Domed vs. Flat Top Pistons
10-26-2012, 05:34 PM
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Domed vs. Flat Top Pistons What's the difference between Dome and Flat Top pistons? (Lord help me if someone says one's flat and the other is domed...) haha! I am looking at building a motor..eventually.. and was looking at 383 Rotating assemblies, and the options are pretty abundant. Also, what is affected when changing "cc" size of the piston? Compression?
How would a newbie such as myself go about picking out a set of pistons and knowing what type/size is needed for my application? Someone school me please...
Thanks!
-Michael
How would a newbie such as myself go about picking out a set of pistons and knowing what type/size is needed for my application? Someone school me please...
Thanks!
-Michael
10-26-2012, 05:44 PM
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One is flat, and the other is domed.....but you knew that already.
Seriously though, it's a decision that has to be made in the context of the over-all build picture. You need to consider such things as desired static compression, desired quench, head gasket volume, and cylinder head combustion chamber volume. It depends on what your goals are....NA, or FI as well. What are your overall goals? What fuel do you plan on burning? Monster cam, or no?
Generally, less of a dish (or more of a dome) will increase static compression in a build....but it also depends on what heads/combustion chamber volume that will be used in the build.
Seriously though, it's a decision that has to be made in the context of the over-all build picture. You need to consider such things as desired static compression, desired quench, head gasket volume, and cylinder head combustion chamber volume. It depends on what your goals are....NA, or FI as well. What are your overall goals? What fuel do you plan on burning? Monster cam, or no?
Generally, less of a dish (or more of a dome) will increase static compression in a build....but it also depends on what heads/combustion chamber volume that will be used in the build.
10-26-2012, 05:59 PM
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One is flat, and the other is domed.....but you knew that already.
Seriously though, it's a decision that has to be made in the context of the over-all build picture. You need to consider such things as desired static compression, desired quench, head gasket volume, and cylinder head combustion chamber volume. It depends on what your goals are....NA, or FI as well. What are your overall goals? What fuel do you plan on burning? Monster cam, or no?
Generally, less of a dish (or more of a dome) will increase static compression in a build....but it also depends on what heads/combustion chamber volume that will be used in the build.
Seriously though, it's a decision that has to be made in the context of the over-all build picture. You need to consider such things as desired static compression, desired quench, head gasket volume, and cylinder head combustion chamber volume. It depends on what your goals are....NA, or FI as well. What are your overall goals? What fuel do you plan on burning? Monster cam, or no?
Generally, less of a dish (or more of a dome) will increase static compression in a build....but it also depends on what heads/combustion chamber volume that will be used in the build.
What do you mean the overall build picture? I want a high compression (but still using pump gas) reliable street car, with street manners. I do want a pretty big cam but this will be N/A so it won't be massive.
10-26-2012, 06:15 PM
#4
It all depends on your "build" or combination of parts. I have a 370 with "flat tops" BUT they have 1.7cc valve reliefs and with my heads, I am at 12:1 static compression. If I swapped to bigger chamber heads, it would lower my compression.
You also have to take into affect the cam of choice and different cams "bleed off" more than others.
Personally, in a street car, I would get flat tops with a 1.7-2.2 valve relief and pick your heads/cam to get the compression you want.
What is your idea of High Compression?
You also have to take into affect the cam of choice and different cams "bleed off" more than others.
Personally, in a street car, I would get flat tops with a 1.7-2.2 valve relief and pick your heads/cam to get the compression you want.
What is your idea of High Compression?
10-26-2012, 06:31 PM
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It all depends on your "build" or combination of parts. I have a 370 with "flat tops" BUT they have 1.7cc valve reliefs and with my heads, I am at 12:1 static compression. If I swapped to bigger chamber heads, it would lower my compression.
You also have to take into affect the cam of choice and different cams "bleed off" more than others.
Personally, in a street car, I would get flat tops with a 1.7-2.2 valve relief and pick your heads/cam to get the compression you want.
What is your idea of High Compression?
You also have to take into affect the cam of choice and different cams "bleed off" more than others.
Personally, in a street car, I would get flat tops with a 1.7-2.2 valve relief and pick your heads/cam to get the compression you want.
What is your idea of High Compression?
My idea of high compression would be the highest I could get and still use pump gas. I can't really see the need for race fuel or an octane booster after every fill up in a street car...
10-26-2012, 06:50 PM
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And I have no idea where to start on running E85? I think it would be cool and I see a lot of people running it in some of the build threads I read. What all needs to be done in order to efficiently run E85?
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10-26-2012, 07:07 PM
#8
E85 isn't efficient, neither is modding your car they way you are wanting to..lol
All jokes aside, I am running 12:1 comp and am good on 93 99% of the time.
I think you need to speak to a sponsor here that builds engines to give you a better idea on a direction to go. I cant stress enough that you need to educate yourself. There is no need in going into a build like this "blindly". You will be happier in the long run with parts that work well together vs going for MAX compression.
Why are you seeking Max compression? What is your goals? What is the purpose of the build, besides to have a street car? You have a "street car" now. Not knocking your ideas, just looking for a bit more insight.
10-26-2012, 07:11 PM
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E85 isn't efficient, neither is modding your car they way you are wanting to..lol
All jokes aside, I am running 12:1 comp and am good on 93 99% of the time.
I think you need to speak to a sponsor here that builds engines to give you a better idea on a direction to go. I cant stress enough that you need to educate yourself. There is no need in going into a build like this "blindly". You will be happier in the long run with parts that work well together vs going for MAX compression.
Why are you seeking Max compression? What is your goals? What is the purpose of the build, besides to have a street car? You have a "street car" now. Not knocking your ideas, just looking for a bit more insight.
All jokes aside, I am running 12:1 comp and am good on 93 99% of the time.
I think you need to speak to a sponsor here that builds engines to give you a better idea on a direction to go. I cant stress enough that you need to educate yourself. There is no need in going into a build like this "blindly". You will be happier in the long run with parts that work well together vs going for MAX compression.
Why are you seeking Max compression? What is your goals? What is the purpose of the build, besides to have a street car? You have a "street car" now. Not knocking your ideas, just looking for a bit more insight.
10-26-2012, 07:29 PM
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I am looking for 500 at the wheels with potential for boost later down the road. I'm looking into a 383 because LS1 blocks can be had for pretty cheap and I'm not in a real hurry get it running. I have also thought about a 402/408 but since the initial difference in blocks will be more for the 6.0 I wanted to try a 383. Also, I feel like with the right parts, a 383 could have just as much potential (minus a bit of power) than that of a 408.
P.S. I'm internet "window shopping" right now and I'm not exactly sure where to go.. TSP has rotating assemblies for roughly 2k but then another $300 to balance it? Why wouldn't I just go with the Callies rotating assembly and have it come already balanced and ready to go with (my opinion) are superior parts. Any thoughts on this?
Thanks!
10-26-2012, 07:36 PM
#13
Honestly in your situation, I would just shop for a longblock (block/rotating assembly/heads assembled) of your liking and be done with it. Bolt on all the intake/oil pan/accessories and be done.
If you piece it out and try to save money, you will spend more in the long run. Trust me, I have been there and done that.
I would go LS3 in my opinion.
If you piece it out and try to save money, you will spend more in the long run. Trust me, I have been there and done that.
I would go LS3 in my opinion.
10-26-2012, 09:57 PM
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Honestly in your situation, I would just shop for a longblock (block/rotating assembly/heads assembled) of your liking and be done with it. Bolt on all the intake/oil pan/accessories and be done.
If you piece it out and try to save money, you will spend more in the long run. Trust me, I have been there and done that.
I would go LS3 in my opinion.
If you piece it out and try to save money, you will spend more in the long run. Trust me, I have been there and done that.
I would go LS3 in my opinion.
P.S. Why would you go LS3? Any reasoning behind that? Just curious..
10-27-2012, 12:18 AM
#15
Building an engine for na, with the possibility of boost is a give and take. If you go with a flat top piston now on a 383, your going to be hard pressed to find a gasket and chamber size later on down the road to lower the compression for boost.
On the other hand, if you go with a dished piston now, your going to have to run some seriously milled/welded heads to give you the high compression you need now.
I would go with a flat top with a reverse dome, as opposed to a full dish. This will still give you quench pads to keep that up, and give you moderate compression now, and still allow you to drop the compression with the chamber size later on down the road for boost.
On the other hand, if you go with a dished piston now, your going to have to run some seriously milled/welded heads to give you the high compression you need now.
I would go with a flat top with a reverse dome, as opposed to a full dish. This will still give you quench pads to keep that up, and give you moderate compression now, and still allow you to drop the compression with the chamber size later on down the road for boost.
10-27-2012, 06:41 AM
#16
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1- You either build for boost or NA. The 2 are two different annimals. Boost on street does not like high compression. 10:1 is the highest I would go with only 10psi boost (meth injected).
2- In either case, I would run flat tops with 2>4cc reliefs. Like Wiseco with hellfire rings and boost reliefs.
2- In either case, I would run flat tops with 2>4cc reliefs. Like Wiseco with hellfire rings and boost reliefs.
10-27-2012, 11:27 AM
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1- You either build for boost or NA. The 2 are two different annimals. Boost on street does not like high compression. 10:1 is the highest I would go with only 10psi boost (meth injected).
2- In either case, I would run flat tops with 2>4cc reliefs. Like Wiseco with hellfire rings and boost reliefs.
2- In either case, I would run flat tops with 2>4cc reliefs. Like Wiseco with hellfire rings and boost reliefs.
If not, what about nitrous? Anything special I should do before building the motor so that I don't just have to tear it down again?
I'm not trying to half *** anything, I just would like to kill 2 birds with one stone yah know? It's difficult to find money (for me) to build a motor only to have to tear it down again and put something different, But hey, that's why we all love cars right? haha
Thanks for the info.!
10-27-2012, 11:30 AM
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I don't want to focus too much on boost right now, I just want to leave all my doors open for later down the road. I assume that building a 383 would have enough power for a daily driver.
That being said, what kind of numbers are most people putting down? I'm hoping for mid-500's? Is that crazy?
That being said, what kind of numbers are most people putting down? I'm hoping for mid-500's? Is that crazy?
10-27-2012, 03:17 PM
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I'm thinking that if I can achieve 550 rwhp or so, I won't need boost. So, with all the boost aside, what would you do? Buy flat tops and then dictate the compression with the heads?
Sorry for the confusion, As I'm not building this motor right this second I have a lot of options I would like to see happen but I just can't really make up my mind
Sorry for the confusion, As I'm not building this motor right this second I have a lot of options I would like to see happen but I just can't really make up my mind