Help with engine options

[Germaine Marine]

The flash in the motor coupled with the some hard part changes makes that motor run pretty good... I really like it against the 2/1 as an alternative to the 575. In any of the 1.5-1 boats I just dont think its worth it.

2/1 460 screams though for sure. Where its tuned coupled with that trans it runs like a bad ***.

[cbath]

I run a 400 in my Z3 at Elevation constantly with added lead and have plenty of power. Top speed isn’t fantastic, but I bought it to surf not cruise. That said, with a slight prop change I can still surf and get 38 mph at Powell...


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[freeheel4life]

One other thing to consider with the SC is that Indmar requires a 15-50 Full Synth(we are running 25-50) but regardless its a good jump up in price compared to the 5-30 that 400 and 440 run. Additionally if you are into doing your own maintenance the impeller is nowhere near as easy to get to on SC vs the 440. Plus up front cost and continued requirement for the high octane. We boat in McCall occasionally(just over 5,000ft) and we have lots of customers up there that are running 400's and 440s just fine, with the right prop for the job.

[007]

If you are running a lot of lake between sets, maybe the bigger motor is better for you. That said, once you get used to a 25 mph cruise and a WOT of 38...the 400 in my '15 Z3 is a great motor. Seriously, I've never had an issue with not enough torque no matter how many people/ballast I have in the boat.

Yes, I've been passed by my buddies running down the lake, but I'm ballasted the minute I can and run much of the time at surf speed. The way I use my boat I'd not opt for the biggest motor.

[Bakes5]

For reference...at 4800 feet, no ballast, 440, 2016 Z3, 1:1.5 trans

2419 speeds
30 mph = 4200

Speeds with OJ 948 (15"x14pitch)
28 mph = 3650
30 mph = 3872
31 mph = 3960
32 mph = 4100
WOT = 39 mph = 5513

Overall the 440 is fine on the Z3. The 14 pitch is the sweet spot for how we use our boat. Im sure the SC would be even better but it sounds a little bit like a pain in the butt.

[Germaine Marine]

Ill play too..

Rzx 3 w/575 and 1.5/1 4000ft.

Acme 16 x 16 (Heavy weighted prop option)

30 Mph = 3510Rpm
35 Mph = 3800Rpm
37 Mph = 3920Rpm
39 Mph = 4200Rpm
41 Mph = 4540Rpm

Wot = 44MPH at 5020Rpm

Loaded
(4760lbs of total ballast)4 people with full fuel
*Taps 3 On

11.0 Mph = 3000Rpm
11.6 Mph = 3150Rpm
11.8 Mph = 3300Rpm
12.0 Mph = 3450Rpm
12.5 Mph = 3550 Rpm

[Bakes5]

Hmmmm.....maybe the 575 is the engine to get It would certainly be friggin awesome on a Z3 that starts off weighing 1000lbs+ less than an RZX. That said, I have never, not once, seen 93 octane gas....anywhere.

Out of curiosity, what is WOT for the 575.....5000 RPM?

[007]

Hmmmm.....maybe the 575 is the engine to get It would certainly be friggin awesome on a Z3 that starts off weighing 1000lbs+ less than an RZX. That said, I have never, not once, seen 93 octane gas....anywhere.

Out of curiosity, what is WOT for the 575.....5000 RPM?

Believe it or not, I can get 93 at one location on the water. However, I can't get 91 anymore. Everything else near me is 89 and the 400 is supposed to run on 91, so she usually gets alternating tanks of each.

[hcooperrn]

For running at altitude, I believe that octane ratings are lower, usually by 2, and provide the same detonation protection, so if 93 is required at sea level, 91 works at altitude, and so on.

[JCP]

That would be correct/safe for a non super charged or turbo charged engine.

[Germaine Marine]

I run mine on 91... no issues, I have some friends that have over 500 hours on the 575 using 89. I know its not recommended. This isnt a heavy built motor... thats running a ton of boost. I think 91 is fine really..

[Germaine Marine]

Hmmmm.....maybe the 575 is the engine to get It would certainly be friggin awesome on a Z3 that starts off weighing 1000lbs+ less than an RZX. That said, I have never, not once, seen 93 octane gas....anywhere.
http://www.tigeowners.com/forum/newr...reply&p=787789
Out of curiosity, what is WOT for the 575.....5000 RPM?

Depending on prop I think its closer to 5200.

The 575 in a z3 would be insane. That hull is so much more steamline through the water then the Rzx. My guess is you would have heavy weighted sub 3k RPM surf boat with a cruise of mid to upper 30s and a WOT speed of around 47-50MPH depending on when it started to bunny hop.

[ski_antique]

Maybe it’s in my mind but my 440 didn’t pull as hard or get as good of mileage with 87 vs 93, so for me there is no change to go to 93 because i’m alreay there(and it’s cheap and available right now). I’ve always been wary of all the gizmos in the supercharged 575, so I’m one of the very few in the 460 camp.

[chpthril]

Indmar states that 89 oct is the recommended fuel for the 440. So, there would not be a benefit to going with 92 or 93. Contrary to the fuel refiner's marketing, octane levels actually work revers of what the marketing leads you to believe.

Performance standards are retained by running the recommended oct, or higher depending on whats available. Engine performance is not improved by running a higher oct, simply maintained. Running a lower then recommended oct can lead to a reduction in performance and possible engine damage.

Also take with a grain of salt when you read that knock sensors detect the fuel octane being used. Knock sensors detect knock, they to not taste fuel. They are typically located in the block, often times into the water cooling jackets, no where near the fuel or combustion system. Knock sensors do not know or report what the cause of knock is, they just report knock.

I would not want to rely on a sensor to detect pre-ignition because I choose to run the incorrect fuel. Wearing a seatbelt does not make speeding safe.

[KoolAid]

Mike is correct. The knock sensor is piezo speaker. It's listening and when it hears a knock, resistance changes and the engine dials back timing until its resistance is within range. SBC's have them in the water jackets near the bottom of the engine, Raptors have them on the heads by the intake manifolds which is a lot more precise. No real advantage to running higher octane unless you have old fuel in the tank and you are added new fuel for the season. At that point I would always go higher octane for the first tank.