MarkRobinson

The motor will probably sit too close to the rear of the boat to allow enough space to divide & plumb to both turbos, unless I Pull the turbo to in front of the engine, then divide...that's my basic concept at this point.

Hole shots are what kill your outdrive, just like holeshots at the strip kill the 951 transaxle. They run these boats on outboards, inboard/outboards (mine), & jet.

txhokie4life

Yeah -- but he'll get them in the braking zone and out corner them.......

txhokie4life

Noticed i have a complete engine you may grab as well.

Will be out there at a minimum of Saturday morning -- trying to get the RSR to the track this weekend.

m

MarkRobinson

Here's my idea for the single turbo: WG's would be plumbed back into the exhaust, though would probably run a single 46mm. This plan would allow for lots of post-turbo water injection for cooling.

Motor should sit low enough...will know in a few weeks.

Mark

ian

I love this project.

Keep up the good work.

MarkRobinson

If going twins, here's my path: much prettier.

Paulyy

My answer

twin GT2056 turbos with internal wastegates (cheaper) unless you want 2 external 38mm gates.
Boosted from 20 psi to 25 psi on e85 & with cooling from the water you should be able to get 450HP

like the stock 951 exhaust manifold how it goes 4 into 2 then 1 you get cylinders 1&4 to 1 turbo and 2&3 into the other turbo.

Dougs951S

I like that idea Paulyy. Those would spool up very quickly and would give you the torque you need. Pulling strongly all the way >6000 rpm isnt really a consideration in this build either so I feel that the added simplicity and reduced cost of the internal gates would make those a great choice.

Adker

How are you going to cool the exhaust pipes? Most boats have water jackets on the exhaust manifolds to keep temps down inside the engine compartment. After the gas is cooled, it goes into a normal exhaust pipe to exit the boat. With a turbo, you need the hot gas to spool up the turbine so the manifold can not be cooled. To me, this seems like a hard problem to solve.

If it were my build, I would be looking at using a supercharger to make the boost because it fits the application better. I would size the prop to run at a max of 4-5K RPM to run in the higher torque range of the engine.

I do like the fact you have a goal and are forging ahead. I have replaced all the stringers in my boat and I know that it is a very hard/time consuming job and you have to love the boat to even think of doing it. Good luck.

MarkRobinson

Yeah the wood replacement is a pita: I don't mind the work, just messy & uncomfortable. :/

Dunno about turbo/exhaust cooling yet. Might just double or triple wrap the exhausts & inject water post-turbo: dunno yet. I have great welders at hand so not worried about it.

My hp goal is upwards of 550-600hp: I want to clear 80mph with this boat, so the drive, hull, and motor will all need to be customized. Fun!

Mark

MarkRobinson

Ok, I have my donor motor: '86 951 out of a running race car, fresh oil change, ran it last weekend for 45m prior to pulling it out on Saturday. Ready to be rebuilt & prepped for long intervals on-boost at 45-5500rpm. Besides windage tray, fresh bearings/seals/rod nuts, anyone have any other advice for a motor that'll see generous boost at long intervals?
I plan to have the head and block decked to ensure they're perfectly level.

Thanks, Mark.

eman930

Cooling lots of cooling, big oil coolers, Big intercooler, maybe even oil squirters for the pistons

MarkRobinson

Using 69 degree lake water for water-to-air/oil/coolant exchangers, shouldn't be a problem there.

Squirters! that's what I had forgotten: is there a thread/source to add squirters to a 2.5l 951 motor? My recollection is that they were only for the 3.0 motors.

Mark

odurandina

2 things....

1. last i heard, lake Travis is down what ~90 feet from a few years ago?

2. how many hours did the motor last?

MarkRobinson

Water too low to launch any boats, motor was loaned to a friend to get his car sold, so will get another motor from him next year when I'm ready to install it. Still working on the boat, rebuilding completely. Fun stuff.