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K (as in: que?) Ja (as in: Ja ba the Hut) busa (as in: insane crotch rocket)
Well I figure it is time to let one of the secrets out of the bag. Those who like to fabricate or experiment will like this one. For quite some time I have been searching vigorously for a lightweight racing piston possibilty or even a maker that could make them for a reasonable price because the ultimately lightweight racing pistons such as the ones found in F1 race cars and the like are far beyond most of our pocketbooks.
So I have finally found something that looks to be very promising but it also has it's limitations. My find involves OEM (standard 81mm) Hayabusa Pistons. I wanted to wait for a bit to release this info so that I could get enough pistons to experiment with and at a reasonable price so that if it doesn't work then I won't have a lot invested into this experiment.
Below is the current investment I have in this project (not including my time) and I will update this as the project progresses:
1) Complete KJ engine costs under $200 but "S" rods sell for that -SC sells for $200 more-or-less and injectors go for $100 more-or-less so cost is free or better than free depending upon sales of un-needed pieces.
2) KJ crank -then can also be considered free but requires a custom pulley arrangement so that makes a later cost
3) 1st gen Busa piston/rod combos can be bought for as little as $40 for the set. Rods can be sold later for $40 or more per set.
1. Block = 00.00
2. Pistons = 00.00
3. Crank = 00.00
3. Bore Block = 90.00
4. Hone Rods = 30.00
TOTAL
(Thus far) = 120.00
Here are a few photos of the Hayabusa's and you will soon see why they are a good K-engine experiment:
Busa piston pins are the same .787 diameter as the standard KL pins. This means they can be mounted on KL rods but the rods must be drilled for oil and honed for full floating wrist pin. Due to the unique shape of the piston on the sides -there is no adequate backing surface to press pins (as found from experimentation later in this thread). KL rods are not extreme horsepower brutes as well known. But they are lightweight compared to some of the more heavy duty upgrades. And they are definitely more lightweight towards the smaller end. This means a much increased mean piston speed (MPS) which equates to a much higher RPM potential.
So here are a few weights for comparison:
Pistons:
KLDE = 252
Hayabusa OEM = 217 grams
Mahle Hayabusa = 245 grams
KLDE -Ross Forged = 330 grams
Pins:
KLDE = 88 grams
Hayabusa OEM = 67 grams
Mahle = 82.7 grams
KLDE -Ross = 116 grams
Another very nice bit of info on the Busa pistons is that they are factory forged pieces. Yes -that is right! FORGED!
OK so one of the limitations is that there is only one piston size that will work for any K series engine and that is the 81mm stock Busa piston with the KJ block. The 81mm Busa piston would require boring the KJ block about .020 over. That is just about as perfect of a jumbalaya as you can get.
Here are a few photos of the 81mm Busa compared to a OEM stock bore KJ piston:
Now the KJ block is not easy to work with. Although it does have the fancy piston oil squirters that the KL lacks. But to modify the KJ to work as a normal KL does then a few changes need to be made. It does not have many of the same bolt provisions on the front end that the KL has. And the water pump is different.
The valley needs some modifications because it is divided into three sections. The two end sections are for oil return from the "S" supercharger and the center section has the standard knock sensor and a oil feed port (exact piece as head oil restricters) for the supercharger oil supply. Photos below:
The Busa piston deck height is .17 shorter than the standard KL piston. So this means that the piston to head distance (with this combo) must be reduced by approximately this amount to make the compression ratio in a usable range.
A KLDE or KLZE crank will fit in a KJ block. The KJ crank cannot be used unless you machine the nose of it to the same as the DE because it has a taper fit for the "S" harmonic balancer. But other than the tapered nose -they are nearly identical.
So to make the .17 - my idea is to deck the block by some and then deck the heads to make up the rest. I have verified how much can be taken off the deck by measuring the lip thickness at the top of the cylinder liners and they are approximately .145 thick before they begin to taper inward. Reference photo: http://www.xtremethings.com/Engineer...LDE_Sleeve.jpg
So another limitation of this experiment is that if you remove some from the deck then you must either use adjustable camshaft gears or re-pin and re-mark your stock OEM gears in an alternate location so that the belt will allow the cams to line up in the correct degrees at TDC.
I hope a few people enjoy this thread and I will post pics and info as the experiment progresses.
P.S. Before someone asks -A K8 block will not work with any size of Hayabusa piston. The difference between the bores is too far out of range. I did a lot of number crunching to check and it just isn't possible. And also before someone asks -81mm is the only size that will work for this combo. And 82mm aftermarket Busa piston is more than .040 overbore in the KJ and even the largest Busa overbore piston you can get (84mm) is just a bit shy of working in a KL block. So again -much limitation!
Well I figure it is time to let one of the secrets out of the bag. Those who like to fabricate or experiment will like this one. For quite some time I have been searching vigorously for a lightweight racing piston possibilty or even a maker that could make them for a reasonable price because the ultimately lightweight racing pistons such as the ones found in F1 race cars and the like are far beyond most of our pocketbooks.
So I have finally found something that looks to be very promising but it also has it's limitations. My find involves OEM (standard 81mm) Hayabusa Pistons. I wanted to wait for a bit to release this info so that I could get enough pistons to experiment with and at a reasonable price so that if it doesn't work then I won't have a lot invested into this experiment.
Below is the current investment I have in this project (not including my time) and I will update this as the project progresses:
1) Complete KJ engine costs under $200 but "S" rods sell for that -SC sells for $200 more-or-less and injectors go for $100 more-or-less so cost is free or better than free depending upon sales of un-needed pieces.
2) KJ crank -then can also be considered free but requires a custom pulley arrangement so that makes a later cost
3) 1st gen Busa piston/rod combos can be bought for as little as $40 for the set. Rods can be sold later for $40 or more per set.
1. Block = 00.00
2. Pistons = 00.00
3. Crank = 00.00
3. Bore Block = 90.00
4. Hone Rods = 30.00
TOTAL
(Thus far) = 120.00
Here are a few photos of the Hayabusa's and you will soon see why they are a good K-engine experiment:
Busa piston pins are the same .787 diameter as the standard KL pins. This means they can be mounted on KL rods but the rods must be drilled for oil and honed for full floating wrist pin. Due to the unique shape of the piston on the sides -there is no adequate backing surface to press pins (as found from experimentation later in this thread). KL rods are not extreme horsepower brutes as well known. But they are lightweight compared to some of the more heavy duty upgrades. And they are definitely more lightweight towards the smaller end. This means a much increased mean piston speed (MPS) which equates to a much higher RPM potential.
So here are a few weights for comparison:
Pistons:
KLDE = 252
Hayabusa OEM = 217 grams
Mahle Hayabusa = 245 grams
KLDE -Ross Forged = 330 grams
Pins:
KLDE = 88 grams
Hayabusa OEM = 67 grams
Mahle = 82.7 grams
KLDE -Ross = 116 grams
Another very nice bit of info on the Busa pistons is that they are factory forged pieces. Yes -that is right! FORGED!
OK so one of the limitations is that there is only one piston size that will work for any K series engine and that is the 81mm stock Busa piston with the KJ block. The 81mm Busa piston would require boring the KJ block about .020 over. That is just about as perfect of a jumbalaya as you can get.
Here are a few photos of the 81mm Busa compared to a OEM stock bore KJ piston:
Now the KJ block is not easy to work with. Although it does have the fancy piston oil squirters that the KL lacks. But to modify the KJ to work as a normal KL does then a few changes need to be made. It does not have many of the same bolt provisions on the front end that the KL has. And the water pump is different.
The valley needs some modifications because it is divided into three sections. The two end sections are for oil return from the "S" supercharger and the center section has the standard knock sensor and a oil feed port (exact piece as head oil restricters) for the supercharger oil supply. Photos below:
The Busa piston deck height is .17 shorter than the standard KL piston. So this means that the piston to head distance (with this combo) must be reduced by approximately this amount to make the compression ratio in a usable range.
A KLDE or KLZE crank will fit in a KJ block. The KJ crank cannot be used unless you machine the nose of it to the same as the DE because it has a taper fit for the "S" harmonic balancer. But other than the tapered nose -they are nearly identical.
So to make the .17 - my idea is to deck the block by some and then deck the heads to make up the rest. I have verified how much can be taken off the deck by measuring the lip thickness at the top of the cylinder liners and they are approximately .145 thick before they begin to taper inward. Reference photo: http://www.xtremethings.com/Engineer...LDE_Sleeve.jpg
So another limitation of this experiment is that if you remove some from the deck then you must either use adjustable camshaft gears or re-pin and re-mark your stock OEM gears in an alternate location so that the belt will allow the cams to line up in the correct degrees at TDC.
I hope a few people enjoy this thread and I will post pics and info as the experiment progresses.
P.S. Before someone asks -A K8 block will not work with any size of Hayabusa piston. The difference between the bores is too far out of range. I did a lot of number crunching to check and it just isn't possible. And also before someone asks -81mm is the only size that will work for this combo. And 82mm aftermarket Busa piston is more than .040 overbore in the KJ and even the largest Busa overbore piston you can get (84mm) is just a bit shy of working in a KL block. So again -much limitation!
OBJECTS IN THE MIRROR ARE LOSING
in its prime
1993 PGT-DE-T Silver Surfer - 8psi
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