I recommend a new engine builder, because they are selling you the biggest bunch of cr@p I've ever heard of. If you can't get 1 hp/cu. in. for over two hours on an engine, then throw it away, and get a different engine. Automotive engines achieve that specific output and much more, and they pass 200 to 400 hour WOT durability tests. Even GM's Marine stock engines pass 300 hour WOT tests, and that's with cast parts.

How many hours of durability testing do these marinized Duramax's have? I'm going to guess "none". Almost no one in the aftermarket has the equipment to run long term dynomometer durability tests. They let the customers do their testing.

Michael

gramp we know who you are

That boat went faster than 101. I ran it at 110.

How fast did tommy bahama run ?

I am looking at this strongly for my next application, when ever that may be. The co. in Mich., from what I've been told, (and it's nobody on this thread), are making great strives, and have tested their product thouroughly. I really enjoyed my Yanmar diesel 43 Nortech except the top end number. I even loved those PITA Arnesons...just kidding RIK... I prefer the straight 6's for reliability, but am looking forward to the development of these Duramaxes. Right at this moment it is hard to beat these Merc 700's and #6's that I have. I just dont want to trade for a drop in top speed, or even reliability. Just not certain if like mentioned above does 750hp diesel = a 525 boat in performance...Jeff

call Curtis for more info 626-261-0710

First, I'm not trying to p*ss anyone off I just want to know why & how because I have been out of this for many years and my kids are dragging me back in now(not that it's hard to do!). The world may have passed me by and I didn't even know it!!!


1) If you take a gas engine and build it with an aftermarket block, heads, crank, rods, pistons, valve train assembly, elctronic ignition, etc, etc. and turn it at 5,5000 rpm to make peak HP.

Then you take a Duramax diesel engine with standard block & heads, install an aftermarket crank, rods, pistons, & valve train all most likely from the same people that built the compenents for the gas engine and spin it to over 4,000 revs (the rotating mass has to be lighter than stock to do this) to make peak HP.

Why would the diesel last so much longer than the gas engine and be able to run at WOT so much longer other than it turns slower?

In my mind you have effectivly taken every advantage the diesel had over the gas engine and gotten rid of it (slower rpm + bigger cui + less Hp per cui = longer life)


2) When you talk about running it on the "dyno", we had 3 different ways to gauge or test output on a dyno (I'll list them below). Do you still use the dyno in these ways or have times changed, because each method could produce different number by 20%.

1 - set dyno with a fixed static load and accelerate the engine from idle to full rpm. The time it takes to accelerate that load gives you the Hp output of the engine

2 - adjust load on dyno and accelerate engine until you reach peak Hp, again this is a series of acceleration tests with varing loads, not a steady state for long periods

3 - set engine at desired rpm and adjust load and throttle until the engine starts to drop in rpm, that is peak Hp and then you can back 5% load off of there and run for as long as you want (or things fly around the dyno room)

Thanks, I just want to know am I oboslete in my thinking?

this is what I'm talking about w/750 on a 46 skater 110??? thats sounds pretty fast for 750...I really dont think you can go any faster with gas motors and I.m sure those 750 were realiable....correct me if im wrong...what was the weight and what rpm did you run with what transmisions...........

Rik,then what happen with your theory power to weight ratio that you explained, if 750 diesels(seatek) run 110mph when I doubt a750 gasoline would do that mind 50%less weight then you guys are contradicting yourselves....

They were not set to overdrive like in a race boat.

The boat was HEAVY, like 18-20K lbs heavy. The engines were Seatek 750's which made some 1,300 lbs of torque.

Are they reliable? That is a relative term.

Would a set of big cubic inch gas engines with a blower push the boat to 110. Probably, straining itself. 750 @ 5,000 with a 1.5 gear puts out almost 1200 lbs of torque and then you loose the extra weight. So yea, it'd do it. It too though would be balls out full time to do it.

My point is, there is not magic. Yea there is a lot of smoke and the girls have the mirrors but no magic to power sources.