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Author Topic: Es-Kape 1.0 upgrade to Briggs & Stratton Animal 206cc Kart Racking Engine  (Read 762 times)

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Offline voipwell

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Mokai is bound by epa rules in engine selection.  But I would like 2.0 performance with 1.0 weight.  I picked the animal because of the torque chart.   The Subaru and Kholer peak horsepower is below 3600 rpm.  The peak torque even lower than that in the 2k range.  The animal has both it's torque and hp peaking in the 4-5k range peaking at 5k.  And,  it's built to withstand brutal beatings with racing parts designed to withstand up to 7500 rpm.  The coil limits the rpm to 6100 on the sealed racing version.  The unsealed animal can spin over 7500k.  I believe to 12k.  Sealed is a seal they put on the engine like the seal on your electric meter.  Sealed 206 engines can race in events that sanction sealed 206 engines. 

In the short year playing with Mokais,  my theory is they have enough hp but they could use more rpm. I believe it is not the jet loads on the engine preventing 1.0 subaru from going faster.  It is the ability to turn fast enough because of the engine design limit.  It simply can't bring it's 7 hp to the 4500 rpm party.   2.0 spins at 4550 at the impeller where 1.0 spins at about 4k.  Subaru spins that prop at 4k even though according to it's torque chart it is pushing the prop with 4 hp at that rpm.  The other 3 are being used to turn the engine that fast.  So, that rabbit hole led to the animal and other performance engines.

So i'm testing the theory that a 1.0 with 2.0 power at 1.0 weight would be a good companion to a 2.0. It may have more of the original skinny water advantages than beefy 2.0.

There are EPA options available like Tillotson, which are honda  clones with racing components.  They are advertised at 10 hp stock. 
But their peak HP occurs at the 4-5K range again so if subaru can do 18 with 3-4hp at 4k then imagine what animal at 4,600 will do on the same boat where 4600 would be it's intersection of torque and HP peaks.  I don't believe i should run the pump any faster than what Mokai runs the 2.0 pump at.  But,  since my 1.0 is not under warranty because i bought it used,  if i break it,  i pay for it.

The first step is to get the motor mounts on the animal.  They attach from the sides to the block using the side cover bolts instead of the bottom mounting bolts.  We'll have to see how things line up.  One thing to note,  i took the engine compartment to the kart shop to see if it would fit and the only problem looked like the valve cover touched the side of the engine compartment.  I saw a previous post on this forum where they heated up the plastic and bent it out a little bit with a 2x4.

Briggs also puts this engine in some snowmobiles.  And i saw a video where the guy mentions a low profile valve cover and bingo they make one so no clearance problem. 


I'm hoping this provides a path for Mokai owners that need to save 25 lbs to get their boat to plane.  The ones that don't care about planing are lucky and there are tons of uses for a slower mokai.  Mokai 2.0  appears to need to achieve 19-20 mph to plane for me and my wife.  She can get to 18 in 1.0 so just need to spin that impeller at the speed they are spinning 2.0 (4550) and should go about 27. 


Offline happul3

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Subaru spins that prop at 4k even though according to it's torque chart it is pushing the prop with 4 hp at that rpm.  The other 3 are being used to turn the engine that fast.  So, that rabbit hole led to the animal and other performance engines.


Are you looking at the right chart? The one I have for EX21D shows exactly 7hp max horsepower at 4000 rpms.

Offline voipwell

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Is this the one you are looking at?  I marked it where 7 hp ends. 
The blue area is the recommended output range.  Those two points that are marked continuous output are the maximum torque at 3k and maximum hp at 3600.  They can say anything they want in the white area of the diagram regarding maximum but the we run our Mokai's at an rpm over 3600 which results in lost hp.  4.75 at 3600 and it looks like 2.5 hp at 4000.  Ever notice when the grate completely clogs the rpm is almost the same as when it is clear.  The motor is not under a huge load.  If it was there would be a significant rpm difference inside the water and outside the water.  I'd be glad to discuss the chart and how i may be misreading it but i looked at a lot of charts.  Look at this one for the animal.

Offline Painlesstom

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This will be exciting to see. Hope you will post pics of your progress. I've been wanting to see what an animal motor would do in any of these hulls, but the 1.0 would be the best candidate for speed. Is your animal electric start with a charging system? That seems to be the limitation with RPM on a lot of these motors when a charging system is required, stock flywheels don't like to go past 4500 rpm. I think 5000 rpm would be the max I would push one. You should be fine if you can hit 4500 though, I hope you see that with a tight wear ring. 1.0 would be flying at that RPM.
Tom

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Offline voipwell

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The chart says maximum hp 7  rpm 4000 but they don't say maximum 7 hp at 4000 rpm.  They are  two separate items put on the same line i hope for saving space and not deceiving.  You would really believe that unless you looked at the torque chart.  It's a 7 hp motor that can't operate above 5 hp.  Even though it says recommended output range it still shows that the hp drops dramatically after 3600 rpm.  This is a fine point that i stumbled across by hearing the big difference in sound between the 1.0 and 2.0 in the 2.0 review video.  I always assumed it was 7 hp @ 4000 rpm until i really read about the relationship between torque and hp.  Then it became apparent what it would take to get 1.0 fast.  4500 rpm.  Subaru just can't spin that fast without load.

Offline voipwell

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Flywheel is rated at 7500 to 10000.  Electric Start and charger.  It is a factory option but for science i must.  But the reason I'm doing it is because i asked the guy would it last and what makes a kart engine wear out.  He said RPM.  When i said 4500 rpm he said no,  he meant over 6k rpm and iat 4500 it will last a long time.  These are assembled by Briggs in Milwaukee Wisconsin.  USA!!!

Offline CC-Coder

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Tom, not completely understanding all the technical jargon, but do you think your 3D printer / performance impeller might make a comeback with this new information?

http://www.improvingyourmokai.com/index.php/topic,928.msg14716.html#msg14716
🤦🏼‍♂️ Chuck 🤷🏻‍♂️

Offline Painlesstom

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I printed one too, but never got around to testing it. The stock impeller profile is really the best in this pump size and design. More power is what's needed.  \./8
Tom

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Offline happul3

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Is this the one you are looking at?  I marked it where 7 hp ends. 
...
we run our Mokai's at an rpm over 3600 which results in lost hp.  4.75 at 3600 and it looks like 2.5 hp at 4000. 

That is not how I read the chart. The line from ~4hp at 2000 to ~7hp at 4000 is marked "maximum horsepower" and that's the one I take as figure of merit. The line that shows decrease in HP to ~2.5 at 4000 must mean some sort of recommended use. It cannot be the actual maximum power output by the motor or we would not be able to operate stock v1 at 4000 rpms at all.

Also, the torque line on the same chart is even less ambiguous and consistent with my interpretation. I read ~12.35 N.m at 4000 rpms , which translates to 9.11 ft-lb and 6.94 hp (=9.11*4000/5252).


Offline happul3

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  Ever notice when the grate completely clogs the rpm is almost the same as when it is clear.  The motor is not under a huge load.  If it was there would be a significant rpm difference inside the water and outside the water. 

The reason for max rpms being the same with and without load (as in clogged intake or running motor wthout pump out of water) is presence of governor. That means that when running with less than full load at 4000 rpms, the motor produces only a fraction of 7 hp. Which brings one to the next logical question: how close the stock v1 is to being fully loaded? Or, in other words, what's the actual hp output? I asked that question before, but never got a good response.  I suppose that does not matter much considering that Tom's experiments with better impeller did not yield any significant improvement. If the motor is indeed under-loaded, it would probably require expanding an intake channel to fix that and that is close to rebuilding the hull itself...   

Anyhoo, going from 7hp @4000 rpms Subaru to  7.5hp @4000 rpms Animal just does not seem like something worth the trouble.   8 hp @ 5000 rpms may be a little more promising, but you'll need gearing to get to those horses (something like 1:1.2?). Seems like just upgrading head on EX21 would be a lot easier and yet give you a similar boost.


Offline Painlesstom

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Re: Es-Kape 1.0 upgrade to Briggs & Stratton Animal 206cc Kart Racking Engine
« Reply #10 on: October 08, 2019, 12:12:09 AM »
Yeah, without the governor in place my RPM's can get quite high with a clogged grate. Normal full throttle under load is 4380, but clog the grate or get something stuck in the impeller and that can jump up to 4600 no problem or more if I don't keep the throttle in check.

I predicted the animal would give an increase to 20-21 mph at around 4400-4500 rpm, compared to the 18 mph the stock EX21 is doing. But I'd be glad to be wrong and see it sing at 5000 rpm.

If you have any pump issues, Nick, my rebuild and oil lube conversion will handle the rpm you are after.  \./8
Tom

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Offline Hillbilly

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Re: Es-Kape 1.0 upgrade to Briggs & Stratton Animal 206cc Kart Racking Engine
« Reply #11 on: October 08, 2019, 09:22:03 AM »
You've started an exciting discussion here, Voipwell.  The hull design of the 1.0 seems to be better for speed than the older designs, just as the newer/old design was better than original.  The animal motor in the 1.0 hull may be just the ticket and you are just the guy to find out.  Hope you follow through and have have great success here.  Discussing numbers is fun but the way to find out is to do it. 

I run KX motors with no governor and my rpm's go way up with grate obstruction.

Looking forward to what you learn.  Thanks

Offline voipwell

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Re: Es-Kape 1.0 upgrade to Briggs & Stratton Animal 206cc Kart Racking Engine
« Reply #12 on: October 08, 2019, 11:54:41 AM »
For the subaru to put out 7 hp @ 4000 rpm it would be putting out the equivalent of about 5.5kw.  Look around what 5 kw generators are powered with.  Between 400cc and 700cc.  The ex21 is around 200cc?   

I remember seeing a video Tom did showing the 1.0 losing rpm over the first few minutes stating it was getting hot.  It was doing exactly what the chart indicates it would do.  Those two points that say"Continuous Output" that's all you get.  The maximum torque and output are theoretical.  You buy a generator that says 2200 watts peak,  1800 watts continuous.  Try to run the 2200 for more than a few seconds and it pops.  You are seeing maximum/peak/not sustainable and thinking you are getting that.  They are not rating small engines with hp ratings anymore.  HP is torque x 5252 / rpm.  The Maximum torque and hp are not sustainable only the continous output is.  Anything outside the blue is theoretical.  Inside the blue is what you build a boat around.

Offline happul3

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Re: Es-Kape 1.0 upgrade to Briggs & Stratton Animal 206cc Kart Racking Engine
« Reply #13 on: October 08, 2019, 01:29:54 PM »
Blue region is clearly identified as "recommended". The motor obviously can and does produce substantially more HPs than that. Do you really think that its actual power output drops to 2.5Hp at 3800 rpms and to 1 HP at 4000 rpms? Mine runs at slightly above 4000 rpms full throttle giving me 14 mph (yes, I am heavy) without any tweaks.  Obviously it takes far more than 1 or even 2.5 HP to do that. Whether one should or should not design boats sticking to "recommended" range of operation is not for me to say. Mokai clearly did not and, personally, I am glad that's the case.

If you still think that 7 hp line is "theoretical", you can look at it from a different perspective too. Why do you think the HP output peaks at 3400 rpms and drops so drastically above 3600 rpms? Internal losses, friction, etc.? That would make upgrading   EX21 head and to try and raise rpms above 4000 completely pointless. And yet we know that it actually helps, which means that HP output actually increases, not drops as one approaches 4000 rpms. So the line of interest on that chart is the one that goes to 7Hp/4000rpms point.


Offline Painlesstom

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Re: Es-Kape 1.0 upgrade to Briggs & Stratton Animal 206cc Kart Racking Engine
« Reply #14 on: October 08, 2019, 02:56:35 PM »
For the subaru to put out 7 hp @ 4000 rpm it would be putting out the equivalent of about 5.5kw.  Look around what 5 kw generators are powered with.  Between 400cc and 700cc.  The ex21 is around 200cc?   

I remember seeing a video Tom did showing the 1.0 losing rpm over the first few minutes stating it was getting hot.  It was doing exactly what the chart indicates it would do.  Those two points that say"Continuous Output" that's all you get.  The maximum torque and output are theoretical.  You buy a generator that says 2200 watts peak,  1800 watts continuous.  Try to run the 2200 for more than a few seconds and it pops.  You are seeing maximum/peak/not sustainable and thinking you are getting that.  They are not rating small engines with hp ratings anymore.  HP is torque x 5252 / rpm.  The Maximum torque and hp are not sustainable only the continous output is.  Anything outside the blue is theoretical.  Inside the blue is what you build a boat around.

My 5500kw generator has a 305cc Briggs, and my 1.0 losing rpm initially was due to the small plenum size and overheating. Once I opened it up, and ran my water cooled muffler and cold air intake my rpms remain constant from start of trip to finish.

The EX21 is 210cc. Adding the EX17 head boosted compression and increased power above 4000 rpm, the KX head also boosts compression as well as having larger ports and valves which is where it can make power at even higher rpm's. So charts aren't the golden rule; just a guide to go by in general.

Like Hillbilly said though, numbers are fun to discuss, but as the old saying goes, "the proof of the pudding is in the tasting". Get that Animal in there already! haha  :D
Tom

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