sleeper_dave

You keep this at the DYC?

I think I saw it in the well a couple years ago when we went down to the DYC for the frostbite cruise. I ogled it for a few minutes. If I had the money, I'd be seriously looking at it.

tommymonza

Speed channel had a very interesting story with Gale Banks on it explaining the gains and consquences of boost either supercharged or turbocharged.
Any ways they wrapped up the show with Gale saying the future of engines is twin turbo Diesels.He explained that the limit to boost is the quality of fuel that leads to detonation.Since a diesel runs on detonation there is no limit to boost if you can hold the lowerend together.

He is working on a twin turbo Duramax that puts out 700hp.He is currently racing a truck with the enghine dialed down to 500hp and even though it is heavier than the competetion it is still placing very well.
He said the secret is to get the weight out now.

airship

That the one. I plan to start taking digital pics this summer for the listing. If you remember the tugboat next to it, that is mine as well. Feel free to stop by next time. Always happy to give a tour.

jtmiller02

I don't think that setup would hold together very long at those power levels. There is a reason why all the current production marine diesels are bigger heavier inline 6 blocks. If you could reliably get that much power out of that size package yanmar, cat, cummins and volvo would already be doing it.

If you want 500hp you are looking at around 1800lbs and 7.5 liters of displacement from a production motor. The duramax setup might work and I'm sure its a better setup than the 2 valve from the standpoint of efficiency and power to weight but the only real benefit to longevity is that a lot of older motors tend to dump lots of fuel at idle which can increase engine wear. The newer engines do a much better job of avoiding this. I'd let someone else abuse a few of those before I'd throw my money at it.

Michael1

You could say the same about a gasoline engine, except instead of boost, there's no limit except the RPM at which the bottom end will hold together. Formula 1 engines are running 19,000 rpm. Try that with a diesel. The Audi R10 V12 race diesel runs 5000 rpm. Diesels are RPM limited by two things: 1) the speed air can mix with the injected fuel, 2) the heavy bottom end rotating and reciprocating components needed to support the high compression and combustion pressures.

Michael

tommymonza

I had a 315 hp Yanmar that was only 4 liters and weighed 850lbs and it lasted 4500hours before i repowerd because it was getting old not because it was wore out or broken.The 315 Yanmar is a marinized version of a Toyota.Great little engine.If 4 liters made 315 why couldn.t 6.5 liters easly make 500hp?

TopSpin80

when I put the cummins in my boat ( don't have either yet) I'm gonna name it "CUMMIN HARD" and do some ghosted paint like golddigger in the background "I'd rather be cummin than strokin"

EastGateCustoms

I am thinking of the Cummins route also in a 30 Scarab II I found and hope to get. I bought an 89 and 90 dodge pickup and will marinize the 6bt's wether I get the boat or not.
I was told by a farmer whom did the marinizing for a lobster boat that ..."if you find a 200,000 mile diesel.. it will be broken in well enough...
( I believe he meant that he had heard from someone that if you have a Cummins from Mercruiser that it had a tendancy to wear the cylinders unevenly from the uneven cold spots in the cooling system... I remember him stating something but cannot remember why)
... to marinize and last another 5000 hours + in a marine application. Some tweaking can get an honest 500 horse and 700 lbs of torque in a peak range around 4000 rpm... Thats if you are looking to boogy, and last alot longer than a 525 before needing a rebuild."
I would probably guess that is true.
Like I said... it was his comments... I am still researching tidbits here and there.

Haven't seen/heard of any 525's last 1000 hours yet.
Anyone agree/disagree?

jtmiller02

I run the Yanmar 315 in my boat and my company has 3 identical boats with them. There are quite a few others around here as well with the same setup. The engine is based off a toyota block but has very little in common with the toyota other than the original casting.

The 315 weighs about 950lbs and thats a pretty conservative measurement and does not include the drive either. The engine displaces just under 4.2 liters and does not make a true 315hp. That figure is based on a fuel temp. which is well below what you will experience in the real world. I would say its more around 300 at most in real world use.

You want to get about 65% more power out of an engine with about 50% more displacement, which on the surface sounds reasonable. Dig a little deeper you will find several problems. The 315 yanmar doesn't have a great low end and really hits its sweet spot about 2400rpm up. On my boat it cruises best just a few 100 rpm short of the 3800rpm top end. This is mainly due to the fact that any more prop would kill the hole shot waiting for the turbo to spool. The yanmar 315 has about 550lb of torque. You will not be able to create a reliable diesel with 65% more power that will hold together at those engine speeds.

Step up to the 500hp yanmar and you are now creating a whopping 1100 lbs of torque requiring a huge increase in rotating mass and mass of the engine block itself. The displacement increases to 7.4 liters and your max RPM drops to 2900. You now have over 800lbs of torque just off idle. Compensating for the increased mass to deal with the load of 1100lbs of torque means an increase in displacement.

Increasing the engine size only in proportion to your desired power increase and not accounting for lower max RPM would give you an engine with about 6.7 liters. This being proportional to the displacement and output of the 315.

I think its pretty reasonable to consider that doubling the amount of power the engine must withstand increases the engines mass by about 90%. This increase also means an increase in rotating mass and hence the lower max RPM. Proportionally to the 315 this loss in RPM is offset by an additional .7 liters of displacement...not a bad tradeoff.

I think the real question is how strong and how light can you make internals to cope with the high compression and high torque while still being reliable. If you could make a reliable 500hp diesel that could turn 3600rpm for hours at a time like the 315 will then you might be able to get that much power from the smaller package.

I simply don't see it being such an easy task otherwise the big boys with the R&D budget wouldn't be wasting so much iron on these 1800 beasts.

jtmiller02

I haven't either, but I have run a 496 with 3200 hours on it, last I heard she was still going strong with several hundred more.