I just had little drive with my car and did some tuning with it. Some details: I have basically standard Escort cosworth engine, aftermarket ecu, Holset turbo, standard compression, etc. I made myself some headsets (to listen for pinking) and plugged the pipe near engine. I first did a run with 1.2bar boost and about 10degrees ingnition advance. No pinking. Then I adjusted 15degrees of advance, and still no pinking. I then raised the advance to 18degrees and as soon as boost went up about 4000rpm it started to rattle, don't know what to call it, but it wasn't actually yet pinking, it was just starting to if you know what I mean My point is that does the engine usually pink more easier when the engine makes peak torque? Since the 4000rpm could be the point where my engine makes the most torque. I must try later to adjust more advance after the peak torque and see how it works.

 

that 'rattling' that you are hearing is called det.

if you dont know what you are doing you WILL kill the engine mate

 

best thing to do is set a high ignition advance at lower boost or just as it comes on boost get used to hearing the pink then go for load as fudge as stated u will kill the engine

 

It seems that you are not very much diy people in here I do know that the detonating makes holes to the pistons, but atleast I have good reason to buy new ones Okay, I'm just joking. I do wan't to keep my engine in one piece. But what was the answer, does the engine tend to detonate easier when it is making its peak torque or not?

 

What else is likley to make a pinking noise when coming on boost?

 

Or is just that the ones that do know about engine tuning and detonation wont tell (tuners like Ahmed, Stu, etc.) and the others don't really know anything about it. Is there any book or webpage that discusses about this thing?

 

it can happen anytime inwhich PCP (peak cylinder pressure) is too high!

of cause the more VE you have... the easyer it will happen

 

radio interference from the alternator coming though your speakers!
needs more suppressors

 

 

just after an hour,,, time too get shirty

remember if the forum was just a "ask the expert" place than i think it would be pefectly boring its about discussing issues,,, then the experts come in and set us all straight

 

Okay I must make one thing straight. I did not mean to be shirty. It could just be that since my english isn't that good, I can't always write my toughts in here like I should have So my apology. It's just that this is one of those things that I'm very interested at. So every information and details are well appreciated.

 

yrkesman


dont worry dude,,, i was on teasing

 

so try what i said ! back to ignition off ten pick a area on the table where its low boost about 6 psi or even without boost keep raising the ignition slightly till it pinks then you will here it properly so you arnt missunderstanding the sound the try building the table up

 

I think that the sound I heard was quite obviously pinking/detonating. I did few runs to the redline with lower advance and it didn't make any noises. But I'll do some more testing and tuning on weekend when I have time. The final tuning will be done later on a dyno.

 

To answer your question… YES, an engine is more likely to ping/pink/Det at peak torque as this is the point of maximum Cyl pressure. Also 18Deg of ign advance at 1.2 bar boost does seem too much for pump fuel/stock compression (I assume your using pump fuel).

 

i thought this ! but my engine is 7.5 comp and i run a lot more ignition @ 27 psi

 

Realistically there are a number of things that will determine the tolerance of ignition advance. Obviously the compression as well as the fuel quality from county to county. Not to mention exhaust gas back pressure based on turbo spec, squish etc etc.

From a tuning point of view if the engine had no sign/noise of Det and 3 deg of advance was increased and you had what sounded like Det, there is a good chance it is Det.

The correct method would obviously be to tune on the dyno and have the least amount of ign advance for the most amount of torque. This is better known as “MBT” (mean best torque).


Jaycos,

Can you find out exactly how much advance you have at 27psi? Also what brand fuel (Shell, BP) do you use? This will give me a better idea if the fuel you guys have there is of better octane/quality than the piss we have down under.

 

I run 98ron standard pump fuel, the turbo is Holset HX35 (54/60mm wheels with number 10 exhaust housing) and I have 3" exhaust. So I'll try some more advance after the peak torque and we'll see how it works

 

If your “street tuning” I would leave the ign timing figure constant from peak torque to peak hp/red line. Once on the dyno you can then see what difference there is in power output based on the advance you feed in with rpm.

Bear in mind that you will be tuning at a certain charge temp on the dyno. Once the base ign table has been completed it is worth turning the fan off on the dyno and use a hose to stabilise the engine water temp by running the water over your radiator but this still allows the charge temp to increase. By doing this you can then tune the “correction map” that removes ign advance as the charge temps increase other wise there is a high chance of det when in mid summer or racing at a track day for instance.

 

right just realised that my sensor offset is 10 degree out so on 97 ron at max torque power 16 degree at 2 bar of boost

 

jaycos

TUT TUT

 

 

Sorry mate, is that 16 deg or 6 deg at 2 bar boost? If it’s 16deg then you guys must have much better fuel than what we have here. If I were to run 16deg of advance at 2 bar boost you’d be able to hear it det from a mile away

 

Oh, forgot to mention, another aspect to think about is the A/F ratio too. A richer mixture will also tolerate more ign advance before det.

 

Here's a comparison of my old T34.63 and the Holset I currently have

http://www.saunalahti.fi/~jatuomo/Es...a/IMG_2505.JPG

The Holset I currently have is actually quite small compared to the ones most of here in Finland use.

 

I have used 12-12.5AFR on 1.2bar boost. I might take it little lower when upping the boost to 1.5bar.

 

the way i find best to listen for det, (using det cans)

is using the brakes to hold the engine @ a set rpm (normally peak torque/boost) and use the throttle to bring in full boost, and if you suspect det, back off the throttle slightly, and if it goes then you know its Det.

 

Your AFR sounds right. I normally run 12.0 once over 1 bar boost and dip into 11.8 once over 2 bar boost. Remember that the measured ARF at the tail pipe is the “average” of all 4 Cyl’s.

Before I tune any serious engine we normally remove all the injectors and have them flow tested to make shore they all flow the same amount. If you do find an injector or two that flow 1-2% more than the rest I normally fit these to Cyl’s 3 and 4 as these Cyl’s will be the fist to lean out in the event of a failure on a high boost YB.

 

300kW and 540Nm at 22psi. The boost just didn't rise as fast as it normally does on the road. So the real torque should be more. The boost rises about 1000rpm sooner on a road than on a dyno, but still I'm quite pleased. The fuel mixture was too rich and the ignition could have been better, since I didn't have time to prepare it enough. The engine is also totally standard so there is lots of things to improve. I'll have to order vernier pulleys, new cams (cat cams propably) and get the head flow prepared. Then well see how it should work