New K2H crank for H-series engine
01-19-2014, 12:54 PM
#1
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New K2H crank for H-series engine
Here is some information that is for the new K2H crankshaft made by Roskoracing.com
Rosko K24 Crank
I’ve been asked many times over the years if I offer a “kit” to install the Honda/Acura K24 99mm stroke crankshaft in an H series block. I have been running the K24 crankshaft for the past several seasons in my H series block with great success, but until now I have not offered the setup to customers. Though it is not as cut and dry as installing the H23 crank, it can be done and is a great alternative to more expensive aftermarket crankshafts.
Does the crank drop right into my H series block?
Yes, kind of. The basic dimensions of the crank allow it to physically drop into a 55mm H series block. The main journals are 55mm, the bore spacing is the same, and the flywheel bolt pattern and main seal diameter are also the same. The big difference is that the K24 engine uses a chain instead of a timing belt, and does not share the same oil pump drive as the H motor does. The crankshaft snout, because of those differences, is also about an inch shorter.
How do you drive the oil pump?
When I modify the cranks, the first thing I do is remove the step of material from the snout next to the #1 main journal. Once this is removed a sleeve can be made to mimic the H series oil pump drive. The sleeve is made from heat treated tool steel and is pressed over the snout of the crankshaft. The combination of the interference fit and Loctite flange sealant will keep oil inside the crankcase where it belongs. The drive lugs on the pressed on sleeve will turn the oil pump just as an H crank would.
What about the length of the snout?
The snout of the K24 crank is about an inch shorter than an H series. The problem here is that when you slip the timing gear on, it already hangs off the end of the crankshaft and there is nothing left to install the crank pulley onto. This is where I do things a bit differently. Where others have tried to extend the crank by welding, or making some sort of spacer, I chose a totally different route. Rather than risk the structural integrity of the crankshaft by welding on it, I manufactured a custom timing belt gear that doubles as a hub for an ATI race dampener to mount to. Doing so the crankshaft does NOT need to be extended and a reliable setup is achieved.
If the crank timing gear and hub are one piece, how hard is it to install the timing belt?
The crank timing gear/hub and dampener need to go on with the belt at the same time. This isn’t really any harder to do, its just different than you may be used to. Simply slide the timing belt over the crank timing gear, and then slide the crank gear/hub assembly onto the crankshaft snout together. Once it is on, install the timing belt around the gears like normal. Tip: It helps to only install the gear/hub partially onto the crank snout, until the timing belt is fully installed, then seat the timing gear/hub assembly against the oil pump. Of course, the KS timing tensioner makes this a breeze.
What about the timing cover?
Unfortunately the timing cover will need to be modified as it would now need to go around the ATI race pulley. You will need to cut out a diameter from your timing cover and fit it over top of the ATI crank pulley. You can also choose to eliminate the timing cover but do so at your own risk.
Will the ATI dampener run my alternator?
The ATI race dampeners do not have an alternator pulley from the factory, however one can still be installed. The ATI dampeners were designed to use a BBC (Big Block Chevy) as an accessory that bolts to the face of the dampener. These pullies are readily available if needed.
What about my alternator mount, will it line up?
Chances are it will not. Due to the custom nature of this project and the desire to retain as much clearance as possible between the motor and frame rail, there is a very good chance you will need to modify or custom make an alternator bracket. Our main focus was to keep the hub and dampener as tight to the motor as possible for balance and clearance reasons. We will however be working on a solution to this as well, most likely in the form of a D series alternator and custom mount.
Can an H series clutch and flywheel be used?
Absolutely. There is one small modification we do to the flywheel end of the crankshaft. A K24 crank has a small boss in the center of that mating surface that a K series flywheel locates on. The H series flywheels do not use this so this feature is machined off. Once that boss is gone the flywheel end of the crankshaft becomes identical to the H series. Same diameter, same bolt pattern, same locating pin etc. The same H clutch you had before can still be used.
What rods and pistons do I use?
Unfortunately there is not a “good” off the shelf solution for this, but there are some. The easy way is to use a K20 rod along with an H series piston. Doing so will net you a horrible R/S (rod to stroke) ratio however and the more favorable solution is to use both a custom length rod and piston. Remember this is a K series crank so you will want to spec out the narrower K series journal width rather than the H series width. For a piston design all dimensions would be H series, only with a shorter compression height to accommodate the length of rod you choose. I recommend going with the shortest compression height you feel comfortable with and making the rest up with a longer rod length for the best R/S ratio possible.
How many CC’s will this make my motor?
87mm bore size X 99mm stroke = 2354 cc’s
88mm bore size X 99mm stroke = 2408 cc’s
89mm bore size X 99mm stroke = 2463 cc’s
90mm bore size X 99mm stroke = 2519 cc’s
Rosko K24 Crank
I’ve been asked many times over the years if I offer a “kit” to install the Honda/Acura K24 99mm stroke crankshaft in an H series block. I have been running the K24 crankshaft for the past several seasons in my H series block with great success, but until now I have not offered the setup to customers. Though it is not as cut and dry as installing the H23 crank, it can be done and is a great alternative to more expensive aftermarket crankshafts.
Does the crank drop right into my H series block?
Yes, kind of. The basic dimensions of the crank allow it to physically drop into a 55mm H series block. The main journals are 55mm, the bore spacing is the same, and the flywheel bolt pattern and main seal diameter are also the same. The big difference is that the K24 engine uses a chain instead of a timing belt, and does not share the same oil pump drive as the H motor does. The crankshaft snout, because of those differences, is also about an inch shorter.
How do you drive the oil pump?
When I modify the cranks, the first thing I do is remove the step of material from the snout next to the #1 main journal. Once this is removed a sleeve can be made to mimic the H series oil pump drive. The sleeve is made from heat treated tool steel and is pressed over the snout of the crankshaft. The combination of the interference fit and Loctite flange sealant will keep oil inside the crankcase where it belongs. The drive lugs on the pressed on sleeve will turn the oil pump just as an H crank would.
What about the length of the snout?
The snout of the K24 crank is about an inch shorter than an H series. The problem here is that when you slip the timing gear on, it already hangs off the end of the crankshaft and there is nothing left to install the crank pulley onto. This is where I do things a bit differently. Where others have tried to extend the crank by welding, or making some sort of spacer, I chose a totally different route. Rather than risk the structural integrity of the crankshaft by welding on it, I manufactured a custom timing belt gear that doubles as a hub for an ATI race dampener to mount to. Doing so the crankshaft does NOT need to be extended and a reliable setup is achieved.
If the crank timing gear and hub are one piece, how hard is it to install the timing belt?
The crank timing gear/hub and dampener need to go on with the belt at the same time. This isn’t really any harder to do, its just different than you may be used to. Simply slide the timing belt over the crank timing gear, and then slide the crank gear/hub assembly onto the crankshaft snout together. Once it is on, install the timing belt around the gears like normal. Tip: It helps to only install the gear/hub partially onto the crank snout, until the timing belt is fully installed, then seat the timing gear/hub assembly against the oil pump. Of course, the KS timing tensioner makes this a breeze.
What about the timing cover?
Unfortunately the timing cover will need to be modified as it would now need to go around the ATI race pulley. You will need to cut out a diameter from your timing cover and fit it over top of the ATI crank pulley. You can also choose to eliminate the timing cover but do so at your own risk.
Will the ATI dampener run my alternator?
The ATI race dampeners do not have an alternator pulley from the factory, however one can still be installed. The ATI dampeners were designed to use a BBC (Big Block Chevy) as an accessory that bolts to the face of the dampener. These pullies are readily available if needed.
What about my alternator mount, will it line up?
Chances are it will not. Due to the custom nature of this project and the desire to retain as much clearance as possible between the motor and frame rail, there is a very good chance you will need to modify or custom make an alternator bracket. Our main focus was to keep the hub and dampener as tight to the motor as possible for balance and clearance reasons. We will however be working on a solution to this as well, most likely in the form of a D series alternator and custom mount.
Can an H series clutch and flywheel be used?
Absolutely. There is one small modification we do to the flywheel end of the crankshaft. A K24 crank has a small boss in the center of that mating surface that a K series flywheel locates on. The H series flywheels do not use this so this feature is machined off. Once that boss is gone the flywheel end of the crankshaft becomes identical to the H series. Same diameter, same bolt pattern, same locating pin etc. The same H clutch you had before can still be used.
What rods and pistons do I use?
Unfortunately there is not a “good” off the shelf solution for this, but there are some. The easy way is to use a K20 rod along with an H series piston. Doing so will net you a horrible R/S (rod to stroke) ratio however and the more favorable solution is to use both a custom length rod and piston. Remember this is a K series crank so you will want to spec out the narrower K series journal width rather than the H series width. For a piston design all dimensions would be H series, only with a shorter compression height to accommodate the length of rod you choose. I recommend going with the shortest compression height you feel comfortable with and making the rest up with a longer rod length for the best R/S ratio possible.
How many CC’s will this make my motor?
87mm bore size X 99mm stroke = 2354 cc’s
88mm bore size X 99mm stroke = 2408 cc’s
89mm bore size X 99mm stroke = 2463 cc’s
90mm bore size X 99mm stroke = 2519 cc’s
01-19-2014, 02:38 PM
#2
Re: New K2H crank for H-series engine
That is so very trick! Bravo. Just when some say that there is nothing new in this. I would love to turn my H into a 2.4l.
What does the crank and adapter go for?
What does the crank and adapter go for?
01-19-2014, 03:49 PM
#6
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Re: New K2H crank for H-series engine
01-19-2014, 09:31 PM
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Re: New K2H crank for H-series engine
Thanks for posting info on the k24 crank setup. I have been waiting a couple years for some good info. I like the oil pump drive gear idea. Looks very reliable. Can i buy just the oil pump gear? I have been toying with this setup for awhile and that is the only piece I have been stuck on. I was able to make everything else on my lathe.
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01-22-2014, 07:31 AM
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