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Engine pinging when hot - OK when cool #95824
07/10/06 4:18 am
07/10/06 4:18 am
Joined: Feb 2006
Posts: 767
Central Otago,NZ
G
Ginge Offline OP
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Ginge  Offline OP
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Joined: Feb 2006
Posts: 767
Central Otago,NZ
My '71 T100C pings when it is working hard (up hills or on 65mph freeway runs into a slight breeze). It also struggles to hold revs in top gear when high in the rev range when climbing.

It only does it when it is hot. If I stop for 20 mins or so for a beer or let it cool (down the other side of the mountain) it will behave again, and starts to pull again.

New AMAL 626 with standard jets and slide. Running highest octane fuel i can get (98 I thnk)

I don't think it's a timing problem as I can't purposely make it ping by working it in low gears.

Is this a symptom of a lean mixture?



'51 C11 in a '54 C10L frame..."The Bantam Eater"
'70 Triumph Trophy 500. Bottom end rumble awaiting diagnosis
'72 Triumph Tiger 650. Getting a new wiring harness
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Re: Engine pinging when hot - OK when cool #95825
07/10/06 6:14 am
07/10/06 6:14 am
Joined: Jun 2006
Posts: 52
Z
Zorac Offline
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Zorac  Offline
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Joined: Jun 2006
Posts: 52
sounds very much like its lean, i would fix your jetting and then switch to low grade fuel (lower octane) assuming your engine is stock

Re: Engine pinging when hot - OK when cool #95826
07/10/06 12:41 pm
07/10/06 12:41 pm
Joined: Jun 2004
Posts: 408
Columbus, Ohio, 1978 T140E
T
tomterrific Offline
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Joined: Jun 2004
Posts: 408
Columbus, Ohio, 1978 T140E
Don't run a lower octane fuel! That is a good way to get a holed piston.

As to why the engine is pinging:

Check the darn timing. There are few ways to make an engine detonate easier than over advanced timing.

What plugs are you using? You are working that little engine hard and probably could use a cooler heat range spark plug, like B8ES or Champion N3C.

More fuel will cool the charge. Lift needle and/or increase main jet size.

You don't have a dumb tool bag blocking the air flow to the head?

Are you sure the engine is detonating? Look at he plug tip using a magnifying glass to see if there are little white specks present. These are tiny molten blobs of aluminum blown from the top of the piston when detonation scours the boundry layer of insulating gas from the top.

I started to use 15W-50 Mobile One and I seemed to detect cooler running. Maybe I got fooled but the entire engine does seem to leak now and was tight before the Mobile One. Some good, some bad.

And lastly, have you ever thought about slowing and giving the little engine a break?

Tom Graham

Re: Engine pinging when hot - OK when cool #95827
07/10/06 2:01 pm
07/10/06 2:01 pm
Joined: Mar 2005
Posts: 10,232
Boston, Massachusetts
J
John Healy Online content

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John Healy  Online Content

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Joined: Mar 2005
Posts: 10,232
Boston, Massachusetts
Actually shifting it down to a lower gear when the bike stars to emit signs of pinging will also "give it a break!" It lowers the dynamic compression which will allow the motor to run cooler. The higher rpms also gives the combustion less time to start misbehaving!

This is falls under how I define "lugging" a Triumph. Read Panic's post on 'lugging."

These little motors love to be reved!
john


Re: Engine pinging when hot - OK when cool #95828
07/10/06 6:23 pm
07/10/06 6:23 pm
Joined: Jun 2006
Posts: 52
Z
Zorac Offline
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Zorac  Offline
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Joined: Jun 2006
Posts: 52
Quote
Originally posted by tomterrific:
Don't run a lower octane fuel! That is a good way to get a holed piston.
why do you say that?? i dont have a manual infront of me, so i may be mistaken, but i highly doubt it would reccommend an octane higher than low grade. there is no benifit to running a higher grade ocatane than required by the manual, always run the lowest grade reccommended by the user manual. the only things that will happen when you put in higher grade is youll lose hp, and youll pay more for gas. you will not get a hole in your piston running a octane your engine was designed for. but like i said before, i would continue running high grade until you have the pinging problem sorted out

but back on topic, i had a motard that did the same thing after i put a new carb on it, turned out it was leaning out at high rpms, a bigger main jet, and two notchs on the needle and i was good to go....

was your bike doing this with your old carb on? im going to assume that this started with the installation of the new carb, otherwise disregard and pursue some of the other potential culprets metioned by the other members here, my knowledge here is a bit lacking but im assuming the 926 is the stock carb for you bike as well?? if so id open up the old carb and the enw carb and make sure the jets, needle, clip position and what not are the same, make sure the carbs are of the same diameter, i know wiht the minikis you can get different size carbs with the same mounting flange, so you could accidently get a carb a couple mm smaller and it would still mount up fine

Re: Engine pinging when hot - OK when cool #95829
07/10/06 9:13 pm
07/10/06 9:13 pm
Joined: Jun 2004
Posts: 408
Columbus, Ohio, 1978 T140E
T
tomterrific Offline
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tomterrific  Offline
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Joined: Jun 2004
Posts: 408
Columbus, Ohio, 1978 T140E
Why high octane? Because when the T100 was manufactured we used leaded gas. A popular brand in the states advertized 94 octane regular, their lowest octane. Now 93 octane is high test pump gas here in Ohio and it only costs 20 cents more than the piston holeing 87 octane. Six full octane points for only 20 cents, just how cheap are we Brit Bike guys? We already know the bike is run hard and is detonating, on the verge of destruction. I stand by that if someone is running cheap 87 octane and they hole a piston, it is because they didn't spend 20 cents for high test.

Tom

Re: Engine pinging when hot - OK when cool #95830
07/10/06 10:04 pm
07/10/06 10:04 pm
Joined: Apr 2002
Posts: 710
Out There!
N
Nick Offline
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Nick  Offline
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N

Joined: Apr 2002
Posts: 710
Out There!
Forgive me if this sounds presumptuous, but if you're new to Brit bikes and have been riding modern bikes, you can't ride an old Brit-bike the way you ride a modern bike. Yes, the old bikes like some revs, yes you can ride them pretty hard, but if you treat them like a modern bike you're asking for trouble.


When people who should have known better cautioned me about the dangers of motorcycle racing, I always told them that a fear of death is nothing more than a fear of life in disguise.
Re: Engine pinging when hot - OK when cool #95831
07/10/06 11:08 pm
07/10/06 11:08 pm
Joined: Jun 2006
Posts: 52
Z
Zorac Offline
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Zorac  Offline
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Joined: Jun 2006
Posts: 52
in 1970, regular gasoline had a RON (research or road octane number) of 94, modern low grade fuel has an advertised at the pumps octane of 87, the 87 is measured by something called aki, or anti-knock index, which is generally 5 points lower than RON, meaning modern low grade is about 92 RON, only two points lower (so i guess an argument for mid grade could be made). in the 60s octane was generally lower, and crept up because of increasing lead contents, then in the late 70s its crept back down due to removal of lead, which then went back up in the 80s as they found replacement additives.

these engines were designed long before octane peaked, and with a relatively low compression, i highly doubt they required anything higher than lowgrade in their stock form.

i know my bonne is more than happy with low grade! :p

elevation can aslo have a very significant impact on octane requirements, the higher the eleveation, the less octane that is required.

i like to run the lowest octane possible without pinging to get the maximum hp and to save a bit of cash, its win win!

some links for reading in your spare time if you like!

http://www.faqs.org/faqs/autos/gasoline-faq/
http://en.wikipedia.org/wiki/Gasoline
http://en.wikipedia.org/wiki/Octane_rating
http://www.pcj.com/87Octane.pdf
http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm
http://auto.howstuffworks.com/question90.htm
http://www.ducati-upnorth.com/tech/octane.php

this is even better than the evergoing oil debate!!! laugh

Re: Engine pinging when hot - OK when cool #95832
07/11/06 12:08 am
07/11/06 12:08 am
Joined: Mar 2005
Posts: 10,232
Boston, Massachusetts
J
John Healy Online content

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John Healy  Online Content

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J

Joined: Mar 2005
Posts: 10,232
Boston, Massachusetts
The reaserch octane requirement listed in the owners manual for the 1973 T140 with 8.25 to 1 pistons was 97 RON. Most T140 owners have adjusted to US pump fuel with a few points lower RON.

There are many factors that enter to the octane requirement for a given motor. It runs from ambient air temperature, compression ratio, width of exhaust valve seat, condition of the rings, fuel mixture, camshaft overlap, ignition timing, intake valve closing, altitude, inlet air temperature, throttle position, load on motor, etc., etc.. Anything that will increase the dynamic compression ratio or increase the heat in the combustion chamber.

When a motor starts to ping or detonate you need to use higher octane fuel, which burns slower, OR correct the reason it is exploding and not burning. You either lower the static compression ratio, change your riding habits to keep the dynamic compression from getting too high, or find some way to cool the combustion chamber.

Changing the static compression ratio is a bit of a bother; using smaller throttle openings while accelerating, use a lower gear to make the gearing taking some load off the motor, or change the camshaft/camshaft timing; fit an oil cooler, increase the fin area, cool the inlet air through an air box away from any heat source on the motorcycle, ride at a higher rpm (less time for pinging to happen) etc.. Changing ones riding style can have a dramtic effect on pinging.

Elevation has an impact upon pinging because there is less air to be compressed, effectively lowering the dynamic compression ratio. It has the opposite effect of quickly opening the throttle while the motor is under load. When you open the throttle it lets in more air. With more air to compress the dynamic compression ratio increases.

Kevin Cameron has writen some very understandable articles about how to"Toughen your motor to detonation and pre-ignition." They are worth the read.

I wrote this with out any editing... need to go home and have some food...
john


Re: Engine pinging when hot - OK when cool #95833
07/11/06 1:09 am
07/11/06 1:09 am
Joined: Jun 2006
Posts: 52
Z
Zorac Offline
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Zorac  Offline
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Joined: Jun 2006
Posts: 52
i stand corrected!! i would of never though the manual would of reccommended an octane that high! my pinto of similar vintage never needed that! :p

kind of interesting actually, considering even super sport bikes have only required low grade until a couple years ago despite having compression ratios up to 13:1!!

i guess im going to have to loosen the grip on the purse stings at the pump!! :p

Re: Engine pinging when hot - OK when cool #95834
07/11/06 1:59 am
07/11/06 1:59 am
Joined: Mar 2005
Posts: 10,232
Boston, Massachusetts
J
John Healy Online content

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John Healy  Online Content

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Joined: Mar 2005
Posts: 10,232
Boston, Massachusetts
" kind of interesting actually, considering even super sport bikes have only required low grade until a couple years ago despite having compression ratios up to 13:1!!"

The bikes static compression ratio is only one of hundreds of factors that need to be considered when choosing a fuel. You must remember that a bike has what is called a dynamic compression.

Calculating the the dynamic compression ratio starts when the intake valve closes rather than at BDC as with the static compression ratio.

I like to use the term "dynamic" to describe cylinder pressure. I use it to describe the increase in cylinder pressure, over and above the pressure created by the classic definition of the dynamic compression, which is caused by things like: load on engine, throttle position, elevation, or other factors that effect the amount of pressure in the cylinder preceeding and during combustion. Anything that will incease the pressure the gas is exposed to increases the chances the motor will detonate.

In a return to an earlier parallel port design in the 1979 T140D, Triumph engineers were able to introduce more swirl in the combustion chamber producing a more even burn. This markedly reduced the combustion temperature to a point where they had to abandon Champion N3 plugs for ones two heat ranges hotter (N-5) to prevent plug fouling. In turn it lowered the octane requirement.

The examples go on and on, and all interesting stuff...
john


Re: Engine pinging when hot - OK when cool #95835
07/11/06 4:04 am
07/11/06 4:04 am
Joined: Feb 2006
Posts: 767
Central Otago,NZ
G
Ginge Offline OP
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Ginge  Offline OP
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Joined: Feb 2006
Posts: 767
Central Otago,NZ
All good comments, especially the octane info. For the record higher octane fuel helps rid the pinging but not totally. It pings worse on 91, often on the flat.

Haven't strobed the timing for a while, but I think I would know if it was off, and I try and run slightly retarded to avoid detonation anyway.

This is my third Brit Bike, and my second C range Triumph. During the last ride I had to watch the back of a 50's G3 Matchy disappear up the same hill while I changed down and let some traffic past. With an extra 150cc and T100C gearing I think I should have stayed with him.

The 626 is the correct carb, and replaced a 70's Keihin that was on the bike when I got it. I couldn't find a rebuild kit for it, it leaked and the banjo thread was stripped out. I checked the AMAL jets and they are as per manual.

I don't think it's my riding style, yes it gets ridden hard, but in the correct rev range, and in where the torque is. I've spent too much on this to break it, and I need it as a daily rider. Any sign of pinging or lugging and I ease back and change up or down as required.

I'll lift the needle a notch and see what it does.

Cheers



'51 C11 in a '54 C10L frame..."The Bantam Eater"
'70 Triumph Trophy 500. Bottom end rumble awaiting diagnosis
'72 Triumph Tiger 650. Getting a new wiring harness
Re: Engine pinging when hot - OK when cool #95836
07/11/06 5:21 pm
07/11/06 5:21 pm
Joined: Jun 2006
Posts: 316
Germany
KrispyKris Offline
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KrispyKris  Offline
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Joined: Jun 2006
Posts: 316
Germany
Wow...I cannot believe this was addressed before I had a chance to ask about it. Here in Germany, I was surprised to see 100+ Octane Benzine. The joy quickly faded when I learned of the RON rating system, which made the 100 octane rating convert to around 95, as in the States.

That said, my 2c

Running octane more than you need is a not only a waste of money, it actually hurts your performance. The physical charactaristics of higher octane fuel are simply to slow down/lower the burn rate in the combustion chamber. As the dynamic pressures rise, so does the temparature in the chamber. (Think about how a diesel works). The high octane fuels are formulated so that under these circumstances, the burn rate is controlled, not one of instant combustion.

As a result, running lower octane can actually improve performance, especially with lower compression (not static, but actual). What springs to mid is the farsical saying "I treated my car to Super..." Only winner was the Petrol Company. JK


BGL, Deutschland.
'67 Bonnie w/140V, '76 T160, '52 Vincent Rapide.
"Is that 'normal' mechanical noise, or the sound of imminent destruction...?"
Re: Engine pinging when hot - OK when cool #95837
07/11/06 11:18 pm
07/11/06 11:18 pm
Joined: Feb 2006
Posts: 767
Central Otago,NZ
G
Ginge Offline OP
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Ginge  Offline OP
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Joined: Feb 2006
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Central Otago,NZ
Update

Last night I pulled the carb and checked the needle which is as high as it can go. If I want to richen even further, is this a new needle and needle jet, or just one (or the other)?

Secondly,

The float level is way high. About .080 above the edge of the float bowl when pressing down on the tangs. Bike doesn't flood or leak petrol, so I left it assuming too high is not going to cause a lean condition. Is that right??



'51 C11 in a '54 C10L frame..."The Bantam Eater"
'70 Triumph Trophy 500. Bottom end rumble awaiting diagnosis
'72 Triumph Tiger 650. Getting a new wiring harness
Re: Engine pinging when hot - OK when cool #95838
07/11/06 11:58 pm
07/11/06 11:58 pm
Joined: Mar 2005
Posts: 10,232
Boston, Massachusetts
J
John Healy Online content

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Joined: Mar 2005
Posts: 10,232
Boston, Massachusetts
Yes JK, but the key to using lower octane gasoline understanding what you need in the first place and then adjust that figure for the "worst case scenerio." Or do install what modern cars have: a detonation management system.

It can take one or two engine revolutions to hole a piston. At 5,000 rpm that is 80 plus revs per second. By the time you figure out something is wrong the event is history and you are walking.

Your argument goes a long way with me when you are talking modern cars with knock sensing capabilities and computers able to shut the cylinder down, richen the mixture or retard the timing on the cylinder having the problems. I have been using regular grade gasoline in my cars for years. But a lot of the people on this site have done a lot to increase the chances they will expereince detonation. Taller gearing to start with, and I could add to this list, but supper is calling...

Giving octane advice to the average, untrained Britbike owner, I would sooner be on the safe side. There are a lot of people who are themselves capable of understanding the warning signs and make corrective action, but this is ability is rare indeed.

Who has thrifty Scotish heritage and spends wisely.
Sometimes being thrifty means spending a bit of money.
john


Re: Engine pinging when hot - OK when cool #95839
07/12/06 7:01 pm
07/12/06 7:01 pm
Joined: Oct 2003
Posts: 3,733
Emsworth, sunny south of Engla...
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dave jones Offline
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Joined: Oct 2003
Posts: 3,733
Emsworth, sunny south of Engla...
I normally use the 97 (650 Triumph) stuff but sometimes the 95. There is certainly no noticeable power difference between the two.

Re: Engine pinging when hot - OK when cool #95840
07/13/06 2:05 pm
07/13/06 2:05 pm
Joined: Jul 2006
Posts: 12
Blandford, dorset ,UK
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rolandgttuning Offline
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Joined: Jul 2006
Posts: 12
Blandford, dorset ,UK
Hi Guys, if you want maximum reliability AND performance, always use the highest octane fuel you can get. In the UK thats Tesco 99 Ron or Optimax 98 Ron. This is equiv to US 93 Ron. (they use the average of the Ron & Mon ratings which are 10 points apart). If the engine is pinking you definatly risk a holed piston at WOT !
If its pinking you can either:-
retard the timing,
or use higher octane fuel. The latter will give more power than the former.
The optimum timing point is 'as much advance as possible at WOT but without pinking'. Higher octane fuels burn slower therefore the time (crank degrees)spent pushing the piston down is longer,but you must commence the spark earlier to get the benefit . (more advance)
You can run either a good octane booster ,we use Aldon here in the UK at 'say' 40;1 mix or something like Sunoco Supreme which is very high lead & octane mixed 'say' 3;1 mix with Shell Optimax.
A hot engine is much more likely to pink/detonate than a cold one. IMHO poor fuel grade with too much advance is much more likely to hole a piston on a four stroke engine than a slightly lean mix.
Best Regards Roland GT Tuning

Re: Engine pinging when hot - OK when cool #95841
07/13/06 3:17 pm
07/13/06 3:17 pm
Joined: Jan 2005
Posts: 165
Canada
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jackd Offline
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Joined: Jan 2005
Posts: 165
Canada
I have a '71 T100C which I run on 94 Octane gas with B8ES plugs. This thing does ping if I start to load her and I let the revs start to drop - I just drop her down into a lower gear and all returns to normal. The noise that I am hearing is pre-ignition not detonation - two very different things. I never forget that I am only driving a 500cc machine and so I try to get my performance by keeping the revs in the useable range. I would never consider using a lower octane gas to save a few cents - penny wise but pound foolish. Jackd

Re: Engine pinging when hot - OK when cool #95842
07/13/06 3:45 pm
07/13/06 3:45 pm
Joined: Jul 2006
Posts: 12
Blandford, dorset ,UK
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rolandgttuning Offline
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Blandford, dorset ,UK
Yes pinking is actually the sound of the piston rattling in the bore due to too much advance for the fuel used. Pinking often leads to detonation,but by the time you realise it, its usually too late.
Regards Roland GT Tuning

Re: Engine pinging when hot - OK when cool #95843
07/13/06 4:05 pm
07/13/06 4:05 pm
Joined: Jun 2006
Posts: 316
Germany
KrispyKris Offline
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Germany
I never meant to infer that one should use a lower grade fuel to save money.

Rather my point was that if your engine is not designed for it, using a higher grade fuel is not only a waste of money, but hurts performance.

As a note though, I think the term is "pinging" not "Pinking," (unless this is a localized dialectic term). However, it is not the "pistons ratting in the bore" It is in fact, detonation of the fuel before TDC. Commonly refered to as pre-ignition. It occurs when the fuel/air mix is ignited either by high cylinder pressure, lean mixture, or by hot spots in the combustion chamber (glowing coke, or another hot spot, plug to hot, etc.)This creates abnormally high temparatures, and pressures in the chamber, and this is what puts the holes in the pistons...JK


BGL, Deutschland.
'67 Bonnie w/140V, '76 T160, '52 Vincent Rapide.
"Is that 'normal' mechanical noise, or the sound of imminent destruction...?"
Re: Engine pinging when hot - OK when cool #95844
07/14/06 8:47 am
07/14/06 8:47 am
Joined: Jul 2006
Posts: 12
Blandford, dorset ,UK
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rolandgttuning Offline
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Joined: Jul 2006
Posts: 12
Blandford, dorset ,UK
Hi, 'Pinking' is not a local dialect,it is the correct English terminology. 'Pinging' as you call it is an Americanism of 'pinking'. As this is a worldwide site the use of either is fine.
The sound you get with over advance IS coming from the piston rattling in the bore as the early spark is creating a shock wave that is trying to push the piston back down too early as its coming up on compression.
Pinking,pre-ignition & detonation are all different yet closely related as to the effect . Also one can easily lead to the other, and to the other (detonation!). Check out Dave Walkers Engine Management book for a detailed explanation of all 3. In essence for safety & power always use the highest octane you can readily get. Either that or back off the timing and lose a bit of power.
Best Regards Roland GT Tuning


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