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| gains with compression https://slantsix.org/forum/viewtopic.php?t=42748 |
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| Author: | Brussell [ Wed Dec 01, 2010 9:48 am ] |
| Post subject: | gains with compression |
Hi, so I'm getting the head shaved to 10:1 compression a little high some might say but I think it'll go ok, I'll be getting a better cam (currently stock) a little later on. Atm 350 holley, msd coil, big ignition, extractors, port and polish job and big air intake on my car, short ram runners ( might go the long ones soon). Question is what gains can i expect from from the compression upgrade? In a percentage torque or HP for a similar build to mind, or for a build that's just stock. both would be great. I just couldn't find alot of info. I'll also be getting bigger valves at the same time. Is it possible for me to hit the 200HP or 250 even? |
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| Author: | Joshie225 [ Wed Dec 01, 2010 10:14 am ] |
| Post subject: | |
http://www.popularhotrodding.com/tech/0 ... index.html You'll have a bad time with pinging if you try to run 10:1 with a stock cam. I suggest you save your money a while longer and change the cam when the head is off. Also, it's a little tough to get 10:1 on a 225 with stock pistons by simply milling the head. |
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| Author: | TurboNick [ Wed Dec 01, 2010 11:26 am ] |
| Post subject: | |
I say you should get some custom rods and pistons. A cam like Mr Skinner said and lots of money if you wanna hit 250 hp |
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| Author: | sandy in BC [ Wed Dec 01, 2010 1:00 pm ] |
| Post subject: | |
You can get 10:1 with stock pistons and rods. If you are installing larger valves you should reshape the combustion chamber or the valves will be shrouded. This lowers compression. If you just mill .160 thou off the head you will end up with your valves close to the deck at max lift.... and you may have to consider bore notching. If you mill from the block deck you will have more valve clearance and a better shaped chamber. You can even split the milling between the two. 10:1 with a stock cam will be stupid. You will ping it to death. Learn more about dynamic comression ratio. |
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| Author: | Brussell [ Wed Dec 01, 2010 6:26 pm ] |
| Post subject: | |
Thanks very much, the article mentioned above was helpful. After reading that. I'll go one of these ways. Wiesco pistons and rods gets approx 10.1 comp, will get a new cam as well (have one in mind) + I'll get the valves done. Or. I'll get the valves down, have the comp ratio bumped to 9 or 9.5:1 as high as I can without causing issues or possible detonation. And maybe I'll do some work to cool the engine down a bit more, 3 core radiator and fan. Hoping that I'll hit the 225 HP mark soon. |
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| Author: | hantayo13 [ Thu Dec 02, 2010 5:17 am ] |
| Post subject: | |
which cam you choose will also affect the compression ratio |
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| Author: | Evilsizer [ Sat Dec 11, 2010 10:56 pm ] |
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not sure if this setup might be the way you want to go http://www.moparmusclemagazine.com/proj ... index.html it is 1hp/cu in. i wonder if they have a dyno sheet for that engine... |
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| Author: | Brussell [ Sun Dec 12, 2010 4:28 am ] |
| Post subject: | |
Ahh yes exactly what I'm after. Only difference is, I'll bump up the compression just a smidgen more. and won't overbore unless I have to. And probably not a 500cfm 4bbl carb. And maybe a similar cam. Sounds decent to me I think I'll hit my 200 - 225 area pretty good. |
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