Discussion in 'Fiesta ST Maintenance' started by Atlas4gr, Dec 18, 2013.
I can't help but wonder what happened at 20 sec. when the sound changed.
More details or ban
So, this is what happened. The engine is running at low idle speed on the dyno at the start of the vid and then its speed is slowly increased to what is refer to as high idle-maximum governed rpm. Its a diesel engine. At around the 25 second mark when the note changes, full load is applied to the engine. The only thing I would comment on is that the dyno operator screws the load down too abruptly IMHO, although this would not cause a failure like the one you see.
Two things, its not very high rpm so its not the same type of failure as a missed shift and secondly you could hear it wasn't happy for a few seconds before things start to break.
I'm guessing it was an oil starved rod bearing that seized, broke the rod and then swung the broken rod around taking out the block. I think it was a heavy load and probably detonation that made the oil starved bearing fatal.
It's a diesel, it runs off of detonation. Without knowing what the revs were or anything else it's impossible to say what killed it.
Our F1 valvetrain was good for about 23krpm, which we never took it to except on the rig. For a couple races in 2000, we shortened the stroke even further than it was, and ran at 20krpm. Yes on the pneumatic springs(at extremely high pressure, if I remember correctly from my F1 days) plus very lightweight titanium valves. One more thing that astounded me: zero valve clearance. Yes, they are designed to touch the piston at max rpm!
In contrast, NASCAR valvetrains are massive and very compliant, thanks mostly to their insistence on using pushrods(cam in block). It's a catch22: to design a stiffer valvetrain requires large diameter, stiffer pushrods, which add to the weight problem, at the worst place possible: very far from the spring pack. As a consequence, modern profiles are designed to "toss and catch" the valvetrain. When they first discovered this was happening, they designed the spring package to eliminate it, since it was destroying engines. Later, they put some science behind it and controlled it. Now they're intentionally built that way, instead of accidentally. Short tracks will take the engine to 9,500rpm all day long, right before the braking point, which is much harder on the engine than longer, high speed tracks that don't venture much about 8500rpm or so. Few hundred rpm makes a huge difference in longevity, and I'm still amazed they stay together for 500 laps. One of my buddies at Yates once told me whole car is pretty much trashed after a short track race, not just the valvetrain and body.
A comparison, NASA Cup and FIA Formula 1.
That is very interesting reading. I liked that a full out race engine is putting out 140 hp/liter while our little Fiesta is putting out 123 hp/liter!
The new 2.3L Ecoboost in the 2015 Mustang is rumored to make 143 HP/Liter!
Nice dang near 330 hp .. anyone say engine swap ???
In the spirit of fairness, you're comparing a naturally aspirated race engine against a boosted production engine. The naturally aspirated Honda S2000 made 120bhp/L. The wickedest F1 full race turbo engines made damn near 1000bhp/L. But the Fiesta ST is MUCH more tractable and practical than any race motor or the S2000(which required very high revs to reach it's 240bhp).
I confess: my family has one drive way, and I keep trying to make sure my Fiesta is the last car to park in it, so that if someone needs to run to the grocery store or anything, "Hey, I'll go!". Wife keeps telling me lately, "Thanks for doing all the driving, honey."
Separate names with a comma.