Melted pistons

[Unchained]

Well in my neverending greed to get the most HP out of my engine on pump gas I ended up melting the edges of a couple pistons. No real biggie as they had 7 seasons on them and I ran it hard during that time. The original BME pistons had over 200 hours on them. I just would have preferred to do this in the off season. I believe my A/F was good but I had too much total timing in it. Don't ask.
I've got to say that the hp that it was producing on pump gas and 11# boost was just awesome, even with one dead cylinder and a few more lazy ones.
Some research confirmed that there is actually more energy in lower octane fuels. High octane fuels just burn slower and have more resistance to detonation. There is a fine line between the max hp and melting pistons.
I will have to detune it more and probably run a water/alky inj. unit now.
I hate the word "detune" :(
I'm reassembling now with new pistons, rings, bearings, etc. I'll be back on the water in three or four days.
As it turned out it's good that I tore it down because the mount on my new Milodon oil pickup tube was already broke. There's always something ready to break. :idea:
You can see some smoke coming out the pipes in this short video that Flattie took 2 weeks ago,
http://s93.photobucket.com/albums/l65/rixalot/?action=view&current=M2U00333.flv
This v drive tunnel hull airs out immediately even with the weight of two of us in the boat. Looking back I intended on babying this for a while until I got the tune perfect and got used to the hull more. When I found out what a monster it was ....................... adrenaline took over.

[Fiat48]

Man that leaves hard! :D

[ghittner]

Sorry man, I'm doing the EXACT same thing now.... Right in the middle of the season. Too much timing as well, it is a fine line isn't it? I just had to see if 36 Deg would be better than 30 where all was working well. Well, that 15 second burst cost me 4 piston edges right where that stinkin Chev valve relief lies. And no more power. A lesson here to remain conservative on ones timing...GRRRRHHHHH., like you a total rebuild. Just a chance to make it faster!!! Scramblin' now!

[Craig]

Nice video, timing sucks :( I'm hoping to make it to the fall before I have to do mine. :D I've got 6 good seasons on it.

[Kyote]

Nice video, timing sucks :( I'm hoping to make it to the fall before I have to do mine. :D I've got 6 good seasons on it.
Hope that you remain Lucky. I melted #7 piston, broke a ring and as the pieces exited they took all of the blades on the turbo exhaust wheel with them. Engine rebuild and a new turbo. Expensive lesson. No more 17lbs of boost!

[Morg]

Mark,
Boat looks & sounds great.
Hope you get her back on the water soon.

[Unchained]

Thanks for the positive feedback.
I considered not airing my dirty laundry but then thought maybe someone else can learn from my mistakes. Besides that I'm not one to put on airs.
The pistons that I roasted were all in the same place just like ghittner said.
Right at the edge of the intake valve relief on the head of the piston.
Funny thing was other pistons showed no signs of problems at all and the rings looked good too. I expected to see pick marks in the head of the pistons if there had been detonation but there was none of that. There were signs of aluminum raising up like it had turned to butter for an instant.

[sanger rat]

So what did you end up finding for new pistons?

[ghittner]

Thanks for the positive feedback.
I considered not airing my dirty laundry but then thought maybe someone else can learn from my mistakes. Besides that I'm not one to put on airs.
The pistons that I roasted were all in the same place just like ghittner said.
Right at the edge of the intake valve relief on the head of the piston.
Funny thing was other pistons showed no signs of problems at all and the rings looked good too. I expected to see pick marks in the head of the pistons if there had been detonation but there was none of that. There were signs of aluminum raising up like it had turned to butter for an instant.
Sre you sure we didn't tear down the same motor???? :sqeyes: I'm runnin' the SRP's again with less compression this time 8:1 instead of 9. Pump gas here....

[Unchained]

I ended up with J & E flat tops that will give me 8:1 compression ratio.
I had 7.5:1 before.
I got 4.530" diameter and the top of the wrist pin is about even with the top of the oil ring pack. These pistons have a lot shorter skirt than the BME pistons had. I have 7.25" long rods and a 10.7" tall deck Arias block.

[llepd]

I ended up with J & E flat tops that will give me 8:1 compression ratio.
I had 7.5:1 before.
I got 4.530" diameter and the top of the wrist pin is about even with the top of the oil ring pack. These pistons have a lot shorter skirt than the BME pistons had. I have 7.25" long rods and a 10.7" tall deck Arias block.
Sorry to hear about your boat heard about it on the river this weekend. I think I finaly got mine figured out, weekend anf parked in garage still running.
Dale

[Unchained]

No worries Dale.
You know first hand why I never looked at the gauges on this boat while I had my foot in it. :D
I still don't know what RPM I was turning or what the exact boost was. It was that white knuckle problem. :jawdrop:
I have a datalogger, I'll be using that again next time.
OK Dale, It took me a while but I just figured out that user name. LOL

[Infomaniac]

Man that leaves hard! :D
LOL
I've had mine get up on the prop and walk the back end around.

[Itsahobby]

Well, this kind of laundry is good for guys like me. I was just think of pushing up my timing. Now you got me thinking. My boat is just a Family V-drive and with my engine setup, I ain't gonna gain much by stepping up the timing.
Thanks for the post.
Jerry
Thanks for the positive feedback.
I considered not airing my dirty laundry but then thought maybe someone else can learn from my mistakes. Besides that I'm not one to put on airs.
The pistons that I roasted were all in the same place just like ghittner said.
Right at the edge of the intake valve relief on the head of the piston.
Funny thing was other pistons showed no signs of problems at all and the rings looked good too. I expected to see pick marks in the head of the pistons if there had been detonation but there was none of that. There were signs of aluminum raising up like it had turned to butter for an instant.

[84 cougar]

Info, I also have a 19 cougar v drive. Just wondering why we havent seen or heard much about yours lately???? Still tunnel ram??, or did you go back???

[ghittner]

Well, this kind of laundry is good for guys like me. I was just think of pushing up my timing. Now you got me thinking. My boat is just a Family V-drive and with my engine setup, I ain't gonna gain much by stepping up the timing.
Thanks for the post.
Jerry
I moved mine from 30 to 36 degrees and it took 15 seconds to waste four pistons. And for the 15 seconds I could tell absolutely no difference in power..... Just for your info.

[DEL51]

Mark, don't feel too bad, it could have been worse.I have low oil pressure and dodged a bullet by pulling out the oil pump. The bypass pressure spring broke. Caught it early enough. What kind of water/meth injection system are you considering?

[Unchained]

That Snow unit looks like a good one.
I read an article about it in Turbo and hi-tech performance mag.
They claim a small increase in hp from it but it requires leaning out your fuel map and adding back timing to compensate for the alcohol. That makes it an integral part and I don't like that about it. Any water inj. failure and the engine would for sure be toast.
It cost $ 1.50 more per gallon for 110 octane than 93 octane and I never had a problem with that fuel. It's just real inconvenient at the stations around here.

[N281PONY]

Have you guys tryed the new E-85 pump gas. I have heard several guys with turbo cars picking up a little power. The neat thing about the Snow Injection System is it uses good ole washer fluid (for once the cheaper is better).

[Sleeper CP]

I moved mine from 30 to 36 degrees and it took 15 seconds to waste four pistons. And for the 15 seconds I could tell absolutely no difference in power..... Just for your info.
Just asking" 30 to 36 degrees" with how much boost? And did you bump your water/alcohol injection when you did it?
Sleeper CP

[Unchained]

I also have a 19 cougar v drive.
Put up some pics and stats of your boat.

[ghittner]

Just asking" 30 to 36 degrees" with how much boost? And did you bump your water/alcohol injection when you did it?
Sleeper CP
I'm blown, no turboed like unchained. Booost is boost and timing is timing however.
Pump gas, 9:1 static compression, blower 8 pds boost, dual 750 carbs jetted properly.
I will run 8:1 static this time 32 degrees timing all else the same...

[Sleeper CP]

.
Pump gas, 9:1 static compression, blower 8 pds boost, dual 750 carbs jetted properly.
I will run 8:1 static this time 32 degrees timing all else the same...
You did that on pump gas. That was a roll of the dice.:( Lesson learned , the hard way:mad: :eek:
Don' think your static compression was the problem or the boost just to much timming. Just courious, do you know how big the windows are in your needle and seats?
Had a friend that burned his blower motor down twice before he figured out that his carbs had .080 windows in the needle and seats. He put .110 or .120 in and problem went away.
Sleeper CP

[ghittner]

Holley 750 DP's

[Unchained]

I was at 33 degrees total timing at 11# boost and that proved to be too much. Since I got this going this spring I don't think I've had it WOT for more than 4 or 5 seconds and that was enough to melt the pistons.
I'm thinking that 93 octane needs to be a total timing of 30 degrees or less with my engine at WOT. Maybe this long rod setup needs less timing.
I've got the rebuild completed and am ready to fire up now. After some break in time I'll datalog and double check my A/F ratios from scratch.

[ghittner]

I wish I was as fast at buildin' as you!!!! Let us know what's up when you run it. How many pds boost are planning on runnin'? Thanks.

[paradigm shift]

All this sounds all to familliar. :mad: I got lucky only got the pistons, cylinders - block were fine. I blamed it on bad gas from the Delta last year.
http://www.***boat.com/image_center/data/522/2077Piston_ouch.jpg

[Unchained]

I got it fired back up today and it runs like a brand new piece again.
The engine shop owner told me that about 8# boost is the most that is going to run on pump premium regardless of the timing and the a/f ratio. The least I have been able to get those big turbos down to is 11#. I'm going to have to go back to 110 octane until I can get a water/alky inj unit for it to make it run pump gas.

[Kyote]

All this sounds all to familliar. :mad: I got lucky only got the pistons, cylinders - block were fine. I blamed it on bad gas from the Delta last year.
http://www.***boat.com/image_center/data/522/2077Piston_ouch.jpg
If you had stayed on it nano seconds longer you would have busted that exposed ring and there goes a turbo. Lucky you.

[ghittner]

I got it fired back up today and it runs like a brand new piece again.
The engine shop owner told me that about 8# boost is the most that is going to run on pump premium regardless of the timing and the a/f ratio. The least I have been able to get those big turbos down to is 11#. I'm going to have to go back to 110 octane until I can get a water/alky inj unit for it to make it run pump gas.
Congrats!

[Gearhead]

Unchained,
I'm glad you have your ride back together! And with the power potential of your mill, I am happy to hear you will be putting some better fuel in the boat.
We have a number of performance enthusiast in this area that also try to run pump gas, but there is a limit to how much power (boost/compression/cylinder pressure) that can be run over a period of time without engine damage.
I like to build engine probably more than the next guy, but I don't like pulling them down for no particular reason or for something that I can prevent. Over the years I have come to a belief that good fuel is one of the lower cost of running and operating a performance mill. In other words, I believe it is cheaper to purchase good fuel rather than having to repair a damaged engine.
The performance fuels have many advantages. The lead definately helps octane as well as coat the valve seats and guides for longer life. Limiting or preventing detonation not only helps piston and ring life, but also helps from beating the bearings to death. At the same time, one needs only as much octane as they need. Too high of an octane can actually slow down the combustion burn too much.
Glad your back on the water! Keep us posted with your performance progress.

[Unchained]

Unchained,
I like to build engine probably more than the next guy, but I don't like pulling them down for no particular reason or for something that I can prevent.
I agree to that. I also told myself long ago that when you ask an engine to produce two or three times what it was supposed to by pumping the boost to it you have to be ready to repair or replace it at any time.
Even though I ended up makeing a major repair I feel successful that I thrashed it for 7 seasons prior to this. I learn a little more every time.

[Fiat48]

When you hurt it.....did it "flash" (melt) the ground strap on the spark plugs on those cylinders that hurt pistons?
What number cylinders hurt the pistons.....and which ones didn't?

[Unchained]

When you hurt it.....did it "flash" (melt) the ground strap on the spark plugs on those cylinders that hurt pistons?
What number cylinders hurt the pistons.....and which ones didn't?
The plugs were fine, I cleaned them, put them back in and used them again.
The ground straps had a yellow tint to them.
The worst pistons were # 5 and # 8 I don't exactly remember the numbers of the other two.
The two worst pistons had material gone from the weak spot next to the valve relief. On the two other bad ones the aluminum got soft and raised up from the top of the ring land to the crown and rehardened. I would speculate that the worst ones got real hot in that spot and the aluminum turned soft and raised up at the top of the stroke and then chunks broke off.

[Fiat48]

Thanks. And may I ask what brand and heat range plug you are running?

[Unchained]

I'm running NGK V power, 9 heat range I don't have all the numbers handy.
I think these plugs are a little cold if anything.

[Warp Speed]

I'm running NGK V power, 9 heat range I don't have all the numbers handy.
I think these plugs are a little cold if anything.
I can't imagine anything being too cold for the power you must be making with that thing!!
What kind of ignition (mag/crank trigger ect..) are you running?
Warp Speed

[Unchained]

I'm running a crank trigger with a hall effect sensor. That signal goes to the Haltech ECU which fires the MSD 7 box. It has been a good reliable setup.

[Marty Gras]

EGT's numbers durring melt down? How do the valves, seats and guides look? What about "fuel cooling", between the pump and the injectors and then on the return trip too? (ice filled can?) I like the "cooling effect" of water injection in small doses. It cools the intake runners (if done up stream) and it's "steam cooling effect" is nice and safe in the cylinders. (takes up little room) I don't like the idea of a water and alcohol (unknown burn rate) taking up valuable volume in the cylinders. If you must inject, won't the Haltech control the "added system"? (TPI?, boost?, temp?) Do you have a method to test the fuels you are using? Please remember this is not a car, the vibration, pounding, and moisture can "test" the best electronic car parts.

[Warp Speed]

Sound like all your systems are top notch.
About the only way to make it a little more durable (without losing a bunch of boost), is to take .250 or so out of that rod length and put it into some piston material (what stroke you running?). With all the pressure you are making, I doubt you would notice much loss in power from moving that top ring down some. And it would make it allot tougher in that area (may still just be masking another problem, but it doesn't sound like you are new to the turbo deal). The short compression height you are running is great for normaly aspirated, but I would imagine it being borderline with lots of pressure or spray. How do the top of the rods look?? Unless you are running that thing 10,000 rpm, or have a 5+inch stroke, losing a little rod length isn't going to hurt things and should toughen those pistons up a bunch.
Also, if you are a little over ratio'd on the rod lenght, I would imagine the increased dwell time at TDC would be less forgiving with all that pressure.
You also noted that the new pistons have less skirt than the old ones. Keep in mind, when you lessen skirt area and ring size, you are taking away heat path. Especialy running the ring that close to the top of the piston.
Piston oilers would help also, but that is another story all together.
I am definatly not saying you are doing things wrong. Hell, I have never built a turbo engine. So all I can do is look at the systems I am familier with. I would love to hear some feedback on my observations from some of the turbo guru's, as the stuff is very interesting but foreign to me.
The way I look at it is cumbustion heat is cumbustion heat. If ignition and fuel systems are properly set and monitored, an overall look at short block combo may help durability with minimal, if any performance loss.
Warp Speed

[cfm]

Warp speed - very good thoughts !!! Just because a piston is "forged" and provides acceptable compression ratios does not mean it is a "blower/turbo" piston.
There are various forged piston materials and of course ring heights, thicknesses, etc,etc,etc,etc.
===============
Piston oilers for SBC/BBC are now made by Bolaws. A handful of offshore teams with big SC / Turbocharged engine's use these (piston oilers) to keep temps down.
http://www.blp.com/

[superdave013]

alot pf people would be happy making that kind of power for 7 months.
Congrats on the 7 years. lol

[Unchained]

Mardi gras and Warp speed. Thanks for those thoughts.
I agree on the water injection George. I ran that setup years ago when I raced at the sand drags with a high boost turbo honda and it worked well but I am reluctant to add something that requires changing the tune totally.
I also questioned if my long rod setup made the pistons dwell at tdc longer and made them more succeptable to meltdown. I've got 7.25 " rods and a 10.7 " deck on this motor. The top ring is not all that close to the head of the piston on these J & E's I don't believe that is a weak link. These pistons were supposed to be good for turbos or nitrous.

[Warp Speed]

Piston oilers for SBC/BBC are now made by Bolaws. A handful of offshore teams with big SC / Turbocharged engine's use these (piston oilers) to keep temps down.
http://www.blp.com/
That sure wouldn't hurt things!!!!! ;)

[Warp Speed]

Mardi gras and Warp speed. Thanks for those thoughts.
I agree on the water injection George. I ran that setup years ago when I raced at the sand drags with a high boost turbo honda and it worked well but I am reluctant to add something that requires changing the tune totally.
I also questioned if my long rod setup made the pistons dwell at tdc longer and made them more succeptable to meltdown. I've got 7.25 " rods and a 10.7 " deck on this motor. The top ring is not all that close to the head of the piston on these J & E's I don't believe that is a weak link. These pistons were supposed to be good for turbos or nitrous.
What stroke are you running with those rods?

[Unchained]

It's a 4.25" stroke and a 4.530 " bore

[Warp Speed]

It's a 4.25" stroke and a 4.530 " bore
Well, with a true (excact) 10.7 deck and .005-? in the hole, that leaves you with around a 1.32 compression heigth. Assuming a .990 pin, that gives us what I would think to be a pretty tight ring package for that kind of beast. I would guess for that application it would help durability a bunch if they where more spread out and as far away from the crown and valve pocket as reasonably possible. That dwell at tdc with all that boost may not be helping either!
But now that I think about it for a minute, you have been running this combo for 7 years with out a failure. I say you go boy!!! You can't be doing much wrong!!
That thing has to be a blast!!
If you can feed them, those piston oilers would be a nice addition!

[Unchained]

The top of the wrist pin is even with the top of the oil ring so the rings look spread out pretty good to me. The BME pistons I had originally were really top notch but they jumped the price on those up to 1200. + a set from the 800. I originally paid. The J & Es were just under 800. and they were on the shelf. I wish that on HP parts there could be some consistency in pricing.

[WETTE VETTE]

Mark,
Check out some of the heat shield coatings that are out there for pistons these days. Some pretty impressive claims are being made on the heat rejection rate these coatings provide. Also do you think the v-drive is loading your motor more than the jet drive you have previously run and that could be part of the problem? I remember seeing an onboard vid of the jet and from the word go RPM's were 7000 and the boat caught up. If the v-drive loads the motor harder it could be causing some mid RPM detonation. Just a thought.
Craig

[Unchained]

I had intended on going with the coating on the head of the piston but getting it back together right away was more important.
With some of the runs I've made with this boat around here and locals I've taken for rides people are buzzing about it. Everywhere I go I get asked for a thrill ride now. This boat pulls so hard that a real good thrill ride only has to go to 90 mph or so and someone has the picture. It only takes a few seconds to scare someone with this piece. :D
It runs good now and I'm back on the water but I'm giving it a few hours of break in time. I don't want to be anxious and break something and be back into it again. I switched to 15w 40 oil for break in and the oil pressure is way down from what it ran with 15w 50 synthetic. I have over 10 # / 1000 rpm for cruising but the pressure when it's hot is not enough for WFO. There's always something.
The v drive does load the motor harder than the jet but this 11" prop seems to have sufficient slip and the motor has no problem getting on top of it.
I really don't have a clue as to the WOT rpm.
It sounds like the rpm is 6500 - 7000.
I'm sure I could pull a taller gear.
I intend on datalogging a few runs after break in and after I switch back to race gas. Then I can confirm the rpm and the a/f ratio.

[sanger rat]

Coatings. Mark, These guys are pretty close to you. http://coat-this.com/types/index.asp