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  1. #11
    Join Date
    Apr 2004
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    on the edge...almost falling off
    Age
    56
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    8,518
    This should get some interesting replies but I didn't think the cracking blocks/slipping liners was a defect? I'm led to believe that RR ran the ecu too lean for emission purposes which caused overheating and the problem as stated? One of the reasons why Sidecar runs a cool engine (I do too but for different reasons )!!
    BIG TONE


    Mercedes SL owner, definitely NOT a kitcar owner like you lot!


  2. #12
    Join Date
    Jan 2006
    Location
    Chadderton, Nr. Manchester
    Posts
    1,902
    I don't want to take the thread too far off track, but Rover measured the wall thickness of the blocks and colour coded them to identify which were the best. Overheating seems to be the trigger, but on a badly cast block, this is where the water jacket leaks, and the liner slips, then oil mixes with water... as I found out

    In my eyes, if Rover knew of the likelihood of that happening, then that is a (latent) defect - I've had mine fixed at Turner Engineering (at a cost of almost a grand!)

    Jon
    Oh crap...the wife has realised there is no such thing as a 5 minute job !

  3. #13
    Join Date
    Mar 2006
    Location
    Location Location is a crap TV program
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    8,042
    My understanding is that it was a combination of things that caused the problems:-

    1. The moulds were getting old which meant that the wall thickness between the liners varied from one block to another, I guess at some point the ali wall thickness became too thin to cope with either the thermal stress and the mechanical stress so it cracked. The length of the head bolts has also been cited as being part of the problem, the cracks seem to appear at around the same depth as the end of the head bolts.
    2. The liners on some blocks were not pushed fully down and held down into the block as it cooled, this meant that they lifted up out of the block as it cooled. When the block was in service that only friction held the liners in place, if they had bottomed out then they would have been held in place by the heads.
    3. The Range Rover ran the engine hot, probably hotter than it was designed to run at, something like 96 degrees. This would be OK if the engine was designed from the outset to run at this temperature like many more modern engines but I don’t think that is was the case for the RV8. The heat and the lean mixture I guess was meant to keep the CO in the exhaust low. (Although other nasties actually go up with heat, I suppose the CAT would deal with them). Basically a two valve open wedge head with poor squish is not going to be all that clean in terms of its exhaust gases.
    4. The liners were pressed into the blocks when the block was at about 150 degrees C, as the RR ran the engine at over 90 degrees C this was not all that far off the temperature that the liners were fitted at, the liners could become loose and ‘float about’ in the block.
    5. The RR had a setup where the thermostat was in an odd place and this may have caused some overheating problems
    6. The RR had issues with the top hose, it would split and then dump all of the engines coolant on the road, no engine would like that sort of treatment


    From memory the 4.6 lumps were not reported as being the worst engines, I think the 3.9 lumps and the 4.0 were worst but I could be wrong here!

    I think that if you do find an engine that has not cracked or dropped a liner then it won’t do either of these things if you run it fairly cool and with a decent AFR ratio at any time that it’s is under load. (On cruise you can run it as lean as you can get away with whilst maintaining good throttle response).

    I also think that if you are going down the route of building a ‘hot’ engine then you would be a bit mad not to start with the largest ‘off the shelf’ engine that you can get hold of. It will cost you a bit more for the actual engine but all the other costs such head work and machining are the same.


    Having said all that one thing is not to underestimate the work here, look at Benjai’s thread and he has not even got to the point of building the engine yet! Of course you do not have to go to these lengths but if you want 300 BHP out of it then really it all needs to be right, for example an Offy dual port won’t flow well enough and will knock off the top end. (Sorry Robin66 but its true!...In fact V8 Developments would only sell me a really mild cam for a 3.9 lump I was working on because it was going to use the dual port, in the end we ditched the manifold so we could fit a decent cam).

    All of the above is just stuff that I’ve read or been told about, some of the detail maybe a little off, if so please forgive me!
    Last edited by Sidecarbod; 17-10-13 at 11:13 AM.
    I refuse to engage in a battle of wits with an unarmed opponent.


    Rules for buying 'Go Faster' parts:-

    If it's fast and cheap then it's not good.
    If it's cheap and good then it's not fast.
    If it's good and fast then it's not cheap!

  4. #14
    Join Date
    Jan 2008
    Location
    UK
    Posts
    780
    ...as Pete says, as soon as you start mixing and matching parts, it soon becomes a lot of work. If it were me, I'd try and find a decent complete 4.6 as a base unit - that way you know all the parts are compatible - then you can just replace the front cover with the SD1 item and the few other usual mods. I think that you can now get over-sized main bearings etc for the 4.6 crank, so the rebuilding should all be fairly straightfoward.

    If you want some real fun, try building a stoker 351c engine in the uk in your garage - I've now spent about a week trying to find suitable valve springs! That's before all the other fun of figuring out a workable CR with the heads and pistons I have (never change your plans mid way though..), selecting and obtaining the right valves, and getting the quench to work with the available head gaskets... It's given me an appreciation for why engine builders charge a decent rate for their work, and also totally disproved the myth that Yank engines are cheap to build!!
    Crendon CR427 No. 55

    I remember Kaase saying to build a 400+ HP Cleveland you "use good parts and then starting pulling plug wires 'till you get there"...

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