This is all I have left of my car :( *PIC*

[Andrew Bolt]

1UZ - Century or Crown

See sig. Dishing out the ownage is fun too.

[carcrazy]

Man thats nasty, friend who owns a dyno tuning shop just bought a flywheel balistic blanket for occasions like that.

Ive seen pics of one go through the tunnel and up through the dash never to be seen again, took two of the drivers toes off too.

[ccpl]

Here is my analysis of what happened. Big smoky single spinner then diff decides to spin both and the thought of a VL doing a double legger the flywheel does what it sees as its duty and self destructs so as not to upset the balance of nature.

ROFL. Yes i agree totally with this statement.

No force on earth can envisage a VL doing a 2 wheel skid.

[jmac]

I'm going to make a leap of faith that it had a fuel cut probably somewhere above 7000rpm (I don't honestly know) so I'd like to know, and would really appreciate complete honesty (don't put it lower to make yourself look less of a goose, as there's some valuable data here if you are completely honest)

What rpms did you tend to let it spin out to when doing burnouts or in the lower gears hooning around? Honestly.

Gotta echo other peoples comments about flywheel choice. It'd be nuts (considering how cheap they are compared to the potential bill from one letting go) not to run a steel one. Another thing - Replace with new grade 8 bolts every time you take the bloody thing off. I'd suggest grade9, but afaik they are only available as socket head capscrews (the things you undo with allen keys or inhex sockets) and possibly won't clear things.

John McKenzie

[Wobbler]

Hmm, *eyes up L14 that is going to get a hiding*
What are the L series flywheels like? bodgy like an RB?

[BigMuz]

Can I add to John's comments and ask did the clutch slip at all- did you pull second gear?

Muz

[Dave]

I vote for either EH with LS1 or 1uzfe in a RA40 celica,

I had an RA40 as a first car and I abused the living hell out of it, burnouts, racing, rally. The only thing I ever broke was a tooth off the diff. I hour and a new diff was there!

[Jim]

Hmm, *eyes up L14 that is going to get a hiding*
What are the L series flywheels like? bodgy like an RB?

Yes, but don't worry, the L series is rev limited by a cleverly designed side flow 2 valve head. :rotflol:

[dhs]

Can I add to John's comments and ask did the clutch slip at all- did you pull second gear?

Muz

No slipping- I had a friend install an Xtreem brand heavy duty clutch a few weeks earlier. Started in 1st, changed to 2nd, revs were sitting at just below 7000rpm and didn't bounce off the limiter (7400) which I had hit many times without problems. Although not during a burnout.

[jmac]

Can I just mention that everyone in the world can hit the rev limiter many times without problem, until they have a problem (it'll make sense if you think about it)

Years ago I worked at a servo as a third job on weekends, and a guy wanted me to fill an lpg bottle that was so rusty I couldn't even find where the last test date was stamped on it, let alone read it. I refused to fill it. He said 'I've never had a problem before' and I was thinking, 'he'll never ever say he had a problem last time, since when that actually happens, he'll die as a result of it'

It's good info though (seriously) and I thank you for it. If anyone else cares, would you believe with a turbocharged engine, you'd likely be safer revving in gear (at full boost) at 7400rpm than 7000rpm undergoing a fuel or ignition cut. You'd be in far less danger of throwing a rod. I'll post why if nobody gets it.

John McKenzie

[piss98]

Post it pls jmac!

[BigMuz]

Under load is essentially steady state- bouncing off the limiter is a transient, and involves stress reversals- ie the deceleration then the acceleration of the flywheel.

Bottom line is RB anything manual- change the flywheel- cheap insurance.

The reason I asked about the clutch is that I have seen flywheels let go when they get red hot due clutch slippage. You just replaced yours so I will accept that it probably wasn't that. If the clutch was a bit dodgy, a 2nd gear burnout is probably the most testing thing you can do to a clutch ( other than a 3rd gear burnout :D).

Does anyone remember the first burnout comp at Eastern creek where Craig Lowndes drove some random guy's falcon years ago. A gemini sat there for about a minute thinking it was burning the tyres, but it was actually smoking the clutch. Eventually the clutch exploded in a frightening bang and coolant got on the road- think about it. That guy was lucky that the stupidity of the marshals in not stopping him didn't cost him a leg.

Muz

edit- my spelling sucks pretty bad.

[jmac]

okay the (as short as I can make it) version

When a rod lets go, it's more or less all down to one thing.

At bottom deadcentre as the piston is turned around from downward motion, to coming back up, the bearing takes the load (as does the oil film/pressure between the journal and top bearing shell. It's practically impossible to break there (you'd more likely bend it if the engine hydraulicised to due to water or fuel completely filling the cylinder before hte piston was at tdc and forming a hydraulic lockup.

AT top dead centre, the lower bearing shell does it, but the only thing holding/pulling on the piston is the rod and rod bolts. SO _that_ is where it will let go. Typically a bolt will eventually snap, or the rod can too, at certain weak spots (typically around the bolt 'head' area, and somewhat less common on any race app, as race oriented stuff is generally very beefy on that front.

SO it's crying out to break on the reversal of the piston at TDC. EVen if it ends up being flung out the side in the end.

Now, on the compression stroke, as the piston approaches TDC there's considerable (perhaps over 300psi on some setups) pressure acting on the piston - helping the rod from all the way on top of the piston. So it's less likely to break. additionally, near TDC on the compression stroke the spark fires the mixture, so you actually have a further increase in pressure before hte piston has made it to top dead centre. So it's well cushioned and if the rod does go, it will do it on the exhaust stroke (where there is stuff all pressure, so it's up to the rod cap and bolts to do all the pulling so to speak.

This was totally stuffed up in a column in street machine a year or two back. They suggested that on deceleration the higher intake manifold vac pulls on the piston and snaps it. Which is ridiculous. Even if you had _absolute_ vacuum on top of the piston, it'd only see (max) 14-15psi acting on the underside of the piston (since atmo is 14.7psi, the max differential is that 14-15psi roughly). Which is stuff all of a pressure differential compared to the _lack_ of pressure on top of the piston (i.e. zero absolute worse case on decel, but 285-300psi or more _added_ pressure assisting the piston at tdc on the compression stroke. SO it's not the vac on top of the piston, it's the lack of substantially higher pressure on top (compared to the comp/ignition stroke) that makes the exhaust stroke the weak link. You could go further and say that any decent race engine will have crankcase evacuation that actually leads to high crankcase vac, so on decel, in the real world there won't actually be that pressure differential - it'd be close to negated - i.e. the vac on top of the piston is similar to that below.

So now it follows that lack of pressure on top of the piston is a concern. And a turbo engine at full boost and near maximal rpms will have exhaust back pressure (generally higher than boost pressure) - and that's the case on any turbo setup once you pass the point where the wastegate starts to open. So as such, it's adding a little bit of pressure on top of the piston at tdc at the end of the exhaust stroke, so it will in that instance assist the rod in hanging together. It's still not up to the amt of assistance it will get on the compression/ignition stroke - but it's better than nothing

With a rev limiter, it'll cut fuel or spark, so there's stuff all combustion prssure on the end of the compression stroke (as the mix would otherwise start to burn) - so it's far closer to being as unprotected as it is on the exhaust stroke (non turbo in particular). SO it's having to deal with that tensile stress (Is that the right term) twice as frequently, and will end up in trouble in half the time (theoretically)

Bouncing an engine off the rev limiter for extended periods can also lead to the crank failing (as long as it's curently in an application/setup where the rpm it gets the fuel or spark cut is near it's limits (if you had a rev limiter set at say 1500rpm lower than the engine is known to be able to spin to all day and all night, it'd be inconsequential). At the back of the crank is the flywheel/clutch or torque convertor. So it dampens out crank flexure (at least to some extent). up front, there's a (relatively) smallish balancer (or more accurately damper). every time a cylinder fires, it pushes on the crank, and tries to flex it one way. The heavy clutch etc cushion and absorb it, and it tends to 'tension up' for when the next cylinder fires, and handles it find. Up the front of any cylinder firing, there's stuff all helping to stabilise the crank, so it can whip back and forward 'swinging in the wind' and at certain rpms can and will. Although it's not 100% terminal, most balancers are designed and built to best suit either the most dangerous rpm range that this engine sees max crank flex, or to work best in the rpm range normally operated in (say on some production cars).

They work ok in that scenario. but if you've got cylinders cutting out, and not firing, the pattern (and possibly frequency) of crank flex is no longer the same. Of course the best dampers are those that are fluid filled (as they actually work over a considerably wide rpm band, whereas the rest only work well over a particular smaller rpm range). Anyway, point being that it will cause unpredictable crank flex, and lead to breakage.

Then there's also the matter of the limiter itself and how it works. On some engines, even the burn of one or two cylinders is enough to push the rpms in excess of the rev limit. I.e. it crosses past the rpm 'limit' because it's spinning fast enough to pip past it from one cylinder, so even if the management responds instantly, it'll still take a fraction of a second for the revs to drop (even with no further burns till the rpm is back to a safe level). This is more likely to happen if someone sits on the rev limiter at full throttle, using the rev limiter to stop the rpms. Because then the next a/f charge will be near 100% ve, if it is lit, it'll surge past that trigger rpm point. And so it ends up dancing perhaps a hundred rpm or more above it's intended fuel or spark cut. Judging by the footage I've seen of a car on the net, the the rev limiter is slower to respond that ideal. It's of a guy lining up to race another car, he keeps it on the limiter then takes off hard, with the engine falling to pieces a hundred metres or so further along. The interesting thing with that is the time between one spark or fuel cut, then how it reactivates, then cuts. It only does it a few times per second, with some gap between the next reactivation.. Which means it can and indeed does end up spending time some point higher in the rpm range than the rev limiter is technically setup to prevent

Perhaps a google for files with the following keywords - I seem to recall it might have been discussed here (I do recall it popping up in aus.cars too)

E46_M3_VS_Eclipse_GSX.wmv

aftermath-low.WMV

John McKenzie

[Rollin]

bugger me. i never understood why it was bad to rev a car hard in neutral (though i did understand it was pointless...) and that explains it all nicely.

awesome

[I Wish]

How about this guy.

No insurance as well.

http://www.booyamotorsport.com/rip/