c21vhpd Posted June 21, 2003 Share Posted June 21, 2003 What are peoples experiences with Accralite pistons in K engines? I recently, with Johnty Lyon's help, rebuilt my VHPD and we fitted Accralites as that was all I could find in stock at the time. Since then my oil comsumption has been high - (1 litre per 1000 miles I would estimate). I didn't actually realise how high the consumption was until I saw my OP gauge bouncing off 0 on a roundabout, after which I found myself putting in 1.5 litres of oil... I fear I was too negligent though, as the engine is making definite 'shot bearings' sounds ☹️ So, as I'm going to taking the engine out anyway, does anyone have a few words of advice as to what to do about the pistons. I'd prefer to keep hold of them, as they seem otherwise to be a good design. Miraz and Mick Smith have reported similar symptoms, although they are running their engines at a much higher CR than me (in mine the Accralites give a CR of 11.3 vs the normal VHPD CR of 10.5). Mick skimmed his pistons by 0.012" and reckons that helped. So I could skim mine too, but is the difference between 11.3 and 10.5 CR really enough to give this level of oil consumption problem? Honda Passion Orange, 640kg , and proud of it Link to comment Share on other sites More sharing options...
16vastra Posted June 21, 2003 Share Posted June 21, 2003 i have heard off accralites being difficult...something to do with the way the block needs to be rebored which isnt per the instructions! dont know the specifics, but i am getting some in a few months cheap cos the guys not happy with them. it involves there not being a proper seal and oil burning (not that i see how unless the rings are crap) Link to comment Share on other sites More sharing options...
Casbar Posted June 21, 2003 Share Posted June 21, 2003 I have Accralites in my Xflow, and yes forged pistons do use oil, but the rings are fine and the oil consumption is no more than I would expect from a tuned engine Link to comment Share on other sites More sharing options...
Jason Plato Posted June 22, 2003 Share Posted June 22, 2003 I have accralites , originally I had them fitted in my original block with brand new Rover liners . Oil consumption once bedded in ( 700 miles ) was very good , whilst they were bedding in I expect I used 750ml . Then I used maybe 350- 500 ml during a trackday , which I believe is very good . last winter I fitted a Scholar race engines liner set up , this conversion is hot honed and new rings were fitted , the finish on the honed Scholar liners was stunning , not *quite* as fine as the original rover ones but bloody good none the less . Oil consumption during the first 750 miles was again about 750ml now 2000miles later the engine uses virtually no oil , my losses are from topping up and spit back into the catch tank . On track I probably use 250ml during a typical day . The compression ratio on my engine is also high , but this doesnt appear to be a problem . I would have thought that the honing of the liners and initial running in period was the most crtical . Dave Edited by - Dave Jackson on 22 Jun 2003 07:22:29 Link to comment Share on other sites More sharing options...
Jason Plato Posted June 22, 2003 Share Posted June 22, 2003 maybe try a compression test ? Does the engine breath heavily into the catch tank ? Link to comment Share on other sites More sharing options...
c21vhpd Posted June 22, 2003 Author Share Posted June 22, 2003 Compression test is definitely the next step. How do youy define heavily? There's noticeable movement of air in and out of the catch tank - enough to feel on your face from a few cm from the catch tank vent. Honda Passion Orange, 640kg , and proud of it Link to comment Share on other sites More sharing options...
Roger King Posted June 22, 2003 Share Posted June 22, 2003 Bore finish in my opinion is the most important factor of all in an engine build. The Accralite rings are very sophisticated, but need a plateau honed bore finish. This is way beyond the sort of finish that can be achieved with the sort of honing stones that some reconditioners use. The difference isn't really visual, so you have to be able to trust the machine shop on this. I assume that you did re-hone the bores or fit new liners. The standard Rover finish isn't that clever in my experience. Compresssion ratio isn't really a factor in oil consumption. Link to comment Share on other sites More sharing options...
c21vhpd Posted June 22, 2003 Author Share Posted June 22, 2003 New liners were fitted and honed, but I don't know by whom or how they were honed. I'll find out. Honda Passion Orange, 640kg , and proud of it Link to comment Share on other sites More sharing options...
c21vhpd Posted June 24, 2003 Author Share Posted June 24, 2003 I've talked to Alan at Scholar. He reckons that plateau honing is only really used to ease the bedding in of the piston rings, but once they are bedded in there is essentially no difference. I'm not completely inclined to agree having read around a bit on the web (e.g. here, but I'm prepared to conceed that he has more experience than me Scholar's solution for VHPDs seems to consist of using a different block (Lotus Evo 4 I think he said) into which they can interference fit liners. The block is stiffer and the pretensioning by the liners gives further stiffening, to reduce oil loss in higher rpm engines. Not only that, they use their own liners as they too often find that the standard Rover liners are already at 80.0mm before they start honing them. Alan hinted that that's not the be all and end all of the issue of oil loss in VHPDs so, I'm going over to Scholar on Thursday morning to chat and find out what's what. I don't fancy a new block, but may get myself a new set of liners. Honda Passion Orange, 640kg , and proud of it Link to comment Share on other sites More sharing options...
scooby dooby doo Posted June 24, 2003 Share Posted June 24, 2003 I thought DVA had some omega pistons going begging.... 🤔 HOOPY R706KGU Hoopylight R Link to comment Share on other sites More sharing options...
Jason Plato Posted June 24, 2003 Share Posted June 24, 2003 C21 They are good people at Scholar , the conversion you described is the one that I had dave Link to comment Share on other sites More sharing options...
c21vhpd Posted June 24, 2003 Author Share Posted June 24, 2003 Thanks Dave... Hoop, the Accralites are so much nicer a design than the Omegas that I can't quite convince myself to change them. The rings are better and the arrangement for attaching the con-rod too. And they have that groovy little dangly down stalactite bit for dripping oil into the little end as well Whether or not it's worth it given that they need a stiffer block to run in is an issue that's troubling me though Craig Honda Passion Orange, 640kg , and proud of it Link to comment Share on other sites More sharing options...
scooby dooby doo Posted June 24, 2003 Share Posted June 24, 2003 Any pictures showing these groovy bits 🤔 And whilst they are 'better', the omega runners all seem happy and the accralite people have had problems.... HOOPY R706KGU Hoopylight R Link to comment Share on other sites More sharing options...
oilyhands Posted June 24, 2003 Share Posted June 24, 2003 Omegas can be fitted interference (yuk) or fully floating to the rods, the dangly down stalactite bit gets in the ****** way when fitting Accralites to standard pattern rods, it needs to be removed with a carbide cutter. The correct plateau honed finish is absolutely vital , I always rehone any liners supplied from the factory. Oily Link to comment Share on other sites More sharing options...
c21vhpd Posted June 24, 2003 Author Share Posted June 24, 2003 Johnty used a pair of pliers to break the end off - a bit more violent, but cleaner! I hadn't realised that the Omegas could be used fully floating. If the problems with the Accralites are related to stiffness of the block/liners then presumably the rings on the Omegas are a little more flexible so they can conform to the distorted shape of the liner a bit better? Is there more to it than that? Honda Passion Orange, 640kg , and proud of it Link to comment Share on other sites More sharing options...
Johnty Lyons Posted June 25, 2003 Share Posted June 25, 2003 I'm using Omegas in my 1.8DVA I've just [ before LTL] done a strip down removed and refitted the liners and changed the rods to Arrows I did not rehone [naughty I know ;-))] However 2000 miles later I still have ninimal oil consumption I somehow don't think I'd have got away with it using Accralites, jj Link to comment Share on other sites More sharing options...
c21vhpd Posted June 27, 2003 Author Share Posted June 27, 2003 Just back from talking to Alan at Scholar. These are the facts as I understood them. For beefing up the cheesy K they do 2 conversions - the Evo 2 and the Evo 4, both Lotus designations. The Evo 2 is a normal K block, machined out a bit to accept thicker liners. The liners are oversize, and are fitted into the block after it's been heated to some reasonably insane temperature, so that the block gets a nice compressive loading on it when at normal operating temperature. The liners are also honed hot so that they are the correct dimensions when the engine is at operating temperature. Consequently, when cold the bores are not round and not the right size, which can upset people The Evo 4 takes things a step further: they build up weld bead in the triangular region between the bores to the edge and up to the head, then machine it back to a neat finish. The main reason for this is that they found that in the Evo 2 race engines they were loosing head gaskets with some alacrity so they wanted to stiffen up the top of the block as much as they could. It seems to have been successful so far. There seems to be quite a lot of work involved. Alan took a look at my liners as well - he thought that they were all acceptable except no.4, the bore of which was slightly bigger than he would like. The thing that caught his eye however was that the honing marks were deeper than he is used to seeing and at a much steeper angle - in his opinion they looked like perfect oil channels when using Accralites Honda Passion Orange, 640kg , and proud of it Edited by - c21vhpd on 27 Jun 2003 13:14:13 Link to comment Share on other sites More sharing options...
V7 SLR Posted June 27, 2003 Share Posted June 27, 2003 This is bloody fascinating. I love the idea of the interference fit liners. What are the prices of the Evo2 and 4 conversions? I appear to have the ultimate head-job now (thanks again Dave) so it seems prudent to look at block stiffening and (urgh... the cost) steel cranks. Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours Link to comment Share on other sites More sharing options...
c21vhpd Posted June 27, 2003 Author Share Posted June 27, 2003 Nig - didn't want to put prices in case some GOG thought it was advertising and chased me back to the bikesheds - The Evo2 conversion is £285 and the Evo4 is £685. For my purposes (fannying around in the Caterham Nippy Truck) I can't justify the Evo4 conversion - if I was a racer though I'm sure it would be a different story. Honda Passion Orange, 640kg , and proud of it Link to comment Share on other sites More sharing options...
V7 SLR Posted June 28, 2003 Share Posted June 28, 2003 Like you, I doubt I could justify the Evo4 conversion but as I'm going to have a look at the bottom end this Winter, I might just go for the Evo2 jobbie. I'll have to add up all the requirements and see what I can get past the finance manager. Thanks C21. Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours Link to comment Share on other sites More sharing options...
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