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stang72 
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 Topic: Horse power questionPosted: October-05-2005 at 1:45am |
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Why the different horse power rating on same engine??? (351 Waukesha...255 ,...351 PCM ...240) (302 waukesha...215 , ...302 Crusader..220)etc... Same engines different HP???
Also...just brought home a 72 Nautique (promo)...told it has a 302 (Waukesa)...Ran it for a test drive and it really jumped up and flew! Ran strong and fast!!! Most 70's SN's I have been in , are equipted with a 351...if this is a 302 powered boat , I can't tell a diff from a 351? It was much stronger than my Mustang(302). Maybe at some point a rebuild bored out??? How much different would there be between the two(351 vs 302)??? |
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stang72
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Posted: October-05-2005 at 10:08pm |
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Anyone???
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reidp
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Posted: October-05-2005 at 10:46pm |
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Good question(s) Stang. As for the 302's, in most cases, they're not just the same size-wise, but every internal power making piece is identical in regards to the 215,220,and 225HP 4V-302's. The exhaust differences may account for something, but I think it's just the marinization company's decision to put the number at a particular figure. They buy/bought the identical long block marine package from Ford and added their components. In most of their very earliest earliest years, Holman Moody did offer a premium fuel 4V package that was rated at 225HP/289, 235HP/302 and 290HP/351. But even those were short lived.
As for the 351's there was a head performance change when they went to the small spark plug heads after around 78-79(?), which essentially are 302 heads valve size-wise, and you saw the HP drop to the 240 range on many engines. Previously, the 351s AND 302 4Vs used the same head, as evidenced by many 215-220-225HP 302 owners noticing the "351" casting into the head under the valve cover. And this coincided with most original 302 4Vs having the same cam and firing order as a 351 as opposed to the older original 289 F.O. Make any sense? But like the 302s, even with the same internals, we saw 351 ratings at 250,255,260,etc. In regards to you new purchase (congrats!), since you also already have another 302, I guess you've verified that this is indeed a 302 and not a 351. Only reason I say this is that I have a great neighbor with an excellent 77 SN, which he's had since 85, and up until last year he thought it was a 302. Don't ask, and I won't rat him out. I never paid close enuf attention, just going on his word and never studying his engine that well. But I could never figure how it ran so damn fast and could hang with my 302 Mustang. |
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stang72
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Posted: October-05-2005 at 10:57pm |
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ReidP...I am trying to determine if it is a 302 or 351...I do have a 302 and a 351 to compare.Not sure what to compare though???I have not had time to really check it out sense returning home....
I spent a couple hours buffing some color back to see how much orange would return(by hand)!It's comming back pretty well!!! Gonna use a high speed rotory this weekend.I know you have done some of that 
Do you still have that yellow promo? |
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reidp
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Posted: October-05-2005 at 11:11pm |
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At a glance the 302 and 351 always look the same, but it's easiest to measure across the intake manifold between the heads. 351 will be noticably wider.
I love that orange hull...... We still have the yellow promo boat which I partnered with a friend and which has recently been painted, but which I haven't seen yet. Pictures Lance..? |
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stang72
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Posted: October-05-2005 at 11:23pm |
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Ah ha...it was Lance who like me did not know which engine!!! (just a guess)
Thats what I am looking for....a simple measurement...thanks! So with flash light in hand and tape...I am headed out now! Back to the first question...you think the mariniziation Co. may have just took a wing at it! Post pics of that yellow SN!!! How many in the fleet now? |
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stang72
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Posted: October-07-2005 at 1:42am |
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302 it is! I am surprized...I can't say I notice any power diff. from the 351's I have driven.
So...on a 302..if the heads are the same...cam and firing order as a 351....is there really much diff??? Where does the extra so called 20 HP in a 351 come from? 
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Bill336
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Posted: October-07-2005 at 2:01am |
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Not sure, maybe just the displacement difference accounts for it.
I have a Merc 198 which is a chevy 305 block. I did some research and found that it is identical to a 228 HP and I could convert it to the 228 by switching the 2 bbl carb and intake to the 228's 4 bbl carb and intake. |
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GottaSki
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Joined: April-21-2005 Location: NE CT Status: Offline Points: 3333 |
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Posted: October-07-2005 at 2:08pm |
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1/2" more stroke, taller deck
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole |
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reidp
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Posted: October-09-2005 at 12:32am |
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Bill336 and GottaSki are right on with the extra stroke and subsequent displacement feedback. With the same internal components, more CI's will certainly result in more torque and HP. The 302 in that boat is more than likely turning less prop than the 351 (13x12 vs 13x13) which will compensate somewhat for less cubes, but which should ultimately and naturally limit the top speed to less than a 351. I would expect a 220HP/302 to be somewhere in the neighborhood of 3-5 mph slower than a 250HP/351.
Bill336, I'm not sure on the 305 Chevy, but on the 302 Ford there was typically a head and cam difference also between the 2V and 4V engines. Drop one on there and see what it does. If there's a 30HP difference, you should see a good 3-5 MPH increase also. |
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stang72
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Posted: October-09-2005 at 2:06am |
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well ...yes it would seem that way...however I
am challanged to see how much actual difference there really is...I think 2 to 3 mph top end diff. Here's another comparison...my 72 Mustang with a 302 with gt40 heads, hits 47 to 48 mph top end...the 72 Nautique is 46 to 47 mph top end and quicker on plain!.I have calibrated the speedos...they are pretty accurate. The wieght diff between the two is 350 lbs.That is rather puzzling that there is very little diff in performance between the two??? The Mustang has 600 hours....I don't think the engine has gone through a rebuild....the Nautique...has 1100 hours(meter still ticking)...I assume it has gone through a rebuild...maybe heads ported or bored??? Don't know! I would have thought a nautique with a 302 would hit 45 mph max(maybe)...but it's exceeding that! I would be currious to see what others who have a nautique with a 302 have experienced performance wise...problem is...most have the 351. I could be way wrong here...but I am suggesting there is little diff. between the two! Just FOOD FOR THOUGHT!!!
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79nautique
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Posted: October-09-2005 at 12:42pm |
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even thought you think the speedo's are acurate they aren't. you need to use a GPS to look at top end speed. You are hitting the upper limit of the speedo and they will not read right, at slower skiing speeds they will be.
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stang72
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Posted: October-09-2005 at 3:11pm |
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79...your right and I figured I would hear GPS.
So..yes I am not getting real results.How much do those things(hand held) go for? I do plan to get one...it's on the want list. Whats your guess on the HP diff? |
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GottaSki
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Posted: October-09-2005 at 9:35pm |
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Since the 351 shares basically the same heads a 302 can run higher rpms before the restrictive heads limits its cfm. Therefore if the boat is light enough, a well propped boat can run faster with the 302.
A Heavier boat, the extra torque of the 351 will have a stronger holeshot with a skier's load. The basic, non-gt40 351 goes soggy above 4200 rpm, the 302 goes soggy at a higher rpm. |
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole |
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stang72
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Posted: October-13-2005 at 12:14am |
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GottaSki...Thats pretty much what my buddy who owns a performance machine shop is saying!
Said the same about a 327 vs a 350 chevy (in cars). |
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