Looking for 400hp on 383's
 

Hi everyone, my engine builder is almost done with the 383's and I am wondering how many hp/torque should I expect from them, this is the set up :

Eagle rotating assembly
Steel crankshaft
Performer cylinder heads 70 cc
Hyperteuntic dome pistons
9:1 cr
PRW alum rockers 1.5 ratio
Performer air gap intake
Edelbrock 1410 750 cmf carb
Comp cam 12-318-4
222/226 at .50 lift
.464/.464 valve lift
110 LSA
Stainless marine "hi torque" exhaust w custom risers

Hopefully this is enough info for the estimate

I would like to get only constructive criticism pls , thanks

I couldnt give you a number but to me with 383's, your cam specs look tame. I bought the engines for my boat and had my guy go through them. He said we were leaving HP on the table with the cams that were in them but they would make good torque. In the end we left them in there. They're 355s and make over 400lbs T. With the twins the boat has all kinds of balls down low but wont rev past 5000. In retrospect I wish I had sacrificed some bottom end and let them rev and make some HP. Although it planes like a ski boat for all the work involved the boat isnt all that much faster top end then it was with the stock 270hp 350 mags.

Agree with you 100% ,cam could have been more aggressive ,had a talk with my guy about it , and since I am not going to be revving that high either ,we decided to go this way, a nice bottom end is not bad .

Thanks for your comments.

Ps: will be running mirages 25p

Anybody else? Where are the experts?

I know it is just a couple of sbc's but I really want to know your sincere opinion.

Thank you all in advance

I'd say about 360-385 at the crank - on a dry dyno through headers and no accessories. (or more appropriately the dynos accessories)

300 or so to the props with all accessories turning and with that exhaust.

Should idle well and last a long time. Id say you left about 40 HP on the table with your choice of sticks.



Uncle Dave

We used about the same bottom end. The top end we used world sportsman heads 202 vavles 200 cc runners Bullet cam grind #CHS288/296-10HR part #501000 spec 223/231 @.050 lift .530/.548 110 separation same intake edelbrock 750 cfm carb 425hp @ 5700 rpm stainless Marine exhaust with long risers. I dont remember the Tq. Hope this helps !!!!

Buddy, thats a sinifigantly lighter boat than mine with 383's, you'll have all kinds of bottom end. Put the camshaft to them and pull the big number.....I wish I did.

A cam change is in the works for me but it wont be this year.

I agree with this 100%, I think you'll be disappointed with that cam selection with the rest of the components you've assembled.

Do it now, or regret it later.

As for your question, the expert is right here. He can get you what you are looking out without making many sacrifices.
http://www.marinekineticsonline.com/

fixx
 

ummm,,your going to have allot more compression then you think! im using a .046 gasket,zero deck,,same heads as your usnig but a 355 and im at 10.2 to 1 with srp flat top pistons..thank god your using alunimum heads,shave 1 point their..

you will probably see 400 ponys and it will be all over with @ around 4500 rpm..i would go witrh the zz4 cam..

How would the lt4 hot cam compare to the zz4 cam in this application? I'm considering making a 383 out of my 350 and have a lot of the same questions as the OP.

My biggest concern if I went bigger with cam is reversion. I'm forced to run silent choice with short risers. I know cubic inches will mellow a cam but how far can it be stretched only adding 33 CID?

Thank you all of you for your replies, I will consider the cam upgrade but I am also concern about reversion , I picked LSA 110 following what Dennis Moore recommends to get a bit more out of it ,agree I could have been more aggressive but having 4 kids (3 thru 13 years old) ,I won't be going top speed very often. Rather be conservative for now ,might regret it later ...I know .:thankyouthankyou:

If I get 400 hp @ 4500 I will be more than satisfied , thanks for your input.

Call Bob at Marine Kinetics, a phone call is FREE. Have a quick chat with him and tell him what you said here.

I have one of his cams and told him my boat was for pleasure use etc. I have two younger children etc. and told him I didn't want to sacrifice usability/idle/overall tame manners and to work with the parts I already had, much like you. His prices are slightly higher than an off the shelf cam, but you will get a cam perfect for your needs/wants. He can fill you in on pricing, and in my experience is VERY fair.

FYI his cam in my boat blew my estimate out of the water by close to 50 horsepower on the dyno, idles dead on at 650-700rpm and pulls like crazy just about everywhere. There are probably hundreds of his happy customers here.

Remember a phone call costs you nothing. And the added bonus of having someone who has built damn near everything to walk you through the process is worth more than the parts.

Are you actually going to put one of these on a dyno and tune it?

Or just drop them in and hope for the best?

I strongly recommend dynoing at least one and copying the timing and carb jetting to the other. This way you'll know exactly what you have and where it is.

Bob Madera is an excellent builder and you are getting very good advice to speak with him.

Uncle Dave

I have heard great things about Bob, and excuse my ignorance but what can be done by dynoing the engine besides getting accurate hp/tq ?

No problem.

It's much easier to setup, time and tune an engine in a controlled environment like a dyno room than it is in the boat.

If you have a problem like a leaking intake manifold due to a gasket shift during final assembly (happened to me with a 406 before) its much easier to pull the manifold and carb off and put everything back together in a dyno room than in your boat.

So how much are you going to up the main jet by?

You will use more fuel with more CI and new heads- how much more? Do you know-?

I know the answer- you dont know & you will be guessing.

You can easily make these changes on the dyno and see what effect they have instantly.

Knowing what your mill CAN make is one thing getting it tuned properly to that level is the real reason to spend a day in/at a dyno.

When you drop your mills into the boat they are tuned, running as best as they can, and ready to roll.

Call me "old school" but sometimes spending a little more on something like this can save you a bunch of headaches later.

Ever had a leak from an oil pan? pretty tough to fix that in the boat as well. Are you sure you wont need better crankcase vents now with your HP bump?

I juiced up a 406 went form external balance to internal and from a solid to hot hydraulic roller and the mill made much more power torque and started pushing oil out the one breather I had. I was able to figure out I needed better crankcase ventilation after I fixed the leaking intake manifold and it started making REAL power. Never would have found that out without a big mess and a ton of work had just stuck the mill in the boat and rolled.

Oh BTW- do you have a plan to cool down your oil now that you are making more power? I strongly suggest external oil cooling.

Uncle Dave

Uncle Dave,

You are da man!!

I will run this by my builder...

Thanks again

Thanks,

But more accurately I'm - the guy that already made the mistakes.

Uncle Dave

I can vouch for running the engines before plopping them in the boat. Mine runs good but I know it has more. Also have had the motor out 3 times chasing oil leaks like uncledave mentioned. If I had a dyno anywhere near me you can bet I would man up the $$$ and use it for a day. If you have one available it would be in your best interest to use it.

The dyno room is an important part of any real rebuild as that's where you determine weather your guy did his work and prior homework before or you are some unknown project- or guesswork.

Lots of things to go wrong in a rebuild like yours. I'm not trying to freak you out just help share a lifetime of experiences like this.

Another thing for me is the dyno room is where the engine builder gets his final payment from me. Unless he is installing it in the boat himself.

Until established in the dyno room otherwise- claims mean nothing. Results mean everything.

The dyno should be the "feelgood moment" between you and your builder with a trusted third party helping the both of you figure it out. Because you will be making changes and testing them and when the needles finally swing into where you expect them to be and the roar fills the room you know you got it.

It's not only worth every nickel you'll have fun and learn a lot in one day.

Uncle Dave

Dave,

In this case he is also installing them and by the way he is giving me 1 yr warranty on parts and labor.
Anyways, what is a fair rate for a day at the dyno?

I will be watching this thread closely...my engines are similar and our boats are close in size and weight.

I believe that cam is a flat tappet model...did you consider Comps roller?

I used Comps Xtreme Marine XR264 HR12 Hydraulic Roller Camshaft in my two 355's

Lift: .488"/.495"
Duration: 264/270
RPM Range: 1000-5000

Mine made 400 @ 5100 and 435 ft. lbs at 3200

People I have talked to swear by these rollers...makes a huge fat TQ curve.

As for dyno $$ ...call Chief and or Cobra...also Doller in Hollywood has one I think.

I might be test running engines this weekend if I can sort out some cooling system issues.

What drives are you running?

Depending on the operator and the sophistication of the room 5-700 bones.

Your guy sounds solid I hope your project goes well.


Uncle Dave

He selected PWR 1.5 ratio rockers , I asked for Scorpions but told me he couldn't get them , I reviewed them and looked ok, not cheap .

I have been to Doller in Hollywood , very impressive place, will call them ,thanks .

I do have Bravo 1's

Thanks for your input.

My guy has been building engines for over 30 years , seems very honest and patient as well , I made lots of changes from what he offered me originally . I will also have MSD ignition package. Does this MSD thing really work in improving performance?

I keep you all posted. Thanks again.

merc's thunderbolt is a very solid, dependable marine ign that has an advance curve that is about optimal for boats. i don't think you will see an improvement from the MSD's. let us know what kind of speed-rpm numbers you get, and what props...

Unless the Merc system is failing you wont see an improvement.

I went through 3 engine rebuilds with a thunderbolt system from 91 that worked great for 19 years.

I just switched to the marine MSD 6 in my small boat and it works beautifully, but isn't any "better" than the thunderbolt system when it was working properly- at least that I can tell.

Unless you get the rev limiting version you wont see any diff.

Derekncathy is correct.



UD

I visited doller offshore last year when on the sunny Ilses to Bimini trip.

Mindy is a good business woman and has competent help.

Id trust them.


Uncle Dave

Derek ,

I am anxious to see those numbers, will post them as soon as I get the boat on the water, probably 10 more days...

Dave ,

I have not met Mindy, but Mac seems to be a great guy.He has been there a long time I heard.

fixx
 

is this the same boat that had big blocks but sat to low in the water and you were worried about water goin into the engines?

[QUOTE=mrfixxall;3736475]is this the same boat that had big blocks but sat to low in the water and you were worried about water goin into the engines?[/QUOTE

Same boat !!! yes unfortunately 454's had to go, got 100% of my money back and started all over with this other Builder from Miami (Power Source Distributor), it is taking some time but John is helping customize this project .
Very patient guy .Nice.

So now i contacted Bob Madara for the cam, hopefully we can get something done and be on the water soon !!!

this time going with SBC's and Stainless Marine exhaust to avoid problems.

fixx
 

[QUOTE=Diego9040;3737145]you called bob,,that is the best thing you could have done for those engines..when ordering your tails for your boat tell stainless marine that you want to go a little taller on them to prevent the water from going back into the engine's..

btw what you doing massing around with the 383's,,you need 2 of thease that they sell..
lol
http://www.powersourcedist.com/6_0__364_.html

[QUOTE=mrfixxall;3737168]Those are nice !

Yes , Jerry at SM will build custom risers, as tall as possible , I do not have much height but they will have a curve and will dump water much farther from engines . Plus I am shaving close to 700 lbs from the last 454's I had (330 hp) by going w sbc's ,aluminum heads,and SM exhaust ,I know I will have to flush religiously w these heads but It should be ok, right?

fixx
 

[QUOTE=Diego9040;3737399]alunimum heads and salt water?? see what they will charge for a closed cooling system also..would be wise ,you can plumb the manifolds into the closed cooling to,and just run the salt water through the riser pipes,then all you would have to worrie about is the closed cooling cooler and the riser flush which wont take as long and you wont have to use as much salt away..your engines and gaskets will last 5 times longer as well..

definately closed cooling. even if you hafta scare up old stuff and plumb it yourself. where is exhaust on Nova ST's. my Nova III had them on the side like 4winns libbys. took water in and killed the engines in 1 week at jersey shore. now they are above platform. kinda ugly, but got the boat back cheap...

Had a conference call today with Bob Madara and my builder John Hernandez from Power Source and most likely we are going to work with Bob on 2 custom made roller cams for the 383's , I knew about Bob from before but the push I got from this thread really motivated me enough to call him and make this happen.

Bob will be calling me tomorrow with all the final details and pricing ,ehheheheh, hope I can work it out with him and close the deal. I am really stretching myself with all of this, hoping it is all worthwhile . Thank you all again.

Outstanding!!! Looking forward to more on this....roller is the ONLY way to go and with a custom grind from a pro like Bob Madara your 400 + horse dream just became a reality.:evilb:

:ernaehrung004::ernaehrung004::ernaehrung004:

Definitely , it made sense to call him and it is probably the best to wrap this up.

Trust me, you will not be disappointed!!!