Warning for GTB owners...

[hutchysrs50]

Again, like Steveopc with his mdx hybrid I think he said.

[alex_e3]

Ah yes, the combined gas equation for a perfect gas! It's been a while!

I get you now though.

Sent from my D5503 using Tapatalk

[silky16v]

Exact same damage as mine, but my polo went running nozzles abet I was running 2.6bar or trying too anyhow

There is a sweet spot of maximum boost pressure on the 2260 and making sure you don't try fed too much boost in too soon like I said use fuel to make the turbo spool to avoid compressor surge!

Generally gutted for you guys losing engine but I hope now you will be buying race nozzles and avoid this engine failure

It would be nice for you guys to stick with stock engine as I guarantee you will be surprised how much quicker they are with nozzles and mapped accordingly

[faboka vrs]

It's caused by having to start the injection too early in order to achieve the necessary fuel delivery quantity through a longer duration, so it's a bit like detonation, the piston hasn't travelled far enough before combustion starts and the excessive pressure cracks the piston or the head or blows the gasket if it can.

Start of injection hasnt been increased anymore than a basic remap as theirs no way to monitor combustion pressure. This does mean end of injection is later.

2000rpm = 7 degrees ATDC

2500rpm = 9 degrees ATDC

3000rpm = 13 degrees ATDC

3500rpm = 17 degrees ATDC

4000rpm = 19 degrees ATDC

4500rpm = 17 degrees ATDC

5000rpm = 15 degrees ATDC

Comparing end of injection to a 2.0 16v pd170 with a stage 2 (hate stages) remap running 42 degrees of duration.

2000rpm = 21 degrees ATDC

2500rpm = 21.5 degrees ATDC

3000rpm = 23.5 degrees ATDC

3500rpm = 24 degrees ATDC

4000rpm = 22 degrees ATDC

4500rpm = 20 degrees ATDC

Edited 19 February, 2016 by faboka vrs

[sepulchrave]

Surely you mean BTDC for SOI and ATDC for EOI?

[faboka vrs]

Yeah. The numbers I posted are how far the injections stop injecting after top dead center. The graph just shows degrees not specific to BTDC or ATDC.

Duration is degrees length.

SOI is BTDC

EOI is ATDC

Edited 19 February, 2016 by faboka vrs

[sepulchrave]

Ok, this is interesting because if we want to retard the ignition point then logically we must begin SOI later than normal, but what you're saying is that this isn't possible with standard injectors because the EOI must be extended to allow sufficient fuel to be injected.

Therefore if we were using uprated injectors we could retard the ignition point and still inject enough fuel for a complete burn, so given the very high cylinder pressures and temperatures in a GTB equipped engine we can indeed move the SOI to be later and still get a complete burn with uprated injectors.

Do you have similar numbers available for SOI? All the evidence is pointing to ignition starting too early and over pressure bursting the cylinder at the weakest point which should be the head gasket, but with uprated ARL bolts and MLS gaskets we've found the limit of the standard pistons instead.

[devonutopia]

I'm not sure if I am just lucky or my bottom end is a ticking time bomb...

[sepulchrave]

I'm not sure if I am just lucky or my bottom end is a ticking time bomb...

 

Or maybe you're sufficiently retarded...

[coskev]

So we've got ;

a hybrid car running 2 bar,

Two 2260 powered running 2.5 bar on standard injectors,

And a 2260 powered one running 2.6 bar on bigger nozzles,all cracked Pistons.

So IMO these are all highish mileage engines that are being asked to handle way more boost/heat/power than the standard Pistons were ever designed for,you will get failures

The thread title needs changing I think Alex

[Titanium_Man]

This thread has made me rethink my plans of turning my power up. Currently running only ~ 1.7 bar with the potential to increase to ~2.4 (according to the last mapper of this turbo)

Hmmmmm ......

[faboka vrs]

So this is Southy's but displayed a little different in case people are finding the graph hard to read.

 

- = BTDC

+ = ATDC

 

Duration is just length the injectors are open for in degrees crank.

 

Fitting larger nozzles allows us to run reduced duration and also reduced start of injection (retard the ignition so to speak).

Edited 19 February, 2016 by faboka vrs

[faboka vrs]

Added a couple of other graphs and setups for people to look over. All mapped by me apart from the other tuner graph.

 

Dont ask me who's it is as I wont tell you

[devonutopia]

Or maybe you're sufficiently retarded...

 

I can't argue against that.  I pretend to know but in reality I leave it to the experts to do the programming work.  I just give it the abuse!

[sepulchrave]

Then that's the answer, the SOI is too early.

 

For a given compression ratio, say 25:1, the cylinder pressure at 1 bar (no boost) is 25 bar but at 3.5 bar (full boost) it's 87.5 bar and the temperature will also be much higher. This results in greatly increased combustion speed since flame propagation is much faster at higher temperatures and pressures.

 

So in order run higher boost we have to retard the ignition point or cylinder pressures will become dangerously high as the engine speed increases due to the increased turbulence speeding combustion even further, the standard injectors don't have the headroom to allow for this so uprated injectors must be used beyond a certain boost level. A realistic limit is probably ~2 bar at which point the standard head gasket and bolts tend to start to fail, putting the stronger ARL bolts in is like putting a higher rating fuse in an electrical plug because the standard fuse keeps blowing. It's not solving the problem, just moving it to another component.

[stevobeavo]

What was BossFox running in his SE I know I was 260bhp but unsure of his setup.

I know the new owner had some form of engine problem with that.

[silky16v]

So we've got ;

a hybrid car running 2 bar,

Two 2260 powered running 2.5 bar on standard injectors,

And a 2260 powered one running 2.6 bar on bigger nozzles,all cracked Pistons.

So IMO these are all highish mileage engines that are being asked to handle way more boost/heat/power than the standard Pistons were ever designed for,you will get failures

The thread title needs changing I think Alex

 

I wouldn't say miles has got anything to do with it my Fabia been fine for 15,000 miles and on 118,000 and been modified before i got it with a hybrid for 4 years

 

It mapping/high duration and too much boost!!!!!!!

 

Thread title should read "don't run a 2260 on stock nozzles and chase bhp"

 

sorry that might sound smug but i've waiting for all these engine on stock nozzles to blow up as i knew it would happen sooner or later!!!!!

Maybe now people realise that race nozzle are fitted for a reason and 230-240bhp is absolute max bhp you can rinse outta stock injectors if you want reliability 

 

I was one of 1st on here with engine failure (polo GT) and i did do the daft durations on stock injectors (Fabia), but very quickly did a U-turn and fitted the nozzles and then remapped from Kris@ http://www.dieselpowered.co.uk/ as they was simply no one else with as much mapping and dyno time as him in this country when it comes to GTB2260 on race nozzles!

Edited 19 February, 2016 by silky16v

[silky16v]

So this is Southy's but displayed a little different in case people are finding the graph hard to read.

 

- = BTDC

+ = ATDC

 

Duration is just length the injectors are open for in degrees crank.

 

Fitting larger nozzles allows us to run reduced duration and also reduced start of injection (retard the ignition so to speak).

 

fuk the SOI on that 2nd graph is dangerous and must have smoked its absolute **** off but compensation is given as EOI is very low

 

28 should be the limit and 30+ if you don't mind pushing it and no fussed about engine maybe letting go

Edited 19 February, 2016 by silky16v

[silky16v]

What was BossFox running in his SE I know I was 260bhp but unsure of his setup.

I know the new owner had some form of engine problem with that.

 

 

this was JabbaSport but i believe they run Water/meth injection to compensate for the shortfall of the stock injectors

[sepulchrave]

Silky's right, miles are irrelevant, the stock piston is inherently weak because of the chamber in the crown so the tune must work around that weakness, if you upgrade the head bolts the piston or the head casting will fail instead unless you retard the ignition point using the headroom uprated injectors will allow.

 

I would say 220-230 BHP is your lot on stock injectors and since there are no stronger pistons available then you MUST upgrade the injectors if you want to run big boost.

 

But then I've been saying this for years and nobody listened. So, meh.

[faboka vrs]

Why quote bhp as the limit when really the limit is boost and duration. You can still have X bhp combined with long duration. Result is unburnt fuel and increase in EGT. So still the "safe bhp" but unsafe duration.

[faboka vrs]

fuk the SOI on that 2nd graph is dangerous and must have smoked its absolute **** off but compensation is given as EOI is very low

Very long duration for bigger nozzles isn't it. The duration I'm running on kevs is very close to stock pd150.

The original 215bhp limit for stock nozzles came from the theory of EOI being around 7 degrees ATDC. People said running past this will result in increased smoke and EGT. This theory I believe is wrong as you still make power past 7 degrees without EGT increases. EGT increases when your not burning the fuel.

[silky16v]

Why quote bhp as the limit when really the limit is boost and duration. You can still have X bhp combined with long duration. Result is unburnt fuel and increase in EGT. So still the "safe bhp" but unsafe duration.

 

true yes but i was speaking relatively as a known given that stock nozzles on what ever bigger turbo setup are at there limit at 230-240bhp

 

yes you can do do 260bhp but daft duration so not safe back the durations and boost back and you will get to around the 230-240bhp level (using a 2260 as example)

[sepulchrave]

Why quote bhp as the limit when really the limit is boost and duration. You can still have X bhp combined with long duration. Result is unburnt fuel and increase in EGT. So still the "safe bhp" but unsafe duration.

 

Because BHP is directly proportional to boost, it's only a guideline and although there are many small mods that can be made to increase BHP without increasing boost any further, fuelling is still the dominant issue, if the injectors have no headroom then no more power can be safely found. Devonutopia hasn't smashed a piston because he's using big injectors with enough headroom, but he did crack a head IIRC and he certainly had headlift a while back.

 

Turbos get mullered by high EGT, engines get mullered by detonation, and all the pistons shown in this thread have been smashed or melted by detonation, head cracking as well, head lift is an early warning of excessive cylinder pressures, if you fix the head lift then something else has got to give instead.

 

Edit: Look on the bright side, stronger crank and rods are definitely not necessary if a piston can pop like that with no damage to the bottom end.

Edited 19 February, 2016 by sepulchrave

[silky16v]

Very long duration for bigger nozzles isn't it. The duration I'm running on kevs is very close to stock pd150.

The original 215bhp limit for stock nozzles came from the theory of EOI being around 7 degrees ATDC. People said running past this will result in increased smoke and EGT. This theory I believe is wrong as you still make power past 7 degrees without EGT increases. EGT increases when your not burning the fuel.

 

we know now the limits of stock nozzles you can take SOI to 28 and EOI to 10-13deg safely but this is still a lot of duration & will have some level of smoke

 

its like the difference between no smoke and smoke the same car feels much quicker with smoke (added fuel in correct part of the map)

Edited 19 February, 2016 by silky16v