It seems that nearly every week someone on the forum asks about doing an H22 or H23 head swap onto their F22A block. Or an F22B1 head swap onto the F22A block as an upgrade. These and many other scenarios are questions that have been answered VERY thoroughly for way too many times. The reason is that people refuse to search and just assume that their idea is original or just don't care if the information is already out there. I want to make this page for the sole purpose of having a link to give you in response to these requests that will undoubtedly continue to pop up.
Do you actually have the ability to pull off a basic engine rebuild?
If not then you don't need to be dabbling in mating parts together that were not intended for each other. Start off with something more up to speed.
Do you really have a reason for doing this other than the fact that you can get a head for cheap/free or because you want a DOHC VTEC engine?
If that's the case, stop. You haven't thought about this. You're in shortcut mode because you think that the system can be beat for a couple hundred dollars. The few people who have had success with these combinations didn't do it because they wanted a cheap way out. Also, simply because an engine has the two properties of being DOHC and having VTEC doesn't create magic. Many more variables are against you here as will be discussed later.
Understand this thread:
http://www.cb7tuner.com/vbb/showthread.php?t=41915
All too often the hypothetical hybrid builds people think up or hear others doing can be disproved or invalidated by a simple dimensional figure. Most often this is trying to mate a block and head of different bore sizes. I made a crude image in MSPaint to show what's going on when you want to try putting a head for a larger bore engine on the block.
In the first example the image shows how the shape of the combustion chamber directs the air/gas mixture toward the top of the combustion chamber where the spark plug is. This is to create the most effective burn because more of the mixture CAN be burned.
In the second picture there appear to be two spots at the bottom of the combustion chamber. Since this is 2D I could only show it as a cutaway. That is actually a circular "pocket" of air that runs the circumference of the combustion chamber at the bottom. That space allows for turbulence to be created inside the combustion chamber instead of all of the mixture being directed toward the spark plug. The absence of material directly above the edge of the block deck also results in a more acute point. Inside a cylinder head that creates hot spots. Hot spots lead to detonation. Because this is a fairly large hot spot you run the risk of detonation causing engine failure.
Common frankenstein proposals:
H22A/H23A head onto an F22A/B block
The G22 as it's most often known. This example was the one illustrated in the MSPaint image. I showed why this one is far from ideal. A lot of people think this is the way to go because it's a cheaper alternative. You're just being lazy. Has it worked? Yes, it has. A few people have been able to do it. But that doesn't make it right. That doesn't mean they had a viable reason to defy the logic and do so. Their build is susceptible to all the issues I listed previously. Now if you wanted to sleeve your F22A to 87mm then bore differential is no longer an issue. Oil drains are a different matter. Another alternative would be a DOHC VTEC F20B head as it shares the same 85mm bore of the F22A/B blocks. However, it will still need two oil drain passages plugged on the head and the others don't line up well at all. Should you perform this swap, this is the compression ratio you'd end up with. Keep in mind, the factory F22A/B in the USA and Canada is already at a very low 8.8:1.
Assuming that is the case you'll need at minimum:
H22A head complete with cams, valves, springs and valve cover
H22A/H23A distributor
VTEC solenoid
H22A timing components
H22A water pump
H22A intake manifold
H22A header
H22A power steering pump and bracket if you want it
remove oil drain plug between cylinders 2 & 3
H22A injectors
H22A ECU(even then it's hardly correct)
These pictures are actually an F20B head and head gasket but they illustrate the requirements of blocking oil drains. The only difference in the heads is the combustion chamber diameter. The main thing you should get from these pictures really comes from the second one where you can imagine what the block deck surface of an F22A/B would be like up against the bottom of the head. You can see just how off the passages really are.
H22A head onto an F23A1 block
This is problematic for the same reason that the previous circumstance is, though because the 1mm larger bore, to a lesser extent. However, the oil passage concerns are still present. People like this one because of the longer 97mm stroke that the F23A1 crankshaft provides. It is a great stroke for making low end torque, and with some rod bolts and lighter pistons can rev just as capably as any other F-series with the exception of the F20B. The one saving grace behind this block is that it can be bored to match the 87mm needed to mate to an H22A head. But again, this does not solve the oil and coolant drain problems. They're still off just as badly as the picture I showed above.
F22B1 head onto an F22A block
This one's not recommended for a little different reason. Flow bench results have shown that the F22A head in stock form is a much better option than the F22B1/2/6 heads. A lot of people see VTEC on the F22B1 and think that it should offer them a substantial performance increase. This is just not the case. The head is horrible and the VTEC system used on SOHC heads is almost strictly for an economical benefit. The reasons not to do this head swap are the same as the reasons not to do an entire F22B1 swap also. Stick to the F22A and build it up. Have the exhaust ports gasket-matched and that will do WONDERS for that head.
F23A1/7 head onto an F22A block
This head is definitely an upgrade over the F22B1 head from a flow perspective. However, it's still not ideal and with some mild porting the F22A head will oust it. The VTEC on this head is not for performance either. And an issue that it shares with the H22/H23 head is that this head is designed for an 86mm bore. The difference is not as big as it would be with the H22/H23 head but it's still there. The only advantage I see in this head is the roller rocker assembly.
So now that we've covered that...
The bottom line is that these things continue to come up because they CAN be done. You will meet people who will tell you that they did them and that they worked just fine. I want to inform you that there are better (read:correct) ways of doing things. I do not disagree with mixing up parts. In fact, a build that I would like to do involves using parts from a few different Honda engines. But for head swaps there are many things that people simply don't consider. They're too consumed with getting "VTEC" or trying to have an "H22A" or DOHC without going through the process correctly. Be smart and use logic. Learn to build an engine that performs well over having something with a particular trait only good for showing off at meets.
One member on here who has put an H22A head onto an F22A block defends his stance by saying that he likes the torque produced over a standard H22A. If that's the case then there is a [COLOR="rgb(0, 255, 255)"]MUCH[/COLOR] better way to achieve this. Buy an H22A engine or longblock and proceed from there. Let's assume that there are a few givens, first.
Are all hybrids or Frankenstein combinations inherently bad?
NO!!!
-There is a no proper OBD1 ECU to run this combination so a custom map is required.
-A new headgasket will already be needed anyway if we agree the alternative was swapping the head out.
-Many additional parts besides the head itself will be needed.
If you desire to have the low-end torque of a 95mm+ crankshaft with the top-end power and aggressive cam profile that a DOHC VTEC head can provide then the JDM H23A VTEC from the Accord SiR wagon is your engine. However, sometimes H22As are cheaper to come by as they are more popular and more common. If you use your 95mm crankshaft and rods in the 50mm-main H22A block combined with USDM H22A1/4 pistons then you will achieve a static compression ratio just under 11.0:1. Of course with JDM H22A pistons this would be a little higher but that's not necessarily a bad thing if you have the ability to tune for it. The primary negative aspect to this build is that its pistons will protrude above the deck height by .020". Many have run this combination before and not had issues with it. Added insurance can be had by using an aftermarket .045" headgasket which would also drop compression to around 10.5:1 (with USDM pistons). A much better alternative would be to use the same combination with F20C1 pistons. They're shorter at 30mm tall and are compatible with FRM sleeves because that's what the F20C uses. You'll need to rebush any F/H-series rods for these as these are 23mm vs. the 22mm the other engines use. They're floating-pin also so if you had press-fit bushings you would need to rebush regardless.
Here are a couple of combinations that adopt from these suggestions:
My first suggestion, but not necessarily the best is the pre-'98 H22A block with a 95mm F22A/B or H23A1 crankshaft along with the 141.5mm rods and H22A pistons with an H22A head on top. Depending on whether USDM or JDM pistons are used your compression ratio will vary. Especially is you use a thicker gasket for additional clearance.
Here is another for the same combination but with F20C pistons used instead to avoid the negative-deck clearance issues. This is probably the most ideal and would respond very well to Type S cams and a decent header.
If you are only able to source a '98 and up H22A or H22A4 block then you are slightly more limited in your crankshaft options. Either you can find an H23A VTEC crankshaft which is dimensionally the same as the F22A/B and H23A1 but uses 55mm mains to conform to Honda's '98 and later convention or you can use the F23A1 crankshaft and rods for slightly more stroke. If the F23A1 crankshaft and rods are used along with the F20C pistons (again, wrist pin resizing is needed) then you'll end up with roughly these specs:
The benefits to building this combination from an existing H22A are:
-Correct bore sizing to combustion chamber diameter!!!!!!!!!!
-Oil and coolant passages that match perfectly.
-Having all the components listed previously in the minimum requirements list in one place.
-Oil squirters for the pistons!
-Additional displacement from the bore increase(relative to the F22A/B blocks).
F22A head onto an F23A block
Another combination that has been gaining popularity is the F23 bottom end swap. This typically uses the F23A1 bottom end with an F22A1 head. The SOHC VTEC heads that Honda made for the larger 4-cylinders have left a lot to be desired. True performance is generally easier to derive from the non-VTEC F22A heads instead. Camshaft options are also much better as well. This setup can really just be assembled and installed, but for the sake of being thorough, and because every single nit-pick was made about the other combinations, I've illustrated a way to perfect this combination below. For those who want to take it a step further, the F22B DOHC or F20A DOHC head can be used here as well. I believe PirateMcFred did it to a project of his but I don't remember build particulars. Deck height of the F23A block is still the same so you would need to treat the timing issue just like you would when swapping that head on an F22A block.
As we know the F23A1 cylinder bore is 86mm and the F22A combustion chamber is 85mm in diameter. This would seem to create the same ridge effect but in the opposite orientation. The reason that this isn't as dire as when the ridge is present on the cylinder is that the angle is obtuse and not acute. Heat can dissipate much easier. However, this is something that can be easily solved that can't be done to solve the cylinder ridge.
As before, I welcome criticism but I don't want angry responses or what your friend did. Just because things have been done doesn't make the reasoning behind them right at all. If you disagree, please present valid reasons why I'm wrong and why your method is better.
Do you actually have the ability to pull off a basic engine rebuild?
If not then you don't need to be dabbling in mating parts together that were not intended for each other. Start off with something more up to speed.
Do you really have a reason for doing this other than the fact that you can get a head for cheap/free or because you want a DOHC VTEC engine?
If that's the case, stop. You haven't thought about this. You're in shortcut mode because you think that the system can be beat for a couple hundred dollars. The few people who have had success with these combinations didn't do it because they wanted a cheap way out. Also, simply because an engine has the two properties of being DOHC and having VTEC doesn't create magic. Many more variables are against you here as will be discussed later.
Understand this thread:
http://www.cb7tuner.com/vbb/showthread.php?t=41915
All too often the hypothetical hybrid builds people think up or hear others doing can be disproved or invalidated by a simple dimensional figure. Most often this is trying to mate a block and head of different bore sizes. I made a crude image in MSPaint to show what's going on when you want to try putting a head for a larger bore engine on the block.
In the first example the image shows how the shape of the combustion chamber directs the air/gas mixture toward the top of the combustion chamber where the spark plug is. This is to create the most effective burn because more of the mixture CAN be burned.
In the second picture there appear to be two spots at the bottom of the combustion chamber. Since this is 2D I could only show it as a cutaway. That is actually a circular "pocket" of air that runs the circumference of the combustion chamber at the bottom. That space allows for turbulence to be created inside the combustion chamber instead of all of the mixture being directed toward the spark plug. The absence of material directly above the edge of the block deck also results in a more acute point. Inside a cylinder head that creates hot spots. Hot spots lead to detonation. Because this is a fairly large hot spot you run the risk of detonation causing engine failure.
Common frankenstein proposals:
H22A/H23A head onto an F22A/B block
The G22 as it's most often known. This example was the one illustrated in the MSPaint image. I showed why this one is far from ideal. A lot of people think this is the way to go because it's a cheaper alternative. You're just being lazy. Has it worked? Yes, it has. A few people have been able to do it. But that doesn't make it right. That doesn't mean they had a viable reason to defy the logic and do so. Their build is susceptible to all the issues I listed previously. Now if you wanted to sleeve your F22A to 87mm then bore differential is no longer an issue. Oil drains are a different matter. Another alternative would be a DOHC VTEC F20B head as it shares the same 85mm bore of the F22A/B blocks. However, it will still need two oil drain passages plugged on the head and the others don't line up well at all. Should you perform this swap, this is the compression ratio you'd end up with. Keep in mind, the factory F22A/B in the USA and Canada is already at a very low 8.8:1.
Assuming that is the case you'll need at minimum:
H22A head complete with cams, valves, springs and valve cover
H22A/H23A distributor
VTEC solenoid
H22A timing components
H22A water pump
H22A intake manifold
H22A header
H22A power steering pump and bracket if you want it
remove oil drain plug between cylinders 2 & 3
H22A injectors
H22A ECU(even then it's hardly correct)
These pictures are actually an F20B head and head gasket but they illustrate the requirements of blocking oil drains. The only difference in the heads is the combustion chamber diameter. The main thing you should get from these pictures really comes from the second one where you can imagine what the block deck surface of an F22A/B would be like up against the bottom of the head. You can see just how off the passages really are.
H22A head onto an F23A1 block
This is problematic for the same reason that the previous circumstance is, though because the 1mm larger bore, to a lesser extent. However, the oil passage concerns are still present. People like this one because of the longer 97mm stroke that the F23A1 crankshaft provides. It is a great stroke for making low end torque, and with some rod bolts and lighter pistons can rev just as capably as any other F-series with the exception of the F20B. The one saving grace behind this block is that it can be bored to match the 87mm needed to mate to an H22A head. But again, this does not solve the oil and coolant drain problems. They're still off just as badly as the picture I showed above.
F22B1 head onto an F22A block
This one's not recommended for a little different reason. Flow bench results have shown that the F22A head in stock form is a much better option than the F22B1/2/6 heads. A lot of people see VTEC on the F22B1 and think that it should offer them a substantial performance increase. This is just not the case. The head is horrible and the VTEC system used on SOHC heads is almost strictly for an economical benefit. The reasons not to do this head swap are the same as the reasons not to do an entire F22B1 swap also. Stick to the F22A and build it up. Have the exhaust ports gasket-matched and that will do WONDERS for that head.
F23A1/7 head onto an F22A block
This head is definitely an upgrade over the F22B1 head from a flow perspective. However, it's still not ideal and with some mild porting the F22A head will oust it. The VTEC on this head is not for performance either. And an issue that it shares with the H22/H23 head is that this head is designed for an 86mm bore. The difference is not as big as it would be with the H22/H23 head but it's still there. The only advantage I see in this head is the roller rocker assembly.
So now that we've covered that...
The bottom line is that these things continue to come up because they CAN be done. You will meet people who will tell you that they did them and that they worked just fine. I want to inform you that there are better (read:correct) ways of doing things. I do not disagree with mixing up parts. In fact, a build that I would like to do involves using parts from a few different Honda engines. But for head swaps there are many things that people simply don't consider. They're too consumed with getting "VTEC" or trying to have an "H22A" or DOHC without going through the process correctly. Be smart and use logic. Learn to build an engine that performs well over having something with a particular trait only good for showing off at meets.
One member on here who has put an H22A head onto an F22A block defends his stance by saying that he likes the torque produced over a standard H22A. If that's the case then there is a [COLOR="rgb(0, 255, 255)"]MUCH[/COLOR] better way to achieve this. Buy an H22A engine or longblock and proceed from there. Let's assume that there are a few givens, first.
Are all hybrids or Frankenstein combinations inherently bad?
NO!!!
-There is a no proper OBD1 ECU to run this combination so a custom map is required.
-A new headgasket will already be needed anyway if we agree the alternative was swapping the head out.
-Many additional parts besides the head itself will be needed.
If you desire to have the low-end torque of a 95mm+ crankshaft with the top-end power and aggressive cam profile that a DOHC VTEC head can provide then the JDM H23A VTEC from the Accord SiR wagon is your engine. However, sometimes H22As are cheaper to come by as they are more popular and more common. If you use your 95mm crankshaft and rods in the 50mm-main H22A block combined with USDM H22A1/4 pistons then you will achieve a static compression ratio just under 11.0:1. Of course with JDM H22A pistons this would be a little higher but that's not necessarily a bad thing if you have the ability to tune for it. The primary negative aspect to this build is that its pistons will protrude above the deck height by .020". Many have run this combination before and not had issues with it. Added insurance can be had by using an aftermarket .045" headgasket which would also drop compression to around 10.5:1 (with USDM pistons). A much better alternative would be to use the same combination with F20C1 pistons. They're shorter at 30mm tall and are compatible with FRM sleeves because that's what the F20C uses. You'll need to rebush any F/H-series rods for these as these are 23mm vs. the 22mm the other engines use. They're floating-pin also so if you had press-fit bushings you would need to rebush regardless.
Here are a couple of combinations that adopt from these suggestions:
My first suggestion, but not necessarily the best is the pre-'98 H22A block with a 95mm F22A/B or H23A1 crankshaft along with the 141.5mm rods and H22A pistons with an H22A head on top. Depending on whether USDM or JDM pistons are used your compression ratio will vary. Especially is you use a thicker gasket for additional clearance.
Here is another for the same combination but with F20C pistons used instead to avoid the negative-deck clearance issues. This is probably the most ideal and would respond very well to Type S cams and a decent header.
If you are only able to source a '98 and up H22A or H22A4 block then you are slightly more limited in your crankshaft options. Either you can find an H23A VTEC crankshaft which is dimensionally the same as the F22A/B and H23A1 but uses 55mm mains to conform to Honda's '98 and later convention or you can use the F23A1 crankshaft and rods for slightly more stroke. If the F23A1 crankshaft and rods are used along with the F20C pistons (again, wrist pin resizing is needed) then you'll end up with roughly these specs:
The benefits to building this combination from an existing H22A are:
-Correct bore sizing to combustion chamber diameter!!!!!!!!!!
-Oil and coolant passages that match perfectly.
-Having all the components listed previously in the minimum requirements list in one place.
-Oil squirters for the pistons!
-Additional displacement from the bore increase(relative to the F22A/B blocks).
F22A head onto an F23A block
Another combination that has been gaining popularity is the F23 bottom end swap. This typically uses the F23A1 bottom end with an F22A1 head. The SOHC VTEC heads that Honda made for the larger 4-cylinders have left a lot to be desired. True performance is generally easier to derive from the non-VTEC F22A heads instead. Camshaft options are also much better as well. This setup can really just be assembled and installed, but for the sake of being thorough, and because every single nit-pick was made about the other combinations, I've illustrated a way to perfect this combination below. For those who want to take it a step further, the F22B DOHC or F20A DOHC head can be used here as well. I believe PirateMcFred did it to a project of his but I don't remember build particulars. Deck height of the F23A block is still the same so you would need to treat the timing issue just like you would when swapping that head on an F22A block.
As we know the F23A1 cylinder bore is 86mm and the F22A combustion chamber is 85mm in diameter. This would seem to create the same ridge effect but in the opposite orientation. The reason that this isn't as dire as when the ridge is present on the cylinder is that the angle is obtuse and not acute. Heat can dissipate much easier. However, this is something that can be easily solved that can't be done to solve the cylinder ridge.
As before, I welcome criticism but I don't want angry responses or what your friend did. Just because things have been done doesn't make the reasoning behind them right at all. If you disagree, please present valid reasons why I'm wrong and why your method is better.
Comment