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Max Dry Sleeve Bore 2.5 Block/Left or Right SBC Pistons?

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Old 01-09-2018, 04:49 PM
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NCLA951
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Default Max Dry Sleeve Bore 2.5 Block/Left or Right SBC Pistons?

How big can you safely go in the 2.5 block with dry sleeves? Going to build either 2.85 or 3L, following the hybrid stoker plan. Just getting things together at this stage.

Also, when ordering pistons, do we want left or right bank SBC pistons? Assuming JE will sell half a V8 set.

Thanks and sorry if this has been covered elsewhere, couldn’t find it in search.
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Old 01-09-2018, 05:30 PM
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gruhsy
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For the piston size 4030 when I asked Sid about it. Should be able to go 4.04 but as you can see he recommended 4030.

See Sid's comments on my thread post number 17

https://rennlist.com/forums/944-turb...old-car-2.html

The pics at the end of the thread are a set of 8 pistons on my neighbors car. Michael Mount dry sleeve.
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Old 01-09-2018, 06:09 PM
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There’s a JE piston that works for all the other dimensions that’s 4.165”/105.791mm, (338234), I just don’t know if you can go that big bore wise in sleeved 2.5 block. Would be 105.918mm bore with .005” piston to wall clearance. Of course I might need a whole lot of intake and Head upgrades to handle the extra displacement. Otherwise will stick with original 2.85 route.

Are left or right SBC pistons good for our engines?
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Old 01-09-2018, 07:28 PM
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Most MFRs don't make a left vs right sided piston.
That's why they often have two sets of valve reliefs - depending which side the piston ends up on. Likely there is a "forward" direction with piston pin offset though.

Where do you intend to get the sleeving/crank work done, locally?
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Old 01-09-2018, 10:46 PM
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I’ve talked to a machine shop in my neighborhood, but open to local suggestions for solid machine work and experience with 944s.

Of course now that I settled on 2.85 HS Larts pushing a 3L block...
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Old 01-09-2018, 11:58 PM
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Performance Developments is local to you is it not?

Also not sure if you read on my thread.....the blown motor at the beginning are 106mm pistons in a 2.5L block. The sleeves in that block were undamaged when the engine blew up. I was impressed how good the sleeves still look.
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Old 01-10-2018, 12:50 AM
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you should've been looking this up 2 years ago...i sold a freshly honed, MM-sleeved 3.0 block with matching nearly brand-new pistons/rings (5 hours run time) for $1200...

Engine Supply in Santa Ana quoted me $1200 to sleeve the 944 block. They are a top-notch machine shop.

Perf. Developments could do it too but I doubt they'd touch it for that price.
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Old 01-10-2018, 12:45 PM
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Do they do crank offset work too?

And yes, there are lots of things I wish I had started or had the money to start in the past... like buying 911s before the bubble...
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Old 01-10-2018, 12:51 PM
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I got referred to "Marine Crankshaft" also in Santa Ana, they quoted $600 bucks to offset grind a 2.5 crank to 85+ mm @ Mitsubishi 45mm size and nitride it afterwards. $400 without nitriding. 3 week turnaround.

This pricing was last March though so it might have gone up a bit.
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Old 01-10-2018, 01:54 PM
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Originally Posted by V2Rocket View Post
I got referred to "Marine Crankshaft" also in Santa Ana, they quoted $600 bucks to offset grind a 2.5 crank to 85+ mm @ Mitsubishi 45mm size and nitride it afterwards. $400 without nitriding. 3 week turnaround.

This pricing was last March though so it might have gone up a bit.
thats the company that the legendary Greg Brown from Precision Motor Werks uses for their crank work, they are top
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Old 01-12-2018, 12:15 AM
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Originally Posted by V2Rocket View Post
you should've been looking this up 2 years ago...i sold a freshly honed, MM-sleeved 3.0 block with matching nearly brand-new pistons/rings (5 hours run time) for $1200...

Engine Supply in Santa Ana quoted me $1200 to sleeve the 944 block. They are a top-notch machine shop.

Perf. Developments could do it too but I doubt they'd touch it for that price.
Engine Supply did all the machine work on my Ausil 3L. Turned out great, all in including bore ,hone and head with new guides was ~$650. What work did you have done there? BTW Castillo Crankshaft in La Mirada did the crank knife and straightening. Balance Shop in Santa Ana did all the parts including the clutch pack and flywheel lightening. .
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Old 01-12-2018, 12:33 AM
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I've not yet had anything done there but I've talked a lot with Mike the owner and have full confidence in their abilities.
If they're good enough for Greg Brown (who calls Mike, the best machinist he's ever known), they're good enough for us schmucks, lol
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