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| 300WHP Supernatural 3.XX Coming Soon! (Page 9/54) |
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mender
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MAR 17, 08:29 PM
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| quote | Originally posted by La fiera:
You lost me Will!!
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The trend now is toward thinner rings so that they seal better by conforming to the cylinder wall and have less friction. A win/win. My usual ring package of choice is 1.0/1.5/3.0. Had the stock GM rings on my last engine and the leakdown was 4% after the rebuild and also after 80+ hours of racing.[This message has been edited by mender (edited 03-17-2018).]
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mender
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MAR 17, 08:31 PM
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| quote | Originally posted by La fiera:
The problem was that these pistons come in set of 4 and I bought 2 separately. The package of 4 were within a gram or two but the other 2 are off by a lot, 11g like you mentioned. But I'm getting there little by little.
To answer your question I drill little holes at low depth under the crown. I do it a little at a time and what I do in one side I repeat at the opposite side.
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I figured they were from two batches. I buy V8 sets when I can and use the best six, much less work and usually quite cheap - if you can find the right sizes.
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Will
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MAR 17, 08:51 PM
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| quote | Originally posted by La fiera:
You lost me Will!!
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The heavier ring requires more force to turn around. It's more likely to flutter at high RPM unless it has a LOT of tension. If it has a lot of tension, then it has a lot of drag. If it has a lot of tension, then it has a large radial dimension and will be stiffer and more senstive to imperfections in the bore roundness and hone consistency.
Even the best bores in the world aren't perfect. They aren't in a GM 60 degree V6 either.
If you're putting championship effort into the hone, then you can run a 1.0-1.2 steel top ring (gapless even better!) with lateral gas ports, 2.0 or less Napier 2nd ring and pick up power. I would say a 2.7 or less oil ring, but you like to run your bearing clearances wide, so you'll probably need a stiff oil ring to scrape all that oil off the bore walls.
Getting to 300 at the wheels takes all the tricks.
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Will
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MAR 17, 08:53 PM
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| quote | Originally posted by mender:
The trend now is toward thinner rings so that they seal better by conforming to the cylinder wall and have less friction. A win/win. My usual ring package of choice is 1.0/1.5/3.0. Had the stock GM rings on my last engine and the leakdown was 4% after the rebuild and also after 80+ hours of racing.
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BAM!
Mender beat me to it.[This message has been edited by Will (edited 03-17-2018).]
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La fiera
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MAR 17, 09:31 PM
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Well with the higher comp ratio the thicker rings can take more abuse over a longer period of time. Also they flex less under higher compression ratio.
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La fiera
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MAR 17, 09:32 PM
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Double post! [This message has been edited by La fiera (edited 03-17-2018).]
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La fiera
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MAR 17, 09:36 PM
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| quote | Originally posted by mender:
The trend now is toward thinner rings so that they seal better by conforming to the cylinder wall and have less friction. A win/win. My usual ring package of choice is 1.0/1.5/3.0. Had the stock GM rings on my last engine and the leakdown was 4% after the rebuild and also after 80+ hours of racing.
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80hrs of what kind of racing? 1/4 mile racing?
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La fiera
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MAR 17, 09:41 PM
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| quote | Originally posted by Will:
Getting to 300 at the wheels takes all the tricks. |
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Let's see who's right at the end!
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mender
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MAR 18, 01:06 AM
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| quote | Originally posted by La fiera:
80hrs of what kind of racing? 1/4 mile racing?
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Endurance road course. Chumpcar (now Champcar) to be precise. The double row timing chain installed during the rebuild was starting to get loose and the valve guides and seals were also worn but the ring and valve seal were where they started.[This message has been edited by mender (edited 03-18-2018).]
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mender
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MAR 18, 01:16 AM
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| quote | Originally posted by La fiera:
Well with the higher comp ratio the thicker rings can take more abuse over a longer period of time. Also they flex less under higher compression ratio. |
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The piston lands support the rings so there is essentially no flexing to worry about if your pistons are accurately machined. Flexing less is a disadvantage when it comes to sealing the bore.
The rings in my 10.5:1 3500 were subjected to an air-fuel ratio of 13.8:1 and a few times the mixture went even leaner because of a bad MAF and a clogged fuel filter. No issues. I wouldn't hesitate to run 10-12 psi boost with the same rings.
Friction lost to extra drag because of the rings is like a tax you never see: it comes off the bottom line without you knowing it. When you have your short block assembled, slowly turn the engine over with a torque wrench and measure the amount or torque needed. I did a 540 that only required 24 ft.lbs to turn and it made 796 hp @ 6600 rpm.
Lower drag from the ring package is free horsepower.[This message has been edited by mender (edited 03-18-2018).]
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