Falcon down again

Well, after one pass at the Quarter Mile for a Cure, the Falcon is down again.
We blew number 5 piston!!!! It chewed up the plug side. Not quite sure why. The cylinder wall is also scored at the location of the damage of the piston. We're taking the block to the shop tomorrow, ordering up a new piston and hoping to make it to the SCSN in Vegas in November. Just can't seem to keep things together. On the positive side, the cam timing gear/chain that Will designed looks just fine.
Guess we'll just have to slow things down to keep together for a while. It's getting kind of frustrating pulling the motor every 2 races. Though we've got it down to 80 minutes pulling the head/turbo/intake and motor in two separate sequences.
Wish us luck!!!
Kelly

That sucks!

8) perhaps that cylinder went too lean?

It appears that is the case, but we are unsure why only in that cylinder. The rest of the cylinders and pistons look just fine!?
Kelly

8) perhaps the valve lash is too loose on that cylinder?
or perhaps a bit of casting flash in the intake creating a bit of a dam?
another possibility is that when you guys did the port matching, you created a reversion problem in that intake port?
if you guys were still using the log head, i would say some casting flash in that port is creating a problem.

or perhaps you guys could get a better driver? :rolflmao: :rolflmao: dont kill me i was just kidding on that last one. you probably drive better than i do.:mrgreen:

rbohm,
Kelly probably needs to fire her Chief Mechanic!

By the looks of it were just running it right at the ragged edge! On the last pass in Vegas (her quickest pass to date!) What's the saying....."It'll go it's fastest right before it blows up!"
I did notice on the Innovate wide-band O2 that the A/F was trending up in high gear. So I think we burned the piston down on that pass.
It was still running after that of course, but did have a mild little stumble in the idle.

The block is at the machine shop getting a sleeve in #5 and I'll call JE Pistons as soon as they open in Cali and order up another slug.
Hopefully JE isn't to backlogged so they can get us a piston before next weekend. The block will be done by this Friday!
We racing again in Vegas Nov. 20-22.
Later,
Will

Does10s":1wgajvuw said:

rbohm,
Kelly probably needs to fire her Chief Mechanic!

Click to expand...

8) hmmm, how much does the job pay? i might be interested. :rolflmao: :rolflmao:

By the looks of it were just running it right at the ragged edge! On the last pass in Vegas (her quickest pass to date!) What's the saying....."It'll go it's fastest right before it blows up!"
I did notice on the Innovate wide-band O2 that the A/F was trending up in high gear. So I think we burned the piston down on that pass.
It was still running after that of course, but did have a mild little stumble in the idle.

Click to expand...

then i think you have a fuel pressure issue. perhaps going to a holley blue electric pump might cure the problem?

Rbohm,
Holley Blue? We're already using a Aeromotive Tsunami pump! I think it should be good up to 850hp or so!
We're using 1/2" fuel line both directions. Manley 4309 fuel pressure regulator.

I did however find that I installed normal sized needle & seats in the float bowls. I did purchase some of the high flow ones awhile ago but installed them into the Holley 600. So the 450 did have them. Not sure if that's the problem, but I already installed them into the 450. Just need to get another set for the 600.

The aluminum head has been fully ported, so any casting flash is definately gone. He also Flowbench'd each port so he would've noticed one port or one cyl. being different than the others.

So I'm going to pull 1-2 degrees of timing out of it, and fatten up the secondaries a few sizes.
The really good news is that my SBF timing set is looking great!
Later,
Will

Does10s":2wmcrqre said:

rbohm,
Kelly probably needs to fire her Chief Mechanic!

Click to expand...

Nah, she'll just take ya out back and shoot ya like 'Ol Yeller. Oh wait...looks like since you fixed the timing chain problem you get a reprieve.

By the looks of it were just running it right at the ragged edge! On the last pass in Vegas (her quickest pass to date!) What's the saying....."It'll go it's fastest right before it blows up!"
I did notice on the Innovate wide-band O2 that the A/F was trending up in high gear. So I think we burned the piston down on that pass.
It was still running after that of course, but did have a mild little stumble in the idle.

Click to expand...

Would you guys get booted to another class if you switched to port fuel injection and ran megasquirt?

The block is at the machine shop getting a sleeve in #5 and I'll call JE Pistons as soon as they open in Cali and order up another slug.
Hopefully JE isn't to backlogged so they can get us a piston before next weekend. The block will be done by this Friday!
We racing again in Vegas Nov. 20-22.
Later,
Will

Click to expand...

Good luck and hope you get it back running ASAP!

Does10s":x14dfowo said:

Rbohm,
Holley Blue? We're already using a Aeromotive Tsunami pump! I think it should be good up to 850hp or so!
We're using 1/2" fuel line both directions. Manley 4309 fuel pressure regulator.

Click to expand...

ok so you have enough pump, but perhaps too much return line. maybe go to a 3/8" return line instead? or put a restrictor in the line along with the regulator?

I did however find that I installed normal sized needle & seats in the float bowls. I did purchase some of the high flow ones awhile ago but installed them into the Holley 600. So the 450 did have them. Not sure if that's the problem, but I already installed them into the 450. Just need to get another set for the 600.

Click to expand...

this will also definitely cause a restriction in the bowl and thus a lean mixture, add to that the larger return line......

The aluminum head has been fully ported, so any casting flash is definately gone. He also Flowbench'd each port so he would've noticed one port or one cyl. being different than the others.

Click to expand...

what i was thinking is, what about the possibility of a minor mismatch in the number 5 port with the intake manifold being a tiny bit larger. it might not show up on a flow bench, but in the real world it might be enough to cause a slight reversion that causes that one cylinder to run slightly leaner than the rest, which could explain why that piston burned up and the others didnt.

So I'm going to pull 1-2 degrees of timing out of it, and fatten up the secondaries a few sizes.

Click to expand...

not a bad idea.

The really good news is that my SBF timing set is looking great!
Later,
Will

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Will and Kelly,

For awhile I was thinking you were super tuner man but I see you're a mere mortal. I always had problems with number 5 cylinder toasting and then number 2.
I figured it was due to:
(1) The log's head poor fuel distribution.
(2) Log exhaust header back pressure reversion (makes cylinder run lean).
(3) 5 and 2 runs hotter for some reason due to coolant water/oil.

I decided to eliminate all three by going with MPFI with the individual cylinder trim, boost controlled timing. Individual stainless turbo header.

Not sure what I'm going to do about 3. What I have noticed is, on the crankshaft 2 and 5 have no counterweights and what I think may be happening, or a contributor to the higher running temperature is the oil roped up around the crankshaft and counterweights gets sheared off by the piston skirts on cylinders 1, 3, 4 and 6 cooling those pistons better. Whereas 2 and 5 have no crankshaft near the piston skirt. Maybe piston oilers might be the way to go. Damage to the pistons, cylinder walls were always spark plug side. One would think the thrust side would run hotter but if we get back to the oil cooling the pistons the oil would shear off on the thrust side of the piston. I also thought ring gap could be a problem but they say they spin around anyway and how could they always be on the same side?

Can you post a picture of your piston, rings and cylinder wall? Or could you describe the damage better? (Like narrow blue streaks on the spark plug side of the cylnder.)

It gives you hope when the rest of the cylinders look perfect.

Do you think any of these theories have any merit?

A Holley blue pump on a turbo car? that sounds like a bad idea. Kinda old tech pump, the Holley pumps were a big deal when I was young

why restrict the return fuel line? The regulator could get confused and not regulate with boost signal perhaps?

Crosley":2zg169az said:

why restrict the return fuel line? The regulator could get confused and not regulate with boost signal perhaps?

Click to expand...

8) the problem he has is the engine is running lean, and part of the problem is that the needle valves he is using are not high flow valves. as for restricting the return line, that ensures that the fuel pressure does not drop when the engine needs fuel the most. if you look at factory fuel systems, and even top fuel engines, the return line is always smaller than the feed line.

If there is any question of block rigidity then it might be a good time to maybe start looking at running a stud girdle to tie the bottom end together?

IIRC your already using block filler up to the bottom of the water pump.

rbohm":1n2fnsai said:

Crosley":1n2fnsai said:

why restrict the return fuel line? The regulator could get confused and not regulate with boost signal perhaps?

Click to expand...

8) the problem he has is the engine is running lean, and part of the problem is that the needle valves he is using are not high flow valves. as for restricting the return line, that ensures that the fuel pressure does not drop when the engine needs fuel the most. if you look at factory fuel systems, and even top fuel engines, the return line is always smaller than the feed line.

Click to expand...

I see this as a fuel into the carb problem and restricting the return line is an artificial way to correct that. With the larger needle valves and proper pressure boost with the boost signal style pressure regulator there would be no need to restrict the return line to the tank.

Smaller return lines in an OEM application or top fuel may be related to weight savings and cost savings in OEM stuff. Some OEM fuel injection systems are now a dead head setup , with no return line.

8)

Crosley":1pp4acti said:

I see this as a fuel into the carb problem and restricting the return line is an artificial way to correct that. With the larger needle valves and proper pressure boost with the boost signal style pressure regulator there would be no need to restrict the return line to the tank.

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the larger needle and seat might be all that is needed, but since he is getting a pressure drop at high rpms, that indicates to me there isnt enough resistance in the return system, which is why you want a smaller return line.

Smaller return lines in an OEM application or top fuel may be related to weight savings and cost savings in OEM stuff. Some OEM fuel injection systems are now a dead head setup , with no return line.

8)

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nope, smaller return lines prevent pressure loss at high rpms, which helps prevent burned pistons due to lean fuel mixtures. as for top fuel cars, do you really think that a few ounces is going to make a difference in a car that is built as light as possible, and then weight is added back? on top of that, do you think a few ounces are going to make any difference to a car in which the engine makes 8000 horse power?

and yes the factorys are going to returnless fuel systems, again to prevent loosing pressure at high rpms. they do this with a variable speed fuel pump that operates with a fuel pressure sensor that tells the computer to ramp up or slow down the pump to maintain the proper system pressure, which means you just made my point for me.

rbohm,

The fuel car guys spend plenty of money to lighten all parts possible so they can locate the weight where they want it. It also has to do with acceleration and the fuel mass in the return line wanting to not return to the fuel tank

Sorry , I did not make any point for you. Restricting the return line is a false way to correct a pressure drop at high RPM.. that tells me the fuel pressure regulator is not doing it's job or the pump is not.

If there is a pressure drop at high RPM to a point below what the setup in the fuel regulator is calling for, the return line will have nothing going into it from the regulator ... your thought process on this is flawed

Crosley":347alw3z said:

rbohm,

The fuel car guys spend plenty of money to lighten all parts possible so they can locate the weight where they want it. It also has to do with acceleration and the fuel mass in the return line wanting to not return to the fuel tank

Sorry , I did not make any point for you. Restricting the return line is a false way to correct a pressure drop at high RPM.. that tells me the fuel pressure regulator is not doing it's job or the pump is not.

If there is a pressure drop at high RPM to a point below what the setup in the fuel regulator is calling for, the return line will have nothing going into it from the regulator ... your thought process on this is flawed

Click to expand...

8) i might agree with you IF i didnt have a few years tuning fuel altereds and other race cars.

Rbohm,
Fuel pressure drop? I didn't say that we were getting a pressure drop.
To be honest I don't reall know if we have a pressure problem. I have gauge mounted in the engine compartment, but that doesn't do me any good when Kelly is racing down the track! Might be about time to buy some more Innovate data logging supplies!

The needle/seat change might be the only issue. I'll find out when I get the motor back together. Wait! I can check the last pass! Kelly made a pass here in Tucson Oct. 9th. Which would be after a did the needle/seat swap. I'll check that tonight.

Anyway, Drag-200,
We've always have had problems with #5 just like you. Log head or with the CI aluminum head. So there seems to be something wrong with the block.
But you're running a 200 and we're using a 250. Although the coolant passages are probably exactly the same between the two.
We're on our third engine since we built the turbo setup. Both of the previous blocks had cyl. wall cracks in #5. Engine #2 had cranks in about everything, but #5 showed the same basic cracks as engine #1.
I was also thinking that it may be plug wire routing, or maybe even the carb hat somehow? Maybe I'll put a REALLY cold plug into #5 to help out too!

I'll take a pic tonight of the piston. I don't recall any blueing, but it's definately detonation because the immediate area around the "burnt edge" is shot peened.
Later,
Will

Does10s":fo98gsmn said:

Rbohm,
Fuel pressure drop? I didn't say that we were getting a pressure drop.
To be honest I don't reall know if we have a pressure problem. I have gauge mounted in the engine compartment, but that doesn't do me any good when Kelly is racing down the track! Might be about time to buy some more Innovate data logging supplies!

The needle/seat change might be the only issue. I'll find out when I get the motor back together. Wait! I can check the last pass! Kelly made a pass here in Tucson Oct. 9th. Which would be after a did the needle/seat swap. I'll check that tonight.

Click to expand...

8) you are right will you didnt say you were getting a pressure drop, but oyu did say that your a/f ratios were trending lean at high rpms, which does indicate a pressure drop, which is why i suggested that you were getting a pressure drop.