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There are some similarities with the F20C and K20A motors. They spin the same way, they have the same bore spacing, and other similarities. There is a lot of speculation on how the two engines might be melded together to get the F20C's 240hp performance with the FWD 6spd transmission of the K20A.

As you may or may not know, I am in charge of product developement for Hasport and looked into this about a year ago, so let me share some information.

Can you bolt an F20C head on a K20 block?
For all practical pruposes, no. The F20C head will probably bolt on, although I've not tried, but the problem is with the cams and cam gears. If you look at the image below you will see that the cam chain goes over a seperate sprocket rather than the cam gears as it does on the K-motor. If you look at the sprocket (7) you'll see that it drives a helical gear (11), the gear in turn drives the cam gears. That means the cams rotate opposite to the direction of the crankshaft.

So if you wished to use the F20C head some custom fabrication would need to be done. Besides the obvious cam issue other problems might include the mating surfaces for the cam chain cover, coolant ports, or oil passages including the VTEC oil port.

(Image edited: I'll download the image and get it here)

I'm not saying it's impossible, just impractical. In the mid 90s there were several companies that were machining H22 (F22B?) heads for Super Touring Accords so that they could mount them backwards on the block. Their budget was a bit larger than the average Honda clown.

Can you bolt the F20C engine to the K20A 6 speed transmission?
You could make an adapter plate and custom flywheel to make this relatively easy to do. Also a year ago, Prototype Engineering made a bell housing to use with the K-motor 6spd so that it could be bolted straight to the engine with no adapter or custom flywheel. I'm sure if either one of these solutions went into production they could be had for under $1000 bucks.


Once you do this however, there's another problem. The mounts are on each side of the engine with no provision for mounting one on the timing chain end or nose of the motor. Of course you can custom fabricate these that's no big deal. Special car will need to be taken so that the engine doesn't twist under hard exceleration. A mount on the nose of the engine helps here because having your main mounting points close to in line with the longitudinal axis of the engine keeps axles problems and vibration to a minimum.

With people getting 240+ wheel hp out of K20A's with relatively minor modification I believe the performance is'nt that great to warranty the expense. But that is simply my opinion.

How about the crankshaft from the S2000?
There is some potential there. Right now as many of you may already know people are looking to destroke the K24 to take advantage of the taller deck but improve on the mediocre K24 rod/stroke ratio. Not just the F22C cranks are being used, people are also using the crank from the H22 and H23. A free revving K22 or K23 would be a force to be reconned with.

How about the pistons and rods from the S2000?
Again. there is some potential. Many people are working on sorting out these combinations and we will see some cars on the road shortly with these parts.

What else is being used?
I've heard that some of the other parts being used are the valves which are 1mm larger and valve springs. Since these components are designed for a Honda engine that revved to 9K it is tough to go wrong here.

As for other F20/22 engine parts, I think the biggie that is being overlooked is possibly using the S2000 intake manifold. The K20 intake manifold is a bit of a compromise design for packaging demands. It leaves a lot to be desired. The S2000 engine bay had a lot more room to work with as well as simple fact that it fed a more powerful engine. I want someone to adapt one to a K20. Of course it won't work in an RSX or Si without some work on the front of the car. The radiator sits in the way.

I hope you guys find this information useful.

brian g
 

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Yea great info!
good thing i'm not doing any thing motor wise, to my car for atleast a year....by the time i'm ready there will be sum really cool shit to do w/ these K series motors!
 

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Awesome read and info Brian, thanks for taking the time to write something like this..I feel smarter already!!! :D
 

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h23 crank in k24

I was just curious...does any modification have to be done to fit the 95mm crank from a h23 into a k24? I was thinking more about the bearing sizes and the switch from belt to chain...does anything have to be modified?
 

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I was told that using the F22 crank in the K24 might lead to reliability issues. Do you have any comment on that?
 

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Discussion Starter #7
22crazy said:
I was just curious...does any modification have to be done to fit the 95mm crank from a h23 into a k24? I was thinking more about the bearing sizes and the switch from belt to chain...does anything have to be modified?
Yes, modifications have to be done. But other than resizing the nose of the crank I haven't paid enough attention to the discussions to tell you what they might be.


jon v said:
I was told that using the F22 crank in the K24 might lead to reliability issues. Do you have any comment on that?
The two sides to that story are, revving a K24 above 8k rpm will lead to reliability issues. Anytime you push the engine beyond it's design specifications it leads to a decrease in reliability. Whoever you where talking to is merely stating the obvious.

The issue here is how to make more power with the parts that are available. When using the F22 crank your making some compromises to achieve certain goals. You have to weigh the pluses and minuses.

Your taking a shorter stroke crank that was designed by Honda to rev above 8K and coupling it with the K24 bottom end. The crank will have to be modified which may lead to less reliability depending on how it's done. But you are going to get a better rod stroke ratio, which will have reliability benefits. The eventual goal is more power, which always comes at the expense durability. You can minimize the durability issues though and that is what using the F22 crank is about.

brian g
 

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What modifications will need to be done to the F22 crank in order to fit? Ive read that they drop right in and now im reading that they don't. Which one is it? Thx
 

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Discussion Starter #9
92si said:
What modifications will need to be done to the F22 crank in order to fit? Ive read that they drop right in and now im reading that they don't. Which one is it? Thx
The nose has to be machined.

brian g
 

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brian g said:
92si said:
What modifications will need to be done to the F22 crank in order to fit? Ive read that they drop right in and now im reading that they don't. Which one is it? Thx
The nose has to be machined.

brian g
would you happen to know by how much?

and let me get this straight...if you use the f22c crank in the k24..then what kind of rods/ pistons will need to be used?

Thanks
 

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Discussion Starter #11
10seceg said:
would you happen to know by how much?
Nope

10seceg said:
and let me get this straight...if you use the f22c crank in the k24..then what kind of rods/ pistons will need to be used?
Not sure, If I were trying to do this I would measure the deck height of the K24 and compare it to the F22C and see if these were possible to use.

brian g
 

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nice write up ...some good info on this thread ...exactly what i was looking for ... :up: :up:
 

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keep it coming brian, i'm soking it all up

ps: if any one has a f22c crank that they would be willing to sell me just pm me..
 

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o'h hay brian do you know if the crank pullys are interchangeable. i would like to get a harmonic dampener/fluid dampener bit i doubt any one's makes them for the k series yet, but the f series has been arround long enough i'm shure.
 
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