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GP1800?

gmtech16450yz

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Ok I have more good info for you guys that are seriously interested in knowing more about tuning and these SVHO engines in particular... (BTW, my "Like" rating to post count is one of the highest on this site. Thanks for the "Dislikes" you guys just gave me, it will help balance things out a little better. lol.)

I ran the GP yesterday after doing 3 more "mods". HUGE increase in low end and midrange pull and a solid 81 mph on the stock prop still!!! The limiting factor on top speed now is obviously the prop, I was slamming into the rev limit I set at 8500 on initial take off and on the top end. Raising the limiter would have easily gained more speed, I just didn't feel like it was necessary though, 8500 is as high as I want to run this stock engine. It definitely had the power to pull easily up to probably 9k, which would have been closer to 85 mph, but why?

So the latest mods were pump porting and sealing, a minor air filter change and more tuning work. On the pump, I did the usual tunnel clean up and sealing, but also opened up the 150mm section all the way up to the rest of the 160mm portions and removed about a pound of aluminum from the vane parts of the pump.

On the air filter, I had bought a Riva power filter in the first round of mods. I liked the filter and the flanges they use on the blower, but I didn't like the tubing. There's a really sharp bend right in front of the blower inlet which is never a good idea. So I ditched the entire tube and put the filter right on the blower inlet. I have absolutely no doubt it flows better since on intake tubing, less or none is always better than more.

The other part I worked on was I did more on the tune. At this point, I'm WAAAAYYYYY far away from stock and the "canned" tunes. There are points in the ignition timing table where I'm literally double what they did in the aftermarket tune. And big differences in fueling too. Like I've tried to say, these aftermarket tuners don't seem to understand anything but the WOT areas of tuning. There's huge portions of tables that are untouched from stock in their tunes, and it makes big differences in the way the engine performs in all the rest of the rpm and throttle ranges. There's more to engine management than WOT from 5k to redline, which is what anyone with a laptop can figure out in a couple minutes.

One of the side effects of proper engine tuning? Exhaust sound. When I first started riding this GP, I noticed it had a ton of resonance (most people mistakenly call it "drone") right around 4k rpm. When I put on the through-hull exhaust, it made it even worse. It was almost unbearable to run at that rpm, which happened to be right around where you'd cruise between no wake mode and up on plane. The exhaust noise was literally one of the biggest reasons I decided to tune this GP. Just as I thought, it was the tuning that was responsible for 50% of the exhaust resonance. Even with the through-hull exhaust, the resonance around 4k rpm is far less than it was with the bone stock exhaust and tune.

Long story short, (haha) there is a TON of potential in the SVHO engines. Just in tuning, far better power and response from IDLE to redline and ALL throttle openings is easily gained. There are also significant gains to be made over both the stock tune and the aftermarket tunes as far as fuel mileage goes too. There are parts of both the stock and aftermarket tunes where you might as well be pouring gas directly into the water. lol. I know some of you guys read some of what I say and think I'm nuts, but if you could see how different proper tuning looks like compared to an aftermarket canned tune, you'd be shocked.

Hopefully you guys with SVHO ski's will benefit from some of this info.
 

Speedling

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gmtech16450yz

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Yikes! That looks scary. lol.

The biggest problem with ANY tuning of ANY engine is (IMHO) it should NEVER be done without logging. (Sorry to yell! That's a powerful sentence though and I wanted to make sure it was heard. haha.) Tuning is often the easy part as far as business and sales goes. Logging and being able to interpret logs is the hard part. You can sell devices like that one all day long. Sell the product and you're done. Getting people to buy and set up logging equipment, log and then getting the logs read is much, much harder and doesn't have a very good profit margin.

Perfect example is in the description for that device. They say the manufacturers run lean AFR's for emission reasons. That's both true and very false. Running proper ignition timing and fueling for max power and efficiency often means a lot of ignition advance and actually lean fuel mixtures. That causes NOx, which is a huge no-no for manufacturers bound by emission laws. Stock tunes are often SUPER rich in certain areas to fight NOx. So to modify the mixtures over the entire range like that device would do, would result in so much over-fueling in certain areas that you'd get enough wall washing to blow an engine. Crazy huh?

Without logging how the engine is actually running, there is really no way to know what it needs. Just because a certain rich or lean value is in the tune doesn't mean that's what the engine is running at.

(I had to yell again, those two sentences are a big deal. lol.) I've tuned a cr@pload of engines. I won't tune an engine that isn't being logged. It's like shooting blindfolded. You might hit the target, but you might not.

As far as the mr1ho engines, I have no idea. I only know what I know. lol. I have almost no experience with this marine stuff, and so far I've only been logging and tuning this SVHO engine. Sorry!
 
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Speedling

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Yikes! That looks scary. lol.

The biggest problem with ANY tuning of ANY engine is (IMHO) it should NEVER be done without logging. (Sorry to yell! That's a powerful sentence though and I wanted to make sure it was heard. haha.) Tuning is often the easy part as far as business and sales goes. Logging and being able to interpret logs is the hard part. You can sell devices like that one all day long. Sell the product and you're done. Getting people to buy and set up logging equipment, log and then getting the logs read is much, much harder and doesn't have a very good profit margin.

Perfect example is in the description for that device. They say the manufacturers run lean AFR's for emission reasons. That's both true and very false. Running proper ignition timing and fueling for max power and efficiency often means a lot of ignition advance and actually lean fuel mixtures. That causes NOx, which is a huge no-no for manufacturers bound by emission laws. Stock tunes are often SUPER rich in certain areas to fight NOx. So to modify the mixtures over the entire range like that device would do, would result in so much over-fueling in certain areas that you'd get enough wall washing to blow an engine. Crazy huh?

Without logging how the engine is actually running, there is really no way to know what it needs. Just because a certain rich or lean value is in the tune doesn't mean that's what the engine is running at.

(I had to yell again, those two sentences are a big deal. lol.) I've tuned a cr@pload of engines. I won't tune an engine that isn't being logged. It's like shooting blindfolded. You might hit the target, but you might not.

As far as the mr1ho engines, I have no idea. I only know what I know. lol. I have almost no experience with this marine stuff, and so far I've only been logging and tuning this SVHO engine. Sorry!
I had heard riva made one turbo kit for the mr1. They were unable at that time to crack the ecu. They used this type of tuner to richen. They also blew it up and soon after came the 1.8
 

gmtech16450yz

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85mph here we come!

haha.

Pulled the pump again and pulled the prop. Repitched the cr@p out of it, polished it and put it back in. Hopefully it will get me off the rev limiter on launches and top end. I don't actually care what the top speed ends up being, I'd just like the max rpm to be a little more reasonable at 8200-8400.

20181023_155101.jpg 20181023_155117.jpg 20181023_155126.jpg 20181023_171937.jpg 20181023_171955.jpg 20181023_172021.jpg 20181023_212732.jpg
 

Speedling

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85mph here we come!

haha.

Pulled the pump again and pulled the prop. Repitched the cr@p out of it, polished it and put it back in. Hopefully it will get me off the rev limiter on launches and top end. I don't actually care what the top speed ends up being, I'd just like the max rpm to be a little more reasonable at 8200-8400.

View attachment 84629 View attachment 84630 View attachment 84631 View attachment 84632 View attachment 84633 View attachment 84634 View attachment 84635
Nice polish job!
 

gmtech16450yz

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Thanks. Yeah it looks pretty but it won't make it work any better! It made me feel better than if I'd just put it back in with the heat and tooling marks I made though. Hopefully it will work as good as it looks. That's the thing that's hard about modding boats and skis, it's not like I can drive it around the block afterwards.

When I had the pump off this time I deleted the suction tube and will put a real bilge pump in it. I also added a fitting on the strainer housing so I can run a dedicated line to the intercooler. Both engine and intercooler temps were higher than I'd like to see when I was looking at the logs. I already added a couple of vents on the hull under the steering and I'm tossing around better blower solutions than the one I put in it already.
 

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Thanks. Yeah it looks pretty but it won't make it work any better! It made me feel better than if I'd just put it back in with the heat and tooling marks I made though. Hopefully it will work as good as it looks. That's the thing that's hard about modding boats and skis, it's not like I can drive it around the block afterwards.

When I had the pump off this time I deleted the suction tube and will put a real bilge pump in it. I also added a fitting on the strainer housing so I can run a dedicated line to the intercooler. Both engine and intercooler temps were higher than I'd like to see when I was looking at the logs. I already added a couple of vents on the hull under the steering and I'm tossing around better blower solutions than the one I put in it already.
I dont know why they didnt put a bilge pump in the gp1800. My FZS (which is its predecessor of sorts) has one factory
 

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Your water box has 2 outlets? I am a little confused on the 2 into 1 exhaust.
And is that your oil breather going into the front of the air filter? You should think of getting or in your case making a catch can. I have read its not good for the intercooler cause it can coat the inside air passages with oil lowering the cooling factor
 

gmtech16450yz

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Your water box has 2 outlets? I am a little confused on the 2 into 1 exhaust.
And is that your oil breather going into the front of the air filter? You should think of getting or in your case making a catch can. I have read its not good for the intercooler cause it can coat the inside air passages with oil lowering the cooling factor
Haha I knew a few of those pictures would get a "WTF" from some of you guys! Good questions btw.

The waterbox is the same as the boats, one in and one out. The black pipe is what you get when you buy the Riva through-hull exhaust. The resonance I mentioned (in another post) at around 4k rpm was pretty bad stock. It was practically unbearable with the Riva exhaust. Riding on the back with somebody else in front and going above no-wake speed literally hurt your ears. What I did was something I've done many times before when building exhaust systems, I put a Hemholtz resonator in it. It's basically a dead-ended pipe that comes off the main pipe. If you pick the right length, you can totally eliminate resonance at a certain frequency/rpm. I built a couple into a Magnaflow exhaust on an LS3 that had huge resonance right at 2k rpm. It took me a couple tries to get the length of the tubes right, but when I did the exhaust literally went quiet at 2k rpm. (pics below)

Good question on the crankcase breather. Yes, common internet knowledge loves catch cans and also says having crankcase oil going through the intercooler is a terrible thing. I've built many catch can systems on many engines, some badly need them, others don't. There are some Direct Injected engines that desperately need them to keep the valves from caking with gobs of oily carbon. But I didn't believe this situation needed one, for several reasons. This being a marine engine, I actually don't have a problem with a little oil going through the engine. And it takes a lot of oil to make a noticeable difference in intercooler efficiency.

There are two other reasons/factors that I feel are more important on crankcase breathing though...and reasons why I really don't like the idea of venting to atmosphere like a lot of guys do. The biggest one in THIS situation is actually safety. Venting the crankcase to atmosphere in a jetski means you're filling the hull with hot oil vapors and some amount of gasoline vapors. I've seen plenty of YouTube videos of watercraft explosions, I don't need to try it out myself! With an F/I engine, you could have a lot of crankcase pressure coming out of that vent. I'd much rather the engine ate it back up than having it fill the hull.

The second reason- I like the idea of having the crankcase vent in a low pressure area. That's why they angle the inlet into the air filter tube, so that there's some vacuum on that inlet the crankcase vent is connected to. Actually, the best thing you can do on a high performance engine is to have the crankcase in vacuum with a pump. Putting the crankcase vent so that the intake air pulls the crankcase air along is a good thing. That's why I put the vent fitting where I did on the filter. It's obviously not in a vacuum, but it is in a low pressure area of the filter airflow in WOT situations. So instead of the huge amount of crankcase pressure at WOT simply dumping into the hull, it's being pulled back into the engine where it can be dealt with safely.

So yeah, those little K&N crankcase breather kits that a lot of aftermarket companies sell are a joke. Not to mention the fact that they're about as non-environmentally friendly as you can get. Catch cans can be a really good thing on some engines, but again, I'd prefer to have them vent back into the engine instead of having the little filter on the top like many do.

20170706_100542.jpg 20170706_100644.jpg 20170706_122616.jpg
 

gmtech16450yz

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Well I took it out with that pretty, polished prop and it didn't work as good as it looked! haha.

A lot of the time I'm modding or tuning things, I tend to go too far simply because the results will be very clear if I'm going the right direction. Many times guys will make changes that are so slight that they get mixed results and it's not clear if they've made an improvement or gone backwards. So on my prop I said "I pitched the cr@p out of it". I went too far. Not horribly far, just farther than I wanted.

On the stock prop I was hitting my 8500 rev limit pretty hard. It was running a solid 80mph and acceleration everywhere was brutal. On my pretty polished prop max rpm was 7700, top speed was 76-77mph. Acceleration was super soft everywhere. It even slipped under hard, slow maneuvers and would over-rev.

So instead of messing with the stock prop again, I ordered a Solas from Impros. David there took a 13-20 and pitched it to 13-19. It should be just right, but I ended up buying a Lucky 13 cone also since they were on sale for $250. If the rpm's are too low with the cone, I'll probably bore out the nozzle to bring them into the range I want. I also ordered the ride plate off a '19 GP1800, it's supposed to be identical to the Riva plate. The stock '19 plate was $87, the Riva plate is $250. lol. The '19 plate is a little bit longer, it should help keep the front end down a little now that I'm at these higher speeds. I'm also going to weld an extension on the RIDE arm for the trim so I can try different leverage points/range of total trim.

So much modding! It's pretty much SOP for me though, I just want it set up the best it can be right off the bat so I can just use it. Just like the boat, I spent a ton of time modding it just right when it was new, now I just use the cr@p out of it and everything just works like I want it to. The GP will get there, just needs a little more time and money thrown at it. haha. The end result will absolutely be worth it though, this thing is a freakin' blast!
 

Nsboost

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Well I took it out with that pretty, polished prop and it didn't work as good as it looked! haha.

A lot of the time I'm modding or tuning things, I tend to go too far simply because the results will be very clear if I'm going the right direction. Many times guys will make changes that are so slight that they get mixed results and it's not clear if they've made an improvement or gone backwards. So on my prop I said "I pitched the cr@p out of it". I went too far. Not horribly far, just farther than I wanted.

On the stock prop I was hitting my 8500 rev limit pretty hard. It was running a solid 80mph and acceleration everywhere was brutal. On my pretty polished prop max rpm was 7700, top speed was 76-77mph. Acceleration was super soft everywhere. It even slipped under hard, slow maneuvers and would over-rev.

So instead of messing with the stock prop again, I ordered a Solas from Impros. David there took a 13-20 and pitched it to 13-19. It should be just right, but I ended up buying a Lucky 13 cone also since they were on sale for $250. If the rpm's are too low with the cone, I'll probably bore out the nozzle to bring them into the range I want. I also ordered the ride plate off a '19 GP1800, it's supposed to be identical to the Riva plate. The stock '19 plate was $87, the Riva plate is $250. lol. The '19 plate is a little bit longer, it should help keep the front end down a little now that I'm at these higher speeds. I'm also going to weld an extension on the RIDE arm for the trim so I can try different leverage points/range of total trim.

So much modding! It's pretty much SOP for me though, I just want it set up the best it can be right off the bat so I can just use it. Just like the boat, I spent a ton of time modding it just right when it was new, now I just use the cr@p out of it and everything just works like I want it to. The GP will get there, just needs a little more time and money thrown at it. haha. The end result will absolutely be worth it though, this thing is a freakin' blast!
Heyman. Big GM hotrodder here. Built and tuned my 1100hp trans am myself. And I fully with your opinion on the canned tunes. I don’t even need a wideband… the plugs and oil tel the story on this Riva tune that’s in my ski. It’s dog ass rich.

So I don’t want another shit tune. I want to tune it right. But the maptuner is so overpriced it’s not even funny. I own efilive. I own hp tuners. I own tuner cats. No ECU software and device should cost as much as the maptuner. It’s highway robbery and it’s laughable the boat guys think it’s ok. Especially considering the half assery you get with canned tunes.
What are you using to change your tune? Did you cave and buy the maptuner and exorbitant edit license? Or did you find a alternative? Please let me know man!
 

mrcleanr6

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Yes the maptuner is expensive and i agree its overpriced. Especially the tuning license. It does have the std tunes it comes with but with an afr gauge on the ski riva will work with you one on one and write a custom tune for you at no additional cost. None of the stock tunes would work for me so they wrote my tune for me. I kept testing and they kept modding the tune until it was right.
 
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