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  #61  
Old 07-20-2010, 09:07 PM
Cam Cam is offline
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Re: 11:1 Engine Rebuild

Quote:
Originally Posted by TomsSVX View Post
Best to alter the head rather than the piston IMHO. I personally would make the measurements and add a safe amount of expansion clearance and order a custom gasket from Cometic.

Tom
Thats how I feel as well.

Picture time!
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'92 Ls-L Dark Teal
11:1 CR ECUTUNE pistons
ECUTUNE .256 duration intake/exhaust cams
ECUTUNE STAGE 2AV1 ECU
Z32 MAF/SR20DET injectors
Balanced & Blueprinted
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  #62  
Old 07-20-2010, 09:09 PM
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Re: 11:1 Engine Rebuild

I know, I know...before anyone else says it.

I need to clean my garage

I think I will do that tomorrow before I begin reassembly
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File Type: jpg IMG_1982.JPG (915.1 KB, 250 views)
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Cam

'92 Ls-L Dark Teal
11:1 CR ECUTUNE pistons
ECUTUNE .256 duration intake/exhaust cams
ECUTUNE STAGE 2AV1 ECU
Z32 MAF/SR20DET injectors
Balanced & Blueprinted
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  #63  
Old 07-20-2010, 11:29 PM
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Boxersix Boxersix is offline
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Re: 11:1 Engine Rebuild

Quote:
Originally Posted by TomsSVX View Post
Best to alter the head rather than the piston IMHO. I personally would make the measurements and add a safe amount of expansion clearance and order a custom gasket from Cometic.

Tom
I'm interested to know why you feel this way(Just on a personal note really) Every engine builder has their preferences Be warned, I may have a rebuttal or two
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  #64  
Old 07-21-2010, 12:02 AM
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Re: 11:1 Engine Rebuild

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Originally Posted by Boxersix View Post
I'm interested to know why you feel this way(Just on a personal note really) Every engine builder has their preferences Be warned, I may have a rebuttal or two
I take it your asking Tom, but my reasoning is it is cheaper, and simply reverses the problem at hand. Unless thicker gaskets are not good for some reason...

Out of curiousity, would you re-machine the pistons instead?
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'92 Ls-L Dark Teal
11:1 CR ECUTUNE pistons
ECUTUNE .256 duration intake/exhaust cams
ECUTUNE STAGE 2AV1 ECU
Z32 MAF/SR20DET injectors
Balanced & Blueprinted
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  #65  
Old 07-21-2010, 01:25 AM
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Re: 11:1 Engine Rebuild

Quote:
Originally Posted by Cam View Post
I take it your asking Tom, but my reasoning is it is cheaper, and simply reverses the problem at hand. Unless thicker gaskets are not good for some reason...

Out of curiousity, would you re-machine the pistons instead?
If it cannot be corrected by a few thousandths adjustment via the head gasket, then yes cutting the slugs is my method. Stacking HG thickness is fine but you have to control the TOTAL on a boxer motor. Simply stacking HG thickness to get piston clearance solves one issue but can create a whole other can of worms. Doing so forces the heads farther out from the directed OE centerline and throws the cam timing off. One can check this with a set of dial indicators and degree wheels on a motor and see the difference between a new set of heads and .015" decked heads I've lost track of how many flat motors I've built between Porsche, Ferrari, and Subaru, but I've run into the issue with about 1/3rd of those motors. Old aircooled P-car motors you actually shim the cylinders with different thickness gaskets, and Porsche was kind enough to give the motors infinitely adjustable cam timing in the sprockets to correct for the varying dimensionality(or aggressive cams for that matter)

Most recent was a 2.6L Cosworth build for a customers LGT. New OE EJ257 case(prebuilt SB via Cosworth), decked heads(not by me). Once the belt took tension, left bank was off near 2 degrees, right bank a hair more and was uncorrectable by any available HG....Unfortunately being a Cosworth SB I had little control and had to correct the issue with eccentric timing belt idlers(There's a reason why they exist now aftermarket ) Now a degree or two on a regular motor is livable, but on a high comp motor is can mean the loss of some notable power, and cam profile can further alter the outcome.

I in no way want to force my ideals down your throats here. This is just what I do for a living and just want to give you my thoughts based upon my experience When I build these type of motors for race purposes it's a process to say the least. But then the average porsche race motor build runs around 12-18 grand and it's 100% understandable that an Eg33 build may not have the financial backing to support every bit of work that should go into it, and that a sacrifice in one area to make up for a good chunk of money is a common route to take. It's not "wrong" or bad in any way.



One thing I forgot to add here.......In reality in a high dollar motor build all the machine work is spec'ed out and done PRIOR to buying parts(pistons, rings, bearings, etc) The pistons are then machined to fit the motor, so in the true big dollar builds it's never an issue as all dimensionality is factored in and the slug is tailored to suit that exact motor from the start. One a motor such as you EG33, this is usually never the case as you're using off the shelf components.

Side detour here since were on the subject of opinions: If the CH of the piston puts the domes above the deck height of the case enough to make contact with the combustion chamber, modifying the heads would require changes to the quench(and pending the motor and pistons involved) valve seat area, etc, etc. Without the benefit of 5 axis CNC it's substantially more difficult to machine combustion chambers 100% mirror to each other than it is for the pistons, and in a motor of this nature you want the heads perfectly CC'ed to each other. Setting up the pistons in a mill(or lathe in some cases) and removing the required material evenly if far easier and cheaper. In some case one has no choice but to modify the chambers, but this is done in accordance with pistons modifications, and then followed by a proper CC of the heads to balance them. CC'ing heads on a high comp motor is essential.


Can't say I know anyone that would modify the combustion chambers on a set of CC''ed or CNC'ed high comp heads over the pistons to achieve the goal here, unless the heads were not up to spec to begin with.


Here's a panoramic view of the main machine floor(so you don't think I'm blowing smoke up your azz )



Our cleaning room to the left(shot blasters, glass and soda machines, chemical baths, autoclave and preheat ovens, teardown rooms), Office and parts/supplies area beyond the wall to the right(actually centerd in the picture), engine dyno facility through the blue overhead. Crank machines, rod conditioners, line hones, etc to the right of the picture upstairs is the ~6,000 sq foot of core storage(heads, cranks, cams, etc), CNC, etc.(facility totals about 16,000 square feet, use to be an old mattress factory in the early 1900's-1950's) Anyone local is more than welcome to stop by for a little tour if you're in the area.



Hey, at least were all in this for the fun similar reason right


I think I've jabbered here enough for one post tonight, lol

Last edited by Boxersix; 07-21-2010 at 01:29 AM.
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  #66  
Old 07-21-2010, 02:05 AM
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Re: 11:1 Engine Rebuild

Nice job on the paint, Cam. You really took the masking seriously and it shows. How exactly did you go about painting it?

I'm learning a lot from this thread btw guys
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  #67  
Old 07-21-2010, 04:44 AM
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Re: 11:1 Engine Rebuild

Because in this case with these pistons, it is not just taking the dome of the piston down, it is the arch of the dome and the sides of the dome that will contact the head. With as much removal of deck surfaces as he has he may have top of the dome clearance issues as well though so... it could go either way

Tom
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  #68  
Old 07-21-2010, 07:09 AM
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Re: 11:1 Engine Rebuild

Thanks for the input guys.

I cleaned the block with soap and water, then blew it dry with an air nozzle on a compressor. They I masked the areas that I didn't want to get paint in them (oil pump, water pump, engine internals, decks, and bell housing). Then I layed plastic down, arranged the parts on it, and sprayed using dupli-color engine enamel. 2 light coats 10 minutes apart, with a final "wet" coat (moderately thick coat).

With all the ketones inside the paint, it was almost impossible to get runs. Good stuff as far as application goes, it was very simple. To touch it up I sprayed the can into a mixing cup (FACING AWAY FROM ME) and used a brush to get all the little spots I could not spray. I then finished by wiping all the areas that were not supposed to be painted again with MEK (Mehtyl Ethyl Ketone).

All of this was done OUTSIDE where it was well ventilated. And let me tell you, the fumes of that ketone still were getting to me. Nasty stuff. One should always wear thick nitrile gloves when using ketones, and NEVER do so inside without a respirator or industrial ventilation system. Same goes for spraying the paint, although thick gloves are not necessary. I still recommend some form of protective glove.

As far as the pistons go, .006" was removed from the decks on the block. The heads were barely touched, and have plenty of meat left on them. I can get the measurements up here if necessary. Since it is such a minute amount in reality, I am not seeing such a small increase in HG thickness causing other issues. The pistons were made extremely well and specifically for this engine. If I can restore the stock (+- .002" cut to the decks on the head) height of the decks it should guarantee that I will have no issues. Theoretically. As I have said though, we shall see when I assemble the short block.
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Cam

'92 Ls-L Dark Teal
11:1 CR ECUTUNE pistons
ECUTUNE .256 duration intake/exhaust cams
ECUTUNE STAGE 2AV1 ECU
Z32 MAF/SR20DET injectors
Balanced & Blueprinted

Last edited by Cam; 04-03-2011 at 09:30 PM.
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  #69  
Old 07-21-2010, 11:07 PM
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Re: 11:1 Engine Rebuild

Here is a picture of the crank case with crank shaft, rods, and bearings installed. Before installation they were meticulously cleaned along with mating surfaces, then assembled with moly graphite assembly lube per LAN's engine build how-to. In the picture there is some silicone missing around the oil pump area and around the bolt holes. This was corrected before assembly. All bolts were torqued per the FSM.
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File Type: jpg IMG_1984.JPG (810.8 KB, 250 views)
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Cam

'92 Ls-L Dark Teal
11:1 CR ECUTUNE pistons
ECUTUNE .256 duration intake/exhaust cams
ECUTUNE STAGE 2AV1 ECU
Z32 MAF/SR20DET injectors
Balanced & Blueprinted

Last edited by Cam; 07-21-2010 at 11:18 PM.
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  #70  
Old 07-21-2010, 11:10 PM
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Re: 11:1 Engine Rebuild

And here is the assembled crankcase with the exception of the pistons. I have yet to set the rings, but once I do they will be installed. Then it's time to figure out if I need those special gaskets.
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File Type: jpg IMG_1988.JPG (867.4 KB, 256 views)
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Cam

'92 Ls-L Dark Teal
11:1 CR ECUTUNE pistons
ECUTUNE .256 duration intake/exhaust cams
ECUTUNE STAGE 2AV1 ECU
Z32 MAF/SR20DET injectors
Balanced & Blueprinted
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  #71  
Old 07-21-2010, 11:31 PM
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Re: 11:1 Engine Rebuild

Nice work Cam...
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  #72  
Old 07-21-2010, 11:34 PM
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Re: 11:1 Engine Rebuild

Thanks

By the way, Cometic sells gaskets at .070" or .075" thick for the same price as the stock thickness (.066") ones on their sites catalogue.
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'92 Ls-L Dark Teal
11:1 CR ECUTUNE pistons
ECUTUNE .256 duration intake/exhaust cams
ECUTUNE STAGE 2AV1 ECU
Z32 MAF/SR20DET injectors
Balanced & Blueprinted
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  #73  
Old 07-22-2010, 12:04 AM
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Re: 11:1 Engine Rebuild

Get in touch with Nick Arias from atomicspeedware.com
He usually provides the best pricings on Cometics.
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1994 Silver SVX in hybernation, awaiting for the monsterous awakening (Lebanon)
1967 Mercedes-Benz 250SL Euro Specs, Hard/Softtop, White/Red. Under Complete Restoration
2013 Mercedes-Benz SL350 Euro Specs, White/Red. Mint... Another step into SL Collection.
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  #74  
Old 07-23-2010, 10:46 PM
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Re: 11:1 Engine Rebuild

Got the pistons installed today. The 1,3,5 side required NO filing of the rings. Fit was perfect out the box. Same goes for one of the cylinders on the 2,4,6 side. Beginners luck, i suppose...

Once I reinstall the sump and pan, the bottom end will be all closed up. I still need to measure the protrusion of the pistons. It looks like it is going to be close, but then again, it always does when your talking about thousandths of an inch.
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Cam

'92 Ls-L Dark Teal
11:1 CR ECUTUNE pistons
ECUTUNE .256 duration intake/exhaust cams
ECUTUNE STAGE 2AV1 ECU
Z32 MAF/SR20DET injectors
Balanced & Blueprinted
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  #75  
Old 07-24-2010, 02:11 PM
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Re: 11:1 Engine Rebuild

Okay, so, here are the rough measurements I took today.

Piston protrusion past head gasket - 3/16"
depth of dish on head - 1/2 "
spark plug protrusion from head - 3/16"

1/2" - 3/16" - 3/16" = 1/8"

I don't think my piston will swell an 1/8" , but to get more relyable measurements I will use some clay on my domes and run the crank over to see how much space I have. Wish my luck (will probably get around to it tomorrow). I will also take some pics then. Gotta love pics
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'92 Ls-L Dark Teal
11:1 CR ECUTUNE pistons
ECUTUNE .256 duration intake/exhaust cams
ECUTUNE STAGE 2AV1 ECU
Z32 MAF/SR20DET injectors
Balanced & Blueprinted
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