gas or diesel

[grimreaper]

Hey, here is a question for you guys. Which do you think is better? A twin gas with 180hrs on them, or twin diesels with 550hrs on them. Both are kept in fresh water. I don't know when diesels are considered to be high in hours.<br />Thanks.

 

[JB]

Re: gas or diesel

As a generality, Diesels outlast gas engines about 4 to 1, outweigh them by a lot, outnoise them and get much better fuel mileage.<br /><br />Your question is too open to answer. What does "better" mean? What gas engines? What Diesels? What boats?

 

[grimreaper]

Re: gas or diesel

Sorry, <br />I mean which will need major repair or replacement sooner. which have the least amount of problems if both are cared for properly in general.<br />the boat is a chris craft 38'<br />The gas are Twin Volvo 450's inboard<br />the diesels are twin cummins

 

[voxmorgan]

Re: gas or diesel

My vote is for the diesel due to the size boat. Diesel engines are the true Work Horse of America, but you don’t see them in racecars. If you are looking for longevity then consider the following. Using the ratios JB provided to help you compare the two Gas =1 to Diesel =4, so 1/4 . If you have 180 on the Gas engine and 550 on the Diesel engine you’re at a ratio of roughly 1/3. At this point you still have to put 200 more hours on the Diesel before you reach the ratio ¼ or 180 / 720. If you use the current hours (180/550) and add 200 hours to them you would end up with a ratio of ½ or 380 / 750. At this point in theory you would have to put an additional 770 hours on the Diesel engine before reaching the ¼ ratio. If you want longevity I would go with Diesel all the way.

 

[cmyers_uk]

Re: gas or diesel

Ive always read that your better off with a boat thats been reguarly used and maintained than a boat with low hours. Lack of use is a killer to an engine. One think to look at is cost of servicing , parts etc. Have they both been serviced by main dealer is one in warrenty etc. Proof of winterization. In the UK I would go diesel every time as its 38pre litre rather than £1.10 on the river!

 

[cmyers_uk]

Re: gas or diesel

Just to back this up Mobile took a BMW engine ran synthetic oil for 1million miles disassembled it and with 2 exceptions, all the engine parts were within BMW specifications. <br />The exceptions were...<br />The No. 2 piston ring end gaps were .004" over.<br />Two con rod bearings were .0008" over."

 

[magster65]

Re: gas or diesel

Ah, the age old question.<br />As long as you don't mind going a little slower, (IMHO) without question, go for the diesels. Having owned a few bigger boats I'd say anything over 10 000 pounds needs a diesel(s). Twin gas is expensive to run when you open up the throttles. The cost takes the fun out of it and the boat will end up sitting at the marina... it happened to me. <br />I've seen a 120 hp Ford lehman diesel (32' Grand Banks single screw) running perfectly with 9000+ hours on it. Yep, 9000+. It had a slow cruise at 7 but only used about 1 gph. The twin gas will use 4 or 5 gph at that speed. I have a 26' Tolly that'll cruise at 20 mph but never do. The journey is always more entertaining than the destination so I cruise slow... relax, turn the music up a notch, maybe grab a bevvy... and enjoy the ride. I'd trade in my 330 hp (7.4) Merc. for a smaller diesel any day!<br />Happy Yachting <br />One other thing, resale, the boat is worth more powered by diesels.

 

[DJ]

Re: gas or diesel

180 hours as opposed to 550? That's a more a question of the care each has seen.<br /><br />A gas should run 2000+ if meticulously maintained and is fresh water (closed system) cooled. <br /><br />A diesel, who knows, the sky is the limit.<br /><br />I'm not a big fan of Cummins engines. I am going to asssume these are "B" series engines. One has to remember that the B series is a parent bore engine thus cooling system maintenance is paramount. Have the cooling system(s) checked for thier Ph reading. Compare that to what the local Cummins distributor recommends. If the Ph is off, run from those diesels the damage will have already been done. The B series was also prone to head gasket issues. It becomes more of an issue with poorly maintained cooling system(s).<br /><br />While you're at it, draw oil samples on each.<br /><br />If the diesels check out OK, enjoy them. Maintain them and they will be good for a long time.

 

[karrick]

Re: gas or diesel

Cummins Marine Group <br /><br />grimreaper, <br />You can check out the above link and read up about the Cummins marine applications. IF you click on the FAQs, your question on diesel vs. gas is explained. You can also find local dealers that could give you some advice or service if needed. <br /><br />DJ, <br />Sorry about any bad Cummins experience you have had. I have to be a fan of their engines since they give me a check every week. I am somewhat removed from the marine business since I work mainly with heavy duty and automotive.

 

[mattttt25]

Re: gas or diesel

diesels. gasoline on a 38 will kill you.

 

[roscoe]

Re: gas or diesel

Seen diesels with 25,000+ hours on them, and still pulling 80,000# down the highway.<br /><br />Granted, these were not marine engines.

 

[snapperbait]

Re: gas or diesel

One other thing to consider... Maintnance cost on diesels will be higher, period... Parts cost more, they hold more oil, use larger filters, fuel quality must be watched over more carefully thus filters cost more.. Just a few examples<br /><br />Like DJ says, ph and oil samples, if the engines check out ok, go for it...