Optimax Pro xs and regular xs, how many years in production?

[Madhatter447]

Hi there.

Is there someone in here on scream and fly that knows how many generations of Mercury
Optimax Pro XS and regular xs are there? And when did the production of these started?

Seems hard to find info about that.

[hsbob]

the 200xs opti started in 2001. as a starting point.

[Madhatter447]

the 200xs opti started in 2001. as a starting point.

Ok and the rest?

[Tango]

Madhatter...

The Optis actually have been around since 1997. From 1997 til 1999 you could identify them by having two TPS sensors for redundancy. In 2000, Mercury switched to the TPS & MAP. If one failed, the other would take over using known values... if they both failed, you were stuck at idle speeds to get home.

Depending upon which model year and horsepower you are looking at, the 2.5L versions of Optis were pretty sedate except for the 175hp models which had tighter heads for more compression. In 2001, both 2.5 and 3.0L had new head seals for better sealing.

To address your question on the Pro XS models... they came with mostly offshore parts. The powerhead differences were minute' but here are all the bigger production changes.

In 2003 the 250XS Optis were bare alodine, and hand made by Mercury Racing. Quite quickly BASS users were getting slammed by the competition for having modified engines due to a distinct power advantage. These motors will show 140-160 psi cranking per cylinder compared to a black 2004 block which will show 120-135 psi per cylinder cranking. The earlier heads aside from being bare aluminum have the 858495-4 and 850406-5 part numbers. They are easier to identify by the coolant port sending unit which moved from inboard to outboard side of each head for better fluid contact and less restriction of flow.

The air inject systems have changed nearly each year from 2000 through 2006 to fix issues in the systems which would lead to failures of the pumps, including pump redesigns.

Due to continued pump and injector variances, Mercury released an easy and fast way to make resistance (ohmsvalue) checks on direct injectors and a quick harness to hold them open with a 9-volt or 12 volt battery by using, service harness 84-858781A2.


In 2003, the VST was redesigned to become an INTEGRATED VST or IVST and it no Longer had the filter attachment. This was significant for later upgrades and to reach a cleaner burn with the total capable fuel pressure bump from 109 PSI to 120 PSI. There are also differences in the tracker valves which make sure the fuel pressure stays ahead of the air pressure. This is why when an air pump fails... the engines lean out immediately as the fuel pressure will drop significantly. The Tracker is specifically designed to balance out pressure spikes but still maintain a 10 psi differential.

Oil injection pumps and the tube routing changed each year from 1998/99 through 2003.

The wiring harnesses and coil packs changed in 2006 to the 14pin camlok design. Earlier models will still have the Termination Resistor at the ECU that can be run with the 10 pin harness with a blue data cord coupled with a terminal junction block. Rigging is specific to the application you are building and what accessories you want to run.

This is pretty much what I have learned in being the differences on the Optis in the 250hp range. The 300XS models have all the newer updates here plus the stroker crank and different springs in the Tracker and FPR. If you port or do some work with a 250 and swap out these parts, you will need a DDT to trim the fuel within limits. Another trick is to shim the FPR or install a standalone FPR after the fuel rail going back to the IVST. Doing this can cause the VST high pressure pump to deliver up the the max of 120 psi of fuel pressure, noting the target fuel pressure is 90 psi.

When I get my Eliminator up and running... I plan to experiment with using a NOS regulator to control an additional FPR to bump fuel pressure with a Kenne-Bell Boost-A-Pump and see if that will give the desired fuel to use the Air pump injectors to distribute Nitrous through the Air injectors at the head.


I hope this helps.... it took a bit to share.

[Whaaaaat]

I've been having the same thoughts, I think. Are you saying your gonna try to use nitrous instead of the compressor?

[Tango]

I've been having the same thoughts, I think. Are you saying your gonna try to use nitrous instead of the compressor?

I would not use Nitrous instead of the compressor. What I intend to do is install a Fuelab vacuum pressured, electronic return fuel pressure regulator (FPR) between the Opti Fuel rail and the VST. I will also install an NOS Nitrous Regulator, the same kind used with dry nitrous systems. The Nitrous Inlet will be installed AFTER the Compressor and before the Fuel/Air injection rails using a TEE and pressure check valve. At the Solenoid for the Nitrous, when it activated it will send metered nitrous to the air injection/fuel rails through the existing air injection system. The NOS regulator sends 50psi of nitrous pressure to the Fuelab FPR essentially cutting off the fuel flow back to the VST which causes the VST pressure to spike to 125 psi. Since the tracker is designed to keep Air Pressure within 10 psi of fuel pressure, it will allow the spike in air pressure with the nitrous before dumping the excess to the overflow valve, which will be redirected from the exhaust plate to the intake under the throttle body.

What I have is a very high tech Direct Port to the combustion chamber Nitrous system with exacting fuel regulation. The Air temp sensor mounted in the intake will see the temp drop due to the overflow valve dumping pressure and it will increase fuel injector pulse as well as the increase of fuel pressure to deliver the necessary fuel. At the same time it will retard the timing and look at coil dwell time to fire off the combustion as it will not see a rise in MAP or change there. Doing it this way gives me tunable ways to tailor fuel pressure, nitrous flow and injector timing.

I am not looking to add 100+hp, maybe 50hp or 75hp to each motor. What I am wanting to do is run from a 40-roll and have my Skater at 7100 RPM in 3/4 mile with a pair of 36" pitch five blade wheels.

Any questions?

[Whaaaaat]

I would like to experiment with one to get it to run without the compressor. The volume of air needed can't be much. Should be able to run from the vapor side of a nitrous tank.

[XstreamVking]

Seems there was a guy working on an onboard elec compressor to eliminate the belt driven compressor a while back on here. The air consumption #'s he gave were fairly small. I would think that some better pistons would be needed to apply nitrous.

[Whaaaaat]

I'm thinking the amount of nitrous needed would be so minimal as not to have much effect. As would only be using the vapor side. Really any compressed gas would work. Only need a little blast to atomize the fuel. Removing the need for the compressor and it's parasitic drag and rpm limits. Nitrous having the benefit of liquifying at ambient temperature maximizing space as far as storage.

[XstreamVking]

Sticking with compressed air would be the most sensical. Throwing N20 at it would be another factor for failure. Having a compressor replaced is nearly a Grand and if you could come up with a alternative that worked reliably it would be something to consider. I believe a small elec compressor is the ticket. You only need 120 psi so why go to a hi pressure tank the has to be refilled on shore? Over complicated needlessly.

[Whaaaaat]

My original thought was not to delete the compressor for the average guy, but for racing applications. For more of an everyday use I think a easier to access gas could be found. Propane was my first thought, but I think it might have more negative side effects than nitrous.

[Madhatter447]

Madhatter...

The Optis actually have been around since 1997. From 1997 til 1999 you could identify them by having two TPS sensors for redundancy. In 2000, Mercury switched to the TPS & MAP. If one failed, the other would take over using known values... if they both failed, you were stuck at idle speeds to get home.

Depending upon which model year and horsepower you are looking at, the 2.5L versions of Optis were pretty sedate except for the 175hp models which had tighter heads for more compression. In 2001, both 2.5 and 3.0L had new head seals for better sealing.

To address your question on the Pro XS models... they came with mostly offshore parts. The powerhead differences were minute' but here are all the bigger production changes.

In 2003 the 250XS Optis were bare alodine, and hand made by Mercury Racing. Quite quickly BASS users were getting slammed by the competition for having modified engines due to a distinct power advantage. These motors will show 140-160 psi cranking per cylinder compared to a black 2004 block which will show 120-135 psi per cylinder cranking. The earlier heads aside from being bare aluminum have the 858495-4 and 850406-5 part numbers. They are easier to identify by the coolant port sending unit which moved from inboard to outboard side of each head for better fluid contact and less restriction of flow.

The air inject systems have changed nearly each year from 2000 through 2006 to fix issues in the systems which would lead to failures of the pumps, including pump redesigns.

Due to continued pump and injector variances, Mercury released an easy and fast way to make resistance (ohmsvalue) checks on direct injectors and a quick harness to hold them open with a 9-volt or 12 volt battery by using, service harness 84-858781A2.


In 2003, the VST was redesigned to become an INTEGRATED VST or IVST and it no Longer had the filter attachment. This was significant for later upgrades and to reach a cleaner burn with the total capable fuel pressure bump from 109 PSI to 120 PSI. There are also differences in the tracker valves which make sure the fuel pressure stays ahead of the air pressure. This is why when an air pump fails... the engines lean out immediately as the fuel pressure will drop significantly. The Tracker is specifically designed to balance out pressure spikes but still maintain a 10 psi differential.

Oil injection pumps and the tube routing changed each year from 1998/99 through 2003.

The wiring harnesses and coil packs changed in 2006 to the 14pin camlok design. Earlier models will still have the Termination Resistor at the ECU that can be run with the 10 pin harness with a blue data cord coupled with a terminal junction block. Rigging is specific to the application you are building and what accessories you want to run.

This is pretty much what I have learned in being the differences on the Optis in the 250hp range. The 300XS models have all the newer updates here plus the stroker crank and different springs in the Tracker and FPR. If you port or do some work with a 250 and swap out these parts, you will need a DDT to trim the fuel within limits. Another trick is to shim the FPR or install a standalone FPR after the fuel rail going back to the IVST. Doing this can cause the VST high pressure pump to deliver up the the max of 120 psi of fuel pressure, noting the target fuel pressure is 90 psi.

When I get my Eliminator up and running... I plan to experiment with using a NOS regulator to control an additional FPR to bump fuel pressure with a Kenne-Bell Boost-A-Pump and see if that will give the desired fuel to use the Air pump injectors to distribute Nitrous through the Air injectors at the head.


I hope this helps.... it took a bit to share.

Thank you very much Tango, I really appreciate this info and for you to taking the time to write down all this. As I understand it was only 2 generations with theoptimax Pro XS then?? First generation 2006 and the second 2012/13 - 2018 or am I wrong here ?? The usual XS 115-300 Mercury Custom made 2000 - 2005 ?? was probably a sequel to xr2 and black max but that it was then called Optimax XS or ??


A pro xs 250 would sit just fine on my Swedish-built Stiletto 22 don´t you Think??

PS: You don't know anyone in the US who has a 250 Pro xs first generationwith low hours, with L shaft 20 and who might want to trade to my V8 Black Johnson 300 4L 1996 and that I can put some dollars in between if needed ?? The V8 is in Sweden though.

Maybe this last quote is in the wrong Place here att scream?? and should be on the sales menu instead??

Sorry for bad English!!(you know Sweds)

[Tango]

Sorry for bad English!!(you know Sweds)

One of my best friends in High school was from Uppsala and couldn't speak a word of English til he got here!

I do not know of anyone with a motor to swap.

[Madhatter447]

One of my best friends in High school was from Uppsala and couldn't speak a word of English til he got here!

I do not know of anyone with a motor to swap.

1. Haha maybe my english isn't that bad after all.

2. Took a chance, thanks anayway.