Riva throttle body spacer.

[swatski]

Unless I have this all wrong, and PLEASE let me know if i do, and Im basing this on Williansone46 pics, the ribbons are made into or attached to the throttle body insert? (item 17 on the exploded view). If you can just take out the ribbon, youre golden and know it for a fact. If you have to remove the insert itself to get the ribbons out (they are attached in a way that you cant remove them without removing the entire insert) you have to put something in that void so your airflow laminar matches the throttle body, otherwise the lip the insert is riding on will ruin anything you gained by removing the insert.

And Im not endorsing Riva. (BUT when i raced jetskis they are damn good!) I even state that if you have to remove the insert, here is how to make one ;D

Also, when air/liquid flow are talked about, often what the pencil says you see in the real world. Not trying to argue you, but honestly, you do have it backwards. What you DO often see is the misapplication or not taking the system as a whole into account so the science gets discredited when in actuality what you changed (streamlined) did work but the bottle neck was elsewhere.

Let me give you an example. Exhaust. The exhaust on our boats, or any mass manufactured engine, is so restrictive, optimizing it can give you HUGE benefits to both power and fuel consumption. But federal regs, based on cars, say that certain things have to happen in exhaust systems for a clean burn.

Okay, just quickly, the ribbon is fitted inside the throttle body/intake manifold with a rubber ring/seal. (BTW - that thing (the rubber seal) should not be left behind - if it gets sucked inside the engine - causes a lot of damage - someone posted on that here or the other site with pictures, don't remember now). Plenty of pictures of ribbon delete. I do not know of anyone reporting performance benefits of replacing that rubber seal with the riva ring. I understand the theory.

Basically, the air flow appears to be limited by the ribbon, but does not seem to be further limited by the turbulence resulting form the absence of a ring or a seal (which would serve to smooth out the air passage) - it just does not seem to matter if you have the ring in there or not.

I believe that your statements about the potential benefits of opening up the exhaust are not well founded. Strait through exhaust systems have been tried in jet skis and boats and generally discounted for having small effect on performance/power increase and large effect on increasing the noise. If I remember correctly @Speedling has experimented with that, maybe he can chime in.

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[Ronnie]

The engineering aspects of this are all over my head but I removed the ribbons from my 242 ls and did a similar mod on the 230 SX I used to have (there the ribbons and mounts were replaced by "velocity stacks" that had to be installed under after market air filters and there were four stacks per engine). The results for me were the same on both instances, that is no gain in RPM whatsoever (I.e., these are snake oil). My theory is that since I boat at sea level my engines are already running at the maximum rpm allowed by the governor/Ecu. Whatever the cause, I gained nothing and lost or spent about $100 per boat plus an hour of so of time wrenching, not worth it in my humble opinion at all.

For the potential gain I don't think that machining my own better part would be worth the effort. Having no experience with a CNC or similar machine I'd likely need to make several attempts to get it right by that time it would be cheaper to buy something off the shelf. The Rivas are not a drop in alone replacement, you have to remove the ribbon from the rubber liner and reuse the liner with the riva part.

 

[Greg M]

Okay, just quickly, the ribbon is fitted inside the throttle body/intake manifold with a rubber ring/seal. (BTW - that thing (the rubber seal) should not be left behind - if it gets sucked inside the engine - causes a lot of damage - someone posted on that here or the other site with pictures, don't remember now). Plenty of pictures of ribbon delete. I do not know of anyone reporting performance benefits of replacing that rubber seal with the riva ring. I understand the theory.

Basically, the air flow appears to be limited by the ribbon, but does not seem to be further limited by the turbulence resulting form the absence of a ring or a seal (which would serve to smooth out the air passage) - it just does not seem to matter if you have the ring in there or not.

I believe that your statements about the potential benefits of opening up the exhaust are not well founded. Strait through exhaust systems have been tried in jet skis and boats and generally discounted for having small effect on performance/power increase and large effect on increasing the noise. If I remember correctly @Speedling has experimented with that, maybe he can chime in.

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Removing the ribbon absolutely will make a benefit. Hand down. You might not see it or "feel it". The op was at high altitude. His experience is going to be different than someone at sea level.

Revs are revs. This is limited by the ignition. If you were at max, and removed the ribbons, you wont see more rpm. But if you are at altitude... and werent at max... yeah, you will an rpm increase. You would need to have a dyno hooked up at sea level to see the increase in power, more likely you will experience it thru the rpm climb.

Straight thru exhaust, not a fan and agree. There is more at play with exhaust than just airflow as an absolute. Sound harmonics come into play as well as thermal issues. But to have that discussion, its going to get technical

 

[Speedling]

Okay, just quickly, the ribbon is fitted inside the throttle body/intake manifold with a rubber ring/seal. (BTW - that thing (the rubber seal) should not be left behind - if it gets sucked inside the engine - causes a lot of damage - someone posted on that here or the other site with pictures, don't remember now). Plenty of pictures of ribbon delete. I do not know of anyone reporting performance benefits of replacing that rubber seal with the riva ring. I understand the theory.

Basically, the air flow appears to be limited by the ribbon, but does not seem to be further limited by the turbulence resulting form the absence of a ring or a seal (which would serve to smooth out the air passage) - it just does not seem to matter if you have the ring in there or not.

I believe that your statements about the potential benefits of opening up the exhaust are not well founded. Strait through exhaust systems have been tried in jet skis and boats and generally discounted for having small effect on performance/power increase and large effect on increasing the noise. If I remember correctly @Speedling has experimented with that, maybe he can chime in.

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Only on the mr-1 have i tried the full open exhaust. If you think your boat is loud now...
On the mr-1 the throttle bodies and intake are huge for the displacement and rpm. The exhaust even more so. Opening up either won't do any good. With straight through exhaust i had a slight decrease in top speed but it was like 1/2 a mph. The get up and go factor was worse though.
I am assuming the 1.8 is a better design but the exhaust os probably not a limiting factor unless you have the california version.

On the mr-1 we need a ram air intake of some sort and an o2 sensor to dial in the fuel.

 

[Greg M]

Thats why i said exhaust efficiency Speedling. A straight thru exhaust rare does anything but make noise.

omg, what did it sound like? All i can picture in my head are corollas with huge wings!!!!! lol

Speeding? mr-1 open loop?

 

[swatski]

The engineering aspects of this are all over my head but I removed the ribbons from my 242 ls and did a similar mod on the 230 SX I used to have (there the ribbons and mounts were replaced by "velocity stacks" that had to be installed under after market air filters and there were four stacks per engine). The results for me were the same on both instances, that is no gain in RPM whatsoever (I.e., these are snake oil). My theory is that since I boat at sea level my engines are already running at the maximum rpm allowed by the governor/Ecu. Whatever the cause, I gained nothing and lost or spent about $100 per boat plus an hour of so of time wrenching, not worth it in my humble opinion at all.

For the potential gain I don't think that machining my own better part would be worth the effort. Having no experience with a CNC or similar machine I'd likely need to make several attempts to get it right by that time it would be cheaper to buy something off the shelf. The Rivas are not a drop in alone replacement, you have to remove the ribbon from the rubber liner and reuse the liner with the riva part.

I thought we put that issue to rest in the past...

Yes, if you are on the rev limiter with the ribbons in, you will not gain RPM with the ribbons out. Most of the 1.8l boats are not hitting the rev limiter stock and will benefit from ribbon delete. In this context, calling that mod snake oil is nonsensical.
On the other hand, the MR1 HOs are so well vented stock, they do not benefit from intake manifold upgrades (aka velocity stacks). Riva kits for that matter seem like snake oil.

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[Speedling]

Thats why i said exhaust efficiency Speedling. A straight thru exhaust rare does anything but make noise.

omg, what did it sound like? All i can picture in my head are corollas with huge wings!!!!! lol

Speeding? mr-1 open loop?

Ummm less carolla and more dirtbike wound up ready to explode.
Eliminated the waterbox with a straight through pipe. 3" i believe it was. This is something you don't need to try guys...

 

[Ronnie]

@swatski , what I stated makes perfect sense too me. I purchased and installed these mods expecting a performance gain, I got no such performance gain. I would have been better off leaving the stock ribbons in because the mods were essentially useless. That is no pros, just cons by way of cost and time. Snake oil.

Some people swear by them and have gotten a few hundred extra rpm out of them but based on my experience if you are boating at sea level, pass and save your time as well as money.

 

[swatski]

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[blacksapphirez]

don't pay for the insert...just remove and have a nice day

 

[Kevin Sargent]

Actually, you can just remove the spark resistor and not replace it with the spacer. Saves you 80 buck, you will see the same RPM increase.

Also, you can remove the entire air system, go to the K&N website, measure the diameter of the flange, and buy a clamp on K&N Flame arrestor filter. You will definitely have more air flow.

I did this on my 2011 HO SX240. Then I bought a simple 4" L bracket with two holes on each side, attached it to the back wall where the airbox was mounted, cut an outdoor french drain 6" long, and in half. I screwed the drain piece to the L bracket. The K&N cone filter laid right into place. With the spark resistor removed and the entire air box removed, I was spinning 7800 rpm. I never could measure my fuel efficiency, but assume it was better, at lower speeds. Wide open was probably the same or worse.

Food for thought:
Play with your spark plug gap. Especially if you increase the air into your intake. For anyone wanting to understand why the gap is important. I will summarize, and keep it simple.

First - the spark is measured in milliJoules mJ (energy stored characteristics are determined by time, current and voltage. With this being said, the goal is to achieve optimal ignition spark, based on the power of your ignition system.
- the goal is to achieve the highest temperature of burn, across the longest distance possible. [Fuel, Oxygen, heat] = fire = Horsepower - effectively burn all of your fuel in each cylinder, as fast as possible
- FYI Yamaha boats are pretty intelligent, when you increase the Airflow, the computer automagically increases fuel to match the air ratio determined by the engineers.
- The highest temperature, longest burn, can different from boat to boat, and age/quality of the ignition system.
- one ignition system may burn = x (Gap .033 - .040), then at .041 (value x decreases by value y, per .001) So beyond .040 you reduce heat, below .040, you are reducing distance/time.
- another may burn = x (Gap 031 -.035)
* you never want to over Gap, and if you do, your idling RPMs will decrease or bounce around a bit.


All this to share one thing; If you delete your air box like I explained above, maximize your Gap to account for the additional fuel/air. The Gap on my SX240 was set at .040, not the recommended .031 -.035. She ran perfectly. As a matter of fact, with a few other minor things I did to the boat, I could run 55 - 56 mph in perfect conditions.

Ha while I am sharing, a trick for the cooler under the seat. I was sick and tired of lifting it out all the freaking time to dump water ice. I engineered a fitting on the cooler(Home Depot plumbing supplies), attached a clear 5/8 hose from Auto Zone, installed a valve, then ran the hose into my bilge. No more lifting the cooler in and out for me.

I now have 2015 under warranty, with the exception of the cooler, not sure if I can get away with any mods yet. Anyone have the answer to the question?


Cheers

Oh, I forgot to mention why I did the air filter delete. I needed to change my air filters and the dealer told the cost was 160.00 each..... Ha! No thank you, sir! I will stick my finger in my own ass.

 

[swatski]

Actually, you can just remove the spark resistor and not replace it with the spacer. Saves you 80 buck, you will see the same RPM increase.

Also, you can remove the entire air system, go to the K&N website, measure the diameter of the flange, and buy a clamp on K&N Flame arrestor filter. You will definitely have more air flow.

I did this on my 2011 HO SX240. Then I bought a simple 4" L bracket with two holes on each side, attached it to the back wall where the airbox was mounted, cut an outdoor french drain 6" long, and in half. I screwed the drain piece to the L bracket. The K&N cone filter laid right into place. With the spark resistor removed and the entire air box removed, I was spinning 7800 rpm. I never could measure my fuel efficiency, but assume it was better, at lower speeds. Wide open was probably the same or worse.

Food for thought:
Play with your spark plug gap. Especially if you increase the air into your intake. For anyone wanting to understand why the gap is important. I will summarize, and keep it simple.

First - the spark is measured in milliJoules mJ (energy stored characteristics are determined by time, current and voltage. With this being said, the goal is to achieve optimal ignition spark, based on the power of your ignition system.
- the goal is to achieve the highest temperature of burn, across the longest distance possible. [Fuel, Oxygen, heat] = fire = Horsepower - effectively burn all of your fuel in each cylinder, as fast as possible
- FYI Yamaha boats are pretty intelligent, when you increase the Airflow, the computer automagically increases fuel to match the air ratio determined by the engineers.
- The highest temperature, longest burn, can different from boat to boat, and age/quality of the ignition system.
- one ignition system may burn = x (Gap .033 - .040), then at .041 (value x decreases by value y, per .001) So beyond .040 you reduce heat, below .040, you are reducing distance/time.
- another may burn = x (Gap 031 -.035)
* you never want to over Gap, and if you do, your idling RPMs will decrease or bounce around a bit.


All this to share one thing; If you delete your air box like I explained above, maximize your Gap to account for the additional fuel/air. The Gap on my SX240 was set at .040, not the recommended .031 -.035. She ran perfectly. As a matter of fact, with a few other minor things I did to the boat, I could run 55 - 56 mph in perfect conditions.

Ha while I am sharing, a trick for the cooler under the seat. I was sick and tired of lifting it out all the freaking time to dump water ice. I engineered a fitting on the cooler(Home Depot plumbing supplies), attached a clear 5/8 hose from Auto Zone, installed a valve, then ran the hose into my bilge. No more lifting the cooler in and out for me.

I now have 2015 under warranty, with the exception of the cooler, not sure if I can get away with any mods yet. Anyone have the answer to the question?


Cheers

Oh, I forgot to mention why I did the air filter delete. I needed to change my air filters and the dealer told the cost was 160.00 each..... Ha! No thank you, sir! I will stick my finger in my own ass.

Ha! Always learning here. I was not aware of the benefits of adjusting the gap after ribbon delete. Never heard of jet ski guys on greenhulk do that, need to look into it, I am definitely intrigued!
The filter is a good idea, had it moded like that in my 190:


However, after ribbon delete it was a very small gain if any, maybe 50RPM.

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[Kevin Sargent]

You don't have to adjust the Gap. It was more for about over gaping and losing heat, then adding more air and fuel would cause worse performance. Increasing the gap only works if you ignition system is strong enough to spark across the increase distance while maintaining the same temp. Every system will be different. Play with it

 

[swatski]

You don't have to adjust the Gap. It was more for about over gaping and losing heat, then adding more air and fuel would cause worse performance. Increasing the gap only works if you ignition system is strong enough to spark across the increase distance while maintaining the same temp. Every system will be different. Play with it

@Kevin Sargent So, some indeed play with the gap. From what I can find they close it up though - LFR6As have a gap of 0.035", they would adjust it to 0.028" - presumably to advance timing a tiny bit?

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[Jgorm]

This thread is full of misinformation. Tb spacers on port injection efi are 100% waste of money. 100% of the minimal gains are from removing the spark arrester. Gapping spark plugs will be worth 0hp unless you are missing from blow out at high rpms. Turbulence is good when close to the heads. That's why there are swirl dams on many heads. I'm far from an mr1 expert, but I've been efi tuning cars since 05.

 

[swatski]

This thread is full of misinformation. Tb spacers on port injection efi are 100% waste of money. 100% of the minimal gains are from removing the spark arrester. Gapping spark plugs will be worth 0hp unless you are missing from blow out at high rpms. Turbulence is good when close to the heads. That's why there are swirl dams on many heads. I'm far from an mr1 expert, but I've been efi tuning cars since 05.

We are talking about 1.8l engines. Indeed, the effectiveness of those RIVA rings has never been shown in any side-by-side testing (TTBOMK). Still, I would stick those in, it can not hurt to smooth out the intakes' internal profiles and the ribbons are located in front of the throttle bodies, far away from the heads.

The MR-1s are very different and appear to be extremely well vented from factory, my understanding is the "velocity stacks" are really not doing anything there.

What does "missing from blow out at high rpms" mean?

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[veedubtek]

Too lazy/don't have time to read the whole thread to see what we're talking about at the moment.

But, I'd guess he was referencing more a problem turbo cars can experience with blowing out spark @swatski . When upgrading turbos, or cranking everything you can out of them, you'll typically change heat ranges and close the gap a bit as you can "blow" out the spark.

I don't understand how this applies in the current topic, but I'll try to come back and read through it later.