HomemadeTurbo - DIY Turbo Forum

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- - got rings??? (https://www.homemadeturbo.com/forced-induction-7/got-rings-13042/)

ok... here's the prediciment,
i have a a6 that i'm rebuilding w/ stock internals (rods and slugs). i have a z6 head, and yes, i'm going to use it. soon to be going turbo (spring time). max 8 lbs of boost. going to go w/ zdyne eng mgt, unless i convert to obd1, then i'll go hondata.... don't want ghettodyne(i want "on the fly tuning")

i'm going to get the cyl's bored .020" over to clean them up.
i'm wondering if the "middle of the road" rings will be safe?
i can get "Beck-Arnley" rings.... "Autozone" for about $60, but if i can find better ones that would ease my mind of blowby, i'll spend the extra $$$.

i'm going to stay w/ the 10.2-5 c/r.

just wondering what u guys think or would go w/ for rings...

thanks,
mike

go with stock honda rings. best bet.!

Stock honda. Avoid autozone at all costs.

-David

Don't overbore unless you have to. And honda rings. ;)

total seal rings are bad ass they have hardly any blowby and are only around $150

ive heard bad things about total seal rings and boost (from larry at endyn so i wouldnt get them if he says they are ----)... i got je rings for like 100

Will that head contribute to a lower/higher compression on that block? I have one source that seems to think it'll result in 9.7 compression.
-PHiZ

WOW good thread. How much are the Honda rings? Damn $100 for je is expensive :( That's 1/3 the price of an entire long block.

you think thats bad....665 for crower rods

http://www.knology.net/~jediklc/D.htm

With your .002 (.5mm)overbore, a6 block and pistons, z6 head and stock a6 head gasket(.048) You should have around 9.8.1 compression. If you stay stock bore with the same setup you will have around 9.7.1

with stock 3 layer y8 gasket=10.05.1

with 2 layer y8 gasket=10.34.1

I have also heard bad bad things about total seal rings and forced induction.

-David

that makes no sense...how could an overbore raise the compression, it would lower it if anything

overbore=more displacment. You are compressing more air into the same size combustion chamber. Someone correct me if I am wrong.

-David

that doesnt make sense to me, it wont raise the compression since the compression height of the piston is the same

Quote:

Originally Posted by ghettoturbo

that doesnt make sense to me, it wont raise the compression since the compression height of the piston is the same

that would be true if the head were just a flat plate on top of the pistons (which btw would result in a CR of around 37:1). i'm sure you know the head isn't flat, but has arched areas (for the valves and spark plug) with a specfic volume that doesn't change with the bore of the cylinder.
when you increase the bore of the cylinder, you increase the displacement of the engine slightly. the extra air has to go somewhere during the compression stroke, and last i checked, overbore A6s don't develop a 500+ psi ring of air around the rim of the piston - it contributes to an increase in overall compression.

thanks for the backup. let me try to explain it like this. These are all just arbitrary numbers by the way. Its just the general idea. the area of a circle is pie x r^2 so.
stock bore 75mm. over bore of .5 mm. take the area of the overored cyl and subtract the area of the stock bore.

so the area of the top of the overbored cyl is 4476.97mm^2 and the stock bore is 4417.86mm^2

subtract and you get a ring of area 59.11mm^2.

Now for shits and giggles assume the z6 piston hase a .5 mm piston to deck height. It's actually zero but that doesn't matter. multiply the area of the ring by the .5mm to get the volume of the area that you have added to the compression chamber.
59.11mm^2 x .5mm =29.555mm^3

Now that ring of overbore goes all the way down the cyl. So take the area of that ring and multiply it by the stroke of 90mm.
so 59.11mm^ x 90mm = 5319.99mm^3

Now all these numbers arnt exactly right on but the concept is the same.
when you over bore you are compressing 5319.99mm^3 into a 59.11mm^3 space. Its not exactly like this but the concept holds true. The z6 actually has zero piston the deck hieght and the overbore of the headgasket is already included in the stock compression ratio. In real life you are just compressing ~5320mm^3 into the same exact area you were with a stock bore.

-David

minus the math i sat down last night and figured that out...good explanation, except that its not the same area as stock because of the overbore (doesnt affect much)

Yeah I didn't figue the total volume displaced. just the small ring. like sitting a stock bore piston into an overbored cyl and measuring the area around it. then measuring that volume all the way down the cyl. Not accurate numbers but I hope it explains the concept.

-David