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Discussion Starter · #1 ·
I am sure this can't be new ground here...Who has done this? I figure a good second hand GEMS 4.6L out of a early P38 would be a direct swap into a 4.0L D1...Or, 4.6L crank and pistons in a 4.0L block...I want to build a engine to keep as a spare and I sure do not want to throw the same dismal power/mpg engine back in...If gas it had better go or diesel-better mpg.....I have heard about a 4.6L pursuit engine, but no idea where to source one. I am in the middle of swapping a R380 in my ZF truck and wanting to do the 300tdi/R380 swap in the other truck...I do nto need three of the same truck....options???
 

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I am in the process of dropping a GEMS 4.6L into my Disco 1 97. I got a used 4.6L GEMS and tore it apart replace all the bearings, regrind and polish crank, new piston rings, minimum hone cylinders, valve job, redecking block and resurfacing the heads, cam shaft, cam bearings, lifters etc.

I recommend getting a 4.6L motor rather than getting the crank and piston rod from a 4.6l into a 4.0l

The blocks are the same, but the quality in the 4.6L is better. When land rover receive the engines they are rated on quality and the best are reserved for 4.6L and 4.0L are the lower quality. Source How to Power Tune Rover V-8 Engines: For Road and Track - Des Hammill - Google Books

I would only obtain the 4.6l crank and rod if you can't locate a complete 4.6l engine.

The 4.6L pursuit engine is great but it is way to pricey. Depends how much you want to spend obviously.
 

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Discussion Starter · #3 ·
I would start with the complete 4.6 short block...There is not a difference in quality between the 4.0L and 4.6L... The castings equally suck and if anything, the 4.6 is more prone to sleeves failing due to the thin walls to accomodate that were not much of an issue for the smaller bore 4.0L...4.6 also had porousity issues and lest we forget, the famous oil pump housing alignment dowel pin that thousands were not set into the block/aligned correctly and they subsequently machined themselves to catastrophic failure. As the castings went on, they got dirtier and dirtier and with the 4.6 being near the end of the line for this block, they are some of the worse, hence the high failure rate of head gaskets and liners. The casting quality is so bad LR nearly gave away all of their extra stock as no one wanted to buy them. History if this whole issue can be found from Cosworth who is recasting the 4.0L/4.6L blocks. These are the ones you want. I would, however, for the price, throw in a 4.6 GEMS engine from a P38 complete if it had good compression and around 100k as it should have had it's teething issues sorted by then...hopefully... I have several 4.0L and a 4.6L not bashing, 4.6L pulls very well, but it is not without it's own issues. Just wondering thoughts on using it in the D1... I am sure it has been done.
 
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