Topic: Detonation Damage on 20v Pistons

This is how much detonation can damage pistons.

This is one of my old 20v pistons with a broken ring gland caused by detonation. So....guys...please keep your car out of detonation/pinking.

All std 20v's keep your ignition timing at 16 degrees max....preferably just under that to be safe.

Notice the carbon build up on the piston caused by a blocked injector. The carbon caused an increase in compression in the chamber and thus detonation.

http://img.photobucket.com/albums/v187/twincamsam/DSC01290.jpg
http://img.photobucket.com/albums/v187/twincamsam/DSC01298.jpg

Corolla RXi 20v Blacktop                    87 RSi 4AGE 16v "DBN Stock"- 282Wkw @ 1.8 bar
TRD 0.8mm Head Gasket                   Turbonetics 0.63 A/R T3/T4 turbocharger
Yoshimura 270 cams                         Turbonetics Evolution Wastegate
TODA valve Springs                          Built ZE 8.9 bottom end, ARP, FMIC
63mm Exhaust                                 Boost Cooler, Full Management

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Re: Detonation Damage on 20v Pistons

fark me! my car is pinging at low revs now........ fark, i needta sort it out asap huh.

thnx sam

1998 Toyota Corolla RSi
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Re: Detonation Damage on 20v Pistons

Yoh !!! dats bad

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Re: Detonation Damage on 20v Pistons

UM guys, supid question: WHAT IS DETONATION???:/

Current: '00 Rxi BlackTop http://i285.photobucket.com/albums/ll70/KAMZ20v/burnrubber.gif

http://i285.photobucket.com/albums/ll70/KAMZ20v/69d97f9e-a3eb-4840-87cc-0e10cb2754d7.jpg

Re: Detonation Damage on 20v Pistons

http://en.wikipedia.org/wiki/Engine_knocking

http://i486.photobucket.com/albums/rr227/AndreK_bucket/RXi/image002-1.jpg

20V Corolla ../../extensions/custom_smilies_2/img1/devil

Re: Detonation Damage on 20v Pistons

Here's what's going on in the cylinders inside the engine during pinging or knocking:

http://i280.photobucket.com/albums/kk184/RXi_20v/ping1.gif

Illustration #1 The piston begins to move upwards during what's called the, "compression stroke," compressing a mixture of fuel and air.

http://i280.photobucket.com/albums/kk184/RXi_20v/ping2.gif

Illustration #2 In a normally operating engine, the spark from the spark plug ignites the mixture of fuel and air, causing an extremely rapid burning of the fuel in the cylinder. That's good. It's what creates the pressure that makes the piston travel down very fast, causing the crankshaft, your transmission, and ultimately the wheels — to turn.

http://i280.photobucket.com/albums/kk184/RXi_20v/ping3a.gif

Illustration #3 However, it's possible for the mixture of gas and air to burn somewhere else in the cylinder, simply from the pressure (or compression) within the cylinder, and not from the spark. That's called "pre-ignition," and it's more likely in a high-compression engine. Illustration #3 However, it's possible for the mixture of gas and air to burn somewhere else in the cylinder, simply from the pressure (or compression) within the cylinder, and not from the spark. That's called "pre-ignition," and it's more likely in a high-compression engine.

http://i280.photobucket.com/albums/kk184/RXi_20v/ping4.gif

Illustration #4 When the fire you want (that's the one from the spark plug), collides with the fire you don't want (that's the one resulting from the pre-ignition), the result is a ping or, if the pre-ignition fire is big enough, a knock. The degree of severity, including the amount of noise generated, is determined by how big that unwanted flame is.

http://i280.photobucket.com/albums/kk184/RXi_20v/96180RSi_small.jpg http://i280.photobucket.com/albums/kk184/RXi_20v/20V_small.jpg
http://i280.photobucket.com/albums/kk184/RXi_20v/XRSi_small.jpg
http://i280.photobucket.com/albums/kk184/RXi_20v/Xluv_small.jpg

Re: Detonation Damage on 20v Pistons

@ DonnieB very nice illustration ../../extensions/custom_smilies_2/img1/cool

╭∩╮(︶︿︶)╭∩╮
  02' RXi 20v
  92' GLi Exec [ex]

Re: Detonation Damage on 20v Pistons

Car Knock Sensor

Vehicle Knock SensorThe Knock Sensor detects engine knock and sends a voltage signal to the ECM. The ECM uses the Knock Sensor signal to control timing. Engine knock occurs within a specific frequency range. The knock sensor, located in the engine block, cylinder head, or intake manifold is tuned to detect that frequency.
The knock sensor senses when fuel is burning unevenly and causing “knocking” or irregular vibrations in the engine. It consists of an electric coil that is wound around two ceramic rods with a magnet in the center. The vibration of the engine causes the rods to vibrate. This disturbs the coil’s magnetic field and alters the current passing through the coil. This disturbance returns to the computer as a signal pattern that the computer analyzes. The computer then determines whether the vibrations are characteristic of engine knocking.

http://i280.photobucket.com/albums/kk184/RXi_20v/96180RSi_small.jpg http://i280.photobucket.com/albums/kk184/RXi_20v/20V_small.jpg
http://i280.photobucket.com/albums/kk184/RXi_20v/XRSi_small.jpg
http://i280.photobucket.com/albums/kk184/RXi_20v/Xluv_small.jpg

Re: Detonation Damage on 20v Pistons

Fantastic explanation & illustration Donnie, thanks now I SEE IT!!! SHOT:D

Current: '00 Rxi BlackTop http://i285.photobucket.com/albums/ll70/KAMZ20v/burnrubber.gif

http://i285.photobucket.com/albums/ll70/KAMZ20v/69d97f9e-a3eb-4840-87cc-0e10cb2754d7.jpg

Re: Detonation Damage on 20v Pistons

Sam , i got 18deg timing at the moment running up here in JHB and no pinging etc at all , and my car makes power at that timing , but bear in mine , im also running a vernier pulley and my exhaust timing is now retarded????

is there any risk of me messing up anything , car was tuned on a dyno

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Re: Detonation Damage on 20v Pistons

I have personally known of 20v's running up to 20 deg timing in dbn.

The key is to make sure that the car stays out of detonation....

18 does seem a bit high for altitude though?  mmm just make sure u filling up with 95 all the time.   ../../extensions/custom_smilies_2/img1/wink

Corolla RXi 20v Blacktop                    87 RSi 4AGE 16v "DBN Stock"- 282Wkw @ 1.8 bar
TRD 0.8mm Head Gasket                   Turbonetics 0.63 A/R T3/T4 turbocharger
Yoshimura 270 cams                         Turbonetics Evolution Wastegate
TODA valve Springs                          Built ZE 8.9 bottom end, ARP, FMIC
63mm Exhaust                                 Boost Cooler, Full Management

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Re: Detonation Damage on 20v Pistons

TwincamSam wrote:

I have personally known of 20v's running up to 20 deg timing in dbn.

The key is to make sure that the car stays out of detonation....

18 does seem a bit high for altitude though?  mmm just make sure u filling up with 95 all the time.   ../../extensions/custom_smilies_2/img1/wink

ok kewl thanks , i only use 95vpower, but it still concerns me on why is my car running so high timing as compared to others up here , we run more or less that same KW ratings etc.

on the road , however , my 20 seems to start to pull away for some odd reason and i was told that the 57mm piping is holding me back alot , so im changing tomorrow to 63mm , hopefully no probs ....will keep this updated as well , maybe after the 63mm install , the pinging may start.

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Last edited by shaun (2008-09-19 15:46:37)

Re: Detonation Damage on 20v Pistons

Naa i doubt it.....u really lucky i guess. Just monitor for detonation  and u will be fine.....any slight ping and pull the timing back.  ../../extensions/custom_smilies_2/img1/wink

Yeh 63mm FTW!!

Do u have a stock branch Shaun?

Just remember to reset the ECU after any change

Corolla RXi 20v Blacktop                    87 RSi 4AGE 16v "DBN Stock"- 282Wkw @ 1.8 bar
TRD 0.8mm Head Gasket                   Turbonetics 0.63 A/R T3/T4 turbocharger
Yoshimura 270 cams                         Turbonetics Evolution Wastegate
TODA valve Springs                          Built ZE 8.9 bottom end, ARP, FMIC
63mm Exhaust                                 Boost Cooler, Full Management

PM me for all 9000RPM Stickers, T-shirts,Caps
Legends Never Die....They are just Reborn with BooSt
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Re: Detonation Damage on 20v Pistons

ok heres my feedback after this weekends playing around

took off the 57mm wildcat and stock branch and got Viper to build me a custom 63mm 2 box exhaust system with a custom branch , will explain in another post of exactly what i did and where i got my info etc for the branch build to eliminate that famous flat spot.

anycase , fitted the branch and exhaust , left the timing the same @18deg and retarded exhaust timing with the use of a vernier pulley , but did a ECU reset , must say no pinging at all still , not even the slightest ,car is pulling very strong , much stronger than before , no flatspots nothing , trust me im a happy chappie.

will start a thread here as well on this forum with pics and explanations of what i have done and doing , including step by step , with dyno reads of the toda cams install etc.


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Last edited by shaun (2008-09-22 09:00:04)

Re: Detonation Damage on 20v Pistons

Great stuff Shaun.

Just be weary when adjusting your cam timing because this throws your ignition timing off.

First set your ex vernier. Then set the ignition timing with a timing light.

../../extensions/custom_smilies_2/img1/wink

Put up a full thread documenting your progress.

Corolla RXi 20v Blacktop                    87 RSi 4AGE 16v "DBN Stock"- 282Wkw @ 1.8 bar
TRD 0.8mm Head Gasket                   Turbonetics 0.63 A/R T3/T4 turbocharger
Yoshimura 270 cams                         Turbonetics Evolution Wastegate
TODA valve Springs                          Built ZE 8.9 bottom end, ARP, FMIC
63mm Exhaust                                 Boost Cooler, Full Management

PM me for all 9000RPM Stickers, T-shirts,Caps
Legends Never Die....They are just Reborn with BooSt
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Re: Detonation Damage on 20v Pistons

thanks SAM , will do so

and yeah i always do vernier then engine timing

../../extensions/custom_smilies_2/img1/wink

Re: Detonation Damage on 20v Pistons

Going up hill in my 92 with silver top 20v I can hear some pre-ignition from time to time if its warm. 32degrees +.
I run 250ml of octane boost with 98 fuel all the time, and it seems to do away with it.
Standard cams, BT ecu with stacks, retarded exhaust cam timing and 10degrees static timing. It goes pretty well, but think I can retard the exhaust a little more.
Think I have only retarded it by 1or 1.5degrees.

Sam, were you running 95octane when you had the detonation?

Re: Detonation Damage on 20v Pistons

Yip plain jane 95 octane.

U shouldnt have any problem at all on 10 deg advance with 98 octane ?

Corolla RXi 20v Blacktop                    87 RSi 4AGE 16v "DBN Stock"- 282Wkw @ 1.8 bar
TRD 0.8mm Head Gasket                   Turbonetics 0.63 A/R T3/T4 turbocharger
Yoshimura 270 cams                         Turbonetics Evolution Wastegate
TODA valve Springs                          Built ZE 8.9 bottom end, ARP, FMIC
63mm Exhaust                                 Boost Cooler, Full Management

PM me for all 9000RPM Stickers, T-shirts,Caps
Legends Never Die....They are just Reborn with BooSt
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Re: Detonation Damage on 20v Pistons

Is your knock sensor wired in a working correctly. may be asking the obvious, none the less, are you running a map sensor in addition to the tps signal? Silvertop ran airflow meter for 90% of the load metering. Blacktop ran map sensor for 90% of load metering. Your mods shouldn't bring on pinking or detonation. Are you running stock headgasket and have you skimmed your head to up compression ratio? Lastly, is your exhaust system by chance restrictive, maybe anything less than 57mm diameter?

Re: Detonation Damage on 20v Pistons

Apparently its quite common over here in Australia.
Stock head gasket, complete blacktop wiring conversion with blacktop ecu, map, and a brand new TPS.
exhaust is 2.5inch, which is above the recommendation.
No head modification or skimming.
Have not removed the head since installing in my car.
Do not believe the block had been decked by previous owner in Japan either.

I am a little suprised you guys are running 85 without any issues, especially with aftermarket cams, and some on stock ecus.
I will be changing ecu in the future to MoTeC standalone, should solve the issues, if the timing map is correct...