Forum for competition engine enthusiasts. RIP Guy Croft 09/11/2020 - This forum will continue both as a source of information and as a memorial to Guy.
http://www.guy-croft.com/
Hi GuyGuy Croft wrote:Hi
there is something in the GC V/W workshop on this. If it doesn't help/apply come back to me here.
GC
Guy Croft wrote:OK
The run-in really depends on the honing technique.
The fastest I have ever run-in a competition engine was 20 mins round and round an industrial estate at relatively low speeds - 1,2,3 gear up to 4500 rpm and no more than 1/2-5/8 throttle. That car was a 16v Tipo featured in Cars and Car Coversions in the mid 90s by Gerard Sauer. We ran-in on Castrol GTX multigrade 10W40and then changed to the exceptional Fiat Lubricants 'Selenia Racing' 10W/60 fully synthetic and it ran for years and years without any ring/bore trouble at all.
I prepped those bores for chrome plated steel top rings with a 180 grit silicon-carbide Flex Hone, a world-beating honing tool that is superior, in my view - to anything else for that job, and finish-cleaned with very hit water & detergent, before drying and oiling.
If engine has been finish-honed with anything else the bedding in phase needs to be longer and there wil be a higher level of ring and bore wear during it. This BTW comes straight from Brush Research Manufacturing, the guys who make it. See:
http://www.brushresearch.com/Index.cfm/ ... eTools.htm
The trouble with a competition engine is you need to do an oil change after bedding in, unless you go easy in the 1st race event and use that as part of the process.
If you do that - you must use a race grade oil that works both for bed-in and the event, like Valvoline VR1, I'm not an oil expert but that's an oil I've used a lot for dyno test and I know it's plenty good enough.
Truth is these days that it is possible to phone (it's worth the trouble, I'd say) the manufacturers of race oils and ask them, Silkoline, Redline, Millers - there are quite a few in the UK. There are fantastic oils around, Texaco makes one that was particularly recommended to me. Look for the designation code on the tin.
You want API SH or J
and CCMG G5
You must not race at full-load/power in my view - on anything of lower upper temperature viscosity rating of 5 and 60 is better eg:
5W/50
10W60
I would never compete on any of the 'modern' 40 high temp viscosity oils, ever. If you do and it works, that's fine by me!
You can ignore the 5W bit as it refers to low temperature. You need to keep the oil temp down to 85-90 deg C otherwise - it's quite simple - the oil will be so thin that the leakdown rate in the bearings may exceed the pump delivery. Not so much of a problem with modern 'internal-external' crescent pumps with big rotors but definitely a problem with pre-90's engines with old-fashioned gear pumps.
Bearing in mind that a lot of the time, unless your engine is dry sumped or equipped with a very good baffled sump with windage tray, static baffles and trapdoors and/or oil pressure accumulator, the thing wil be pumping crankcase gas a lot of the time, so one thing you must NOT take a chance on is over-hot oil. If your system is not instrumented with oil temp, pressure and low pressure warning light - you need them.
Castol are always very helpful, their helpline in Dublin is 8852121
What is the minimum bedding-in for your motor? Well, let's assume is it hasn't been Flex-Honed. I say it needs 20 minutes of light-medium load (throttle) at speeds 2500 - 4500 then 20 minutes 3500-5500 light-medium followed by 10 minutes 3000-6000 medium-high load. Running it off load at idle will not achieve anything - you need to get the cylinder pressure on the rings or it will just glaze up and never give any power.
Don't use synthetic oil for bedding-in although semi-syn can work, I have successfully used Castrol and Esso semi-syn types that way. But only - in both cases - because the client bought the wrong stuff and I didn't have the heart to tell him...
If that doesn't work for you, either it's been honed very rough or the fuelling and ignition are wrong, or it'g got high back pressure in the exhaust.
As far as road cars go you will understand readily that a longer regime is safer and certainly not harmful, 500 miles of light then medium use is the norm, a bit like like article on bedding in that you read. I pretty well got out of road engines last year, I just could not rely on clients to do what they were told (by me) and do things right, wow - too stressful!
I hope this advice is helpful, might be worth asking the guys who prepped the block. Everyone has their own system, I am reading betwen the lines slightly here.
Sorry if you know much/most of what I have written, I write for all, just use your post as a 'vehicle' for it.
GC
GuyGuy Croft wrote:Hi, good, thanks.
Please not a very unfortunate 'typo' see bold my original edited above! Re viscosity ratings.
No proof reader here...!
GC
What would you suggest for my engine?Guy Croft wrote:Please list the engine type and spec and what it is going to be used for, thanks.
Eg: cams, CR, fuel system, ex system, car, head work.
Sorry if it is somewhere else on the site, copy and paste if need be.
GC
GuyGuy Croft wrote:Please list the engine type and spec and what it is going to be used for, thanks.
Eg: cams, CR, fuel system, ex system, car, head work.
Sorry if it is somewhere else on the site, copy and paste if need be.
GC