the NA pistons, has a 28mm gudgion pin vs the 30mm of the GU black top and if I have to compare it to something, it looks exactly like the proper TD42ti pickup pistons but without the cooling channels in the piston head.

This was the one ans only difference I could find between the NA TD42 engines

Will post some pics later

[Alex Roux]

Michael

Given the differences between the two engines you mention above, what is it that makes them “Silvertop” to begin with?

[Rudolph]

Interesting Michael, should we compare the pistons you took out with the 28mm gudgion pin, with the one's taken out of mine recently also 28mm? When I picked them up compared to the TD27t pistons I replaced it with it did feel much heavier.

Did both the engines you worked on had the VE pumps?

I have also noted a "K2" marking on my engine block with other TD42's with "K3" marking, not sure what this means

[ricster]

Quote....( Interesting finding....... the first one was in a import GQ shorty and had a vacuum pump on the alternator with a silver rocker cover.
Now the next silver top came out of Tommy Jr's GQ and has a vacuum pump under the diesel pump with a regular alternator and a black rocker cover (looks just like the engines in the GU)).
I would say that the second TD42 motor in Tommy Jr's GQ is actually a "black top" TD42 motor as you mentioned the black rocker cover and not a silver top ( not sure if is was a typing mistake), and the location of the vacuum pump ( being for me the deciding factor ). My 99 GU model has exactly the same setup as Tommy Jr's GQ model, with the 30mm gudgion pins. If I recall yours are also 30mm in your motor. So in my opinion, in a nutshell, if the vacuum pump is on the alternator, you have a silver top.... vacuum pump under the injector pump, then that's a black top.

[Michael]

All I can find different is the pistons in the silvertop. All ellse is exactly the same, so I guess thats what the fuss is about

Cedric as mentioned above the black top in Tommie's car and the silvertop import were identical inside except for the tappet cover color and vacuum pump location. Both have the same pistons and both have 28mm pins.
This confirms what I thought originally that its quite a mix and match.

[Michael]

Interesting Michael, should we compare the pistons you took out with the 28mm gudgion pin, with the one's taken out of mine recently also 28mm? When I picked them up compared to the TD27t pistons I replaced it with it did feel much heavier.

Did both the engines you worked on had the VE pumps?

I have also noted a "K2" marking on my engine block with other TD42's with "K3" marking, not sure what this means

Rudolph, as fas as I can see and have read there is abselutely no difference between the engine blocks of ant of the TD42 engines regarding strength and the same goes for the cylinder heads.

Please give feedback as soon as I post the pics of the pistons so we can check if you also maybe have a silvertop

[ricster]

Michael, yeah absolutely agree. many years back when I redid my motor I said exactly the same, that I believe here in SA, we got some of the scraps before the ZD30 was launched here in 2000.

My motor and Tommy Jr's motor are identical, except for my motor having 30mm gudgeon pins. Even Frans at the time, who was giving me loads of help and info, said I was lucky to have the 30mm gudeons and not the 28mm. I assume 30 is better than 28mm. Were yours not also 30mm in your TD42?

So yeah all the leftover bits and pieces were put together to make a few TD42 motors and sent through to us.

Is there a difference between the TD42Ti head and the TD42 ( either silver or black top ). When I did my motor, I was told that they are not compatible. I wonder if they improved the cooling layout/flow slightly inside the TD42Ti head

[Michael]

Cedric yes mine also has 30mm pins like yours.

Tommie Jr also has a silvertop engine so his are identical to the silvertop from the shorty. Both have identical beefy 28mm pistons which I have never seen before.
I have stripped a couple of GQ engines and even David V's pistons are identical to the TD42 GU engine's pistons apart from the 30mm pins

The cylinder heads actually are identical, but the precoms are not the same, which is aparantly the only difference.

Below are some pics of the pistons
From left to right, NA black top 28mm and 30mm piston, TD27 30mm turbo spec piston, 28mm silver top piston, 30mm TD42TI pickup/ud40 piston

Pistons lineup

IMG-20171019-WA0014.jpg (91.27 KiB) Viewed 8962 times

Top view of the silver top on the left and the TD42TI piston on the right

Top view

IMG-20171019-WA0013.jpg (117.63 KiB) Viewed 8962 times

Side view of the silver top left and TI on the right

Side view

IMG-20171019-WA0015.jpg (87.5 KiB) Viewed 8962 times

So if you look carefully, the silvertop and the TD42TI piston looks identical except for the 28mm pin and the cooling ports in the piston head of the TI

[Michael]

So the only reason I think the silvertop is so popular is because from all the NA engines this ons has the strongest pistons and will take the most punishment when a turbo is bolted on.
Its unknown if the piston has the alfin incerts in, but I suspect they do.

They will obviously not be able to take nearly as much punishment as the TD42TI pickup engines, but is the secons best standard engine out there

[ricster]

And the rest of the TD42Ti motor compared to the TD42? Where is the extra beefiness to allow more power? Are the Conrods different? I assume the crank is identical, or are they also different?

Interesting to see the piston pics of the difference.... or lack thereof

But I'm going to disagree with you though on Tommy Jr's engine. That is a black top in my opinion but with 28mm gudgoens, purely due to the vacuum pump position. I believe its not so much the 28 or 30mm gudgeons that determine the black/silver top type, but more so the vacuum pump position. That is the way to see when that motor was updated from Nissan irrespective of if it was in a GQ or a GU. I again believe that even the crossover from Silver to black top, there was a mish-mash of parts hence some having 28mm and others 30mm gudgeons.