How to add power

[rpod86]

I have 1999 2.5 efi mariner pro mag 150 I have been looking at new reeds velocity stacks and exhaust tuners, does any of these work? I really don't want to do anything like punch out the block or stuff like that

[FORBESAUTO]

Without internal changes won’t usually see a big gain. May idle soother and cleaner with reeds. Tuner will only move power curve around, again to get full benefit internal changes needs to be made. Velocity stacks are for carb motors. When doing reeds, you can add stuffers and an intake spacer and you will get a noticeable improvement on acceleration. Won’t see much change in top speed, but get there quicker and much more fun to drive.

[FMP]

Was the intake, front , throttle specific to the 150?

[FORBESAUTO]

Not really specific to 150, especially performance wise, all the 4/5 petal fronts and intakes for the 2.5 are the same.

[rpod86]

thanks everyone a mechanic told me I can change injectors and ecm and make it a 225 is this true?

[FORBESAUTO]

Might can gain a little hp with ecm, but not 225. Total different porting/exhaust/intake setup on a 225. Without opening motor; reeds, spacer, stuffers, indexing flywheel to 25 btdc on all cylinders and setting timing to 25 on highest running cylinder, and shaving heads will give ya the best bang for ya buck. Even with these mods you’ll only see a few mph increase, but it’ll be considerably quicker. If ya lookin for speed, time to get serious and spend money or bigger hp powerhead. If ya gotta pay for machining, porting and such, its cheaper to swap poweheads. If ya can do a lot on your own, much more fun to build your own stuff and get the satisfaction of I did that.

[Merc 2.5]

With those mods u mite b able step up a size on ur prop and get sum more top end out of it. I know mine did but was a short light boat ,and was easier to feel power change in everything i done ,,a bigger boat /heavier won't b as noticeable I wouldn't think my .02

[FORBESAUTO]

Anytime you pick up power or responsiveness, it’s a gooood thing!:thumbsup: You pick up 2 mph, that’s 2 you didn’t have before :D

[Merc 2.5]

You are liable to get more just by your setup. In other words make sure u r setup is at its full potential b4 starting mods. Do u have a jackplate? Hydro or manual?

[nitro_rat]

Some info and specs on the boat will be useful to get an idea of how it’s running now. Boat model, length, propshaft height, jackplate, prop, gps top speed and rpm at that speed...

[FORBESAUTO]

You are liable to get more just by your setup. In other words make sure u r setup is at its full potential b4 starting mods. Do u have a jackplate? Hydro or manual?

:iagree:100 %. Top end spend is effected more by setup than anything else. Don’t get me wrong, a few extra ponies definitely helps and can give ya a few more options on setup, but in the end more is to be gained by setup than engine mods. You won’t regret any of the mods you’ve mentioned, mainly because the added midrange power makes the boat so much more fun to drive and the increased responsiveness of the motor greatly improves how the boat handles and comes out of turns.

[tomoad]

Have ur heads cut to 34cc. And run premium fuel. Bout all ur going to do without going into the motor

[Dave S]

Exhust ports ....tuna..... jets.

[rpod86]

sorry been busy.. this motor is on a 180 prov blazer 23 pitch tempest 58.7 gps at 6500 manual jackplate and a hydro tail thing but the boat over revs when I trim it up to the point it feels right and sitting high in the water

[rpod86]

what does tuna mean?

[rpod86]

will measure prop shaft hight tonight

[rpod86]

Was the intake, front , throttle specific to the 150?
yes the mech told me so anyways

[nitro_rat]

what does tuna mean?

It's coon azz for "tuner"

[nitro_rat]

Best bang for your buck for "hop ups" will be a set of reeds and reed stuffers from Chris Carson, also you can have Chris or James Perry (closer to you in TN) cut your heads. That will give you a little more compression and should improve your bottom end and midrange. Probably won't effect your top speed much. I don't know what tuner your motor has but unless it's a really crappy one you won't notice a difference with a change.

If you do go so far as to change the tuner you should really think about swapping to solid motor mounts since you'll be down that far anyway. Also you could ditch the liner in the can and drill the bottom of the leg for exhaust relief like the hi-po motors.

Setup will be where you get most of your speed from though!!!

[Merc 2.5]

Lol tuner more than likely. That prop is gud all round prop what's is the prop shaft to pad? Low water pick up?

[Merc 2.5]

My phone is being very slow today what nitro said lol

[nitro_rat]

Also, do you have a good working water pressure gauge and tach?

[tlwjkw]

thanks everyone a mechanic told me I can change injectors and ecm and make it a 225 is this true?

"
Was the intake, front , throttle specific to the 150?"


yes the mech told me so anyways

ya need ta find 'nother mechanic!

[rpod86]

"
Was the intake, front , throttle specific to the 150?"



ya need ta find 'nother mechanic!
I wish I knew 1 around here that done boats most say they wont put mods on due to the reliability issues, I am not looking to break any records or anything,just make it better, faster this guy is only 1 willing to do mods I have found so far.

[nitro_rat]

You’re far better off working on it yourself, especially if you want to start hot rodding.

[tlwjkw]

have an oem manual?.. if not send me an email addy and I'll send ya one in pdf.. will help ya a lot with what ya got and identifyin' parts.....

[nitro_rat]

have an oem manual?.. if not send me an email addy and I'll send ya one in pdf.. will help ya a lot with what ya got and identifyin' parts.....

Do you have a pdf of an 80’s manual? I have the 76-79 and all the 92-up stuff, but not one for the XR-2 and XR-4 era!

[tlwjkw]

sorry but nope.. those were before tha computer took over and either wore 'em out or went with tha sale of all my junk few years ago.... haven't been able ta find in pdf... checked ebay lately?... show up there ever so often.