Serious question about DET....

I am running in first/second gear around 2bar boost and in third a peak of 2.4 tailing to 1.9 bar and in 4th/5th 1.7bar flat........now i am using det cans but i aint sure of what the noise is really...i cant seem to hear anything unusual......right now i running a Collins ignition curve which seem quite advanded compared to the original base map....now with 7.9-1 and plenty of advance why will it det???thru heat??????..So if i make it run say 11.2 afr very rich will that cool it down enuuf not to det thru heat and where would the det really occur in 4th 5th gear only????

 

surely det is most likely where the cylinder pressures are the greatest no?

sorry i know i aint a tuner or stu but i feel compelled to read the ima life story of tuning thesedays

 

Phil, There are 2 answers to your question from my limited experience...

1) Try it until it melts.

2) Measure the EGT on a long high boost run to see it det/high temps start
to creep in over a period of time under high load.
(This is where engine dyno's are usefull)


On a recent 630 bhp engine done on my ecu, the mapper ran the engine
for 10 minutes on the dyno on full boost at peak torque to see how the EGT's and
other temperatures progressed.

Cyclinders/pistons/sparkplug/valves can all accumulate head under prolonged
boost conditions and although its ideal to tune an engine on the det limit,
often most tuners have a feel for what margin of safety is included in
the final map.

E.G DET=11 degrees, NO DET=10 degrees, SAFE=8 degrees (but slight power reduction)

The safety margin size depends on many factors beyond my knowledge !!

 

Cheers Simon,so basically the issue is gonna be HEAT so in theory its not in 3rd long enuff to suffer it i guess but 4th/5th it could melt but then again its only running 1.7bar by then..........BUT then doesnt heat mean a weak mixture???So would the AFR's lean out?

I can see tuners dont want to divulge

 

It's NOT just heat - cylinder pressures play a massive part .

And you having high compression will have to be particularly careful of excessive cylinder pressures .

The only thing to do is FORCE your car to det so you recognise the sound. However, this is VERY dangerous for someone as clueless as yourself , as it may already be detting it's tits off and you are not able to recognise the sound from all the background noise going on .

 

leanness will add unnecessary heat. but heat can be caused by many factors... you can still run a good AFR and melt things

 

as well as hearing det, is it also not possible to detect by a rising egt on the same afr?

i mean: if det occurs, the in cylinder temps will go up. and as the in cylinder temps go up, det gets worse

i would advance the ignition at low load conditions until you hear det and know what it sounds like.

and i would get some proper det cans and not just a shonky bit of tube

 

Detonation in any engine can be caused by a number of things Phil.

1) Excessive cylinder pressures:
This is created by having the maximum PCP earlier than 10deg ATDC. This is of course why we have an advance curve in teh first place, to keep our PCP around the 10 - 20 DATDC area under all conditions.

2) Excessive heat:
Cylinder head and combustion chamber temps can give rise to detonation and far more damaging "pre ignition" (Pinking as you know it) This is simply due to reaching what is in effect the fuels flashpoint.

3) Wrong or poor fuel:
As above, we want a fuel that burns slowly otherwise we will again exceed the PCP target area and cause massively excessive cylinder pressures that will blow holes in things. (Yes, optimax will burn SLOWER than say, sainsburys crap)

4) Excessive advance:
This again is a PCP issue and the first clue you will have is she will feel probably her fastest ever... then boom

5) lean mixture:
Lean mixtures = hotter burn, again taking us across and back to the heat problem. Lean mixtures also burn and flash faster so taking us to the pre PCP area problem.

6) Excessive EGT.
Often created by a combination of teh above. This will put excessive heat into the exhaust valves with corresponding heat and pre ignition problems as desribed above.

7) Excessively hot/cold ICT.
Hot and cold air has an effect on ICP and also AFR. We need to richen as the air cools and lean off as it gets hot. Failure to do so will make our advance curve WRONG. Beware.

Detonation in an engine is usually very slight. A very slight problem will only usually kill an engine if it occurs for a sustained period. So if we have say, det at 5500rpm (common for YB).
In 1st gear flat out she spends maybe, what? 1/4 second there?
In 3rd gear flat out she spends maybe, what? 1.5 seconds there?
In 5th gear flat out she spends maybe, what? 5 seconds there?... Boom.

Thats all for now Phil... hope it helps somewhat.

 

All these initials Stu. You haven't helped him one bit!!

He won't know his A.R.S.E from E.L.B.O.W!

 

ok ICP? PCP

i thought PCP was a drug?

 

I C P = In Cylinder Pressure.

P C P = Peak Cylinder Pressure.

 

ECP?

LPR?

LPD?

TCP?

WYSIWYG?

YWKLSTYEY?

 

Thanks Stu..appreciated!!!! So basically use Optimax only and stay out of 4th and 5th gear So tell me is a stage 1 ign map the same as a stage 3 at a certain comp ratio and the same boost pressure???....Also at what boost pressure on say my engine will too much advance REALLY fuck the engine in 4th/5th any boost or over a certain point?

Its funny Daz cause you say i am dumb even you Mike(although your just a twat and what you say dont count )...but atleast i am HAVING AGO ..instead of just saying the person doin it aint capable...i'd rather have a go than just read about it ...as i have said many times before..with a little help from your mates in the know anything is possible!

 

 

Phil,
I just like taking the piss out of you at EVERY available opportunity, so just ignore me .

 

VEr clear clear explanitiaon stu...

want a job at BMW teaching?

alex

 

well done boschy keep it up

 

spiky, is that all you can do? try n get the rest of em (no googling! )

 

PCP, thats about the only relavent thing here as i think thats what IMAs on with some of his posts

IMAs on the Angel Dust

SERIOUS! Read this, most the effects explain him perfectly

Phencyclidine (PCP) was developed in the 1950s as an intravenous anesthetic but, due to the side effects of confusion and delirium (which explains why he thinks he can live map as good as a pro with no previous experience ) its development for human medical use was discontinued.

Detached, distant, and estranged from their surroundings (Hence why "its not his scene"

Numbness of the extremities and loss of coordination (Explains why hes shat himself over the power as its too much)

sense of strength and invulnerability (How he seems to drive and map at the same time, with only a rottweiler as help)

Users of PCP report difficulties with learning (Does he EVER listen to advice? )

HERES THE BEST BIT!

In some users, PCP may cause acute anxiety and a feeling of impending doom; in others, paranoia and violent hostility, severe mood disorders, and in some, it may produce a psychoses indistinguishable from schizophrenia Sound like anyone off here?????

 

 

Steve i can see what you use

LSD

Makes the user hallucinate things that arnt real...(Like all the women you shag and your mega power R32)

 

@ steve

 

Dont be dangling tasty carrots like that one in front of me. If i thought i was good enough to do your job id say yes pal...