Motor blown on dyno tune...??

[TheToyman75]

The two plugs for each cylinder are positioned perfectly symmetrical in the cylinder head of the 3T-GTE engine. It would make no difference which one was fired to make the same power. The factory ECM fires the second plug several degrees later to aid pollution and hence avoiding potential detonation.

Actually the stock system fires both spark plugs simultaniously. And the ECM actually doesn't fire them at all its a fuel only ecu

I guess that explains why you make so little power for some much boost

[YelloRolla]

The two plugs for each cylinder are positioned perfectly symmetrical in the cylinder head of the 3T-GTE engine. It would make no difference which one was fired to make the same power. The factory ECM fires the second plug several degrees later to aid pollution and hence avoiding potential detonation.

I wouldn't say that the spark plugs are positioned perfectly symmetrical at all. Each chamber is a mirror of the one next to it, so position of the spark plug (in relation to exhaust/intake valves) take on opposite positions in relation to the mixture motion (the SINGLE MOST important fact behind spark plug placement (IMO). IF I was going to fire the spark plugs in a "single spark per pot" layout, I would use the 1 front, 2 Rear, 3 Front, 4 Rear as these are the ones that suit the port turn (again in my limited opinion). The second plug is not fired several degrees later, they are fired simultaneously, and as pointed out by Toyman, the spark is not controlled by the ECU (the advance weights and vacuum canister are a dead give away).

I found no difference in detonation threshold by switching the spark plugs off either. Having two spark plugs in the one hole effectively gives you double the spark energy, and potentially cleaner emissions are achived by giving a more complete burn throughout the combustion space.

Now to the GW's problem - RMS is right and so too TRRRunner. The combustion has leaked passed the gasket and pushed the water out. This is almost certainly due to detonation.

On the path to possible solutions, do not use that dyno tuner again and when putting it back together; use head studs, hylomar, O rings - all used in conjunction with each other is good. This will give some tolerance to poor tuning (detonation) BUT you cannot insure against idiots. Fcuked tuning will either break things, or give shit performance or both - everytime, no exceptions.

Sorry to hear of your predicament.

[The GW]

thanks heaps for the advice mate...so given that the air fuel and manifold pressures are or, do you think timing wouldve been responsible?

also what head torqueing technique do you use? ryley suggested the one they used on his head gasket which was torque, then not boost for 500 ks, re torque, then JUST hit boost for 500 ks, retorque and its all good...also do you recommend just running standard tension on the head or revise it?

unfortunately it was all new head studs and o rings and everything with the rebuild, done by idb in melbourne

[YelloRolla]

edit/ If the AFRs are ok, then it is most likely that timing is the issue. I would say that shit fuel could've been the cause, except that as it was being tuned, someone should have been able to stay out of the detonation zone (or be in it very briefly), but as none of us were there to witness exactly what happened, then you need to go over things and check that they're right - like RMS pointed out, head and deck flatness first.

With the JMR head studs and O rings, I torque to 75ft/lbs, drive it however I want and re-torque at 500K.

Are you sure that it is O ringed and has head studs?

[whatthe?]

Jase, what material do you use for your head gaskets?

GW, sorry if this has been asked, but is that a metal HG? My screen quality aint fantastic, but it looks very graphity to me. If it is, what good would O rings be anyway?

[YelloRolla]

I use just the normal Toyota composite gasket. The O ring locks down on the fire ring approx 2/3 of the way back and makes moving it harder. Detonation will push it's way past anything, this just gives more time before it gets past.

[whatthe?]

Cool, just didnt see any O ring marks on the fire rings of his gasket. Perhaps theyre on the other side. No-one makes metal HG for these engines?

Gotta be honest, never heard of anyone O ringing composite gaskets. Everyone Ive seen do it has used copper. Obviously your rolla is proof it works well if done properly

[DX20VT]

IMO, If a dyno tuner is not using knock detection right from the time the car is warming up on the dyno then find another tuner.

Every time I go to the guys who tune my car, they always check base timing and hook up the knock defore anything else is done.
It's a bit annoying that they waste a little bit of time every session rechecking the base timing even though I know it has never changed,
but for they do it for a reason and I rather get it done than risk an engine failure.

[whatthe?]

Serious question here - If you dont have active knock sensors because the ECU doesnt support what do they hook up for knock detection?

[fixeruperer]

its like a big alligator clip they clip onto the engine somewere.
and they listen to it threw amplified sound.

[DX20VT]

its like a big alligator clip they clip onto the engine somewere.
and they listen to it threw amplified sound.

Or they find a thread in the block and screw a donut type sensor in there to use.

[LeeRoy]

Matt, linden has a set of them. Its just a set of headphones with a few channels so you can run multiple inputs. You just put the clips on the engine and if your using more than one place them in a few spots. Just throw the headphones on, adjust volume and listen for knocks, then if running multiple inputs just switch between them ie listening for knocks at different areas of the engine.

Basically its just a stethoscope for motors.

I guess why you hook up knock detection is much like hooking up an 02 sensor on a car whos ecu doesnt run an 02 sensor. It is still used because if your tuning and start to flirt with pinging and detonation you wont hear it without the headphones and there would be nothing worse than tuning an engine and sending it off with a knock in some part of the rev range.

Keep in mind it has to be a pretty big knock to be able to hear it without any assistance. At the same time however a good tuner should be able to tune without them by using all the other things that they use.

[Dieseltrain]

Did the tuner actually go through your Current tune and look at the timing maps before making adjustments and going ahead and finding out that 30 degrres timing was too much ( figure is an example ).?

The couple of tuners i know, will always check someone else work before moving on.. Using their own knowledge they will either A) start some trial runs and see how things go ( if deemed safe enough ) or B) will remove timing back to a safe level and then tune it up from there, preventing any chance of something bad happening on the dyno...

Also, timing maps may not be changed but the car might be started off on a very low boost setting and see how it goes from there. Knock detection is a must.. It kills engines.

[kojab]

Actually the stock system fires both spark plugs simultaniously. And the ECM actually doesn't fire them at all its a fuel only ecu

I guess that explains why you make so little power for some much boost

Thanks for your input Toyman75.
With regards your response "Actually the stock system fires both spark plugs simultaneously." From my experience the conclusion I have drawn is such that I disagree with you and the reason the plugs are fired one after the other is to aid in emissions and efficiency, however after saying this I am open to changing my opinion provided suitable documentation supports the alternate opinion.

[kojab]

I wouldn't say that the spark plugs are positioned perfectly symmetrical at all. Each chamber is a mirror of the one next to it, so position of the spark plug (in relation to exhaust/intake valves) take on opposite positions in relation to the mixture motion (the SINGLE MOST important fact behind spark plug placement (IMO). IF I was going to fire the spark plugs in a "single spark per pot" layout, I would use the 1 front, 2 Rear, 3 Front, 4 Rear as these are the ones that suit the port turn (again in my limited opinion). The second plug is not fired several degrees later, they are fired simultaneously, and as pointed out by Toyman, the spark is not controlled by the ECU (the advance weights and vacuum canister are a dead give away).

I found no difference in detonation threshold by switching the spark plugs off either. Having two spark plugs in the one hole effectively gives you double the spark energy, and potentially cleaner emissions are achived by giving a more complete burn throughout the combustion space.

Now to the GW's problem - RMS is right and so too TRRRunner. The combustion has leaked passed the gasket and pushed the water out. This is almost certainly due to detonation.

On the path to possible solutions, do not use that dyno tuner again and when putting it back together; use head studs, hylomar, O rings - all used in conjunction with each other is good. This will give some tolerance to poor tuning (detonation) BUT you cannot insure against idiots. Fcuked tuning will either break things, or give shit performance or both - everytime, no exceptions.

Sorry to hear of your predicament.

YelloRolla, I guess we are both correct because each combustion chamber may not be symmetrical to each other due to the mirror image effect, however they are all symmetrical with respect to the spark plugs location in each combustion chamber.