Xr2 150, 1987

[croSSed]

I just acquired one of these. How high can I rev this motor safely? The factory says 5500-6000. Can I run 87 oct gas on this thing without fear of detonation? I read something recently about timing adjustments for this motor or one similar. Is there anything I need to know on that subject? Thank you!

TG

[olmo40]

Depending on the condition of the motor ?? These 2L blocks were one of Mercurys best in 135-150hp guise,they will take an absolute flogging .In standard form id be happy to run mine at low 7000rpm ,If you modify it and balance it ,the motor will run harder again ,your next decision will be how long a life do you want out of the motor.?? Remembering the motor is ideally suited to lighter smaller boats in a performance application.87 octan is fine for standard compression.

[Juggernaut]

as with any morot, the higher you rev it, the lower the life expectancy. from what ive heard, the 2.0L motors are like the chevy 305. nearly impossible to kill with rpms. but i wouldnt go too high. i run my XR2 at 6900 rpm. i wouldnt sugguest going over 7200 rpm. but, when you run over 6000 rpm, you MUST run 32:1 oil. the factory rated the XR2 at 6000 rpm because that is all the factory injection pump can handle. if you are going to run above 6k, you have to disconnect your injection pump and premix your fuel.

[croSSed]

as with any morot, the higher you rev it, the lower the life expectancy. from what ive heard, the 2.0L motors are like the chevy 305. nearly impossible to kill with rpms. but i wouldnt go too high. i run my XR2 at 6900 rpm. i wouldnt sugguest going over 7200 rpm. but, when you run over 6000 rpm, you MUST run 32:1 oil. the factory rated the XR2 at 6000 rpm because that is all the factory injection pump can handle. if you are going to run above 6k, you have to disconnect your injection pump and premix your fuel.

Isn't there also some point at which your HP drops off? What rpm does this motor make its peak HP?

TG

[Juggernaut]

from what ive noticed with my motor, power comes in between 5800-6800rpm. i can feel the power dropping off a little when you get towards 7000 rpm. but where the power feels like it is can change from prop to prop, so finding a good prop and rpm is really trial and error. my original prop was a 3 blade 14.5" 26p cleaver. i ran roughly 6200 rpm. i downsized to a 14.5" 24p cleaver, and picked up 700 rpm, and maybe 5 mph. borrow props. its the best (and cheapest) way to test your boat.

[ZonkaRacing]

Great thread,
I also just got an XR2 this spring, and was wondering the same thing bout peak hp and fuel mixture.
What are the compression #'s of your XR2 Juggernaut?
Mine are between 110-115 cold. I've also got a CLE w/ 1.87 gears but can only turn a 14x30p cleaver 5350rpm (pshaft 4" below). Is that kinda low?

I also got the fuel injector removed, and mix 50:1 but if i turn 6000-6200 i think i'll start to mix 40:1, but when idleing/cruising other then the extra smoke wouldnt that cause the motor to get hot or cause damage?

[Juggernaut]

Great thread,
I also just got an XR2 this spring, and was wondering the same thing bout peak hp and fuel mixture.
What are the compression #'s of your XR2 Juggernaut?
Mine are between 110-115 cold. I've also got a CLE w/ 1.87 gears but can only turn a 14x30p cleaver 5350rpm (pshaft 4" below). Is that kinda low?

I also got the fuel injector removed, and mix 50:1 but if i turn 6000-6200 i think i'll start to mix 40:1, but when idleing/cruising other then the extra smoke wouldnt that cause the motor to get hot or cause damage?
to be completely honest, i have not done a compression test on this motor yet. but to get your rpm's up, the 1st thing you have to do is jack that motor up. i run 2" below the pad, but thats because i cannot get any more height from my manual jack plate. try going up 1/2-1 inch at a time, and keep an eye on your water pressure. then what you have to do is drop the pitch on that prop. get the rpm's up. 5300 pm is bogging down your motor and causing it to work harder. i would shoot for 6000-7000 rpm, but just remember the more rpm you run, (generally)the less life your motor will have. a 50:1 ratio should be fine for what you're running, but if you run more than 6000 rpm, richen up your oil mix to 32:1. it will keep the engine well lubricated at high rpms. it may be a little heavy for running say 6200 rpm, but i would still do it because extra oil doesnt hurt anything. its more of a safety precaution. when running one of these motors at 32:1 at idle, it will smoke. it doesnt hurt anything to be over-lubricated, and ive never had overheating problems. if you have any more questions please PM me

[creeljd]

to be completely honest, i have not done a compression test on this motor yet. but to get your rpm's up, the 1st thing you have to do is jack that motor up. i run 2" below the pad, but thats because i cannot get any more height from my manual jack plate. try going up 1/2-1 inch at a time, and keep an eye on your water pressure. then what you have to do is drop the pitch on that prop. get the rpm's up. 5300 pm is bogging down your motor and causing it to work harder. i would shoot for 6000-7000 rpm, but just remember the more rpm you run, (generally)the less life your motor will have. a 50:1 ratio should be fine for what you're running, but if you run more than 6000 rpm, richen up your oil mix to 32:1. it will keep the engine well lubricated at high rpms. it may be a little heavy for running say 6200 rpm, but i would still do it because extra oil doesnt hurt anything. its more of a safety precaution. when running one of these motors at 32:1 at idle, it will smoke. it doesnt hurt anything to be over-lubricated, and ive never had overheating problems. if you have any more questions please PM me
I have a 1973 MX15 project boat that I'm putting a 2007 Optimax 115 on it. What kind of performance and handling issues do you see with the XR2?

[T-REX]

I've also got a CLE w/ 1.87 gears but can only turn a 14x30p cleaver 5350rpm (pshaft 4" below). Is that kinda low?


U have one strong 2liter my fren!!!......U lucky it will git out tha water!!!....U must have one light bote!!!!......

I have a stock 150 2litr on a 500# contender tunnel, 2:1 geers and a 24" Lightn'in et copy...7200rpm......That iz about max for a fish'in 2liter...I have seen 7400 outta a XR2, but only one!!...I juss put tha same mota on a 18' sprint bass bote, and the same prop and geer, 6700 iz max...

U will kill yo lil mota faster wit them low rpm(lugg'in) than ya will spinn'in it 6500-7000....Keep enuff fuel in it, keep it cool, and ya have no electrikle issues, that lil mota will last for yeers, and yeers turn'in 7000rpm+....

Keep tha rpm in the 6000-7000 range, and a 2liter will outlast any other ov tha larger CI motas...JMO

[ZonkaRacing]

im deffinetely gonna set it up next year to spin in the 6k range
boat weights about 750 from wat brochures say + driver + stereo + fuel, not sure if thatd still b considered light, but thnx for chimin in t-rex. great info :thumbsup: