1981 V4 90hp vs 1987 70hp

[Jill_S]

Just looking for some opinions here. If you had a choice between these two motors which would prefer? Which motor would you consider to be more reliable in your experience or obversations.

Deciding factors. Both run with good compression and no lower unit water intrusion problems. The 1981 90 hp was used the first 8 years then properly put in storage for the last 18. The previous owners worked for Chris Craft. The extra hp would be nice but not necessary. I like the idea of the low hours on the 90hp but also think maybe a newer motor might be better. 90hp is $250 cheaper. Both fresh water motors. I've heard rave reviews on the 70hp Johnsons but not much on the 90hp. The 70hp has a connected VRO setup which would be disconnected if purchased. 70 hp also has been freshly painted including under the cowling which make me suspcious but I could be entirely wrong.

I'm having trouble making up my mind so I'm seeking input from others with a better knowledge of the newer motors. I'm only familiar old motors from the late 50's to late 60's like Fat Boys, Big Twins and Super Seahorses from 35hp to 75hp.

Thanks

 

[rickdb1boat]

Re: 1981 V4 90hp vs 1987 70hp

My concern would be with a motor that has sat for 18 years. Seals, Rubber, Electric components, Etc. dry rot, internally and externally, from non-use. Both are superb engines that would be very reliable. But if it was me, I'd shy away from the 90..

 

[Chinewalker]

Re: 1981 V4 90hp vs 1987 70hp

Hi Jill,
You can't really go wrong with either motor, but consider you'll probably have to have a top to bottom tune-up done on the 90 before using.
If the boat is heavy or will be carting a heavy load, then the 90 is probably the way to go. If it's lightweight and you're just in for cruising, then the 70, with it's considerably better fuel efficiency, might be the way to go.
- Scott

 

[Jill_S]

Re: 1981 V4 90hp vs 1987 70hp

Hey Scott....how it going? You know me from that other site.

The motor will be going on my 1959 Glasspar Sedan.

 

[HighTrim]

Re: 1981 V4 90hp vs 1987 70hp

Jill what is the max hp rating for that boat?

 

[Jill_S]

Re: 1981 V4 90hp vs 1987 70hp

I believe 120 max hp. Recommended is between 75 to 100. Boat weighs less than 2000lbs 17' in length. Width don't know off the top of my head.

Boat came with a 1960 Fat 75. I've seen other happy owners with 55hp and still gets up on plane...or is it plain?:redface: I'd like to pull skiers, mostly kids but would like have the power to get 200lb plus adults/teen up too.

I want something that will hopefully be more reliable but I do realize they both are still over 20 years old. Both motors have tilt trim which is another necessary feature. Don't want to have to heft the motor up anymore when beaching.

Fuel efficiency, within reason, is a minor issue. Boating is an expensive hobby and saving an estimated $20 to $40 bucks on a weekend trip is a drop in the bucket in my opinion. But then again with todays gas prices my view on that may change.

Jill

 

[kenmyfam]

Re: 1981 V4 90hp vs 1987 70hp

With 120hp max you would be at 75% of your max hp with the 90hp. With 70hp you are a little under 60%. Personally I would be going with the 90hp for the extra power and the fact that you are planning to pull skiers.
My thoughts are that if you have more than you need you do not have to use it all but if you do not have enough then you will be looking for another motor.
I have 140hp on my 164 Doral (max) for that hull but I do not use all its avilable power most of the time.
Good Luck with your decision, I hope it works out for you.
By the way, both are great motors.

 

[HighTrim]

Re: 1981 V4 90hp vs 1987 70hp

Actually these 2 motors are fairly close in hp due to the HP rating change in 85

The 81's hp is rated at the crank and the 87's is rated at the prop.

I doubt you would notice any difference at all between the two. The price difference of 250 bucks would be put into the 90 anyways to get her running after 18 years of sitting anyways.

 

[iwombat]

Re: 1981 V4 90hp vs 1987 70hp

Remember - '81 was crank rated, '87 was prop rated.

The horsepower is roughly the same, give or take 5hp.


Edit: D'oh - HighTrim was faster on the draw.

 

[kenmyfam]

Re: 1981 V4 90hp vs 1987 70hp

Right you are but I just love those V4's !!!!

 

[kynolan2183]

Re: 1981 V4 90hp vs 1987 70hp

I have an 1984 70 hp and with a 200 lb tuber it takes longer than I like to get on plain. I have it on a 17 footer 1500 pound total weight boat. My hp rating is 90hp and I often wonder what the boat would do with a 90 hp. On take off it is the torque that gets in going and the 90 will have more than the 70.

I personally think that you would be wishing you had the 90 when trying to pull up skiers but the gas mileage on my 70 still competes with todays newer motors. I run about 6 gallons an hour at wide open at 35 mph and run about 4.0 gallons an hour at 28 mph.

The 70 hp will be lucky to get that heavy of a boat to 35.

Kyle

 

[ezmobee]

Re: 1981 V4 90hp vs 1987 70hp

Awesome looking boat!

 

[Jill_S]

Re: 1981 V4 90hp vs 1987 70hp

Thanks a bunch folks for the great info. Mostly that the hp rating is not much different between the two. I'm in no hurry and can let these motors go but thats what I had narrowed it down to. Also glad to hear they are both good motors. Definately concerns of a motor that has been sitting 18 yrs.

One more question? What is the weight difference between these motors?

Thanks for the compliments on my boat.

ezmobe....is yours aluminum? Nice too.

Jill

 

[ezmobee]

Re: 1981 V4 90hp vs 1987 70hp

Mine is aluminum. And after reading all the threads in the restoration section I am thankful for that daily!! Going to have to do my transom here shortly though.

 

[HighTrim]

Re: 1981 V4 90hp vs 1987 70hp

The 81 is roughly 300 lbs and the 87 is about 257 lbs

 

[emdsapmgr]

Re: 1981 V4 90hp vs 1987 70hp

While the hp ratings are nearly identical due to the methods of rating each, you should consider the torque differenc. The 70 is something like 56 cubic inches, the 90 is 100. There is a lot more holeshot capability with the 90.