Dennis Moore, John B, and the HP500 EFI
 

The origin of this post is John B's post entitled "mercury engineering problems!" which I have said that I would not continue to post at, as I think that his choice of "topic" or "title" is inflametory (for no reason) and not supported by the post. I did offer to continue the conversation, and I am doing that here.

In that pevious post, Mr. Moore has a displayed an apparant personal issue with either (a) Mercury Racing, (b) Mercury Engineering talent, or (c) me personally.

Mr. Moore, as a freelance jounalist, I find your verbosity entertaining, however, I find your actual knowledge to be limited. If you could put your personal issues with Mercury aside, and you give this post more consideration than a Pep Boy's counter boy, perhaps we could make some headway.

Point in fact, let us look at the information posted by "John B" that has got us to this point:

a) his HP500 EFI is running at over 5400 RPM
b) his HP500 EFI dyno'd at over 5400 RPM
c) the spark plugs in his HP500 EFI appear fouled

Mr. Moore, as a self proclaimed "expert" in the field, and as a "Mercury Master Technician" (certified when?) I am sure the you know that the rev limiter of the HP500 EFI is 5250 RPM.

I have no need to be devensive. John B posted information as fact that can not be supported as presented. As a MMT I would have thought that you would have recognized that, unless this technology post dates your certification or you and John B have an alternative agenda. I welcome additional information from John B, however to refer to Merc Eng Prob's based upon HIS info, is to refer to you as a Mercury MASTER technician. Give me a break. HT called you out on this two weeks ago; I spoke to HT...perhaps you need to reevaluate your marketing strategy.

For the record:

I am prepared to converse the pro's and con's of the HP500 EFI at your leisure. HT stands at the ready as well, awaiting your next response and hopefully, your next demonstration on Mercury envy.

You have issues...come with facts,
expect no mercy. We grow tired of rhetoric...

Who the hell is HT?

Dennis Moore,

I am staying out of this one. I'm just reading the posts to learn a few things. But, I think when Adivanman referred to "HT" he means High Tide from the other thread regarding this topic.

Guys,
The Mercury Technical Department told me two years ago that the rev limiter on the 500 efi cuts the fuel system back at 5420 and turns it back on at 5250. Is this wrong? This seems to be what I have found, but I know that analog tacks are not very accurate. Anybody?

I posted on the other sight because I didn't see this first. Sorry

HT,
Glad you could join us.

JohnB,
The has not been my experience. The HP500 EFI has a 5250 rpm ignition referenced rev limiter. I have never experienced an engine capable of exceeding that ignition based limit (and believe me I tried at Bradenton - repeatedly). 1999 based.

Formulafastech
I guess that I am the only only one who noticed that trend....

Some more info on Rev Limiter. Check out Dustin's / whipple charged post #6.

http://www.offshoreonly.com/forums/s...ev+AND+limiter

paradigm shift,
In this/that particular case, I believe that Mr. Whipple was incorrect. I can safely say that I have hit that particular limiter harder and more often than anyone you will meet. Your reference is kind of cool though...those were the days...Truckin...mini trucks, neon, and thumpin toons....must have needed a brake from his MMT duties. LOL

Troutly,
You need to find the leak...

Looks like the dyno test is not bogus after all.

Which one of you would, design a system to, cut off some of the fuel at 5200+ under max load with exhaust temperatures in the 1450's?:eureka: :frog: :crazy:

Thanks for the above information.

Anybody know about the rev limiting on the 525 EFI?

Fuel-cutting rev limiters are not certain death unless you are running a nitrous motor. Bear with me here, I'm only entering this seething cauldron cause I see a spot that needs elaboration...

Pretend that you are a single cylinder motor. You are approaching your rev limit and are running borderline lean and have some eyebrow-raising exhaust gas temps. You with me here? Okay, you have now reached your rev limit and the limiting electronics enter. The next intake stroke, the injector refuses to fire and you get no fuel on that stroke. You have only ingested air. Your spark plug still fires, but there is nothing there to light off. You complete your rotation and pump the remaining unexpanded air out the exhaust port and suck in another load of air.

At this stage, the cycle of air through the motor has produced no power and has cooled, not superheated, the internals. There has been no imminent meltdown because unlike a carb motor, there was no lean ignition. There was no ignition of charge at all - there was nothing there but air. No harm no foul. If the motor is still over the rev limit it repeats this cycle again and again until the motor is under the cut-in limit. At that point, you have a normal cycle with normal fuel and normal borderline lean operation.

No meltdown.

Add a blower. Does this change anything? Nope. Same situation.

Add nitrous. Does this change anything? Yep. Now you blow the crowns off of the pistons when the fuel injector doesn't fire and you get a load of nitrous plus just enough fuel from the spray rail to let her light, but not enough to keep her cool. Run this puppy into the rev liiter and you'll have some souveneirs. A way around it? Sure, add a rev module to stop the nitrous (and additional fuel) flow 100 rpm below the fuel cutoff. Now you got a 2-stage rev limiter. Mission accomplished.

Nothing wrong with fuel cutting rev limiters. Why would Detroit have them in ALL of their automobiles like this when it would be just as easy to add ignition cutting rev limiters???

There, I'm back to watching from the sidelines again...

Good post Mcollins!

Is the GM system to which you referred the same type of system that they are planning to use for their upcoming "displacement on demand" that will cut out cylinders when the engine is under light load? I wonder if this could ever apply to a marine environement. My guess is probably not, since a boat engine is almost always under load.

JohnB,
???

KAAMA,
I agree, I would hope that this forum could be constructive, rather that destructive. Legitimate questions and concerns can be and often are dealt with quickly and effectively.

mcollinstn,
Very well stated.

Re: I am glad someone spoke up!
 

KAAMA- Too bad you couldn't have spoke up and helped me out when Jack Baily/CESSNA/Buddah/Bobby Daniels was trying to own this board. Follow the money dude. I know how Adivanman and HT feel, but I think you and Fastech are just being vindictive because your multi name buddy got booted. Jack Bailey was not kicked off the board because of Dennis Moore, be fair at least and call Steve like I did.

According to my Mercury 500EFI service manuel, the rev limiters are set @5400.

It also shows that the motors are 509's, instead of 502". They may have just rounded up the bore from 4.47 to 4.50 though.....

I believe (might be wrong) Mercury cuts power to the electric fuel pumps to accomplish the limit.

jdnca1,
The high rev protection is through the injectors and not the pump.

By the way, my service manual does not vary from a 4.47" bore (or 4.468") - where does yours go to 4.50"? Also, where does you manual have the limiter specifications? What service manual do you have?

Thanks

mcollinstn, Good post! makes sense, good explanation! I must have been thinking carburetors---Da:crazy:

My experience with the 500 efi rev limiter was -- when rpm reached 5400+-, certain injectors shut off (I believe this is a batch fire system) and they would not fire again until the rpm was below 5250. At this point you have lost speed and the motor would again try to accelerate back to the rev limit. This could appear that the limit was 5250 if you looked at the tack. This information is from Mercury.

I would still be interested in the black spark plug issue. I just spent an hour cleaning my transom again. Do the aftermarket supercharger systems (the programming) also cause sooty transoms?

I'm glad we are back into technical talk!

What octane fuel are you running JohnB?

BT :cool:

Excellent question blue thunder. An even better question is what kind of exhaust are you running?

I'll post tonight.

Well, I try to run mine slightly rich too to keep the pistons a little cooler and to prevent the holley secondary transition from going lean, but I would think the computerized injected engines from Merc would be able to be controlled a little better than "black transoms".

Octane
 

These plugs were run with 87 octane. The first year or so of ownership I ran 89 to 93. Sometimes because of availability, I ran 93. Sooting seemed worse with higher octane.
See picture of plugs: http://www.offshoreonly.com/forums/s...threadid=59276 post #9

If the throttle position sensor signals the A/F ratio for mid-range, maybe mine are set wrong. Is this possible?

Troutly, I can understand why the would want to be rich at WOT. But they look somewhat lean, see the above post dyno test. I think they are richer in the mid range than WOT. I would like to to see some exhaust temperature data in the 3500 rpm range at 1/3 throttle and 200 hp output. I would bet the exhaust temps are under 1100 to 1200.

Warrantee claims end after one year. I don't think motors with plugs that look like mine are going to make it to 500 hours.

My 500EFI's run better on 87 than 93. Also cleaner with lower octane.

JohnB your plugs definately look fat from the other post, but I'm scratcing my head as well after looking at your EGT's.

Maybe the MR43T plugs are not ideal, too cold....??

I have a 632" in my other boat that makes 900HP on pump gas (tunnel ram) and the plugs look perfect. Didn't even have to really work at it. EGT's around 1300 on the dyno.
Run NGK plugs in this motor, the -10's were a little on the fat side and I switched to the -9's (1 step hotter) and they have the nice dark brown color. -8's were a little to scary looking to me (a trace of aluminum specs on the porcelin)

I may try to cross the MR43T's with NGK and play with the heat ranges.

The Lean / Rich Thing.....
 

Over the course of this and JohnB's previous post, there have been a couple of references to the richness of the HP500 EFI, a "sooty" transom, and blackened spark plugs. None of these are new topics to HP500 EFI owners but they are worth discussing....

The rich/lean thing...

At WOT the HP500 EFI is running slightly lean - no question. Throughout most of the camshaft powerband the HP500 EFI is running slightly (and I would argue acceptably) rich. At idle and below the camshafts powerband, the HP500 EFI seems rich when cold. This is not a shortcoming of the engine, rather it is an attempt to build a Race engine that can survive in a pleasure boating environment. The engine was not designed nor intended for extended use "off" the camshaft. No high performance or race engine - marine or automotive - carburated or injected - can be all things to every one, all the time.

The sooty transom thing...

First and foremost - soot does not equal rich by default. By definition, richness is the state in which more fuel is entering the combustion chamber than can be burnt in a single ignition event. The end result of "rich" is raw, unburnt fuel in the exhaust, a condition often associated with burning eyes, stinking exhaust, and yellow film. Soot is the end result of combustion.

Many boats with HP500 EFI's experience sooty transom conditions not due to the tuning of the engine, rather, due to the lack of tuning of the exhaust (and transom backwash). In my experience, most boats with "sooty" transoms (regardless of engine) have (a) larger "lopey" camshafts, (b) some form of switchable exhaust, and (c) exhaust in which the water mixes directly with the exhaust gases well forward of the tip - these conditions are met by most boats running with the HP500 EFI. In these circumstances soot not only freely mixes with water but does so in a relatively "slow" exhaust stream. When the exhaust gases (and liquids) exit the tail pipe, they do so only inches above the water or in aerodynamic vortex beneath the swim platform.

Is it more common at low speeds than high speeds? Yes. Lower exhaust velocity and you are not utilizing the camshaft. Is it more common with high octane than low octane? Yes. Besides octane, the different grades have different specific gravities, etc. Does the exhaust system make that big a difference? Yes. We changed from a "factory" system with Corsa Q&Q and went to a true water jacketed exhaust and have not cleaned the transom since.

I have also had the opportunity to run the HP500 EFI in a truly dry exhaust, both with and without backpressure. I can tell you without a doubt that the engine prefers no back pressure.

The spark plug thing...

Does not have to have anything to do with the first two points. It is not fair to draw conclusions (about the engine) based upon pictures of one set of plugs and no background. There are many possible factors that could and may be in play here - maintenance being first and foremost. Air Cleaner? Cap, Rotor, and Plug Wires? How old are the plugs? Who put them in and how? After maintenance is history. With a conventional ignition, generally speaking, once you severely foul a plug you will not clean it up again - ever. A service event in the past may have left fouled plugs today. Are these engines new or rebuilt? Finally there are the wildcards - operation and contamination. Simply not enough information.

Adivanman

I once inquired with Arizona Speed & Marine on their EFI setup for my 502 and they reccomended a cam with a intake lobe in the low to mid 220's @ .050 as optimum and that when you go bigger on cam timing it just start contridicting[higher RPM] the long runners on the manifold!!! This in itself is no biggie except when you consider that they are the manufacturers of the setup Merc uses on the HP500EFI!!Merc goes 230 degrees on the intake lobe...FYI

Dont shoot the messenger...just repeating what I was told.

500 EFI Cam specs;

211/[email protected] .582"lift CL not given

jdnca1,
I have to admit, you are beging to lose me here with your information. Are you sure that you are looking at HP500 EFI data?

For the record:

HP500 EFI Cam Specs:

Crane Part Number #169621.

292/298 Duration @ .004
230/236 Duration @ .050
.598"/.610" Lift
114 Lobe Center.

Adivanman;

I have Mercury Racing's service manual#6

PN 90-840283R01

GM 500 EFI Engine, Dated October 2002

On page3A-6 it shows a bore of 113.5 (4.5), however as shown further dowen the page the actual bore is 4.466. So they did round up.

On page3A-10 they show lobe lift @.020 (.342)

Duration @.050 of 211 / 227

I was surprised at cam being that short, its hard to believe....maybe book is wrong??

Still looking for rev limit info.

jdnca1, seems like I just got a Merc service bulletin correcting the book. Those numbers are not right. I'll try to remember to check at the shop tomorrow.

Bob

Adivanman,

Very through explanation, it has merit. Would this exhaust situation also cause the engine oil to turn black after 5 or 10 hours? Or would this be caused by (running off the cam)?

Maybe it is also rich somewhere. How does it run in the car? Did you try it in its stock form? This would be interesting.

What do you think the best heat range plug would be?

Also, do you have any thoughts on the spark curve? Some times I get hung right at 5000.
http://www.offshoreonly.com/forums/s...threadid=34010

Thanks, John B

Bobl;

Thanks for clearing that up;

Adivanman;

your specs are much closer to what I would have expected.

Have you found any larger cams that work well with the 500EFI? Reprogram ECU to compensate? I was thinking something like the Crane 741 and taking limiter to 5800 with lifter and valve spring change.

thx in advance.

Corey

You gotta be sh*tting me! Respond to you bunch of little old ladies sitting around tying your panties in a knot. Not likely

Formula;

I couldn't agree more with you about who I'd have work on a bone stock motor. As for high performance I'd go with Bobby Daniels, Blown 1500, etc.....and not think twice about it.

I think people forget what "high performance" entails, things WILL go wrong...its only a matter of time. Its no ones fault, componets will fail. If you can't live with that or can't afford it then stay with stock power, and maintain that or it will break too. :rolleyes: :rolleyes:

Troutly - Thank You

jdnca1 -

Obviously some changes were made in the book between 1999 (my copy) and 2002 (your copy) but that is no big deal. By the way, the cam lift referenced is not @ .020 but is cam lift +/- .020 measured at the cam (rather than at the valve).

I also think that the 741 (or 16HR) is a waste of time without heads or head work. The gain is not worth the effort on it's own. Bite the bullet and pull the heads at the same time.

formulafastech – In the interest of civility I would pass on even that option.

220BR - thanks for stopping by.

JohnB -

The issue with black engine oil in 5-10 hours has little to do with the HP500 EFI and everything to do with the environment it is run and maintained in. The biggest culprit here is the inability to completely drain the oil when changing it. If you have 10-15% dirty oil remaining, it does not take long to discolor. On the other hand, depending on the oil that you are using, color often has little or nothing to do with health or quality. Many top end synthetics (Torco for instance) are dark by nature and tend to (dis)color differently than non-synthetics.

Is the HP500 EFI rich somewhere? Yes. At 3,250 RPM cold, just as it coming up on the cam, it seems to have a burble that is barely noticeable. Get over it and you are on the cam and in the heart of the powerband. When the engine is warm it is far less noticeable and if you are under load it is a non-issue.

It runs great in the car, stock and modified. I have never had an issue with it that has given me pause. The is nothing that compares to it.

The heat range of the plug is not as cold as you would think and, in my opinion, the style of spark plug is more of a factor than the heat range in the HP500 EFI. I prefer a projected tip plug (the specific plug will vary depending on application - boat or car). In the car I run side gapped 0576 Accel's which are the same heat range as the 43T's but with a projected tip.

I have no issue with the timing curve as it comes from Mercury Racing. I have never had an issue getting past 5000 RPM except when I we are prop testing and that is my fault.

Adivanman, Thanks for the information.

I was searching some of my past experiences and remembered motors with chokes set too tight and the black smoke and soot poring out the tail pipes, boats and cars! Fuel being a hydrocarbon, when burned should form CO and CO2. If it is not all burned, because of the lack of oxygen, will convert directly to carbon in the 900+ degree temperatures, and come out the pipes.

In the combustion chamber some of this fuel will adhere to the walls and begin to do a job on the rings. Some can get into the crankcase and cause dilution and some if in the carbonized form can turn the oil black.

In my case the leak down on the center 4 cylinders is over 20%. It's leaking into the crankcase. I'm thinking that the oil on the center plugs is also caused by the blowby which enters the center of the plenum. This is on both motors.

I suspect this may not be normal. If they are fixed what should be done to get more that 175 hours next time. On the cam thing, we have no (no wake zones) here and being a cat we cruise at 60 mph+.

Yes, I am discouraged.:mad:

Mucky Transom
 

I switched my 500 EFI's to CMI pipes that divert the water to a seperate chamber exiting the motor and now don't get any mucky black crap on my transom -- I picked up appx. 1/2 MPH (I know... big deal!), and the boat sounds gooood!

If you like, give Travis Brewer at Mars Marine (281-326-6630) a call. He's a Merc Platinum Dealer, did my pipes and all the motor work on all my high performance boats.

I don't know how well you can see the pipes (headers are kind-of in the way), but attached is a photo.

Joe,

Are you saying your exhaust is totally dry now? If so and the sooty transom is gone, maybe part of the problem is as Adivanman says, the water entrains the carbon and it then splatters all over the back of the boat. Without the water being present, most of the carbon will blow away with the exhaust!

This makes more sense than water causing the engine to burn richer.:eureka:

Joe,

Our experience with the CMI exhaust was very similar, both in terms of better performance and the elimination of transom soot.

My Tunnel ram 632 has dry CMI's and NO trace of soot even after running a poker run.

Yes - to all. The transom and swim platform are always clean.

The exhaust has two thin chambers running down the external side of the exhaust pipes (that flow a small bit of water to keep the pipes cool). In the old days, this set-up also called for drilling a couple 1" holes thru the fiberglass which drained the water that originally ran thru the stock pipes. With this set-up, it's done all-in-one and still keeps the 100% stock look -- however, it now roars like a lion.

The motor is still completely stock and utilizes the water sucked up from the outdrives. Hope this clarifies things.

For a better articulation, give either CMI or Travis w/ Mars Marine (# is above) a call. Sorry, this is the best I can do (as a layman)!

In a word...NO. Displacement on demand utilizes hydraulic pressure to control activation of the valve train. By keeping the intake valve closed on various cylinders the pumping losses (lack of efficiency) under low throttle cruise are drastically decreased. When this technology is taken to the extreme, you have the new BMW745 throttleless engine. Engine speed and therefore output is totally controlled through varying valve lift and timing.