Powerplant swap Bertram 20

krisnowicki

Lieutenant Junior Grade
Joined
Jul 11, 2007
Messages
1,172
Re: Powerplant swap Bertram 20

get some tips and run thru hull put the holes right at or slightly below the water line and then it will be quiet rumble at idle and a nice roar on the go. My new boat has them out the side and below the line and I like it alot
 

26aftcab454

Lieutenant Commander
Joined
May 12, 2009
Messages
1,510
Re: Powerplant swap Bertram 20

good luck and such a sweet looking boat. Once it is up and running I am sure you will be pleased.
 

arfaname

Seaman
Joined
Jul 1, 2005
Messages
71
Re: Powerplant swap Bertram 20

Gda Aldo,

Mate i will chase down Mill tomorrow. I wonder if he can weld to cast ally?

I am going to surprise you very soon with some pics of the old girl up and running again in all white. The fella that bought it from me has just gotten her back on the water and i would think this weekend may be the first launch. He still has repairs to do on the hull but he seems happy enough to use it as is somewhat for now.. eek..

I have had a fair hand in the rebuild along the way even after the sale as he is a nice fella and deserves a hand.

Capt...

yeah I have looked at the thru hull exhaust but would hate to "become known" as the bloke with that bloody loud boat. I know they sound great at first but im concerned after 3 trips I would be over it.

Your right on the missing trim.. so be it..

As for the fuel pump, you wouldn't believe it by how little it misses by. Shame.. but true.



Progress today.

I managed to find some engine mounts from a ski boat parts supplier. They required some "adjustment" and we fabricated up some angled mounts to sit them on. They have come up really well. We have started looking further at exhaust options, high mounting the alternator and blanking off the fuel pump.

Slow progression day but were getting there and most importantly IT FITS.

edit: I should add here that due to my work commitments i have a mechanic mate of mine doing a lot of the work during the day but like a kid with a new toy I am struggling to stay away and concentrate on my work.. lol..
 

captmello

Captain
Joined
Jun 30, 2008
Messages
3,848
Re: Powerplant swap Bertram 20

Capt...

yeah I have looked at the thru hull exhaust but would hate to "become known" as the bloke with that bloody loud boat. I know they sound great at first but im concerned after 3 trips I would be over it.

Your right on the missing trim.. so be it..

As for the fuel pump, you wouldn't believe it by how little it misses by. Shame.. but true.

FWIW, I agree on the thru hull's, they can be a bit obnoxious. However, what's nice about a boat with good torque and horsepower is you don't have to run the engine at 3500 rpm all the time. My boat, while weighing less than yours, will plane and cruise at 2600 RPM and still hit 4400 @ WOT. If I had trim tabs, it would cruise at ever a lower RPM. At 2200-2600 RPM the engine is very quiet. Whatever way go, Its going to be nice.:)

With the electric fuel pump, you just have to make sure to wire it safely including an oil pressure cut out switch.

Keep us updated!!!
 

captmello

Captain
Joined
Jun 30, 2008
Messages
3,848
Re: Powerplant swap Bertram 20

Capt mello, yeah unfortunatly I did think I was getting power trim however in hinesight its not the worst outcome as i dont have to change the transom shield.

Re: transom shield, If you plan to reuse the transom shield currently on the boat, and you decide to install the Y pipe, make sure your current transom shield has Idle relief ports on both sides of the shield. I can't tell from your picture if your current drive has two reliefs or not. They are on either side of the exhaust port coming through the transom shield.
 

krisnowicki

Lieutenant Junior Grade
Joined
Jul 11, 2007
Messages
1,172
Re: Powerplant swap Bertram 20

I wonder what would happen if he used a v 8 y pipe with only one relief.
 

captmello

Captain
Joined
Jun 30, 2008
Messages
3,848
Re: Powerplant swap Bertram 20

I wonder what would happen if he used a v 8 y pipe with only one relief.

I don't know.

I'm not into modifying things as I'm not trained in such work. However, this poster doesn't seem afraid of a little modification.:D

Just wanted to point it out.
 

Paul Ryan

Petty Officer 2nd Class
Joined
Oct 16, 2009
Messages
125
Re: Powerplant swap Bertram 20

Paul, Mate no problem getting a couple of good pics for you once its all back together. Right now I just need to concentrate on getting her right but sure thing in a couple of weeks.

Thanks Mate!!!! I know your boating sesson is full swing right now so keep on plugging at it. Works look great. Get er Done!!! :D
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: Powerplant swap Bertram 20

Hi Afaname,

I also have an old Bertram 20. Originally with a Mercruiser 165 it did about 30 knots. I have since re-powered it (twice!) and it now has a V6 EFI (producing 220hp at the prop) and she tops out at just over 43 knots! Get ready for the ride of your life!!! Real shame about the power trim, I find that I use it more than the throttle.

Cheers,

Chris.......
 

arfaname

Seaman
Joined
Jul 1, 2005
Messages
71
Re: Powerplant swap Bertram 20

Capt,


Idle relief port????

To be brutely honest with you, I have no idea what you mean. I have looked at mine and see no such beast that im aware of.

What would it look like and whats its function?


aaaaaaaaaaaaaaaaannyway i have bitten the bullet and decided that It will be no easy feat to have a Y piece fabricated that will last the test of time. Nobody seems confident that stainless is the answer. I have been concerned with restricting the exhaust by feeding it through the leg and also concerned that the fabricated Y piece may "let go" and fill the boat with water.

Aldo, I did speak to Mill however he is now only doing 4wd stuff and was in no way interested. I mentioned your name and he remembered doing something on your camper??

We managed to shave out a scallop in the upper edge of the stringer to allow fitment of the original mechanical fuel pump. Im much more at ease with that now.

Thanks for the tip on the cutout using an oil pressure switch. Good idea however I wont need it for this one now.

Pic of the fab'd engine mounts in place.


emptybilge350.jpg
 

captmello

Captain
Joined
Jun 30, 2008
Messages
3,848
Re: Powerplant swap Bertram 20

Capt,


Idle relief port????

To be brutely honest with you, I have no idea what you mean. I have looked at mine and see no such beast that im aware of.

What would it look like and whats its function?


aaaaaaaaaaaaaaaaannyway i have bitten the bullet and decided that It will be no easy feat to have a Y piece fabricated that will last the test of time. Nobody seems confident that stainless is the answer. I have been concerned with restricting the exhaust by feeding it through the leg and also concerned that the fabricated Y piece may "let go" and fill the boat with water.

Aldo, I did speak to Mill however he is now only doing 4wd stuff and was in no way interested. I mentioned your name and he remembered doing something on your camper??

We managed to shave out a scallop in the upper edge of the stringer to allow fitment of the original mechanical fuel pump. Im much more at ease with that now.

Thanks for the tip on the cutout using an oil pressure switch. Good idea however I wont need it for this one now.

Pic of the fab'd engine mounts in place.


emptybilge350.jpg

My understanding is that the Idle relief port allows water to drain from the Y pipe in case water starts to back up in the outdrive exhaust system while at idle (lower exhaust pressure), to prevent water backing up the y Pipe.

In your pic, if you look at the transom shield, at the lower hole (exhaust port) there is another smaller hole right next to it, to the left in the pic. that is an idle relief port. I assume you do not have another idle relief to the right. Can't tell from the pic. Does the new transom shield have one or two idle reliefs?

If you look at this link, the drawing shows a single idle relief port at the base of the Y pipe. That Y pipe would fit a single idle relief transom shield, as long as they are on the same side.

Note part #29 is a rubber hose that comes from the idle relief and out the other hole in the transom shield. Also note the quantity calls for two of the small hoses.

http://www.volvopentastore.com/Connecting_Components_Aq_Drive_280/dm/*******.147735930--**********.216917193--store_id.366--view_id.325226

My Y pipe and Transom shield have two idle reliefs, one on either side of the exhaust port.

I've seen some boats (four cylinder) with no idle relief but still had the hole in the transom shield, however plugged.

All of this info may or may not be of any use, however if you begin searching for a Y pipe, keep this info in mind.

Pic of the fab'd engine mounts in place.

Mounts look nice. I do want to point out a couple of details. It looks like you have center mount bolts which makes me think your missing the lower feet for the motor mounts. Have a look at this photo (sorry its so small) may have to zoom in.:rolleyes:
motormount.jpg
[/IMG]

Can you see the red motor mount behind the fuel pump?

That mount allows you to adjust the engine height at the center bolt. I'm sure you can figure something out, but you may want to make it so you have some adjustability without having to lift the motor to shim. I'm also a little nervous about mounting the motor to the side of the stringer. I think I'd like to see some support down on that metal cross member below if thats possible.

Real shame about the power trim, I find that I use it more than the throttle.

The only thing power trim would help you with is a hole shot.:confused:
If the mechanical lift is functioning properly, you can get by fine without power trim.
 

Dunaruna

Admiral
Joined
May 2, 2003
Messages
6,027
Re: Powerplant swap Bertram 20

Mil made me a new SS poo tank for my houseboat. I've got a project GU on the go at the moment and he is fabricating an intake snorkel for it.

I think the 4X4 stuff is very lucrative for him.

On the subject of mounts, are you aware of Luxford marine in Dandenong? They have a good stock of after market mounts for i and i/o.

www.luxfords.com.au
 

arfaname

Seaman
Joined
Jul 1, 2005
Messages
71
Re: Powerplant swap Bertram 20

Thanks Capt,

Ya know I have never seen a shield yet with the relief ports you mention. My port is blocked off and I believe my last boat (that ran a 302w installed by a real good lookin fella named aldo) didn't have them either. I understand thier function now and can see the advantage however it wont be an option now that we have gone straight through.

As for the mounts, unfortunatly we have been very very restricted in what we could do because we only had a bilge of 530mm to work with. Everything is nowmally designed for a 24 inch hole minimum. I have the stolls for the mounts hovever there was no way to make them fit. The mounts we have fab'd will allow for adjustment if required by way of adjustable nuts if required.

What I am a little concerned about is how critical the spacing is on the alignment tabs between flywheel cover and transom shield. It is very close but I am concerned it may be a mm or two out. is this a problem?
 

Paul Ryan

Petty Officer 2nd Class
Joined
Oct 16, 2009
Messages
125
Re: Powerplant swap Bertram 20

As long as the 3 alignment tab gaps are within 2 mm of each other your ok.

Agreed...When I installed my powerplant a couple months ago I got the 3 tab gaps at 2mm of each other. Now with a few test runs under my belt I have seen no ill effects. I have checked the bellhousing and plate several times. The marks have not moved and the gap is still the same has when it was installed. :)
 

arfaname

Seaman
Joined
Jul 1, 2005
Messages
71
Re: Powerplant swap Bertram 20

Well its been a long time between drinks gentlemen but we have progressed. The engine is in and running and the boats been wet twice. Excluding a little hickup with the alternator it has run flawlessly.

In the end the pipes became thru hull as the y piece from VP was going to far too wide for the bilge and room beside the bellhousing was not available.

So the numbers are!!!!!!!!!!!!!!!!!!


She idles at a sweet 900rpm and slides into both fwd and rev very smoothly (best ive owned)

she jumps out of the hole effortlessly and motors on plane at about 2500rpm.

At 4500rpm its doing a touch under 50km/h

at 6500RPM


surprised_smiley.gif


ITS DOING 75KM/H.

Now im cery concerned about the revs as its supposed to top out at 4400rpm. I will be checking the tacho this week to ensure it is right.

I have taken the serial number form the upper box on the leg to get the ratio but cant seem to find any info.

if somebody would know where to find it this is the serial: PZNR28008389B

So once I fix the ratio or prop im sure it will be a real pleasure to drive.

Photos coming, had some dramas uploading pics lately.
 

captmello

Captain
Joined
Jun 30, 2008
Messages
3,848
Re: Powerplant swap Bertram 20

Great to hear you're on the water!!!!

The Idle should actually be down around 650 with the drive in gear. Around 725 in neutral.

It sounds like your Tach is set up for the original 6 cylinder. Check the back of the tach to see if it can be switched to 8 cylinder.

Also, keep in mind, you've got a 290 upper on a 280 lower so the serial number on the upper won't tell the gear ratio since the gearing is in the lower unit.

I guess I'd hook up a shop tach to the engine and compare it to the boat tach.

Let us know what you find.:)
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Powerplant swap Bertram 20

It sounds to me like you have the wrong gear ratio. A prop change of one set size will only get you 100 to 150 rpm difference, and you have a 1000 difference. There isn't that many different prop set sizes.
The gear ratio for the drive is usually stamped on that plate that had the SN stamped on it. You can also pull the props off and the anode and the gear ratio is usually stamped on the housing. If someone hasn't changed the gear ratio or changed parts.

You can also put it in gear, turn the engine by hand till the props start turning, then turn the engine and count the revolutions you turn the engine to turn the props 1 complete revolution. You should have a 1.95 ratio, or almost 2 full turns of the engine for one turn of the props.
 

captmello

Captain
Joined
Jun 30, 2008
Messages
3,848
Re: Powerplant swap Bertram 20

It sounds to me like you have the wrong gear ratio. A prop change of one set size will only get you 100 to 150 rpm difference, and you have a 1000 difference. There isn't that many different prop set sizes.
The gear ratio for the drive is usually stamped on that plate that had the SN stamped on it. You can also pull the props off and the anode and the gear ratio is usually stamped on the housing. If someone hasn't changed the gear ratio or changed parts.

You can also put it in gear, turn the engine by hand till the props start turning, then turn the engine and count the revolutions you turn the engine to turn the props 1 complete revolution. You should have a 1.95 ratio, or almost 2 full turns of the engine for one turn of the props.

I think you've got this mix up with another thread perhaps Don.:eek::rolleyes:

The OP shows Pics of a 280 single prop with a 290 upper. In which case he'd need a 1.61 gear ratio.

Check the tach first. I'm sure going from 6 cyl to 8cyl is part of the problem. Hopefully he's got the right ratio.
 
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