Ok so I did a little searching and I found some interesting information... hopefully someone can verify my info and fill in the blanks...
I always hear from my Honda-boy buddies about how they buy their Mugen or Spoon head gaskets to raise their compression by a few hundredths... That seems like quite a big change just by swapping in a thinner head gasket. Do Honda's just use oddly thick stock gaskets or what? Also, is there some way of calculating the relationship between head gasket thickness and compression ratio? I would think the relationship would be linear.
That leads me to my other questions... closer to home. What thickness are stock 2.2L Ecotec head gaskets? I have read the Cometic gasket from JTuners is .030"... how much thinner is this than stock? How much of an increase in compression would this yield? Would it be worth the hassle?
Thanks in advance for any info.
The cometic gaskets come in a couple diff thickness levels for boost and NA applications. say for example the 2200 gasket is .040 stock and the NA cometic gasket is .030. So that will infact change the compression a bit.
Well I kinda know it will change the compression... I'd like to find out how much it'll change though... I suppose my question could be more simplified by saying that the Honda-boys consider the Spoon or Mugen head gaskets to be a performance upgrade by themselves... would we consider the Cometic to be a performance upgrade by themselves or only to suppliment other upgrades?
Wouldn't that lower the compression if you got a smaller gasket?
I mean, doesn't compression have to deal with how close your pistons are to your gasket/cylinder head? The bigger your pistons are, the closer they are to your cylinder head, the higher compression you are running. Now...if you get a skinnier gasket, that would make the distance between the piston even more...so wouldn't that lower the compression?
Maybe I'm missing something...
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Tim wrote:Well I kinda know it will change the compression... I'd like to find out how much it'll change though... I suppose my question could be more simplified by saying that the Honda-boys consider the Spoon or Mugen head gaskets to be a performance upgrade by themselves... would we consider the Cometic to be a performance upgrade by themselves or only to suppliment other upgrades?
I guess but like Phlatcav said, it depends on what size gasket you get.
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it's not how big the pistons are, it's how small the combustion chamber and the piston dish are.
If you get a thinner head gasket, the CC of the combustion chamber and the head gasket will be smaller but you'll still be pushing the same amount of air/fuel(3.1416/4(*bore*bore)*stroke) so the compression will be higher. not enough to buy a thinner head gasket IMO.
Gilles
2.3 Ho
Mfk-223 wrote:it's not how big the pistons are, it's how small the combustion chamber and the piston dish are.
If you get a thinner head gasket, the CC of the combustion chamber and the head gasket will be smaller but you'll still be pushing the same amount of air/fuel(3.1416/4(*bore*bore)*stroke) so the compression will be higher. not enough to buy a thinner head gasket IMO.
Thank you for the explination
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specs on the 2.4/LD9, and a link for a calculator........ if you can find your engine's info, enter it into the calculator...... it will then calculate your compression. More compression, more heat, more power........
LD9
Bore in: 3.54
Stroke in: 3.70
Head cc's: 60
Gasket Thickness in: 0.047
Deck Height (Put .0001 for zero deck) in: .0001
Dish or Valve Pocket [-] or Dome [+] cc's: -2.6
Number of Cylinders: 4
http://www.rosspistons.com/calculator.php
SPD RCR Z -
'02 Z24 420whp
SLO GOAT -
'04 GTO 305whp
W41 BOI -
'78 Buick Opel Isuzu W41 Swap
oh yea, thats for the 96-98 LD9, the 99+ has a 0.0 dish..... and I think the head might have a different CC....
SPD RCR Z -
'02 Z24 420whp
SLO GOAT -
'04 GTO 305whp
W41 BOI -
'78 Buick Opel Isuzu W41 Swap
Your all right. Compression depends on the size of the bore, the top of the piston, the ring landings, the compressed gasket thickness, the size of the combustion chamber.
All go together to give you your CR. Easiest thing to do would be either a thiner gasket or mill the head, but with either of these you NEED to check and make sure your pushrod legth is correct and that you don't have any piston to valve contact. I recomend a knowledgable machine shop who KNOWS youe engine and what they an do, If not
BOOM ! ANd thats no fun at all.
Good Luck.
Semper Fi SAINT. May you rest in peace.
eh, Sunfires... (Tom) wrote:NJHK (The JBO Negro) wrote:Wouldn't that lower the compression if you got a smaller gasket?
I mean, doesn't compression have to deal with how close your pistons are to your gasket/cylinder head? The bigger your pistons are, the closer they are to your cylinder head, the higher compression you are running. Now...if you get a skinnier gasket, that would make the distance between the piston even more...so wouldn't that lower the compression?
Maybe I'm missing something...
Whaaaa 
Evidentally I sound confussed. Instead of saying "whaaa" why not fill me in? It's easy to say a pointless comment.
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NJHK (The JBO Negro) wrote:eh, Sunfires... (Tom) wrote:NJHK (The JBO Negro) wrote:Wouldn't that lower the compression if you got a smaller gasket?
I mean, doesn't compression have to deal with how close your pistons are to your gasket/cylinder head? The bigger your pistons are, the closer they are to your cylinder head, the higher compression you are running. Now...if you get a skinnier gasket, that would make the distance between the piston even more...so wouldn't that lower the compression?
Maybe I'm missing something...
Whaaaa
Evidentally I sound confussed. Instead of saying "whaaa" why not fill me in? It's easy to say a pointless comment.
A thinner gasket would make the piston to head distance less, not more. It's like a sandwich, with the gasket being the meat. If you have less meat, the slices of bread are closer together.
fortune cookie say:
better a delay than a disaster.
If you want to bump compression, do the mods to the block and swap the 086 head on. There is 11.4:1 compression right there.
I was a retard, and now I'm permanently banned.
OHV notec wrote:NJHK (The JBO Negro) wrote:eh, Sunfires... (Tom) wrote:NJHK (The JBO Negro) wrote:Wouldn't that lower the compression if you got a smaller gasket?
I mean, doesn't compression have to deal with how close your pistons are to your gasket/cylinder head? The bigger your pistons are, the closer they are to your cylinder head, the higher compression you are running. Now...if you get a skinnier gasket, that would make the distance between the piston even more...so wouldn't that lower the compression?
Maybe I'm missing something...
Whaaaa
Evidentally I sound confussed. Instead of saying "whaaa" why not fill me in? It's easy to say a pointless comment.
A thinner gasket would make the piston to head distance less, not more. It's like a sandwich, with the gasket being the meat. If you have less meat, the slices of bread are closer together.
Ok thank you. For some reason I was thinking the opposite way but i was still somewhat on the right frame of mind.
Thanks again.
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11.4:1 ? Hello Cam 2 !
Semper Fi SAINT. May you rest in peace.
Ok so this post confused what i was thinking, for Boost is higher compression better or lower compression?
Play hard, Drive fast, and Be safe...
For boost you want a compression around 9:1. For N/A with cams and head work you wanna bumpt he compression up 10:1+. Dont listen to honda Boys regardless. Going though all the work and cost (if you cant do the work yourself) is not worth it. If you gain another 2 hp on a stock setup I would be surprized.
Easy way to think about compression, its the volume of the Cylinder at bottom dead center : the volume of the cylinder at top dead center. Anything you do inside of the chamber affects compession. Pistons, heads, head gaskets, valves...... I think you get the point.
2002 Z28: Slp coldair Pac, Corsa Catback, 3200 stall
Thanks, fats
Play hard, Drive fast, and Be safe...
the cometic headgaskets for the ecotec have a thickness of .040 in BTW and come in 87,89, and 92mm bore sizes
I used to race cars, now I race myself.
5K PB: 24:50
10K PB: 54:26
Cometic lists 11 different thicknesses for their head gaskets, from.027" to .120". The most common carried an manufactured is the .040", but from what I gather from their web site, you can get one made in whatever thickness you want. Once they have the pattern, they can cut the center layer in different thicknesses to accomidate your needs.
You can use a thinner gasket to raise the compression or a thicker one to lower your compression, just as stated above. With a boosted motor, you would want to lower the compression as low as the compressor is capable keeping up. It's not uncommon to see C/Rs as low as 7:1 on motors with monster boost. Using a lower C/R will allow for more boost, with less chance of detonation, resulting in more power and torque.
On the OHC motors, be careful not to go too thick or too thin, you don't want too much slack or too much tension on the timing chain. On the OHV motors you can adjust a little with an adjustable valve train (roller rocker conversion), but only for a few thousandths, or with custom length push rods.
According to on manual I've got, the compressed gasket thickness on the 2.2 OHV was .055". Reducing the gasket thickness to .036" would raise the C/R about 4 tenths. Not necessarily something to a stock motor, but worth a look if you're rebuilding it.
something to remember though, while raising the C/R buy surfacing the block, you must maintain at least .035" to.040" piston to head clearance with steel connecting rods. This is to maintain the proper quench clearance between the piston and cylinder head. This clearance can be done with the head gasket and / or deck clearance.
I did play with a C/R calculator and found that if you zero deck the block of a 2.2 OHV, with stock replacement pistons and a .036" head gasket, you would get a C/R of approximately 10.1:1. Of course, I would use the Silv-O-Lite hypereutectic pistons (part # 3422h) for a little more durability with that C/R.
I guess I should have specified that I was looking for info on the 2.2L Ecotec... Lotta info coming in on the OHV motor. The thing is, I want to know how much the compression would go up on a stock 2.2L DOHC Ecotec if I installed the Cometic .030" head gasket found
here. If anyone could figure this out and let me know, I would greatly appreciate it.
NJHK (The JBO Negro) wrote:OHV notec wrote:NJHK (The JBO Negro) wrote:eh, Sunfires... (Tom) wrote:NJHK (The JBO Negro) wrote:Wouldn't that lower the compression if you got a smaller gasket?
I mean, doesn't compression have to deal with how close your pistons are to your gasket/cylinder head? The bigger your pistons are, the closer they are to your cylinder head, the higher compression you are running. Now...if you get a skinnier gasket, that would make the distance between the piston even more...so wouldn't that lower the compression?
Maybe I'm missing something...
Whaaaa
Evidentally I sound confussed. Instead of saying "whaaa" why not fill me in? It's easy to say a pointless comment.
A thinner gasket would make the piston to head distance less, not more. It's like a sandwich, with the gasket being the meat. If you have less meat, the slices of bread are closer together.
Ok thank you. For some reason I was thinking the opposite way but i was still somewhat on the right frame of mind.
Thanks again.
It is easier to make a random pointless comment than a sorted long essay of how less gskt thickness means more compression. Now it's a little late to write that essay. Refer to ohv notec's metaphor.
eh, Sunfires... (Tom) wrote:NJHK (The JBO Negro) wrote:OHV notec wrote:NJHK (The JBO Negro) wrote:eh, Sunfires... (Tom) wrote:NJHK (The JBO Negro) wrote:Wouldn't that lower the compression if you got a smaller gasket?
I mean, doesn't compression have to deal with how close your pistons are to your gasket/cylinder head? The bigger your pistons are, the closer they are to your cylinder head, the higher compression you are running. Now...if you get a skinnier gasket, that would make the distance between the piston even more...so wouldn't that lower the compression?
Maybe I'm missing something...
Whaaaa
Evidentally I sound confussed. Instead of saying "whaaa" why not fill me in? It's easy to say a pointless comment.
A thinner gasket would make the piston to head distance less, not more. It's like a sandwich, with the gasket being the meat. If you have less meat, the slices of bread are closer together.
Ok thank you. For some reason I was thinking the opposite way but i was still somewhat on the right frame of mind.
Thanks again.
It is easier to make a random pointless comment than a sorted long essay of how less gskt thickness means more compression. Now it's a little late to write that essay. Refer to ohv notec's metaphor.
No one is asking you to make an essay. Ultimately what I'm saying is that comment didn't help anything or anyone and essentially was just negative. If you see that someone doesn't understand something and you know what the correct way is, why not take the time to give them a brief understandment? Like you said, OHV Notec took a small paragraph to explain it...is that so hard?
But whatever, I'm over it. Me personally, if I see that someone doesn't understand something, I don't make fun or make silly little comments that are negative, I HELP them to understand...that's what this place is all about, helping others and educating others. If you didn't have anything useful to say, you shouldn't have said it.
/end rant
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