evinrude powerhead swap

[bruce180vf]

I have a blown up 1990 xp150 looper that needs bored and a new crank. What are my options for swapping to a 175 or 200 that will fit on my mid section or should I rebuild the motor. I could get a reman powerhead but I would like to know what I have on the inside.This is on an 18ft Charger bass boat. I would like to see mid 60's. The previous motor went 58 gps. I know there is no substitute for cubic inches. The boat is rated for a 150 so I would have to keep the stock cover.

[Lockjaw]

I would find a 235 and put that on there, and keep your cover. There is one for sale in the motors section. I don't think you can do much with the 150, because it has a flat back exhaust.

I have a GT175, and I don't see appreciably better speeds then you are seeing. I have an 18 foot BB and while working out issue's, I have seen as high as 58.5 on a speedo, so don't think a switch to just a stock 175 will help much. In my opinion.

The upside to a 175 is it is really a 235, although it doesn't turn as many rpms. I have the really good heads to go on mine, and reeds, and a few other things, and hope that helps. I will however have to port mine to get it to perform like I want, and I have a 175 limit as well. It has the turtle back exhaust, so its good there.

Seriously, do the 235, find the good heads, Neveredge has a set, and they are not cheap, and run super unleaded.

My friend along time ago had a Glasstream with a 235 on it, and a 150 cover, and let me tell you it would stroke. He didn't fish out of it, so it was pretty light compared to a fishing boat, but I bet it would have run into the 80's.

Racer can port an engine for you to, shoot him an email. He is who will be porting mine when I break down.

[half fast]

You said looper in the post,are you sure it's a looper and not a cross flow ? hf...

[dynobo]

Bruce, if you have a 1990 150 you most definitely have a crossflow not looper. Any of the 1976-1991 v-6 crossflow powerheads will drop on with no problem. The 235 and some 175's had different exhaust plates but these are also bolt on deals. The GT 150 is a pretty hopped up motor compared to standard 150's so If you want to add 7+ MPH to your rig you may be looking to score a 200 or 235 powerhead. You may be better off selling the 150 and just purchase a complete running 200 looper. You can find them pretty reasonable nowadays. That should definitely get you the extra speed and also is much easier to hop up. Good luck!!!

[EMDSAPMGR]

Your 150xp Is A 149 Cubic Inch Engine Which Should Put Out 162-165 Horsepower. Two Prior Posts Recommend The 235 Or 175. Both Should Be The 160 Cubic Inch Variety. These Are Strong Engines. In Addition To The Required Change Of The Before-mentioned Exhaust Adapter Atop The Midsection, You Should Also Change The Exhaust Megaphone In Order To Maximize Your Hp Output. The 160 Inch Blocks All Use The Next Size Larger Carbs-1 3/8" Throats, So You Would Be Looking To Replace Them Also. Both Engines Will Use A Different Power Pack Than Is On Your 150. Look To Add 6 Intake Filler Blocks 322722. Add A Good Set Of Heads And You Should Get The Speeds You Want.

[bruce180vf]

I have been told this engine is a looper and a cross flow. My engine has 3 carbs centered in the intake. The pistons have the domed tops. It would be nice to know exactly which I have. The model # is E150SSTLE. This power head has supposedly been replaced at some point. the cylinder heads are prt#'s 328325 and 328324.
My block needs bored and I will have to buy new pistons so my option are open.I have found a 175 block and carbs. I will need to find the humped back exhaust plate mid and tuner. My crankshaft and rods are good. The power pack I have is the "t" shaped power pack and I think they should be the same as the 175 that year. Will the heads off my motor work on the 175 block, if I have them cut to raise the compression? I don't want to have a fortune in the engine but I know speed costs and how fast do I want to go. I am not in a hurry to get it done so I can look arond and find some parts. I would like to get 200 to 250 horse but the engine needs to stay looking like a 150. This maybe dreaming but. EMDSAPMGR i think you are right on the nose with the horsepower #'s.

[bruce180vf]

I found out my engine is a crossflow not a looper. :o

[gfinch]

Talk to Racer, He'll be back after Jan 2nd. if he makes it thru the Panama Canal.Vacation time.

Gary

[bruce180vf]

Thanks I will probably do that.

[neveredge]

A GT175 with the good heads will get you real close to 200hp at the prop, unfortunatly I just sold my last set of the good heads. If you are interested I can try and find another set.

In order to get anymore power out of a GT175 you are going to have to have it ported and there is no one better than Al Stoker. He can get you 240+ at the prop and still keep it reliable.

My GT175 pushed my 18' Ranger 361V above 70 mph. That is radar speed and the motor was bone stock. The GT 175's are strong motors and are closer to 190 hp than 175.

Good luck with your project.

[bruce180vf]

I wonder what it would cost to have him port it. I guess I will ask him when he gets back from vacation. My boat is stearn heavy and it definately could use more power. I thought about flipping the boat and putting a pad on it but I don't want to ruin the charger ride in the rough stuff and I dread the thought of undoing all of the rigging. So I think more power is the way to go. I guess if I really wanted to go fast I should buy a bullet or an allison.

[Lockjaw]

He told me to port mine, he would be able to do 80% on a bridgeport machine, which I think is a great way to go.

If you hunt you can find the heads, I found a set for 200 bucks, which is a good price, and got one extra one for 50.

The downside is I spent a bunch of money on them getting the vatted and blasted, and then I had to have broken nuts removed. Probably a salt water engine. I have all new stuff ordered for them, ie the sensors and all that.

Al told me that he could easily get me a reliable 235 hp to the prop, which is what I wanted. I don't think mine is putting out what it should be. But I am going to get it there, eventually.

Good luck.

[bigbore]

a 90 crossflow?it definitly is a crossflow if the intake and carbs are how it was described.a 90 150 xp crossflow thats strange to me.i had a 89 xp 200 that was a looper. :rolleyes:

[dynobo]

Bigbore, you are correct that your 200 was a looper. The 200/225 went to the looper design in 1986 with the 2.7 litre and the later to the 3.0 litre in 1988. ALL 150/175 prior to 1991 were crossflow and 1991 was the transition year that I believe both crossflow and looper were made in the 150/175 horsepower. Incidentally, I may be wrong here but, I believe all the GT/XP 150/175 were crossflow. I think the FASTSTRIKE name replaced the GT model etc.
Bruce, I think still for the money involved that you may be ahead of the game looking for a 200/225 looper to replace your 150. Much easier to MOd. and more HP potential. It will definitely get the speed you need and probably cheaper than rebuilding/replacing the crossflow.

[EMDSAPMGR]

You should have no problem re-using the power pack from your engine, but the 175 used a different part number. My guess is that the internal rev limiter is set lower on the 150 pack (probably 5800 rpm) than the 175.

[bruce180vf]

I have ported automotive racing heads for years but I don't know alot about porting 2 strokes. I know you can really mess up the port timing and have ruined the block and any gains you may have been trying to make if you get carried away. I would like to see some measurements or this 9 page report I keep hearing about. I am not scared to port my own engine ( actually I would love to do it, but some basic guidlines would help the process. I would love to go out and just buy the horsepower and hang on the boat but I do fish tournaments and it needs to be a wolf in sheeps clothing and the boat is rated for a 150. the boat is 17ft 10" and weighs 1400 lbs.

[jphii]

Here's a LINK (http://members.cox.net/aprilhorvath/StokerProject300.jpg) to an article Al Stoker did on making 300hp out of '90 200xp. I post this so you can get an idea about what is involved with porting a 2 stroke, and the possible gains. Also to show that you may be better off finding a looper and going from there.

[bruce180vf]

Thanks for the link it was very interesting reading. Correct me if I am wrong but a xp200 Is a lot taller engine and hood than the 150 and 175 crossflows. I think I would get pegged for sure by any omc guy at a tournament. The pictures are worth a thousand words. Thanks again all the information is helping make my decision of what to do.:)

[Lockjaw]

I don't think you would get pegged by anyone. Just stick 150 decals on it, and play dumb.

Since your engine is blown up, you can simply say, I got a smokin' deal on this engine, and since mine was blown up, I jumped all over it. ;)

[bigbore]

that was a while back even he probably has even more technicall equipment know no doubt hes the one.i would probably also recomend a looper also though bruce. :cool: