Thinner head gasket results

[outlawbusa]

What kind of compression difference does a thinner head gasket actually make. Would it be comparible to running MR12 fuel with a gain of about 6-8~ hp or would it be much less?

2nd question...how would it affect a nitrous bike vs a stock bike?

 

[mr8ball]

The thinner gasket would give it more compression. Depends on how thin you go depends the HP gain. I would not recommend it on a nitrous bike. It might burn through and really cause some damage. Of course when you change the head gasket you have to watch the piston to valve clearance. Back when I use to build motors I think .100 was as close as we could go on that. You do have some float in the valve but at .100 we never had one hit the piston. I am sure things have changed since I was doing that kind of work but we ran everything as close as we could for the HP

 

[outlawbusa]

I am putting a stock head back on until at least Spring and should not have any clearance issues at all using stock cams with a .018 head gasket...right~?~

I am curious about HP, realistic maybe 2-3 HP or do you think it may actually give a couple more~?~

 

[mestona]

I don't think you will get an accurate HP estimate, most people don't open up their engine just to change to a thinner head gasket. The only real way to guess (short of getting before and after dyno pulls) is to get the cc volume of the stock head gasket, get the cc volume of the thinner head gasket, subtract the difference, calculate the compression increase and apply the formula of (4% power increase x compression increase x original horsepower = horsepower increase). Horsepower increases an average of 4% per point of compression increased:

Example: .04 x .5 (half a point of compression increase) x 175 (aprox stock hp of a gen2) = 3.5 HP gain
3.5 Gain + 175 Stock = 178.5 HP total (just an example)

Another option is to go with a thinner base gasket or no base gasket and silicone/ decked and o-ringed block

 

[mr8ball]

I am putting a stock head back on until at least Spring and should not have any clearance issues at all using stock cams with a .018 head gasket...right~?~

I am curious about HP, realistic maybe 2-3 HP or do you think it may actually give a couple more~?~

I feel you would be Ok on that but as far as the HP it is really no way to tell what the real gain would be unless you dyno it both ways. It has been quite a while since I have done any of this type of work but still feel sure I am right on what I am saying. I have a good friend that works for Kowalsky Machine and he use to build all of the Pro Stock motors for Sonnys Automotive here in Lynchburg. If you send me all your specks I feel sure he could figure everything out for you. PM or email me if you like. email is mr8ballme@gmail Doug

 

[Professor]

Don't forget the valve timing will change as well.

 

[mestona]

Also with nitrous, anytime you increase cylinder pressure, you need to pull timing to prevent detonation. This would be far more critical than with the NA motor.

 

[outlawbusa]

Don't forget the valve timing will change as well.

Also with nitrous, anytime you increase cylinder pressure, you need to pull timing to prevent detonation. This would be far more critical than with the NA motor.

The nitrous question was for Tofas2c's bike but I believe we ruled that out and he'll stick with the stock size gasket.

My bike though, will be all stock engine and head and NA. Will I still need to change timing just with a thinner gasket~?~

That'll be an important answer to know because we race Maxton in a couple weeks. Swapping heads this weekend.

 

[outlawbusa]

all stock engine and head and NA. Will I still need to change timing just with a thinner gasket~?~

That'll be an important answer to know because we race Maxton in a couple weeks. Swapping heads this weekend.

Can anyone elaborate on the timing with a thinner head gasket. I always run 93 octane on the street and lately we've been running 100 octane at Maxton. Do you think I will run into detonation issues~?~

 

[mestona]

It is unlikely with 100octane that you will see detonation as long as your map is up to spec. As far as the timing goes, as you shorten the height of the head (thinner head gasket = shorter engine overall, even if it is a very minor amount) which effectively lengthens your timing chain. You might need adjustable cam sprockets depending on how far off your cam timing turns out to be. You won't know until you assemble it and degree the cams.

 

[Got-Busa?]

Yep, I don't think its worth the trouble unless you make other changes while its apart...

 

[outlawbusa]

Yep, I don't think its worth the trouble unless you make other changes while its apart...

I just purchased another head so it's being swapped anyway for the Winter so I can go through the one on it now. Anyway, I have an OEM gasket and a .018 gasket sitting in a drawer in my garage so I figure why not put the .018 gasket on for a while. It's going to happen either way, just wanting to know what to expect...but like someone said, who does just that mod and takes down a number or results. Wishful thinking I guess.

 

[tofas2c]

To ad a question to this can you go with no base gasket and a .018 head gasket. With stock pistons, and cams. Will there be enought clearance and will last. I just melted a piston in Ohio over the weekend with a little to much Nitrous or should i say not enough gas. LOL. I know not to spray much with the thinner gasket but I dought if i spay if to at least another year. So can this be done and will it be worth the HP?