I would really like to find someone also the turbos a 2 stroke... I know I emailed kms about this and they said they are a 4 stroke shop.... I found someone on ut. .. but have heard mixed reviews on the shop...
KTM 450 SXF KMS Turbo Build start to finish
- Thread starter KMS
- Start date
M
I talked to kelly and sounds like next season turbo smokers will be available. I'm leaning this way!
K
Piston is here! Just walked in today and I must say after inspection she's a beauty. We had JE custom make this for us (no one makes a 10:1 piston for a 102mm bore KTM 450). Compared to stock (picture below) this thing definitely means business.
When making a turbo piston (especially for a big bore), care must be observed to weight. You want a strong piston where it counts, not just a lot of aluminum. Why? A heavy piston will tear a motor up. Every time a piston changes direction it thrusts into the cylinder. Heavy pistons will have shorter life expectancy by literally wearing out the clearances between piston and cylinder. Furthermore, they will reek havoc on crank bearings because the crank/rod/piston system is now out of balance.
So how can you make such a large turbo piston and keep the weight close to a stock piston? Here is how:
Smart reinforcing forging where the stresses are highest and...
Under-dome milling. They cut the underside of the piston to contour with the crown and valve reliefs removing excess material and ensuring a uniform dome thickness. This machining process is a must have when you are going this big and is worth every penny. Here is why:
Stock piston:
New KMS 102mm Turbo piston:
The new piston only weighs 20 grams more than a stock one. That is only a 7.5% change in weight with a +7mm bore piston. Keeping this monster on a diet not only ensures a motor that can lay down the big power, but also last year after year.
Wow that piston is a piece of work, I imagine they had quite a bit of time into that.
K
KTM 450 Head is here. We had this head cnc cut specifically for this bore and turbo combo.
The port work is generated in a computer model, cut in a cnc machine and finished by hand (to smooth out machine marks). Then the head is dropped in cnc seat cutter that not only provides a very precise finish, but also deshrouds the valve area. This is a huge help to head flow when considering combustion chamber shape.
Here is a feature that makes this head very specific to the bore. Notice the stock head gasket is in the valve pocket now...
Since we are using a 102mm bore we wanted the very most head flow in the combustion chamber as possible. Here is a pic with 102mm head gasket.
M
Now that's a PISTON!
K
Our cylinder has come back as well. We special cut all our big bore cylinders (even our naturally aspirated ones) to reinforce the head gasket fire ring area.
What we do, is raise the fire ring section of the cylinder by .003". Why? Focused Pressure. When you torque down a part, the hardware applies a radial pressure area. The pressure around the bolt (or stud) is really high, yet as you move away from the hardware the pressure actually drops. When talking head gaskets, the most stressed area is the fire ring (the area that surrounds the bore). We want the highest clamping force possible on the fire ring area, so we give the parts no choice and raise this section...and it works great. Here is a closer view:
It is a very economical process and can be used with any MLS (multi layered steel) gasket, like a Cometic. So... you take a set of these, use a standard gasket, and go have some big power fun because that head gasket is ready for battle.
Here is all the top end parts together:
Next...install. We were going from the install straight to the turbo setup, however I have had many requests to see what this will do all by itself. So that is what we are going to do...We are going to make some dyno pulls and then go turbo.
What we do, is raise the fire ring section of the cylinder by .003". Why? Focused Pressure. When you torque down a part, the hardware applies a radial pressure area. The pressure around the bolt (or stud) is really high, yet as you move away from the hardware the pressure actually drops. When talking head gaskets, the most stressed area is the fire ring (the area that surrounds the bore). We want the highest clamping force possible on the fire ring area, so we give the parts no choice and raise this section...and it works great. Here is a closer view:
It is a very economical process and can be used with any MLS (multi layered steel) gasket, like a Cometic. So... you take a set of these, use a standard gasket, and go have some big power fun because that head gasket is ready for battle.
Here is all the top end parts together:
Next...install. We were going from the install straight to the turbo setup, however I have had many requests to see what this will do all by itself. So that is what we are going to do...We are going to make some dyno pulls and then go turbo.
J
Very cool!
Thanks for taking the time to share
Thanks for taking the time to share
Very impressive write up! And two thumbs up for the attention to detail! I would love to have you build me a turbo for my Ktm 300sx set-up! Maybe next year huh?? I will start saving my pennies!
K
Thanks for the "thanks". It does take much time to pull stuff like this together, however I feel it is really important to share the knowledge.
On the topic of time, I do want to apologize for this week's Turbo Talk. Part 2 of the Clutch will be postponed until next Friday. I had to prioritize deadlines for my customers, so I'm sorry for the delay.
Thanks
On the topic of time, I do want to apologize for this week's Turbo Talk. Part 2 of the Clutch will be postponed until next Friday. I had to prioritize deadlines for my customers, so I'm sorry for the delay.
Thanks
C
Build
The JE piston is 2618 alloy versus the 4032 high silicone temp stable Oem piston.
15% difference in expansion rates.
The JE piston is 2618 alloy versus the 4032 high silicone temp stable Oem piston.
15% difference in expansion rates.
Last edited:
Similar threads
