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harbormaster
11-08-2007, 07:23 AM
Hello everyone.

I was in Las Vegas last week and got a peek at Mercruiser's latest offering.

It's a 400hp 383 scorpion. I comes decked out with billet valve covers and a flamed theme (see photos). It also comes with some nice internal components. It's currently only being offered as an inboard/transmission configuration for the skiers. The scoop is however that it will be available in a Bravo version in February. I have enclosed a pre-release brochure. (begin tasteless Plug) Oh yes and did I mention that I could sell them to you? Call me at Victory Marine 713-910-2000 if you have more questions. I am working on getting pricing.

Ranman
11-08-2007, 08:28 AM
Looks like a nice motor. 400CSHP @ 6000RPM is interesting. I bet the Bravo version wil have to be tweaked since Bravo's don't like 6000RPM. Also the PSHP would be around 360. Still very solid, but I bet not far from the standard 6.2MX when tuned down to 5000RPMs.

Lenny
11-08-2007, 09:46 AM
Is that a carb motor?

harbormaster
11-08-2007, 11:56 AM
fuel injection

RickSE
11-08-2007, 11:58 AM
The inboard guys get all the good motors. They've got the new GM small blocks.

Trueser
11-08-2007, 12:12 PM
How much $$$$$

Cuda
11-08-2007, 04:11 PM
What's the torque graph look like?

Pismo
11-08-2007, 06:06 PM
What's the torque graph look like?


That could be a weak point. If it needs 6000rpm to get out 400cshp then 2500rpm torque may not be so hot. It sounds like a cool motor for a lighter fast boat, like an 18 classic, but I'm sure the low end torque numbers don't match up to a 454/496/502 which has about the same top end hp.

BigGrizzly
11-10-2007, 11:13 AM
Merc isn't that stupid, it is a ski boat motor, so torque should be up there at low rpms.

Cuda
11-10-2007, 03:22 PM
Merc isn't that stupid, it is a ski boat motor, so torque should be up there at low rpms.
They are probably geared down for ski boats, and run a small prop, I just don't see an engine that spins 6000 rpm for max hp, having much low end grunt.

BigGrizzly
11-11-2007, 08:14 AM
On my Criterion the max torque is 700lbs @ 3,977 and max power is around 5,600, still climbing but I ran out of intestinal fortitude and shut it down. The Corsican with a 351 Ford 351 V4 big port,no less, has max torque at 3,200 anf hp at 6,100(which it never sees). That boat comes out of the hole real well. I have never tried to push the Criterion because it will lunch the transmission and or the outdrive. It has 500lbs at just over 2,200. Point is it can be done easily if the correct cam and piston combination is used. Things have changed in the past Decade. If I knew in the 1970's what I know now I could have won the Daytona 500 with one gas stop. when I was a kid one horse power per cubic inch was a radical engine. Today it is commonplace on regular gas!

Cuda
11-11-2007, 09:07 AM
351 Ford 351 V4 big port,!

Big ports is an understatement! The intake valves were 2.19. I don't know how big the ports were, but you could drop a crescent wrench in it! They were huge!

My dad had a couple 351 C's, and they never would run as well as you would think. My buddy even had a Boss 351 he bought just to beat my other buddy's basically stock Nova 350, and still couildn't beat him.

I had a 69 Mach I with a 351W, and it was faster than any of the Clevelands.

I think the ports, and valves were just too big for a basically stock engine.

BigGrizzly
11-11-2007, 09:45 AM
Cuda you are correct on the original stock versions. The engines were designed for sustained high speed operations ie. Lemans 24 hour. In the street versions the had two heads the big port open chambered and closed chambered head. I am not including the small port Clevelands, which are not too bad.
At this time the were down HP ing the auto industry. As a result the cams were poor to say the least. H&M put them in some boats. They had two configurations. One a bib port small valve (only a few made) amd big port big valves. Didk Edelbroc and Ed iskaderian and Babe Erson got together to make cams and intakes tor Dick's Pantera sports car. I have been friends with Babe since the mid 1970s, and he hooked me up. Took the stock cam out on my 71 MACHI and put in Babe's max 108, and a different car. BTW I still have the MACHI. If this motor can be made to work, I am sure that the Scorpion can. Also my fuel economy is a lot better than stock too.

Pismo
11-12-2007, 09:21 AM
Merc isn't that stupid, it is a ski boat motor, so torque should be up there at low rpms.

I can't say it's a question of stupid or not, it's just tough to get the same torque curve out of a 383 as opposed to a 502.

BigGrizzly
11-12-2007, 04:22 PM
The 351 Cleveland has more torque than a 350mag does the point is it is stwrting out for ski boats ie Mastercraft, ski Nautic etc. Can they do i-YESW- will they time will tell.

Cuda
11-12-2007, 10:42 PM
I can't say it's a question of stupid or not, it's just tough to get the same torque curve out of a 383 as opposed to a 502.
Torque is more linearly linked to cubic inches, than horspower it.

VetteLT193
11-13-2007, 07:58 AM
I can't say it's a question of stupid or not, it's just tough to get the same torque curve out of a 383 as opposed to a 502.

Comparing a 502 to a 383 is a tough comparison no matter how you look at it. And, it's all speculation until all the numbers are available.

I think the way to compare it is dollar for dollar, pound for pound, and look at the area under the curve.

It does look like one sweet engine:)

BigGrizzly
11-13-2007, 10:46 AM
Who, I was using my 502 as a proportion, because I have all the numbers and countless hours of verified numbers on it My Cleveland is a closer representative of what we are talking about. Since the Cleveland is what I have and Cuda knowes how hard it is to get low end out of it I also used it. Most of you guys are too young to fully appreciate the real muscle car era. The question was the 383 may not have enough torque to perform well at lower RPMs. Answer is yes it can if don correctly! Just because it has a 6,000 red line, doesn't mean it has no torque at lower R's. Yes on most applications it is easier to get torque out of a bigger displacement motor. Just in case you guys for got a 383 is a lot bigger then a 350cid and fact is it can get better volumetric efficiency than a 350 due to the bore stroke ratio and some other minor details, I won't get into here.

p729lws
11-13-2007, 02:47 PM
Did the old Scorpion motor require 91 octane fuel also and does anyone have access to it on the water where they boat? I guess its not a big deal to the trailer queen crowd.

Dan

VetteLT193
11-13-2007, 03:25 PM
Did the old Scorpion motor require 91 octane fuel also and does anyone have access to it on the water where they boat? I guess its not a big deal to the trailer queen crowd.
Dan

All they sell by me is premium at the dock. I think they do it so they can charge even more $$. :eek!:

BigGrizzly
11-13-2007, 04:41 PM
The have 91 here on Lanier and on lake George as well

Cuda
11-13-2007, 07:24 PM
Most places I've seen on the water in Florida only sell midgrade 89.

blackhawk
11-15-2007, 08:22 AM
Two engines making identical hp with one peaking at 5000 rpm and the other at 6000 rpm. The 5000 rpm engine will make more torque 99% of the time because it's peak is closer to the 5252 rpm crossing.

But I wouldn't worry about the low-end power of a 400hp 6000 rpm engine because it will have less prop to spin to the 6000 rpm which will also help the planing/low-end performance. As Ranman said i would be more worried about the drive!

BigGrizzly
11-15-2007, 09:17 AM
Engine combination is all I can say. BH 30 years ago your statement would have been true but today it is closer to 70->75% of the time. When I was doing this 20 years ago 750->800 hp out of a 540 CID normally aspirated would be unheard of. Today we do it and make it run on 89 octane fuel with 730lbs of torque at 3,200 with peak HP about 5,800. 383s are getting the torque of big blocks relatively easily. IF I only knew 30 years ago what I know now, and I am still behind some of the new stuff. I assume by 5,250 RPMs you were talking about the rev limiter on a 350CID engine which is controlled by the ECU. We have taken the rev limiter off the 350 mags and it still pulls past 5,500 RPMs. However torque drops off as it does normally on a stock unit. The combination is the key factor!

DonCig
11-15-2007, 09:45 AM
Engine combination is all I can say. BH 30 years ago your statement would have been true but today it is closer to 70->75% of the time. When I was doing this 20 years ago 750->800 hp out of a 540 CID normally aspirated would be unheard of. Today we do it and make it run on 89 octane fuel with 730lbs of torque at 3,200 with peak HP about 5,800. 383s are getting the torque of big blocks relatively easily. IF I only knew 30 years ago what I know now, and I am still behind some of the new stuff. I assume by 5,250 RPMs you were talking about the rev limiter on a 350CID engine which is controlled by the ECU. We have taken the rev limiter off the 350 mags and it still pulls past 5,500 RPMs. However torque drops off as it does normally on a stock unit. The combination is the key factor!

Randy, over the last year I have called a number of the popular marine engine builders and asked them all the same question; and I have received many different answers. What is your position on the following scenario and question?

First; the engine is a 454 built to have a fully stable valvetrain at a sustained 5,800 rpm. Compression ratio of 9.0/1
Carburated induction with a high flow dual plane intake manifold.

Second; the hydraulic roller cam was designed to produce peak torque at 4,000 rpm (477 ft/lbs) and peak horsepower of 425 at 5,500 rpm.

Here is the question that I have asked?

Where would you try run the engine rpm at wot? Should you try and prop the boat so that you can pull 5,500 rpm? Or should you try and prop the boat to achieve the fastest speed whick could possibly be at a lower rpm?

Thanks in advance,

Don

Last Tango
11-15-2007, 09:49 AM
To answer p729lws' question about Scorpion fuel requirements, to the absolute best of my knowlege, all Scorpion motors required Premuim fuel, regardless of whether they were a Black Scorpion or a Blue Scorpion, inboard, or outdrive. The Regular Fuel version is the standard MX 6.2 MPI. Same displacement (377 cu in) but different "stuff" for the Scorpion in order to increase the horsepower.
For the torque discussion, remember that Scorpions were offered FIRST to the tow boat folks, to replace the 454's.

BigGrizzly
11-15-2007, 10:11 AM
I do things a little different as you know. I am assuming this is for your use. I prop things for more than just top speed. I try to attack the handling and durability of the engine and drive train too. So here goes: My first question would be, is a shorty going to be used, the use-ski-cruise or racing, then determine to use a 4 or 3 blade prop then go from there. Do to all the different styles(profiles) available the torque and RPM question is ominous in the answer category. Like jetting, do the top first than work around the other areas. Regardless of the ability to sustain 5,800 or not, Rpms hurt many areas. At no point would prop the engine to run at 5,000 to5,050 rpms continuously! The fact that every boat is different adds another variable. So I guess my answer would be top speed to find out where the engine is really running in the application. It is a complex question given the information provided

DonCig
11-15-2007, 10:19 AM
I do things a little different as you know. I am assuming this is for your use. I prop things for more than just top speed. I try to attack the handling and durability of the engine and drive train too. So here goes: My first question would be, is a shorty going to be used, the use-ski-cruise or racing, then determine to use a 4 or 3 blade prop then go from there. Do to all the different styles(profiles) available the torque and RPM question is ominous in the answer category. Like jetting, do the top first than work around the other areas. Regardless of the ability to sustain 5,800 or not, Rpms hurt many areas. At no point would prop the engine to run at 5,000 to5,050 rpms continuously! The fact that every boat is different adds another variable. So I guess my answer would be top speed to find out where the engine is really running in the application. It is a complex question given the information provided

Randy, when I asked people like Tyler & Crockett along with some of the other major marine engine builders; most of them said that the would like to see their engines run right up to max HP rpm, a couple of the engine builders suggested 200 hundred rpm less than max h.p. A couple of the builders suggested propping between max torque and max hp, based on fastest speed obtained.
This was a hypothetical question and does not apply or any of my current boat inventory.

Thanks for your response.

Don

BigGrizzly
11-15-2007, 10:49 AM
T&C is giving a theoretical engine use applications the others are play ing it safe so the max isn't achieved under ideal conditions. I have seen too many mistakes made in either answer so I go the application route. With props it isn't just a dyno game. you heard it before. I have 450hp and my boat goes 60 mph. To be quite frank they were generic answers. In the real world It would be just shy of the HP rating. In other words if the max boat speed was 68 mph at 4,900 and 68 at 5,200 I would go with the 5,200 rpm prop. Yet I would not do 5500. Providing this engine is not loading up at this top speed. My Criterion has the approximately the same proportions od rpms vs hp. and I am propped at 5,200 RPMs. I do carry two props just in case that pesky little 20 Cigarette gets too fast for me.

blackhawk
11-15-2007, 05:48 PM
I assume by 5,250 RPMs you were talking about the rev limiter on a 350CID engine which is controlled by the ECU. We have taken the rev limiter off the 350 mags and it still pulls past 5,500 RPMs. However torque drops off as it does normally on a stock unit.

No. I am stating that torque is ALWAYS higher than hp under 5252 rpm. And after 5252 rpm horsepower is ALWAYS higher than torque.

Using the same example of two 400hp engines one peaking at 5000 rpm and one 6000 rpm. At 5000 rpm the higher rpm engine will be making less hp(and torque) than the lower rpm engine. Which is going to mean as we go down the rpm range the lower rpm engine will have more hp at a given rpm under 5000 IN MOST CASES. Obviously, there will be rare exceptions, but no too often.

If engine A makes 20 more hp at 2500 than engine B. That means engine A will be making about 40 more lbs of torque. It has too. Regardless of cubic inches, it has too.

I'm not saying a 6000 rpm 383 is a bad motor. I am only replying to the low-end torque posts. What I am trying to say is the ONLY way a 383 can have the same low rpm torque as a 502 is if it has equal low-end hp. And I am betting that a 400 hp 6000 rpm motor has less hp from 2000-4000 rpm than a 425 hp 5000 rpm motor. Not saying it's bad or good, just stating the facts.

MOP
11-15-2007, 10:24 PM
I built a fairly mild 383 under 400hp for my 22, I needed a boat that was a people hauler reasonably fast and economical (Ooops dirty word)! I use my boat for work and play, mine makes very nice all around power. I have spun it up to 5500, but found that by propping down to 5000 I got 2.5 miles an hour more and even better economy. My opinion is these 383's in "many" applications are slower but more versatile than a big block. I know of some that have made more power/speed but suffered in the lower more used ranges, to me it boiled down to durability I wanted a tough economical package and that I have. I bet we will see a few more 383's around, no they won't scare the crap out of your passengers but they will do the job of hauling them and cheaply.

Phil

VetteLT193
11-16-2007, 07:17 AM
No. I am stating that torque is ALWAYS higher than hp under 5252 rpm. And after 5252 rpm horsepower is ALWAYS higher than torque.
Using the same example of two 400hp engines one peaking at 5000 rpm and one 6000 rpm. At 5000 rpm the higher rpm engine will be making less hp(and torque) than the lower rpm engine. Which is going to mean as we go down the rpm range the lower rpm engine will have more hp at a given rpm under 5000 IN MOST CASES. Obviously, there will be rare exceptions, but no too often.
If engine A makes 20 more hp at 2500 than engine B. That means engine A will be making about 40 more lbs of torque. It has too. Regardless of cubic inches, it has too.


I'm sure you already know this, but for anyone that doesn't:

HP = (Torque x RPM) / 5252

That's why the HP and Torque curve lines always cross at 5252... It also explains what HP actually is.



I'm not saying a 6000 rpm 383 is a bad motor. I am only replying to the low-end torque posts. What I am trying to say is the ONLY way a 383 can have the same low rpm torque as a 502 is if it has equal low-end hp. And I am betting that a 400 hp 6000 rpm motor has less hp from 2000-4000 rpm than a 425 hp 5000 rpm motor. Not saying it's bad or good, just stating the facts.

While I generally agree, this isn't always true. You can have one engine that just has a longer power band, creating a huge area under the curve. Best example I can think of right now is the GM LT5 Vs. LS6.

blackhawk
11-16-2007, 07:48 AM
I'm sure you already know this, but for anyone that doesn't:
HP = (Torque x RPM) / 5252
That's why the HP and Torque curve lines always cross at 5252... It also explains what HP actually is.
While I generally agree, this isn't always true. You can have one engine that just has a longer power band, creating a huge area under the curve. Best example I can think of right now is the GM LT5 Vs. LS6.

Yes I know the formulas. I used them to get my numbers in my example. :D

I think a lot of people don't realize that hp and torque go hand-in-hand. If two motors make identical hp at 3000 rpm, they also make identical torque numbers at 3000 rpm.

And I will agree it's not ALWAYS true that the lower rpm motor makes more low-end torque, but in most cases it is. In this example where there is a 1000 rpm operating rpm difference the 383 has almost 100 lbs less torque at peak rpm, so I am willing to bet the 502 has more torque from 2000-4000 rpm. Any takers? :D

DonziFreak
11-16-2007, 08:15 AM
this is gettin intresting :popcorn:

VetteLT193
11-16-2007, 08:40 AM
...
And I will agree it's not ALWAYS true that the lower rpm motor makes more low-end torque, but in most cases it is. In this example where there is a 1000 rpm operating rpm difference the 383 has almost 100 lbs less torque at peak rpm, so I am willing to bet the 502 has more torque from 2000-4000 rpm. Any takers? :D

I totally agree in this case :) E

even if the 383 has a pretty flat torque curve (which, IMO, is one of the hardest things to come out with when building an engine), I doubt it stands any chance of having more torque down low than a 502

BigGrizzly
11-16-2007, 05:15 PM
Black Hawk Sorry you are wrong both both parts There is no magic 5250 torque when torque is always higher then HP under that number. It is not true that two engines with the same horse power will have the same torque at at 3,000. It is true that horse power and torque go hand and hand. So to turn your theory around: two motors make identical torque 700lbs at 3900 then the horse power should be identical The fact is we have built several with this number. And the operating range is quite different. I have been doing this for over 40 years. what I will say is theory is good but HONEST testing is TRUTH. I have put that theory to bed a number of times. You are welcome to your opinion. And I will take mine to the bank. No matter what article or rag you quote, I will believe experience and countless hours on the dyno.
Vette where did any one compare a 502 with the 383. I gave number for an example not a comparison.

blackhawk
11-19-2007, 08:12 PM
Black Hawk Sorry you are wrong both both parts There is no magic 5250 torque when torque is always higher then HP under that number. It is not true that two engines with the same horse power will have the same torque at at 3,000. It is true that horse power and torque go hand and hand. So to turn your theory around: two motors make identical torque 700lbs at 3900 then the horse power should be identical The fact is we have built several with this number. And the operating range is quite different. I have been doing this for over 40 years. what I will say is theory is good but HONEST testing is TRUTH. I have put that theory to bed a number of times. You are welcome to your opinion. And I will take mine to the bank. No matter what article or rag you quote, I will believe experience and countless hours on the dyno.
Vette where did any one compare a 502 with the 383. I gave number for an example not a comparison.

You're kidding right? I am not quoting anything and these are not "magical" numbers. Nor are they theories. These are mathematical formulas. I'm not doubting your motor building experience but that doesn't change mathematical facts.

Fact: Hp and torque ALWAYS cross at 5252 rpm. (meaning they are the same)

Fact: Under 5252 rpm torque is ALWAYS higher than hp. Over 5252 rpm hp is ALWAYS higher than torque.

Fact: Two motors that both make 700.00 lbs of torque at 3900 rpm will BOTH make 519.80 hp at 3900 rpm. They HAVE to. It is mathematically impossible for them to make different hp at 3900 rpm.

Fact: The opposite applies. Two motors that both make 519.80 hp at 3900 rpm will BOTH make 700lbs of torque at 3900 rpm.

BTW Pismo posted about comparing it to a big-block.

Again, not questioning your hands-on motor building but these are mathematical FACTS, period.

DonziFreak
11-19-2007, 09:26 PM
hey, not to get on anyones bad-side here, but I did find this on the web....


To calculate motor full-load torque, apply this formula:

T = HP x 5252 / rpm

T = torque (in lb-ft)
HP = horsepower
5252 = constant
rpm = revolutions per minute

blackhawk
11-20-2007, 08:45 AM
hey, not to get on anyones bad-side here, but I did find this on the web....
To calculate motor full-load torque, apply this formula:
T = HP x 5252 / rpm
T = torque (in lb-ft)
HP = horsepower
5252 = constant
rpm = revolutions per minute

Yep, and HP = rpm x torque/5252

5252 is the constant because hp and torque are ALWAYS the same at 5252 rpm.

BigGrizzly
11-20-2007, 08:47 AM
Believe what you want. All i can say again I am shure I have built more engines than you have. I don't buy I build. Remember even Eienstines theory of realitivity has been proven incorrect. Also temember Voltage in the receptical used to be said to be 110vac, then 115vac, now it is 120vac. Well it had never been 110 ,or 115, but due to line drop and temperatures it has always been between 118 and 123vac. that formula is general. and has been proven wrong more then once. just like the desk top dynos. generally you are correct but not always as you stated. Personally I feel you are entitled to your opinion. You can keep discussing this if you want. Its going to be in the mid 70's today and there is still water in the lake, I am going for a ride in my 690+ hp Criterion That gets the same fuel economy as a stock 502. Have a nice day, I am.

blackhawk
11-20-2007, 08:52 AM
Believe what you want. All i can say again I am shure I have built more engines than you have. I don't buy I build. Remember even Eienstines theory of realitivity has been proven incorrect. Also temember Voltage in the receptical used to be said to be 110vac, then 115vac, now it is 120vac. Well it had never been 110 ,or 115, but due to line drop and temperatures it has always been between 118 and 123vac. that formula is general. and has been proven wrong more then once. just like the desk top dynos. generally you are correct but not always as you stated. Personally I feel you are entitled to your opinion. You can keep discussing this if you want. Its going to be in the mid 70's today and there is still water in the lake, I am going for a ride in my 690+ hp Criterion That gets the same fuel economy as a stock 502. Have a nice day, I am.


Sorry BG these are not theories or opinions, these are facts. Being a motor builder I am shocked you don't know these formulas.

cutwater
11-20-2007, 09:10 AM
An important thing to remember that often confuses people is that

Torque "being equal" to HP at 5252 rpm MEANS NOTHING!

because torque and horsepower can NEVER equal each other, they are different units of measurement. 5252 is not a magic number, it simply falls out of the equation by nature of the unit definition. For instance, if you were measuring engine power in kW and torque in Newton-meters, the place where power and torque are "equal" is at 9549 RPM. "Equal" is a BAD way to think about it.

5252 is NOT a magical number, but yes any two different engines (NEGLECTING LOSSES) which have 500 ft-lbs of torque at 5252rpm WILL both have 500 hp at 5252 rpm. Not debatable.

BigGrizzly
11-20-2007, 09:25 AM
I know the formulas very well as well many others. I just don't use them. Like I said Theories are good but honest testing is truth. I was told by several engine Supermen that I couldn't closed cooling a blown 700Hp 502 and have it live. Well that was many years ago and now I have several much larger ones out there. Now everybody is getting into the act. I was told 170 degrees was to hot for a blower marine engine, that was 800 hours ago on mine. Wipple still says NO, but I have done is successfully many times. In the 1970's it was said by every major manufacturer, that Catalytic converters would kill fuel economy and horse power in the general production cars. Well guess what fuel economy has never been so good nor horse power been so high, they were also formulas then too. in 1975 they put restrictor plates on the Daytona 200 motorcycle races bikes, bikes were found to go faster. The volumetric efficiency formulas have been around for years but people keep putting 750 cfm. carbs on 350cids and think they are better. Many forums about this subject exist. So who is right ? All the formulas or all the people who do not follow them. Or maybe, just maybe only some of formulas are not always correct. I will also bet money you don't follow all the formulas either, which is it? you follow ALL the formulas and I will be waiting at the finish for you.

blackhawk
11-20-2007, 09:27 AM
5252 is NOT a magical number, but yes any two different engines (NEGLECTING LOSSES) which have 500 ft-lbs of torque at 5252rpm WILL both have 500 hp at 5252 rpm. Not debatable.

Thank you, someone gets it. My point was simply if two motors make the same hp at a certain rpm, then they also make the same amount of torque at that same rpm.

cutwater
11-20-2007, 09:44 AM
Hey Grizz, I agree with you and I disagree with you. What you are saying is that you can't strictly apply these formulas and get the perfect engine. It takes real world tuning. This comes from the fact that these formulas don't accurately model the real world. I completely agree with you, but.....

These formulas NECESSARILY hold true, and I can tell you that we ALL believe them in a roundabout way. Because when you put an engine on the Dyno, you do not measure horsepower, you measure radial force (read torque) and multiply it by RPMs/5252 to CALCULATE the horsepower. Therefore Dynos do not directly measure horsepower (read work), they instead measure torque and then rely on these formulas. The formulas are what we base the fundamental definition of horsepower on. These basic formulas CAN'T be wrong, but you are right that they don't completely define the art of engine building.

RedDog
11-20-2007, 09:57 AM
Hey Grizz, I agree with you and I disagree with you. What you are saying is that you can't strictly apply these formulas and get the perfect engine. It takes real world tuning. This comes from the fact that these formulas don't accurately model the real world. I completely agree with you, but.....

These formulas NECESSARILY hold true, and I can tell you that we ALL believe them in a roundabout way. Because when you put an engine on the Dyno, you do not measure horsepower, you measure radial force (read torque) and multiply it by RPMs/5252 to CALCULATE the horsepower. Therefore Dynos do not directly measure horsepower (read work), they instead measure torque and then rely on these formulas. The formulas are what we base the fundamental definition of horsepower on. These basic formulas CAN'T be wrong, but you are right that they don't completely define the art of engine building.

Jeez - even the electrical engineer understands the relationship between work and force :wink:

cutwater
11-20-2007, 10:02 AM
Jeez - even the electrical engineer understands the relationship between work and force :wink:

Electrical engineering? Oh crap! So THAT'S what I'm supposed to be doing right now! :propeller: I'm going to put down the popcorn and get back to work....

BigGrizzly
11-20-2007, 10:10 AM
Cutwater that is my point completely define engine building. This started out, if Merc could build a 383 with enough torque, I said they could. Yes I use formulas but don't rely on them completely. If people did advancements would never happen. Quite frankly a Dyno is only a relative tool and is just for comparison. Dyno vary from shop to shop. we have a mule that is never modified, we use for corrections and updates. the real test is application. BTW my wife forces me to work. Anyway I am going for a boat ride.

VetteLT193
11-20-2007, 10:17 AM
I know the formulas very well as well many others. I just don't use them. Like I said Theories are good but honest testing is truth. I was told by several engine Supermen that I couldn't closed cooling a blown 700Hp 502 and have it live. Well that was many years ago and now I have several much larger ones out there. Now everybody is getting into the act. I was told 170 degrees was to hot for a blower marine engine, that was 800 hours ago on mine. Wipple still says NO, but I have done is successfully many times. In the 1970's it was said by every major manufacturer, that Catalytic converters would kill fuel economy and horse power in the general production cars. Well guess what fuel economy has never been so good nor horse power been so high, they were also formulas then too. in 1975 they put restrictor plates on the Daytona 200 motorcycle races bikes, bikes were found to go faster. The volumetric efficiency formulas have been around for years but people keep putting 750 cfm. carbs on 350cids and think they are better. Many forums about this subject exist. So who is right ? All the formulas or all the people who do not follow them. Or maybe, just maybe only some of formulas are not always correct. I will also bet money you don't follow all the formulas either, which is it? you follow ALL the formulas and I will be waiting at the finish for you.

Grizz... HP is not a theory, it's a calculation. We can't measure HP, only torque, so we come up with HP based on torque. All the other formulas/calculations you list have many other outside variables that weigh in. Those calculations are generally used to assist in developing an engine and the people that use them know they aren't perfect.

With HP, it is what it is... every Dyno uses the same calculation because HP is a made up quantification that helps to compare one engine to the next. Because it was made up, the formula is never going to change... Saying that it is or even could change is like saying the length of an inch could change, so you don't use a tape measure.

Also, comparing the operating range of an engine (or other random items) has nothing to do with HP or torque at a particular RPM, it has to do with the entire Torque and HP curves, and the area beneath them.

And I was responding to blackhawk regarding the 383/502 thing. Just as a devil's advocate more than anything else... I was going to post a dyno chart of a Chevy LT4... It has a flat torque curve + plenty of high revving HP, which would support your opinion about the low end torque

BigGrizzly
11-21-2007, 08:07 AM
Actually horse power measurement came first it was derived from a horse lifting a load on a 25 foot tall saw horse through a pulley system with a pulley on the top of the saw horse then the one on the ground to the horse halter. This was done in the 1600s. Like all measurements. The foot came from the king at the time and so on. I have explored all the theories. My grand dad made parts for Offenhouser and designed many items used on ships etc. The statement was saying it doesn't work all the time-which is true. Many people make statements and state theories without knowing the total out come. You caused some people to spend time on the internet, me included, looking for a stainless J rail because you said They make it and your brother had one on his 22! Later yo commented he didn't. BTW after many hours of research and talking to manufactures, No one has ever made one and won't because it is almost impossible to bend to shape without distorting even with heat. Playing devils advocate seems ok for YOU but not for ME. Most people on the board know me, my equipment and what I am capable of. This thread is getting out of hand and I' not going to pursue it any longer.

DonziFreak
11-21-2007, 08:15 AM
I gotta side with Griz on this one, this forum was suppose to be about the 383, instead, everyone is arguing and taking shots at each other.....

By the way Grizz, i started thinking about it, and what you're saying is true, torque won't necessarily be the same, because factors like port designs come into play.....I was thinking about it while i was building a dolly for our race boat, haha....

gcarter
11-21-2007, 08:38 AM
Guys, this magic # is a constant, nothing more.
I can think of hundreds (maybe thousands) of engines whose HP and torque never approaches 5200 RPM.
And what about all those hydraulic motors and pumps I used to calculate that didn't generate an ounce of power in and of itself?
Obviously you can generate a kajillion lb/ft of torque and nothing moves at all.
I think several of you are barking up the wrong tree.

BUIZILLA
11-21-2007, 08:57 AM
actually, everybody's wrong... :pimp:

cutwater
11-21-2007, 09:31 AM
Okay, I guess I'm about done with this thread too. It is starting to get a little out of hand. The equation that BHawk posted is not fact, nor is it theory, it is the very definition of horsepower (a human convention). We only use equations to describe the world around us. In this case, even if you want to say the equation is wrong or even limited, it doesn't matter because it's how we understand engine power in the first place.


And what about all those hydraulic motors and pumps I used to calculate that didn't generate an ounce of power in and of itself?
Obviously you can generate a kajillion lb/ft of torque and nothing moves at all.
I think several of you are barking up the wrong tree.

George, you are correct, and just proved the equations true... Work = Force x Distance... Therefore, you applied force with the motor, but it wasn't enough force to move the object (distance=0), therefore NO WORK WAS DONE (therefore no power). Even if you generated 20000 lbs of force, Work = 20000 x 0 = 0 !! How is it 'barking up the wrong tree' to say that the definition of engine power is correct?


By the way Grizz, i started thinking about it, and what you're saying is true, torque won't necessarily be the same, because factors like port designs come into play.....

True, but you have to remember, we are only talking about any ONE rpm value. Two engines that have the same torque at ONE rpm value have therefore the same horsepower at that ONE rpm value. This true statement, however, says nothing about ANY OTHER rpm value, the engine performances could be and probably will be completely different.


Quite frankly a Dyno is only a relative tool and is just for comparison. Dyno vary from shop to shop. we have a mule that is never modified, we use for corrections and updates. the real test is application. BTW my wife forces me to work. Anyway I am going for a boat ride.

Again, this has nothing to do with a fallacy in the horsepower formula, it is a calibration error (read human error) that is the fault of the engine shop. By the way, a boat ride sounds good right about now... :wink:

Enough stepping on toes for one day.... :yes: Done with this thread & back to work :eek: !
John

Pismo
11-21-2007, 06:12 PM
I think this new Merc 383 400hp in a Bravo I (or even an Alpha) package would be great in an 18 Classic........

DonziFreak
11-21-2007, 07:29 PM
I think this new Merc 383 400hp in a Bravo I (or even an Alpha) package would be great in an 18 Classic........

thanks for gettin us back on track!!!!

a 383 with a bravo would be cool.....now i just gotta find the 8k i don't have...i know i left it around here somewhere.....:doh: :)

Skeleton Crew
11-22-2007, 09:21 AM
I think this new Merc 383 400hp in a Bravo I (or even an Alpha) package would be great in an 18 Classic........

Would the Alpha hold up to that much power and be reliable?

Last Tango
11-23-2007, 08:56 AM
Now that this thread is THANKFULLY back on track,...

I was wondering about my Bravo One drive being enough for this motor combination, Since I'm running a 350 MAG MPI with a 1:65 Ratio Bravo One drive on an '06 22ZX I was wondering about having to upgrade my Bravo One since even the 22 Classic with a 496 MAG HO gets the heftier Bravo One X. That is a lighter boat than mine and easier to push. The factory spec HP rating limit on a stock Bravo One drive is 400hp, so I guess I should be okay. I really like this new motor since it dramatically upgrades performance without adding a supercharger.:yes:

Skeleton Crew
11-23-2007, 09:22 AM
Yeah/no :) :)
Setup properly, it "should" survive... Been done by several here on the board. The boats lightness helps it survive. Pull the top off, have the HD gearset installed, keep a close eye on the gear oil...

My concern is not so much the power, but the high RPM to achieve the power. The upside would be less torque to deal with. I'm also not certain that just jumping up to a Bravo drive is going to solve the issue of high RPM.

Last Tango
11-23-2007, 09:35 AM
Well, I would guess that Mercury will do their homework and offer an outdrive that will take all this. They already have the technology.
Interesting that these engines are REmanufactured Scorpion motors. So what happened to the originals that they now have this surplus of rebuilt engines to offer?

Cuda
11-23-2007, 04:32 PM
I think an 18 with this engine and an Alpha would be a screamer. I'm betting an Alpha will hold up fine, if you run a drive shower, and keep good drive oil in it. It should be faster than the 383/Bravo.

Pismo
11-23-2007, 07:45 PM
I think an 18 with this engine and an Alpha would be a screamer. I'm betting an Alpha will hold up fine, if you run a drive shower, and keep good drive oil in it. It should be faster than the 383/Bravo.


I agree, sounds perfect....Need a hot prop too.

DonziFreak
11-23-2007, 09:31 PM
i'm not a big fan of the alpha's.......i've seen to many things go wrong with them in my time (not saying they are bad drives, just that i dont perfer them) and i would like to see this offered in some bravo package.....besides, i've been wanting to swap the volvo 270 for a bravo for some time......i just can't afford it at the moment, oh well! guess i gotta make budget cuts.....hmm, first thing to go.....i know! my brothers damn motorcycle! (he can't ride worth of crap anyways!) :biggrin:

BigGrizzly
11-24-2007, 09:26 AM
D freak, you should try one of my Volvo props you will be surprised at the difference it makes.

DonziFreak
11-24-2007, 02:43 PM
D freak, you should try one of my Volvo props you will be surprised at the difference it makes.


thats something i might consider.....could you maybe send me some info about them? like what the diffrences and all are?

you could private message me here or email me at TheGoodGuy30@aol.com

blackhawk
11-27-2007, 09:27 PM
I didn't mean to help get the thread off topic but I was having a hard time getting my point accross. I admit I used wrong words like "fact" and "equal". All I was trying to say is there is a formula and it has a constant which means the formula will give you consistant answers when converting torque to hp. :D

Anyway, back to the motor. It does sound like a great motor and spinning 6000 rpm would sound sweeeeeet! But I don't know how well the drive would hold up on long WFO runs?

harbormaster
12-27-2007, 10:38 PM
I do not know where some of you experts get your info...
The Bravo would hold up just fine to 6k runs.
We have customers that run close to that with big blocks with more torque.

As for the origin of these engines, they start with 6.2 blocks that are out of Spec. Instead of scrapping the engines, Merc Remanufacturing gets them from Mercruiser, bores them to 383's and adds nice components....

Mercury has different entities (Merc, Merc reman, Merc racing, etc.) that operate almost independently of each other...

I have seen this engine and it looks badass.

Last Tango
12-28-2007, 09:11 AM
Is it possible they will have one of these on display at the Miami Boat Show? If so, where should I look? I'm already getting a wet spot in my jeans thinking about adding this to my 22ZX. Oh, yeah, Baby!

roadtrip se
12-28-2007, 11:03 AM
After a season of running, and riding more than running, in this beast, I can say that it is an absolute riot.

Power curve peaks at 5200 and takes no time at all to get there. I have never run a smoother engine in a boat. Not a rough edge to be found from idle all the way to the top.

It is butt heavy and lands butt first when up in the air. The 18 can spend a lot of time flying, so I would be dubious about doing it with an alpha and having it live for very long with this power. We will install headers, sooner or later, to take some of the weight out, but in the mean time, we will just live with this mile-a-minute, laugh riot.

We could be talking apples and oranges here between the 377 and 383, but the real world experience with this HP package in our little boat makes it a winner.