540 prochaged or 632 n/a
 

i am looking for around 850 hp. there are two engines i am look at for about $20,000. the one is a 540 with a prochager with 5-7 pounds of boost. the other is a 632 n/a. both engines use all the good parts. which way should i go or is there any reputible engine builders you would suggest for the same price or less. number one is reliabilty. no blowers because i want to keep my hatch without holes.

Go with the procharger
 

I would say go with the Pro Charged 540. First of all its a 540ci. motor, and would not have all the exotic parts that the 622 ci. motor has. I have had my experience with large CI Naturally aspirated motors, and although they sounded cool, they were too much maintenance. The last one I had experience with was a 598 CI, 850hp motor. It had the best of everything, Lunati, Dart Big Chiefs, etc. One motor popped after 10hrs (Dropped a Valve), the other one was useless when the owner blew the drive, and never checked to see if water was leaking in the boat, and it sank. Also we had to spin the motor like 6300 RPM's

In my opinion you can get more hrs. out of the 540 ci. with the Pro Charger, than the 622ci. I may be wrong, but that is what I learned from my experience.

Besides to make that much HP, the 622ci would have to turn a lot of RPM's. In a boat, I believe High RPM's over a long period of time spells disaster.

Personally I would go with the 540's

I currently have a Merlin 632 10.5:1 that makes 850 hp @6000 rpm and 820#TQ @ 5000 on pump gas. Here's the combo; Dart 360 fully ported and polished heads (flow mid 420's) Dart tunnel ram; 2X775 Race demons; Solid roller cam 280/288 @.050 on 115 C/L with .740 lift. Solid roller lifters WILL NOT live in this environment beyond 10-30 hrs. I've had major valve train issues (lifters) and have switched to the Schubeck radius lifters (basically a "high tech" solid flat tappet design that is "radiused" to run on solid roller cam lobes) with good luck so far. (I gave up about 20 hp at the very top from 900 @6700 but took out .040 lift, Schubecks make BIG power to say the least.) You also will need to change valve springs every 50 hrs. So your maitenence will be mostly valve train related. If you tried to go the hydralic roller route for more reliability I think 775hp would be about all you would see. Cam selection is critical to bleed down cylinder pressures when you run over 9.5:1 CR on 93 Octane.

Although I have no experience with Procharged motors I think they CAN BE more reliable. First you'll be able to get away with spending a lot less on heads and will be able to run a hydralic roller set-up. If you go with a procharger its almost mandatory you go EFI which will be costly. I know several people who have tried carbs with pro chargers and have had very bad luck.

Let me know if you decide to go the 632 NA route and I can help set you up with a combo that will make the power you'r after.

vip thread!
 

very important thread!
barry I also have the same confusion..(not planning to buy soon)

charged or big cubics?? or maybe both..

I have no experience in charged engines may be thats why big cu's look stronger to me like they say nothing beats cubic inches.

540 & stage 4 procharger. Only mistake I made is I have too small of heads on motor. I tried to remember why I went with he heads I got (merlin 310 VR cast iron) & remembered I started to build a 502 but changed directions & went 540. I was going to go & change & put AFR 335 CNC heads on this motor but decided to just pull this motor & keep as spare & build a 572 instead. The stage 4 has twin carbs. Last year I decided to try the carbs & if I had problems I would go with EFI. After this year I am going to stay with this setup. I have had no transom soot.

The 540 pro charged motor would achieve your goal easier, but the n/a 632 could be real sweet. If you go 632 and stick with standard (non Big Chief) heads there shouldn't be any more or less reliability issues than a 454, 540, 572, etc... I have heard of numerous valve train problems with big chief heads on marine engines. The valve angles on those heads are great for making power in short spurts, but haven't been very successful on engines that don't get rebuilt every 2 HRS, or 100 passes. I think it would be cool to build a 632 and disguise it as an HP 500. For $20,000 plus exhaust you can get 850 out of either combo. On either combo, do your research on the heads and the cam before you buy. Good luck!

I am partial to N/A engines with BIG cubes vs the super charged route. N/A engines are a simpler set-up i.e., less pullies, etc. Besides, although they have come a long way with super chargers for the marine crowd, they're still much harder on parts than N/A engines. Plus super chargers require more maintenance, teardowns and parts replacements. Just one man's opinion of course.

It's nice to be able to have a choice between the two though!

:)

I am very happy with my procharged 502s. They are carbed and I have had no problems with reliabiliy, idling, starting etc. Except this season the primary float has been sticking. This has happened after both motors were blown up, by operater error not cause of set up. Now they are balanced and blue printed, heads ported, polished, and a valve job. Dynoed @ 640 HP @ 5700 rpm. The rest of the motors are stock componants, except exhaust. The only maintenance I do is changing the oil.

I personally think there is too much involved with building a big HP N/A motor. The gains achieved with supercharging are far greater than all the aspects inolved with the big N/A's.

In both cases the initial set up is the most important.

You're right there is a lot involved in building a big HP/big cube NA motor. But there is also just as much if not more involved in building a blown motor. My feelings have always been that many people go the blower route to compensate for sloppy and/or inadequate parts selections for heads/cam, etc. Blowers can be a cheap fix to add to a "stock" set-up for some instant HP gains. Its pretty easy to throw a 6-71 on a 502 mag for instant power...but look how much you're leaving on the table. In my opinion if a "blown" 540 was built correctly with good heads/cam, etc I would be disappointed if it were not making close to 1000hp on pump gas reliability.;)

me and kaama have talked about this topic befor, and though we do agree on a lot of items, i tend to lean a different direction on this one. i feel “power is power” meaning that if i’m making 700hp with a na or 700hp with a blown 540 there is going to be the same amount of pressure on pistons, rings, bearings, ext. because i have to move a certain amount of fuel/air though the engine to make 700hp. where i feel the sc has an advantage is it dosen’t need to be run up to 6000rpm to move that amount of a/f. i remember reading somewhere that all other things being equal, a motors wear increases by the square of the %increase in rpm. that’s why diesels last so long even with their extremely high compression ratio and most are supercharged they run at low rpm’s and last for ever compared to their high revving cousins. where the problem comes in is when someone makes 700hp @ 5000rpm with a sc then continues to rap it out to 6000 rpm. of course this is just one man’s opinion.

;)

Another way to think of it
 

Another way to think of a blower motor (roots style) just ads Cubic Inches to the motor anyway.

Believe me, I love big cubic inch motors. But also when you go big cubic inches you have more weight in the rotating assembly, tighter clearances, and if its not balanced it will blow up. Out of all the fastest offshore boats made, what do they use. Most of them to my knowlege are supercharged.

Large cubes sound awesome at idle!! But the sould of that blower whining also sounds awesome!! Its up to you, there are pro's and cons with each one. Personally I would go with the Blowers, parts are easier to find.

Are other people getting "“power is power” " When they read Dean's post or is it just my 4 computers? I first thought is was my computer but have been on others & they are the same way.

Turbojack
 

sorry, that’s what it says.
i’m sure that is REALLY bad terminology but i couldn’t think of a better way to say it.
what i am meaning is, that just because an engine is supercharged shouldn’t automatically equate to more engine wear. all other things being equal, it takes the same amount of f/a mixture to make each hp whether it’s sc or na. so if you’re igniting the same amount of f/a on top of a piston (whether it’s pushed in by normal barometric pressure or pushed in mechanically by a sc) it’s going to drive the piston down with the same amount of force. the sc obviously does produce an amount of drag on the crankshaft, but from what i understand it’s minimal (less than 7% @ normal drive ratios).

Dean- What I am getting on my computer when you post is all kinds of weird hash marks, squares & other weird symbols in the middle of you posts. Looks like you are posting in code. That is what I was referring to. I just cut & pasted what I saw on my computer. "power” " is translated on my computer as the word power with some weird marks with a square at the end

Sorry, I guess I did not make myself clear enough.

jdnca 1

How many hours do you have on the Schubeck lifters? What valve springs are you using and why do you have to change them after 50 hrs? Please let us know how it works out.

JimV;

I only have about 4 hrs on them so far. I broke my last roller lifter after only 7 (broke the lower body just above the axle out) so we'll see. I think idle time and "too much" spring were just killing the traditional solid rollers. I got about 45 on the set before that. (needle bearings) I was running the comp 948-16 springs which are 340# on the seat and close to 950# opening. This time around I went with an the Erson E915170, they are 280# seat and around 780# opening. The Schubeck lifters weigh less than half of a regular roller lifter so you can get away with a lot less spring. I checked my original springs after about 55 hrs and found they were sagging by about 20% on the seat so I thought it was time to change them out. Initially I went with the comps again, but then broke my last lifter and switched to the Schubecks and lighter springs. Joe claims I should not have any more issues with lifters or wear to worry about for at least a few 100 hrs:cool: I'll believe it when I see it.;) and hope he is right. Big duration/lift solid rollers won't live in the marine environment in my opinion and based on my experiences. I think if you keep max lift in the .700 area with durations in the 260's to mid 270's with relatively light springs and limit idling a solid roller will work just fine. The 502 I had in a previous boat, ran a solid roller 252/258 @.050 .680/.708" on 114 cl and had no issues in over 60 hrs.

jdnca1,

What diameter lifters are you running? The last price list I got from Schubeck only listed .842 diameter lifters for BBC. Is this the same size you have and do you know if does he offer larger lifter in the radius style for the BBC?

Wette Vette,
Can you expand on the problems that you have heard about with the Big Chief heads?

Thanks

Dick

What's it going to be big guy....
 

Cubes or Supercharged :confused:

Either way it looks as if you will be going around me THIS year:(

Don't forget it cost horse power to turn the blower.

thanks every one for your replys. i believe i am going to use my current 540 block and crank and go with the procharger. any more replys would still be greatly appreciated

Barry, I assume you are going to be carb'd on this....I would highly suggest you send your carb to Dean Nickerson to modify. He will fully flow the carb, square it up, fix the air bleeds, etc. He did mine on a full roller454 and all I had to do then was adjust the idle speed 100 rpm when reinstalled. No over-rich condition, black transom or fouled plugs....EVER. It started like it was injected...instantly. No one does it better!! Glad you are going the P'charger route as your outdrives will last a lot longer!:D

at this time i am considering going with a arizona speed fuel injection to overcome some of the posssible problems of a carb.

Barry.... I caution you about EFI.....
it happened this summer...meltdown an engine due to an injector stoppingup/leaning out, and not at high rpm either, just 3000 rpm..... It won't ever happen that way carb'd. fuel pressure regulation is also easier on a carb version...7-8# versus #37-45#. A sudden lose of a few # of pressure is serious business with EFI, not so bad with a low pressure system. Heck, just a 2# drop in pressure can stop an EFI cold, it won't even idle. I would go with the carb starting from scratch, no ECM remapping to worry about either! Way too expensive a conversion. I am on #2&3 P'C's now with EFI and wish they were carb'd!
My 02.

Nickerson
 

I have had 50% luck with the nickerson's. The carbs run awesome when they are brand new, you can't beat them. But he does so much work with the mixture circuits try adjusting the mixture. You will never get it the same again, unless you have a flow bench. I had 3 nickersons I rebuilt once, and had to send all three back to him to get the idle mixtures correct. He told me that they would be very hard to adjust, and he was right.

Not to say he doesn't do bad work, but have fun rebuilding one.

Mr. Gadgets, see Powerboat magazine issue August 2001. Cobra has a small explanation on some of the problems they had when they used Big Chiefs. At around 40 HRS the roller rockers would loose their needle bearings and would destroy the motor. They have since changed to standard BBC heads and the problem went away. The Big Chiefs have some wierd valve angles which make them very powerful, but harder on parts than standard heads. Also Big Chiefs work best with huge lift that can only be produced by a solid roller or perhaps a Schubeck 1" radius lifter. Huge lift and pleasure boat shouldn't be used in the same sentance.;) Dart or Brodix make conventional heads that will support the wildest pleasure boat engine without the added valvetrain problem potential. Just my opinion.

.... I have found it!!!!!!
the answer is: blown 632

;)

Sorry but I guess I have to defend the Big Chiefs. First I am on my third season with them on some 507 cu in motors which made 750 at 6700. With a hyd roller made 650 at 5500. Proper initial setup is critical, as with any package. Then you need to maintain properly. Initially I had to much spring pressure, no additional oiling and life was around 25-30 hours. KE then set up. Titanium on intake, a Ferra Comp+ on exh. Solid roller. Here's the deal. I am running over 100 hours each season, this year at 120. My spring pressure is at 210 at seat. Isky tool room steel springs. Cam is .678/.651 and .399/.383 at .050. Lifters are Crower severe duty with the extra oiling mod. Here is a major difference, I have valve spring spray bars and KE installed a spray bar in the intake valley to keep lifters cool at lower rpm operation. Max rpm I run would be around 6100. I normally cruise at 2800-3500. Although we did run up to 6700 on dyno.

In winter, the heads come off. Jessel goes over the rockers. We check out springs and touch up valves/seats. Motors currently have Kinsler inj and are very fuel efficient, even with dominator. I average 26 gallons per hour total usuage (for both motors) with about 10 % idle time and running rpms at 2800-3500. At 6000 it is like any 700 hp motor.

For what ever it is worth, I think Big Chiefs are a very efficient cyl head and can provide good service life if given half a chance. Granted, a pair of 10-71's on top would also be nice!

Talked to my marine mechanic today. This and that...
 

asked him what route would he go. He said in about a 1/2 second. Blower
I asked why and he said you have to turn a N/A so much rpm to get the hp out of them. He said he liked Vortex if he didn't want to go thru the deck.

I have 632 cu in 850 hp and have not had any problems
they will last forever at 5000 rpm which is where i run them
tyson 417-437-0665

[QUOTE]Originally posted by jdnca1
[B]I currently have a Merlin 632 10.5:1 that makes 850 hp @6000 rpm and 820#TQ @ 5000 on pump gas. Here's the combo; Dart 360 fully ported and polished heads (flow mid 420's)

jdnca 1

What intake volume did you end up with after porting? Those are some impressive numbers for a 360 cc head. At what lift do they flow mid 420's? curious

Bob, sounds like the Big Chiefs are capable, but it also sounds like a lot of effort every season. What springs are you running with that solid cam? My cam has similar lift and I am just curious. Thanks, Craig

nice engine :apache77

thanks timucin

Wette Vette/

We ended up using the Isky 9385+ which is a tool room outer and a normal inner. Put them in at 215# at seat. First attempt was with Gold Stripes 9945 , tool room inner and outer, in at 250# at seat. From what I can tell the Big Chiefs are probably worth 30-40 hp over a 360 at 6200? I have them because they came with package. Would I put the bucks up for new ones if I were building new motors? No. But, they do make hp. KE did some 588's like my package and made 714 @ 5000, 790 @ 5500 855 @ 6000 and 873 @ 6500. With 632 or so they should be up around 900+ at 6000? Not bad for a natural setup ( Kinsler FI). With any head I guess you would need to change springs and look at valves after 100 or so hours. If someone can figure out a way to make 850-900 hp and get 200-300 maintenance free hours life would be great!

jdnca 1

What intake volume did you end up with after porting? Those are some impressive numbers for a 360 cc head. At what lift do they flow mid 420's? curious [/B][/QUOTE]

Intake volume is 390. Heads had full CNC port and polish at Dart with some additional hand blending by the builder. 425 flow is @.800" lift.

Bob,
Did you have problems with the 9945's? I am running comp 951 pacaloy springs and they were installed around 235 on the seat and they are now (25 hrs. later) at 220 on the seat. I have heard good things about the Isky springs and may consider them when these 951's are spent. I also may just put on a new set of 951's if these hold up another 25 hrs. or so without breakage. Just trying to get some more info.
Craig

If you guys want some cool valve springs check out www.lsmeng.com they will custom make you a valvespring per your valvetrain requirments. And if you really want to spend some money they have titanium springs.

Years ago I remember alot of hype over a rev kit that was being introduced. It utilized a plate that fit below the cylinder head with springs that pushed directly on the lifter. The idea was to take some of the pressure off the rocker arm. Anybody know what became of this kit and why it hasn't caught on?

Wette Vette/

Last I heard, a head shop down by KE's was really sold on the 9945 spring and a lot of guys ran the 9945 spring in the old A boats and had very good luck. Isky swears by them. I believe they are the psi spring. They were just too much pressure for my application and Isky said I did not need them. If I were going to run up around 6500 for extended periods then I would have to go there. Might be a viable option with KE's spray bar.

I built my engine to a 604 c.i. and have had no valve train problems,the block is a raised cam 10.2 merlin,i don't know if that is for better valve angle or more clearance for a bigger cam.But i
run a .629,.639 lift with .248,.252 dur.at .050.Cam is full roller.If
you guys are running into valve problems tell me why you think
yours are failing versus what i am using.Thanks