P25 Inboard

larby · 27-05-2009, 11:05 PM

Me again,

I've been searching away and can't find any info on this one... Were there ever any P25's with inboards? I'm pondering on the idea of a P25 with a single large V8, coupled to a speedmaster or similar, or maybe preferably a surface drive? I'm thinking ski race stylee with exposed headers etc, something a bit different!
I see Scand has coupled a P21 with a VW diesel and a surface drive before with some success?
I know it's a bit 'out of the box' but i reckon it could work, i could well be totally wrong though, I know there'll be people on here who know far better than me!

James

Captain Chaos · 27-05-2009, 11:56 PM

theres a chaudron 25 with a supercharged smallblock in malta

PerformanceDodge · 28-05-2009, 12:35 AM

That sounds like an interesting project, I built a 27ft Sharp about 10 years ago from a bare hull and deck. Rumour has it that the Sharpe was based on a P25 hull lengthened. It was built as a pleasure boat with crawl in cuddy and slightly on the heavy side but it was excellent in rough sea's. I used a 200 Mariner outboard and it achieved around 40 knots. I learned a few things from it. Really it could have done with 300hp to make it a bit more exciting. The other thing I learned was that it quite easily drank 150 liters of fuel an hour. I'm thinking about a new project. something that will achieve around 55 knots, will handle a bit of rough sea, and something that does not break the bank every time I take it out and have come up with the following idea. Cougar 225 Honda 26 ft hull, speed master stern drive and Mercedes E320 diesel engine. I have a E320 Estate, it has 3.2 litre straight six diesel turbo engine that produces 200bhp and is chipable to 270bhp. If I really cane it and its quit quick it is impossible to get it below 30mpg which is impressive for a 2 ton car. Its relatively high revving modern common rail diesel. I think it could be a good combination. The other engine that may be good but are still quite expensive to get hold of is the later C320 engine. This is a 3.2 litre V6 all aluminium diesel turbo and produces 300bhp standard, I think they can be chipped to around 375bhp reliably. Just wonder if any of the more experienced boat builders have any thoughts on this combination or useful advice.

David

Captain Chaos · 28-05-2009, 12:50 AM

its a big block:

http://www.thinkyachts.com/listing10...dron-25-yacht/

larby · 28-05-2009, 07:47 AM

Awesome, so it could work in theory then, and if i were to use a phantom hull i know of (which i believe is kevlar) then it wouldn't fall apart around me either!
I wonder what difference running a surface drive would make? I just love me tail too much!

James

dowdy · 30-05-2009, 08:09 PM

Quote:

Originally Posted by larby

Me again,

I've been searching away and can't find any info on this one... Were there ever any P25's with inboards? I'm pondering on the idea of a P25 with a single large V8, coupled to a speedmaster or similar, or maybe preferably a surface drive? I'm thinking ski race stylee with exposed headers etc, something a bit different!
I see Scand has coupled a P21 with a VW diesel and a surface drive before with some success?
I know it's a bit 'out of the box' but i reckon it could work, i could well be totally wrong though, I know there'll be people on here who know far better than me!

James

Will be soon

steve h · 31-05-2009, 09:16 AM

Quote:

Originally Posted by dowdy

Will be soon

if you look at transom you will find where the mk3 drive was fitted in 1991 ,its already been down this route,

PerformanceDodge · 02-06-2009, 12:39 AM

This is a link to a Marshan that was converted to from outboard to inboard Diesel

http://www.youtube.com/watch?v=qoLJ9RPXB2U

PerformanceDodge · 02-06-2009, 12:53 AM

This would be a good engine for a ski style boat Chevy LS7, all aluminium 505bhp out of the crate. Shop around and you can pick one up new for around 6k. Can find full specks at link below. Would make a very quick P25

http://www.ukusaengines.co.uk/ls_engines/ls7.asp

PerformanceDodge · 02-06-2009, 01:06 AM

Here is a link to surface drives, LS7 is dry sump too, so could mount very low in boat.

http://www.arneson-industries.com/pa...ucts&id=drives

dowdy · 02-06-2009, 06:50 AM

Quote:

Originally Posted by larby

Me again,

I've been searching away and can't find any info on this one... Were there ever any P25's with inboards? I'm pondering on the idea of a P25 with a single large V8, coupled to a speedmaster or similar, or maybe preferably a surface drive? I'm thinking ski race stylee with exposed headers etc, something a bit different!
I see Scand has coupled a P21 with a VW diesel and a surface drive before with some success?
I know it's a bit 'out of the box' but i reckon it could work, i could well be totally wrong though, I know there'll be people on here who know far better than me!

James

FOOKING ELL larby lad,youve started something now,love the look of that arnson drive,the line drawings look simple enough,yup,know what im going to do now ,post when completed

PerformanceDodge · 05-06-2009, 12:27 AM

Converting from outboard to inboard is not too much of a problem, but setting up a surface drive and getting it right is a bit more complex, this is an interesting thread I found and it makes interesting reading.

http://www.boatracingfacts.com/forum...hp/t-2974.html

This guy has designed his own and splendid job he has done too.

PerformanceDodge · 05-06-2009, 12:27 AM

I also found a few variations and different manufacturers of surface drives.

The Seafury http://www.seafury.com/index.html

DBD Marine http://www.dbdmarine.com

The Docta · 05-06-2009, 06:31 PM

I always thought that hyabusa powered Danza was quite an interesting idea -thats on a home made surface drive.

http://www.youtube.com/watch?v=i3sMe...eature=channel

dont know if the guy ever got anything decent out of it speed wise.

Sounds pretty sweet though!

dowdy · 05-06-2009, 09:02 PM

Cheers for that lads.That DBD300 defo looks the biz,new ground for me this,never done surface drive before,i like doing firsts tho,1st with an alison,1st with a cirrus stilleto,both failures,3rd time lucky.Love me boats

cosworth mirage · 06-06-2009, 10:21 AM

been watching this post ive looked into these subjects a bit over the last few years with all the stern drive troubles ive had the best looking surface drives ive seen are the weismann transmisions hammerhead its a counter rotating surface drive and looks awesome. http://www.weismann.net/Press%20Page...annDuoProp.htm
the ls7 motors are good but i thing the ford modulars looked a better motor
i managed to buy a t50 cammer and its 480 bhp 5.0 litre quadcam all alloy dry/sump/steel crank .there is loads of mods for these engines they use them in mustangs/gt40/and lots of other stuffhttp://www.seanhylandmotorsport.com/modular_crate_engines.shtml

diesel will be a waste of time and money in less its just for cruising
you need to down rate turbo motors for marine use not upgrade but the main issue of the modern diesel is its narrow power band 1750-3750 is its main operating range so you will need to add a gearbox to get any speed and they are only fuel efficant at lower revs and lighter throtle if you rev it hard at full throtle you wont be far of the consumption of the equivalant petrol engine

cosworth mirage · 06-06-2009, 10:24 AM

http://www.seanhylandmotorsport.com/..._engines.shtml

dowdy · 06-06-2009, 03:26 PM

Cheers cossy,one of my concerns sorted,left handed torque,was going to try trim tabs or counter ballasting,that duoprop is one mean looking mother tucker,come on someone,take my 2.4s off me so i can get crackin,need to get out.

cosworth mirage · 08-06-2009, 04:04 PM

problem with there stuff is you need a p1 budget to buy it
volvo dps looks like the best contra rotating option from what i hear there reliable but v24 pilots will know more.
arnesson looks like the best option for single prop but you need g/box and drop box for your boat

bor · 25-06-2009, 07:59 PM

I am converting a p21 into a inboard whit a ls2 corvette engine wich is the little brother of the ls7 ,the engine is know at machine shop to stroke to 408 cid and get's all forged internals and the dry sump system of the ls7 and will make 550hp at the crank .

the drive is waiting new in the box wich is a bravo 1 X 1 to 1:50 ratio with 2 ram hydraulic mayfair steering system .

all parts are on the shelf hoping to start building end of this season ,this because I bought a bad "splash" p21 and have all wood complete out to put new in .

if you start with a project like this make a thread of it and I will your biggest fan !!