Evinrude 9.5 vs 8hp speed test

[Evinrudej]

What’s up everyone I just picked up an 8hp evinrude 1985 that I am going to be trying out in a few days. I have never used the 8hp so I don’t know speed wise what I’ll be getting on my 11ft aluminum. I have seen many say it is similar to an evinrude 9.5 speed wise. Is this true? Thanks.

 

[jimmbo]

Depends on what a persons Idea of Similar is. It is only a 1 1/2 hp difference. What are you currently using on the Boat?

 

[Evinrudej]

Depends on what a persons Idea of Similar is. It is only a 1 1/2 hp difference. What are you currently using on the Boat?

Currently using the 9.5 gets about 18-19 mph 11ft semi V hull

 

[saltchuckmatt]

The 8 HP will move an 11 boat pretty fast once on a plane. Top end will be similar but out of the hole the 9.9 will be better. Block size, carb bigger on the 9.9 so it makes sense. If you fish and stuff the 8 is the motor to have

 

[jimmbo]

Currently using the 9.5 gets about 18-19 mph 11ft semi V hull

The 9 1/2 was no speed demon, and was last produced in 1973, and was definitely Crank Rated. The 8 was made during the Time Period where OMC was switching to Prop Ratings. There may have been some improvements in Hydrodynamics of the 8hp gear housing and propeller design compared to the 9 1/2.
The 9 1/2 has about 15 cu in displacement, while the 8 has 10 cu in, but the 9 1/2 is rated at 4500 rpm, while the 8 is rated at 5500.
I would expect a serious difference in Performance between between the 8 and a 9.9 of the same year, but between the 8 and a 9 1/2, I don't think the difference will be all that great. Likely less than 1-2 mph difference with a light load

 

[flyingscott]

The 9.5 was a 7.5 in disguise. It was not powerhouse.

 

[jimmbo]

The 9 1/2 had little in common with the 7 1/2, perhaps the gear housing. Powerhead was way different

 

[flyingscott]

The 9 1/2 had little in common with the 7 1/2, perhaps the gear housing. Powerhead was way different

I meant in the way of power production

 

[909]

They're called turtles for a reason. They're low compression and crank rated. Mine felt more like a 5 lol. But it's light, compact and folds right up to fit in small spaces ( like float planes where space and weight matter most ) .

Your 8 has higher compression & rpm as mentioned. It's newer (generally more reliable) , and prop rated. I would keep the 8 if it were up to me, but then again if I wanted to go fast, I would just get a newer 15hp ( 1993 to 2007) if speed was my goal .

 

[Crosbyman]

The 9.5 was a 7.5 in disguise. It was not powerhouse.

deleted

 

[racerone]

I worked on a lot of those 9.5 models in those days.-----Nothing wrong with the motor / concept in the day.---The expectation of folks is just different today.

 

[rolmops]

I do not know the exact year, but up to a certain date OMC measured the Horse power rating at the engine drive. Then they started measuring at the propeller shaft and the horse power measured there was always less. For example, the 2 cylinder 35 horse became a 33 horse. In 1985 power was already measured at the propeller shaft, while in 1973 it was still at the drive shaft. This does not mean that it is the same engine. Since 1973 a lot of changes were made on these little machines

 

[racerone]

??---Fact for you !!------The 28 HP built from 62 to 64 became a 33 HP in 1965.

 

[JimS123]

I have a 1970 9.5 on a 14' tinny. One vacation I replaced it with a 1984 9.9. The difference was negligible.

One thing I can say about the 9.5, though. It simply runs and runs and is probably the best OB I ever had.

 

[Crosbyman]

great kicker for trolling and emergency back-up to modern technology

but... I replaced it with even better gas guzzling wise anyway a nice Merc single cyl. 4hp

 

[jimmbo]

The 57-59 35hp and the 33hp had the same bore and stroke/displacement(40.5 cu in) and were rated @4500rpm
The 1956 30hp and the 28hp had the same bore and stroke and displacement(35.7 cu in), and were also rated @4500rpm
That is not to say the 35 and 33 used the same Blocks, same goes for the 28 and 30 hp.

I guess they could have used the 40.5 cu in block with thicker Sleeves in it to reduce the bore by 3/16", making it a 35.7 cu in Displacement to make the 28hp

 

[saltchuckmatt]

great kicker for trolling and emergency back-up to modern technology

but... I replaced it with even better gas guzzling wise anyway a nice Merc single cyl. 4hp

I know, I can't believe you did that....stooped to a Merc!

 

[Crosbyman]

something in me was left over.... from my early days of boating in the late 60s

 

[jimmbo]

I grew up in an OMC Family, but I found Mercs to be good, well made Engines, which in most cases, usually out performed the OMC models of the same labeled HP

 

[saltchuckmatt]

Yes, they put performed them in performance unless you couldn't get them to start!

Just saying.