440 Kawasaki PSRU design, parts, plans, sources

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Armilite

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Watercooled, 4 sparkplug, 1 piece head narrows it down to a 1981 or 1982 engine used in the Kawasaki LTD snowmobile. (2 years only)

Fairly high strung motor - 76hp @8200 rpm Using dual tuned exhausts.
It's claim to fame was the fact it had 8 transfer ports to move a lot of Air required for that [email protected] high RPMs
For aviation use the Dyno graph shows around 45-50 hp in the 6000-6500 rpm range.

The Shop manual for your engine has about anything you need to keep it running.

If it still has the original Keihn Butterfly carbs they are very different as far how they are tuned/jetted etc. compared to Bing or Mikuni slide carbs. The shop book has the info on what to do.

BTW - from what I can tell it has a fairly high compression ratio - 12:1
Even though the manual says minimum 89 octane I'd run good 93 pump gas or better.
View attachment 118652View attachment 118653
============================

Yes, [email protected] Thats a nice manual! Good find! That's WHY you wouldn't want to use this Sled Pipe Designed for 8200rpm on any Plane. (68mm x 60mm) 435.9cc/76hp= 5.735cc to make 1hp! 435.9cc/78hp= 5.588cc to make 1hp!

As the 440 Kawasaki Dyno Sheet I posted above shows, making Max [email protected], what the 618UL was turned at, also making [email protected] is more inline with Airplane use. 435.9cc/63hp= 6.919cc to make 1hp! 435.9cc/61hp= 7.145cc to make 1hp!

The 7cc to make 1hp Rule of thumb at 6500rpm is good for making hp for Airplanes! 435.9cc/7cc= [email protected] As the Dyno Sheet above shows, theirs made [email protected]

Yes, probably 12.0-12.5cr. The manual you Posted is very Good, gives Port Sizes, and Head cc. I agree 93+ Octane.

The only issue I see with it is finding those Pistons with the L Shaped Rings. I have walked many a Sled Swap meet and Sled Junk Yards and you don't see many of these. One thing good about Kawasaki's is they used a lot Parts the same in the Sleds and on 440 Jet Skies.

I would change out the Keihn Butterfly Carbs for Mikuni Flat Side Carbs myself. I just bought a New 38mm off eBay for $81. 34mm go for $40.

KAWASAKI 440 - 63hp at 6750rpms.jpg
 

Armilite

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What you don't seem to understand is these Kawasaki 340/440's were many different [email protected], 35hp, 40hp, 48hp, 63hp, 76hp, etc. Some used Mufflers and some used a Tuned Pipe! Same as the Rotax 277UL was rated [email protected] and also [email protected] There never was a 277UL rated at 6800rpm per the Roger guy posted above. The 277F Sled version was turned 6750rpm making 28hp using a Smaller 34mm Carb! The Type of Exhaust used makes a big difference in Performance! The 277UL 26hp version actually Dynoed Max [email protected] so when setting up a Prop for it you're are already using False Data! Never seen the 277UL [email protected] version Dynoed.

There is No Magical One Size Prop! It's usually best to use the Largest Prop your Plane can handle. But many people can't afford that Big Prop so they Buy what they can afford.

Rotax A/B Gear Drives set a president, Max (2) Blade is 68", Max (3) Blade 64". Just as the 2.58 is the most popular ratio for the A/B Gear Drive, 2.6 Ratio is the most popular to use with Belt Drives, 2.63 is the most used with the C&E HD Gear Drives.

Industry Standard rpm is Max 6500rpm for a Long Service Life!

Every Prop Lenght has a Max rpm it can turn before it goes Super Sonic! Higher the rpm = more Thrust, but also more Noise! Put one of the Free Sound Meter Aps on your Smart Phone and record the DB level at different rpm.

Now when I contacted Warp Drive a while back for a (2) Blade Prop for my 277UL [email protected], using the 2.0 Gear Drive, they recommended a 54" x 18! Now from the R&D Aero Dyno print we know it made Max [email protected] 6000/2= 3000rpm! Most Props CF falls between .75 and .85. Using .75 for CF in Calc shows. In the Calc, 54" x 22 seems the most optimal Prop. Needs 25.735hp so 25.4 won't unload the prop, and puts you at approximately 54.2 knots, Part 103 is Max 55 knots. Tune that 277UL to make Max Power, 29-30hp at 6500rpm and things change for the Prop. Prop rpm goes from 3000rpm to 3250rpm. A 54" Prop doesn't go Super Sonic till after 4,455rpm. The calc will let you know when it does. Static Thrust Calculator - STRC

A/B Gear Drives:
6500rpm/2.0= 3,250rpm

6500rpm/2.238= 2,904.3rpm - 6500/2.24= 2,901.7rpm

6500rpm/2.58= 2,519.3rpm

6500rpm/2.6= 2,500rpm

C&E HD Gear Drives:
6500/2.62= 2,166.6rpm Gives yo the most Thrust!

6500/3.0= 2,166.6rpm

6500/3.47= 1,873.1rpm

6500/4.0= 1625rpm

Rotax B Drive Gearbox Ratios(Ultralight News)
Rotax B Drive Gearbox Ratio Stamp
The drives ratios are 2.0:1, 2.238:1, and 2.58:1. The 2.58 to one ratio was generally used in ultralight applications when spinning props from 60 to 68 inches in length. The 2 to 1 and 2.238 to 1 ratio was used more on airboats and hovercraft when a smaller prop was used.

Lockwood. Even Gear Ratios aren't correct.
The Type B Gearbox's most popular gear ratio is 2.58 to 1. Ratios of 2.24 and 2.0 to 1 are also available where a smaller diameter must be used or more speed is desired. This gearbox is designed for Rotax 447 and 503 engines. Normally, the maximum prop diameter for a Type B gearbox is 68" x 2-blades or 64" x 3-blades. Anything larger and the engine will idle roughly below 2,000 rpm or will be hard to start.
 

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Armilite

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Roger Manns engine prop PSRU matrix (the single most trusted source for Kawasaki PSRU and prop information) for the 440a indicates 2.9:1 ratio and a 72 inch prop:
***************************************
These are some thrust check stats. that Roger got:
340 LC, 2.9 to 1 belt, 70X26 prop- 205 lbs. at 6800 RPM
340 FA, 2.8 to 1 belt, 68X26 prop- 190 lbs. at 6600 RPM
440A FA 2.9 to 1 belt, 72X32 prop- 225 lbs. at 6600 RPM
The stats. below with a shorter prop. are ok but not as good as above.
340 LC, 2.6 to 1 belt, 60X28 prop- 165 lbs. at 6800 RPM
340 FA, 2.6 to 1 belt, 58X26 prop- 155 lbs. at 6600 RPM
440A FA, 2.6 to 1 belt,60X28 prop- 160 lbs. at 6600 RPM

Note: The difference between a 340 and a 440 is
piston size, a 340 can be made into a 440.

I ABSOLUTELY do not recommend using any Propeller
Speed Reduction Unit(PSRU) that uses a 2.0 to 1 reduction. This sets up
harmonics that are dangerous. Several failures have been recorded. I also do not
recommend the 440B which is 48 hp but cannot be cruised between 5500 and 6000
RPM.

As shown above the best performance comes when using a longer prop.

How do these engines compare?
Rotax 277, 2.58 to 1 gearbox, 60X28 prop-160 lbs. at 6800 RPM
Rotax 503, 2.58 to 1 gearbox, 64X34 prop-200 lbs. at 6800 RPM
Rotax 503, 2.9 to 1 belt, 72X38 prop-260 lbs. at 6800 RPM

Most people who are dissatisfied with Kawasaki engine
packs are swinging short props with something below a 2.6 to 1 ratio. Much time
and money has gone into the short evaluation above but it proves that once set
up properly the 340 can't be beat for the money invested.

**********************************************************************

I can not find any ground adjustable props that size! My fisher 101 is normally equipped with a 60 inch prop (clearance). I can extend the undercarriage somewhat but I doubt I can fit a 72 inch prop no matter what I do...Am I missing something?
=========================

His 440A FA 2.9 to 1 belt, 72x32 Prop - 225 lbs. at 6600rpm/2.9 = 2,275.8rpm for Prop and if you dial down the CF to .603 to make his 225lbs needs 41.525hp.

72 x 32 Prop..jpg
 

Herbgh

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Messages
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Thanks for the info...I was hoping for a different HP/Torque curve...Those tuned pipes really bring it on....
 

n3puppy

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Messages
286
Thanks for the info...I was hoping for a different HP/Torque curve...Those tuned pipes really bring it on....
It may not be that bad. The high horsepower is due to the exhaust used not the engine itself.

Example - the 582UL and Snow 583 are basically the same engine.
The performance of the Snow 583 and your Snow 440D is very close on a hp/cc or BMEP comparison.

Your 440D engine and the 582UL have roughly the same exhaust port timing - 205 degrees.
Without getting technical - means they should be able to use similar exhausts.

PURE GUESS- but I believe that if you were to hook that Kawasaki engine up to a Rotax 582 aviation exhaust system you would get a very similar power curve.
Could yield around 49hp at 6500rpm using the same output numbers as the 582 -( hp/cc and BMEP)

D5A15CD1-AE7F-43A7-B0C9-E2B7AA24E88C.jpeg
 
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Armilite

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It may not be that bad. The high horsepower is due to the exhaust used not the engine itself.

Example - the 582UL and Snow 583 are basically the same engine.
The performance of the Snow 583 and your Snow 440D is very close on a hp/cc or BMEP comparison.

Your 440D engine and the 582UL have roughly the same exhaust port timing - 205 degrees.
Without getting technical - means they should be able to use similar exhausts.

PURE GUESS- but I believe that if you were to hook that Kawasaki engine up to a Rotax 582 aviation exhaust system you would get a very similar power curve.
Could yield around 49hp at 6500rpm using the same output numbers as the 582 -( hp/cc and BMEP)

View attachment 118686
==========================

397cc and 580cc isn't even close!

A General Rule when trying to adapt a Tuned Pipe from another Engine is to Always use one that was Designed for a bigger CC Engine and try to find one Close to your Max rpm use. Otherwise, you will Burn the Engine up. You will have to lengthen or Shorten the Tuned Pipe! There is a Formula for doing that! For a 397cc Engine a Good Tuned Pipe from a 503F/550F which were rated at 7000rpm would be best to use. AAens aftermarket 550F Tuned Pipe make +8hp over the Stock 550F Tuned Pipe.

Rotax UL Exhaust is not a Tuned Pipe, it's a Tuned Megaphone Header Exhaust. The 503UL Exhaust would probably be the Best to use for the 397cc Single.

Except your 583 (580.9cc) hp numbers are Wrong! The 583 was [email protected]! The 617 (617.2cc) was [email protected] and the 670 (669.2cc) was [email protected]!

583 is 580.9cc/97hp = 5.988cc to make 1hp at 7750rpm.

580.9cc/7cc= 82.985hp @6500rpm!

There is more to Look at than just Exhaust Port Timing, there is Rod Lenght, Exhaust Port Height, Width, Lenght, Max rpm desired, and desired hp to be made at that rpm!

A 503UL with a R&D Aero Tuned Pipe 496.9cc/62.3hp = 7.975cc to make 1hp! That was a very mild Tuned Pipe.

496.9cc making [email protected] +10% = 55hp!
496.9cc making [email protected] +20% = 60hp!
496.9cc making [email protected] +25% = 62.5hp!
496.9cc making [email protected] +30% = 65hp!
496.9cc making [email protected] +35% = 67.5hp!
496.9cc making [email protected] +40% = 70hp!

496.9cc/7cc= 70.985[email protected]!

Using the Peak Flow/hp calc: 4969cc at 6500rpm at 93% VE = 70.7hp.

So you got (2) ways to estimate hp at 6500rpm for Plane use! The 503 is 496.9cc/50hp= 9.938 variable! 397cc/9.938= [email protected] for a Muffler. But Racers tell me a Reed Fed Engine makes about 20% more hp than a Piston Port. 39.947hp +20% = 47.9hp with a 503UL Megaphone Header/Muffler Exhaust.
397cc at 93% VE turning 6500rpm = 57hp with a TUNED PIPE!
397cc/7cc = 56.714 hp@6500rpm = with a Tuned Pipe!

A 583/582UL with Rotax Ricks Tuned Exhaust is rated 79hp@6400rpm!

A 583 with an R&D Aeros Tuned Pipe made 76.9hp@6500rpm! Made [email protected] Made Max [email protected]! If you Graph the R&D Tuned Pipe it's not a very Smooth Power Band.

A 670 with an R&D Aero Tuned Pipe, and a Stock 1993 670 Dyno Sheet!
 

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n3puppy

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==========================

397cc and 580cc isn't even close!

A General Rule when trying to adapt a Tuned Pipe from another Engine is to Always use one that was Designed for a bigger CC Engine and try to find one Close to your Max rpm use. Otherwise, you will Burn the Engine up. You will have to lengthen or Shorten the Tuned Pipe! There is a Formula for doing that! For a 397cc Engine a Good Tuned Pipe from a 503F/550F which were rated at 7000rpm would be best to use. AAens aftermarket 550F Tuned Pipe make +8hp over the Stock 550F Tuned Pipe.

Rotax UL Exhaust is not a Tuned Pipe, it's a Tuned Megaphone Header Exhaust. The 503UL Exhaust would probably be the Best to use for the 397cc Single.

Except your 583 (580.9cc) hp numbers are Wrong! The 583 was [email protected]! The 617 (617.2cc) was [email protected] and the 670 (669.2cc) was [email protected]!

583 is 580.9cc/97hp = 5.988cc to make 1hp at 7750rpm.

580.9cc/7cc= 82.985hp @6500rpm!

There is more to Look at than just Exhaust Port Timing, there is Rod Lenght, Exhaust Port Height, Width, Lenght, Max rpm desired, and desired hp to be made at that rpm!

A 503UL with a R&D Aero Tuned Pipe 496.9cc/62.3hp = 7.975cc to make 1hp! That was a very mild Tuned Pipe.

496.9cc making [email protected] +10% = 55hp!
496.9cc making [email protected] +20% = 60hp!
496.9cc making [email protected] +25% = 62.5hp!
496.9cc making [email protected] +30% = 65hp!
496.9cc making [email protected] +35% = 67.5hp!
496.9cc making [email protected] +40% = 70hp!

496.9cc/7cc= 70.985[email protected]!

Using the Peak Flow/hp calc: 4969cc at 6500rpm at 93% VE = 70.7hp.

So you got (2) ways to estimate hp at 6500rpm for Plane use! The 503 is 496.9cc/50hp= 9.938 variable! 397cc/9.938= [email protected] for a Muffler. But Racers tell me a Reed Fed Engine makes about 20% more hp than a Piston Port. 39.947hp +20% = 47.9hp with a 503UL Megaphone Header/Muffler Exhaust.
397cc at 93% VE turning 6500rpm = 57hp with a TUNED PIPE!
397cc/7cc = 56.714 hp@6500rpm = with a Tuned Pipe!

A 583/582UL with Rotax Ricks Tuned Exhaust is rated 79hp@6400rpm!

A 583 with an R&D Aeros Tuned Pipe made 76.9hp@6500rpm! Made [email protected] Made Max [email protected]! If you Graph the R&D Tuned Pipe it's not a very Smooth Power Band.

A 670 with an R&D Aero Tuned Pipe, and a Stock 1993 670 Dyno Sheet!
Apparently you are not familiar with Kawasaki engines.
The 440D engine being discussed is a 436cc Twin (two cylinders)
Not a 397cc single (one cylinder.).

All of your mathematic calculations for a 397cc Single are invalid for this thread.

BTW - There are several versions of the Snow 583 - Carb, Exhaust and CR variations for different HP.
I chose a Formula 583 variation with 106hp @ 8000 since that is close to the same output of the Kawasaki 440D TWO CYLINDER engine. (Hp/cc and rpm)

E8D7D81E-D3D5-42C9-A58B-09AD0660DDC7.jpeg
 
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Armilite

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Apparently you are not familiar with Kawasaki engines.
The 440D engine being discussed is a 436cc Twin (two cylinders)
Not a 397cc single (one cylinder.).

All of your mathematic calculations for a 397cc Single are invalid for this thread.

BTW - There are several versions of the Snow 583 - Carb, Exhaust and CR variations for different HP.
I chose a Formula 583 variation with 106hp @ 8000 since that is close to the same output of the Kawasaki 440D TWO CYLINDER engine. (Hp/cc and rpm)

View attachment 118779
====================================

I'm well aware of these Kawasaki Engines! The Thread is "440 Kawasaki PSRU design, parts, plans, sources" not 583 Skidoo Engines. My Point was these different Engines all use different Exhaust Port Durations! So you can't just Bolt on any Tuned Pipe! There is a Formula to get you close!

No Way any 436cc Engine is going to make the same hp at the same 8000rpm as a 580cc Engine. No Engine for Airplane use uses 8000rpm either and last very long! The vast majority of Stock 583's used a Single Tuned Pipe, and they all used the same 11.5cr. They did use some different Size Carbs. Stock 583, 617, 670 Engines were rated at 7750rpm. The 583 was [email protected]
 

n3puppy

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Joined
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Messages
286
====================================

I'm well aware of these Kawasaki Engines! The Thread is "440 Kawasaki PSRU design, parts, plans, sources" not 583 Skidoo Engines. My Point was these different Engines all use different Exhaust Port Durations! So you can't just Bolt on any Tuned Pipe! There is a Formula to get you close!


Apparently you did not read my previous post. If you had you would know

1) The original poster, Herbgh, said he was hoping for a different curve - 8200 rpm too much.
2) My post was offering a way to get a better aviation curve 6500rpm
3) The STOCK Kawasaki 440D makes about the same HP/CC as the 583
583 = 5.5cc/hp @ 8000. Kawasaki 440D = 5.6 cc/[email protected]
4) The Kawasaki 440D and 582UL (and 583) have exhaust durations of approx 205 degrees

So by following standard pipe design formulas - an exhaust system that supports a 582UL at 6500rpm will be the correct length for a Kawasaki 440D because the durations are virtually the same.
It's just math.

The beauty of the Rotax wide band tuned exhaust is that it was designed for actual aviation use - not snowmobiles. Wide Band tuned exhausts are very tolerant of exhaust duration differences.
Rotax muffler canister same for all engines. Slight difference in system overall length (1.5 inches)
277-503 same exhaust system (168 to 189 degree duration)
532-582 same exhaust system (190 or 205 degree duration)

At same 205 degree Duration - potential power output using a 532/582UL exhaust ....
A 582 making 65hp @6500 rpm = 8.9 hp/cc @112.1BMEP
A Kawasaki 440D making [email protected] 6500 = 8.9cc/hp @ 112.4 BMEP

1347D3D7-BB71-4E8E-923C-4859DFAC2170.jpeg3A098D60-8EBE-493E-9607-E51787C33655.jpeg
 
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Armilite

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Apparently you did not read my previous post. If you had you would know

1) The original poster, Herbgh, said he was hoping for a different curve - 8200 rpm too much.
2) My post was offering a way to get a better aviation curve 6500rpm
3) The STOCK Kawasaki 440D makes about the same HP/CC as the 583
583 = 5.5cc/hp @ 8000. Kawasaki 440D = 5.6 cc/[email protected]
4) The Kawasaki 440D and 582UL (and 583) have exhaust durations of approx 205 degrees

So by following standard pipe design formulas - an exhaust system that supports a 582UL at 6500rpm will be the correct length for a Kawasaki 440D because the durations are virtually the same.
It's just math.

The beauty of the Rotax wide band tuned exhaust is that it was designed for actual aviation use - not snowmobiles. Wide Band tuned exhausts are very tolerant of exhaust duration differences.
Rotax muffler canister same for all engines. Slight difference in system overall length (1.5 inches)
277-503 same exhaust system (168 to 189 degree duration)
532-582 same exhaust system (190 or 205 degree duration)

At same 205 degree Duration - potential power output using a 532/582UL exhaust ....
A 582 making 65hp @6500 rpm = 8.9 hp/cc @112.1BMEP
A Kawasaki 440D making [email protected] 6500 = 8.9cc/hp @ 112.4 BMEP

View attachment 119193View attachment 119194
==============================

I show for the 532UL and 582UL 190 Degree Exhaust Duration, not 205. No matter if they have the same Exhaust Duration the Tuned Pipe is Designed for a Specific Max RPM, so depending on rpm used, the Lenght will change +/- inches. Example: Both a Skidoo 335 (155 Duration) rated at 5500rpm, a Single, and the 670 Twin (180 Duration) rated at 7750rpm had the same 78mm Bore & 70mm Stroke. If you used the Tuned Pipe Lenght Formula Chart if you wanted to use the 670 180 Duration Tuned Pipe Designed for 7750rpm = 39.5" and if you wanted to use it on the 335 with its 155 Duration and maybe turn it a higher 6500rpm = 40.5", so you would add 1.0" to its length. The 670 Tuned Pipe 180 Duration Designed for 7750rpm = 39.5" and the 277F 189 Duration turned 9200rpm = 34.9". So 40.5 - 34.9 = 5.6" it needs to be Shortened.

For Airplane use your better off using a Tuned Pipe Designed for 7000rpm, like a 380F, 440F, 503F, 550F. Most Sleds Exhaust are Designed for 7750rpm+. Just as the Kawasaki 440 Free Air/Fan Cooled would make a better choice. 440 made [email protected] 436cc/7cc= 62.3hp if Designed for 6500rpm. Sled Pipe made Max [email protected] Could you turn a Kawasaki 440 on a Plane using the same 6750rpm, Yes!

Engines, don't know their Brand Name or if they're an A, B, C, D, etc., all they know is CC, RPM, CFM, CR, and Port Duration!

583 = <-- YOU SAY 205
532UL = 190
582UL = 190 <--- YOU SAY 205
277UL = 189
503UL = 188
377UL = 182
670 = 180
447UL = 168
618UL =
462UL =
===============
OLD SKIDOO SINGLES
335 = 155
250 =
292 TNT =
299/300 =
318/320 =
340 TNT =
================

KAWASAKI 340 = 194
KAWASAKI 440 = 194
KAWASAKI 440 JS = 165

KAWASAKI 440D = 205 You say.

Rotax's UL Exhaust is not a Tuned Pipe it's a Tuned Megaphone Header/Muffler Exhaust. Better than a Straight Pipe with a Muffler. There are (3) Types of 2 Stroke Exhaust, Straight Pipe into a Muffler, Megaphone Header/Muffler Exhaust, and a Tuned Pipe Exhaust.
 

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n3puppy

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I show for the 532UL and 582UL 190 Degree Exhaust Duration, not 205.

Engines, don't know their Brand Name or if they're an A, B, C, D, etc., all they know is CC, RPM, CFM, CR, and Port Duration!

There are (3) Types of 2 Stroke Exhaust, Straight Pipe into a Muffler, Megaphone Header/Muffler Exhaust, and a Tuned Pipe Exhaust.
To be clear for anyone building a pipe - 582UL exhaust duration = 205 Degrees.
Theoretical CR =11.5 and Effective CR= 5.75
Wallace Racing: Dynamic Compression Ratio Calculator
Your 190 degree would be Effective CR 6.46 NOT the 5.75 of the 582UL.

There are over 20 different Kawasaki 340/440 engines.
Herbgh has the 440D It is closest to the 582UL in Port Duration.

Assuming he finds or makes a 2 into 1 exhaust manifold to replace the twin pipes - The Proven Rotax "TUNED" aviation exhaust that has worked well for decades on the 582UL at 6500rpm will also work on his Kawasaki 440D at 6500rpm because the exhaust duration is approximately the same.

Exhaust systems don't need POINTY ENDS to be "TUNED". Any exhaust that changes power as length changes is "TUNED". Vintage snowmobile racers know the length of the "STRAIGHT PIPE" into the muffler makes a difference.

Aviation Experts have written articles explaining the importance of maintaining the "TUNED" length of the Proven Rotax Aviation "TUNED" exhaust system.

A5C39C45-5F57-4506-BA50-1DDB049955B1.jpeg60F6FE73-84B5-4C7E-8A7E-231C6471723C.jpegBB38C77B-3082-43EB-ABAD-9CCC19E4510B.jpegC6AB5629-328E-4E7D-83EF-288CAA64479D.jpeg
 
Last edited:

Armilite

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Messages
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To be clear for anyone building a pipe - 582UL exhaust duration = 205 Degrees.
Theoretical CR =11.5 and Effective CR= 5.75
Wallace Racing: Dynamic Compression Ratio Calculator
Your 190 degree would be Effective CR 6.46 NOT the 5.75 of the 582UL.

There are over 20 different Kawasaki 340/440 engines.
Herbgh has the 440D It is closest to the 582UL in Port Duration.

Assuming he finds or makes a 2 into 1 exhaust manifold to replace the twin pipes - The Proven Rotax "TUNED" aviation exhaust that has worked well for decades on the 582UL at 6500rpm will also work on his Kawasaki 440D at 6500rpm because the exhaust duration is approximately the same.

Exhaust systems don't need POINTY ENDS to be "TUNED". Any exhaust that changes power as length changes is "TUNED". Vintage snowmobile racers know the length of the "STRAIGHT PIPE" into the muffler makes a difference.

Aviation Experts have written articles explaining the importance of maintaining the "TUNED" length of the Proven Rotax Aviation "TUNED" exhaust system.

View attachment 119501View attachment 119502View attachment 119503View attachment 119504
===================================

Your Calc is for a 4 Stroke not a 2 Stroke! 2 Strokes use 532UL/582UL Theoretical CR =11.5 and Effective CR = 5.75, not Static Compression.

That Tuned-Length does not Work for all the same Engines, 277UL, 377UL, 447UL, 503UL! They are rated at different rpm, use different Port Durations! Heck man even you can SEE on these Dyno prints the 277UL isn't making even the full [email protected] It started losing power at 5500rpm! Even the 503UL made max [email protected]! At 6500rpm it was only making 49.6hp.

I have said many times the LENGHT of the Exhaust makes a difference, whether it's a Straight Pipe, a Megaphone Header, or a Tuned Pipe used! Even Old Sleds that used Can Mufflers, some used different SIZE TUBES going to them Cans and the Insides had different SIZE Holes, it's called BACK PRESSURE.

You don't seem to understand the difference between a Straight Pipe vs a Megaphone Header Pipe(Rotax) which then both dumps into a MUFFLER. I gave you the (3) Different Types of Examples to LOOK at! Most Rotax 2 Stroke Exhaust Ports fall between 26mm to 32mm!

ROTAX 277UL
STROKE = 66mm
ROD LENGHT = 120mm
EXHAUST PORT HEIGHT ABOVE BDC:
30.4055mm = 187 DEGREES

KAWASAKI 340/440

STROKE = 60mm
ROD LENGHT = 110mm
EXHAUST PORT HEIGHT ABOVE BDC: Chart shows 440 at 29.1mm = 192.327 DEGREES! The last I knew if the 582UL is 205 and Kaw 440 is 192 their Port Durations are different.

26mm = 180.649 DEGREES
27mm = 184.446 DEGREES
28mm = 188.212 DEGREES

29mm = 191.954 DEGREES
30mm = 195.675 DEGREES
31mm = 199.380 DEGREES
32mm = 203.074 DEGREES

33mm = 206.761 DEGREES
34mm = 210.446 DEGREES
35mm = 214.133 DEGREES


532UL/582UL <----- I don't have a 582UL Cylinder handy to Measure at the moment. A 1996-98 Seadoo 587 Exhaust Port was 32.3mm = 195.755 Duration. A 1995 587 was 30.1mm = 188.044 Degrees. So I doubt the 582UL was 205, but it could be, Measure it then you know for sure, you can see they used different Specs on the Seadoo 587 which is the same bore & stroke as the 582UL.

STROKE = 64mm
ROD LENGHT = 125mm
EXHAUST PORT HEIGHT ABOVE BDC:
25mm = 169.714 DEGREES
26mm = 173.376 DEGREES
27mm = 177.001 DEGREES
28mm = 180.592 DEGREES
29mm = 184.154 DEGREES
30mm = 187.692 DEGREES

31mm = 191.208 DEGREES
32mm = 194.708 DEGREES
33mm = 198.194 DEGREES
34mm = 201.671 DEGREES

35mm = 205.142 DEGREES
36mm = 208.611 DEGREES
37mm = 212.082 DEGREES
38mm = 215.558 DEGREES
39mm = 219.043 DEGREES
40mm = 222.542 DEGREES


Port Timing Duration Calculator

When building a Tuned Pipe you have COLD Port Timing Duration and you have HOT Port Timing Duration. The Numbers Change a little.
 

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n3puppy

Well-Known Member
Joined
Jun 25, 2019
Messages
286
Your Calc is for a 4 Stroke not a 2 Stroke! 2 Strokes use 532UL/582UL Theoretical CR =11.5 and Effective CR = 5.75, not Static Compression.

You don't seem to understand the difference between a Straight Pipe vs a Megaphone Header Pipe(Rotax) which then both dumps into a MUFFLER.

EXHAUST PORT HEIGHT ABOVE BDC: Chart shows 440 at 29.1mm = 192.327 DEGREES! The last I knew if the 582UL is 205 and Kaw 440 is 192 their Port Durations are different.

When building a Tuned Pipe you have COLD Port Timing Duration and you have HOT Port Timing Duration. The Numbers Change a little.
Surprised you don't know Static compression and theoretical compression are the same thing.
4 stroke intake closes or 2stroke exhaust closes = Effective (corrected) Compression.

Since you don't believe the calculator - Exhaust duration FOR THE 582UL using a different method.
1) [email protected] 27.65cc head volume at port 64mm from TDC = 11.5CR
2) [email protected] head volume at port 28.93 from TDC = 5.75CR
3) 64mm stroke/125mm rod @ 28.93mm = 77.31degrees x2 = 154.62 degrees CLOSED
4) 360 - 154.62 = 205.38 degrees OPEN duration for the 582UL

I noted there were 20+ models of Kawasaki 340/440. The port map you picked in not for the Kawasaki LTD 440D engine we are discussing. Also the 29.1mm number you used is for the intake port. Exhaust durations are calculated from the exhaust port dimensions not Intakes.
The Correct 440D port diagram shows port distance above BDC is 32.6mm
Per your port calculator the Kawasaki 440D duration = 205.287 degrees
The 582UL at 205.38 and Kaw 440D at 205.287 Port Durations are almost the SAME

Rotax understands various types of Exhaust systems - they know that wide power band exhausts are tolerant of different durations. That's why only two groups of exhausts - 277-377-447-503. And 532/582
I fully understand the differences between an expansion chamber and Megaphone.
The different ways the two work is why Rotax decided to use one vs the other.

For aviation use, they wanted lower HP levels @6500 that gave reliability to their engines because peoples lives depend on them. They chose not to use high output Expansion chambers - They chose to use the less aggressive tuned megaphone muffler because it is better for swinging a prop.

BTW- Physical port duration doesn't change with Pipe Temp as you suggest - Wave Speed does. That's why different lengths are used based on intended use and pipe heat (race or trail). Wide range pipes are tolerant of heat changes in the exhaust like full power take-off vs lower power cruise.
 

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Lucky Dog

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Joined
Aug 4, 2021
Messages
50
@n3puppy: Thanks for the wealth of exhaust timing information. I'll keep all of it in my files. It's a rare moment to read informed technical explanations about the juggling act that happens between the exhaust system and the cylinder of a running two stroke. Your statement that Rotax designed their exhaust to maximize torque for turning the prop is not quite true. As a long time designer and builder of two stroke racing pipes, I can report that an expansion chamber type exhaust is always the better choice for maximizing torque, HP and efficiency - and that configuring one to provide power delivery over a sufficiently wide RPM range is also a simple task. The volume and length required to make such a system, however, in addition to the noise they produce, is not compatible with Sport or UL aircraft. Rotax's decision to use an abridged, two-into-one exhaust design makes for a more compact, lighter weight, much more quiet exhaust system at the expense of some of their engine's performance. I agree with Rotax's compromise for all those reasons, but I cringe each time I hear the aviation community discount 60 years of two stroke exhaust technology as a witch hunt - shouting from the pulpit of an industry, trapped in the exhaust-scavenging stone age. Once again, thanks for some fresh air on the subject.
 

n3puppy

Well-Known Member
Joined
Jun 25, 2019
Messages
286
As a long time designer and builder of two stroke racing pipes, I can report that an expansion chamber type exhaust is always the better choice for maximizing torque, HP and efficiency - and that configuring one to provide power delivery over a sufficiently wide RPM range is also a simple task. The volume and length required to make such a system, however, in addition to the noise they produce, is not compatible with Sport or UL aircraft.
Lucky Dog -Great to have an experienced pipe builder on board.
My experience with pipes has been from snowmobile and sports car racing. Its a world of max hp with little consideration of the drawbacks of Peaky performance. CVT belt drives mask a lot of pipe quirks.

I struggle with a simple explanation of the curve required for a fixed pitch prop. Easy to say wide band vs peaky but what does that look like? Some people say that's its a "Straight Line" with constant hp per rpm increase over a wide range of rpm - say 4000-6500. Similar drop off after peak.

I think of it as a wide flat area at peak - very little change in hp over a range of say 1000 or so rpm. As the prop load/rpm changes with aircraft attitude changes, the engine isn't hunting because of the pipe curve.
The 50hp 503UL only varies about 2.5hp from 6000-7000rpm.
The old 55hp 582UL only about 4hp difference from 5250-6500rpm
Unfortunately when I try to explain it - it sometimes sounds like maximizing torque.
Worse.. I've even used a diagram from AAEN that shows the flat peak area on their "Torquer" pipe

Your explanation of the compromises of the Rotax exhaust is the best I've heard
C44B0045-39CD-439B-9387-382242703C4D.jpegE7197CAD-3D8D-4B37-BEE0-8DB0E25BE947.jpeg01D715AE-EA27-48CB-9911-2E4BD882B591.jpeg
 

simflyer

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Joined
Sep 24, 2015
Messages
238
Location
Moravia
I like to get drawings of 582 tuned pipe and belt PSRU, for use with 600ccm ArctiCat Suzuki engine
Actually are available 800ccm Rotax engines, so also pipe and PSRU, could be useful.
 

Lucky Dog

Well-Known Member
Joined
Aug 4, 2021
Messages
50
Lucky Dog -Great to have an experienced pipe builder on board.
My experience with pipes has been from snowmobile and sports car racing. Its a world of max hp with little consideration of the drawbacks of Peaky performance. CVT belt drives mask a lot of pipe quirks.

I struggle with a simple explanation of the curve required for a fixed pitch prop. Easy to say wide band vs peaky but what does that look like? Some people say that's its a "Straight Line" with constant hp per rpm increase over a wide range of rpm - say 4000-6500. Similar drop off after peak.

I think of it as a wide flat area at peak - very little change in hp over a range of say 1000 or so rpm. As the prop load/rpm changes with aircraft attitude changes, the engine isn't hunting because of the pipe curve.
The 50hp 503UL only varies about 2.5hp from 6000-7000rpm.
The old 55hp 582UL only about 4hp difference from 5250-6500rpm
Unfortunately when I try to explain it - it sometimes sounds like maximizing torque.
Worse.. I've even used a diagram from AAEN that shows the flat peak area on their "Torquer" pipe

Your explanation of the compromises of the Rotax exhaust is the best I've heard
View attachment 119579View attachment 119580View attachment 119581
So, your question is the elephant in the 582 room. 99 percent of Rotax users fly fixed pitch props, and perhaps more important, the useful rpm bandwidth of the 582 with a fixed pitch is only 1000 RPM - which is also the target range for a good pipe. Typically, 5100 is about a slow as anyone can cruise and most climb out at 6100. So, a tuned pipe for the 582 could be much more aggressive than conventional thinkers propose and the extra power should come with no changes in fuel efficiency.

The dark side of the equation is that tuned pipes would require specific changes in the needles, needle jets and main jets, as well as re-pitching the prop to both take advantage of the new power curve, and to re-map the EGT and CHT values to play well with the new setup. Even if the exhausts included the necessary parts and instructions, it is unlikely that the Rotax aviation community would adhere to the recommendations. A couple of forum notorieties with blown engines could ruin three years of careful development in three days. Maybe the best advertising for such a project would be to build a 7000 rpm rave-valve 582 with a screaming set of pipes for a STOL Kitfox owner who wants to drag race with the Supercub millionaires. It would sure sound awesome at full song!
 

n3puppy

Well-Known Member
Joined
Jun 25, 2019
Messages
286
So, your question is the elephant in the 582 room. 99 percent of Rotax users fly fixed pitch props, and perhaps more important, the useful rpm bandwidth of the 582 with a fixed pitch is only 1000 RPM - which is also the target range for a good pipe. Typically, 5100 is about a slow as anyone can cruise and most climb out at 6100. So, a tuned pipe for the 582 could be much more aggressive than conventional thinkers propose and the extra power should come with no changes in fuel efficiency.
Good Points - Except there is a second potential elephant in the room. Planes don't always fly at full throttle. Pilots pull the throttle pack to cruise power/RPM. Most folks look at published dyno chart (full throttle) and think if they find 75% power on the chart they also have the rpm for 75% power at partial throttle.

Couple Problems - First, Prop load vs rpm is a cubed factor equation - 75% load is roughly 90% rpm and 50% load roughly 80% rpm. Engines/Pipes behave different at part throttle. Years ago SnowTech did a comparison Dyno Run of Arctic 800 at Full throttle, and at 1/2 throttle. Obviously reduced peak output.
BUT - for any given hp - more RPM needed [email protected] vs [email protected] part throttle.
The second potential elephant is - if you shoot for max power at 6500rpm - what's the pipe going to do at part throttle settings around 5900 rpm (75%) or 5600rpm (65%)

There was one 582UL exhaust that was developed for aircraft by R&D Aero. Curve vs stock is interesting.

Given your experience - May want to start a thread in the two cycle section so folks wanting to look at pipes for any engine have a reference thread for the pro's, con's, and potential pitfalls along the way.
B2FA1EDF-D300-4E3F-A6BC-D7AEFEE2A4F1.jpeg42E3062C-138F-43D3-AFBD-8556E2FE25F6.jpegAA0BE65F-AA9E-473B-A218-6BDFBC30BB51.jpeg
 
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Armilite

Well-Known Member
Joined
Sep 5, 2011
Messages
3,674
Location
AMES, IA USA
Surprised you don't know Static compression and theoretical compression are the same thing.
4 stroke intake closes or 2stroke exhaust closes = Effective (corrected) Compression.

Since you don't believe the calculator - Exhaust duration FOR THE 582UL using a different method.
1) [email protected] 27.65cc head volume at port 64mm from TDC = 11.5CR
2) [email protected] head volume at port 28.93 from TDC = 5.75CR
3) 64mm stroke/125mm rod @ 28.93mm = 77.31degrees x2 = 154.62 degrees CLOSED
4) 360 - 154.62 = 205.38 degrees OPEN duration for the 582UL

I noted there were 20+ models of Kawasaki 340/440. The port map you picked in not for the Kawasaki LTD 440D engine we are discussing. Also the 29.1mm number you used is for the intake port. Exhaust durations are calculated from the exhaust port dimensions not Intakes.
The Correct 440D port diagram shows port distance above BDC is 32.6mm
Per your port calculator the Kawasaki 440D duration = 205.287 degrees

The 582UL at 205.38 and Kaw 440D at 205.287 Port Durations are almost the SAME

Rotax understands various types of Exhaust systems - they know that wide power band exhausts are tolerant of different durations. That's why only two groups of exhausts - 277-377-447-503. And 532/582
I fully understand the differences between an expansion chamber and Megaphone.
The different ways the two work is why Rotax decided to use one vs the other.

For aviation use, they wanted lower HP levels @6500 that gave reliability to their engines because peoples lives depend on them. They chose not to use high output Expansion chambers - They chose to use the less aggressive tuned megaphone muffler because it is better for swinging a prop.

BTW- Physical port duration doesn't change with Pipe Temp as you suggest - Wave Speed does. That's why different lengths are used based on intended use and pipe heat (race or trail). Wide range pipes are tolerant of heat changes in the exhaust like full power take-off vs lower power cruise.
=============================

Your right I must have looked at the wrong column. Durations are close. But my Point was, sticking on a Straight Pipe with a Muffler vs using a Rotax Megaphone Header Muffler is not going to Gain you much in hp vs using a Tuned Pipe. Just as the Kawasaki 440D used a much Higher [email protected] rating as did the Skidoo 580,582,583 Sled Engines, neither of them Sled Exhaust would make a Good Exhaust for our Max 6500rpm use! The 503UL was 496.9cc/49.6hp= 10.0cc to make 1hp. The Kawasaki 440D with the 503UL Exhaust was 435.9cc/10cc= [email protected] at the very Best. Most were considered [email protected]! As you said, there were many different Kawasaki 440's made, Free Air, Fan Cooled, Water Cooled, Single Plug, and Dual Plugs, but they used the same Bore & Stroke & Rod Length, with different Size Carbs and maybe different Porting, which can change Port Durations a little.

All of these 2 Strokes, used on Planes Swinging a Prop Idle Best at 2000rpm, and really don't start making usable hp till about 3500+rpm! So Useful Power Range is 3500rpm to 6500rpm, but even that 6500rpm is only used for Takeoff 2-5min then reduced. While each Plane has different Specs, and Pilots all Weigh different and start out at Different Altitudes means different hp made! A USA Part 103 has a minimum Stall Speed with a 170lb Pilot of 24 knots (27.6mph), at what [email protected] is it making? I would guess between 18-20hp? The Stock 277UL was making 20.3hp@5250rpm, 17.9hp@5000rpm, 15.1hp@4750rpm! People Heavier than 170 lbs, and most are today, would need more hp to stay above their Planes Stall Speed.

A Good Example is the 532UL (72mm x 64mm) 521.3cc rated [email protected] and the 582UL (76mm x 64mm) 580.9cc made [email protected], = 1hp difference for 59.6cc difference. Some People considered the 532UL as a perky engine, never had any dealings with one, and the 582UL with the same Rotax UL Exhaust Smoothed it out. R&D Aero made a 582UL Tuned Pipe that made around [email protected], a 15hp Gain! Rotax Rick has a Tuned Pipe now for the 582UL/583 RAVE making [email protected], a 14hp Gain!

The Stock 277UL was rated [email protected] yet Dynoed Max [email protected], so don't tell me Rotax knew what they were doing with their Megaphone Header Exhaust! Engine Companies don't Build Engines to make you HAPPY, they Build Engines to fit into HP Categories! YOU, the Consumer wouldn't Buy their next Latest and Greatest 377UL (35hp) for even more $$$, more Weight, if you knew your 277UL could make [email protected] with a Good Tuned Pipe. The 277UL can also be Big Bored to make even more CC = More HP! Max is (82mm x 66mm) 348.6cc/7cc= 49.8hp@6500rpm! But you/they can also Stroke these 277UL Engines, (82mm x 70mm) 369.8cc/7cc= [email protected] if they wanted to make you/us Happy! The 377UL/380HO (62mm x 61mm) 368.4cc/7cc= [email protected] which it did per the Dyno Sheet. Which also covered their 447UL ([email protected]) and their 503UL ([email protected]).

It's Clearly Obvious a Kawasaki 440 D with the Kawasaki 440 Free Air Tuned Pipe Designed for 6750rpm would be a better Choice making 61hp@6500rpm, made Max [email protected]!

No Tuned Pipe is going to be 100% Perfect that was Designed for different Engine Specs. Every Thousandth of an Inch/mm is Important in the Design! That's Why there are a lot of Bad Tuned Pipes in the World! IF, we had a Dyno to use we could experiment with some of these Rotax UL exhausts to see how they could be improved to make the Full Power there rated at. For the 277UL it probably needs to be Longer since per the Dyno Sheet it starts losing hp after 5500rpm. Spacers in 1.0" Increments could be made up and Tested. A Wood Bar Dyno could also be used. Pick your Max [email protected] you want to use. It was avg 2.8hp per +250rpm till 5500rpm. Was making [email protected] +2.8hp = [email protected], +2.8hp makes [email protected], +2.8hp makes [email protected] 6250rpm, +2.8hp makes [email protected] You do have some Parameters [email protected] and [email protected], to use, and then you the Wood Bar Formula. Use a Simple Tach with the Wood Bar dyno. Same with the Rotax Megaphone Header Muffler Exhaust! That's Why, the 277UL doesn't make the Full [email protected] Why the other 277UL made [email protected] as they say. Never seen one Dynoed! The different Exhausts used. You would have to have both Exhausts to compare and not many people are willing to cut them open to see what's different inside.

There are other Brand Name Engines being used on Airplanes using Tuned Pipes for the last 15 years. R&D Aero made most of their Tuned Pipes in the early '90s almost 30+ years ago. Some were Good, some were Bad!
 

n3puppy

Well-Known Member
Joined
Jun 25, 2019
Messages
286
=============================
The 503UL was 496.9cc/49.6hp= 10.0cc to make 1hp. The Kawasaki 440D with the 503UL Exhaust was 435.9cc/10cc= [email protected] at the very Best.

As you said, there were many different Kawasaki 440's made, Free Air, Fan Cooled, Water Cooled, Single Plug, and Dual Plugs, but they used the same Bore & Stroke & Rod Length, with different Size Carbs and maybe different Porting, which can change Port Durations a little.

The Stock 277UL was rated [email protected] yet Dynoed Max [email protected], so don't tell me Rotax knew what they were doing with their Megaphone Header Exhaust!
Comparing the Kawasaki 440D with the 503UL is questionable. A 503UL has a different exhaust duration.
The 582 and 440D have 205 degree exhaust duration
A 582 making 65hp @6500 rpm = 8.9 hp/cc
A Kawasaki 440D making [email protected] 6500 = 8.9cc/hp

The Kawaski SB440 port diagram previously posted is the wrong port Map for the 440D engine. - Using the correct port map is very important when designing an exhaust. Kawasaki 440 Twin engines have port durations from 170 to 205 degrees. A pipe could be 9 inches too long or short if the wrong map was used as a model.

As far as the 277UL goes - I would say Rotax was right on the money - they knew exactly what they were doing with their tuned exhaust. Any engine that independently dynos within One Tenth of One Hp and within 100 rpm is pretty close, especially when simple rounding errors are considered.
Published 19.0Kw = 25.47942 hp
Published [email protected]
R&D Dyno [email protected]

It will be interesting to see how close you are to one tenth of a HP when you finish building/porting/piping/dynoing your [email protected] Rotax 277UL

3174FA79-258A-4DD6-902B-368ACAF5CABD.jpeg8B2E58CE-CE11-4C66-99F6-BF8FDD9FB8A8.jpegED30977C-B0AB-4D8B-BEDE-2357D495A666.jpegA2EDDCBB-B33E-4C74-866D-E7541D8DD73E.jpeg
 
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