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Discussion Starter #1 (Edited)
obviously there are a number of factors that can contribute to an engine failure. The one I'm considering at the moment is of course, the map.

I had initially mapped it conservatively. Knock never went above 10, and the car felt sluggish, laggy as hell, and was slow to respond in general. So I increased the ignition timing, particularly in the 1st quadrant of my PFC map (rpm 1-10, load points 1-8), but kept the high load/high rpm settings the same. I added fueling to the rest of the map, but leaned out the above quadrant, particularly the highway cruise cells (load 1-6, rpm 3000, and the one above and below it), in an attempt to improve upon the shite 12mpg I've been getting. The car turned into a monster, reacting almost violently to the slightest throttle inputs, and with stock turbos and rebuilt internals at 1.4bar, I ran a 10.87 quarter mile and thrashed a Maserati Coupe on the highway just days before my engine suddenly melted down on a relatively sedate highway cruise.

On the new map, knock never went over 27, but in reflection, the knock bar *acted* like it was knocking, spiking and popping, during any spirited driving. I rarely was able to apply full throttle, because, well, I'd run out of road too fast. Just blips to get that rush of speed.

So anyways, my thoughts are that my map was really on the razors edge - a map that a race car would use to get the maximum out of an engine for 2-3 hours of hard driving.

However, my mechanic is of the opinion (as we talked about the engine with its guts spread out all over the floor), that a single massive detonation event caused the damage, triggered by the fuel pump failing.

the engine damage is as follows:
- valves are ok, but the head is unusable, as the area around the valves (the flat semicircle parts, 2 per cylinder) are completely fried, as if the metal had been deep fried.
- all six pistons are also fried - piston rings toasted and the piston sides are all gravelly.
- block is of course, scratched up, but very lightly - a 0.5mm overbore and hone will easily take care of that
- N1 oil and N1 water pumps are fine
- no gaskets blew
- some oil leaking from the rear turbo. If the engine really did go from just the fuel pump failing, then this oil leak may just have been the result of the infamous 2 bar test. I don't know how much oil was leaking, but for many reasons, I'd rather not reuse these turbos.
- not a single bearing spun. The crankshaft is in perfect shape.
- cams, valves, and cambelts are all ok as well.

So in order to rebuild, I need to:
- bore out the block
- put in new pistons (and do the conrod bolts while I'm at it)
- replace the conrod bearings (these come in different thicknesses, which one do I want??)
- get a replacement head.
- put in new turbos

I'm still waiting to inspect the Tomei engine from a wrecked Skyline that's being offered. My thoughts are to buy that engine and put it in (which would get me on the road by the weekend!), and then rebuild the bottom end of my engine and set it aside. Looking at my track record, that'd probably be a good idea.

other thoughts:
- is running twin EGT gauges (one for cylinders 1-3, one for 4-6), just before each turbo overkill? Or do the cylinders really run at different temperatures?
- is having a CHT (cylinder head temp) gauge useful at all?

- I'm seriously thinking of flying a tuner in from Japan to map my car, as, frankly, I (very roughly self-taught) am probably the most knowledgable PFC guy around, and that is SCARY. Korea is HKS FCon land. For 2 grand, it'll cost quite a bit. But I'd also like to hear opinions about whether an engine dies gradually from a "hot" tune, or if engines die from a single catastrophic event.

My mapping (yes ScoobyT I get it!) was without the benefit of EGT and very little wideband lambda time. I'll have both installed in my car this time around. I've already learned that mapping is a balance, and from extensive road mapping, safer maps are had at the direct expense of performance. Or can someone teach me how to have my cake and eat it too - for example, controlling EGT and knock by overfuelling a map cell, versus retarding the timing?

After looking at the burned insides of my engine, I was thinking "water injection, water injection"...but does anyone really have a fully working and tuned streetable water injection system?
 

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Jebus!!

Man that sounds harsh, Do hope you get it all sorted, on the one hand getting it properly tuned by a pro will save you money in the long run, on the other as you said its kinda expensive. But i fi was you and had the money to do it, i would, that way, id know it was a solid tune.

All the best!
 

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The primary difference between a `safe` road map and a `safe` track map is the amount of fuel enrichment used and the margin to detontation.

For a road car you can make a case for less enrichment and running closer to BLD timing. This combination may yield a bit more power and torque and better economy. This is based on the assumption that you cannot rag the car continuously hard enough to properly heat soak the combustion chamber, intercooler, exhaust manifold, turbo, coolant, oil etc etc.

In a track enviroment you clearly can reach a steady-state condition with the above components and this would drive additional cooling requirments with fuel and more margin to BLD (also requiring more fuel).

The spark timing comments are of course only valid for an ECU that does not run closed loop knock control.

Personally I set my maps to be safe under all conditions.
 

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Maybe something you need to also consider is reading some books.

I appreciate you have to do the best you can but there is a chance some people may read your posts and act on them...

Like running 1.95bar on (possibly) stock twins.
Mapping ignition timing using the knock count on the power fc
Limited use of wideband? WTF!

So anyways, my thoughts are that my map was really on the razors edge - a map that a race car would use
Race cars dont melt down from mapping

I actually spat my tea over the screen after reading about the water injection, please take it from me it isnt water injection you need :)

I actually feel bad for you as you need to learn somewhere i suppose, do yourself a favour and pay someone to map your car and then have a little play here and there afterwards. Its the best way to learn the basics.
Learn about subtle changes first and effects they have, this will give you a better understanding and make it easier to move on.

Cheers

Rob
 

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Race cars dont melt down from mapping
Cars terminally fail from 2 things only really, oiling issues, and det issues.

The crazy high PCPs that det causes is what blows head gaskets etc etc.

Very rarely from reaching the true strength limits of a component is all was running correct.
 

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Discussion Starter #10 (Edited)
ok, so how do **you** map ignition timing? It can't be rocket science. Knock, EGT, AFR, all taken together - am I missing anything? Experience of course, but there is literally not a soul in this godforsaken country who'd I'd trust to map my car any better than I could. It's either send my car to Japan, import a tuner for a few days, or DIY. And I'll be honest - I want to be able to completely map a Power FC. To me, that will be as much an accomplishment as anything else with Skyline ownership, including driving. So I blew a block. I could smash one of my guitars on stage and be out the same amount. But dammit, I really want to figure out, learn, know, and master the RB26DETT. I feel like Luke Skywalker in Empire Strikes Back - I've learned so much from when I bought the car, yet I still don't know shit, rush into it prematurely, and I get ****ed up by the Det Side :p

I ran my map for two months under all kinds of conditions, driving the car every single day, to work and back, drag racing, high speed WOT fukitall wangan runs, drifting, late night drive it like I stole it sessions, basically flogging my car slightly, then harder, then mercilessly, as I gained confidence in the car's map. I do have to wonder why the car would take all that without a whimper, then melt down completely due to a failing fuel pump at a cruising 140kph with 160kph peak, 1/4 throttle, ten minutes after starting from home and no shenanigans except just highway driving the way a Skyline does so well.

Be honest though - I have prejudiced the thoughts of many here by that 2 bar stunt, perhaps including yourself. I had to know, and you're wrong about one thing - unless the forum reader is a true moron, most noobs will read my posts and avoid the same action like the plague. In a word, I do truly idiotic things, I am certifiably a bit mental, yet I don't think that's what killed my block. Someone please prove to me otherwise with specifics.

SO, one possible explanation could be that the failing fuel pump had the car running extra lean, long enough to send the EGT through the stratosphere, and the rings just melted through. Which would exclude both the turbos and the car's map as primary causal factors.

Someone thought piston ring land damage cause by the 2 bar stunt led to piston ring failure. Yet extremely close inspection of all six pistons shows that the rings simply melted in place, are still exactly in place, and the lands, barring x-ray microcrack searches, look fine. I've seen an RB26 that blew due to detonation - the piston rings were bent and yanked out of the piston lands. I thought my engine was seized. Actually, that was the sound of an engine turning over with zero compression - quite easily, in other words!

Had I EGT gauges, or had I replaced my fuel pump when I should have, would this still have happened, due to mapping errors?

If my map was truly off, wouldn't my engine have blown from detonation while running sustained 1.4bar boost, racing around, gunning it to 8500rpm in every gear, for a good solid ten minutes? Or if my fuel map was off, wouldn't that give plenty of time to run extra lean and melt my innards via high EGT during some very spirited driving? Somehow, my car took all those hard runs and with nice long cooldowns, didn't show a sign of faltering until the fuel pump failure, which just happened to coincide with my sudden, instant, catastrophic piston meltdown.
 

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Copper pipe bolted to the head. Needs to be approx 15mm*150mm. Flatten the end and drill a hole. Stick a length of fuel hose in the open end, stethoscope the other end and your away. A nice `upgrade` is frequency filtered knock/microphone into PC. This has been covered before (Hugh, I think, posted an excellent link).

You can hear the onset of knock quite clearly, mid-load from 2000ish rpm upwards. This is the BLD timing (roughly!). A degree or two more and you will start to hear clear knock events. High rpm is more tricky and your likely to only pick-up on actual knock events rather than BLD.

Given a dyno P&E cell, and 64 external channels to log through it is very easy to find the optimum boost,cam, spark, AFR etc etc. I dont have one of those (at home anyway!).
 

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Maybe something you need to also consider is reading some books.
Rob's advice on reading books is the best you can get - the same goes for any component on the car (suspension, brakes etc).

There are a load of people who have made all these mistakes for you and it's just silly or arrogant to ignore that. Engine workings are a LOT more complex then you would believe - I have a MIT book with over 1200 pages just on cylinder design alone :(.

Start with A. Graham Bell's Forced Induction Performance Tuning...

Amazon.co.uk: Forced Induction Performance Tuning: Bk. H691: Books: A.Graham Bell

Graham's book also explains the reasons for the damage that can occur and what to look for to give you a clue about the real cause.

I feel empathy for you as it must be gutting to have the engine wrecked like that :(.

It may have been a fuel pump - it's simple - if the pump still works it's not it.

Damage can be caused over time until one component has a sudden failure resulting in it looking for all the world like just a sudden problem out of the blue, the infamous "Everything was great for months then bang" line. Running 1.4 bar on standard turbos will cause a great deal of heat in the intake which in turn lowers the octane rating of the fuel a great deal and over time the heat causes all sort of fatigue problems and may have ended up in a valve glowing hot enough to pre-ignite the fuel.

Cylinders do run at different temperatures especially if the manifold isn't a great one (once again Graham's book explains all this in detail) - I believe the first and last cylinders (depending on engines) are the main problems.

There is also a difference between det and pre-ignition. Det wears the engine down over time and normally happens at WOT etc while pre-ignition (the real killer) happens at low throttle as to pre-ignite the flame to move it needs low pressure in the cylinder which it gets on low throttle after a short gunning run followed by easy driving.

A simple overview is here TTM TECHNICAL | Forced Induction - Detonation and PreIgnition

I would guess that as everything melted you had pre-ignition not det probably due to something glowing that shouldn't have.
 

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Discussion Starter #13
I can't thank you enough for those links. I'm sure I got fried by pre-ignition - it blew at low throttle after a short blip up to 160kph - just as you describe. I would have never guessed. Some studying, and I'll figure out what was glowing...the entire head? :p

The fuel pump was dead, still is dead, just one dead pump.
 

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`Running 1.4 bar on standard turbos will cause a great deal of heat in the intake which in turn lowers the octane rating of the fuel a great deal ` - Fuel octane rating does not change with intake air temp!!!! High intake air temp certainly can drive more knock, for which a higher octane fuel may help...And given a decent intercooler the charge temps would not be that high anyway.

`believe the first and last cylinders (depending on engines) are the main problems. ` This absolutely depends on the manifold design, no generalizations are really possible.

`There is also a difference between det and pre-ignition. Det wears the engine down over time and normally happens at WOT etc while pre-ignition (the real killer) happens at low throttle as to pre-ignite the flame to move it needs low pressure in the cylinder which it gets on low throttle after a short gunning run followed by easy driving.` You are highly unlikely to suffer from PI when under steady-state low throttle openings. PI is most likely to happen during full throttle, when the piston is approaching bottom dead center on the exhasut stroke. Also `det` is quite capably of destroying an engine in a single cycle. One 30bar knock event can quite easily break a ring-land or crack a top ring.

Beware what you read in books!!!!!!!
 

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Discussion Starter #15
my intake temp (according to the PFC peak values) was 24 degrees when I went through preignition meltdown. I wouldn't call that particularly hot.

The #6 cylinder is the lean cylinder on the RB26, so I've heard. Apparently the Nismo intake plenum tries to address this. I wonder how those giant JUN or Greddy intake tanks help/hurt/affect things.

I just suddenly had surging extremely high cylinder temps - no evidence of high pressure knock. But I do have the feeling that my map was very close to BLD timing. Very, very close. I wish I had full time EGT and wideband before (my Apexi gauges are on their way, ordered *before* meltdown, and my NTK wideband lambda just arrived), but I do have a very good sense of the effect of ignition timing on knock and response. Pity I have to wait until after my engine is rebuilt before I can properly map the fuel curves (with EGT and wideband datalogging), but would a safe fuel curve have saved me from the failing fuel pump?

In other words, why can a fuel pump fail on a factory built turbo car and not meltdown the engine? How dramatic the safety margins built into the maps they must be!
 

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running lean can kill pistons...i done it to mine when the fuel regulator hose came off

if what some of the reasons here for your failure is true then your pump issue would have to be a coincidence lol, a bit unlikely eh........

listen to your mechanic ;)
 

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The intake air temp sensor is 6mm on the RB26DETT. It is not going to show you the instantaneous real intake air temp. It is only really useful as a `bulk` offset to indicate if its a hot day or not.
 

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Discussion Starter #18
running lean can kill pistons...i done it to mine when the fuel regulator hose came off

if what some of the reasons here for your failure is true then your pump issue would have to be a coincidence lol, a bit unlikely eh........

listen to your mechanic ;)
which one :p like feuding sisters, they're arguing with each other bitterly.

wouldn't pump failure have much the same effect as losing a fuel hose? were all six of your pistons FUBAR?
 

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Discussion Starter #19
The intake air temp sensor is 6mm on the RB26DETT. It is not going to show you the instantaneous real intake air temp. It is only really useful as a `bulk` offset to indicate if its a hot day or not.
I had thought of having an intake temp gauge put in, but felt it redundant as I was getting that info from the PFC. But if it's vague, where would you put the sensor to get instant real-time info? Or would an "upgraded" sensor in the same location on the intake plenum give more real time info?
 

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You`d put it in the same place but use a 0.5 or 1mm sensor. You would not use it for mapping however. I only used it to establish compressor and intercooler efficiency. The std sensor is fine for its intended use.
 
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