ibexman Posted January 31, 2006 Share Posted January 31, 2006 Can a rebuilt engine ever be as good as a new one ???? Quote Link to comment Share on other sites More sharing options...
western Posted January 31, 2006 Share Posted January 31, 2006 Yes, I believe they can, sometimes better if care is taken with machining & build preparation. Quote Link to comment Share on other sites More sharing options...
pugwash Posted January 31, 2006 Share Posted January 31, 2006 Can a rebuilt engine ever be as good as a new one ???? Is this a university type question: "Discuss in your own words, whether or not a rebuilt engine can ever be as good as a new one" Ok here goes, it is my belief that in many cases a rebuilt engine can far surpass a new one. These cases would normally be limited to engines of an older design, or manufacturer (so that's all the LR engines then). it is doubtful whether a honda Vtec could ever perform as well when rebuilt as when new, as these engines are built up to certain tolerances, and thesed tolerances are lost due to wear and tear. however in older engines, particularily from mid 70s to mid 80s it is my beleif that engines were deisgned and built to a price, not to tolerances. Consequently engines were usually badly designed, and almost invariably badly put together, whilst manufacturing practices could be called shooddy at best. Lets take the venerable rover V8 as an example. For most of the manufacturing life these engines were built under a cloud of labour strikes and a "winter of discontent". Engines were virtually thrown together with the bare minimum of casting checks. Whilst these engines enjoy a VERY forgiving design, they produce very little power and great inefficiency. Recently i had a 4.0 rebuilt for me. Taking a used block, we found the liners in 4 cylinders had slipped (with evidence that this had occured a long time ago), taht the heads had been bolted down whilst out of alignment (thus forcing the dowels into the block) and bearing shells had been installed the wrong way round on one of the main bearings! This block was then rebuilt to a "blueprint" standard and beyond- top hat liners were installed- a very easy and cheap job to do when the block is first assembled, so there will be no more cracking or porosity. The rotating assembly was balanced to half a gram not 50grams, and the pistong rings were correctly and proprely installed. The heads were "lightly" ported to remove all the carp from the castings (again a quick job with the right tools) and the chambers were cc'd to give a common CR across them all. I can guarantee that this engine is smoother, more powerful, and much more economical than the standard RV8 (it returns 19.2mpg at 78mph steady). But everyone knows the RV8 has it's faults, so is it an isolated example? I would say not for any engine built over 10 years ago, and many engines built more than 5 years ago. If you think of the mods that can be done to ford pinto's, crossflows and essex V6s many of them benefit from rebuilds and some cheap mods. Same again for SBC 350 and Ford Windsors and Clevelands. As intonated above, more modern engines often don't benefit from a rebuild, as modern production tolerances are so high, and most blocks are built in such vast numbers, that producing a good engine is not a lot more expensive than producing a carp one (as it is mostly tooling costs that are expensive!) Nevertheless all modern engines can produce more power than they do, and the replacement of certain parts (for example pistons in Audi V8 engines) can lead to increased reliablity and better power. So is the future of rebuilding engines dead? Whilst in the long term, the trure rebuild (apart from race-bred engines) looks to be dead, the sheer number of older engines, which can be worked on relatively cheaply (whilst producing an engine to a custom spec), means that the modding and rebuilding of engines is likely to go on for some time. The end Quote Link to comment Share on other sites More sharing options...
ibexman Posted January 31, 2006 Author Share Posted January 31, 2006 Is this a university type question:"Discuss in your own words, whether or not a rebuilt engine can ever be as good as a new one" Ok here goes, it is my belief that in many cases a rebuilt engine can far surpass a new one. These cases would normally be limited to engines of an older design, or manufacturer (so that's all the LR engines then). it is doubtful whether a honda Vtec could ever perform as well when rebuilt as when new, as these engines are built up to certain tolerances, and thesed tolerances are lost due to wear and tear. however in older engines, particularily from mid 70s to mid 80s it is my beleif that engines were deisgned and built to a price, not to tolerances. Consequently engines were usually badly designed, and almost invariably badly put together, whilst manufacturing practices could be called shooddy at best. Lets take the venerable rover V8 as an example. For most of the manufacturing life these engines were built under a cloud of labour strikes and a "winter of discontent". Engines were virtually thrown together with the bare minimum of casting checks. Whilst these engines enjoy a VERY forgiving design, they produce very little power and great inefficiency. Recently i had a 4.0 rebuilt for me. Taking a used block, we found the liners in 4 cylinders had slipped (with evidence that this had occured a long time ago), taht the heads had been bolted down whilst out of alignment (thus forcing the dowels into the block) and bearing shells had been installed the wrong way round on one of the main bearings! This block was then rebuilt to a "blueprint" standard and beyond- top hat liners were installed- a very easy and cheap job to do when the block is first assembled, so there will be no more cracking or porosity. The rotating assembly was balanced to half a gram not 50grams, and the pistong rings were correctly and proprely installed. The heads were "lightly" ported to remove all the carp from the castings (again a quick job with the right tools) and the chambers were cc'd to give a common CR across them all. I can guarantee that this engine is smoother, more powerful, and much more economical than the standard RV8 (it returns 19.2mpg at 78mph steady). But everyone knows the RV8 has it's faults, so is it an isolated example? I would say not for any engine built over 10 years ago, and many engines built more than 5 years ago. If you think of the mods that can be done to ford pinto's, crossflows and essex V6s many of them benefit from rebuilds and some cheap mods. Same again for SBC 350 and Ford Windsors and Clevelands. As intonated above, more modern engines often don't benefit from a rebuild, as modern production tolerances are so high, and most blocks are built in such vast numbers, that producing a good engine is not a lot more expensive than producing a carp one (as it is mostly tooling costs that are expensive!) Nevertheless all modern engines can produce more power than they do, and the replacement of certain parts (for example pistons in Audi V8 engines) can lead to increased reliablity and better power. So is the future of rebuilding engines dead? Whilst in the long term, the trure rebuild (apart from race-bred engines) looks to be dead, the sheer number of older engines, which can be worked on relatively cheaply (whilst producing an engine to a custom spec), means that the modding and rebuilding of engines is likely to go on for some time. The end Quote Link to comment Share on other sites More sharing options...
TJ101 Posted January 31, 2006 Share Posted January 31, 2006 I will also agree, if built with care and attention, all the rally engine's i have had built/rebuilt ( ford crossflow.sunbeams,BDA's & cosworth etc,) have been as good, if not better then new !! Surley its down to a human eye, doing the job with time, rather that a robot !! Quote Link to comment Share on other sites More sharing options...
jjojjas Posted January 31, 2006 Share Posted January 31, 2006 Can a rebuilt engine ever be as good as a new one ???? yes without a doubt if you know an engine builder with a passion and knowledge in his work. I used to work for a guy who built A series race motors (mini) for competition use who was a bit of a legend on the race scene for his motors in BHP terms. As for Jap engines being all 100% spot on when they leave the factory my brother in law would argue that a lot of second rate work leaves engine production lines as they routinely have to re-set the "robot" as the tollerances get way out. (big rising sun car production plant in uk.....) I guess were still working to cost in many ways! Me, well I can build an engine to work, but thats it. I only know where the bits go! Jas Quote Link to comment Share on other sites More sharing options...
02GF74 Posted February 1, 2006 Share Posted February 1, 2006 Can a rebuilt engine ever be as good as a new one ???? yes. next question please? Quote Link to comment Share on other sites More sharing options...
mmgemini Posted February 1, 2006 Share Posted February 1, 2006 Two things. Ah the Rover V8. Denny Hulme's F1 World Championship winning engine in 1967. Remember also that the Ford Cosworth V8 that James Hunt won his World Championship with was reputed to have had the block stitched several times?? Certaily my 1300 Avenger engine rebuilt carefully with everything balanced was a better engine than a standard one. These new type engine I have no knoweledge of at all. I eat rat poison mike I can cause trouble in an empty house ! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.