Ecotec Motor going into a boat

[delcowizzid]

if the wiki is right should be 193hp

 

[4bait]

Bit of help please

Trying to run the original Mercruiser Tacho and have connected it to the brown wire that normally sits inside the mudguard when the motor is in a car.

However I can't make it work the Mercruiser tacho.

The brown wire is good all the way back to the DFI module. The genuine GM manual it says that this wire is for I/P tacho's (I guess I/P stands for independent or something).

Now I am curious will this wire run a standard aftermarket Tacho? When I put the same motor in the Hilux I used an adapter to convert the signal but this may have just been to run a 4cyl Toyota tacho can't remember.

I would like to run the Mercruiser tacho if I can especially since I just made up a new dash panel for it to fit in.
If I have to replace the Tacho then I will need to make another new dash Grrrr.


Also another concern is that the motor will run with the oil pressure switch disconnected, I assumed that since the fuel pump runs through the oil pressure switch that the motor should not run while it disconnected? I have double checked the relays and wiring etc and all is good

Have also checked our stock VR and also the Ute and they both also run when disconnected so now I’m a little confused as I thought the oil pressure switch was a fail safe to cut the fuel pump.

Cheers Andy

 

[delcowizzid]

oil pressure switch is a backup for running in limp home mode and if the rest of the pump circuit fails relay etc .the tacho can be a problem if its made for a 12v signal lots of aftermarket ones have trouble working on the v6 does it move at all then cut out when the revs come up or nothing at all

 

[4bait]

oil pressure switch is a backup for running in limp home mode and if the rest of the pump circuit fails relay etc .the tacho can be a problem if its made for a 12v signal lots of aftermarket ones have trouble working on the v6 does it move at all then cut out when the revs come up or nothing at all

It does nothing at all. Have even tried changing it between 4,6 and 8 cylinders just to get a response from it.

Cheers Andy

 

[4bait]

is there any particular type of tacho that work well on these?

the hole I have is 3.5 inch or about 90mm and prefer to find one that doesn't go over about 7000rpm. boat will be set to around 4200rpm full throttle.

All the ones I have seen have those stupid shift lights and wanky stuff on them, as if people don't know when to change gears and need a stupid light to tell them when to change, not only that but there are no gears in a boat LOL.

I would be looking for something old school.

Cheers Andy

 

[vn_v6]

the shift lights are detachable, and autometer sell some without them, and they look old school to

 

[delcowizzid]

did the tacho work with the last engine.ide maybe try earth the tacho negative to the engine directly and see if it has a better time also try the green spout at the dfi .sometimes you need to run a 10k or 480 ohm resistor or similar inline yo get them to red over certian revs thats why i asked if it moved at all i can find out the exact resistor value if need be

 

[4bait]

yeh it worked fine on the last motor but it was an old 12 volt ignition with coil and points set up not electronic.
I have just purchased a new Tacho off Ebay coming from New Zealand.
It's the correct diameter for the hole, is all black face with no extra Gizzmo's on it so will see how it goes when it gets here.
might keep playing with the other one in the meantime.

cheers Andy

 

[4bait]

Ok with the boat motors they need what is called an interrupt switch, which basically kills the motor momentary by shorting the coil to ground. This is to take load of the prop so it will return to neutral.

Without the interrupt it is very hard to get the gears to go back to neutral. To achieve this I have wired up a switch to the gear selector cable so that when activated it triggers a relay and cuts power to 3 injectors. This drops the RPM briefly to about 300rpm and is just enough to take the load of the prop and get the thing into neutral. The switch and mechanism is off the original engine and it simply just shorted the coil to earth hence the reason I needed a relay in the circuit to operate it on the ecotec engine. They are designed to work only when disengaging gears and not engaging

Heres a pic of the water proof box I put in for the computer and stuff for those who are interested.


I used an Ice box so it is also insulated from heat and cold and it is tucked up under the transom behind the rear seat.
I have a little bit of Glass work to tidy it all up a bit more.

Cheers Andy

 

[4bait]

Ok so the BOM got it wrong and the predicted 30-knot winds and 3 meter waves didn’t arrive.

So I finally got to do my water test and I must say I was very happy with the results.

First off I had an old 19p 3 blade prop on and found the thing didn’t have enough thrust to steer the boat properly at idle, Which is strange because the old motor had a 4 blade 17p so their must be a slight gear ratio change there.

With the 3 blade prop it still went well under high revs but it did want to rev higher than I liked, also hole shot was awesome, in fact too awesome LOL.
Piece of advice don’t try this without securing everything in the boat first LOL, I went from Idle to full throttle and everything that wasn’t tied or bolted down in the front of the boat ended up in the rear of the boat in a milli second LOL

Given that I headed back to the ramp and swapped the 19 p prop for a 21 p 3 blade prop and headed back out again.

This was heaps better, Hole shot as expected was down a little from before but still pretty good and WOT at around 4700 rpm doing 65kph 35 knots. This is a 10kph improvement from the old engine and I think there is still heaps of room for more improvement.
I’m Still running the standard Holden computer chip at this stage as it gives me a starting point to change things, but over all I think the standard tune is pretty good and fairly well suited to the boat.

Exhaust manifolds at full noise stayed nice and cold and basically everything did what it should be doing.

I think the prop may have a slight slippage in the bush as the motor seemed to intermitantly rev slightly higher for no reason and the prop nut was loose when I got back home.

I would also like to make the whole thing a bit quieter and will be putting some extra sound deadener foam in the engine bay, It is better than the old 470 motor for noise but again there is room for improvement.
Why do cars run pretty silent at 3000rpm and boats sound like a rocket ship LOL,

Here is a bit of video looking over the transom while under way Please excuse the shoddy camera work as it is hard to shoot video and drive a boat at the same time LOL, (Lucky there isn't a law against it yet)

Cheers Andy