355ci vs 383ci

[mkast]

Re: 355ci vs 383ci

After researching the pro's and con's, I went to a used (20hrs)454, no problems, no sweat, no looking back.

 

[SuperNova]

Re: 355ci vs 383ci

If a little bigger is good, A lot biggerer has to be betterer. I like your thinking!!
--
Stan

 

[John_S]

Re: 355ci vs 383ci

Stan,

The stock vortecs have 170cc intake runners, so with a little work, should make 175. Thats why I thought they would be good enough, and would save some considerable dollars on the build.

http://www.sallee-chevrolet.com/Fast_Burn_Cylinder_Heads.html

 

[SuperNova]

Re: 355ci vs 383ci

The stock Vortech are swirl and tumble type castings (VORTECH=VORTEX). They are NOT good for flow. They are good for efficiency though. But to make power you need both. And it is very difficult to port them and very easy to make them worse. Flow bench definitely required as is extensive porting experience. Good heads are only about a grand assembled. Just dump the screw in studs that come with the heads and get a set of B&B's. Trust me on that one-learned the hard way. For an engine to run steady at 4500-5000 for anytime at all, you need a stable and strong valvetrain.
--
Stan

 

[Bonus]

Re: 355ci vs 383ci

In theory a 383ci "stroker" will have more low end torque, than a 350/355ci. If you go with vortec heads, then strict adhearance to typical compression ratios is less important as pre-detination is not a common issue with these heads. The "quench" or distance from the piston to the deck is the key. If your machine shop builds a mild 383, with "standard" vortec heads, and you put in a mild marine cam and good intake and exhaust you will have all the HP you can use. (and lots of torque) This is all detailed in Dennis Moores book.

Bob

 

[Bondo]

Re: 355ci vs 383ci

Ayuh,........ I Totally Agree with Bonus Bob,.........And by proxy Dennis Moore.......

And I also Think Stan is Full of It.......

Lastly, there are clearance notches that must be machined into the oil pan rail area that leave only a few thousanths of an inch of metal between the cooling jacket and the inside of your engine(where the oil is). On a raw water cooled engine, it rusts thru rather quickly. I'm sure you can imagine what happens then.

With 5.7 rods it's less than a 1/4" in a pan rail that's over 1/2",......
And it's done by Hand with a Die-grinder......
The Waterjacket is Well Above the pan rail......

Vortecs Flow just Fine..........Dead Stock.......
Anymore than the 170cfm of so,+ Torque down Low goes Out the Window......
More Vortecs are Destroyed with a Die-grinder than are Improved.....

A SBC Chokes in a Boat because of the Exhaust we run................

All that Porting & Polishing will build a Dog in a run of the mill Boat.........
Unless of course you'd like to Dump a Couple of Grand for True Headers..........

 

[180shabah]

Re: 355ci vs 383ci

Thank you Bond-o for setting the record straight. This guy is only looking for 300-350hp (pretty mild) from his small block. This does not require aftermarket heads, a wild cam, exotic valve train etc...

 

[Ryan00TJ]

Re: 355ci vs 383ci

I recently went thru this over the winter. 383 vs 355? My 21' Challenger is very light 2600lbs and did not need the added torque as much as a heavier boat. I am also overpowering the Alpha 1 even though it has HD upper gears. I went the 355 route as I allready had the pistons and rods in the shop.

Eagle 4340 3.480" crank, forged I beams and TRW L2304 forged pistons, rotating assembly balanced very well. 1980-85 4 bolt block align honed, decked .020", bored .030" Melling M55A HO oil pump, Moroso 7qt oil pan w windge tray.

Edelbrock Performer RPM intake
AFR 190cc aluminum heads 74cc 10.0-1 SCR, .039 quench, 2.02I, 1.60E, Flow 261cfm @ .500 with strong midlift flow numbers
Morel Retrofit Roller lifters
224/230 .537/.511 112LSA 110ICL roller cam
Crane 1.6 roller rockers on I, Lunati 1.52 rollers on E
Holley 4150 750CFM carb
Smith Bros .083" wall 1 piece pushrods
Glenwood Marine HP aluminum manifolds w FastGlass 4" stainless smooth long risers that are 16" long. Almost a dry system as water hits the exhaust 3" before it leaves the tips. No Reversion

Engine Made 426hp @ 431tq on the dyno with dyno headers. With the marine exhaust I figure it will make around 400hp. Runs like a dream and very powerful and torquey. Idles 775-800rpm N and 675-700rpm in gear idle. Pulls hard to 5500rpms.

A 350 block needs clearanced as mentioned near the pan rail for the added 3.750" stroke. Does not effect the integrity of the block or cylinder wall in the least. A 6" rod is better than a stock 5.7" rod as the piston stays longer at TDC and resists side loading the cylinder wall. Use the longest rod possible is always the best approach. 383 spec pistons will be needed.
Have the block bored, align honed, decked and clearanced.

As to a 383 running hotter than a 355 I do not buy into this. I've never seen it and i've been around both types.

To do a 383 right your going to be going aways over $3K.

Here are a few pics of the 355

 

[Cptkid570]

Re: 355ci vs 383ci

Norm,
Are you that unsatisfied with the power you've been getting out of your 350, 2 barrel?

Have you checked with Raul at Rapidomarine.com to see how much he'd charge you for the long block + shipping? I'm guessing around $1700 including shipping. And could stick a 4 barrel exhaust manifold in there for any extra $75 - $100.

Are you capable of doing the work yourself? Do you have a way/place to hoist out the existing engine and put another one back in? If so, why don't you just get the 5.7 from Rapido Marine, take all of your parts off the old engine, stick them on the new engine, and upgrade to a 4 barrel?

 

[SuperNova]

Re: 355ci vs 383ci

That's why we are all individuals. If we all thought the same way there would be no progress whatsoever. And I may be full of it Bond-o, but I did stay at a Holiday Inn last night. OH, and the vortech heads don't FLOW 170 cfm , the RUNNERS measure 170 CC. It's a size measured by how much liquid they'll hold and the procedure involves using a burette. But I'm sure that's in a book somewhere, maybe the chapter you skipped. Go check, I'll wait. And by the way, in case you've never used an oil TEMP gauge, 383's do run higher oil temps than 355's. Just a little more REAL WORLD experience for you. By the way Bondo if you never broke through into the water jacket (which I assure you is right at the pan rail) you don't really know how much material is there. I do because I have broken through. Love ya babe.

Nice build by the way Ryan. I did almost the exact same build for my '86 20' Wellcraft that originally had a 4.3 v6. Except I didn't pony up for the roller cam setup. That thing ran good. I had 1.5's in the alpha I and ran a 26" pitch prop. There was NO plane time, the thing leaped out of the water when you hit it. When I would run at 3/4 throttle and punch it, it accelerated like a hot rod, shoved you back in the seat and held you there. I have no idea how fast it really went (pre-gps for me) but I was really happy with it. Oh, yeah, if your rocker studs are 3/8" ,make sure they are top quality, the ones that came in my AFR's broke after running at anything over 4500 for more than a couple of minutes. I had to go with B&B's, they have a nice radius at the hex. If the studs are 7/16" then you probably won't have a problem.

--
Stan

 

[hudman]

Re: 355ci vs 383ci

I was facing the same problem last year, I opted for a 383 from mercruiser, its vortec, fuel injected, comes from their reman division, its awesome! after getting the installation bugs worked out, it has been trouble free! 325 hp at the prop, and turns a big bravo 2 about 4950 rpm, which translates to 42 mph on a 27 ft cruiser. fuel useage is lot less than the old 350 carb motor. check it out!!

 

[Bondo]

Re: 355ci vs 383ci

No Disrespect intented Stan,...... Sorry Man.....
And your Right,..... I mis-spoke about the CCs, Vs. CFMs......

In the Vortec Head's case,...... They're the Cream of the Crop for building Torque, Down Low........
That I'll argue All Day Long...........

As for the 383 Debate,.....
It's just that Most of the concerns you list are Sometimes Possible,.....
But there are Millions of Sucessful 383s out there,......
Mercruiser themselves have been selling the 'ell out of them.......

The Long Rods, Vs. Short Rods can Also be argued All Day Long,......
Over at the Hotroddersdotcom forums,...... It Usually Is,......
And We haven't even gotten into the 5.565 rods.......

Again,...... No Harm, No Foul,... No Disrespect Intended,....
I respect you for the Mechanic that you Are........

 

[Ryan00TJ]

Re: 355ci vs 383ci

SuperNova, 7/16" studs come standard on all AFR SBC heads. I've yet to have a problem. As to the 383 oil temp issue i'm not doubting it, but have never heard it mentioned. I have a few buddies that upgraded from 350's to 383's and 406's and they never mentioned them running hotter oil temp. Maybe due to the use of oil coolers to keep the temp 190-200*.

 

[tie_one_on]

Re: 355ci vs 383ci

Posted by Bondo......

And I also Think Stan is Full of It.......


WOW!!!!!! If that isn't disrespect..... what would it look like?

 

[NormRinker]

Re: 355ci vs 383ci

The Bravo III and large gas tank indicates a large, heavy boat. If so, go with the 383 for the extra torque, lower in the rpm range.

It is a 1998 Rinker Captiva 232 cuddy cabin boat which is 23'6" long tipping the scale at 4,215 pounds dry per the manufacturer's specification sheet. I would think it is about a 24' boat and well over 5,000 pounds wet and loaded with 75 gallons of fuel, 10 water gallons, and several people.

A picture:

 

[NormRinker]

Re: 355ci vs 383ci

If you're using a bravo III you're good for about 400hp.

Do you know the ratio? If you post the model/serial numbers Don can tell you exactly what you have.

If you want more performance you could opt for a 454 or 502. In fact I am going to either buildup a 502 or find one in a year or so to replace my 454.

I have a 1.81 ratio Bravo III.

Your's is probably 2.00:1 or 2.20:1 model if it's behind a small block.

depending on the year of the engine, You also probably have a rev limiter too....Is it fuel injected? The model /serial numbers will also determine what the max rpm is.

It is a 1998 model, and the engine serial number is 0L076764. I am not sure of my Bravo III gear ratio, but I can probably find that information in one of my MerCruiser manuals that I bought from Ebay.

I don't know if there is a rev limiter on my engine or not. Can this information be found? It is a 2 barrel carburetor engine with Thunderbolt ignition. I have never went that far on the tachometer to find out.

A big block swap would be cool, but the cost may be higher. Everything would be different so I would need a lot more parts. I can build a healthy small block for the same performance with less weight, or to buy a new exact replacement long block and leave it alone as is.

 

[NormRinker]

Re: 355ci vs 383ci

While I agree that Abunch of HP can be built with a 350,.....
But,........You'll build More Usable HP with a 383......

That's a good point. "Usable" HP.

And,.... I've never heard of a 383 running Higher oil or water temps than a 350 worked at the Same rate..........

Me either until this race engines shop owner told me. I didn't question his credibility there because he has been doing it successfully for 35 years. I am significantly younger than that 35 years he is into it. He built good racing engines for my significant other's now deceased father who raced a lot quarter mile at a time. He also build oval racing engines. I can ask for his further explanation on it whenever I am there again which I am sure he will provide me with. That would be an interesting one.

And,..... While a SBC can turn Well over 5000rpms,......
Dependability goes downhill Quickly, for not only the motor, but your Drive as well when you try running the High side of 5000rpms......

How true. I will probably not want to go to the high side of 5k anyway. I think around 5200? or less would be good enough for me.

To build serious HP,+ Torque,..... There's No replacement for Displacement.......

Usually true, but not always. How about the Formula cars with their little liter engines churning out some very serious numbers? Cubic inches are always good for naturally aspirated applications, but smaller can be as good some times.

I'm Still putting together a 383,.....With a set of Vortec heads at a tight quench,... a Cam in the 214 to 218 range,....Compression ratio around 9.5 to 10:1....With a 4bbl. carb,.......
I'm expecting near or over 300hp.......At Less than 5000rpms......

That's nice you're building a 383. It should make for a good motor. What block, rotating kit, etc. did you go with? I have been reading about the possible locations on water jackets around the oil pan rails area. I should find an old block to hack up and see for myself. Anyway, I've been reading about "Quench". How do you know what Quench it is?

As noted,..... The Cam's LSA has to be kept between 109*,+ 112* to prevent Reversion......

Noted and filed away.

 

[NormRinker]

Re: 355ci vs 383ci

I was facing the same problem last year, I opted for a 383 from mercruiser, its vortec, fuel injected, comes from their reman division, its awesome! after getting the installation bugs worked out, it has been trouble free! 325 hp at the prop, and turns a big bravo 2 about 4950 rpm, which translates to 42 mph on a 27 ft cruiser. fuel useage is lot less than the old 350 carb motor. check it out!!

I saw a Merc Reman 383 on Ebay for $6,2k all complete ready to drop in and run. It looked awesome, but that $6,2k is some serious dough for me. It is an option, but a very costly one at that. Will the fuel savings pay for itself over the life time of my boat with me? I am not even sure how long I will keep this boat. Who knows I will want a different boat some day? I think your motor can probably push my boat past 50mph.

 

[HT32BSX115]

Re: 355ci vs 383ci

Maybe I missed something (I went back and read this thread again) What kind of a boat are you putting this engine in?

It's a Bravo III too you said?

I saw a 383 from Merc Reman on Ebay for $6,2k all complete ready to drop in and run. It looked awesome, but that $6,2k is some serious dough for me. It is an option, but a very costly one at that. Will the fuel savings pay for itself over the life time of my boat with me? I am not even sure how long I will keep this boat. Who knows I will want a different boat some day? I think your motor can probably push my boat past 50mph.

 

[NormRinker]

Re: 355ci vs 383ci

Norm,
Are you that unsatisfied with the power you've been getting out of your 350, 2 barrel?

Have you checked with Raul at Rapidomarine.com to see how much he'd charge you for the long block + shipping? I'm guessing around $1700 including shipping. And could stick a 4 barrel exhaust manifold in there for any extra $75 - $100.

Are you capable of doing the work yourself? Do you have a way/place to hoist out the existing engine and put another one back in? If so, why don't you just get the 5.7 from Rapido Marine, take all of your parts off the old engine, stick them on the new engine, and upgrade to a 4 barrel?

It is not that I was "that unsatisfied" with the power this engine had. I just want some more since it blew both head gaskets. A power upgrade to go along on top of the fix to my seized engine would help make me feel better about it all if you know what I mean.

For the $1700 you are guessing it will cost to buy a rebuilt long block from Rapidomarine.com, I would rather spend $1300 at a local Chevrolet dealer for a brand new short block, of the correct year. Then to cam it maybe with a mild cam and put the top end together on it using correct marine gasket set. It does have the correct brass freeze plugs, and I can always file fit the piston rings to MerCruiser's specifications if necessary. It is a brand new 4 bolt mains block with 1 piece rear seal, powered metal rods, and cast pistons with the correct 4 valve reliefs like stockers. Maybe not a 010 content block though as how the original one is.

Yes, I am capable of doing the work myself. In fact, as I type this, my motor is already sitting on an engine stand in the garage disassembled down to the short block. I am going to finish tearing it down, before I start to make the decisions that I need to make. GM Goodwrench long block, or short block and assemble the rest myself, or 355/383 by either myself or a machine shop, or crate. I'm probably just thinking too hard here.