NemeSS

iTrader: (127)

Correct,
But I think he is using an over bore sizr
Now if he could list a part no.

midevil1

iTrader: (17)

He is running a Keith Black piston. Cast or Hyper. Look at the box in the pics for part number.

LS6

Greeting

Regard the Pistons, it is the LS3 with the overbored ones which is 4.0845".

As for the Piston type, it is Silvo Lite as seen in the picture.

Also, the lower half assembeled, the picture is not that good quality.

MRT

82cetuner

iTrader: (9)

better flycut those pistons if you want t orun a descent cam with ls3 heads

LS6

I can not find a piston notching tools from iskycam webpage to buy. It seems it is not manufacting any more.

I have to look for alternative...

MRT

Lifted07Duramax

subbed

how long you thinking til you can fire this up? Another 2 weeks?

Samer

Good luck with your project dude

I know a guy in Dammam who can do flycuts for your pistons.
If it was my engine, I'd flycut the pistons and go for 11.5:1 SCR

LS6

It was this week, but due to urgent work request by the company I'm working in I couldn't complete the project.
However, I'm aiming to fire it by the upcoming two weeks hopfully.

LS6

Samer
I need your help
What value the head shall be milled to get the 11.0 & 11.5 CR with the use stock gasket thickness?
I was planing to get through the long way by milling the heads to 0.030" & then bring a small square glass with a small opening & glue it on one chamber & fill it with water using the medical injection to measure the volume of the chamber. If my memory serve me, a 62cc with stock gasket will provide 11.0 CR & above

LS6

I found very nice article in the Car Craft webpage:

http://www.carcraft.com/techarticles...tio/index.html

How To Calculate Compression Ratio

Surprise! It May Be Lower Than You Think
From the February, 2009 issue of Car Craft



You'd think that the pistons listed for a 10.5:1 compression ratio would actually give you 10.5:1. But it's usually not that simple. Perhaps that's why so many car crafters have a foggy or incomplete understanding of compression ratios. To clear things up, this story will define what compression ratio is, let you know how to alter it, and show you how to calculate it for any engine.


Throughout the story we'll use the example of a typical 350 Chevy (4.000-inch bore, 3.48-inch stroke) with a 0.015-inch deck height, a head gasket with a 4.100 gasket bore and 0.038-inch compressed thickness, 76cc heads, and pistons with 4.5cc valve reliefs--and you'll see what these numbers mean as we go.


What Is Compression Ratio?

Remember what happens during the compression stroke of the four-stroke cycle: Both the intake and exhaust valves are closed so no air can escape, and the piston moves upward from bottom dead center (BDC) to top dead center (TDC) so that the air/fuel mixture in the cylinder is compressed into the combustion chamber. Compression ratio is the relationship of cylinder volume (or displacement) with the piston at BDC to cylinder volume with the piston at TDC. If the volume of the cylinder with the piston at BDC is 10 times greater than the volume of the combustion area with the piston at TDC, then 10 units of volume get squeezed into 1 unit of space, and the compression ratio is 10.0:1.


There are five factors that affect compression ratio: cylinder swept volume, clearance volume, piston dome or dish, head-gasket volume, and chamber volume.



Cylinder Swept Volume

The swept volume of the cylinder indicates how much air the piston displaces as it moves from BDC to TDC. Increasing the cylinder volume without making any other changes will increase the compression ratio because it enlarges the cylinder volume without increasing the combustion chamber volume. In other words, the piston will have to cram more air into the same amount of space. Cylinder volume is calculated using the bore and stroke of the engine with this formula: Cylinder volume = 0.7853982 x bore2 x stroke.


On a standard 350 Chevy, the bore is 4.00 inches and the stroke is 3.48. Apply the formula, and you'll find that one cylinder is 43.730 ci (multiply this times eight cylinders and you get 349.84, which is rounded to 350 for total engine displacement).


If you overbore our sample 350 from 4.00 inches to 4.020 inches and make no other changes, the compression ratio will increase from 8.84:1 to 8.90:1 because the volume of the cylinder has increased. When overboring an engine, the percentage of gain in compression ratio decreases as you add clearance volume and increases as you remove clearance volume, as we'll describe next.


Clearance Volume

Clearance volume is determined by the distance from the cylinder block deck to the top of the piston flat (not counting any dishes or domes) when the piston is at TDC. In many engines, especially 350 Chevys found in cars, the pistons don't come all the way up to the height of the deck--they can be anywhere from 0.003 to 0.020 inch below it. This amount is known as the piston deck height, and it affects compression ratio because it affects the volume of air in the combustion area when the piston is at TDC. If the piston is farther below the deck, then clearance volume is increased and the compression ratio is reduced. If the piston is closer to the deck, clearance volume is reduced and compression ratio is increased.

Here's how to calculate the clearance volume once you know the piston deck height: Clearance volume = 0.7853982 x bore2 x deck height

In our sample 350 with a deck height of 0.015 inch (meaning the top of the piston is 0.015 inch below the deck of the block), the clearance volume is 0.188 ci.


If the deck height of our sample engine was increased to 0.020, compression would drop from 8.84:1 to 8.75:1. If the deck height of our sample engine was decreased to 0.003, compression would increase from 8.84:1 to 9.05:1.


Piston Dome

Note that clearance volume does not take into account any pop-up domes or sunken-in dishes on the head of the piston. These configurations also increase or decrease volume in the combustion chamber and affect the compression ratio. The manufacturer's catalog will list the displacement in cubic centimeters of the dishes or domes on the piston, but we've found that it's not consistent whether they express the cc's of a dish as a positive or a negative number. For the purposes of calculating compression, we prefer to view the cc's of a dish as a positive number because a dish adds volume to the cylinder (and reduces the compression ratio); a dome is a negative number because it subtracts volume from the cylinder (and increases the compression ratio).


Another confusion with piston designations is that they're listed in cubic centimeters, but we use cubic inches to calculate compression ratio. You can convert to cubic inches with this formula: Piston dome or dish in cubic inches = cc's x 0.0610237.


Since our sample engine uses pistons that have 4.5cc dished valve reliefs in them, then they increase the volume of each cylinder by 0.275 ci. If we changed to pistons with a dish of 22 cc (1.34 ci) and made no other changes, then the compression ratio would drop from 8.84:1 to 7.58:1. If we used pistons with a dome of 12 cc (0.73 ci), then the compression would increase from 8.84:1 to 10.56:1.


Head-Gasket Volume

Head-gasket volume is determined by the compressed thickness of the gasket. A thicker gasket adds volume and reduces compression; a thinner gasket reduces volume and increases compression.

A gasket's compressed thickness is listed in the manufacturer's catalog and ranges from 0.051 inch to 0.015 inch. Also, the gasket bore is often larger than the engine bore; a 4.100-inch gasket is common. In our example, we assumed a head gasket with a 4.000-inch bore.

Once you know the compressed thickness and gasket bore, here's how to calculate the volume that the gasket will add to the combustion area: Head-gasket volume = 0.7853982 x gasket bore2 x compressed thickness.


In our example with a 0.038-inch thickness and 4.000-inch bore, the gasket adds 0.478 ci to the volume of the cylinder. If we used a thinner 0.015-inch gasket and made no other changes, the compression ratio would increase from 8.84:1 to 9.27:1.


Chamber Volume

The volume of the combustion chambers is the final factor in determining compression ratio. The larger the chamber, the more volume is added to the cylinder and the lower the compression ratio; smaller chambers reduce volume and increase the compression ratio.


For small-block Chevys, chamber sizes range from around 58 cc to 78 cc. However, the volume of the chambers can vary greatly depending on the type of heads and valves used, the amount the heads may have been milled, the number of valve jobs that have been performed, and any custom chamber grinding that has been done. Manufacturers of cylinder heads will tell you the range of sizes of the chambers in their heads, but for any used or custom-machined heads, the only way to know the size of the chambers is to have a machine shop check. Once this number is known, here's how to convert it from cubic centimeters to cubic inches: Chamber volume in inches = cc's x 0.0610237


Therefore, the 76cc chambers in our 350 have a volume of 4.638 ci. If we were to use cylinder heads with 58cc chambers and make no other changes, the compression ratio would increase from 8.84:1 to 10.72:1.


Add It Up


Once you have all the information listed above, you’re ready to calculate the compression ratio of the engine you’re building. First you add up the volume of the cylinder with the piston at BDC, then divide it by the volume with the piston at TDC.

Here’s the formula:
Compression Ratio =
Cylinder vol. + clearance vol. + piston Comp. vol. + gasket vol. + chamber vol. divided by Clearance vol. + piston vol. + gasket vol. + chamber vol.




Apply this to our example of the Chevy 350 with the 3.48-inch stroke, 4.00-inch bore, 0.015-inch deck height, 0.038-inch head gasket with a 4.000-inch bore, 76cc heads, and 4.5cc dished pistons, and here’s what it looks like: 43.730 + 0.188 + 0.275 + 0.478 + 4.638 divided by 0.188 + 0.275 + 0.478 + 4.638 =8.84:1.



This engine has an 8.84:1 compression ratio. When using this formula, don't forget that the displacement of domed pistons should be expressed as a negative number.

LS6

Now the case I have:

• Engine Bore: 4.0845"
• Engine Stroke: 3.622"
• Gasket Thickness: 0.051" (data from http://www.fbparts.com/ls_general_charts.htm)
• Gasket Bore: 4.100" (Assuming it is 4.100", since I couldn't find this value)
• L92 Cylinder Head Combustion Chamber volume: 70cc (data from http://www.fbparts.com/ls_general_charts.htm)
• Clearance Volume (Distance between the top of piston cylinder to block deck): -0.007" (Many thank to SAMER for his valuable information he provided, Negative value mean the piston is out of or above the block by 0.007" for stock LS block if the deck is not milled)

1. Cylinder Swept Volume: 0.7853982 X Bore X Bore X Stroke = 0.7853982 X 4.0845 X 4.0845 X 3.622 = 47.5 ci
2. Clearance Volume: 0.7853982 X Bore X Bore X Deck Height = 0.7853982 X 4.0845 X 4.0845 X -0.007 = -0.0917"
3. Piston Compression Volume: Assuming it is 0cc since it is flat piston.
4. Head-Gasket Volume: 0.7853982 X Gasket Bore X Gasket Bore X Compressed Gasket Thickness = 0.7853982 X 4.1 X 4.1 X 0.051 = 0.673"
5. Chamber Volume: cc's X 0.0610237 = 70 X 0.0610237 = 4.272"

Compression Ratio (CR) = (Cylinder Swept Volume + Clearance Volume + Piston Compression Volume + Head Gasket Volume + Chamber Volume) / (Clearance Volume + Piston Compression Volume + Head Gasket Volume + Chamber Volume) = (47.5 -0.0917 + 0 + 0.673 + 4.272) / (-0.0917 + 0 + 0.673 + 4.272) = 52.353 / 4.853 = 10.8

The Compression Ratio (CR) is 10.8

Please correct me if I'm wrong...
---------------------------------------------------------------------------------------------------------------------------

Now to get 11.0 : 1

Keeping the item no. 1, 2, 3, 4 the same as above calculation, but changing the item no. 5 from 70cc to 68cc, this will yield the following:

1. Cylinder Swept Volume: 0.7853982 X Bore X Bore X Stroke = 0.7853982 X 4.0845 X 4.0845 X 3.622 = 47.5 ci
2. Clearance Volume: 0.7853982 X Bore X Bore X Deck Height = 0.7853982 X 4.0845 X 4.0845 X -0.007 = -0.0917"
3. Piston Compression Volume: Assuming it is 0cc since it is flat piston.
4. Head-Gasket Volume: 0.7853982 X Gasket Bore X Gasket Bore X Compressed Gasket Thickness = 0.7853982 X 4.1 X 4.1 X 0.051 = 0.673"
5. Chamber Volume: cc's X 0.0610237 = 68 X 0.0610237 = 4.1496"

Compression Ratio (CR) = (Cylinder Swept Volume + Clearance Volume + Piston Compression Volume + Head Gasket Volume + Chamber Volume) / (Clearance Volume + Piston Compression Volume + Head Gasket Volume + Chamber Volume) = (47.5 -0.0917 + 0 + 0.673 + 4.1496) / (-0.0917 + 0 + 0.673 + 4.1496) = 52.2309 / 4.7309 = 11.04



The Compression Ratio (CR) is 11.04
---------------------------------------------------------------------------------------------------------------------------

Now to get 11.6 : 1

Keeping the item no. 1, 2, 3, 4 the same as above calculation, but changing the item no. 5 from 70cc to 64cc, this will yield the following:

1. Cylinder Swept Volume: 0.7853982 X Bore X Bore X Stroke = 0.7853982 X 4.0845 X 4.0845 X 3.622 = 47.5 ci
2. Clearance Volume: 0.7853982 X Bore X Bore X Deck Height = 0.7853982 X 4.0845 X 4.0845 X -0.007 = -0.0917"
3. Piston Compression Volume: Assuming it is 0cc since it is flat piston.
4. Head-Gasket Volume: 0.7853982 X Gasket Bore X Gasket Bore X Compressed Gasket Thickness = 0.7853982 X 4.1 X 4.1 X 0.051 = 0.673"
5. Chamber Volume: cc's X 0.0610237 = 64 X 0.0610237 = 3.90552"

Compression Ratio (CR) = (Cylinder Swept Volume + Clearance Volume + Piston Compression Volume + Head Gasket Volume + Chamber Volume) / (Clearance Volume + Piston Compression Volume + Head Gasket Volume + Chamber Volume) = (47.5 -0.0917 + 0 + 0.673 + 3.90552) / (-0.0917 + 0 + 0.673 + 3.90552) = 51.9868 / 4.4868 = 11.6



The Compression Ratio (CR) is 11.6

chrisfrost

iTrader: (8)

I was wondering what You meant when You calculated the last scr that equalled 11.6/1 because in an earlier post You said You were shooting for 11.0/1 scr then You calculated everything the same except comb chamb changing from 70cc to 68cc equalling 11.04/1 scr in the 2nd scr calculation then in the 3rd scr calculation You did it with everything being the same except the comb chamb changed from 70cc to 64cc equalling 11.6/1 scr . Were You just doing the last 1 as an example 4 poeple to see, read and ultimately gaining a better understanding of how to calculate scr ?

LS6

Greeting


I made the calculation for following two thing:

1. Professional to see and correct if I'm wrong.
2. For other to read & use if the calculation is confirmed is correct.

The three calculations is done to see how the head milling will change the combustion chamber and in return changing the compression ratio by mean of increase.

-The first calculation is made with head is not milled (70cc) that yield 10.8 CR.
-The second calculation is made with head milled to 68cc and yield 11.0 CR.
-The thirdcalculation is made with head milled to 64cc and yield 11.6 CR.

I made a typo mistake, where the last calculation I began with 11.0 while it should be 11.6


Furthermore, one gent advise me that to get the most out of the cam with the L92, the secret is compression ratio. the gentlemen advised to go with 11.5 CR.

Thanks

ausls1

Nice VY SS, iv got one exactly the same colour, but iv got VE SS wheels on mine, got my motor out for a 383 can't wait for it to go back together.

LS6

The commodors V8 is wounderful car & she is a beast when you push it to the limit
The outside look of the commodore when she is in speed action is breathtaking.
Your engine 383ci will be strong. I saw a couple of commodors with 383ci in speed race and it is scary to watch that the car how it goes

ausls1

oh cool, yeh should be good, get the motor back this week, then start putting the rest together, once iv run it in and got used to it and a touch up tune after the initial run in i'll take it to the drag strip and give it a few runs.

elivingston

Did he ever give info on sleeve part#?

LS6

The sleeve is indian made, and it is designed for the diesel engine that have compression ratio of 15.0 : 1.

The sleeve company name is TPS and their part number is 103524 as seen on the packing box in the machine shop.

I will try to take picture of the sleeve packing carton and the sleeve it self for the gents that are requiring this information.

This sleeve comes with two kind, one is with a flanged and other one comes as none flanged sleeve. The shop machined the cylinder block with a ledge at the bottom of the cylinder bores to enable the sleeves to seat and not dropp down toward the crankcase

Thanks

LS6

update:

When installed the melling pump with the double roller timing chain, it was found that it will hit the casing cover which mandate to be trimming the engine side cover to enable the fitment and it is sucessfully done. it was advised by the machine shop to install the melling pump M10355 since I'm planning to have the engine in the operating RPM range of 3500 to 4000 for some times. I know it is not recommended to be used on stock LS1 engine (5.7 Liters --- 346ci), thus I have to check with Melling co. if they advice the usage for the 6.2 Liters.

moreover, due to the fact the piston valve relief cutters are not avilable, we went a head and checked the piston to valve clearance by clary but without using the head gasket, and found almost there is over 0.08" clearance with the custom cam.

The cylinder heads will be milled in couple of steps, and in each step the cylinder heads will be assembled and checked the piston to valve clearance. The first step is the head is milled to 0.25mm (0.01").

As for the engine oil cooler, the mocal cooler adapter if fitted it will not clear for the alternator. Thus, I will be looking for the adapter that are specifically suited for the GTO/Commodor engine car layout.

MRT

LS6

Greeting gent's

The photo's I up loaded in the thread post no. 23 are gone as X

If moderator can help me in this, I would be thankfull

MRT