Re: Grooves in cylinder walls

Posted by DJ.Voyce on April 21, 1998 at 11:33:56

In Reply to: Re: Groves in cylander walls
posted by Giles Dillingham on April 21, 1998 at 07:58:16

G'Day Giles,
The 0.060" maximum oversize, (You'll notice I did state it was a personal fetish) is purely a rule ofthumb which you can safely apply to almost any internal combustion engine & as you quite rightly mention it's to preserve a reasonable thickness of material on the cylinder walls which will aid heat transfer. However for every rule there's always an exception & I've seen some engine blocks over-bored for racing by more than 0.25" without having to sleeve them. My block has been sleeved back to 0.030" from a very worn 0.040" including wrist pin tram lines in one cylinder, for three reasons, the first being I bought a brand new set of 0.030" pistons for a good price, secondly I like to think that thematerials which are used for manufacturing todays sleeves must have improved at least a little in the last 70 years, then lastly & probably most importantly I was able to barter a job I'd done for my mate's company for all the machine work on my engine.
If your engine runs fine you don't have a problem & the increase in the compression ratio (& cubes) would give you a little more performance, but it'd be really hard to measure through the seat of your pants & definately wouldn't amount to any whiplash inducing kind of acceleration.
Regardz
DJ.
OutOfAfrica A's

: Interesting comment about oversizes, DJ.Why do you consider more that 0.060" overbore to be suspect?Are the cylinder walls getting too thin?Mine is now 0.100" over (I wish that it wasn't!) but after several thousand miles the only thing that I notice is that it runs like a top! BTW, a 0.100" overbore on a 4" bore motor corresponds to a 5% increase in compression ratio, or 4.5: 1 up to 4.73:1.My guess is that this wouldn't be noticeable in terms of performance.

: Giles Dillingham




Previous PageE-Mail Comment to WebmasterPost New MessagePrint MessageClose Window

© 1996-2010, Ahooga.Com

Anti Spam