Older 2 stroke 130hp & 115hp

[Jason2tpa]

I see a lot of 130s hung on boats, the older 2 stroke like mine. This had me wondering what the major differences of engine specs between the 130 & 115. So I found a 130hp service manual (S130TLRW) for the same year and model as my 115hp, which is '98 S115TLRW, and I compared engine specs. Here's are the key elements I found:

Max Output of 130...95.6hp @ 5,500 rpm
Max Output of 115...84.6hp @ 5,000 rpm

Max Fuel Consumption of 130...56L @ 5,800 rpms
Max Fuel Consumption of 115...49L @ 5,500 rpms

Displacement....same

Bore/Stroke.......same

Compression ration....same

Dry Weight........same


So what gives? With the small differences noted above, how does the 130 engine generate 15hp more than the 115?

[ausnoelm]

You need to compare every part in both parts list, and that isn't 100% positive, but, there can be lots of differences, like the heads, carb size, exhaust, port timing in the cylinder, all sorts of stuff.

[pstephens46]

How does a 115 produce only 85 hp?

Never mind....must be KW...

[dray0151]

Camshaft lift/lobes etc could be a bit difference and as stated above the heads, timing etc.

[ausnoelm]

Not too sure the cam specs are listed on the 2 strokes parts list.

[Jason2tpa]

For those wanting to take the time to compare, the specs for both 130 & 115 engines of the same model are found in the same service manual here (1998):
https://www.vansoutboardparts.com/se...115w-130w/file

[ausnoelm]

We don't want to compare anything, it's your desire to get 130HP out of a 115.

[Jason2tpa]

We don't want to compare anything, it's your desire to get 130HP out of a 115.

Negative. I have no desire, nor did I state so. Take a gander at my initial post to understand what I'm asking.

[99yam40]

to gain HP you have to burn more fuel and mix more air with that extra fuel.

And as stated you listed KW as HP numbers

[DennisG01]

An engine is simply a pump. If you compared all the spec/components and they are the same then, as mentioned, the only other variable is the amount of air and fuel. More air/fuel in at the proper stochiometric (may have spelled that wrong) ratio (since it's a gasser) = more power.

[Jason2tpa]

That makes sense

[boscoe99]

I see a lot of 130s hung on boats, the older 2 stroke like mine. This had me wondering what the major differences of engine specs between the 130 & 115. So I found a 130hp service manual (S130TLRW) for the same year and model as my 115hp, which is '98 S115TLRW, and I compared engine specs. Here's are the key elements I found:

Max Output of 130...95.6hp @ 5,500 rpm
Max Output of 115...84.6hp @ 5,000 rpm

Max Fuel Consumption of 130...56L @ 5,800 rpms
Max Fuel Consumption of 115...49L @ 5,500 rpms

Displacement....same

Bore/Stroke.......same

Compression ration....same

Dry Weight........same

So what gives? With the small differences noted above, how does the 130 engine generate 15hp more than the 115?

As 99yam notes, more air/fuel being allowed into the motor will result in more HP. This appears to be what is being done with the S130 versus the S115. Block is different (could be porting allowing more air in and more exhaust out) and the carburetors are different (jets are larger indicating more fuel flow). Supposition is that the carburetors for the S130 allow more air. The jets are sized to accommodate the additional amount of air.

In the automotive world it is very common to simply install a bigger carburetor to get more HP. Of course changing the cam shaft to go with the larger carburetor will further increase the HP. The cam shaft allows more air into the engine while the carburetor is sized to fit that amount of air. Another common trick in the automotive world is to install headers instead of the cast exhaust manifold. More exhaust out accomodates more air coming in. More air coming in equates to more HP.

[Jason2tpa]

As 99yam notes, more air/fuel being allowed into the motor will result in more HP. This appears to be what is being done with the S130 versus the S115. Block is different (could be porting allowing more air in and more exhaust out) and the carburetors are different (jets are larger indicating more fuel flow). Supposition is that the carburetors for the S130 allow more air. The jets are sized to accommodate the additional amount of air.

In the automotive world it is very common to simply install a bigger carburetor to get more HP. Of course changing the cam shaft to go with the larger carburetor will further increase the HP. The cam shaft allows more air into the engine while the carburetor is sized to fit that amount of air. Another common trick in the automotive world is to install headers instead of the cast exhaust manifold. More exhaust out accomodates more air coming in. More air coming in equates to more HP.

Boscoe never disappoints. Big thanks bud for taking time breaking down the differences.