The 24 Hours of Lemons Forums → Lemons Tech → Why do we keep throwing rods?
Remember, there are no bad answers, lets just brainstorm here...
Billy Beer:
Car - 1979 Ford Fairmont Futura
Motor - Ford 200 straight six (Mustang/Falcon motor)
Transmission - T5
Ideas?
Remember, there are no bad answers, lets just brainstorm here...
Billy Beer:
Car - 1979 Ford Fairmont Futura
Motor - Ford 200 straight six (Mustang/Falcon motor)
Transmission - T5Ideas?
Have you checked your injectors? This seems unlikely but
What was your oil pressure like prior to the incidents? Do you you have an oil pressure gauge + do you run your engine with 0.5-1qt more oil?
http://www.ford-trucks.com/forums/68272 … n-rod.html
Finally, Did you overrev the engine?
http://www.forumsforums.com/3_9/showthread.php?t=66108
What were the bearings looking like prior to your race?
We found the secrets to keeping our 20R alive is much the same as a SBC and may well apply to a Ford 6.
Get a rear end ratio that uses the low down torque we have a 3.5x rear end and only use 5th gear on Road America. Does the ford make low down torque?
Rev limiter set at 4750
Good race oil (Schaeffer 7000 20w50) http://webstore.schaefferoil.com/s.nl/it.A/id.2721/.f
Crank scraper
Oil cooler
Good race oil (Schaeffer 7000 20w50) http://webstore.schaefferoil.com/s.nl/it.A/id.2721/.f
In the Saturn, we use good racing oil and change it after each race day along with the filter. It is imperative that you also keep things running cool. The little Saturn engine loves to spin and we are regularly getting to/hitting the 6700rpm rev limiter. I think the engine may finally be on its way out after 8 or 9 races taking that abuse. The bigger engine will probably need to be spun slower. Also make sure your cooling system is working well.
We managed to keep the Rover from exploding by making sure the cooling system is set up correctly and a good oil is used.
The importance of keeping the rev downs can't be overstated. What do your drivers aim to shift at, and are they actually following that guideline?
3 Pedal Mafia has managed to take two of the "most problematic" motors in Lemons and make them last .. and last .. and last by keeping revs down. Shifting the Chevy 4.3 at 4xxx rpms and the Honda 1.8 at 6500rpms has led to a lot of trouble free races. Or at least, it wasn't the motors that caused any troubles we did have.
As people have mentioned, keeping revs down definitely will help. We'll spin our SBC up to around 5,400 if we're really going to wind it out, otherwise we generally shift lower than that. In my experience, it's more important to keep the motor cool, and keep the oil on the bearings. Do you have any soft of pan baffles? Oil cooler?
Has anyone on the team watched the oil pressure gauge while you're turning? If you're low on oil and/or have poor oil control in the sump you can actually watch the gauge go to 0 in turns, and then climb back to normal on the straights. As a driver it's hard to get used to checking oil pressure in turns, but if you don't you may well be ignoring a critical early warning sign that you're about to blow a motor.
As people have mentioned, keeping revs down definitely will help. We'll spin our SBC up to around 5,400 if we're really going to wind it out, otherwise we generally shift lower than that. In my experience, it's more important to keep the motor cool, and keep the oil on the bearings. Do you have any soft of pan baffles? Oil cooler?
Has anyone on the team watched the oil pressure gauge while you're turning? If you're low on oil and/or have poor oil control in the sump you can actually watch the gauge go to 0 in turns, and then climb back to normal on the straights. As a driver it's hard to get used to checking oil pressure in turns, but if you don't you may well be ignoring a critical early warning sign that you're about to blow a motor.
Easy way to solve that is to rig a siren to a low oil pressure sensor instead of an idiot light. It's easy to miss a light especially if it's flashing on/off briefly in turns when there's traffic around, but it's pretty hard to ignore the Taiwanese National Anthem (as Judge Phil puts it) when it's going off right next to your ear. I've almost done this with a shift light for one of my drivers.
-Is the clutch and flywheel balanced for that engine?
-Are the bolts letting go or are they letting the cap walk around under load? Some better bolts might help that.
-Do you have baffles in the pan? I saw this mentioned above as well. We snipped pieces of sheet metal from the folding rear seat frame and made a bunch of baffles to keep the oil around the pickup in the turns.
From what I'm reading the rods are relatively(but not super) short compared to the stroke. If my basic engine knowledge is correct, your engine will experience a lot of rod angle. When you're turning higher revs that puts a lot of strain on the rods and can help in removing them from the crank/piston/block. How high do you guys rev the 200? I'm reading 4500 redline for stock bottom end.
The motor we just blew WASN'T a stock bottom end. It actually had had more prep work done on it than any of our other motors. I didn't build it, Dave who is storing the car now did. But there was balancing, new bearings, and good APR bolts/studs used in most of it. And yet it blew up with less racing miles on it than any other motor we've run.
The motor that let go at Sears Point at the sprint race in spring was a "rebuilt" motor off of Craigslist, topped with the modified cylinder head we've used on nearly all of them (the intake manifold is part of the cylinder head). That motor was our only motor for the 2013 season. Sure we sat had transmission issues on Saturday at Sears Point 1, and a head gasket going bad at Sears Point 2, but ran hard all day at Buttonwillow, and 1 of the 2 days at both Sears Point races.
It never runs hot unless its out of coolant. It never shows any signs of oil pressure fluctuation.
is it breaking rods, caps, or bolts? I assume that it isnt breaking off the bottom of the piston at the wrist pin.
The motor we just blew WASN'T a stock bottom end. It actually had had more prep work done on it than any of our other motors. I didn't build it, Dave who is storing the car now did. But there was balancing, new bearings, and good APR bolts/studs used in most of it. And yet it blew up with less racing miles on it than any other motor we've run.
The motor that let go at Sears Point at the sprint race in spring was a "rebuilt" motor off of Craigslist, topped with the modified cylinder head we've used on nearly all of them (the intake manifold is part of the cylinder head). That motor was our only motor for the 2013 season. Sure we sat had transmission issues on Saturday at Sears Point 1, and a head gasket going bad at Sears Point 2, but ran hard all day at Buttonwillow, and 1 of the 2 days at both Sears Point races.
It never runs hot unless its out of coolant. It never shows any signs of oil pressure fluctuation.
We need more data. What is the oil capacity? Have you checked oil temps? Are you running an oil cooler? What do the engine temps (coolant) look like during the race?
We put in a bigger radiator and an oil cooler. Our engine starts with an 8 quart sump, and the cooler and lines add a little more capacity.
I would look at increasing your oil capacity, increasing your water and oil cooling, and limiting revs.
bs
What is the mode of failure scorched bearings? snapped rod in the middle? Pin ripped from the piston( I know, its hard to say if it was before or after it went bang)?Rod bolts broken is likely what you will say but why, was the bearing trashed or was a perfect bearing found in the pan wadded up but otherwise unworn? What was the rod bearing clearance? Are you monitoring oil temperature?
As everyone said, Inline 6 engines dont like RPMs, run low use the torques.
Oil light, get a 20 psi sender, the stock one will not alert to oil loss in the turns as pressure drops enough to cause damage but not enough to trigger alarms with the stock sensor settings.
If it's bearings that you're losing, go with an Accusump or similar accumulator. I've been able to score a couple at swap meets for $50.
The motor we just blew WASN'T a stock bottom end. It actually had had more prep work done on it than any of our other motors. I didn't build it, Dave who is storing the car now did. But there was balancing, new bearings, and good APR bolts/studs used in most of it. And yet it blew up with less racing miles on it than any other motor we've run.
And it being a big heavy inline 6 those changes still won't make it like to rev. If you're shifting this thing at 5500rpms or something then that's the cause of your problems. Do you know what they were shifting at?
Revving higher doesn't make you faster, I've passed plenty of people while I was loafing at 3500rpms in the boat. Well, plenty of C class cars. ;-)
According to my math (we don't have a tach), the Dart is shifting into 3rd at about 3300 RPM. This is probably the only reason we haven't destroyed our engine yet, considering it corners really well and we still haven't baffled the oil pan.
Our straight 5 never shifts itself over 4000 that we know of and I'm very glad of it. The oil pressure gauge stays pegged at 3bar. Low RPM and high PSI are your best friends.
What sort of oil are you using and do you have an oil cooler?
More info on the exact failures helps too, but like others have said, keep the revs down.
How is the actual flow out of the oil pump? That's one of the secrets in keeping our Honda D16 alive for about 8000 race miles (after a lifetime of who knows what before), is that we ported the oil pump, as stock it will cavitate a bit a higher RPM, and porting lets it flow more smoothly.
Not that its worth much, but these engines were being redlined at over 5000rpm in the 60s when they were designed. The bottom end is more BMW like than Stovebolt six like (the cylinder head is another story).
We've had an oil gauge since day 1, and the pressure never goes down. We had a factory electric gauge, not its an aftermarket mechanical, still same readings.
Water temps on the factory electric were not even above the O in "normal", now we have a mechanical and its reading below 200, unless we lose our coolant.
I believe the factory sump holds 5 quarts, and we always run it 1 quart overfull.
As far as failures go, the first one was just over revving it (7-8000rpm on the inaccurate factory tach) but the piston came apart, the rod was intact. I put that one together, so I know it had new bearings and cheap Silvo-lite Sealed Power pistons in it (hypereutectic), stock bore as bored by Ford and run for 100k miles.
I mention that motor because that one blew for a known reason, and failed in a way differently than the other two. Basically the same motor set up (cylinder head modified for a 2bbl carb, home made header, 264 degree cam shaft) has been used ever since, but with bottom ends scored off of Craigslist.
Next Craigslist motor was a supposed rebuild, but we know nothing for certain, except it had dished pistons like the one I built, and we reused the head (after fixing the 1 destroyed cylinder) and camshaft. Because I swapped the heads I know it had a modern composite head gasket (Ford used a .025" thinner stamped metal one). This motor ran 3/4 of a race at Sears Point in spring of 2013 (transmission issues) all off 105 degree Buttonwillow (head gasket weeping), and 1/2 of Sears winter 2013 before the head gasket blew. It was replaced at the track with the NOS Ford stamped metal head gasket we had with us. Here is what happened in practice for the Sears Point 2014 sprint race.
Dave who took it apart, and built the new one (its living in his garage now) said some of the rod bolts were just finger tight when her took it apart.. He took it upon himself to put the new motor, built from a craigslist runner, together with all the good stuff. Personally I felt like he was getting a little cheaty with ARP hardware, hot tanks, and balancing and stuff... But here we are again with another ventilated engine block. I know he used ARP rod bolts, and that this core just happened to have what are considered the strongest rods Ford ever put in these motors.
We've been running Rotella diesel oil 15w-40, with a quart of Valvoline VR1 mixed in for its extra added zinc content.
So far I have 3 theories, after plotting the motors we have used, what was done to them and how they failed.
1) Too much compression on regular gas? I haven't heard any knocks or pings since our first Sears Point race, and that was just ignition timing. The reason this is #1 is that the 1st motor to throw a rod lasted 3 weekends, then blew up almost immediately after getting more compression via the Ford headgasket
2) Manual transmission + engine braking = much more stress than running flat out all day with a C4 auto? The problem with this is The first motor backed with the stick lasted 3 race weekends, and 2 full races worth of laps.
3) Local machine shop overbores with no torque plates are no where near as round as the stock Ford bore. The motor I put together with just a hone and stock size pistons came apart in a totally different way than the others, which I assume were both overbores.
There's your problem Woody. Start using the cheapest oil, engine parts, don't run a thermostat, and put in a cheaty aluminum radiator to keep her cool.
You love it too much, therefore it will not last, this is a lesson I have learned the had way in life.
Our Rambler shifts at 3500 RPM, now has a rev limiter, by that I mean a kick down circuit that does not work properly and kills the motor when you floor it, runs at 150 degrees without the thermostat installed, and runs cheap Napa oil in it.
I have not had much experience with 6 cylinder motors, actually owned only one car the Rambler with a 6, but it seems to me after driving one that just slowing down a bit, keeping the rev's low, and keeping it cool will do a lot to keep it alive.
I am shocked at how fast that car is with a straight 6 every time I am on the track with it.
I thought a thrown camshaft was the cause of the second engine's death?
I thought a thrown camshaft was the cause of the second engine's death?
The broken pieces of rod forced the cam thru the block. See the flat spots on the cam? Those are ground in there because the crank throws on the 250ci version would hit the cam otherwise. That's how close stuff is in there.
Our speed on the track isn't much to do with the motor. I doubt we even can put 150hp to the wheels. We just have the chassis very predictably set up now, which is why I don't want to drop an extra 200lbs in the nose.
Did he hone the rods when he went to the ARP bolts? Because when you torque the good stuff to it's preload, it's a metric shitload more than the factory junk....
Now the rod end is out of round and you pinch the bearing and............
S/F.....Ken M
FYI, the rev limiter was set at 5000 and drivers were shifting at 4500-4700. Oil pressure held steady thru the long sweeper and coolant temp stayed at 180. There was a very noticable vibration above 4000 RPM that should not have been there. Never heard any detonation but it was loud in the car.
Look at the piston on tear down. Detonation will damage the piston top but usually not hurt the rod...it just loses compression.
If the piston got hot enough to seize in the bore, it will pull the pin out and the rod swings around breaking stuff. If aluminum is gaulded on the cylinder walls, that was it.
If its a lack of lubrication, the bearings will be wiped out and metal transfered to the crank. If the crank journals are good, so's the oiling.
If none of the above, it's a mechanical failure of the piston or the rod bolt.
The 24 Hours of Lemons Forums → Lemons Tech → Why do we keep throwing rods?