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Author Topic:   Suzuki 70 vs Yam/Mercury 75
kysard posted 06-08-2002 10:26 AM ET (US)   Profile for kysard   Send Email to kysard  
Anyone have experience with the power of a suzuki 70 vs. the merc/yammy 75 4 stroke.
jimh posted 06-08-2002 04:26 PM ET (US)     Profile for jimh  Send Email to jimh     
The Mercury 75-HP 4-stroke is the same displacement power head as the 90-HP variant, while the Suzuki 70-HP 4-stroke is same displacement as the 60-HP variant.

Let's compare the cubes:
Mercury 75 = 97.4 cu-in. (1596 cc)
Suzuki 70 = 79.2 cu-in. (1298 cc)

That is 23% more displacement in favor of the Mercury engine.

Let's compare the weight:
Mercury 75 = 386 lbs. (175 Kg)
Suzuki 70 = 342 lbs (155 Kg)

That is 13% greater weight for the Mercury engine.

Based on this, you would expect the 75-HP Mercury to probably have more guts than the 70-HP Suzuki, but it weighs more.

It should also be noted that the Suzuki 70-HP has electronic fuel injection while the Mercury engine carbureted. On the other hand, if don't mind the price, you can get the same powerhead in the Mercury engine with EFI with a horsepower boost all the way to 115-HP rating! Of course, there is likely to be quite a price to pay (in dollars, literally) for that step up.

JBCornwell posted 06-08-2002 06:48 PM ET (US)     Profile for JBCornwell  Send Email to JBCornwell     
I have no arguments with JimH's analysis.

I think we agree that where the prop meets the water it is torque that makes it go, and torque correlates well with displacement. Of course there are the other factors, like EFI, tuning, etc.

A factor that is important, though, is the vessel. Dependng on where you anticipate mounting the engine there may well be other options that deserve consideration or may even be clearly a better choice than either of the above.

What do you anticipate putting it on?

Red sky at night. . .
JB :)

kysard posted 06-09-2002 07:24 AM ET (US)     Profile for kysard  Send Email to kysard     
I'm a gearhead (cars). I agree with the analysis but one thing: EFI traditionally improves low range torque over a carburator.

Now we know when you put EFI on a 97.4 cuin block Merc you get 115 hp. So Suzuki with its 79.2 cuin block with EFI should be a solid 70 comparable with the Merc 75?

This would go on a 19 ft outrage II. I am a troller so I need to idle smooth. I fish big water (near-shore MD) and skinny water (rocky susquehanna river.) It is a lot to ask of a boat. Been looking at the Tohatsu 90 HDLI? because its lighter weight but not sure how it would idle being a 2 stroke.

jimh posted 06-09-2002 08:47 AM ET (US)     Profile for jimh  Send Email to jimh     
Oops--I have mislead you on the 115 EFI Mercury. It has also been stroked slightly to boost the displacement to 106.2 cu-in. (1741 cc). Otherwise it appears to be the same engine as the 70/90; the weights are the same.

I think this same powerhead is also the Yamaha 80/100 4-stroke duo.

JBCornwell posted 06-09-2002 09:54 AM ET (US)     Profile for JBCornwell  Send Email to JBCornwell     
Howdy, Kysard.

I wouldn't put a 70 or 75 on a 19 OR2 unless it was one of a pair. But, I think twin 4 strokes weighing 350 or more each would be too much weight for that boat.

I think that the EFI 115s offered by several makers would be a much better choice, or even the Big Suzi DF140 or Honda BF130.

Good luck.

Red sky at night. . .
JB :)

Bigshot posted 06-10-2002 09:51 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
A 70 on a 19or? Would it get on plane? Are'nt you under the min rec HP?

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