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Re: Engine build and power


mitsuturbo
Banthony
555/1000


Galant VR-4 org Post #: 956117 posted 12/09/10 12:43 PM     Remind Me!  Send Private Message   Edit Post      
Quoting Muskrat:

</font><blockquote><font class="small">Quote:</font><hr />

289, on sale
That's a good deal if they're local to you. Otherwise shipping is going to put you right back up to ~325.
That's also a far cry from $200. I was just sayin' it's never as cheap as you think it's going to be. EVER.

EDIT: keep in mind, when i said i've never paid less than about 350, it's likely because i WILL NOT have a head rebuilt without REPLACING the 20 year old guides. This also lends to added costs.




Yes. you're right. I'm so sorry for mis-representing the cost of a stock head rebuild. And for not knowing Ross pistons were forged, It completely invalidates my entire post and I will go delete it promptly. Should I also sacrifice my first born to the speed gods to appease you?

Just chill out, there's no need to jump down my throat. A simple, "Hey, it's actually costs $x" Or, "Hey, Ross pistons are actually forged" would suffice.




Sorry man. I'm just pissy because my engine getting dropped into the car is on hold for one measly fucking Alternator Relocate Kit.
I've got some $1600 wrapped up in just my cylinder head, and the mother fucker hasn't even had the chance to fire yet!



92 GVR4 555/1000 11.41 @ 128.26mph
97 CBR900RR
2012 Hyundai Veloster

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Muskrat
Senior Member
665/2000


Galant VR-4 org Post #: 956119 posted 12/09/10 12:47 PM     Remind Me!  Send Private Message   Edit Post      
Np, man. That's a shitty situation. You just got me all defensive.



Brian L.
91 Galant VR-4 #665/2000

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RockstarAgent
Unregistered


Galant VR-4 org Post #: 956131 posted 12/09/10 01:33 PM     Remind Me!  Send Private Message   Edit Post      
Just looking at your signature line: Shouldn't it be Determined Sudomasochistic Mechanic ?

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boostedinaz
Fatty McButterpants
1101/2000


Galant VR-4 org Post #: 956135 posted 12/09/10 01:36 PM     Remind Me!  Send Private Message   Edit Post      
Quoting Drdamm21:

Guy this is all great info my will be the 300.00 frankenstein rods on 2g pistons as well as a full head build going with prev advice for only a 3 angle valve job I might go with custom cams but this will depend on the cost for the total build as im not risk fouling this up. Then I will need to find someone here in arizona who can help me hone and measure for the new pistons ... I can do the rest .. I will get help from michael tuning with my small 16 using dsmlink lite and if it feels good I dont care about the numbers ... Thanks to all




Are you not getting it fully machined and just honing and dropping in new STD size pistons? IMO, that's not going to add to the longevity of the motor and not worth going through all this hassle. In fact once the bore is measured you may find out that it needs to be machined anyway, why not just start with that and KNOW that everything is in spec.



Michael
The rebuild of 1101


Edited by boostedinaz (12/09/10 01:43 PM)

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mitsuturbo
Banthony
555/1000


Galant VR-4 org Post #: 956140 posted 12/09/10 01:57 PM     Remind Me!  Send Private Message   Edit Post      
You can do it on a budget, but please.. at least do it right.
There is a right way, and many wrong ways to "rebuild" an engine.
Haul the block off to the machine shop, and have them bore/hone it to .50mm over (.020"). Have them measure your new pistons beforehand so that they can set PTW clearance right.
If they give you shit about align honing, magnafluxing, squaring the deck, decking the block... you can just say no. Save your money if you know your block is good. Run a stock style head gasket and call it good.

If you do not do it right the first time, you WILL be doing it a 2nd time.



92 GVR4 555/1000 11.41 @ 128.26mph
97 CBR900RR
2012 Hyundai Veloster

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broxma
retard monkey strength
379/1000


Galant VR-4 org Post #: 956147 posted 12/09/10 02:17 PM     Remind Me!  Send Private Message   Edit Post      
Quoting mitsuturbo:

If you know somewhere that will do a full rebuild of a 4g63 head for $200, you'd better let us all in on your secret. I'm sure whoever is doing it would love to have more business.




I get mine done for 183.00 here in San Antonio. That's 16 pressed valve guides, 16 seats, 16 clean valves, decked and tanked. I assemble myself however, but the shop individually numbers each valve with the appropriate spot on the head. I press the seals myself obviously.

I also don't think it is over complicating things to build the motor right, once. The issue is a matter of cost benefit analysis. Look at the typical price for an Eagle/Wiseco piston rod combo on the Ebayz, 750.00ish. A little competitive bargaining can probably drop that closer to 700. So a 1G rod/2G piston combo is upwards of 400.00 either bought outright or DIY, the machine work being the biggest component for the DIY'er. For the extra 300.00, why not? If the motor is already apart, why not just do it once, even over engineered, and be done with it? In addition, someone brought up the low rpm lack of power which is cured by increased compression really, or increased displacement. With any tunable ECU you can run 9.5-1 CR on pump gas, or just go 9-1 CR for those who only get 91 oct. The 8.5-9-9.5 CR Wiseco's all cost the same, so why not? For the extra 300.00 you get forged internals and higher compression. Of course there is machine work technically involved in putting even std. bore forged slugs in the block, but Buschur has been dropping std. bore forged slugs in for years without sending the block of, by just running the ball hone in each cylinder for like 3 minutes, without any failures or problems.

/brox



I am big into recycling though and if your not into sacrifice or burnt offerings, you may want to stick with 93 octane.

/brox

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Justin
Unregistered


Galant VR-4 org Post #: 956161 posted 12/09/10 03:20 PM     Remind Me!  Send Private Message   Edit Post      
Another cheap alternative to gain some compression is to run a 1.8 Hyundai Elantra cylinder head. They are identical in every necessary way to the 2.0 head except they have a smaller combustion chamber. Get it rebuilt instead of the stocker, bolt on all of the stock accessories and use your stock cams. It'll only run $50-$100 more than a stock rebuild, because you've got to buy the thing, but that's it. For your intended power output, this screams bang for the buck. It's a lot cheaper than forged or frankenstein internals.

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boostedinaz
Fatty McButterpants
1101/2000


Galant VR-4 org Post #: 956168 posted 12/09/10 03:36 PM     Remind Me!  Send Private Message   Edit Post      
To build the motor right for what? Usualy the answer to that questions is the goals set forth by the OP. In this case he has stated a power number and a budget. He doesn't want or need (shouldn't put words in his mouth but this is based on our talks)to make 600 AWHP and based on that he doesn't need forged anything. On top of this an extra 300.00 out of a maybe 2500.00 budget is a decent chunck especially when a build like this will already nickel and dime his to death anyway. Now he has a motor that will hold a ton of power but may not be able to buy a gasket kit, or get a good tune on the car but oh man one of these days it will be a beats glad I planned ahead.

This, IMO, is one of the down falls of the DSM community. 16Gs use to be a good turbo, stock short blocks were good enough for most, but now everyone needs forged everything, ported and polished heads, and the smallest turbo available seems to be a 35R. Of course most of these cars never move and even though the turbo and motor can support a bazillion HP most cars never live up to the hype. "My injectors are to small.... my tranny is messed up.... the tune is not 100%" etc....

As I have said a few times now if someone wants to build a beast then do so AFTER the car is on the road and a reliable driver, after all, the is the OP original goal a reliable driver.



Michael
The rebuild of 1101

Posts: 4085 | From: Scottsdale, AZ | Member Since: 04/20/06 | IP: (167.80.246.204) | Report this post to a Moderator

mitsuturbo
Banthony
555/1000


Galant VR-4 org Post #: 956181 posted 12/09/10 03:56 PM     Remind Me!  Send Private Message   Edit Post      
Quoting galant1517:

Another cheap alternative to gain some compression is to run a 1.8 Hyundai Elantra cylinder head. They are identical in every necessary way to the 2.0 head except they have a smaller combustion chamber. Get it rebuilt instead of the stocker, bolt on all of the stock accessories and use your stock cams. It'll only run $50-$100 more than a stock rebuild, because you've got to buy the thing, but that's it. For your intended power output, this screams bang for the buck. It's a lot cheaper than forged or frankenstein internals.




VERY good suggestion. This gets overlooked WAY too often. I knew about it, and even i didn't think about it when i carted a head off to the machine shop.



92 GVR4 555/1000 11.41 @ 128.26mph
97 CBR900RR
2012 Hyundai Veloster

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Drdamm21
Unregistered


Galant VR-4 org Post #: 956192 posted 12/09/10 05:26 PM     Remind Me!  Send Private Message   Edit Post      
Man did I say hone only I meant machine work added cost but its needed after 176k and lucky for me it ceased at the crank but im having my crank looked at to make sure I can use it again.... Thank you all for the help so im gonna just build a good engine then if I have any money left out of my 2500 budget I will get a few goodies

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cheekychimp Galant VR4.org Moderator
Director of Housing and Urban Development, and carbon/kevlar balls


Galant VR-4 org Post #: 956347 posted 12/10/10 10:10 AM     Remind Me!  Send Private Message   Edit Post      
Quoting galant1517:

Another cheap alternative to gain some compression is to run a 1.8 Hyundai Elantra cylinder head. They are identical in every necessary way to the 2.0 head except they have a smaller combustion chamber. Get it rebuilt instead of the stocker, bolt on all of the stock accessories and use your stock cams. It'll only run $50-$100 more than a stock rebuild, because you've got to buy the thing, but that's it. For your intended power output, this screams bang for the buck. It's a lot cheaper than forged or frankenstein internals.




Quoting mitsuturbo:

VERY good suggestion. This gets overlooked WAY too often. I knew about it, and even i didn't think about it when i carted a head off to the machine shop.




Can either of you give me a little more information on this head as I don't believe we get that particular vehicle here in Asia. Is this head essentially a 1G or 2G head and how much more compression would it give? I am wondering what would happen if you were to use this head in conjunction with a 9.0 or 9.5 CR. Would it end up too high?



Getting old sucks ... but it sure beats the alternative !!!

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mitsuturbo
Banthony
555/1000


Galant VR-4 org Post #: 956365 posted 12/10/10 11:25 AM     Remind Me!  Send Private Message   Edit Post      
There is a difference of 4cc between the heads. I'm not sure what that would equate to as far as static Compression Ratio.



92 GVR4 555/1000 11.41 @ 128.26mph
97 CBR900RR
2012 Hyundai Veloster

Posts: 3537 | From: Near Seattle, Washington | Member Since: 06/02/08 | IP: (130.76.32.208) | Report this post to a Moderator

2of9
Hellaflush


Galant VR-4 org Post #: 956369 posted 12/10/10 11:44 AM     Remind Me!  Send Private Message   Edit Post      
Not sure if this helps but I will throw here anyways.

I'm not sure what your power goals are but I'm doing pretty well with my stock 6 bolt bottom end. Previous owner rebuild the bottom end, rings, bearings, bored .020 over, etc. Pistons are still original and so are the rods @ 225,000 miles! WOOT WOOT! Anyways, just make sure it's built correctly. Maintenance is #1. I've been told that the stock blocks were able to push over 400hp...but haven't personally seen one yet. As for mods, Evo3 16g, 2g manifold, 3" exhaust system, 550cc, 190, fmic w/ solid IC pipings, act 2100, HKS mega airflow MAS, DSMLink v2.

3 Years ago, the car dyno'd at 199awhp/203awtq with the big 16g, stock IC, crappy street tune with afr's spiking to 14 at the 5.5k mark . I'm positive with a good tune now and the mods I have, I should be in the 250-260 range or more...depending on the dyno I go to. I tell you now, the car is REALLLLLLY fun as it is. I can't imagine how much more fun it can be if I can go with e85 + FP HTA68 + 1000cc injectors + 255 fuel pump + tune. I know that my trans won't be able to hold it though lol.



Team Nines DSM Specialist


Edited by 2of9 (12/10/10 11:51 AM)

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DR1665
Kill him in the face with Wilson Phillips


Galant VR-4 org Post #: 956392 posted 12/10/10 12:44 PM     Remind Me!  Send Private Message   Edit Post      
This thread makes me sad.

1. What was once among the cleanest GVR4s around has been passed around and fucked by something like a half-dozen irresponsible, knuckle-dragging fucktards.
2. 1101 finally gets back into the hands of someone who just wants to drive it, and it shits the bed.
3. New owner gets bombarded with every Frankenstein clusterfuck contingency plan surefire way to "do it right."

How about this. I have a 99% stock 6-bolt collecting dust on an engine stand at 51st Ave and Thunderbird. It's got less than 10,000 miles on a fresh - STOCK - rebuild. Honed cylinders, fresh rings and bearings. Head cleaned up and serviced prior to being re-installed with a Mitsubishi MLS head gasket. New valve seals, intake/exhaust ports gasket matched and lightly cleaned up. Does not leak a drop of oil. Does not overheat. Only reason it's out is because some retard ran a red light and I caught him in the B-pillar doing about 45mph. Car is being stripped/prepped for a roll cage.

Fuck all this noise. You've got a $2500 budget? I'll trade you straight up - your boat-anchor engine & $1000 for mine. Put a grand in my hand, pick up the engine in the morning, drive 1101 that night with $1500 in your pocket to play with.

Just throwing another idea out there.



Brian | 98 Pajero | Gearbox Magazine


Edited by DR1665 (12/10/10 12:45 PM)

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mitsuturbo
Banthony
555/1000


Galant VR-4 org Post #: 956394 posted 12/10/10 12:45 PM     Remind Me!  Send Private Message   Edit Post      
I like this idea, and i support it.



92 GVR4 555/1000 11.41 @ 128.26mph
97 CBR900RR
2012 Hyundai Veloster

Posts: 3537 | From: Near Seattle, Washington | Member Since: 06/02/08 | IP: (130.76.32.198) | Report this post to a Moderator

boostedinaz
Fatty McButterpants
1101/2000


Galant VR-4 org Post #: 956398 posted 12/10/10 12:54 PM     Remind Me!  Send Private Message   Edit Post      
Quoting DR1665:

This thread makes me sad.

1. What was once among the cleanest GVR4s around has been passed around and fucked by something like a half-dozen irresponsible, knuckle-dragging fucktards.
2. 1101 finally gets back into the hands of someone who just wants to drive it, and it shits the bed.
3. New owner gets bombarded with every Frankenstein clusterfuck contingency plan surefire way to "do it right."

How about this. I have a 99% stock 6-bolt collecting dust on an engine stand at 51st Ave and Thunderbird. It's got less than 10,000 miles on a fresh - STOCK - rebuild. Honed cylinders, fresh rings and bearings. Head cleaned up and serviced prior to being re-installed with a Mitsubishi MLS head gasket. New valve seals, intake/exhaust ports gasket matched and lightly cleaned up. Does not leak a drop of oil. Does not overheat. Only reason it's out is because some retard ran a red light and I caught him in the B-pillar doing about 45mph. Car is being stripped/prepped for a roll cage.

Fuck all this noise. You've got a $2500 budget? I'll trade you straight up - your boat-anchor engine & $1000 for mine. Put a grand in my hand, pick up the engine in the morning, drive 1101 that night with $1500 in your pocket to play with.

Just throwing another idea out there.




This is a great deal and I'll 110% vouche for Brian as being a super stand up guy.



Michael
The rebuild of 1101

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mitsuturbo
Banthony
555/1000


Galant VR-4 org Post #: 956427 posted 12/10/10 02:18 PM     Remind Me!  Send Private Message   Edit Post      
There ya go. Problem solved.
Werd.. get yer ass to 51st and thunderbird.



92 GVR4 555/1000 11.41 @ 128.26mph
97 CBR900RR
2012 Hyundai Veloster

Posts: 3537 | From: Near Seattle, Washington | Member Since: 06/02/08 | IP: (130.76.32.216) | Report this post to a Moderator

Justin
Unregistered


Galant VR-4 org Post #: 956446 posted 12/10/10 03:29 PM     Remind Me!  Send Private Message   Edit Post      
Quoting cheekychimp:


Can either of you give me a little more information on this head as I don't believe we get that particular vehicle here in Asia. Is this head essentially a 1G or 2G head and how much more compression would it give? I am wondering what would happen if you were to use this head in conjunction with a 9.0 or 9.5 CR. Would it end up too high?




The head is a 1G head, with 1G runners and 1G CAS provisions. As mitsuturbo stated, the combustion chamber is 4cc smaller, it also has the same size valves and it accepts the 1G external components (intake, v/c, t-stat housing). The engine designation would be a 4G67, so you could look at any vehicle so equipped in your market. Rumor has it that JDM 4G61T's also used this head. The USDM 4G61T's got the small runner version I believe. Someone way better at math could easily figure out the difference in CR with the right equation, but I'd suspect that it would add 5 tenths at the very most.


Edited by galant1517 (12/12/10 12:18 PM)

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Justin
Unregistered


Galant VR-4 org Post #: 956449 posted 12/10/10 04:22 PM     Remind Me!  Send Private Message   Edit Post      
Taken from www.carcraft.com
Quote:

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, youre ready to calculate the compression ratio of the engine youre 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. Heres the formula:

Compression Ration =

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.



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Drdamm21
Unregistered


Galant VR-4 org Post #: 956491 posted 12/10/10 06:31 PM     Remind Me!  Send Private Message   Edit Post      
Hey guys im getting ready to put my motor on the enginge stand michael let me borrow and I cant seem to seperate the damn tranny its pissing me off it just moves left to right and is about a half inch away from the block but wont seperate .... Any help what am I missing

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DR1665
Kill him in the face with Wilson Phillips


Galant VR-4 org Post #: 956681 posted 12/11/10 02:33 PM     Remind Me!  Send Private Message   Edit Post      
If the bellhousing is separated from the block, it's all a matter of getting the engine and transmission far enough apart that the clutch will clear the bellhousing. You may need to re-figure how you have the engine hanging on the picker. It might just be easier to pull the engine/trans together.

As you're lifting it all out with the cherry picker, set your chains to allow the whole thing to angle downward on the transmission side. With the engine higher, the angle makes it easier to get it all clear of the sidemembers in the engine bay.



Brian | 98 Pajero | Gearbox Magazine


Edited by DR1665 (12/12/10 01:49 PM)

Posts: 4631 | From: Phoenix, AZ | Member Since: 10/19/05 | IP: (68.2.218.42) | Report this post to a Moderator

mitsuturbo
Banthony
555/1000


Galant VR-4 org Post #: 956693 posted 12/11/10 04:10 PM     Remind Me!  Send Private Message   Edit Post      
Quoting galant1517:

Quoting cheekychimp:


Can either of you give me a little more information on this head as I don't believe we get that particular vehicle here in Asia. Is this head essentially a 1G or 2G head and how much more compression would it give? I am wondering what would happen if you were to use this head in conjunction with a 9.0 or 9.5 CR. Would it end up too high?




The head is a 1G head, with 1G runners and 1G CAS provisions. As mitsuturbo stated, the combustion chamber is 4cc smaller, with same size valves and it accepts the 1G external components(intake, v/c, t-stat housing). The engine designation would be a 4G67, so you could look at any vehicle so equipped in your market. Rumor has it that JDM 4G61T's also used this head. The USDM 4G61T's got the small runner version I believe. Someone way better at math could easily figure out the difference in CR with the right equation, but I'd suspect that it would add 5 tenths at the very most.




Well, as a point of reference, i've got Mahle pistons with a 13cc dish. CR is 8.5:1 (published)
They're also selling some with a 10cc dish now. They're listed at 9:1 CR.

3cc difference = +.5 CR difference
in stock bore, i assume
maperformance lists 1mm os pistons as being 9.2:1 rather than 9:1, which illustrates how bore can affect compression as well



92 GVR4 555/1000 11.41 @ 128.26mph
97 CBR900RR
2012 Hyundai Veloster

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Justin
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Galant VR-4 org Post #: 956762 posted 12/11/10 09:17 PM     Remind Me!  Send Private Message   Edit Post      
^^^like I said, someone way better at math. I could be way off base here, but it would seem that compression increases aren't linear, that they occur on a curve. I.E; when starting with a larger dished piston, the increase is smaller. If you have a smaller dished piston, the increase is larger.


Edited by galant1517 (12/11/10 09:18 PM)

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Barnes
Firechicken
908/1000
237/2000


Galant VR-4 org Post #: 956768 posted 12/11/10 09:37 PM     Remind Me!  Send Private Message   Edit Post      
Compression ratio linearly increases or decreases as piston dome volume increases or decreases respectively.
Compression ratio linearly increases or decreases as piston dish volume decreases or increases respectively.

EDIT: THIS INFORMATION IS INCORRECT!



-Jon Barnes
#580/2000 (Long Gone)
#908/1000 Black (Sold)
#237/2000 White


Edited by BarnesMobile (12/13/10 03:54 PM)

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Justin
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Galant VR-4 org Post #: 956829 posted 12/12/10 01:18 AM     Remind Me!  Send Private Message   Edit Post   
Barnesmobile, I unfortunately have to say you are incorrect sir. After doing the math, here are my results.

88 / 25.4 = 3.46 (stroke)
85 / 25.4 = 3.35 (bore)

0.7853982 x (3.35 x 3.35) x 3.46 = 30.496894 (cylinder swept volume)

For simplicity, I've left piston to deck height and H/G compressed volume values at 0, because they are not variables in our equation. This leaves only combustion chamber volume and piston dish volume to take into account, which when combined will give us a net value of total combustion volume.

Remember that I'm not taking into account the piston to deck height clearance or the head gasket compressed volume, so these numbers ARE NOT ACTUAL COMPRESSION RATIO'S FOR GIVEN PISTON DISH VOLUMES.

Assuming we are working with a 47cc cylinder head, and a 13cc piston dish, we see that the total combustion volume(TCV) is 60cc.

60 x 0.0610237 = 3.6614220

(30.496894 + 3.6614220) / 3.6614220 = 9.3292486:1 CR

With a 10cc dish, TCV is 57cc.

57 x 0.0610237 = 3.4783509

(30.496894 + 3.4783509) / 3.4783509 = 9.7675438:1 CR, an increase of 0.4382952 CR.

A 7cc dish equals 54cc TCV.

54 x 0.0610237 = 3.2952798

(30.496894 + 3.2952798) / 3.2952798 = 10.254721:1 CR, an increase of 0.4871772 CR.

A 4cc dish equals 51cc TCV.

51 x 0.0610237 = 3.1122087

(30.496894 + 3.1122087) / 3.1122087 = 10.799116:1 CR, an increase of 0.544395 CR.

Clearly, with everything else being equal, simply subtracting 3cc of piston dish volume will not yield an equal increase of CR every time. As I said before, the bigger the dish, the smaller the increase. Smaller dish, greater increase.


Edited by galant1517 (12/12/10 12:25 PM)

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