9.9hp to 15hp just by changing carburators

[cenzo]

Is this easy, and where to find 15hp carb., plus literature on installation process.

 

[JB]

Re: 9.9hp to 15hp just by changing carburators

It doesn't convert, Cenzo. That is a widespread myth about nearly every make of 9.9 on the market.

 

[trog100]

Re: 9.9hp to 15hp just by changing carburators

it might be a "myth" but there is a basis of logic behind it.. <br /><br />the specs on a 9.9 and 15 engines are identical in every respect except for the power rating..<br /><br />the specs on a 20 and 30 are identical and so on up.. i cant help but feel that to fill out their range and save money by not making too many engines the manufacturers made two basically identical but rebadged engines fit two places in the power line up..<br /><br />take the 9.9 and the 15.<br /><br />the capacity is exactly the same.. <br /><br />the weight is exactly the same..<br /><br />in fact every single spec is the same.. except the claimed power output <br /><br />the same applies to the 20 and 30.. same weight same capacity as each other.. the next pair up follow the same pattern<br /><br />i think they are in essence the same engines.. the power difference probably isnt as great as claimed either.. so it probably isnt worth doing the conversion.. but it must be possible.. i dont think its a myth.. and looking at the parts list the carb does seem the only difference between the two engines..<br /><br />check the range right up and u will find one engine filling two places in the line up.. it does make a weird kinda sense when u think about it..<br /><br />its the identical weight and capacity on each pair of engines as the horse power goes up the range that are claimed to differ in horse power by 50% that convinces me that one is simply a crippled version of the other.. a smaller carb being the easiest way of playing this trick..<br /><br />basically u have a nice wide range of engines and only have to make half as many.. he he <br /><br />quite clever really..<br /><br />mercruiser played a similar trick when they first stopped making the 2.5 litre inboard engine.. to fill the missing 115 hp gap this would have left in the range they downgraded the 3.0L litre engine and called it the 115 bottom of the range engine.. the original 3.0L 135hp engine got called a 3.0lx and remained rated at 135 hp.. it was a fake downgrade thow.. and a simple trick to make one engine less and make the next one up fill its place.. in truth the so called 3.0L litre 115hp engine put out pretty much the same hp as the other one..<br /><br />when u sell engines by hp rating and need a nice full hp range.. there is more than one way to skin a cat.. the easiest and cheapest way is to make one engine fill two slots.. he he <br /><br />trog100

 

[roscoe]

Re: 9.9hp to 15hp just by changing carburators

The myth is that is can be done simply and cheaply by just changing the carb or a jet.<br /><br />Sure they share many common parts, but there are several that are not.<br /><br />Several or all the following, and more, come into play. <br />Exhaust porting / tuning, timing, rpm, intakes, carb, and so on.<br /><br />If it was a cheap and simple switch, we would all be buying the small motor of a series, and making the cheap conversion. Its not like the insides of these motors are top secret. We have all the parts and plenty of motors to examine.

 

[JB]

Re: 9.9hp to 15hp just by changing carburators

What you say is logical, Trog, but spec sheets do not include the factors mentioned by Roscoe.<br /><br />Anyone who has spent time and money increasing the output of engines would be thrilled to find a way to get a 50% increase in output by merely changing one part.

 

[Realgun]

Re: 9.9hp to 15hp just by changing carburators

JB when I was overclocking processors a small change in the motherboard could get you to a faster porcessor from a slower 1. But usually you had to cool the new processor better ie a bigger heat sink. So all in all it was worth it.<br /><br />300Mhz celeron was $100 and the 450 Celeron was $300.<br />So an extra 50 dollar fan was really worth it provided the Processor could handle the speed and 99% did with ease.<br /><br />Only problem now is on say an Etec 90 and a 115 what are the real differences? Only 1 I see is that the RPM range is upped 500rpm!<br /><br />So electronically and mechanically they are identical but I bet the 90 will not rev higher than 5500 (its mfg limit) but the 115 will rev to 6000 (its limit). <br /><br />All I need to know is what chip to change and how much! <br /><br />My guess on the Force 9.9 and 15 is there is a porting issue as well as a carb issue. Can't be to hard to figure out when you "know what they did." Only issue is how are you going to get the parts and how much it will cost you.

 

[JB]

Re: 9.9hp to 15hp just by changing carburators

Well, you could probably get 15hp from that 9.9 by adding a supercharger, too, but that is not a carburetor.<br /><br />Bombardier is not going to publish the differences between engines rated at different hp on the same basic block. That would be stupid. The differences are there.<br /><br />The 90 and 115 E-Tec are neither mechanically nor electronically (firmware) identical.

 

[trog100]

Re: 9.9hp to 15hp just by changing carburators

that computer cpu thing goes deeper than that.. a certain type all comes off the same line.. they simply badge and set them to fill market requirements.. if the market wants more lower speed ones they badge more lower speed ones.. a 100 dollar one really is the same as 400 dolllar one.. they are simply speed set in the factory..<br /><br />deliberately limitting the amount of "full-speed" ones.. keeps the price right up.. <br /><br />not a thing that joe public is sposed to know thow.. to be able to make one basic item that with a few tweaks and different badges fills a whole market range is a modern manufacturers dream..<br /><br />the thing about one basic engine filling two spots in the line up makes sense.. it not a question of tuning an engine for more power than its intended to give.. its more a question of de-tuning a 15 hp engine into a 9.9 by fitting the smaller carb and perhaps altering the porting.. <br /><br />the whole point of this exercise is to keep the number of parts that need to be produced down to a minimum.. the two engines weighing exactly the same.. with the same physical dimentions and having the same cylinder capacity is what gives the game away.. it really would be very easy simply to fit a smaller carb to what is in essence is a 15 and rebadge it as a 9.9..<br /><br />if the name of the game is to keep the part count down.. why not.. u aint gonna change any more parts than u have to..<br /><br />two engines that differ in power output by 50% should not have to be the same capacity.. weight and size.. if they really were two different engines.. the less powerfull one should weigh less and have less capacity for things to make sense.. <br /><br />turning a real 9.9 into a 15.. might be hard.. but if it really is a crippled 15.. all it needs is to be uncrippled.. fitting a bigger carb would probaly take it most if not all the way..<br /><br />the 9.9 carb really is a puny little thing for a 250cc engine and about as basic in its design as u could imagine.. bin playing with an old 9.9 in a tub over the last couple of days.. seeing if it runs okay.. took the carb to bits to check it out.. it does seem a powerfull high revving little brute for its claimed power output compared to my newer 5hp mercury kicker engine..<br /><br />apart from perhaps the cheaper carb.. i cant see any reason other than marketing that a 15 should cost more either than a 9.9.. the marketing ploy of course being that if the two engines did truely reflect the cost of manufacture.. no one would buy the less powerfull 9.9.. follow this principle right up the power range and we would only have half as many power options available to us.. <br /><br />and to take the computer chip instance further.. the cheaper slower ones can sometimes cost more to make than the expensive faster ones.. why.. cos they take a finished faster one and do "extra" things to it to cripple it (like remove half its memory cache) and make it into a real slower one as opposed to a fake one.. he he<br /><br />and with engines to come.. or it will need to alter power outputs is a different engine management chip.. there is already a black market in go-faster chips for modern perfomance cars..<br /><br />basically to play the 9.9 or 15 trick with a newly designed ecu controled engine all it would need is a different management chip.. back then all it needed was a smaller carb..???<br /><br />its a funny old world and as time passes i recon its gonna get funnier.. he he<br /><br />trog100

 

[chrysler_joe]

Re: 9.9hp to 15hp just by changing carburators

If you are talking about a Force 9.9 1987-1989 then all you need do is install a larger jet and increase the reed valve opening.If your interested e-mail me and I will try to find the book with the spec. ffjoe@rogers.com

 

[cenzo]

Re: 9.9hp to 15hp just by changing carburators

Originally posted by chrysler_joe:<br /> If you are talking about a Force 9.9 1987-1989 then all you need do is install a larger jet and increase the reed valve opening.If your interested e-mail me and I will try to find the book with the spec. ffjoe@rogers.com

 

[cenzo]

Re: 9.9hp to 15hp just by changing carburators

Unfortunatly I have a 1985 Force 9.9, is there anything to be done there?

 

[cenzo]

Re: 9.9hp to 15hp just by changing carburators

Unfortunatly, I have a 1985 Force 9.9

 

[chrysler_joe]

Re: 9.9hp to 15hp just by changing carburators

If your motor is 13c.i. nothing can be done but if it is 15c.i. then you can change it <br />I'll check my book and let you know

 

[cenzo]

Re: 9.9hp to 15hp just by changing carburators

As a matter of fact is is a 15ci. (15.41 to be exact)