Hatteras 43C 1983 high performance

[giuseppe]

Dear friends the problem of my boat is that at full power the engines only reaches 2.000 rpm.I have 2 6v-92tac-2 high performance 500 shp?,allison marine gear 1.5:1,props 26x28 3 blades.I have checked the cilinder compression and they are ok.Do you have some suggestions.
Many thanks

[Genesis]

Any smoke at that 2000 RPM?

In order, check the following:

0. How clean is the bottom, including running gear? This is the obvious first start.

1. No-load RPM. If they don't turn up no-load to 2500 RPM, you will run into the governor. If you have no smoke at that 2000 RPM, this is a good bet. Note that you need the engines good and warm to do this test.

2. Airbox and airhorn pressures at idle, 1500 RPM, 1800 RPM, and WOT. Report back with them. You need BOTH airhorn (post-turbo) and airbox (post-BLOWER) pressures.

3. If neither of these shows a good cause, then you start with a full tune-up and injector short-out test.

DO NOT run the boat for significant amounts of time with this problem, if you are truly overloaded you could easily trash the engines.

I have these motors in my 45C, and know quite a bit about them.

BTW, 26x28 is a bit aggressive with that setup. My wheels are 26x26. You may need to have them repitched. It is important that you can reach 2300 RPM in gear and fully loaded, 2350 is better.

[George]

Agreed with Genesis, proping could well be the case, however how long have you run this gear and did it perform before? Another consideration that came to mind is a fuel restriction. I'll assume you change your filters on a regular basis, and all things remaining the same when you look at two engines performing exactly the same, I think fuel blockage. I recomend putting guages on your fuel system to measure if your getting a restriction. Also, disconnect your throttle cable from your govener, and manually raise your throttle to determine your WOT no load, reconnect your cable and make certain you get the same amount of travel and RPM. Lastly, have you checked your shaft RPM and does that coincide with your tach.?
You can either borrow or rent a strobe which will give you actual shaft RPM, simple to do. Set up with your partner a prearranged agreement to set the rpm at specific rpm's for a specific time and record actual vs. tach. This takes about 10 minutes per engine and be sure to check both.
Lastly, I think I said that allready, if one prop is out, that will put a load on the other engine and make it appear that they are both failing. If you have scuba, again easy to do a simple check. Get a 3' heavy thick aluminum strip and attach to your strut with a bar clamp at the closest distance to the prop blade so that the alum. strip barely touches, spin the prop and make sure all blades touch at the same point. Mark "Score" the aluminum bar so you can reposition it on the other strut equal or close to it's original position on strut #1. again, spin the prop and make sure all blades touch in the same way. That test can tell you alot about the health of your running gear.

[giuseppe]

Thanks for your answer.Yes i have some dark smoke at 2.000 rpm.The engine no load rpm is 2.500

[giuseppe]

thanks george

[Genesis]

You're overloaded.

Did the boat EVER turn up to full RPM?

26x28 is aggressive for that boat. I have a 1985 45C, which is the same boat basically, with the same engines. Roughly the same weight, etc.

I also have the original build sheets from Hatteras on the hull. It specifies 26x28, Michigan Wheel, 3 blade props.

I have those wheels, and a set of spares. Mine were repitched to 26x26, and that's as far as I'd ever want to go. I can just get to full RPM loaded. 26x28 would leave me about 200-300 rpm short, which is about where you are!

Since you have smoke, you are either overloaded OR you have an airflow problem. Black smoke = not enough air for the fuel being injected.

Thus, your first job is to verify the no-load speeds (you need a photo tach - DO NOT trust the bridge tachs!) and once you know the governor is happy, you need airbox and airhorn pressures at 1500, 1800 and full throttle. Note that when checking no-load you do it with the throttle linkage disconnected and your HAND on the throttle lever, so you can verify that it goes all the way to the stop. When you reconnect it you then verify that it goes all the way to the stop when you select full throttle at the bridge, and if not, you fix that too. You also need a fuel restriction gauge in the suction side of the fuel system AFTER all Racors but BEFORE the fuel pump - I want to know what your maximum vacuum reading is at full power, and whether the needle is jumping around at all (and if so, how much) or if the reading is stable.

With all these numbers I can give you a good idea where to start looking. Until you know if the engine is producing the right amount of boost, if the aftercooler is clear, and the fuel flow is ok you're guessing. You may just be overpropped, but you may also have a problem such as a bad turbo or fouled intercooler and without knowing what's going on you're going to spend a lot of time and money chasing this demon.

Let's not guess and instead diagnose.

[giuseppe]

Genesis,i don know if the boat ever reached full rpm because i just bought it.Speaking with the owner he told me the boat neve r reached the prescribed rpm but he also was not the first owner...I can give you some more data because i made some checking before i bought it:
eng sx: rpm no gear 2555;rpm max whit gear 1982;exaust gas temperature turbo sx 356 ° c turbo dx 349° c,cilinder compression left side 500,right side 500.
engine dx: rpm no gear 2548,rpm max whit gear 1950,exaust gas temperature turbo sx 276°c turbo dx 286°c,cilinder compression left side 480 right side 480.
What you think?
regards.

[Genesis]

Compression is good, but it won't be for long if you don't take care of this!

I still want those airbox and airhorn pressures, along with the fuel vacuum number. Before you repitch the props (which is what I think you're gonna have to do) you first must know that the engines are producing the correct amount of boost and getting fuel.

You are dangerously overloaded and if you continue to run the boat this way you WILL damage the engines.

This needs immediate attention.

[giuseppe]

Dear Genesis,actually my boat is on the ground and i will going to put back into sea next month so if you agree i think to change the wheels and once in the water proceed to the check you suggest me.

[Genesis]

If you're on the hard now, I'd repitch the props to 26x26.

That isn't terribly expensive to do. Just be aware that if the engines turn out to have a problem that you can correct (and need to), once you do then you'll be underwheeled and will have given up a couple of knots of speed. The good news though is that you'll have bought yourself a bunch of extra engine life doing it in that case.....

The boost numbers and such still need to be taken; aftercooler plugging is a major problem on these engines, and it needs to be monitored on a somewhat-regular basis.

[Genesis]

... there are a whole bunch of other relatively easy things you can do with these engines that will make a major positive difference in how long they last.

Let me know if you'd like the list. I own a pair and have made all of these changes myself.

[captcoop]

I have a 45C with this same engine/prop combo. I don't have a problem turning 2350rpm. I would say spend the prop money on a tune up. You most likely have one or two bad injectors. I have had new one's bad when installed. A tune up by a Detroit Dealer will cost less than new props. Good Luck

[Patience]

Genesis,

I have a 1990 52c with 892's. Would your modification list apply to these engines as well. If so, would you mind emailing it to me?

parkerhuddle@comcast.net

[Genesis]

.... The most important ones are, in order:

1. Remove the airbox drain connection to the crankcase. Route them to a crap can or, if your engines run relatively clean, to a bilge diaper in the pan under the engine. A stuck airbox drain check valve can cause (indrectly, if you have Airseps) a runaway and will trash your oil, which of course is real good for the mains. On the "V" series engines one of the check valves is behind the starter and extremely difficult to get to. Get it outta there and route the connections where you can access them easily. It is CRITICAL that the airbox check valves close when under power. You need easy access to them to do maintenance, and they're a bitch to get to where they are as delivered. These need to be cleaned on every oil change, and replaced if they will not seal. You simply have to put them where they can be accessed easily for decent engine life. Detroit routed them to the pan because people complained that their engines were "dirty", and further, if they went to a crap can then that was another maintenance item to look after - so they ran 'em back to the crankcase. In short, convenience over proper engineering and maintenance.

2. Ditto on the returns from the Walker airseps if you have them. Returning that garbage to the crankcase is not a good idea. Worse, if THAT check valve sticks open, you risk a runaway as oil will be sucked right into the intake! Second, regularly inspect the vacuum limiters on those airsep systems. A frequent cause of turbo damage and aftercooler plugging is oil pull-over from an Airsep that is not properly limiting crankcase vacuum. Even better, ditch the airseps and get a set of Racor CCVs instead. While their return is supposed to route back to the crankcase, and its less of a problem due to the way their system is designed than with Racor's, I wouldn't do it with theirs either.

3. Make VERY SURE you have no exhaust leaks. They are deadly to Detroits.

4. If you're willing to spend a bit of money, install a step-up blower drive gear. This will significantly improve ventilation of the engine and reduce EGTs. The gear is about $100, and requires recalibration of the tune-up (it will change the governor speed, thus requiring a reset of the no-load, and that requires a reset of the entire tune-up. Don't go too far with this (the "more is better" argument does not apply completely here), or you can make it impossible to get the governor back in sync.

5. Remember that the aftercooler is UNDER the blower and requires service every 2-3 years in most boats. Its a pain in the butt to get out; pulling and replacing it is a two man-day job, since you need a full tune-up (as the governor comes off with the blower, and you have to disconnect it and thus the tune now must be re-done), plus you have to drain the cooling system, but if its plugged you will see high engine temperatures and poor performance. The way to know what's going on with it is to take airbox pressure readings plus airhorn pressure readings. If the airbox pressure is equal to the airhorn when on boost, its partially plugged (it should be greater, but only by 1-2 psi.) If the airbox pressure is LOWER, service is required. Don't ignore this one.

6. NEVER shut down hot. It only takes once to start the process of self-destruction on a turbo. Also, don't do "slam the throttles" holeshots. Ease her up and ease her down instead. Your engines will thank you for that.

[mikfinf16]

George,

I have old (1978) Covington twin dry turbo 425 HP 692's in my '73 45C. Are you aware of any ways to increase HP on there engines?

Thanks

Mick

[Genesis]

... don't. Service life will suffer. At 425HP you have some sweet motors that will run 3000+ hours with proper maintenance. Go to 500HP, you cut your life to 1500-2000 hours between overhauls with proper maintenance and increase the stress and thus decrease service life on everything.

If you're hell-bent on ignoring me, you can go to 500Hp pretty easily with bigger injectors (7045s). Make sure your cooling system is up to snuff. I'd also install step-up blower gearing to insure enough airflow. This is the setup that I have, and while I CAN go further, I'm not about to. You need to make sure you have marine heads though, or you'll eat the valves doing this.

Beyond 500HP you need advanced timing and a bypass blower (to get to 550HP). That too can be done, but I wouldn't. This step is, IMHO, not worth it, as you are getting dangerously close to "hand grenade with loose pin" territory.

550 is "end of the line" for non-electronic engines, and IMHO its beyond safe limits.

[George]

Mick,
Genesis is king here and there is some good advice on other engine web sites such as Boatdiesel.com. I sold my 550 HP 6V92's to a guy with your engines. He took off my air systems and cooling systems and refit onto his boat. He spent considerable $'s and frankly speaking, did not give me the impression he was over elated with the outcome. I just repowered with Cat C-12 and cruise comfortably at 1900 rpm doing 28 Kts. Huge investment which not all people are willing to do. The Covingtons are tricky to convert, and in my experience was not really worth the pain of knowing to well, and swallowing of a cylinder 70 miles off. In my mind, if you really want to go faster, more reliably, consider factory rebuilts with warantee's as a cheaper way to go. You've got plenty of engine room space, but your going to find, on the older 45's that your shaft angle is going to prohibit you from wheeling to meet the desired HP.
Good luck.

[436506]

Guys,

Thanks for the sage words. With the price of fuel maybe I'll spend more time trolling than going.

I talked to Daniel at PC Industries, i.e. www.powerlinecomponents.com and he offered to rebuild my engines to specs at $8800 a piece or exchange long blocks for about $6500 each plus shipping. Any thoughts on these guys out of Wyo. (fomerly Lousyana)?

George, your C-12 mod sounds awesome. Any problems with chine walking? Did you install lifting rails?

Cheers,

Mick

[George]

Mick,
It will walk when you trim bow down, otherwise, forget the tabs, keep the bow up, and she rides nicely. There is a whole new dynamic as a result of a 1,200 Lb. weight loss with the new Cats. The hull rises out of the hole very quickly because of the weight, true 700 HP, and the fact I can swing a 29" X 34" prop, where as before, 26" X 28" 3 blade was standard. She finds a level all of her own, and I have yet to run her in a serious head sea, but, in those conditions, you throttle back and probably run 25kts or less. At that point, with and 85, your well within running spec, tab down, and rip a hole in the ocean. Your hull being a 70's and I'm and 85, yours will probably have more difficulty maintaining stability due to the different design, and that's when you see owners, chopping keels, adding spray rails, putting on longer and wider tabs, etc. As far a me adding, I'm done enhancing performance as this is all I could possibly want or expect. Next is the paint job and new tower, but I have to hit the power ball lottery. To your question about PC industries, I suggest you get minimum 3-4 opinions from various repower yards. Depending where you are, you may want to touch base with Tom Slane @ Slane Marine. He is very knowledgable about Hatterases, and what you may want to do. He is very practical and pragramatic. He can consult and provide engineering services for refits. He is often on this site as well.

[mikfinf16]

Genesis,

How big a step-up gear would you use to increase engine life? Would you mind sending me you list of recommended mods?

Thanks, Mick

mikfinf16@yahoo.com

[Genesis]

If you go further, expect governor trouble. Check what's in there now - some engines already have stepped-up blower gearing, and if you go too far, you'll be unhappy as it will become impossible to balance the governor properly.

Most of the others are in this thread already.