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Discussion Starter · #1 ·
Do you think it would be worth it to buy these for my sr20de block since I'm doing a head swap? They seem like they're direct bolt in without machining, but I'm not sure exactly, so I wanted to make sure these would work in the DE block without any other modification. I'm also gonna be using a b13 ECU for now until I can afford a JWT, but I figured while I had the block ready and prepared, would it be worth it to buy these and do that while I have everything apart? http://www.mossyperformance.com/product/?id=4583
They also have 10:1 pistons as well. Since the stock block is 9.5:1 with the stock DE head and should be a little higher with the VE head, it might put my compression at closer to 12:1 which I'm not sure I can use all the stock ECU and stuff to make it run. Any opinions??
 

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Professor Dingbat
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If you're putting a VE head on the DE block, I would suggest either 10:1 pistons, or roller rocker pistons. Those 20V pistons with the VE head might be a bit much for the street, although they do appear to be coated........
 

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Discussion Starter · #3 ·
would it be worth changing the pistons if I only did 10:1 since the DE motor is already 9.5:1...if I'm gonna spend the money, I wanna make sure it's worth doing and I also wanna make sure these will bolt into the DE block with no modification....anyone know??
 

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Discussion Starter · #5 ·
so will the 11.6:1 piston work? they have cuts in them.....but I'm not sure how all that stuff works to tell you the truth.....seems to me like I would need an upgraded ECU anyway to make it work. But I would love to be running 11.6:1 compression on a VE motor with sr16 cams for now until JWT comes out with new cams...
 

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15642uner
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well from what i read on here, the ve head raises the compression about 1 full point. so with you stock pistons, you're looking at 10.5:1 comp., RR 9.8:1 = 10.8:1 (however i always was under the impression RR motors got the .3 points from the smaller combustion chamber design), 10:1's = 11:1 comp., 11.6:1 (if thats what a 20v eguals in a de) = 12.6:1

so if thats to high for you, i guess you could always use a thicker headgasket for the de since you're using a de bottem end. and iirc, the de headgasktet also blocks the oil passage on the ve head which needs plugged.


also, what bongerhead said seems be a problem with de/ve hybrids. valve reliefs are very import factor when going with bigger cams in de/ve.
 

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Discussion Starter · #7 ·
so what would be the optimal pistons to pop in there? I figured I might as well do it while I have the motor apart....now would be the time to swap pistons and all that....I also don't wanna have to get the block honed out and machined to make the puistons work....I just wanna bolt the new ones in. So what's the overall opinion here?
 

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15642uner
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well before putting in any new pistons and rings, i would highly suggest getting the cylinder walls honed and new bearings installed. i would look into the 10.5:1 pistons (cant remember what manufacturer makes them) and seeing if the valve reliefs would be big enough or could have them cut deeper.



edit - unless of course the 11.6:1 20v piston actually nets that compression in a ve and not a de. the write up on mossy's page is a little misleading with saying it will net around 12:1 in a ve. this is why i assumed it was 11.6:1 in a de.
 

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15642uner
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yes, 12:1 is the highest i would run on 93 or 94 octane. also i dont think a standalone is absolutely necessary with that compression. some kind of extra management is, but not full standalone.
 

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Discussion Starter · #11 ·
well I do have an SAFC2, so that should work for fine tuning I would imagine......the way the website makes it sound is is 12:1 on VE and 11.6:1 on DE....I agree with you. I'll give Greg a call and find out tomorrow maybe just to make sure. It also sounds like these drop right in.
 

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15642uner
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yes they should drop right in since they are from a sr block with the 86mm bore, but i would still hone the walls to clean them up.
 

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15642uner
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boring is expensive, honing isnt. its done with a tool that you could use on drill or something.
 

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Discussion Starter · #15 ·
oh really? my bad...lol. So it's something I could do myself then?....I might do that then, but I need to find out more about these pistons....12:1 compression with sr16 cams sounds like it would def net over 200whp with a fuji header and 3" exhaust
 

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15642uner
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are you gonna be doing the ve head swap on a b15 se? if so, im curious, are you swapping over to the b13 harness? are you doin the spicing/cutting? or who?
 
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