Upgrading Engine Ideas
 

We currently have a 2000 Checkmate 259 Convincor. We purchased the boat new in 2002. The engine (454MAG MPI) and drive (B1) have 275 hours. The boat had an engine upgrade kit installed at about 215 hours.(cam, exhaust, valvetrain upgrade). The engine was dynoed after upgrade at 461HP (5100RPM) and 514lbs/tq (3800RPM). Recently the engine lost power and a compression test was performed. Here are the numbers by cylinder: 1-150,2-150, 3-130, 4-100, 5-110, 6-85, 7-170, 8-85. Any thoughts on what could be wrong? Anyway I am using this problem as an opportunity to upgrade our power. I would like to stay NA and go to a carb motor. Should we try and salvage the motor we have or go to a larger displacment motor? 600HP is the goal number. The boat has full hydraulic steering and HP tabs. The engine must be user friendly as this is a family boat. Wife needs to be able to drive it. The boat will be used for cruising, some water sports and an occasional WOT run. The project budget is 15K.
Thanks in advance,
Rob

I would say your headgaskets are toast. Sounds like you did the exaust and cam already. I would pull the heads and see what you have then get them to Jim Velako for a port job. Upgrade your head gaskets to atleast felpros.

Before you take anything apart, run a leakdown test. That will help identify where your problem really lies. Then put a dial indicator on all the rockers and see if you may have lost a cam lobe or two.

600 horse is going to be next to impossible to get out of a NA 454 that will still run on 93 octane- and it still won't be terribly wife-friendly. 600 out of a 502 is still fairly warm and the cam you'll need to do it is going to necessitate new exhaust that will be resistant to reversion.

Keep in mind, your standard Bravo isn't going to like 600 hp. Not at all.

Well put.. To avoid reversion and that wild cam you should just go w/ a 502 block and then stroke it to a 540. I just seen a couple 540 make well over 600 n/a.

We are building a 502 complete with aluminum heads,hydraulic roller cam,world intake,holley hp carb,mostly new parts,will have it on dyno soon should be around 600 hp,motor will be ready to bolt in ,complete with sm exhaust.Much better than working with your 454 and well within your budget,if interested dave 410-956-5381

The lowest # being #6 makes me think your motor had a lean spot somewhere and I would suspect your valves got hot and tulliped or pistons burn't/head gaskets burn't. Being it lasted 60 hours before doing it I would suspect maybe your fuel pressure was a little low recently or you got some gas that had a ton of alchohol in it or less octane then what it was advertised to have had. I like 502's and 540's but you could put a stroker crank in your 454 and build a 496 that would make 550-575 hp fairly easy. The real thing is weather you get aftermarket heads or not,wags 382 built some carbed 502's w/afr heads that made in the 575 range if I remember correctly and still had fairly small cams with excellent idle and tq,Smitty

just had mine done over the winter, same boat except 502 mpi. world steel heads ,cam, stainless marine exhaust, cool fuel system, ecm remap. retained the stock injection and dynoed out at 552 hp w/ 620 fp of torque. boat gained about 10 mph on top with nice accel and mid. can run about 74-76 mph top. next move is external steering and some k planes. your hull is only designed to go so fast, so keep that in mind.

To get 600 out of a 502, you'll need a good set of aluminum heads and a cam right around the Crane 741 spec. Plus compression pushing close to 10:1. Tube headers wouldn't be necessary but the only manifolds that will support that power would be the Eickerts or the SM's.

As others have stated getting 600HP out of a naturally aspirated 454 is going to be tough. I just redid my 454's and I got 590HP with solid roller cams, Jim Valako ported steel Merlin heads, 9.6:1 compression, Holley 750 carbs, Jim V ported my Wieand Stealth dual plane intakes and on 93 octane.

With your budget of $15K I would stroke to a 496, and Call Jim V about what heads and cam combo you want with how much power. He can order the heads and port them for you and send them to you. I know he has a recipe for a mild 496 that is in the 600+hp range.
JimV (616) 889-0928 you will be well under your budget of 15K

Those are about the exact same dyno numbers as my cousin's 461cid engines modified from the Merc 330's----461hp @5100rpm and 510lbs of torque @3600-3800rpm. Flat tappet hydraulic cams, 8.6 cr, oval port GM old (semi-open chamber) truck heads with larger valves installed and bowl/pocket ported by JimV with dual plane intakes and Holley 800carb. Jim also did a "bore notch" job on the cylinders which is supposed to be good for about 30hp/tq or so.

I am curious as to what kind/brand of exhaust system you now have on your engine...???

I once owned a pair of 468cid engines in my boat that back in 1994 supposedly made about 620hp @5500-5700rpm with tubular dyno headers on someone's dyno in Chicago....Merlin oval port heads, 2.30" intake valves, bowl/pocket ported, mechanical/solid roller cams 248*/254* @.050" lift on 110* lobes, 9.5cr, Dart single plane intakes, Holley 850cfm carbs. I honestly don't know if those HP figures from the dyno are with all belts, water pumps and pullies, etc or not---but I kinda doubt it.

Those were some pretty respectable numbers back in 1994, but the guy who owned my boat before me with those engines was ALWAYS changing out new valves springs, and lifters about evey 50 hours or so, but it was a maintenance nightmare. So, 600hp out of a naturally aspirated 454 can be done, but it isn't going to be user friendly. You'd get there a whole lot easier if you added a superchager to your engine. Just make sure the rest of your engine (cam profile, comp ratio, etc,) is compatible with the use of a supercharger....and you'd still be way under $15k! :)

FYI, I know of a friend who had just built a pair of really mild 509's with B&M 420 Mega blowers, hydraulic FLAT TAPPET cams, bowl/pocket ported GM rectangle port cast iron heads that made about 665hp @5600-5700rpm with 4-4.5lbs of boost on Wesseldyk's dyno with all belts, pullies, pumps, assesories, etc.

Do you really want to trade valvetrain reliability for 35 HP? Solid roller cams have very aggressive ramp profiles that are very hard on pushrods, rockers & springs. If you're not diligent, you'll end up with valves through your pistons. On flat tappets- you might get the peak horsepower out of the motor but unless you run flat out all the time, your motor is probably missing out on a big, fat torque curve. You can get 800 HP out of a 454, but it won't pull your boat up on plane.

In addition, it doesn't really matter what the motor dynos at- if you're using dyno headers. Mercruiser manifolds on a 600 horse motor makes it a 450 horse motor. The only thing that's going to be the equivalent of dyno headers is CMI Tractor headers. Everything else will rob HP.

The best thing you can do is have a long conversation with someone who specializes in cam/top ends for marine engines. I'd suggest RMBUILDER (Bob Madara). He can zero you in on exactly what is going to do what for you and grind the exact cam for the application. And it won't cost anymore than ordering it from Summit.

Thank you for the responses. The exhaust on the boat is Stainless Marine. I hope to keep the exhaust and spend that money elsewhere on the motor if the exhaust can handle the added power without strangling the motor. I am leaning towards a larger displacement NA motor such as a 540. I worry about the drive with my power goal. Maybe a 502 with less torque and 550HP would be better for this application. I am also interested to find out what happened to the compression in the bad cylinders. That would be a large concern if a batch of bad gas can toast a motor! Spend 15K and next year have the same thing happen, bad for marriage.

What tails on the SM's? The short one's won't work with much cam.

On your drives, it would be a good idea to redirect some of your budget to updates & freshening. The bravo likes RPM less than it does torque.

Hye Rob,

Wow that sucks to hear. Things seem to have been going well with the new upgrades. I agree with everyone else, 600 hp from a 454 will be a bit hard to get. Then the drive issues come in to play. Personally, I am not a fan of fuel injection on modified engines unless you can tune them yourself and be well experienced at it. A carb is alot easier. If you do decided to go with a carb engine, one thing nobody has mentioned... You will need to upgrade your entire fuel system. Expect to start at the tank, run all #10 lines, a good electric and mechanical pump, a return regulator, etc, etc. As you know, I did all this on my boat, same exact set up you will need. I can offer you my suggestions if you want.

6 and 8 cylinders low... as was said, pull the head and take a close look. It will be the only way to know for sure. What head gaskets did he use when the upgrade was done?

A 502 with 550hp would probably be a good bump over what you had and a little easier on your drive.

Smitty(articfriends) knows his stuff when it comes to both engines and drives.

Occasional WOT run?! :Whatever: :drink:

Do a leakdown test. My guess is your problem is in the heads. Was the A/F ratio ever dialed in with the boat in the motor? Who knows how lean it was running until you added the high pressure fuel pump and regulator.

Sorry to hear about the motor. Saw your boat sitting in the grass last Thursday when I got my boat off the lift for a river run.

Hey, just thought of one more thing to check. Make sure your hatch ram did not finally wear a hole into the top of your intake. Last time I was on your boat that ram had a pretty good divot out of your upper plenum. Not sure if a hole there would be the cause of your problem but it won't hurt to check to make sure there isn't a hole there now.

Good points Beadman. After reviewing the finances I think I am probably going to modify what I have. I am hearing a good set of aluminum heads, 10 to 1 compression and a stout roller cam should get the little engine that thought he could to 550HP and 600lbs of torque on 93 octane. That should keep the Bravo 1 from exploding for a couple hundred hours, I think. I am selling the fuel injection system and going to a basic carb setup. Am I crazy or just stupid?

I am finding out first hand that the Mag MPI intake on these really can't make power. We went through mine last fall using Tyler Crockett's cam and valve train, .030 over, 9.5:1, RHS Aluminum heads, and we made 501hp on the dyno. The power flattened out at 5200 rpm and that was all the intake could do. I am most likely going to switch to a single plane intake efi system like the Edelbrock Victor Jr setup that uses a 1000 cfm throttle body and port injectors. I'm also thinking about building a new 555 CI short block to go with it if I can sneak it under the wife's radar!

Short answer is the stock intake pretty much sucks. A nice single plane with a carb would be better for making power hands down.

Let me make this clear, I do not suggest that RJBBC build a solid roller HYPO 454, I was using my build as an example to show him a hot setup and still NOT achieve 600HP

Are you saying that a reliable marine engine can't be built with solid roller lifters? You speak as if the engine will self destruct in 10 hours. It takes a little extra preventative maintenance and to be in tune with your engine. I have seen 100 hours on a solid roller marine engine that had never had a valve cover removed to relash the valves.(eventually the lash was to great and hurt the engine, LACK of maintenance)

I also personally had my merc 425's (hydraulic flat tappet) break rocker studs every other weekend (5 exhaust 2 intake) and grenade 3 lifters on me. (no maintenance needed on on hyd. flat tappet)

Sorry I feel this was directed at me, are you saying that with my near 600HP I will have troubles getting my boat on plane?? I have a boat load (no pun intended) more torque than I ever had with my 425's but now I won't get on plane? I chose to build a little higher revving motor with less bottom end torque so I can run a little smaller prop and save a little wear and tear on my drives.

Did anyone mention Mercruiser manifolds? He stated in his first post that he had upgraded his exhaust.



That is the best info he can get, talk to experts in the field that answers these question daily. That is why I threw out JimV's name. I'm sure RJBBC only wants to build this engine once.


1. Decide on Cubic inches. If you stroke to a 496 now you could use the same crank and rods for a 540 when you get bored with the 600HP and want to get closer to 700HP. (experts correct me if I'm wrong, same GEN block just 502?)

2. Heads for the build. Call the experts, I and others have used JimV with good results and he could probably tell what heads that would work good on a 454 build and later on a 496 or a 540. (probably Dart Pro1's 310cc then later port them out for larger CI)

3. Once 1 and 2 are decided call Bob RMbuilder, he has helped countless people on this site. I have never used him, but only hear good things. (but know what your overall goals of the build are,).

4. Fuel delivery I missed the MPI thing earlier, sorry. I know absolutely nothing about MPI. go carb :drink:

5. Exhaust, I'm kinda partial to the SM also.

6. 496, Dart Pro1's ported, 10.5:1, Manley 2.30" intakes, Ferrea 1.89 Exhaust, SRP pistons, Crane 741 or custom cam, comp springs, Merlin single intake and an 850 Holley. Should get you close to 575-600hp

I can only give you info on the engines I built for my own application, and I would not suggest a build like mine for the faint of heart. These engines exist and are running in my boat.

Sorry for a long winded post.
Good luck, keep us posted on what you build!

[QUOTE=Rookie;2650997] [Are you saying that a reliable marine engine can't be built with solid roller lifters? )

I said exactly what I meant- solid roller profiles have a more aggressive ramp profile and they're harder on valvetrain componentry. Simple physics. The faster and the farther you make something move, the more force required. Weight (mass) definitely comes into play here.



Sorry I feel this was directed at me, are you saying that with my near 600HP I will have troubles getting my boat on plane??.

Again, I said what I said. I used an example of a high RPM , high horsepower motor and how it wouldn't be particularly useful in an offshore boat. Peak horsepower at the sacrifice of a broad powerband has many unpleasant tradeoffs- nothing to do with you or your setup.



Did anyone mention Mercruiser manifolds? He stated in his first post that he had upgraded his exhaust.


Again, making a point that peak horsepower and dyno sheets mean little when bolyed into the boat. Dyno'ing a motor without the exhaust you'll be using in the boat is less than useful. As I mentioned, his exhaust is one of the better one's, but his engines won't make the same power as they do with dyno headers.

People make many mistakes on engine builds and upgrades. The biggest one is not being in close consult with someone who has done it many times with the type of boats we deal with here. I know several exceptionally accomplished racing engine builders- and not one of them has a grasp of how to make a boat go fast- because they've never done it. Boats are too different from race cars for those experiences to transfer.

With porting on the manifold and a bored out throttle body you can make decent power with a mpi top end w/good flowing heads,takes a little work though. I made 657hp at 5400 and 665 ft lbs of tq from a 540 w/502 mpi system on top w/afr heads and its only 8.2-1 compression,I can run it on 87 octane if I want,Smitty

Well said.

[QUOTE=Chris Sunkin;2651101]Great post. I am currently talking with Steve Schmidt Competition Engines out of Indianapolis, IN. They seem very responsive to my project. It appears they have a great reputation for building drag racing engines. They also sell marine performance engines and upgrade existing powerplants. They sent a competitive quote for a comprehensive rebuild on our motor. Bored to 467 cu. in. with new pistons, rods, rings, bearings, cam, intake manifold with porting, 950cfm carb, MSD ignition, valve job, mill & C.C., head porting running close to 600HP on premium fuel. What do you guys think? Anyone have any experience with these guys. They seem professional on the phone.

[QUOTE=RJBBC;2651266]Never heard of them. Make sure you get references. Remember, Baker sounded very professional on the phone too and sold Pratt a bill of goods that they never delivered on. Well over a year later and he is still trying to dial his 454's in.

[QUOTE=Knot 4 Me;2651355]Good point. I think I found the option I will take. ATECO Industries has a NA 540 with 600HP (5600 RPM) and 650 lbs./tq (4100 RPM) for 13K. The motor comes with a 2 year warranty. Bill has spent over an hour on the phone with me. I like the package and think it is a good fit. Anyone here on the forum ever deal with ATECO? I still have plenty of time to think about it. I am bagging the 2008 boating season. Thanks again for all of the insight.
Rob

Here are the specifications on the 600HP 540. Gen VI Block, 4.5 Bore, 9.8 Deck Height, 1 pc Rear Main Seal, Crank-SCAT 4340 Forged, Internally Balanced, 4.25 Stroke Rods-4340 H Beam, 6.385 w/ 7/16 ARP Caps Bolts, Pistons-JE Forged Aluminum 9 to 1 compression, Rings-single molly, Cam-ISKY hydraulic roller .578/.608 lift, 238deg//248deg duration @ .050, Intake-Single Plane, Cylinder Heads-BBC Aluminum 320 CC, 2.25 Stainless Intake, 1.89 Inconel exhaust, Rocker Arms-Scorpion Full Roller, Oil Pan-Canton 10qt.
What do you guys think?

RJ,
For what its worth, "Triple Digits" on this site has a 600+ Horse small block Schmidt engine in his boat. I've been in his boat at and it rocks!
I'm not sure, but I think Schmidt also warranties his engines even if racing. I would compare Schmidt's warranty with others. Good luck. Let us know what your choice was/is.
www.Steveschmidtracing.com

[QUOTE=RJBBC;2652088]Hey, there are plenty of boats on Dock 3 to hop on. Bud Friday this Friday. Come on down!

600HP 540, eh? Bye bye standard Bravo!!

Do yourself a giant favor and call Frank aka "10x" he is pretty well known out of Chicago with many of the offshore boaters and has the inside scoop of what is what and who is who with true hi-perf marine engines. I would contact him and ask who he recommends. He and several others have been through a TON OF GRIEF over there in Chicago with marine hi-perf engines. Before you make a decision I would call/talk to Frank. You will find him in the Chicago Powerboat Club section here on OSO.

Just a word to the wise....the last thing you want is finding out the guy/shop you chose to do your engines ended up being a disaster and a ton of grief!

[QUOTE=Knot 4 Me;2652603]Beadman, I am all over the board with a plan. I am not sure what we are going to do. The only thing that I am sure about right now is repowering the Checkmate! How much power or how to achieve it is up in the air. Will be driving to Destin on Friday for family vacation. I would like to make at least one Bud Friday this year, thanks for the invite anyway.

Thanks KAAMA. I have already sent 10x a message.

On that 540 build- that all sounds good. Couple of things I'd change;

Crane golds instead of the scorpions
Crane Hi6M instead of the MSD
AFR 315CNC's on heads
The new bulletproof Morel hydraulic roller lifter
Make sure the valves are manley or Ferrea, not Eaton

You should be very pleased with that combination. Now, look into drive upgrades.

(P.S.- $13K isn't a giveaway price. I'd shop some other guys on it. Gellner, Eddie Young, etc.)

Rob,
My personal opinion is to stay away from Scat or Eagle cranks. Go for the extra $$ and get a Callies. I agree with Chris, no scorpion rockers and stick with AFR 315 CNC heads.

What drive upgrades would you suggest? It has been suggested to put in a Bravo X conversion (about $1500) or just go right to the XR (about $7500). I have also heard I should keep running what I have until it breaks and then upgrade the drive. I am a budget boater, so if I can buy some time I would like to. However I do not want to consistently have problems on the water. Thanks for the info.

Thanks Vinny, I will take note.

What you do to the drives is dependent on you as much as it is on the boat and power. If you want to do full-throttle holeshots, if you want to do big wave jumping and you don't want to take the time and effort to learn and exercize proper throttle discipline, you'll shred the XR. Driven sensibly, the X upgrade will probably do you just fine. Merc outdrives like to be kept cool (drive shower) they like fresh oil and they like to operate inside their clearance specs. Essentially, you can keep one around with a little common sense on the sticks and regular fluid changes coupled with having them gone through periodically by someone that knows what they're doing.

I agree with you on the Eagle- I've seen some funky one's. The Scat has so far been reliable in the quality and durability department. The Callies is better, definitely, but at moderate power levels I've yet to see a broken Scat.

This is my Achille's heel on projects. It's constantly "only $500 more" until I'm into Sterling money into engines that were supposed to be "just warmed up a little".

Aint that the truth! :drink:

I completely agree with vinny and chris here,insist on quality parts,the afr heads are the key to making some good hp numbers plus a engine loaded full of the cheapest chinese/offshore imported parts shouldn't run 13,000,Smitty

I tried my damndest to figure out a way to make the same kind of power with a head other than the 315 CNC. There just isn't. They only look expensive. There's no better or cheaper way to make that kind of additional horsepower.