stevesxm

adam,
if you are an engineer and designing a very expensive boat for a client, don't you think you should be using real data from the engine supplier from his BSFC numbers from the dyno work instead of some off the cuff meaningless numbers from a web site forum somewhere ? where are you getting your stress and strain numbers , the sunday comics ?

mr3dman

Oh no you diiin't!! LOL and a great point

Adam Younger

whats your problem?

I use all the data possible - as it happens Mercury are very lacking in real hard figures as most people in the trade know....

onesickpantera

iTrader: (1)

X2

wrinkleface

Actually if I member right, retail 4 a 1350/m8 drive is a bit over 200K!!

tcelano

A BSFC of 0.5 lb/hp/hr should be about right, although it's possible the Merc could do a little better, as it's not having to roll a supercharger. It would be nice if they'd publish the curves. They are readily available for all the diesels I work with.

0.5 * 1350 / 6.5 lb/gal = 104 gal/hr per engine @ wot.

On my dyno runs earlier this year with an 572EFI supercharged setup, we were able to keep the A/F around 12.5-12.7, and get BSCF down to 0.45, until it got up over 4500 rpm. Then it worked its way up to 0.50 at 5900 rpm, but we pushed the A/F down to 12.3 running flat out. This setup kept the EGT's around 1400F.

drpete3

I thought it was supposed to have about the same economy as a 1200

stevesxm

if you are the designer and an engineer that didn't get your degree at sears, wouldn't you think to take the real data from the the real engines that you are going to run at the various avg percentage throttle usage for load vs time that you know from real world data acquisition from like types in the past and calculate the area under those curves to get to an answer that was something more than inspired guesswork. ? i mean really... sitting with a clean sheet of paper designing a client boat and you are using off the cuff , non specific data. if you are going to do that and the basis of the question is " what size fuel tanks to run," why not just bypass the question entirely and just run what size fuel tanks everyone else does ?

the object of design is to arrive at an original solution that creates a competetive advantage. that starts with having real data from the engines that are actually going to go in the boat.

the brits would send "engineers" over to work on the race cars. it was a rare occassion when one could justify a conclusion with any genuine calculation or engineering basis. the feeling for the most part was that british airways was giving away engineering degrees on the flights over along with little plastic wing sets to the kids.

Adam Younger

Would be interested to know your background Stevesxm as I'm sorry but I don't know you.

Your messages seem to be more points scoring exercises and actually don't really add up.

I mean "the brits would send "engineers" over to work on the race cars. it was a rare occassion when one could justify a conclusion with any genuine calculation or engineering basis. the feeling for the most part was that british airways was giving away engineering degrees on the flights over along with little plastic wing sets to the kids." ........

The internet can be a great place and a way of sharing information but there can be so much negativity...

PokerRun388

Exactly, well put. Anyone buying 1350s is very wealthy and isn't concerned about gas money..