Crankcase pressure, friend or foe? How much is too much?

[Racey]

Len that is a major bummer, i know you have put a lot of time into finally getting this boat running, everything turned out so beautiful too

 

[Husqy510]

What a bummer. Hopefully the rest of the parts are fine and you can get away with a set of pistons. Do you know what the timing was set at? Is it locked out, or do you pull timing with boost?

 

[DaveH]

post up hi res pics of the spark plugs, will give an idea of what went wrong.

 

[mattyc]

its very simple actually.

not enough fuel
too much timing
poor quality fuel

or any combination of the three items listed above.

I realize that, but why? I was more so wondering if something was overlooked during dyno tune or if something went wrong with install

 

[DaveH]

I realize that, but why? I was more so wondering if something was overlooked during dyno tune or if something went wrong with install

i can think of a lot of reasons.

many have dynos that cant hold the power these engines are capable of and have to settle for a quick acceleration pass, lasting a few seconds. and while the tune might seem right under those conditions, running in a marine environment steady state, the engine may build considerable more heat then what can be simulated on the dyno.

it could be a mechanical issue, such as the manifold not flowing equally to all cylinders.

or could be a fuel starvation issue as most marine fuel systems or not up to the task of maintaining constant fuel pressure and flow.

or it could be an ignition problem, stemming from spark scatter and lighting off early.

or or or

 

[Bajastu]

The dyno has a dedicated fuel pump and regulator. This customer owned fuel pump and regulator could be the factor that created the lean condition. A test on the fuel system may be in order along with the rebuild.

 

[DaveH]

The dyno has a dedicated fuel pump and regulator. This customer owned fuel pump and regulator could be the factor that created the lean condition. A test on the fuel system may be in order along with the rebuild.

agree 200%.

but most fill the tanks, the boat sitting steady and consider the fuel system to be fine.

then throw in acceleration, turns, deceleration and you quickly discover your system ISNT fine......regardless of what the gauge says.

 

[lenmann]

Had a good conversation with engine builder this morning. Obviously he wants to see the motor and start the diagnosis so I will pull it this weekend and have it to him on Monday. He committed to a high priority in spite of a busy backlog. New piston lead times are in the 4-6 week range right now (were 16-20 this time last year) so with some luck I can get some late summer in.

I scoped all eight cylinders this morning and 4 of them have obvious damage. (# 4,6,8 and 5)

Here are pics of the plugs, I’m not an expert but they don’t look horrible to me. #6 does have a smattering of aluminum “grit” on it.

 

[lenmann]

The dyno has a dedicated fuel pump and regulator. This customer owned fuel pump and regulator could be the factor that created the lean condition. A test on the fuel system may be in order along with the rebuild.

@Bajastu what would such a fuel system test look like?

 

[lenmann]

What a bummer. Hopefully the rest of the parts are fine and you can get away with a set of pistons. Do you know what the timing was set at? Is it locked out, or do you pull timing with boost?

30 degrees total, locked out.

 

[lenmann]

Len that is a major bummer, i know you have put a lot of time into finally getting this boat running, everything turned out so beautiful too

The line from the Outlaw Josie Wales film keeps popping into my head: “Endeavor to persevere“

 

[Racey]

30 degrees total, locked out.

Crank trigger or internal distributor pickup for timing?

 

[Racey]

The dyno has a dedicated fuel pump and regulator. This customer owned fuel pump and regulator could be the factor that created the lean condition. A test on the fuel system may be in order along with the rebuild.

I would definitely be running the fuel pump and regulator that goes in the boat next time around.

 

[Bajastu]

@Bajastu what would such a fuel system test look like?

Just like what Racey said, ask your builder to use your pump and regulator on the dyno. They can measure fuel PSI, GPH, and make sure that it is keeping up with the boost pressure regulator vacuum reference port.

 

[DaveH]

you are correct that the plugs dont look horrific. but what i first noticed is the color differences are pretty dramatic, especially if these are what i suspect are low time plugs.

what heat range are the plugs, and how much boost did you max out at? what fuel are you running?

next, tell us exactly how your fuel delivery system is setup/plumbed.

finally, how much fuel was in the tanks when it went into Chernobyl?

 

[boatnam2]

What a bummer, been there done that a few times, even worse when you beg, borrow and steal to have a end game like that. Hopefully you get her back together quick and running good.

 

[obnoxious001]

I spoke to Len on the phone this morning. Let me assure all of you that he is dealing with a top notch engine builder and dyno. Len reminded me that we spoke years ago when he was getting started on this. I am sure it will get sorted out.

 

[Husqy510]

I'm sure the builder will take care of it, and it would be good to use your fuel system on the dyno in the future. On our Howard we run a FP Guage on the dash so we can monitor at WOT.

One thing I'm curious about is why so many people still run locked out distributors, when their are so many great ignitions available. On my turbo air cooled bug I run a crank trigger style ignition which gives me so much tune ability. I can retard for starting, advance at cruise, and remove timing with boost. I can also data log to verify everything is working like it should.

 

[sintax]

The dyno has a dedicated fuel pump and regulator. This customer owned fuel pump and regulator could be the factor that created the lean condition. A test on the fuel system may be in order along with the rebuild.

Came here say this!

Check your pressures and flows

 

[lenmann]

Wooo, lots of questions.

Crank trigger or internal distributor pickup for timing? No crank trigger, MSD billet distributor with internal pickup.

Data logging would be nice, especially right about now. I’ll ask the builder about possibly switching to a crank triggered set up to gain some of the benefits mentioned.

Definitely will dyno this time with the currently rigged fuel distribution set-up. I do have a fuel pressure gage on the dash, I did not see it deviate from the 7-8 lbs the regulator is set at. That said I was watching for a lot of stuff on the shakedown runs.

Current fuel distribution system: two new IMCO 35 gallon saddle tanks, 1/2 inch npt bungs, #8 lines from each tank that tee into a #8 line that feeds a Baker Engineering mechanical pump and a parallel Aeromotive electric pump that is used principally to fill the carburetor bowls at start up and then shut off. The Pumps feed a Teague fuel log and are check valved to prevent back/cross flow. #8 line up to Aeromotive four port fuel pressure regulator. #6 lines feed each bowl on two billet 1050 Dominators.

First run last fall the tanks were 1/2 full of fresh Shell 91 octane. Second run last Thursday the old fuel was drained and fresh Shell 91 octane was filled to 1/2 full.

Spark plugs: don’t know the heat range and I am out of town through Sunday. I’ll update when I get back. The plugs have the dyno runs and two hours of shake down time on them.

Boost gage showed 5-6 lbs the one and only time I got into the secondaries before I noticed the smoke pouring from the breathers.

 

[Husqy510]

I appreciate you sharing your story, as we all learn from posts like these and the knowledgeable people that contribute. Most of us that have been into hotrods and performance boats for a while have had similar experiences. Some lessons are learned the hard way, and some are learned from posts like this.

Sounds like you have a pretty stout fuel system, but I'm sure that will be verified on the dyno. The last motor I had dynoed was simply broken in and ran for max HP. On a turbo deal, I'm sure it's more important to tune across the rpm range and load level to insure it doesn't go lean at partial throttle. My little turbo motor spools up pretty quick so it's important that the EFI adds an appropriate amount of fuel when the boost kicks in at partial throttle.

Good luck and thanks for sharing the details

 

[Dcb.blake]

Boy those plugs look not too bad from the pics hard to argue with that. If you’re a critic you could say they look a little skinny but no way enough to smoke a piston like that.

The biggest thing with the fuel is make sure you’re not getting any aeration with the fuel imo. That could cause a lot of issues. Make sure everything is plenty tight and the pump is more than you need, it will just go back to tank and no issues in a properly plumbed system.

Watch the flow not psi.


Just read everything a bit more. Sounds like you have a great builder that’s as curious as you are which is gold now days.

Long shot but the plugs were too hot and burned too fast??

Hope you get to the bottom of it

 

[mattyc]

Wooo, lots of questions.

Crank trigger or internal distributor pickup for timing? No crank trigger, MSD billet distributor with internal pickup.

Data logging would be nice, especially right about now. I’ll ask the builder about possibly switching to a crank triggered set up to gain some of the benefits mentioned.

Definitely will dyno this time with the currently rigged fuel distribution set-up. I do have a fuel pressure gage on the dash, I did not see it deviate from the 7-8 lbs the regulator is set at. That said I was watching for a lot of stuff on the shakedown runs.

Current fuel distribution system: two new IMCO 35 gallon saddle tanks, 1/2 inch npt bungs, #8 lines from each tank that tee into a #8 line that feeds a Baker Engineering mechanical pump and a parallel Aeromotive electric pump that is used principally to fill the carburetor bowls at start up and then shut off. The Pumps feed a Teague fuel log and are check valved to prevent back/cross flow. #8 line up to Aeromotive four port fuel pressure regulator. #6 lines feed each bowl on two billet 1050 Dominators.

First run last fall the tanks were 1/2 full of fresh Shell 91 octane. Second run last Thursday the old fuel was drained and fresh Shell 91 octane was filled to 1/2 full.

Spark plugs: don’t know the heat range and I am out of town through Sunday. I’ll update when I get back. The plugs have the dyno runs and two hours of shake down time on them.

Boost gage showed 5-6 lbs the one and only time I got into the secondaries before I noticed the smoke pouring from the breathers.

Where are you taking your fuel pressure reading from? Mechanical gauge?

 

[lenmann]

Where are you taking your fuel pressure reading from? Mechanical gauge?

Two gages. The dash mounted gage is fed by an electric sender on the fuel pressure regulator. The second gage, which is mechanical, is on the fuel log that the two pumps feed reading non-pressure regulated fuel.

 

[DaveH]

from the pics, those plugs are not too hot. when the plug is too hot, the strap will glow red hot burning any carbon off it.

i would bet this was caused by poor fuel delivery. there is no way you will have steady unaerated fuel delivery with the setup you described.

 

[rivermobster]

I spoke to Len on the phone this morning. Let me assure all of you that he is dealing with a top notch engine builder and dyno. Len reminded me that we spoke years ago when he was getting started on this. I am sure it will get sorted out.

Terrible news on the engine.

This is promising though.

We killed an engine on my BIL's boat due to fuel supply issues. This stuff is hard on the wallet.

 

[DaveH]

Wooo, lots of questions.

Crank trigger or internal distributor pickup for timing? No crank trigger, MSD billet distributor with internal pickup.

Data logging would be nice, especially right about now. I’ll ask the builder about possibly switching to a crank triggered set up to gain some of the benefits mentioned.

Definitely will dyno this time with the currently rigged fuel distribution set-up. I do have a fuel pressure gage on the dash, I did not see it deviate from the 7-8 lbs the regulator is set at. That said I was watching for a lot of stuff on the shakedown runs.

Current fuel distribution system: two new IMCO 35 gallon saddle tanks, 1/2 inch npt bungs, #8 lines from each tank that tee into a #8 line that feeds a Baker Engineering mechanical pump and a parallel Aeromotive electric pump that is used principally to fill the carburetor bowls at start up and then shut off. The Pumps feed a Teague fuel log and are check valved to prevent back/cross flow. #8 line up to Aeromotive four port fuel pressure regulator. #6 lines feed each bowl on two billet 1050 Dominators.

First run last fall the tanks were 1/2 full of fresh Shell 91 octane. Second run last Thursday the old fuel was drained and fresh Shell 91 octane was filled to 1/2 full.

Spark plugs: don’t know the heat range and I am out of town through Sunday. I’ll update when I get back. The plugs have the dyno runs and two hours of shake down time on them.

Boost gage showed 5-6 lbs the one and only time I got into the secondaries before I noticed the smoke pouring from the breathers.

here is your data logging setup

L120 Enclosed Logger-M L120-RETAIL

supports 6 3 wire sensors (fluid pressure, manifold pressure, throttle position etc) and 2 two wire temp temp sensors (engine coolant temp, manifold air temp etc) and would allow yout to interface multiple exhaust wide band sensors or even 8 EGT's with the use of CAN interfaces. also support a GPS antenna for logging of vessel speed.

 

[lenmann]

from the pics, those plugs are not too hot. when the plug is too hot, the strap will glow red hot burning any carbon off it.

i would bet this was caused by poor fuel delivery. there is no way you will have steady unaerated fuel delivery with the setup you described.

Can you walk me through your thinking here? In other words what’s wrong with it and how should it be set up? Really just trying to learn.

 

[DaveH]

Can you walk me through your thinking here? In other words what’s wrong with it and how should it be set up? Really just trying to learn.

the problem is the fuel tank.

ive yet to ever see a marine tank that has proper baffling in it. the more you accelerate, decelerate, turn, the G forces.....the fuel becomes violently "washing machined" and completely aeriated. this wont be visible to a pressure gauge as air is compressible and dumb gauges cant tell the difference between air and fuel or a mix of the two. keeping the tanks FULL lessens the issue but it is there nonetheless.

you need a vapor separator tank with feeder pumps to fix this. Kinsler EFI makes them and the associated components to go with it, or they can be custom made your specific application. seen many turbo motors melt down over this very issue.

Vapor Separator Tank: 4" diameter x 12" tall, blue anodized aluminum - Kinsler Fuel Injection

Note : Image Shown is of 3" Diameter Tank

kinsler.com

 

[BamBam]

the problem is the fuel tank.

ive yet to ever see a marine tank that has proper baffling in it. the more you accelerate, decelerate, turn, the G forces.....the fuel becomes violently "washing machined" and completely aeriated. this wont be visible to a pressure gauge as air is compressible and dumb gauges cant tell the difference between air and fuel or a mix of the two. keeping the tanks FULL lessens the issue but it is there nonetheless.

you need a vapor separator tank with feeder pumps to fix this. Kinsler EFI makes them and the associated components to go with it, or they can be custom made your specific application. seen many turbo motors melt down over this very issue.

Vapor Separator Tank: 4" diameter x 12" tall, blue anodized aluminum - Kinsler Fuel Injection

Note : Image Shown is of 3" Diameter Tank

kinsler.com

I completely understand this concept in an EFI set-up. I have run a pressurized secondary tank on my EFI set-up from day one. I pump to it from the saddle tanks with low pressure pumps and feed the high pressure fuel pump from the secondary tank. However, I don't understand how this is that critical on a dual carb setup. Obviously air is bad but there is: 1) a reserve of fuel in the float bowls and 2) an escape for the air in the float bowls before the fuel enters the engine. Neither of those are present on a EFI.
I am not challenging your theory, I'm trying to wrap my head around it.

 

[motormonkey]

My opinion. Is low octane gas. I've seen this before.
Any boosted setup I always recommend tipping in a pail or just straight race gas.

 

[DaveH]

I completely understand this concept in an EFI set-up. I have run a pressurized secondary tank on my EFI set-up from day one. I pump to it from the saddle tanks with low pressure pumps and feed the high pressure fuel pump from the secondary tank. However, I don't understand how this is that critical on a dual carb setup. Obviously air is bad but there is: 1) a reserve of fuel in the float bowls and 2) an escape for the air in the float bowls before the fuel enters the engine. Neither of those are present on a EFI.
I am not challenging your theory, I'm trying to wrap my head around it.

you are correct the need for stable fuel delivery is even more import with EFI then compared to a carb.

but a float bowl is a poor substitute for delivery of unaerated fuel. think of the volume and flow of fuel required to make 1000hp and the tiny size of the float bowls.

then the timeless old saying of "well i had a forced induction engine setup this way 20 years ago and it worked fine" comes to mind. well, the engines of yesterday arent making anywhere near the power levels of today due to better parts and everyone wants to do it on cheap gas now. but to to run at these power levels with low quality fuel, requires VERY accurate not just fuel but spark delivery as well. and this is very difficult to achieve with an entirely mechanical setup.

 

[Racey]

Many factors we don't know here.

Was it, windy? rough?

What was the fuel level in tanks?

Where from, what type, and how old was the gas used?

What type of ignition system? MSD? verified the magnetic pickup polarity is correct?

Float levels high enough in the carbs?

When you dyno'd the motors did you do prolonged runs at constant RPMs under partial throttle conditions? verifying the power valve setup is working correctly.
(Remember on draw throughs the carb can still be in high vacuum even though post turbo and intercooler you are in boost)

Partial throttle runs right up to the point of the secondaries? then into the secondaries?



Just throwing out a lot of questions that should be considered and either eliminated or addressed.

 

[SMPLV]

the problem is the fuel tank.

ive yet to ever see a marine tank that has proper baffling in it. the more you accelerate, decelerate, turn, the G forces.....the fuel becomes violently "washing machined" and completely aeriated. this wont be visible to a pressure gauge as air is compressible and dumb gauges cant tell the difference between air and fuel or a mix of the two. keeping the tanks FULL lessens the issue but it is there nonetheless.

you need a vapor separator tank with feeder pumps to fix this. Kinsler EFI makes them and the associated components to go with it, or they can be custom made your specific application. seen many turbo motors melt down over this very issue.

Vapor Separator Tank: 4" diameter x 12" tall, blue anodized aluminum - Kinsler Fuel Injection

Note : Image Shown is of 3" Diameter Tank

kinsler.com

This sounds very familiar haha

 

[Teague_JR]

Sorry to see you’re having problems. A few thoughts.

You can’t read the plugs at this point. The rings are already smoked so the plugs are only useful enough to show you the piston bits glittered on them.

Your fuel system seems more than adequate. You would have to notice a pressure drop (or volume deficiency for the fluid scientists here) for a decent period of time at higher RPM to do that kind of damage. As soon as you roll it into boost pressure would creep down and continue to creep down.

1050 dominators are a lot of carburetor for a 975 hp turbo motor. We did a 1300 hp gentry/turbonetics motor with 830 annular no problem. What’s your compression to make 975 at only 6-7 psi boost?

I think you are critically lean somewhere with your carb setup. Perhaps the top of the primaries. Perhaps everywhere. It’s hard to believe a short burst at 5000 rpm would cause that kind of piston damage. If you aren’t replicating a proven carburetor setup, you NEED to run the engine in the boat at all throttle application levels with a wide band air fuel meter. WOT dyno pulls are useful for getting in the ballpark but are not representative of having the motor dialed in running in the boat. It needs to be richer than a lot of drag race tooners think…

Good luck JT

 

[lenmann]

More great insights and questions. I am scrambling a little bit right now pulling the engine to get it back to the builder before we head to the lake for the 4th.

I will respond to the questions once the smoke clears (hah!). The responses on this thread have definitely expanded my understanding which is great, thank you all.

 

[obnoxious001]

1050 dominators are a lot of carburetor for a 975 hp turbo motor. We did a 1300 hp gentry/turbonetics motor with 830 annular no problem. What’s your compression to make 975 at only 6-7 psi boost?

I think you are critically lean somewhere with your carb setup. Perhaps the top of the primaries. Perhaps everywhere. It’s hard to believe a short burst at 5000 rpm would cause that kind of piston damage. If you aren’t replicating a proven carburetor setup, you NEED to run the engine in the boat at all throttle application levels with a wide band air fuel meter. WOT dyno pulls are useful for getting in the ballpark but are not representative of having the motor dialed in running in the boat. It needs to be richer than a lot of drag race tooners think…

Good luck JT

I spoke to him on the phone the other day and mentioned that only a couple of guys tried Dominators on ski race boats and didn't get good results, that the 830 was the carb of choice for that type system.

I had a chance to see the dyno sheets and no cylinder temperature readings, no AF readings or even boost readings that I recall. Perhaps he had some stand alone metering for those, I have seen it at other dynos.

 

[lenmann]

Not how I wanted to spend the Monday before the 4th.

A couple of take aways from the owner of the shop that built the motor:

A/F ratio, exhaust temp, and boost were monitored independently back when the engine was built (2017) and would have been a part of any dyno run they performed.

He said standard protocol would have been to run the engine at all RPM ranges to assure jetting was correct through out the intended operating range of the motor.

The tech that assembled and dyno tested the motor isn't with the company any longer but they will search back through their paper and digital records to learn anything they can. They have since installed a new dyno so the original dyno runs are on an old hard drive that may or may not yield results.

They will tear it down this week and report back.

He recommended that the turbos go to Carson for evaluation and/or rebuild.

Current lead time for new pistons is 4-6 weeks.

He is committed to turning it as fast as he can, this was not the way he wanted to see me again. Overall very happy with his approach so far.

 

[BamBam]

Not how I wanted to spend the Monday before the 4th.

View attachment 1246350

A couple of take aways from the owner of the shop that built the motor:

A/F ratio, exhaust temp, and boost were monitored independently back when the engine was built (2017) and would have been a part of any dyno run they performed.

He said standard protocol would have been to run the engine at all RPM ranges to assure jetting was correct through out the intended operating range of the motor.

The tech that assembled and dyno tested the motor isn't with the company any longer but they will search back through their paper and digital records to learn anything they can. They have since installed a new dyno so the original dyno runs are on an old hard drive that may or may not yield results.

They will tear it down this week and report back.

He recommended that the turbos go to Carson for evaluation and/or rebuild.

Current lead time for new pistons is 4-6 weeks.

He is committed to turning it as fast as he can, this was not the way he wanted to see me again. Overall very happy with his approach so far.

Hope it gets fixed and back in the boat quickly. Sorry you had to do all this work. You are a true craftsman who built an incredibly nice boat. The next chapter will end better.

 

[rivermobster]

Hope it gets fixed and back in the boat quickly. Sorry you had to do all this work. You are a true craftsman who built an incredibly nice boat. The next chapter will end better.

X2

 

[mattyc]

Not how I wanted to spend the Monday before the 4th.

View attachment 1246350

A couple of take aways from the owner of the shop that built the motor:

A/F ratio, exhaust temp, and boost were monitored independently back when the engine was built (2017) and would have been a part of any dyno run they performed.

He said standard protocol would have been to run the engine at all RPM ranges to assure jetting was correct through out the intended operating range of the motor.

The tech that assembled and dyno tested the motor isn't with the company any longer but they will search back through their paper and digital records to learn anything they can. They have since installed a new dyno so the original dyno runs are on an old hard drive that may or may not yield results.

They will tear it down this week and report back.

He recommended that the turbos go to Carson for evaluation and/or rebuild.

Current lead time for new pistons is 4-6 weeks.

He is committed to turning it as fast as he can, this was not the way he wanted to see me again. Overall very happy with his approach so far.

Glad you're moving forward on it quickly. Very interested in finding out what you learn.

Is that your place in the picture?

 

[lenmann]

Glad you're moving forward on it quickly. Very interested in finding out what you learn.

Is that your place in the picture?

Hoping the summer is a long one this year, might still get some time in the boat if the stars all align. My plan is to share what we find, maybe it will help some other lunk like me someday.

The shop in the pics is mine. When I retired we built a home in Shasta County, CA. Well more accurately my wife got her dream home and I got my dream shop. I have built and repaired plenty of cars and boats in driveways and side yards, the shop is a lot better.

 

[Wheeler]

Hoping the summer is a long one this year, might still get some time in the boat if the stars all align. My plan is to share what we find, maybe it will help some other lunk like me someday.

The shop in the pics is mine. When I retired we built a home in Shasta County, CA. Well more accurately my wife got her dream home and I got my dream shop. I have built and repaired plenty of cars and boats in driveways and side yards, the shop is a lot better.

Your gantry is bitchen! the rest of the shop is ok too.

 

[ChrisV]

Does any boat people put air fuel gauge on? One of the most important gauge imo.

 

[Husqy510]

Does any boat people put air fuel gauge on? One of the most important gauge imo.

I think it's a challenge with wet exhaust and/or short tailpipes where the o2 sensor is too close to fresh air.

 

[BamBam]

I think it's a challenge with wet exhaust and/or short tailpipes where the o2 sensor is too close to fresh air.

He had Imco place bungs into the exhaust near the turbo. they go through the water jacket.

 

[rivermobster]

He had Imco place bungs into the exhaust near the turbo. they go through the water jacket.

We had CMI do that on my buddies Stoker as well.

 

[Teague_JR]

Does any boat people put air fuel gauge on? One of the most important gauge imo.

Running them full time could be a pain in the ass because the moisture in marine environment kills sensors, especially in super high performance that are on the edge of reversion etc…

I would highly recommend installing bungs into every header or tail near the header/tail flange, then you can throw a gauge setup on it for testing purposes easily

JT

 

[BamBam]

@lenmann Where do you stand on this? Sorry you missed the whole summer. Keep us posted on any progress.

 

[ChrisV]

Hey @lenmann, hows the boat?