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4 minute(s) of a 64 minute read
4-18-2013
Here is some info from Total seal rings regarding their gapless style. It is one example of their requirements on ring gap.
Something to think about.
Top ring Bore x 0.0045"
Second Bore x 0.0035"
http://www.totalseal.com/TechPage.aspx#trRingInstall.
Over the years ring gaps have increased in spec for rebuild engine parts and I suspect the reason for that is ring maker reputation. Here's why. A lot of engines get overheated after the install. Thermostat stuck, radiator not cleand, broken old heater hose, loose hose clamp. Then if the rings expand enough they can butt together and break. Immediately it's someones fault. Usually the guy who rebuilt or the "crap" ring syndrome. Seen it many times, unfortunately! In standard applications Mahle use at least 0.005" sometimes 0.006.
Just stuff rattling around in the head I wanted to share with like minded fellows.
4-19-2013
Can you believe I've typed an extensive reply twice and have just bloody moved pages and lost me words! And now the missuss wants to talk!!!!!!!!!
Jim Miller reminds we practical men about our high school Geometry. Some Cam Grinders, most Cam Makers agree with him.
http://www.mid-lift.com/MID-LIFT-TECH.htm
Where"s that vino?
That head looks damn fine! Independent of all we've potificated about, we need to check the famous "Squish" shapes and clearances first. Then you'll have a very clear vision of the future. It might be as easy as getting the engine mocked up and measuring deck height to crown. Measure the head gasket fire ring diameter on a used gasket and measure it's crushed thickness.
1/ Piston crown height at TDC relative to deck .
2/Used gasket thickness and bore dimension.
a/ or the biggest diameter quality gasket data available to us.
3/ Head your going to use cc's.
4/ Both valve head diameters from that head
a/ If the valves are different to standard, can I have those diameters too, please? I suspect that Dani increased exhaust valve size, from the images. ( Very rudimentary theory is to have an exhaust opening area 7/8 of inlet area.Valve diameter or lift can change to suit 7/8 area In.)
5/ This might lead us to a sweet compromise with a move like bore/pistons in oversize to suit gasket dimension. Deck the block , for a squish depth of the head gasket, which are usually 0.037" to 0.040" . ( Splendid number for this) Or offset grind, which is simple. The hard part is to match bearings and rods again. Maybe Tamo's data can help here? Over size bore is sooo much easier if it fits in with gasket dimension.. Stroking is the ideal way, in todays technology but not easy. An identical rod with smaller big end is the starting place.
6/ Then we can calculate a static CR figure. Then valve timing for our DCR. Sure we may need to increase the piston bowl, but from the few numbers we have so far, probably not.
7/ Cylinder Mean Effective Pressure is more dependent on CR rather than boost. This is where we get the wind from to spin the turbo early. VNT and you boooggie!
8/ I love this s###!
The Dani spec cam on a std engine would have to have been a high rev very laggy cam, even if it had the correct springs and geometry.. 6.42 DCR .at 9 :1! 6:1 at 8.5. Hopeless....It needed 12 :1 to get close to what we want..
Once we sort the static CR we sort cam timing and especially lift. Springs are no problem as my colleague here down under makes them and retainers for me for what I want. If you want to read up with Jim Miller he'll explain why we can dial in quite low seat pressures relative to popular practice.
Burton Engineering establish 25% of Inlet valve head is the max lift needed. Not much more usefull wind will blow past, no matter how far it opens further. That said, opening aforememntioned inlet valve further than 25% does get it further open, earlier!!!!!!!!!!!!!!!!!!
I'm off to run naked now. It seems to be a common folly for lunatics and I don't want to miss out!