I'm ready to make my 200hp 2.5L go faster

[Migalito]

Any ideas as where to start? It is a '99 Merc 200hp EFI 2.5L.
I want to keep it reliable for long days at the lake but would like more power.

A bad day on the lake is still better than a good day at work!

[Tony Montana]

I would start with getting your heads cut down to 34cc. That will bump your compression to around 145 which will allow you to still run pump gas (93 octane only). It is the cheapest mod and also the one you will feel the most when driving. Low water pickup on your lower unit if you have not already done so will make a big difference by allowing you to raise the motor. solid motor mounts if you have not already done it too.

Also don't discount dialing in your current setup. The correct prop, setback and motor height will do more for speed than any other mod IMHO.

[TheRickster]

As stated milling the heads would be the first thing.. If you want to go further removing the Oil Injection should be the first thing for reliability. Next would be the Cowl mod where you lift the scoop up and cut more air holes under it. I would also either get rid of the water seperator and the VST to allow more air to the Butterflies or invest in SVS.. Sending off the ECU to Rapair and getting the limiter raised to 6750 rpm would also help..

Just a few of many mods....

Rick

[camaro7081]

i am also starting my 2.5 project 96 carb motor , for me i will remove the 40 amp carging system to maybee 16 amp less of a drain , put compresion at 140 , 4 petal reeds , all the basics ...............................................................looking for a good shop in long island NY to bore and install forged pistons , and porting work .!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[The Big Al]

1st. changing to a 16amp system for the cost will not be effective. Also being a EFI it is running electric pumps and needs the 40 amp system.

Cutting the heads, yes, you already should have 4 pedals. I would change to Steve's new 3 pedals with the Carbon Fiber reeds.
Or purchase the 2 stage reed valves from Boyesen Reeds for the 4 pedal cages you have.

A Brucato PCU will help your engine. Removing all the factory modules and rev limiters off.

Removing the electric fuel pump and evaporator system, removing oil injection. Putting fuel pump in boat.
This will clean the engine up and allow more air.

Brucato SVS system I would consider a must!

Also I would look at how to modify the factory cowling that lets very very little air in. You can put lover vents on top or some XR4 Lovers in the front sides that will help. NEED COOL AIR!!!

( the XR4 Lovers look mean)

Also removing bucket, changing tuner will help.

A intake spacer from SST Marine will help.

SVS and intake spacer I would do first.

[Migalito]

Great suggestions! I will start with the heads, ECU, and getting more air into the beast.
Where can I have the heads cut?

[sinkunit0]

[QUOTE=The Big Al]1st. changing to a 16amp system for the cost will not be effective. Also being a EFI it is running electric pumps and needs the 40 amp system.

i,ve got a 200efi and have swapped to 16amp flywheel and elec and it seems to run fine

[Dutch]

to make it easy.
sell your powerhead.
buy a running powerhead/like a 225 up to a 260
send it out to make it fresh before you put it on.

[transomstand]

I'm with Dutch. Last year I was running a 150XR2, I could have spent a lot of time, money, and trouble to gain maybe 5 mph. Instead, I bought a pristine 200 bare powerhead, spent a weekend swapping parts, and picked up 8 mph.

Pete

[Migalito]

I agree, if you are looking to really hotrod a boat, or car, nothing beats a bigger motor. But I just want to make my 200 run more like it is supposed to, unrestricted. Kinda like a super tune-up, make it breathe better.

[TheRickster]

Playing the devils advocate here... Say you spend 3000-4000 $$$ on a 225 ProMax drop on... Yes you do get a specially curved ECU and an unpainted PH... But you also have cast pistons still, in most cases plastic caged rod bearings, and have the same injection system you have now.... I think for less than the cost of buying a Drop on ,and still having to go into it possibly, you can go through your powerhead and upgrade to forged top-pinned pistons and metal caged bearings.. You can send your ECU to Rapair and get it flashed to whatever they think you need for your modifications and then you can pay someone like Jay S. or John (US-1) to port you up to 240hp spec and then you have the pride of knowing what you have in the motor parts wise plus you have learned a lot aout engines which buying a drop on would not have taught you....

Rick

[vector mike]

Playing the devils advocate here... Say you spend 3000-4000 $$$ on a 225 ProMax drop on... Yes you do get a specially curved ECU and an unpainted PH... But you also have cast pistons still, in most cases plastic caged rod bearings, and have the same injection system you have now.... I think for less than the cost of buying a Drop on ,and still having to go into it possibly, you can go through your powerhead and upgrade to forged top-pinned pistons and metal caged bearings.. You can send your ECU to Rapair and get it flashed to whatever they think you need for your modifications and then you can pay someone like Jay S. or John (US-1) to port you up to 240hp spec and then you have the pride of knowing what you have in the motor parts wise plus you have learned a lot aout engines which buying a drop on would not have taught you....

Rick

My thoughts exactly.

[vector mike]

Just keep your motor untill you build another one from pieces and parts and then sell the 200 to get back most or all of your money. That way you know what you have.

[Slickone]

If you are not already using ALISYN ProGear Type 1 in your lower unit, try it. You will see an RPM gain of 200-300 RPM depending on what you are currently running. I assure you it will be the least expensive power gain you will get.

Please see the product evaluation posted on S&F. Also, while you're at it please try our ProPower 2 cycle oil.

To see what others have to say about our products and service, please type in ALISYN in the forums search bar.

All S&F members receive free shipping from Aerospace Lubricants, Inc. If you have any questions, please contact me.

[email protected]
www.aerospacelubricants.com

Best regards,
Jerry

[Dutch]

260 drop on + $4500
rebuild, labor/parts + 2500
sell old power head - 3000
money out + 4000


his motor-
rebuild powerhead
w/labor/parts + $2500
port block if wanted + 500
ecu recurve + 400
money out + 3400

so for a difference of $600 he could have a horn efi nicasil motor
with all the factory high perf stull. if it was my money i know what
i would do. but then i also run a drag motor on a lake boat