Have done a dyno test on a BPS 5500 engine now.

A base 45 Mag Engine give about 45 hp so the Iron Mountain Heads give about 8-9 hp more in our test.

The 5500 engine have:
- Iron Mountain Heads
- BPS Oversize Stainless Valves
- Mikuni 42mm Carb
- BPS Black Death Intake
- K&N air cleaner
- BPS Cam
- BPS Stroker Rod & Pistons
- Roller Rockers

We have tested with exhaust system:
- BPS "Q" Stainless Muffler
- Straight flow
- Special catalytic exhaust system for low emissions called Preburn Catalytic System, a pend prototype from Sweden.
Not much difference between the system, about 1 hp.

On the first test we have messure 53-54Hp at 4800-5200Rpm and torque on 95Nm at 3000-3500Rpm.
We will have a complete report next week from a longer test.
We do not use any RMP limit in the test bench so 5200 is maybe little high to run the engine on in long term.
But as you can see the best torque is at 3000-3500Rpm.

But do not run this engine without a rev limiter in real life!
In this test we can control the engine good and know the risk.
But it revs much more than 5200 rpm and this can damage the engine, or lets say its damage the engine!

The engine have a very fast response and goes very nice!

Have tested allot of parts from other manufacture to but so far BPS have the best performance parts I have found together with good support.

Nice , so you say the bps Q flows pretty good? I've heard mixed reviews on them not flowing as good as some of the others. Im looking to quiet my rig down and thought that would be the ticket. Your thoughts?

I am no motor expert...

What sort of HP/ Torque loss comes in when you add the belt, lower unit, prop & water you're riding in into the equation? I know this is a tough question to gauge, perhaps a percentage would be an appropriate answer?

I noticed the test was off the motors output shaft.

you may take this with a grain of salt, But in automotive applications you usually lose between 10-15% through the drivetrain. i would think it would similar to these motors due to fact that you have the drag on the boat from the water, prop slip, etc......

I would guess it could lose about 20 percent. Like an engine does in a car when you add a tranny and rear differential.


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I am here: http://tapatalk.com/map.php?b5bnng

He's out of Sweden and using the motor for a hovercraft application, interesting.

good info man keep posting

I just googled that dyno and that thing is $5k for the basic one!!

Awesome first post!

I thought we had another DDM on our hands after that choppy English

Thanks for the report Kemis. It is good to see other (independant) testers check to verify what the factory has done too.

Only piece of advice that I have is to get rid of that K&N air filter. We found that they were too restrictive for the 5500 motor. The new one that they use is made by Tau Ceti, and it is just a flame arrestor (just a metal screen, no filter paper at all) with the pre filter outer ware to keep moisture out.

10-4, that makes since. Good clarification.

Here ya go Will, you should appreciate this one.

This came off of someones boat that insisted on using a K&N, and found one for a 350 chevy that happened to fit on the velocity stack. If you have a 42mm Mikuni you'll understand how big this acutally is, but if not take a look at the second pic for a comparison to a 2 liter bottle.









IMG_4030.JPG




IMG_4028.JPG

I understand what you are saying and I have had motorcycles with smaller breathers producing more horse power, just curious why these need so much air. Less than 1000 cc's, how much is a chevy 350? 5,500 cc's I think...

Much talking about the K&N filter.
Was on the picture but on this picture below we use something else and this do not restrict the air flow much and give little numbers to! Coming back with this as soon I have little time over and get them.

But I should see if we can do a test to se how much this K&N filer really restrict the engine. In our application we do not use this K&N filter. We have a much larger filter on the side. There is no space for a larger filter on the carburetor as someone explain a real filter is big!
If you use a larger K&N filter the exhaust is in the way or it get to o hot.
We use a silicone and aluminum tube to the larger air filter.

The interesting hp for me is on the outgoing shaft. How much hp you get in the end of an application is not interesting because the application is different. When you buy a new B&S you have a number on hp and this number is from the shaft. You need a number so you can compare the engines. So measure on the last end is not interesting in this case because you cannot compare the engines then.

But I agree that you have a loss on 5-20% in the transmission.

And sorry for my "choppy English" but my Swedish is bad too so my English is not better.

50hptiller, i am curious about that too. I want to try the bps q but heard it doesn't flow well. After reading this, im wondering how much it matters. Im only stage 1so maybe it'll be ok for me. Not sure.

Welcome to the forum!

Hope you stay around!

Welcome to the forum Kemis, I have a really great friend from Sweden, I hope you stick around!

^^ agreed! Great first and second posts, thank you!

50hptiller explain the exhaust system very good in his post and much more!
The word I chose "Straight flow" may not be the best one.

What we do is testing for a new catalytic exhaust.
So the 3 different exhaust system we tested are:
- BPS "Q" Stainless Muffler
- Straight flow and in the end we have a muffler but no catalytic.
- Special catalytic exhaust system for low emissions called Preburn Catalytic System, a pend prototype from Sweden.

The catalytic system we use need the pulses to preburn the emissions. No more white smoke and a wife that complain that you smell like shit!

The difference in hp between this 3 system seems to be small.

But the system we test you can compare with a system with the "Q" muffler in performance.

But for you mudpeople the "Q" Stainless Muffler, Twin Stainless Muffler or Single Crossover Stainless Muffler or something similar should be the choice.
If you want lower sound the "Q" is probably the best choice and if performance is nr 1 the Crossover and Twin Stainless Muffler may be another one.

Maybe 50hptiller have the answer on this or someone else that have test all 3 on the same engine can explain the difference in performance, sound aso.

I only want to give a indication on how much you can expect from a 5500 engine.

Yes I use 1,5" to 2" and a 15 degrees merge coll on all new exhaust I have done. This should give little better performance they told me. But have 1,5 and 2" on the test exhaust to but a higher angel and not a real merge coll.

But you talking about a 42" long pipe.
Is this after the merge to 2" pipe?

We have about 42" pipe after the catalytic today.
And about 20" befor. Need a absorber before the cataltic for the vibrations.

Kemis: You might be familiar with SKanska, one of the top 5 construction companies in the world organized and headquartered in Sweden. My daughter works as a civil engineer for them in New York. These are some of her projects:

Major projects

Major projects in the United States include the New Meadowlands Stadium (MetLife Stadium, home to the Giants and the Jets NFL franchises), completed in 2010.[13] Skanska is also the construction manager for Madison Square Garden's renovation project, due to be completed in 2012.[14] Skanska has also won the Alaskan Way Viaduct project in Washington: the project worth SEK840 million ($115 million) involves the construction of a new 1.3 kilometer viaduct on the southern section of the Alaskan Way on the State Route 99 bypass in downtown Seattle and will be completed in 2013. [15]

Another continuing major project is the renovation and addition to the United Nations building, due to be completed in 2014.[16]

Other continuing major projects include the restoration of the World Trade Center ground zero site including the removal of debris, the reconstruction of the PATH and New York City Subway and the creation of a World Trade Center Transportation Hub, due to be completed in 2014.[17] Skanska is also a member of consortium responsible for the Second Avenue Subway tunneling project, due to be completed in 2016.[18]

Sorry, I was only trying to make him feel welcomed. Carry on.

The talk about the K&N filter that we use not have enough air flow to support the air to the engine is "almost" wrong. We have now measure up the difference between a K&N filter and a free flow with an Air Flow Meter and the difference is only a few %. That is not bad for a air filter that always have a small resistance.
So the rumor that the filter do not give enough air is wrong.

But this is with a new filter!

The conditions can fast changes if the filter starting to get dirty. The marginal may be much smaller on this filter than others like a Tau Ceti air filter or larger filter.

But in the dyno test the K&N filter make no big difference.

But always use a clean filter and an extra micro cover prefilter for easy cleaning and protection. In our case we have water and snow that this micro cover prefilter stop coming in to the air filter and it is allot of snow and water we talking about! See picture of powder snow driving below. This snow cause no problem for the engine when use a extra micro cover prefilter.

Good info kemis ...kool pic too

Welcome!! And thank you for some very interesting info!!!

No I only using 1 micro pre-filters.
Same filter we use as you have for mudboats.
The conditions are very similar as you have.
The picture show drive in snow, but you can also drive on water, land and mud to.
That's why this forum and this kind of product is so interesting for me.
Have follow this forum for some times but it is first now I feel that I have something to chare.

pretty cool information man. thanks!