thinner or thicker head gasket?
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Honda-Tech Member
Joined: Oct 2001
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From: Nowhere, New York, USA
Re: (Audiojb)
Hi,
Its really not worth pulling the head just to use a slightly thinner headgasket. You won't gain that much in compression.
If you pull the head you should get it skimmed a few thousandths to make sure that it will seal properly. If you are going to skim it, you might want to take off enough to make a difference in compression.
The problem with that is twofold. It will retard your valve timing, so you'll need adjustable cam gears. It will also limit your piston to valve clearance in case you wanted to go with some really zippy cams.
However, if you go with really zippy cams, due to the overlap you will lose effective compression. In that case, you may need high compression pistons. On and on it goes.
Really decide what you want before you go there.
John
Modified by Racebrewer at 4:41 AM 4/25/2008
Its really not worth pulling the head just to use a slightly thinner headgasket. You won't gain that much in compression.
If you pull the head you should get it skimmed a few thousandths to make sure that it will seal properly. If you are going to skim it, you might want to take off enough to make a difference in compression.
The problem with that is twofold. It will retard your valve timing, so you'll need adjustable cam gears. It will also limit your piston to valve clearance in case you wanted to go with some really zippy cams.
However, if you go with really zippy cams, due to the overlap you will lose effective compression. In that case, you may need high compression pistons. On and on it goes.
Really decide what you want before you go there.
John
Modified by Racebrewer at 4:41 AM 4/25/2008
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Junior Member
Joined: Mar 2008
Posts: 35
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From: Andover, MN
Re: (Racebrewer)
thanks. what im planning on doing is to do a fully built motor and do all the valvetrain and pistons etc. then. im not pulling off the head just to put a head gasket on.
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Joined: Oct 2001
Posts: 419
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From: Nowhere, New York, USA
Re: (mrbutters)
Hi,
Good thinking. People will put in BIG cams and go slower because they lose compression due to the valve overlap (both valves open at once).
If you go with really hot cams you will need larger injectors and a new ECU or piggyback. Nice thing about VTEC is that you can often find cams where the lower rpm lobes are close to stock ITR so it retains very good driveability.
BTW, If you shift your powerband upwards too much, you will have to change your gearing to get it to work.
There are a lot of things to consider. Remember, you are working with a system. All of the various things such as flow, lift, compression, etc, etc, all interact and not to the best.
Remember, also, to keep in mind what quality of gas is available and your state's inspection laws. And, of course, $$$$$$$$$$$.
John
Good thinking. People will put in BIG cams and go slower because they lose compression due to the valve overlap (both valves open at once).
If you go with really hot cams you will need larger injectors and a new ECU or piggyback. Nice thing about VTEC is that you can often find cams where the lower rpm lobes are close to stock ITR so it retains very good driveability.
BTW, If you shift your powerband upwards too much, you will have to change your gearing to get it to work.
There are a lot of things to consider. Remember, you are working with a system. All of the various things such as flow, lift, compression, etc, etc, all interact and not to the best.
Remember, also, to keep in mind what quality of gas is available and your state's inspection laws. And, of course, $$$$$$$$$$$.
John
Thread Starter
Junior Member
Joined: Mar 2008
Posts: 35
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From: Andover, MN
Re: (Racebrewer)
yeah. thanks alot for your advice. but is there any way to tell when buying cams that it well mess with the powerband too much? and what duration would you reccomend on cams for itr's. thanks for your help.
Junior Member
Joined: May 2007
Posts: 32
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From: Toronto, ON, Canada
Re: (mrbutters)
if your interested I have a buddy club full head package for sale, I have spec 4 Camshafts, b18c5 Cam gears, valve, salve springs and retainers all made by buddy club, there brand new in box never installed. Ill be letting them go for $1200 CDN if your interested contact me
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Joined: Oct 2001
Posts: 419
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From: Nowhere, New York, USA
Re: (mrbutters)
Hi,
Cam selection depends upon what you want to do with the car and how much money you have/how extreme you want to go. A car is a system. All the factors need to work together.
In a naturally asperated motor as the cams get 'hotter' there is a physical loss of compression due to overlap. To compensate you have to increase static compression. This will make the cams work. The cams also raise and narrow the powerband so you have to rev higher and change the gearing and shift more often.
In the late 1960's, Honda built some incedibly powerful Formula One engines. Their powerband was incrediby peaky and to make the powerband useful they had to have 17 speed gearboxes. The driver had to shift thousands of times per race.
Most people look at what is easiest to do first and cams are one of those things. Cams should be the last thing you do, if you do things in steps as you can afford them. If you can do it legally, the very first thing you should actually look at is a programable ECU to control what the motor is doing along with an EGT and a wideband AFR to monitor it. There are some very good ECU's out there, but they aren't legal in many states (I live in one, NY).
John
Cam selection depends upon what you want to do with the car and how much money you have/how extreme you want to go. A car is a system. All the factors need to work together.
In a naturally asperated motor as the cams get 'hotter' there is a physical loss of compression due to overlap. To compensate you have to increase static compression. This will make the cams work. The cams also raise and narrow the powerband so you have to rev higher and change the gearing and shift more often.
In the late 1960's, Honda built some incedibly powerful Formula One engines. Their powerband was incrediby peaky and to make the powerband useful they had to have 17 speed gearboxes. The driver had to shift thousands of times per race.
Most people look at what is easiest to do first and cams are one of those things. Cams should be the last thing you do, if you do things in steps as you can afford them. If you can do it legally, the very first thing you should actually look at is a programable ECU to control what the motor is doing along with an EGT and a wideband AFR to monitor it. There are some very good ECU's out there, but they aren't legal in many states (I live in one, NY).
John
Re: (Racebrewer)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Racebrewer »</TD></TR><TR><TD CLASS="quote">Hi,
Cam selection depends upon what you want to do with the car and how much money you have/how extreme you want to go. A car is a system. All the factors need to work together.
In a naturally asperated motor as the cams get 'hotter' there is a physical loss of compression due to overlap. To compensate you have to increase static compression. This will make the cams work. The cams also raise and narrow the powerband so you have to rev higher and change the gearing and shift more often......John</TD></TR></TABLE>Hi John, when you said "increase static compression", what do you meant by that? Can you give us an example? Thanks.
-Chris-
Cam selection depends upon what you want to do with the car and how much money you have/how extreme you want to go. A car is a system. All the factors need to work together.
In a naturally asperated motor as the cams get 'hotter' there is a physical loss of compression due to overlap. To compensate you have to increase static compression. This will make the cams work. The cams also raise and narrow the powerband so you have to rev higher and change the gearing and shift more often......John</TD></TR></TABLE>Hi John, when you said "increase static compression", what do you meant by that? Can you give us an example? Thanks.
-Chris-
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