Gratuitous Personal Request

Lease

Calling all motor people!

I have this boat. It weighs exactly one tonne. The factory advertises, and other users confirm, that a standard 50hp Tohatsu ('95 model) will take it to 20 knots. Indeed, it will only degrade one knot for every 50 kilos of extra weight, they say.

My experience is somewhat less than this, however. The best I have managed is 13 knots. Now it should be said that the thing does need a carby overhaul as there is some gunk in them after a period of prolonged storage. This is only holding the engine back from its potential maximum 5,800 rpm, to 4,900 rpm at 13 knots. It is hard to imagine that I'm going to get the extra 7 knots from 900 rpm, when I finally shell out for the overhaul/service.

When I bought the boat - and this is important - I had some work done on the motor that cost a bundle (which is why the other aint been done yet), and at the same time had the compressions checked. These are all still at the factory delivery tolerance, which is encouraging, and not where the performance problem is. Oh, and if it is important to know, it is oil injected, not pre-mix.

I want more power, so here comes the questions:

1. I notice that Shell is advertising a new 100 octane unleaded fuel. This has 5% methanol. I already use 97 so will the higher octane stuff provide more power? Will the ethanol cause me problems with carbies/reeds, etc?

2. Do these carby things come with an ECU of some sort, and can you change the ECU for more power?

3. What can I do (within reason) to increase the power out of the engine?


Why don't I get a new engine?

Well, they cost an effing fortune, that's why!

Apart from that, this is mainly a sailing boat, and I can cope with 78kgs hanging off the back - just. 150kgs for a 90hp four banger would make me die of embarrassment.


Come On - Help Me!

[Edited on 15/2/2006 by Lease]

SuperRoo

Mmmm, interesting conundrum Lease. A right pickle.

I would say you probably do not have an ECU, and that 100 octane is for “modern”
Fuel Injected engines only.

To answer your problem, it sounds like you have a bent thingamajig, causing the watchamecallit to restrict its vertical lift, thus causing what is referred to as dohickey from completing the stroke that is required spark the thingamabob. Get yourself a new widget. I’m sure this would solve it. Other than that get a paddle.

Telstar

Mmmm, interesting conundrum Lease. A right pickle.

I would say you probably do not have an ECU, and that 100 octane is for “modern”
Fuel Injected engines only.

To answer your problem, it sounds like you have a bent thingamajig, causing the watchamecallit to restrict its vertical lift, thus causing what is referred to as dohickey from completing the stroke that is required spark the thingamabob. Get yourself a new widget. I’m sure this would solve it. Other than that get a paddle.

Don't forget the flux capicitor fluid.


Seriously I unfortunetly have no experience with boats with engines but I totally understand the new engine cost.

Good Luck.

viges

Have you tried winding up the elastic band?

Dr_Spin

I heard of a similar case.

A helpful observer told the new boat drivers to flaot the boat OFF the trailer, and .....that solved the problem.

Sorry lease, my experience is more with 18,000 DWT transitting at 15 Knots, which we're hoping to offload a 11,000 tonne platform onto an offshore jacket come dawn tomorrow.

We don't want wind at all in this case, just plain sailing.

Spin

GrecoMinardi

Have you tried winding up the elastic band?

lol....:hehe:

Clown

1. I notice that Shell is advertising a new 100 octane unleaded fuel. This has 5% methanol. I already use 97 so will the higher octane stuff provide more power? Will the ethanol cause me problems with carbies/reeds, etc?

Snce you only have a carb tiping in higher octne fuel won't make much of diiference unless you advance the ignition timing (or its already detonating). Ethonal doesn't do enginne damage per se. It damages certain fuel lines (kina forget which type) but I wouldn't risk running it unless your 100% sure.

2. Do these carby things come with an ECU of some sort, and can you change the ECU for more power?

Carbs are mechanical, ECU's are electronic. You can't have both controlling fueling.

3. What can I do (within reason) to increase the power out of the engine?

Convert to programmable engine managment (really not that expensive using an old fuel-only computer), regrind the cam to something bigger, install extractors and a 2inch exhaust. If that doesn't work, then run it on c16.




[Edited on 15/2/2006 by Clown]

MCSF

Carbs are mechanical, ECU's are electronic. You can't have both controlling fueling.

Actually FoMoCo did a comp controlled variable venturi carb back during the death spiral of the good old bug sprayer - failed miseably.

Convert or die I say.

To injection that is.