Ninja 250 Compressed Natural Gas Conversion

[nrninja]

My senior design team is entering a competition where the vehicle which runs a set distance (approximately 150 miles) using the least amount of money wins. Our budget doesn't allow for electric because we'd need a 12kWh pack which gets pretty damn expensive.

Our next best idea is to do a CNG conversion on a Ninja 250. We've already got an EX-250F and have talked to the guys at EcoTrons about helping out with a fuel injection system compatible with CNG. They seem to have something we can use so CNG is looking like a real possibility.

To the best of my knowledge CNG is roughly equivalent to a 120 octane rating. Based on this my team would need to go with high compression pistons from JE Pistons (http://www.jepistons.com/Catalogs/Po...inja_250r.aspx), and probably shave a few thousandths off the head to increase compression even more. We'd be looking at greater than 14:1 compression. We'd also need to beef up the other engine components to handle this.

Taking all of this into account, do you think the engine can handle these modifications? Is there a better small displacement engine platform for CNG conversion?

Anyone ever tried CNG? Or have information on how to do it?

[jkv45]

Interesting concept.

Why would you "need" to go with high compression pistons? I wouldn't think you would have to. If the Ninja is in good running order I would work on getting the CNG to meter properly and only after that would start disassembling the engine to make mods. Why do you want to increase the compression that much? The Ninja engine can easily take the amount of power increase you'd get from the higher compression.

A local Taxi company has been running it's old Chrysler cabs on Propane for decades. Have you considered both CNG and Propane? Propane has more energy than CNG (you'd need to carry less), but I'm really not very familiar with either as a fuel for IC engines.

[Lychee]

What kind of mileage would you expect from this conversion and what does CNG cost in your area? I read on some cng site that a normal mileage is about 50 per GGE. That would mean @ $2/GGE CNG would cost $6 to travel 150 miles.

There are hypermilers (@greenaero) who have got well over 130 mpg using aerodynamics, technique and final drive modifications. 130 miles @ $3.75 / gallon of gasoline would mean that 150 miles would be a little over $4.32. I think that is on a carbureted engine too.
Does my math sound about right?

Maybe if you did both the CNG conversion and the aerodynamic modifications you could get that number even lower.

[Racer x]

You will NEED to raise compression. And add timing. The engine will not run on 120 octane fuel otherwise. Trust me on that.

Get the JE 13.5 to one pistons. But DO NOT CUT THE HEAD
The valves are very close to the edge and cutting the head will give you problems. I would suggest taking 10 thous off the top of the block. The service limit on the head is 20 thou so half that will be fine. But remember lowering the head will advance cam timing. Not great for what you want. So you would need to adjust the cam timing with sprockets.
The engine will hold up fine but a clutch spring upgrade would not hurt.

I have done all of this and had no problems but on a 2008 engine. What year is your bike? If it is before 2007 you can't do anything because of the head shape.

[nrninja]

Originally Posted by Lychee

What kind of mileage would you expect from this conversion and what does CNG cost in your area? I read on some cng site that a normal mileage is about 50 per GGE. That would mean @ $2/GGE CNG would cost $6 to travel 150 miles.

There are hypermilers (@greenaero) who have got well over 130 mpg using aerodynamics, technique and final drive modifications. 130 miles @ $3.75 / gallon of gasoline would mean that 150 miles would be a little over $4.32. I think that is on a carbureted engine too.
Does my math sound about right?

Maybe if you did both the CNG conversion and the aerodynamic modifications you could get that number even lower.

Somewhere around 95mpg CNG should make our team competitive. Upwards of 95-100 mpg CNG would have us winning. We'd need close to 140-150 mpg gasoline to be competitive. The goal is around 0.02$/mile regardless of drive train.

We're planning on doing a custom frame as well as a completely enclosed composite stream liner.

Originally Posted by Racer x

You will NEED to raise compression. And add timing. The engine will not run on 120 octane fuel otherwise. Trust me on that.

Get the JE 13.5 to one pistons. But DO NOT CUT THE HEAD
The valves are very close to the edge and cutting the head will give you problems. I would suggest taking 10 thous off the top of the block. The service limit on the head is 20 thou so half that will be fine. But remember lowering the head will advance cam timing. Not great for what you want. So you would need to adjust the cam timing with sprockets.
The engine will hold up fine but a clutch spring upgrade would not hurt.

I have done all of this and had no problems but on a 2008 engine. What year is your bike? If it is before 2007 you can't do anything because of the head shape.

Thanks for the info about the head! Our current bike is an EX-250F (88-07). I can't remember the exact year. We're likely going to buy a spare engine from eBay to do the CNG conversion, so would an 08-2012 engine be a better choice?

Originally Posted by jkv45

Interesting concept.

Why would you "need" to go with high compression pistons? I wouldn't think you would have to. If the Ninja is in good running order I would work on getting the CNG to meter properly and only after that would start disassembling the engine to make mods. Why do you want to increase the compression that much? The Ninja engine can easily take the amount of power increase you'd get from the higher compression.

A local Taxi company has been running it's old Chrysler cabs on Propane for decades. Have you considered both CNG and Propane? Propane has more energy than CNG (you'd need to carry less), but I'm really not very familiar with either as a fuel for IC engines.

High compression ratio means a fuel with a higher octane rating must be used to prolong detonation and prevent engine knock.

Instead of starting with a high compression ratio and matching a fuel to work, we're starting with a high octane rating and matching a compression ratio to work. 14:1 is our current goal for CR, but not necessarily what we'll end up using.

[Racer x]

There is no better way to do it. Find the fuel then build around it. I am building my turbo bike around Q 16 from VP. With my nitrous bike I have tried all different types of fuel. And it has been a difficult thing to figure out. Because it is all trial and error. But if you start with the fuel than you know where to go tuning wise.

In my experience the new engine is better. Mainly because of the rocker arms.
But the first generation engines are also a little hard to find.

[Motofool]

Originally Posted by nrninja

My senior design team is entering a competition where the vehicle which runs a set distance (approximately 150 miles) using the least amount of money wins. Our budget doesn't allow for electric because we'd need a 12kWh pack which gets pretty damn expensive. ..............

Taking all of this into account, do you think the engine can handle these modifications? Is there a better small displacement engine platform for CNG conversion?

Anyone ever tried CNG? Or have information on how to do it?

You have probably read this article, David, but I use it to quote some things that may be limiting the relatively weak gasoline Ninja engine and its marginal cooling system:

http://en.wikipedia.org/wiki/Gas_engine

"Manufacturers of gas engines include Rolls-Royce with the Bergen-Engines AS, Kawasaki Heavy Industries, MTU Friedrichshafen, GE Jenbacher, Caterpillar Inc., Perkins Engines, MWM, Cummins, Wärtsilä, GE Energy Waukesha, Guascor Power, Deutz, MTU, MAN, Fairbanks Morse, Doosan, and Yanmar........Rolls-Royce with the Bergen Engines, Caterpillar and many other manufacturers base their products on a diesel engine block and crankshaft. GE Jenbacher are the sole company whose engines are designed and dedicated to gas alone.

A gas engine differs from a petrol engine in the way the fuel and air are mixed. A petrol engine uses a carburetor or fuel injection but a gas engine often uses a Venturi system to introduce gas into the air flow. Early gas engines used a three-valve system, with separate inlet valves for air and gas.

The weak point of a gas engine compared to a diesel engine is the exhaust valves, since the gas engine exhaust gases are much hotter for a given output, and this limits the power output. Thus a diesel engine from a given manufacturer will usually have a higher maximum output than the same engine block size in the gas engine version.

Some engines (air or water) have an added oil cooler.
Cooling is required to remove excessive heat, over heating can cause engine failure, usually from wear, cracking or warping."

There are commercial conversion kits:

http://www.popularmechanics.com/cars...to-natural-gas

http://www.cngunited.com/

http://propanecarbs.com/

http://www.propane-generators.com/

Your team will need to do an economic evaluation about increasing compression ratio or not, because the engine's parts, valves and bearings may stand higher loads for a couple of hours of operation at higher temperatures, but all that modification work could easily kill your budget and deadline.

The main killer of the energy of your fuel is the aerodynamic and rolling resistive forces, which as you know, grow quadratically with the speed.
I would focus on reducing those as much as possible within the rules of the competition, rather than risking budget and reliability by trying to increase the efficiency of an engine with little safety factors.

[Racer x]

If the engine exhaust temp exceeds 1300 deg the plug tips vanish. And the valves burn
Ask me how I know.

[Racer x]

Enclosed streamliner!!! Really. Is this for public roads? Do you have any experience on two wheels and no body movement? Have you thought about a fire system and egress time? I am very concerned with safety. Streamliners a very dangerous.

[quarterliter]

How big of a budget do you have? If you can afford a CBR 250R then buy one instead of modding the ninja. A FI singles will get better mileage than a carbed twin screamer engine. We can talk about how as rpm increases so does friction at a higher rate, but it is a better starting platform. Plus having only 1 cylinder to worry about makes everything a lot simpler.

Morale of the story buy a CBR 250 and sell the kawi

[jkv45]

Originally Posted by nrninja

Instead of starting with a high compression ratio and matching a fuel to work, we're starting with a high octane rating and matching a compression ratio to work. 14:1 is our current goal for CR, but not necessarily what we'll end up using.

I guess I still don't understand why you HAVE to have a higher compression ratio. Won't you get proper ignition with the standard ratio? In a regular gas engine you can run higher octane gas than required and you'll lose some power - but that's it. You won't be needing any additional power if you are going for mileage.

If you have the time and money, pick a better platform. As 1/4L noted, a Honda CBR250R single is a significantly better starting point for a mileage vehicle than a Ninja 250 twin for numerous reasons.

[nrninja]

Originally Posted by jkv45

I guess I still don't understand why you HAVE to have a higher compression ratio. Won't you get proper ignition with the standard ratio? In a regular gas engine you can run higher octane gas than required and you'll lose some power - but that's it. You won't be needing any additional power if you are going for mileage.

If you have the time and money, pick a better platform. As 1/4L noted, a Honda CBR250R single is a significantly better starting point for a mileage vehicle than a Ninja 250 twin for numerous reasons.

From the wikipedia page on Octane rating:
The compression ratio is directly related to power and to thermodynamic efficiency of an internal combustion engine (see Otto-cycle). Engines with higher compression ratios develop more area under the Otto-Cycle curve, thus they extract more energy from a given quantity of fuel.

Efficiency and CR are directly related, higher CR leads to higher efficiency, which leads to less energy used.

A CBR250R as our starting platform is an option, however we are required to build a vehicle which can maintain highway speeds and pass comfortably on the highway. This means speeds in excess of 70mph (70mph posted limit, a little extra for passing). The CBR250R is good for commuting, not for highway use. I owned a Ninja 250 for over a year and even that was scary on the highways. I rode it from my university up I-81 and east on I-66 numerous time. It can do highway speeds, but can't pass other vehicles while at 70-75mph easily.

As far as buying a CBR250R the used market around my university has them for upwards of $3000. We could buy one but it would put a serious dent in our budget. Why not use the Ninja 250 we already have, combined with an EFI kit from EcoTrons (we're in talks about a deal on the kit right now)?

We're going to have a decision matrix, then weight all of our critical values, and see which platform fits to those the best. If it ends up being a 100cc two-stroke that's what we'll use.

tl;dr: Still looking for base platforms suited to our project, while considering our budget and what we have readily available

Originally Posted by Racer x

Enclosed streamliner!!! Really. Is this for public roads? Do you have any experience on two wheels and no body movement? Have you thought about a fire system and egress time? I am very concerned with safety. Streamliners a very dangerous.

Yes, enclosed stream liner. It will give the most aerodynamic shape. It will be used on public roads. We're working on developing a standard for our egress time and fire suppression system. We're looking into a quick release for the stream liner which would allow it to pop off the bike in about a second.

I'm more worried about an impact puncturing the tank. If that were to happen egress time and fire suppression wouldn't matter. The rider (me) would be dead.

Thanks for the heads up about the valves and newer engines!

[Racer x]

Best of luck on this. I am looking forward to your progress. Feel free to contact me if you need anything. Through my land speed racing I have contacts with the top builders in the world. And people that push streamliners to 300 + mph.

[Joshorilla]

150 miles with the least amount of money, considered pushing it?

I think you've ruled out electric too early, with three boat batteries you'd do it easily if you get the right gearing, increase tyre pressure and do some aero mods.

[nrninja]

Originally Posted by Joshorilla

150 miles with the least amount of money, considered pushing it?

If you know anyone that can push a motorcycle at 70mph, let me know.

Originally Posted by Racer x

Best of luck on this. I am looking forward to your progress. Feel free to contact me if you need anything. Through my land speed racing I have contacts with the top builders in the world. And people that push streamliners to 300 + mph.

Thanks! I'll try to keep this thread updated with our progress or start a new one if we don't do CNG.

[jkv45]

Originally Posted by nrninja

Efficiency and CR are directly related, higher CR leads to higher efficiency, which leads to less energy used.

A CBR250R as our starting platform is an option, however we are required to build a vehicle which can maintain highway speeds and pass comfortably on the highway. This means speeds in excess of 70mph (70mph posted limit, a little extra for passing). The CBR250R is good for commuting, not for highway use. I owned a Ninja 250 for over a year and even that was scary on the highways. I rode it from my university up I-81 and east on I-66 numerous time. It can do highway speeds, but can't pass other vehicles while at 70-75mph easily.

As far as buying a CBR250R the used market around my university has them for upwards of $3000. We could buy one but it would put a serious dent in our budget. Why not use the Ninja 250 we already have, combined with an EFI kit from EcoTrons (we're in talks about a deal on the kit right now)?

We're going to have a decision matrix, then weight all of our critical values, and see which platform fits to those the best. If it ends up being a 100cc two-stroke that's what we'll use.

tl;dr: Still looking for base platforms suited to our project, while considering our budget and what we have readily available

Thanks, but I understand what compression ratio does, just not why you need to raise it for this use. If you really want maximum efficiency, the Ninja is a step backward. 2-cyl...strike...tuned for peak power near redline...strike...2 of everything...strike... - higher compression ratio isn't going to offset those.

With all of the trouble you will be going through to build a streamliner, getting the best basic platform makes more sense.

Do you really need to go 70+ mph in the competition? The CBR will do it, but not efficiently - but neither will the Ninja. There's a CBR250R rider that has gone from Florida to the Arctic and back (http://www.cbr250.net/forum/ride-rep...rn-states.html). Once you have it streamlined those speeds will be much easier to obtain, but I wouldn't go there if you want efficiency.

Study the info at www.craigvetter.com in the fuel economy section. Look at the competitions from the 80s where they were in the 400+ MPG range on gas with a tiny 175cc single streamliner. The newer challenges have different rules, and are more of a high-speed highway cruise competition. The Ninja 250s are in the 100+ MPG range, but the Diesel has been the clear winner.

So have you considered Propane? Diesel? Or maybe E85? I agree about the electric - I don't think you can go 150 miles at this point with a reasonable investment - especially if you need highway speeds for any length of time.

EDIT: Because Honda is introducing a new CBR300R, there should be more 250s on the market at lower prices shortly.

[Racer x]

Back to the stream liner part. A catastrophic tank failure is a concern. But from what I have seen. Its the small electrical fire you need to worry about.
When a streamliner goes through tech inspection. It takes three inspectors to sign off. There must be a speration between the engine Compartment and the pilot/ rider area. They inspectors look at the fire wall with flashlights. Not even light from a tiny hole is allowed. The other fear is carbon monoxide or poisonous gasses entering the pilot compartment. This would lead to dizziness. And that is the worst thing on two wheels.

[jkv45]

If there's any stopping involved, a full streamliner would be a pain because you'd need some type of outriggers. You'd be a lot better going with partial stramlining like the Vetter Challenge bikes so you can put your feet down, exit without assistance, and not worry about dangers of a completely enclosed cockpit.

EDIT - With a partial streamliner like the Vetter bikes, you could put your fuel cylinder inside the large tail section, behind a bulkhead, for ease of mounting and safety.

[nrninja]

Originally Posted by jkv45

Thanks, but I understand what compression ratio does, just not why you need to raise it for this use. If you really want maximum efficiency, the Ninja is a step backward. 2-cyl...strike...tuned for peak power near redline...strike...2 of everything...strike... - higher compression ratio isn't going to offset those.

We'd want to burn the fuel (from whatever source) as efficiently as possible. Higher octane requires a higher CR to burn efficiently.

If nothing other than keeping costs low, we've already got a Ninja 250.

Originally Posted by jkv45

With all of the trouble you will be going through to build a streamliner, getting the best basic platform makes more sense.

Agreed. But again, budgetary concerns.

Originally Posted by jkv45

Do you really need to go 70+ mph in the competition? The CBR will do it, but not efficiently - but neither will the Ninja. There's a CBR250R rider that has gone from Florida to the Arctic and back (http://www.cbr250.net/forum/ride-rep...rn-states.html). Once you have it streamlined those speeds will be much easier to obtain, but I wouldn't go there if you want efficiency.

Sustained speeds of 70mph are a requirement of the competition.

Originally Posted by jkv45

Study the info at www.craigvetter.com in the fuel economy section. Look at the competitions from the 80s where they were in the 400+ MPG range on gas with a tiny 175cc single streamliner. The newer challenges have different rules, and are more of a high-speed highway cruise competition. The Ninja 250s are in the 100+ MPG range, but the Diesel has been the clear winner.

The competition we go to is actually the Vetter Challenge. I've met and talked to Vetter at length. He is not an engineer and does not necessarily know what he's talking about. He does have some good ideas, but I try to take them with a grain of salt.

The 400+ mpg was from a time when the challenge expected 55mph highway speeds. The rules for the challenge were significantly different.

Originally Posted by jkv45

So have you considered Propane? Diesel? Or maybe E85? I agree about the electric - I don't think you can go 150 miles at this point with a reasonable investment - especially if you need highway speeds for any length of time.

Does propane have any advantages over CNG?

Diesel is a no go. Fred Haye's diesel has won because of all the R&D Haye's was able to do with his company. He has millions invested into creating a diesel which can rev up to almost the same RPMs as a conventional bike. He has never sold any of his bikes to consumers, and last I heard does not plan to.

We hadn't considered E85... We'll need to look into it.

Originally Posted by Racer x

Back to the stream liner part. A catastrophic tank failure is a concern. But from what I have seen. Its the small electrical fire you need to worry about.
When a streamliner goes through tech inspection. It takes three inspectors to sign off. There must be a speration between the engine Compartment and the pilot/ rider area. They inspectors look at the fire wall with flashlights. Not even light from a tiny hole is allowed. The other fear is carbon monoxide or poisonous gasses entering the pilot compartment. This would lead to dizziness. And that is the worst thing on two wheels.

I'll bring up the concerns about gases and firewalls to the team. Thanks again!

Originally Posted by jkv45

If there's any stopping involved, a full streamliner would be a pain because you'd need some type of outriggers. You'd be a lot better going with partial stramlining like the Vetter Challenge bikes so you can put your feet down, exit without assistance, and not worry about dangers of a completely enclosed cockpit.

EDIT - With a partial streamliner like the Vetter bikes, you could put your fuel cylinder inside the large tail section, behind a bulkhead, for ease of mounting and safety.

The plan was to have the bottom of the stream liner near the rider open.

EDIT: The bulkheads are (typically) used as storage space for the grocery bag requirements of the Vetter Challenge. Not to say we couldn't put a fuel tank there, but the groceries need to be carried as well.

[choneofakind]

You likely already know this from talking to Craig, but you'll be just fine at sustained 70+ with streamlining and tall gearing.

Paging @greenaero for more reference for you.
He's a regular with Craig. He's running something like 15/39 gearing with streamline fairings without issue at 70+ all day long. I know that doesn't help you with the fuel decision, but that should help with gearing choice once you need to decide on that.

[jkv45]

Originally Posted by nrninja

We'd want to burn the fuel (from whatever source) as efficiently as possible. Higher octane requires a higher CR to burn efficiently.

Sustained speeds of 70mph are a requirement of the competition.

The competition we go to is actually the Vetter Challenge. I've met and talked to Vetter at length. He is not an engineer and does not necessarily know what he's talking about. He does have some good ideas, but I try to take them with a grain of salt.

The 400+ mpg was from a time when the challenge expected 55mph highway speeds. The rules for the challenge were significantly different.

Does propane have any advantages over CNG?

EDIT: The bulkheads are (typically) used as storage space for the grocery bag requirements of the Vetter Challenge. Not to say we couldn't put a fuel tank there, but the groceries need to be carried as well.

Ah...the Vetter Challenge - why didn't you say so?

That changes things...

As far as a higher octane fuel needing higher compression to burn efficiently - I don't know about that. You will make more power with higher octane fuel only if you have a compression ratio that requires it, but that's not to say the fuel doesn't burn at lower compression ratios. I'm not sure that upping the compression ratio because CNG has a higher octane rating will produce significant increases in power or MPG (especially at smaller throttle openings and lower RPMs).

You'd have to research CNG to see if compression is a factor for complete combustion or not. Propane is similar, but has more energy so you'd use less. But that's just from simple research - there may be more to it.

If you want to carry the bags for the Challenge, you would have a hard time fitting a cylinder of any decent size also. Propane might help that situation. E85 is less expensive, but uses more (lower cost but lower MPG) - not a problem with the stock Ninja tank. It does support higher compression than regular gas, but I don't know if you could take advantage of that significantly.

[greenaero]

Interesting discussion! I don't know much about CNG but I would think if it was cheap and easy more people would be going to it. To me it sounds like a lot of work and inve$tment . Good luck with it.
With the progress Alan Smith and I have made with our gasoline powered Ninjas we should be breaking the 150 mpg barrier soon. Reducing aerodynamic drag and raising the gearing are fairly simple, cheap and very effective. Be careful with a fully enclosing the rider as fully enclosed streamliners are very easily blown over. Be sure to include some pass-through space around the rider for side winds and greater ease in getting on and off the bike. Also make sure your cooling airflow is adequate as you build your bodywork.
Its good to hear from the Virginia Tech team, please give my best regards to Dr. Goff and the rest of the team.
all the best, Vic

[choneofakind]

From a thermodynamics stand point, higher CR yields better efficiency. He's right.

[jkv45]

Originally Posted by choneofakind

From a thermodynamics stand point, higher CR yields better efficiency. He's right.

I agree with that part, I just don't think you would gain enough to make it worth it.

If you were looking for maximum efficiency, you are way ahead using a lower-revving single cylinder engine like the CBR250R than a high revving twin like the Ninja's - even if it had high compression.

Because you are looking for maximum MPG, not power, the efficiency gains from the increased compression wouldn't be significant.

That's my thought, but anyone is free to disagree.

[choneofakind]

Sure, but streamlining and gearing changes negates the rev-factor. Once you remove that huge wind resistance by streamlining, you can run mega tall gearing, like 15/39 and cruise 70 at 6000 rpm all day long. Wind resistance (after rider input) is definitely the biggest factor in how much power you need.

[jkv45]

Originally Posted by choneofakind

Sure, but streamlining and gearing changes negates the rev-factor. Once you remove that huge wind resistance by streamlining, you can run mega tall gearing, like 15/39 and cruise 70 at 6000 rpm all day long. Wind resistance (after rider input) is definitely the biggest factor in how much power you need.

Don't get me wrong - the Ninja's engine is an overachiever, but it's designed for maximum power near redline and that's where it's most efficient. Everything is biased that direction - valve size, cam timing, carb size, intake and exhaust port size, etc. Trying to get it to be as efficient as a single cylinder of the same displacement when running at 1/2 its peak RPM isn't going to happen. The cruise RPM you listed (6000) is much closer to the torque peak of a CBR (7100) than an EX (9900) engine. Everything about the CBR is much better suited for high efficiency lower-RPM cruising.



The Ninja has enjoyed much high-MPG (140+) success in the hands of Vic and Alan, but the overall design of the engine is still the limiting factor compared to a lower-revving single of the same displacement.

[choneofakind]

You could play around with the valve timing in order to move the most volumetric ally efficient rpm lower. I get what you're saying with the volumetric efficiency, but i still get my best best mileage if I cruise at 7k or less.

If they have a ninja 250 engine, I'm sure it wl be more than up to the task. No need to scrap it already for a thumper.

[quarterliter]

Think of it this way. They are probably going to need to buy the ecotron kit and that is quite expensive if I remember correctly. Also you have a bike you could sell the ninja to buy the CBR so in the big picture you could probably scrap $2000 together from the past bike stuff to put towards a CBR 250 that comes with FI and tuned for a lower rpm. What type of mileage can you get when using propane or CNG? How much worse than gasoline? You may be able to do this on gasoline and simplify the whole process

[jkv45]

Originally Posted by choneofakind

You could play around with the valve timing in order to move the most volumetric ally efficient rpm lower. I get what you're saying with the volumetric efficiency, but i still get my best best mileage if I cruise at 7k or less.

If they have a ninja 250 engine, I'm sure it wl be more than up to the task. No need to scrap it already for a thumper.

That depends if you are trying to win the competition or just compete with the others that are using the same platform.

[Motofool]

Originally Posted by quarterliter

.........You may be able to do this on gasoline and simplify the whole process

I agree with you; however, it seems that the OP will not deviate from his original plan.

They may not know much about the practical aspects of an engine attached to a frame and two wheels rolling over a public road (a Ninjette), but they have been swimming in deep studies about theoretical engines, thermodynamic cycles and fuel efficiency.

http://en.wikipedia.org/wiki/Fuel_ef...ontent_of_fuel

The point of their project is to put all that knowledge into a practical application (limited by certain rules) using the minimum mass of fuel possible.

Basically, all we can do is answering any practical question about the Ninja 250 that they may have and wishing his team good luck and success in their project.

The ideas and plans of this particular team may be spot on or way off, but only results will tell the truth.

If they bother to report back to this forum, we may be able to learn a couple of new technical things about our Ninjettes' from their experiment.

[Racer x]

The 250 ninja engine has two personality's. Below 7500 rpm it could be very economical to operate and make15-20 HP. Eliminating the counter shaft and rebalancing the motor then corking the intake and making a huge exhaust could work. It would be really cool to see and give the 250 ninjs even more respect that it deserves.

[bruce71198]

I used to work for a company that designed fuel injection systems for propane and CNG. I am not an engineer but worked as a technician in the dyno room so I have some hands on knowledge of what your trying to do. Some of the projects we developed; My 1996 Dodge Ram 1500 using CNG as fuel, several tubo diesel engines converted to spark ignition and run on CNG (you CAN NOT get this stuff to detonate or preignite), a CNG/electric hybrid Plymouth Neon, Gruman LLV postal vehicle powered with CNG as well as many municipal fleet vehicle applications. That was all CNG. We did many more with propane as well.
Things to take into consideration;1- You need compression to extract the BTU potential of this fuel, other wise you will be down on power, about 15% compared to gasoline. 2- CNG doesnt like to atomize with air, it seperates out and travels around the intake tract in bubbles. 3- its hard to store any quantity to match the same gasoline volume. You will need to compress it upwards of 3500 PSI. 4-you will need special CNG injectors, we typically used 3 injectors in a manifild that then ran to a shower head style nozzle and injected befor the throttle blades. Any gasoline control unit that you can lap top manipulate should work but CNG is far different than gasoline when it comes to delivery.
Sounds like a fun project. I look forward to the end results

[jkv45]

Originally Posted by bruce71198

I used to work for a company that designed fuel injection systems for propane and CNG. I am not an engineer but worked as a technician in the dyno room so I have some hands on knowledge of what your trying to do. Some of the projects we developed; My 1996 Dodge Ram 1500 using CNG as fuel, several tubo diesel engines converted to spark ignition and run on CNG (you CAN NOT get this stuff to detonate or preignite), a CNG/electric hybrid Plymouth Neon, Gruman LLV postal vehicle powered with CNG as well as many municipal fleet vehicle applications. That was all CNG. We did many more with propane as well.
Things to take into consideration;1- You need compression to extract the BTU potential of this fuel, other wise you will be down on power, about 15% compared to gasoline. 2- CNG doesnt like to atomize with air, it seperates out and travels around the intake tract in bubbles. 3- its hard to store any quantity to match the same gasoline volume. You will need to compress it upwards of 3500 PSI. 4-you will need special CNG injectors, we typically used 3 injectors in a manifild that then ran to a shower head style nozzle and injected befor the throttle blades. Any gasoline control unit that you can lap top manipulate should work but CNG is far different than gasoline when it comes to delivery.
Sounds like a fun project. I look forward to the end results

Do you think going to CNG or Propane (which would you recommend?) would be a good choice for a cost-per-mile competition?

In my limited research it didn't look like either would give the team an edge in cost-per-mile over gas. E85 didn't look like an advantage either, as the % of cost decrease didn't offset the average loss in mileage over regular gas - so there wasn't an advantage there.

I know you can get more peak power with increased compression in E85 and CNG/Propane applications, but do you think that an increase in peak power will translate into increased economy at a much lower RPM and a very small throttle opening?

I didn't think so, but I'm not positive...

[bruce71198]

It looks like they want to travel 150 miles as cheap as possible. Seing as though you cant measure a gallon of CNG and compare it to a gallon of gasoline you will have to do it as a cost of fuel per mile. I do think that you can travel one mile on CNG cheaper than a mile on gasoline.

[bruce71198]

Sorry Jay, I just reread your post and realized I didn't address your question on fuel preferance. CNG would be my fuel of choice as long as you have a source to get it. Propane has cold weather issues that can limit its use.

[Motofool]

Originally Posted by Racer x

...........It would be really cool to see and give the 250 ninja even more respect that it deserves.

Eric,

Could you explain what you have done to increased the compression ratio of your high performance engines and at what point you have needed to use gasoline of higher octane (with or without ethanol)?

Yes, I have read your post #4 above, but I am curious about the whole practical process and the types of fuel that you have used to reach your speed records.

Have you done any related work in pre-gen engines?

[Racer x]

Sure. And I don't mean to thread jack.

first I cut the top off the block. Just ,.010 th. About half the service limit of the head. This is to raise the compression before I could get pistons. I have to use the fuel from the track. The lowest octane was 100. So 11.6 to 1 stock and the cut block with seven deg of timing advance from a1988-94 CDI unit made ,30hp on stock carbs.

Then JE came out with pistons. And I bought the BRT ignition. The max compression I have run is ,13.5 with the cut block. I had to shim the spark plug with that and ran ,115 octane and timing up to 43 deg. That made 34 HP and pushed the bike to 112 mph. Best all motor I have. Since then its been nitrous and 12.5to1 with CR carbs and a 2mm over bore. Most of my effort has gone into the body work.
.

[bruce71198]

Originally Posted by Racer x

Sure. And I don't mean to thread jack.

first I cut the top off the block. Just ,.010 th. About half the service limit of the head. This is to raise the compression before I could get pistons. I have to use the fuel from the track. The lowest octane was 100. So 11.6 to 1 stock and the cut block with seven deg of timing advance from a1988-94 CDI unit made ,30hp on stock carbs.

Then JE came out with pistons. And I bought the BRT ignition. The max compression I have run is ,13.5 with the cut block. I had to shim the spark plug with that and ran ,115 octane and timing up to 43 deg. That made 34 HP and pushed the bike to 112 mph. Best all motor I have. Since then its been nitrous and 12.5to1 with CR carbs and a 2mm over bore. Most of my effort has gone into the body work.
.

Racerx, you have officially derailed this thread. But thats ok. I need some info on the deck height your running. When you took .010" off the deck was that a pre gen? It seems my 08 has .032" piston to deck clearance without the head gasket. My pre gen has .039". .010" seems to be cutting it a little close on the 08.

[Motofool]

Originally Posted by Racer x

Sure...........first I cut the top off the block. Just ,.010 th.......Since then its been nitrous and 12.5 to 1 with CR carbs..........

Thanks, Eric !!!



I don't believe that we are thread jacking, the OP can use all this good info.

1) When you talk about cutting 0.254 mm off of the block, do you refer to the top of the cylinders or the top of the crankcase (area over which the cylinders seat)?

2) Why did you need to reduce the compression ratio when using nitro?

[Racer x]

I only work with 2008 engines

I had the machinist mill the cylinder block top.

I reduce compression for nitrous because of the sharp points on top the 13 to 1 pistons.

Sorry about the thread jack. Maybe ask any questions in this thread. http://www.ninjette.org/forums/showthread.php?t=89190