160hp I6 mercruiser to v8?

[Don S]

Lots of things would have to change, Exhaust Y, Merc exhaust system for V8, gear ratio change in drive.
All the electrical and fuel system parts would have to be upgraded to marine for you V8, it's it's now an automotive engine.

 

[Don S]

Re: 160hp I6 mercruiser to v8?

I didn't say the electrical and fuel system parts "SHOULD" be upgraded, I said the HAVE to be up graded.
The carb, fuel pump, distributor, alternator, and starter to name a few, MUST all be marine specific parts. It's a safety (Fire & Explosion) issue for not using the automotive parts.
You also need a marine exhaust system, even with thru hull exhaust.
You MAY be able to get a prop that will work, but it won't be very efficient, that is why they have different gear ratios.
Your IL6 uses a front engine mount, the V8-s have side mounts and bolt to the stringers.
You would also need an inner transom shield as the mounts are different for a V8, same with bellhousing and coupler.

 

[Bondo]

Re: 160hp I6 mercruiser to v8?

would it easily pull a skier?

Ayuh,........Sure Will......

That Alota motor for a small boat.......

 

[thunderroad]

Re: 160hp I6 mercruiser to v8?

The above post was mine too. I haven't got this board figured out yet. I made one post earlier and got a message that said..."This forum doesn't exist"....strange..
Anyway...about top end speed. My 160 in a 19"6" boat will run about 35 or so if you want to trust the 37 year old speedometer. I don' t run it at quite WOT because it just feels like I'm running it too hard and I really can't see that the last 500 rpm's make much difference in top end speed....plus I ain't really in any hurry so what the heck, right?

 

[Almeja]

Re: 160hp I6 mercruiser to v8?

A correctly propped 160 should give you mid 40's at least in a 'typical' runabout.

Inherently smooth engine.

 

[thunderroad]

Re: 160hp I6 mercruiser to v8?

I've been told.....but not necessarily by an impeccable source....that other than the cam, the 250 cu in I6 is basically a GM truck motor.
I'm sure others here can tell you for sure.

 

[peacekeeper6]

Re: 160hp I6 mercruiser to v8?

i have an extra I6 motor in the back of my truck that you could buy off me or use, i havnt heard it run but it was included as a spare motor and turns freely.

 

[Silvertip]

Re: 160hp I6 mercruiser to v8?

No -- the 250 six is not a truck motor. It was used in light duty pickups but served as a passenger car engine for years. It started life in the 1960's as a 194 cu in engine. Then 230 then 250. If you want some extra beans, use a Chevy six cylinder truck engine which was the same basic engine but at 292 cubic inches. Long stroke motor so it would have gobs of torque on the bottom end. You should not have to change mounts or exhaust components. Even the 250 electricals would work. You may need to tweak the carb however for the added cubes.

 

[HT32BSX115]

Re: 160hp I6 mercruiser to v8?

I considered swapping out my 230 cu-in (Merc 150) in my 66 Marktwain for either a 250 or 292.

The easiest swap would be the 250 cu-in engine. Most everything will interchange and you can use the orig cyl head. If you use a truck engine you'll want to ensure that you install the correct freeze plugs and marine cam etc. I also considered a 292. The 230/250 head will fit on a 292. it changes the comp-ratio though... The 292 engine is approx 2 inches taller.... Also, it looked like the vib-dampener on the 292 might interfere with the Mercruiser front engine mount. (In the 1966 Mercruiser 292 cu-in engine, it appeared in my service manual that they used different engine mounts than the 230 cu-in engine).


If I hadn't sold my 66 MarkTwain (in the family since new) I would have either rebuilt the 230 or replaced it with a 250.

What ever you do, don't try to price a new replacement aluminum or cast iron exhaust manifold! The price will scare you!

(Of course I jumped out of the frying pan right into the fire with the OMC 7.5!! but 2 manifolds for a 7.5l OMC are "only" $1000 each vs nearly $3000 for the 150/160 Mercruiser in the Doug Russell catalog!!!)


Regards,

Rick

 

[SteveNix]

Re: 160hp I6 mercruiser to v8?

my I6 will pull me (170lbs) up slalom with 6 ppl in the boat no problem with my 17P prop.

 

[DukesFin]

Re: 160hp I6 mercruiser to v8?

FYI - I just got done rebuilding my L6... It is on a 21'2" Cuddy Cabin (Grady White '74 model) and running at 4000 RPMs, I'm hitting about 33mph. That fast enough for you? Should be. I've got a Holley 4bbl on it and best guess is I'm pushing 170-175hp on her.

Stick with the L6, not because I have one, but I don't want to have to recover your charred body or those of your friends on the water. Your boat was made for the L6. If you do want more power, think about getting a bigger boat or one that is made to handle the increase in power.

Not to mention the safety, the transformation would cost $$$$!!

 

[imported_Tinboat]

Re: 160hp I6 mercruiser to v8?

The I-6 is a GM 250CI, BUT, Gm made these blocks for Mercruiser, and at the very front of the block there are BOLT bosses that are not present in automotive applications.....ran into this prob a few years ago helping a friend upgrade to a 292......had to do some VERY intense rigging to get the front Mercruiser mounts to kinda sorta fit....Stay with the 160 and rebuild it. The only difference between a 160 and a 165 is the Intake/Exhaust manifold. The only one available is the 165, and it's pricey, but it flows better. (thus 5 extra HP)

Hope this helps.