LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Piston Swap

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Old 12-06-2011 | 08:47 AM
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Default Piston Swap

I'm sure this is a given but I just wanted to have opinons. I have a balanced forged RA with -16 cc pistons. Seems like I just can't get the numbers to get good compression. Question is if I swap the pistons for flat tops will I have to get the whole assemble rebalanced?
Old 12-06-2011 | 09:28 AM
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Originally Posted by Mystery Bird
I'm sure this is a given but I just wanted to have opinons. I have a balanced forged RA with -16 cc pistons. Seems like I just can't get the numbers to get good compression. Question is if I swap the pistons for flat tops will I have to get the whole assemble rebalanced?
not necessarily if you can get pistons that are within a few grams of the ones in there then all you will have to have the machine shop do is match the weights for each piston......bob weight is bob weight just make sure it comes up to be the same.....
Old 12-06-2011 | 09:58 AM
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Do I have any other cost effective options to bring compression up? With those pistons and the TF large chamber heads right now it would be about 9.5:1.
Old 12-06-2011 | 10:06 AM
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go with the thinnest gasket you can get and mill the heads......ill look into that deal you offered .....
Old 12-06-2011 | 10:18 AM
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Thought about that, is there a gasket smaller than .026 other than cometic's? Or can I run those with no deck work?
Old 12-06-2011 | 10:21 AM
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Originally Posted by Mystery Bird
Thought about that, is there a gasket smaller than .026 other than cometic's? Or can I run those with no deck work?
you can run one of them steel shiim gaskets like that victor reinz gasket.......ive personally never run them but ive heard alot about them.......as for the cometic they seal great u just have to make sure your RA on the block and head is very smooth and very flat.....
Old 12-11-2011 | 07:38 PM
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If I switched out the -16 cc pistons to the -5 cc flat top version they weigh 16 grams more. I assume that's too much to just swap out one for one? If so what am I looking at for machine work?
Old 12-12-2011 | 07:44 AM
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Originally Posted by Mystery Bird
If I switched out the -16 cc pistons to the -5 cc flat top version they weigh 16 grams more. I assume that's too much to just swap out one for one? If so what am I looking at for machine work?
yea pulling 16g off a piston and still having a piston left is kinda hard lol......balancing usually runs around 275-325 at a good shop.......before you go doing that though whats in the motor for pistons now??? whats the weight on them?
Old 12-12-2011 | 08:13 AM
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Do you already have the flat tops? If not, you can shop around for different pistons that weigh closer to what you have. Many piston manufacturers also offer wrist pins in different weights. I just went the other way from JE flat tops to Mahle -16cc dish and the pistons assemblies weighed exactly the same.
Old 12-12-2011 | 08:18 AM
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yea thats what i was going to look at for him........the srp pro series pistons are a really light really strong cost effective piston.....im thinking one of those may be his answer......
Old 12-12-2011 | 09:57 AM
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I have forged SRP's now that weigh 451 grams. I was looking at the same SRP's in the flat top which are 467 grams. I do not have the new pistons yet. Just trying to decide if I should change out the pistons or run the Felpro 1094 shim gasket and mill the heads. I'm a little scared to do that though.
Old 12-12-2011 | 10:06 AM
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Originally Posted by Mystery Bird
I have forged SRP's now that weigh 451 grams. I was looking at the same SRP's in the flat top which are 467 grams. I do not have the new pistons yet. Just trying to decide if I should change out the pistons or run the Felpro 1094 shim gasket and mill the heads. I'm a little scared to do that though.
why you scared to do that?? long as u have sufficent PTV which im sure you prob do id do that........let me look into the milling.......
Old 12-12-2011 | 10:14 AM
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I think I'm afraid of using that gasket since it's for a standard SBC and no deck work has be done for a smoother finish. Also, if I do that and shave the heads say .020 I'm still only looking a 10.3ish compression, but it puts the quench down around .042.
Old 12-12-2011 | 10:33 AM
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Originally Posted by Mystery Bird
I think I'm afraid of using that gasket since it's for a standard SBC and no deck work has be done for a smoother finish. Also, if I do that and shave the heads say .020 I'm still only looking a 10.3ish compression, but it puts the quench down around .042.
yea i mean its not great for head flow but the quench thats good.......i wouldn't be afraid to get that quench down into the low .030's .........030 is usually the limit for a steel rod motor.....im running .028 with no issues but thats on a billet rod also....
Old 12-12-2011 | 04:09 PM
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After talking with LE today I'm going to replace the pistons so I can take full advantage of the TFS heads and a larger cam. First I need to pull one piston to get an acurate weight then call SRP to match me up with a flat top piston/pin combo of the same weight. Anyone want to buy some SRP -16 dish pistons?
Old 12-12-2011 | 07:23 PM
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lol I'm already stuck with them as well lmao. I had loyd just shave the heads since I have a cast freakin crank and went with a torqy cam. One of these damn days I will finally build what I wanted in the first place. Someone with a blower set will eat those up. good pistons.
Old 12-12-2011 | 08:24 PM
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Don't need a blower to use those pistons. 54cc heads and a little off the deck they're good for 11:1 compression. I use those all the time on street driven LT4's.
Old 12-13-2011 | 07:25 AM
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That is an option but I'm using Trickflow heads and they have a 62cc chamber to begin with.
Old 12-13-2011 | 09:37 AM
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So I pulled number one out last night and weighed it. Piston: 455 grams, Pin: 129 grams. Should I weigh all of them or just go by one? I noticed it looked like some of the piston was ground off, for balancing I assume?
Old 12-13-2011 | 10:24 AM
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Yea, Lloyd shaved my stock heads down to about 52.5CC bowls and stock deck with a felpro head gasket leaves me arround 10.75 to 1 static. I had Mr. Gasket 5716's that put me at around 11 to 1 and they let go on me so I swaped to the felpro and I don't notice a difference. There a standard small block bore so I wasn't saying he needs a blower just that those pistons work good as an all around platform because they can be used with small volume bowls N/A and large volume bowls on a blower. He was nervous about cutting the heads he has.
I guess if you have the larger volume T/F heads I would be too since those are really good heads for a boost engine down the road if thats what you want to do. Have you thought about just getting a set LE2 heads and selling the T/F's or putting them on a shelf for a latter build?


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