P18 peformance

[stevie wonder]

Hi guys!!
I have a stonking Phantom 18 with a race tuned 2.0 litre v6 mariner 150 hp. I am currently running a Laser II 24" prop and its topping out at 72 mph, our friends have a phantom 20 with a Yamaha 225 [3.1 litre HPDI v6!] and they cant keep up above 20 mph. Does anyone have any advice on how I could improve the performance further, different prop? jack plate? I have considered a Optimax 225 but they weigh nearly 80 kgs more than the present engine and i fear this may upset the balance. How good are the 2.5efi engines? and whats the most HP I could get out of one?

[Captain Chaos]

feck it, @ 70mph, why change it?

[stevie wonder]

It feels so stable , and Im sure I could top 90mph with a big single o/b, ive seen some of the later Johnson GT 300's [4.0 litre versions] and their nice, but they weigh the same as the boat!!!

The boat used to be raced and the hull has been extencively reinforced, it used to run two of these v6 mariners and they could get well into the 100's with it. However at moment it is nice and subtle, and more than able of upsetting people round the south coast!!

So you reckon not to bother with anymore mods then?

[Matt]

Just out of interest, what's the gearbox ratio, (1.87:1 or 2:1) and how many rev's is the engine running flat out?

[stevie wonder]

1.87:1 and anything up to 6200rpm

[Matt]

How did you arrive at the 72mph figure?

[stevie wonder]

GPS

[Matt]

On the sea?

[stevie wonder]

No, the sea is normally too rough for such a light boat at that speed, the most Ive had on the sea is 64mph, i dont have trim tabs yet and it bounces around a little too much for my likening. Windermere is the place to go for speed...well, until the end of the month...goverment ba*tar*s!!!

[Hydrostream]

Do you know what has been done to the engine?

[stevie wonder]

The oil injection system has been stripped out, its been fitted with three much bigger carbs, and the inlet and outlet ports have been extncively worked on, and different gearbox [box of a 200 hp hence the 1.87:1 ratio]. The engine output is in the region of 200-220hp now.

The engine has the same transom bracket as the 275hp and 300hp mercs, which means it has the single power trim/tilt ram which gives you alot more trim out than the normal twin ram trim set up, this might explain why we can get a bit more top end???

We've used it for skiing and with a 20" laser II we were pulling up 6 mono skiers with ease and topping out @ 62 mph @ 6200 rpm. 0 - 60 times must have been around 4 seconds at the most with the 20" prop...a proper monster!!! Im thinking of getting a second hand jack plate and a chopper prop [25"-27"] and see what that does for the performance.

[Hydrostream]

Get a jackplate and a water pressure guage. Fit them and start raising the engine. You will probably need more prop as the revs start to climb. Most people dont like to spin stock pistons past 7k
but thats your choice!
If your water pressure starts to drop while you are raising the engine you can plug the top set of holes or 2 on the gearbox it will stop it drawing air.

[stevie wonder]

Will try that!!
Already have a water psi gauge and can maintain 20-25 psi at full throttle, any ideas on where i could source a manual jack plate? A hydraulic lifter would be nice but cant be arsed to spend mega bucks on one!!

Whats the spec on your weapon? it looks a bit tasty!!!

[Hydrostream]

Try posting in the buy & sell section of this site, there was a 5.5" cmc for sale a while back, might still be!

Alternatively, ebay in the USA is a good place for them, it's where I get most of my parts, shipping is not too much and even cheaper if you go by surface but it will take 6 weeks.

My boat is a 18' Hydrostream V-king, with a modified 2.4 but have now got a 2.5 200 stock engine for it also. I've had it in the 70's but didn't want to push it as the transom was cracked and the floor soft. It's now under total restoration, new floor, stringers, core, transom and knees. I hope to break a ton in it this summer if all goes to plan. :D

[Hydrostream]

and these guys are good for parts in the US.

http://rickracers.com/index.php?cPath=50&osCsid=53ea6fb103c632921e07a7a3a587189f

Alan

:)

[stevie wonder]

Cheers bud,
Best of look for the restoration and clocking the magic ton!!!

[sinkunit0]

do you have low water pick ups on your gearbox?

[stevie wonder]

No, only the stndard set up... If raising engine proves to be beneficial I might invest in that kind of set up! Whats the low down on your 200?

[Matt]

Stevie, What do you want out of the boat?
It's running pretty quick, but judging by the prop you have and engine height on the transom, I would imagine it's still very usuable, easy to cruise and ski, and probably handles OK in the chop.
Are you prepared to sacrifice these for speed?

[stevie wonder]

At present I use the 20" laser II for skiing...occasionaly, and the 24" for cruising and high speed stuff. The attitude of the boat is exceptional on flat water at speeds of 70mph + and feel that theirs still plenty more avaliable. If I get a chopper prop [25"/27"?] and jack plate for the engine i could easily transform it from one to the other quickly and without too much expence.

[roofer]

i had a 26 pitch chopper on my old 18 fitted with 200hp xr2,trying to get on the plane was a nightmare,low speed acceleration none existant,but top end was excellent.

[stevie wonder]

Acceleration with my 24" prop is still dam good and capable of lifting 2 mono skiers easily,the 20" is more for pulling arms out of sockets!!!

What sorts of speeds were you pullin with the 26" chopper???

[roofer]

when it eventually got there mid seventies, the phantom was very heavy though.

[Hydrostream]

Originally posted by roofer
i had a 26 pitch chopper on my old 18 fitted with 200hp xr2,trying to get on the plane was a nightmare,low speed acceleration none existant,but top end was excellent.

Many people on BM call the xr2 200hp, I thought it was a 150hp 2L. Ca anyone enlighten me? Thanx Alan

[Hydrostream]

It's ok I just found the answer,

http://forums.screamandfly.com/forums/showthread.php?t=45063&highlight=xr2+hp

http://forums.screamandfly.com/forums/showthread.php?t=35595&highlight=xr2+hp

[JamesM]

I think but I'm not 100% sure that the 150hp XR2 was pre 90ish and used a sleeved down 2.4 block. This was replaced by the later 200hp XR2 which used a sleeved down 2.5 block. The XR2 they talk about on S and F although also 2.0 and 150 hp is not the same race motor we have over here.

[JamesM]

See this thread to tell the difference between a 2.4 and 2.5 block.

http://www.boatmadforum.co.uk/showthread.php?s=&threadid=1946

[Hydrostream]

Thanx dude, I've seen the port difference in the 2.4/2.5 before.
So european xr2's have different porting to the US xr2's because they use the bigger motors blocks. That's interesting!

Thanks

[Hydrostream]

Is it actualy 200hp though? Thats over 30% increase in power on the 2.0l motors!

[JamesM]

Originally posted by Hydrostream

So european xr2's have different porting to the US xr2's because they use the bigger motors blocks. That's interesting!

Thanks

Forget the US XR2 that was just a name they gave to a 2.0 150hp fishing motor made some time in the 80's there are newer XR4's and XR6's fishing motors in the US too.

In Europe the XR2 is a 2.0 race motor and upto 1990ish it was 150hp and was a sleeved down 2.4 block. In 1990ish mercury stopped making 2.4's and replaced them with 2.5's, so the XR2 then became a sleeved down 2.5 block and with other updates, higher ports, bigger carbs maybe, made just under 200hp.

So its an age thing that differentiates the 150hp and the 200hp XR2's not a US or European thing. :)

As they are steel sleeve motors I would have thought it wouldnt be to difficult to port the older 150hp motor to get near 200hp.

As I said before I'm not 100% on this so if anyone knows any different please feel free to correct me!!! :)

[Jon Fuller]

I think as JBD says, about 89 the clamshell 150 XR2 was replaced with the lift off plastic coweled motor, named the XR2 Sport, based on the larger new 2.5 block, it was I think supposed to be 192hp (prop rated), and also had the CLE gearcase. In '90 it got the new mid section with open exhaust.

I think this is all correct, but Neil is the man to verify it.

[Hydrostream]

That explains a lot :cheers:

[kiwiracer]

As I understand it the last of the RACE XR2's that were made in the late 9o's were producing about 207hp.
They were quite popular in NZ as twin rigs on the 4 litre cats.

[Cyco]

Originally posted by stevie wonder
It feels so stable , and Im sure I could top 90mph with a big single o/b, ive seen some of the later Johnson GT 300's [4.0 litre versions] and their nice, but they weigh the same as the boat!!!

The boat used to be raced and the hull has been extencively reinforced, it used to run two of these v6 mariners and they could get well into the 100's with it. However at moment it is nice and subtle, and more than able of upsetting people round the south coast!!

So you reckon not to bother with anymore mods then?

Come on you lot do you really think you can fit twins on the back of an 18ft Phantom or did you miss that bit:bang: :bang:

As for the engine making 200-220hp :dizzy:
Even if it did make that power it would not be at 6400rpm to get that sort of power from a 2.0lt it needs to be spinning around 7500rpm minimum.
My finger ported XR2 that had just about every tuning mod going only made 230hp. a well tuned XR2 only makes around 205-210hp
OCRDA may pitch in on this one.
People may say what they think there motor makes but unless you have dyno run it then you'll never know.

[Cookee]

Most XR2's will make 195 - 197 after blueprinting within the RYA rules, after tuning I would have thought that given no limits and still get it on the plane 225 - 230 would be a maximum, having said that Cycos is the only one I've heard of!

XR2's arn't the most reliable engines unless very well cared for, and can be a bag of trouble when tweaked as well - there's no substitute for CC's if you want power, a nice EFI would do the trick with a lot less grief and more reliabilty - the later 280's are reliable and spending money on making them faster without losing too much reliability is possible as well.

[Cyco]

Cookee yes 197hp is about right for an RYA motor and reilistic.
My XR2 had hand ground fingerports put in and ran very high compression along with high port heights to acheive the power at high RPM.
The exhaust chest had been hogged out, it run 0.98 jetts F1 conrods, modified rod slots and a few other trick mods.
This is about the maximum without running Single ring pistons and around 190psi compression with avgas.

Then you could acheive quite alot more, but the motor won't last long.

So twins on an 18????

[Jon Fuller]

I would think forgetting all about power and speed for a moment, a twin V6 P18 would be a bit of a pig handling/ballance wise, get a 21!

[Cyco]

Your missing the point, 'this boat used to have two V6 150 on it' Quote.

You can't fit twins on the back of a P18 the engine well isn't big enough, the transom ins't strong enough, there isn't enough room to mount two motors and be able to turn them.
About the only way you could do this would be to make a massive stand off bracket that is wider the the usable area of a P18 transom.
Think of the bow lift that you would have from the motors being set back that far (2 off them) I think someone is telling porky's.

Cyco

[Jon Fuller]

MMMmmmnn, I see!

[Ian]

Originally posted by Cyco
I think someone is telling porky's.


.........or perhaps has just been mis-informed of the boats history by previous owner(s) :up:

[CB1]

The minimum centres on that type of twin engine set up and have usable steering is 19" so you can see where Cycos comming from. Also the fuel tank would have had to be enormous.

[stevie wonder]

The figure 200-220 was only ever a rough estimate, and judging by the way it leaps out of the water and blows away most 200's and 225's I kind of figured its in that area.

As stated with my earlier posts the transom and stern have been very heavily reinforced, this IS due to the fact that when I bought it their HAD been TWO mariner v6's on the back, the marks where the stand-off plate had been were still visable, the wiring inside was for 2 tachometers, 2 trim gauges, 2 remote boxes...you get the picture......

This pic shows the two engine start and cut off switches that I couldn't be arsed to take out when I re-wired the boat.

Oh the bow fuel tank takes 160 litres if I brim it.


First for everything I suppose

[Dan]

[QUOTE]Originally posted by stevie wonder
As stated with my earlier posts the transom and stern have been very heavily reinforced, this IS due to the fact that when I bought it their HAD been TWO mariner v6's on the back"

Ah ha, I`ve got it. It may have had 2 mariner V6`s on just not at the same time :drain: :drain:

[Cyco]

Got any pics of it rigged previously???

[stevie wonder]

Unfortunately not, I bought it via an agent, as the owner had moved abroad, and therefore I couldn't source any photo's of it in its twin engine state...shame really

[sinkunit0]

ive.2.5 200 my 18 and thats kinda heavy. if it had twin 150 on the back that would just be to heavy.back to your question i,m getting abot 73 running a lazer3 23p.at about 6250

[Jon Fuller]

That works out at zero slip

[Captain Chaos]

its a fkin good prop.......................Manos Industries 23P Special!

[sinkunit0]

as you know jonny the revs could be any where.the speed was on the gps .even when you knock the speed down to allow for error the slip does not increase that much 69mph 4%

[Jon Fuller]

Originally posted by sinkunit0
4%

I'll have a pair of them props! where'd ya get em? :lol:lol:

seriously tho' you say you GPS's it, where did you do this? lake, sea? ie, was there any tide/current?

[sinkunit0]

i,m right in thinking 10-15% is more realistic. it was on the river here in the speed zone honest. the flow would not be more than a knot or two .around high tide is really the only time theres plenty of water to aviod the water lice.

[Jon Fuller]

Yeah, IRO 10-12% is realistic

[sinkunit0]

so what speeds that then roughly

[Jon Fuller]

Well if your GPS speed was rock steady (ie, continuous indication, and repeatable) and the water flow there is low, you shouldn't be too far out with your speed, but if you tacho is to be believed, using 10% as your slip puts you at about 65/66mph.

But as you rightly point out, tachos are not that trustworthy and prop pitch can vary from what's stated, so the GPS is probably the most accurate of your factors, as long as the sea aint moving too quick under you, in which case you need to do a two way run, and work the average out.

I have to say, I would have thought a P18 with a decent 200 would run well into the 70's if everythings set up right, but I would have thought you'd be running a 25" prop.

JF

[Silversurfer]

Interesting stuff about the XR2 I was told mine was 200HP when I brought it I also did a scream and fly on XR2 and was gutted to see 150HP listings. Mine was built by Ocean Racing took it back there for a service and a new trim pump. The guy who built the engine said it was a strong one and DYNO'ed @ 210HP (the force is strong in this one OB1!). I have no proof of this but the engine has been really reliable and an extra 10HP for nothing makes me feel good! :D

Thanks for filling in the gaps regarding the infamous XR2!.

Regarding two V6 engines on a P18 I have to say unlikey. The sheers weight would mean that the lack of freeboard in the engine well would cause to sink unless it was powered by hot air!. I worry about the ammount of freeboard mine has!

[Matt]

Yeh, my old (1985) motah was a 150xr2, basically a slightly hopped up normal 150, completely different engine to the later xr2 'race' engines.

[JamesM]

Mat was the block on your '85 XR2 painted or just bare metal?

[Jon Fuller]

Originally posted by Matt
Yeh, my old (1985) motah was a 150xr2, basically a slightly hopped up normal 150

I think it was banded about that the original 150 XR2 was 162hp (propshaft)

[Matt]

Yep, exactly the figure I've been quoted. I wasn't sure whether it was prop or crank rated though, but yeh, 10 or 12 hp over a standard 150.
It was a painted block.
I'll check to be sure tonight, but I think the only difference to a standard 150 was the the tuner, carbs and decals. And it did say 150 XR2 all over it, so it never claimed to be one of the later 200hp race xr2's. And they all had the old clamshell cowling on.

[JamesM]

I've seen older 2.4 block XR2's that were unpainted. Mercury dont paint there race motor blocks. Also I've seen the older 80's style drop on cowl (pictured) with XR2 written on the back.

So I thought there was a race (forged pistons) XR2 around in the 80's with I thought 150hp.

Mat you must have had the fishing motor that hydrostreme was talking about earlier in this thread. There are more modern XR4's and XR6's these are fishing motors too.

[Matt]

Yeh, exactly, the 'fishing motah' :D
http://www.mattyorke.com/viewimage.html?gallery=sharpe,Image1.jpg

[JamesM]

Fishing motor - painted block, cast pistons
Race motor - unpainted block, forged pistons

You knew what I meant :D