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Pre ignition?
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Sute



Joined: 21 Jul 2013
Posts: 40
Location: Finland

PostPosted: Fri Jun 03, 2016 1:00 pm    Post subject: Pre ignition? Reply with quote

Okay guys,

I have got a four banger 2.0 litre Volvo aluminium engine. Running Garret GTX 4202R turbo and currently dynoed to 916 hp and 790 NM @ crank with 2,6 bar boost. Car / engine is used mainly for "fun driving" and standing mile events. Best so far from last season 329 kph. App 800 horses under the hood at that occasion. Running on E85 and CDI ignition (Autronic 500R and IGN1A CDI coils). ECU Vipec i88.

Was driving a week a go first standing mile and everything went well until putting 5th gear in before reaching 1000 m mark. Engine worked well for a 2-3 seconds but started to loose some power and finally made a slight hick up and lost some boost and at the same time saw a small smoke cloud behind me. Kinda pissed off seeing that smoke.. Evil or Very Mad

Here´s a youtube shot from the run:

https://www.youtube.com/watch?v=MdedYyIg950&feature=youtu.be

Took off the head and this was the result:

Cylinder #3



and cylinder #1



Took off the valves and that revealed that valve seats in #3 was badly melted.

Spark plug completely destroyed at cylinder #3 and tip melted at cylinder #1. New plugs on the run.




No melting signs on pistons. Some signs of spark plug remains on top of the piston at cylinder #3.

Some data from the run:

Lambda 0,73-0,74 on 4th and 5th gear. Lambda meter is Innovate LC1. Shows 0,02 richer than Motec lambda last time in dyno, very much same results as Autronic lambda meter):



EGT showing consistent and quite low values until app. 24 seconds from the start. Then cylinder 1 EGT began to cool and cylinder 3 to heat up a bit then finally skyrocketing when valves gave up completely:



Boost consistent during the run:



Knock control was dead calm during the whole run.

Any ideas whether this could be due to pre ignition caused by a spark plug possibly started to glow as plug being too hot? Running NGK 8 heat range copper plugs gabbed to 0,5 mm. From my opinion this should not be attributable of running lean although lambda meter of not being really state of art, but I´ve got consistent results compared to Motec and Autronic meters. However, no lambda figures measured from individual cylinders.

Ignition advance, running 1,5 degrees lower than in dyno where back up 1,5 degrees from MBT.

Would really be helpful for your pro ideas. Sorry for the bad English. Surprised
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baldur



Joined: 12 Oct 2007
Posts: 623
Location: Reykjavik, Iceland

PostPosted: Fri Jun 03, 2016 4:32 pm    Post subject: Reply with quote

Just shy of a thousand horsepower on a 4 cylinder that turns past 9k doing top speed runs and you're running ngk heat range 8? Definitely too hot. Might be borderline okay for 9 second quarter mile runs but top speed you definitely want something colder. I'd start with heat range 10 and short ground electrodes.
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Sute



Joined: 21 Jul 2013
Posts: 40
Location: Finland

PostPosted: Sat Jun 04, 2016 12:56 am    Post subject: Reply with quote

baldur wrote:
Just shy of a thousand horsepower on a 4 cylinder that turns past 9k doing top speed runs and you're running ngk heat range 8? Definitely too hot. Might be borderline okay for 9 second quarter mile runs but top speed you definitely want something colder. I'd start with heat range 10 and short ground electrodes.


Thanks Baldur!

So in your opinion pre ignition is possible cause here due to glowing plug? That I know, a common issue in alky engines, especially in methanol powered machines.

Many that I have talked with are saying engine´s been running lean momentarily and not seen in lambda sensor but in my opinion that´s not the case. The burning route seems to have started from the plug that I see.
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Pantera EFI



Joined: 12 Feb 2005
Posts: 1718
Location: So. California

PostPosted: Sat Jun 04, 2016 7:44 am    Post subject: Spark Plug Fire Band Reply with quote

First, look at the good plugs, state the Fire Band distance seen on the good plugs.
What is your spark plug gap used with the IGN-CD coil ?

My observation also states the Exhaust Valve got too hot.
What material is the exhaust valve ?

Your pistons are DESTROYED

Lance
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Sute



Joined: 21 Jul 2013
Posts: 40
Location: Finland

PostPosted: Sat Jun 04, 2016 8:07 am    Post subject: Re: Spark Plug Fire Band Reply with quote

Pantera EFI wrote:
First, look at the good plugs, state the Fire Band distance seen on the good plugs.
What is your spark plug gap used with the IGN-CD coil ?

My observation also states the Exhaust Valve got too hot.
What material is the exhaust valve ?

Your pistons are DESTROYED

Lance


Plug gab is 0,5mm with IGN-CD coil. Exhaust valves are Supertech Inconel valves.

Pistons do not look destroyed, gotta look at them again... Razz
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keithmac



Joined: 14 Nov 2010
Posts: 233

PostPosted: Sat Jun 04, 2016 11:00 am    Post subject: Reply with quote

Might be worth trying a set of colder strapless plugs?, you may struggle though if you have to run at 0.5mm gap.

I run NGK 8's on my 500hp GTO V6 (never does a top speed runs), so NGK range 10 was a good suggestion for yours.

You may end up swapping between 8's for daily driving duties and a colder set just for standing mile/ top speed events..
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MarcoV6T



Joined: 09 Jan 2007
Posts: 165
Location: Belgium, Brussels

PostPosted: Sat Jun 04, 2016 1:13 pm    Post subject: Reply with quote

Pre-ignition would rather melt a hole in the piston or head, this looks more like mechanical damage(broken not melted, due to tip of the plug).

So as others have mentioned, you'll need colder plugs for the long runs.

You did not mention the engine ECT, does(did) it go up a lot on the long runs? You could have had some minor knock which led to higher temps in the cylinder, which in turn burned the tips off.

I don't know how you need to tune the knock control on the Vipec, I've a Pectel SQ6(now branded Cosworth), but to make the knock control work flawlessly, you almost need an engineer to dial it properly in.
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joe90



Joined: 19 Mar 2013
Posts: 382
Location: under the car

PostPosted: Sat Jun 04, 2016 9:43 pm    Post subject: Reply with quote

More fuel required?
Needs to be richer.
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Sute



Joined: 21 Jul 2013
Posts: 40
Location: Finland

PostPosted: Sun Jun 05, 2016 12:41 am    Post subject: Reply with quote

MarcoV6T wrote:
Pre-ignition would rather melt a hole in the piston or head, this looks more like mechanical damage(broken not melted, due to tip of the plug).

So as others have mentioned, you'll need colder plugs for the long runs.

You did not mention the engine ECT, does(did) it go up a lot on the long runs? You could have had some minor knock which led to higher temps in the cylinder, which in turn burned the tips off.

I don't know how you need to tune the knock control on the Vipec, I've a Pectel SQ6(now branded Cosworth), but to make the knock control work flawlessly, you almost need an engineer to dial it properly in.


ECT was 83C and nothing wrong with this.

Colder plug seems to be consensus over here and this will be done.

Maybe it is test and try thing with this, but running lean is not going to my head as two cylinders had plug issues but no signs of running lean in lambda though - would there be some signs in data also? Adding more fuel as the engine is running 0.73 - 0.75 lambda seems quite odd to me. But I´m listening this option for sure.. Smile
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riceracing



Joined: 27 Apr 2013
Posts: 288

PostPosted: Sun Jun 05, 2016 2:08 am    Post subject: Reply with quote

You have other issues that caused the valves to burn, on those effected cylinders they were not seating correctly be that mechanical related clearance due to recession/angle contract or poor adjustment.

Its been thermally overloaded basically (due to leakage).
Aside from that the advice to run more excess fuel is well founded this will reduce the heat stress on the these parts and help with cooling, sans any major mechanical issue as mentioned above.

The spark plug heat range is way too hot for that displacement/power level on the given fuel type, 10 heat range for your application is far more normal. Get a good contact on your valve seats, adequate running clearance when hot to make sure they seat properly so they can conduct away the copious heat, and run 0.700 Lambda minimum. Its far less stressful on the engine to run some more MAP than it is to fuck around with less excess fuel chasing some abstract bullshit power gain advice handed out on forums by kids or older types who are mentally challenged Wink
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Wolf_Tm250



Joined: 26 Aug 2006
Posts: 475
Location: Parma - Italy

PostPosted: Tue Jun 07, 2016 2:00 am    Post subject: Re: Pre ignition? Reply with quote

Sute wrote:


Any ideas whether this could be due to pre ignition caused by a spark plug possibly started to glow as plug being too hot? Running NGK 8 heat range copper plugs gabbed to 0,5 mm.



While I don't know if there also is a mechanical problem with valves and seats,
I can tell you that I own a Renault 1.2 turbo gasoline 115 HP car where the OEM plugs are some NGK 7 heat range:
some 8 heat range in a 900 fwhp car are definitely way too hot, IMHO, and can happily lead to pre-ignition.
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Sute



Joined: 21 Jul 2013
Posts: 40
Location: Finland

PostPosted: Tue Jun 07, 2016 12:59 pm    Post subject: Re: Pre ignition? Reply with quote

Wolf_Tm250 wrote:
Sute wrote:


Any ideas whether this could be due to pre ignition caused by a spark plug possibly started to glow as plug being too hot? Running NGK 8 heat range copper plugs gabbed to 0,5 mm.



While I don't know if there also is a mechanical problem with valves and seats,
I can tell you that I own a Renault 1.2 turbo gasoline 115 HP car where the OEM plugs are some NGK 7 heat range:
some 8 heat range in a 900 fwhp car are definitely way too hot, IMHO, and can happily lead to pre-ignition.


That's pretty much what I am after - could a glowing plug lead to pre ignition or has there eventually been sudden lean conditions melting plugs and valves / seates.

Currently hunting for a new cylinder head and trying to hit new mile event on 18th June. Colder plugs for sure and maybe some more fuel.
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stevieturbo



Joined: 29 Aug 2006
Posts: 1235
Location: Norn Iron

PostPosted: Tue Jun 07, 2016 2:41 pm    Post subject: Reply with quote

As others have said, ensure valves are closed when they should be...and will always be. And a nice big fat seat for them to get rid of heat.
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got blown

9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0
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Sute



Joined: 21 Jul 2013
Posts: 40
Location: Finland

PostPosted: Sun Jun 26, 2016 11:05 pm    Post subject: Reply with quote

I showed this melted head to a head machining shop and according to them, this failure were due to the leakage in exhaust valves. Also survived exhaust valves had slight leakage. So first valves get hot and burn also plugs and aluminium in the head..?
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kamuto



Joined: 08 Dec 2013
Posts: 21

PostPosted: Tue Jun 28, 2016 5:36 pm    Post subject: Reply with quote

Sute wrote:
I showed this melted head to a head machining shop and according to them, this failure were due to the leakage in exhaust valves. Also survived exhaust valves had slight leakage. So first valves get hot and burn also plugs and aluminium in the head..?

exhaust stream going trough that not sealed gap worked like plasma cutter Smile
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Sute



Joined: 21 Jul 2013
Posts: 40
Location: Finland

PostPosted: Thu Nov 03, 2016 6:38 am    Post subject: Reply with quote

Okay, it seems that learning process is ongoing.

Got new cylinder head after the incident and headed to a new mile event at the end of August. Ran 2 runs with 309 kph and 320 kph respectively. Prior the event, engine was tuned with 4 channel Motec LTC to match the cylinder differences in terms of lambda. After the tune every cylinder showed quite close to 0.70 - 0.72 lambda. Peak power was 881 hp @ 2.5 bar of boost.

Again something happend during the second run. Two spark plugs failed / melted. Engine ran with new plugs after the event though. However had some head gasket leakage and decided to pull out the engine. Lambda during the run was consistent 0.70 - 0,72.

Beside the failed plugs (Brisk Turbo plugs, 8 heat range -> 10 at NGK scale), found out that the crown of piston #2 had practically collapsed, like forming a pit of a size of a thumb quite near to intake valve reliefs on a piston crown. No issues at the valves and cylinder head. Is this knock or pre ignition? If knock, could this really happen on intake side of a cylinder?



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stevieturbo



Joined: 29 Aug 2006
Posts: 1235
Location: Norn Iron

PostPosted: Thu Nov 03, 2016 9:07 am    Post subject: Reply with quote

I had a JE piston go like that...100% my own fault though.

Alternator had failed and I continued racing. Things were leaner than I'd like, probably too much timing....and also mile racing.

Seemingly that is not the case with yours unless there are issues with your Lambda meter.

In my engine most of the pistons ended up like that, it tuliped all the valves, blew a hole through the head/block interface when a gasket let go. Pretty impressive really lol And very bloody expensive.

It still drove afterwards though, I was very impressed by the JE pistons.

Your lambda seems to suggest otherwise, but the damage shouts lean/detonation.

Some oil jets under the pistons could be helpful too for cooling them down a bit for such use.

Any EGT data ?
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got blown

9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0
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Turboivo



Joined: 09 Mar 2006
Posts: 751
Location: Bulgaria

PostPosted: Thu Nov 03, 2016 12:43 pm    Post subject: Reply with quote

Was the spark timing advanced compared to the tune of the first engine damage?
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joe90



Joined: 19 Mar 2013
Posts: 382
Location: under the car

PostPosted: Thu Nov 03, 2016 6:42 pm    Post subject: Reply with quote

You probably STILL don't have enough fuel.
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baldur



Joined: 12 Oct 2007
Posts: 623
Location: Reykjavik, Iceland

PostPosted: Fri Nov 04, 2016 8:58 am    Post subject: Reply with quote

joe90 wrote:
You probably STILL don't have enough fuel.


I'm thinking since he's running four lambda sensors, are they corrected for pressure in a proper manner? With high pressure in the pipe, the sensor will read a lot richer than reality.
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