How can I get 200 hp from my 150 EFI Merc?

[stealthperf]

It can be done!! I did it to mine. I did do all the work myself, however, I have a full machine shop and porting equipment. I build race engines for snowmobiles for a living and decieded to do my motor myself. I started with a 2001 150EFI on a Procraft Pro185(not a fast hull either). The way it came from the dealer it would run 60.3 with the best prop being a 24" Trophy. With a jackplate and hood mod the best was 63.3. Pulled the power head and ported it,changed the tuner, modified the reed cages and installed Boysen reeds, best speed last year of 74.6 w/24" TXP 3 blade. This spring I installed a new 12" Rapid Jack, intake spacer, and SVS. I took it out the first time last Saturday and was cruising at half throttle(just before the SVS started to open) and looked at the GPS @ 61MPH. I thought it was funny that the boat only went this fast before at wide open!! I found a bay with no traffic and was cruising at 55 MPH and hit it wide open. In about 200 yards the the GPS was going past 72 and climbing fast! I haven't had a chance to see how fast it tops out at because I need to learn how to drive it better or work on my set up or both. The wheels definitly start coming off when it's pulling that hard at that speed. In short, it can be done! Hope this helps, Dave.

[Mesabooger]

stealth, which tuner did you change to? do you have any pics? sounds like a nice set-up. Did you change the bore, stroke or anything when you had the engine apart or did you get all that gain from just porting the heads, modifying the reed cages and changing to boyesen reeds? You make this sounds do-able again. If I can get to 70 mph with some porting, a jack plate, prop change and boyesen reeds that would be great. TIA

[trashy]

I'll be honest with you Mesabooger, getting to 70 mph with that hull and that motor is going to be quite a challenge. Rangers are very heavy boats and are built more for comfort and fishing than they are for speed.

The first step in the process would be to get a jackplate. Measure the height between the center of the lower unit and the pad of the boat for reference. Once you put a plate on, I would probably go a little bit higher with the motor and see where your rpms are. You should be running at 5800 when wide open. If you can't get those rpms by adjusting motor height, the next step is to try a different prop.

I have found that the Tempest Plus is a little faster and seems to have a little more lift than the Trophy, but we're talking about a Gambler not a Ranger. If you can, try both and see which one runs better. Once you get to that stage, send the prop to get worked by a good prop guy.

I would think that taking those steps first will easily gain you some speed. Once you get to that point, then think about further mods to the engine. Without getting the most out of your engine while stock, you're just wasting your time and money on engine work.

That's just my opinion. I am by no means an expert, but those are the steps that I took to get to where I'm at now. Mine isn't the fastest rig on the water by any means, but it's one of the faster ones with the setup I have.

[trashy]

The first step in the process would be to get a jackplate. Measure the height between the center of the lower unit and the pad of the boat for reference. Once you put a plate on, I would probably go a little bit higher with the motor and see where your rpms are. You should be running at 5800 when wide open. If you can't get those rpms by adjusting motor height, the next step is to try a different prop.

By the way, I did fail to mention one very important thing that you need to watch for. If you don't have one, get a water pressure gauge and keep an eye on it. You don't want to run less than 12 psi at WOT.

[pyro]

DON'T BELIEVE EVERYTHING YOU READ ON HERE. Everybody has an opinion, and some of them are coming from 16 year old kids whose father actually owns the damned boat. People's high post count also doesn't imply that they know their stuff. You're armed with the info you need if you read the replies here carefully. If you start writing off expert opinions (I'm no expert) and believing everything that other newbies tell you, you'll spend money and get nowhere.

Correct water pressure depends on a number of factors. It's not always the same number on every motor. Some motors run closer to 18-20, in which case 12 could mean death. Also, a healthy water pressure number might not always reflect aeration, bubbles in the cooling system, which can still cause an overheat. Boiling water may appear to show as running water pressure! Watch your temps.

Most who use a jackplate, also have a nosecone with low-water pickup intakes to allow the higher settings. You can also block off a couple of the highest sets of stock side intakes for moderate engine height.

"Porting" isn't a head issue, it's a block modification. It usually involves making the exhaust ports taller and/or wider-- alongside other mods such as exhaust chest cutting, rod mods, etc, you can raise the powerband into a higher RPM range at the expense of some low-end grunt. Not always a worthwhile trade-off on a heavy boat!

The easiest, most effective way to gain more power is to mill the heads for 140-145 psi cranking compression (up from the factory 120-125 psi.) You can do this without modifying anything else and get some instant gratification. Increasing compression will slightly increase wear on your internal parts.

A tuner change by itself won't likely amount to any big difference.

to recap:

1. Get a jackplate. Block off top 1 or 2 sets of water intakes. Jack up your Tempest a bit, as long as you still get good water pressure, and as long as RPM doesn't go up with no speed increase. You want the most speed and the least "slip." find the sweet spot. Cost: under $300, as previously stated. More like $400-750 for a used hydraulic plate.

2. Not fast enough? Get ahold of a set of tighter heads and gaskets and give it some more squeeze. Cost: under $150 if you buy a used set of heads.

3. Still not enough? Sell your motor or powerhead before it's been overly messed with, ruined and worthless from risky mods, then use the money from selling it, to BUY A 200.

4. THEN, if the 200 isn't enough, you can start doing mods on it.

[Fish]

DON'T BELIEVE EVERYTHING YOU READ ON HERE. Everybody has an opinion...

to recap:

1. Get a jackplate. Block off top 1 or 2 sets of water intakes. Jack up your Tempest a bit, as long as you still get good water pressure, and as long as RPM doesn't go up with no speed increase. You want the most speed and the least "slip." find the sweet spot. Cost: under $300, as previously stated. More like $400-750 for a used hydraulic plate.

2. Not fast enough? Get ahold of a set of tighter heads and gaskets and give it some more squeeze. Cost: under $150 if you buy a used set of heads.

3. Still not enough? Sell your motor or powerhead before it's been overly messed with, ruined and worthless from risky mods, then use the money from selling it, to BUY A 200.

4. THEN, if the 200 isn't enough, you can start doing mods on it.

That's good advice there.

[tlwjkw]

Sell tha boat. Keep tha motor. Get ya an Ally, Bullet or Laser............

This thang is startin' ta smell funny or is it just me. (maybe bovine caca?)

T

[stealthperf]

I got a Bob's tuner. Stock bore & stroke. Also I had shawn at Rapair reflash my ecu to 200 promax spec. He also reflashed it again when I installed the SVS. Dave

[Mesabooger]

After listening to all the warnings and such, maybe I'll just get a jack plate, some boyesen reeds and get the prop reworked. Thanks for all the advice....good or bad.

[The Big Al]

Pyro has givin some great info:

Here is a good place to find a water pressure gauge deal! http://www.reynoldsracingmarine.com/images/wpgauge.jpg


Kit to help with 8 hole lower unit run a little higher without the nose job!

http://www.reynoldsracingmarine.com/probsolv.htm

Replaces the 8-hole insert on Mercury 2.0L, 2.4L, 2.5L, and 3.0L outboards with 4 3/4" gear cases except the 225/250 (3.0L 1994-1996)
$ 39.95 each kit *

[trashy]

Correct water pressure depends on a number of factors. It's not always the same number on every motor. Some motors run closer to 18-20, in which case 12 could mean death. Also, a healthy water pressure number might not always reflect aeration, bubbles in the cooling system, which can still cause an overheat. Boiling water may appear to show as running water pressure! Watch your temps.

I guess I can agree with that. Mine runs well above 12 psi (which is the identical motor that we're discussing here). The "rule of thumb" that I have always been told by a few different mechanics has been 12 psi minimum. Also, according to my shop manual, the specs are 12 psi minimum @ 5500 rpms.

That being said, I don't know how Rangers like to run. He may not need to jack the motor up high enough to where losing water pressure would be an issue.

[Wizard]

You can do everything to that motor possible to make it 160 hp and it will not get your Ranger much over 70. There's HP and there's Torque. A 2.4L block can be made to make HP, even up to 250HP but it can't make the kind of torque necessary to turn a large diameter high pitch prop to the rpms needed to lift and run that Ranger. If you go the whole heads, intake, ECU, Tuner and porting route you will see greatly improved acceleration but your top speed will be a dissapointment based on the money you spent. If you had a lightweight hull I would say go for it but I think your wasting money.

For the $3500-$4000 you would spend hopping up that motor your better off selling your 150 and buying a used 200 or 225. There are plenty of 225EFI's floating around for 8 grand. You will spend about the same amount of money and go way faster. By doing all these mods I think you will ultimately be dissapointed. Not only that but your engine will be much less reliable. Why risk it for so little gain.

If you like your hull and really want to go 70 then sell your motor and buy a used 225. Then you will easily run 70 loaded for fish.

Having said that I also agree with Pyro. There's always a little something to be gained by set-up. 10" is alot to be handing off that thin Ranger Transom but it can be done if you don't run in really rough water. The jackplate and some propwork will get you over 60 I'm sure.

[Mesabooger]

My problem with changing to anything over a 200 is that it will exceed the rating sticker. In these tourneys I fish, that will DQ you quick and if you win they check everything. Trust me, I saw that first-hand. One minute a guy has a new Chevy truck and a new Raner 519 and the next he's DQ'd simply becuase the boat he was using didnt have a maximum specs sticker. So my engine has to at least appear to be a 150 or 200. Going to all the trouble of selling my motor and then buying another is a hassle I can do without. Maybe I'll just sell the whole damn thing and buy another boat.

[pyro]

It's not much of a hassle at all, it's less than an hour of easy work.

[Mesabooger]

What is a fair price for a set of stock 2.5l heads?