P18 peformance

[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/forum...ghlight=xr2+hp

http://forums.screamandfly.com/forum...ghlight=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/showth...&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

[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

As for the engine making 200-220hp
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)