Block casting

[GavinT]

Finally started to assemble my 88 engine. Using other peoples threads for reference, inspiration and comparison ( one of the great things about this forum ) I couldn’t help notice the quality of the castings.

Comparing these two blocks, one is mine (bottom) and the other is Ian’s - chillidoggy. You can clearly see mine is so much rougher on the inside. If you look at #4 on my block it almost looks like the liner is not seated correctly but it is. The casting is just not uniformed across the block. There is much more material around #4 which is giving the visual impression that the liner is not fully seated. Looking at Ian’s the liners all look seated equal and the general appearance is much smoother and machined better. Almost like mine is a Friday casting and Ian’s was a Monday morning.

I guess Lotus changed the process or supplier. 

[jonwat]

Looks like your block is sand cast whereas Ian's is die cast 

 

[drdoom]

It is true that Lotus changed the block casting well on in the production life however the sump area casting finish is the least relevant aspect of the upgrades. Thanks for sharing, it's true this forum is a great resource for the dedicated owner.

Cheers

[snowrx]

Can anyone enlighten me on the use for the #4 water jacket plug that was deleted on the later block?

[Cliffords]

If you clean that lower block in a hot bath of brick cleaner /mortar remover for about 20 mins it will come out smoother . Don't ask me how I know.  This is not a recommendation on the block , I did it on some parts, water pump etc and the difference is astonishing .   If you leave it too long it will disappear I expect .

[Chillidoggy]

I had all the alloy engine parts vapour blasted, which would account for the shiny finish on them.

It may be that there were various revisions to the 910 block as time progressed and power outputs rose. Castings have to have holes so as to remove any sand used in the casting process. These may later be used to accommodate core plugs, or tapped holes for oil galleries etc. I'm not convinced that my block is die cast, though. That's an expensive way of doing it, and not usually worth it for low volume production. But as always, I stand corrected.

[Steven162]

None of the blocks were die cast

[drdoom]

Elsewhere I've read that use of caustic chemicals on AL components must be done with great care, if at all. Believe @Cliffords to be correct in that pieces will dissolve if left exposed for too long. Also note it is important to neutralise the chemistry once done with cleaning by treating the alloy with vinegar or the like before final rinse with water. 

[Cliffords]

I have also experimented with Vinegar on steel components as rust removal. I left the oil pump drive in and forgot it and it's totally had it . The whole surface has desintergrated.  Good fun this home experimentation.😄