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Discussion Starter · #1 ·
http://www.envirofit.org/files/publications/SAE%20SETC%20Design%20of%20a%20Direct%20Injection%20Retrofit%20Kit%20for%20Small.pdf

Good article for retrofit of DI system on small two-stroke motorcycle motor.
 

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Once Doo drops direct injection on us 4 strokes will have no advantages. Unless some people like more weight. Even todays E-Tecs have better mileage, less maintenance, less oil used, lighter weight, and higher power than 4 strokes. 4 strokes are nearly at their potential limit already. 2 strokes are just starting their evolution.
 

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Discussion Starter · #3 ·
I agree, I've been saying this for a year on this site and everyone just continues to say that 2-strokes are doomed. The only issue is going to be with the compressor. That can add some substantial weight. However I'm confident they'll find a way around that issue.
 

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I briefly read over the article. It is very interesting. The problem here is:

A) It still burns oil.
B) I feel this is a bigger issue, and that is mass production and calibration. DI is a very high pressure system. I do not think we yet have the injector or compressor technology available to bring this to mass production in an efficient way.
 

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What would be different then a DI on a sled over that on a Seadoo like I have?
 

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Just liek evenrudes etechs they put out lower imsions then 4 strokes but they still burn expoensive oil so thats the down side, it dosnt cost that much more but it is a bit more. i know when we had our optimax boat motor a di it was awsome on gas but oil was expensive, we spend about 150 in gas for the weekend at the lake so a little bit here and there helps.
 

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Originally posted by MonsterJay
[br]Once Doo drops direct injection on us 4 strokes will have no advantages. Unless some people like more weight. Even todays E-Tecs have better mileage, less maintenance, less oil used, lighter weight, and higher power than 4 strokes. 4 strokes are nearly at their potential limit already. 2 strokes are just starting their evolution.
I can buy that 2 strokes are still evolving and have potential, but how can you say that 4 strokes are nearly at their potential limit?

Reminds me of a motorcycle magazine from the 80's with a test of the yamaha fz 750 (or was it gsxr 750?) where the tester states that he believes that sport motorcycles have reached their performance limits, and simply couldnt get any faster.
 

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The E-Tecs burn oil but they burn less oil than what youd have to change on the 4 strokes. I believe 2 strokes have more room to grow than 4 strokes. We will see DI sleds from Cat, Doo, and Polaris within the next 3-4 yrs. At least by 2012 which is the next big emission year.
 

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Originally posted by MonsterJay
[br]The E-Tecs burn oil but they burn less oil than what youd have to change on the 4 strokes. I believe 2 strokes have more room to grow than 4 strokes. We will see DI sleds from Cat, Doo, and Polaris within the next 3-4 yrs. At least by 2012 which is the next big emission year.
What do you mean by "burn less oild that what youd have to change on 4 strokes"? I'm a little confused. Do you mean they only burn the amount of oil you'd have to change in a 4-stroke over that period of time from oil change to oil change?
 

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Discussion Starter · #11 ·
Originally posted by erick
[br]B) I feel this is a bigger issue, and that is mass production and calibration. DI is a very high pressure system. I do not think we yet have the injector or compressor technology available to bring this to mass production in an efficient way.
Okay, I understand your concerns here. I believe however that they do have the injector technology. SeaDoo runs an Orbital fuel direct injection system on one of their two stroke jetskis. But, unlike the system in the article, the Orbital system is a low pressure system. However this system has limitations. For instance according to the Orbital website, this technology is not yet ready for engines over 500 cc. So they are on the right track.
 

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Originally posted by Triple650Indy
[br]
Originally posted by erick
[br]B) I feel this is a bigger issue, and that is mass production and calibration. DI is a very high pressure system. I do not think we yet have the injector or compressor technology available to bring this to mass production in an efficient way.
Okay, I understand your concerns here. I believe however that they do have the injector technology. SeaDoo runs an Orbital fuel direct injection system on one of their two stroke jetskis. But, unlike the system in the article, the Orbital system is a low pressure system. However this system has limitations. For instance according to the Orbital website, this technology is not yet ready for engines over 500 cc. So they are on the right track.
Wait now Im confused how can the tech not be ready for over 500 cc if the RXDI Seadoo is a 951cc engine?
 

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Discussion Starter · #14 ·
Orbital has that information posted on their website. Unless they mean for ovver 500 cc of displacement per cylinder. That sounds more likely.
 

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Discussion Starter · #15 ·
Originally posted by MonsterJay
[br]I think its because the new tech in that article is for retrofitting to older engines. If its built from the ground up to be DI then it can be applied to any 2 stroke.
The system in the article is not an Orbital system. It is an independent government study.
 

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Originally posted by MonsterJay
[br]Once Doo drops direct injection on us 4 strokes will have no advantages. Unless some people like more weight. Even todays E-Tecs have better mileage, less maintenance, less oil used, lighter weight, and higher power than 4 strokes. 4 strokes are nearly at their potential limit already. 2 strokes are just starting their evolution.
Doo has been working with 2S technology on snow for 40+ years and only in the last 8 to 10 have realy started to push the envelope of the 2S motors. On the other hand 4S technolygoy on snow was developed and died back in the 70's because it could not be done. Look at the strides over the last four years. AMASING developments for laughing about it only 6 or 7 years ago. Good things take time. It will come out to surpise all of us or it may take the same trail of doom as it did back in the 70's but my guess is that with the big 4 all working with there enginering department to develope 4S tech, even Doo, that its not at the limit, its going to push the limits.
 

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Originally posted by Triple650Indy
[br]Orbital has that information posted on their website. Unless they mean for ovver 500 cc of displacement per cylinder. That sounds more likely.
Ok that makes sense. Do you have the link to the website?
 

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To me it seems the Ficht system would be better than the Orbital system. The reasons they did not use it in the study in the article is because of the power draw on a small hp engine, and the fact that it was a retrofit. In a new production snowmobile engine, niether of these factors would be problems.

Also, I belive the injector technology is available. I do not think they would be much different than diesel injectors.
 

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Originally posted by MonsterJay
[br]^^^^^^^^^^^^^Exactly. So you dont save any money with a 4 stroke. You have to buy more oil and an added oil filter every year.

I read in the triple thread that one 75 HP e-tec engine was using oil at a ratio of 100:1. That is 1 gallon of oil for every 100 gallons of gas. That seems like considerably more than what you say. That's only twice as good as my carburated 600cc, 120 HP two stroke snowmobile engine considering I used two quarts of oil last year every 25 gallons of gas (which it was). Now don't get me wrong, half the oil consumption would be awesome but it's no where near what you say.
 

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Discussion Starter · #20 ·
http://www.orbeng.com.au/orbital/directinjection/dioverview.htm

Yes, I reread the site and it is 500cc per cylinder.
 
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