Cosworth Mirage, Vector Marine XR 24

[danny]

I have had one.
We took it from Northern Holland to Isle of wight and beyond.
Had it for three years and have sold it.

[cosworth mirage]

had the rib out for a couple of shakedown runs
ran it upto 5000rpm and got 40mph with exhaust temp 920 water 70 boost press 5psi
water injection was not cutting in as boost to low
adjusted pressure switch and ran again ex temp 820
checked over boat and changed gear oil and ran the following weekend
ran upto 5500 rpm exh temp upto 890
ran 6000 rpm 50mph exh temp 865
temp starting to drop with higher rpm or pos less drag on hull ,it was a bit to rough to go any faster 3-4 foot choppy swell
back out this weekend will try for 6500 and 7000rpm and record some info
engine setup is for 21psi boost max but it looks like the prop will need some more pitch as its getting to 6000rpm on 60-70% throttle and 6psi boost
will post some pics next week

[Mollers]

Originally Posted by cosworth mirage

had the rib out for a couple of shakedown runs
ran it upto 5000rpm and got 40mph with exhaust temp 920 water 70 boost press 5psi
water injection was not cutting in as boost to low
adjusted pressure switch and ran again ex temp 820
checked over boat and changed gear oil and ran the following weekend
ran upto 5500 rpm exh temp upto 890
ran 6000 rpm 50mph exh temp 865
temp starting to drop with higher rpm or pos less drag on hull ,it was a bit to rough to go any faster 3-4 foot choppy swell
back out this weekend will try for 6500 and 7000rpm and record some info
engine setup is for 21psi boost max but it looks like the prop will need some more pitch as its getting to 6000rpm on 60-70% throttle and 6psi boost
will post some pics next week

Sounds good.

[cosworth mirage]

Went out on sunday for some more trials 6500rpm and 7000 runs, also altered the water injection as well.
nice choppy 3ft sea made testing good fun but seams to affect the speedo,running at 6500-7000 the exhaust temperature has now dropped to 800c, water remains at 70c, boost pressure 6psi, Im really pleased with the progress in speed but also the efficiency shown by the low exhaust temp and the low boost 6psi this is probably about 170hp. We also tried some 3000 to 7000 acceleration runs with higher boost 15psi and it,s a white knuckle ride.
Looking at changing the prop now to increase the speed and load on the engine so i can start adding some more boost and power

[andyxs]

sounds like your cracking along well with it. i would look into a gps for speed as well. far more accurate and a bit less temperamental

[cosworth mirage]

Trying to pace the speed and power increases to keep the boat in a reliable setup,the aim is for a fast boat over longer distances offshore than the ultimate top speed as this is what the xr design excel at,with an evinrude 225 they used to get 52kn if i can get above this then i,d be delighted .

[cosworth mirage]

some more pictures

[cosworth mirage]

new prop on way, gone for a 3 blade cleaver will post some pic,s whilst its still shiny and new

[cosworth mirage]

Had to machine the new prop to clear the rear seal housing so delayed the next test a bit, also changed the seawater filter which kept blowing its lid at speed.
ran the boat upto 5200 rpm and got 45 kn on gps showed 55mph on speedo which looks like the prop is in the ball park, ran with 12psi boost which is around 200hp its still got about 150lt fuel in it so there is more to come.
looking at the engine coolant temp the in temp is 65c and the outlet is 125c which is a bit concerning i think the thermostat is slowing the coolant flow due to the cooling effect of the incoming coolant on the stat so will remove it before the next run.
Also the steering was feeling a bit sketchy and looking at it there is some play in the pivot on the mid section so will do this before next run.
Once these problems are ironed out I will add a bit more boost and then !!!!!!!!!!!!!!!!!!!

[Cookee]

Originally Posted by cosworth mirage

Had to machine the new prop to clear the rear seal housing so delayed the next test a bit, also changed the seawater filter which kept blowing its lid at speed.

Good luck with the boat - I'm looking forward to hear how it all ends up - may even be worth a story in the magazine when it's up and running flat out? Have a look here for a water strainer - there are different options and more than one supplier of course!

[Mollers]

When is the next run? There will be 3 Vipermax out on the Roads for the est of the week.

[cosworth mirage]

pos at the weekend pm your tel no and I will call next run out

[cosworth mirage]

thanks for link on strainer but looks a bit fancy/expensive for my boat/wallet cobination still doing my scrap yard challange bit so i have fitted a 1" y type brass filter assembly from armada hydraulics £17.00 ,thanks for your interest and support Gary.

[cosworth mirage]

Had the centre section from the drive leg of to marine shop for rebushing and ended up with a broken casing .Have now managed to find another casing so just hoping the rebushing goes better this time. just as you think your making progress it goes tits up

[cosworth mirage]

Got the mid section back with new bearings bushes and steering tube,refitted with new seals etc,removed stat and patterned up some parts for external steering ram setup (waiting for parts to come back from machine shop)

Will run with the inboard steering setup for the minute,all the play has gone from the steering and the persistant oil leak i had on the leg seems to be ok.

Hopefully the weather might clear for fri eve (its pi##ing down right now) and the tides good for a evening test.

I going to run upto the 55mph again and see how it all feels then do some longer runs 10,20 then 30 mins at this and keep an eye on things before i add any more boost.

wish me luck Gary

[Cookee]

Brilliant - when it's running as you want it I'll come down and take some piccies and do a story for Sportsboat and RIB if you like?

[cosworth mirage]

thanks John.

[cosworth mirage]

Have had a suspicion that the previous raw water cooling problems might have caused a problem with the engine as it started blowing a bit of coolant out the header tank when boosting over 12psi, so friday carried out a pressure test on the cooling system and discovered the cap was venting out coolant at 10psi and not 20 due to slight pitting on cap seating, so lapped the seat nice and smooth and rechecked and it was now holding 20psi, I left the pressure gauge on the cooling system so we could keep an eye on things when out on the water.
launched that eve about 7.30 and ran 3-4 miles before winding in some boost and the pressure started climing right upto 20psi and then vented so had to slow down and let things settle a little ,feeling rahther pi##ed off i ignore the advise of my co-pilot and thrashed the s##t out of it back to falmouth with water blasting out the overflow and launching off the pilot boat,s wake at about 40kn,s .
got back ok and felt a little better

got the boat back to the workshop and set about stripping the motor,saturday evening fitted new gasket and got it all back together,I was starting to doubt weather it was really going to fullfil my aspiration,s, so set a plan for sunday afternoon testing.

The plan was to push the engine further than ever before and to hell with the consequence .so sunday afternoon left falmouth after some pre-checks down to the pandorra inn, cooling system pressure at 10psi engine 80c ,all looks good quick pint and rechecked the levels all ok. Left the pan got her up onto the plane and wound the boost upto 1 bar and nailed it and held it there for 10 minutes without any problems we ran at 53kn on gps and no problems egt 875 coolant 90 rpm 6000 ,stopped for a couple of minutes to catch our breath and nailed it some more,and more.

took her back and and everthing looks good I have had a good check over and dropped the drive oil and lower g/box cover and I,ve still even got a full set of teeth, there is still another 8psi of boost in the engine setup and 75-100c of egt in the bank to get to 7000rpm but not sure about pushing much harder intill later in the season as it might be nice to actually get some time on the water for some fun

I am really relived to find that,s its not a complete dud after all the work i have put in its never going to be a really reliable boat but not many fast boats are but its starting to tick all the right boxes for me .:

[Mollers]

If you're now in the 50's, you'll be leaving me in your wake.

[cosworth mirage]

I should be out later this week if your up fo it