actual power difference... old HP vs. new???

[wexrocks]

Does anyone have a scientific or accurately estimated difference in HP between the older crank rated HP motors vs. the newer prop rated. like, a '80 Merc 200 compared to late '80s/early '90s Merc 200. actual "at the prop" difference? just wondering if I am really gonna gain the 30-40 HP that alot of people claim.

[donmac]

I don't believe there would be a way to calculate it, every gear ratio change,oil viscosity change or load change would alter propshaft readings. I think merc. changed from 225 to 200. would only apply to their gearcase and that specific design of case.

[transomstand]

I'm not convinced the advantage is that great, if any.

I ran an early 175, and a later model XR2 (about 160 at the prop) on my boat, the XR2 was slower.

In 1978, we ran a 200 on a Viper well into the 90's, and did the same with a Viking and Vandal a couple years later. Based on that experience, I think the difference in propshaft horsepower engines may be a little overblown.

[tj309]

I would say a rough estimate is 15% difference. For years Merc sold a 50HP and then it became the "Classic 45". On larger engines there was more of a drop. Like DonMac said - there are too many variables.

[whipper]

What did a 2.4 bridgeport wiegh? They were 240 HP wernt they? Anyone know the specs on these like limiter and such or is they came in a 15incher?

[The A Dog]

I've got a 1985 Merc 150...when exactly did they make the switch? Since it falls right in the middle of the 80's I was never sure if it was pre or post switch to rating HP at the prop.

[Dave Strong]

I have factory manual and sale brochure for 1990, man. says 363lbs, sales brochure says 335lbs for carb & EFI. Offshore 363lbs man, 360lbs brochure.
Mine had a rev limiter same P/N as the early 2.5 Carbs kicked in at 7700 RPM, it never worked so I removed it. As far as I know no 15" mid.
Dave

[tj309]

1985 was the year most Mercs were propshaft rated I think.

[whipper]

I have factory manual and sale brochure for 1990, man. says 363lbs, sales brochure says 335lbs for carb & EFI. Offshore 363lbs man, 360lbs brochure.
Mine had a rev limiter same P/N as the early 2.5 Carbs kicked in at 7700 RPM, it never worked so I removed it. As far as I know no 15" mid.
Dave
Thanks:thumbsup:

[tlwjkw]

:iagree: What Tstand said....

Comparin' apples ta apples (2.0 ta 2.0 etc) there aint no difference till ya get ta tha 2.5 motors. First generation motors (crank rated) ran just as good as any, some ever better. Book horsepower don't mean nothin' till ya bolt it on something n put both feet on tha floor.....................JMO

:thumbsup: Tha old 175 is a sleeper(if it still has all its chrome)......................:reddevil:

[wexrocks]

I guess Merc did not change much then... I was considering going Merc, and was curious how a newer 200 would compare power wise to the last one ('79) I had. I may stick with Evinrude then, I have a '80 175, and when Evinrude switched, they basically put a 175 sticker on the previous 235, from what I understand, and that would be a 60 HP jump (at the crank) which would be a big jump in a same size/weight motor.................. right? unless the 175 bubblebacks were detuned...... I'm sure someone has experience with this.

[tlwjkw]

I guess Merc did not change much then... I was considering going Merc, and was curious how a newer 200 would compare power wise to the last one ('79) I had. .

If tha NEWER 200 is a 2.5 then yes you would see a difference...........

[Ronny Jetmore]

how does this relate to omc numbers?

[tj309]

Probably about the same.

[wexrocks]

as far as OMC, I'm not sure about the smaller motors, but like I said, the newer 175 is the older 235, so thats a pretty big jump. I was trying to figure out if the Mercs were a big jump too, cuz I was considering going to a newer Merc 200 over a newer Evinrude 175, mostly for the extra power... but since most people have been saying the Mercs didnt gain much, I will probably go with a newer Evinrude 175, which apparently is way under rated and probably puts out a fair amount more than the Merc 200.

[tj309]

Back in the day Merc seriously underrated their motors whereas OMC did not. So when they went to propshaft HP ratings the Mercs did not change a whole lot like the OMC's did.

As far as the OMC 175 vs the Merc 200 comparison goes if it is pre '85 I would think the Merc is the stronger motor. What year are we talking about and what is the displacement of each motor?

[wexrocks]

displacement shouldn't really matter if it is fairly accurate HP ratings (lets assume)... what I have been trying to determine is what to go with... newer bubbleback 175, or newer Merc 200. I have run a few older Merc 200's, and was trying to find out if the newer 200's had much more HP. the newer 175 bubbleback is the older 235, and most have told me the old 235's put out way more than the old Merc 200's, which makes sense based on what I've seen. so, since the newer Merc 200's didnt change much, seems the bubbleback 175 (old 235) is the way to go. and since I am rigged for OMC, I wanted to make sure I was not sacrificing power by staying OMC. I was willing to switch (as I really have no brand preference after all the different motors I've had) to Merc if it meant more power. sorry about all the new/old, this/that. just gathering all the best info I can, and what better place??? :thumbsup:

[Bryan1257]

I`m confused!!!:eek::eek::eek: I do what the sticker tells me:D

[ssent]

This is easy, 2.5 200 Merc is the way to go. If you want to build more hp later the 2.5 has lots more possibilities/parts available. If fuel economy is an important factor for you, the loop charged merc is gonna be better verses the cross charged omc.