Start to Finish: Building Our 50' Skater
01-05-2018, 01:25 PM
#1531
Registered
It Runs. Bet some dude at Nest is going WTF is up with this webcam traffic in Utah... 
01-05-2018, 03:26 PM
#1534
Registered
I broke it.
Platinum Member
01-06-2018, 12:11 PM
#1540
Registered
Testing at Jordanelle reservoir,
We started out logging the data from the computer trying to get on plane and making changes to how the computer controlled what had precedence in the chain of command. Normally the computer would control how much fuel it would let you have according to what the boost, intake temp, rpm, water temp, ect. was to where it would keep the air fuel ratio from letting it smoke, but we needed to be able to control the fuel with the throttle to get it to spool off the line. After we got it to let us control how much fuel it would get it would smoke but allow us to build enough rpm to get on plane. Then we started playing with the tunes on how much power we could make and still have a usable exhaust gas temperatures. The first few passes we had it on the lowest tune which would be around 850 HP at sea level but we were at 6,200 feet of altitude which would drop the HP to around 700 - 720 HP. This was causing some of our problem getting it to make power to spool the turbos. With that tune we could run the boat wide open and not have the exhaust temp go over 1200 degrees and the boat would get up to mid 90's MPH and was porpoising and on this little lake we did not have enough length to get through the porpoise. Then when we turned the tune up we were running too high of an exhaust temp to get on plane. To get the boat on plane the rpm has to be around 4000 and at that high of rpm the turbo cannot let the exhaust out fast enough so it builds up heat. So we ended up putting it on the low tune and got it on plane and then turned it to tune 2. At tune 2 it was fine when we were running 3200 rpm with it wide open accelerating but when the rpm would get closer to 4000 the exhaust temp would start climbing to 1,800' so we would let off. We Decided to go ahead and run the highest tune (5 most fuel) so it would not be running so lean. That did bring the exhaust temp down to a more reasonable temp (1390'). When we were putting the other engine back together we broke the studs loose that were holding the turbo to the manifold, the holes the studs were in were drilled out to big so they had just been welded on the backside where they were flush to the flange which is not enough strength. We broke all of them out and took some studs and ground a taper into them so the weld would not just be across the flat on the back but would be down the sides to give the weld more surface area to hold. We had talked about taking the other turbo out and changing its studs but got in the boat and tightened them and they held so we thought they were ok. When we ran the highest tune it was running along and you could tell it had a lot more power but right after we got up and going the studs broke and let the turbo lift up a little bit so it was dropping boost and making a lot of smoke so we stopped.
In the end having the engine builders in the boat showed them a lot of how engines work in this style of boat because you cannot explain it enough for someone to know how to design the engine and tune it till they see what it does in the boat. After talking about it all night we have decided for it to run right we need more low end to get on plane easier and then need more flow on the top end to run a high enough rpm to go fast. Making an overdrive box would solve some of the top end rpm problem but would make more of a problem coming on plane. Would a two speed transmission help? yes, but I don't have any of mine left and the ones you can buy weigh 800 lbs. It would help it spool off the line but would not solve some of the problem of low speed running dropping off boost.
We are going to pull the engines back out of the boat and take off the exhaust and turbo system and make a new manifold with a compound turbo system. With the compound turbo we can run one that is smaller then what we have that will get us on plane easier and then once the boost comes up it will open a waste gate that will let a lot of the exhaust flow by-pass it and go to the bigger turbo which will be bigger then what we have so it will not be as much of a restriction and let the rpm come up with out gaining exhaust temp. It will also be able to make more boost which will let us have more HP and higher efficiency.
We started out logging the data from the computer trying to get on plane and making changes to how the computer controlled what had precedence in the chain of command. Normally the computer would control how much fuel it would let you have according to what the boost, intake temp, rpm, water temp, ect. was to where it would keep the air fuel ratio from letting it smoke, but we needed to be able to control the fuel with the throttle to get it to spool off the line. After we got it to let us control how much fuel it would get it would smoke but allow us to build enough rpm to get on plane. Then we started playing with the tunes on how much power we could make and still have a usable exhaust gas temperatures. The first few passes we had it on the lowest tune which would be around 850 HP at sea level but we were at 6,200 feet of altitude which would drop the HP to around 700 - 720 HP. This was causing some of our problem getting it to make power to spool the turbos. With that tune we could run the boat wide open and not have the exhaust temp go over 1200 degrees and the boat would get up to mid 90's MPH and was porpoising and on this little lake we did not have enough length to get through the porpoise. Then when we turned the tune up we were running too high of an exhaust temp to get on plane. To get the boat on plane the rpm has to be around 4000 and at that high of rpm the turbo cannot let the exhaust out fast enough so it builds up heat. So we ended up putting it on the low tune and got it on plane and then turned it to tune 2. At tune 2 it was fine when we were running 3200 rpm with it wide open accelerating but when the rpm would get closer to 4000 the exhaust temp would start climbing to 1,800' so we would let off. We Decided to go ahead and run the highest tune (5 most fuel) so it would not be running so lean. That did bring the exhaust temp down to a more reasonable temp (1390'). When we were putting the other engine back together we broke the studs loose that were holding the turbo to the manifold, the holes the studs were in were drilled out to big so they had just been welded on the backside where they were flush to the flange which is not enough strength. We broke all of them out and took some studs and ground a taper into them so the weld would not just be across the flat on the back but would be down the sides to give the weld more surface area to hold. We had talked about taking the other turbo out and changing its studs but got in the boat and tightened them and they held so we thought they were ok. When we ran the highest tune it was running along and you could tell it had a lot more power but right after we got up and going the studs broke and let the turbo lift up a little bit so it was dropping boost and making a lot of smoke so we stopped.
In the end having the engine builders in the boat showed them a lot of how engines work in this style of boat because you cannot explain it enough for someone to know how to design the engine and tune it till they see what it does in the boat. After talking about it all night we have decided for it to run right we need more low end to get on plane easier and then need more flow on the top end to run a high enough rpm to go fast. Making an overdrive box would solve some of the top end rpm problem but would make more of a problem coming on plane. Would a two speed transmission help? yes, but I don't have any of mine left and the ones you can buy weigh 800 lbs. It would help it spool off the line but would not solve some of the problem of low speed running dropping off boost.
We are going to pull the engines back out of the boat and take off the exhaust and turbo system and make a new manifold with a compound turbo system. With the compound turbo we can run one that is smaller then what we have that will get us on plane easier and then once the boost comes up it will open a waste gate that will let a lot of the exhaust flow by-pass it and go to the bigger turbo which will be bigger then what we have so it will not be as much of a restriction and let the rpm come up with out gaining exhaust temp. It will also be able to make more boost which will let us have more HP and higher efficiency.
