Ross: Number 2 diesel is preferred as it has a higher BTU rating than Number 1 and will create some measureable amount of power increase over number 1. Here in Canada we are following the states as to having ultra low sulfur and bio-diesel which from field reports of fellow technicians there has been a problem of deterioration and some clogging of fuel filters with the bio-diesel and the lack of lubricity as the oil gurus call it for the older diesel engines. One has to run an additive in the oil to help out the injection system. Some techs call it two stroke oil in the mix to allow the fuel pumps to not seize up.I run some Stanadyne lubricant recommended by the fuel injection shop I deal with as I run 2 Cummins B models in mine. As for power and correct prop pitch I used the prop calculator which is on line and came pretty close to what I figure the boats performance should be. I run the the 34 foot at around 8 knots to save fuel and flat out at 2400 she does 16 knots with 17/18 cupped props and no vibrations through all the rpm range. With your detroit engines they only like wide open throttle and mass amount of fuel consumption as it is a two stroke and not a four stroke. But running at around 1600 they will be in their torque range and run forever. Even though they are not emissions compliant , they were a great engine, noisy but can take a beating and keep on ticking.
Regards Roger PS I have talked with you before on your detroits ----- Original Message ----- From: Ross Robertson <[email protected]> Date: Monday, October 4, 2010 8:42 am Subject: [UnifliteWorld] 38C - 6/71NA Performance data. To: [email protected] > > Hi, > In the 38C performance spec I have down loaded, it states Cruise > --19 knots. Max Speed 22 knots. > This I assume is with the almost standard J & T 6/71NAs in the 38Cs > I cannot get near these figures. It is quietly driving me > nuts. The only thing I do well is gulp diesel fuel and > never get far from base....but refueling is easy near a major > port -- Jakarta > Back to the Spec -- for Cruise 19 knots I anticipate this is @ > 1800rpm. WOT 22 kn I guess also is @ 2300 rpm. > I would appreciate anyone, who has good data in this area, > to be kind enough to pass on to me their rpm / speed figures. > Also their prop details - Number (3 or 4 ) and type of > blades ( cup or plain ) pitch and diameter. > Now to the question of power. Here in Indonesia we > have diesel 2, not diesel 1 as in the US of A ( I > think). To take care of the power deficiency I blew > the engines fitting turbo's and inter-coolers. They are > working fine but I see no performance improvement. I > run with just the smallest, 'happy' wisp of white smoke.. The > new engine config' According to the DD manual has at least the > power of the original J & T Nas So next guesstimate is I > have a prop problem... > Thus if a splendid 38C owner is still able to run at the spec > figures in para 1 above, I would dearly like to know his > or her prop dimensions and speeds at different rpm -- clean ( or > dirty) bottom -- > from the boonies -- > Cheers > Ross > > -- > You received this message because you are subscribed to the > Google Groups "UnifliteWorld" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected] more options, > visit this group at > http://groups.google.com/group/unifliteworld?hl=en. > -- You received this message because you are subscribed to the Google Groups "UnifliteWorld" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/unifliteworld?hl=en.
