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onboost
Joined: 06 Mar 2009
Posts: 12
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 Posted: Fri Mar 06, 2009 5:30 pm Post subject: is this detonation, Pre- Ignition on Plug Help needed |
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ive got an sr20 (4cyl 2ltr) pushing 540hp @ wheels thru an automatic trans. GT35R turbo on 31psi on E85
This should be around the 600hp mark at the engine.
What i have noticed is i can't run much timing with E-85. We are down to around 5deg at peak trq. It still just speckles the plug which i cant seem to get rid off. As soon as i put more timing into it the engine sounds much nicer and make more power but the plug shows more speckles on porcelien. Keeping mixtures to around .75lambda and running ngk 9's
The thing is that the ground strap is anealing in the right spot, so im guessing cylinder temps arnt above normal and EGT's are reading around 1380 max (maybe due to lack of timing but still safe)
Now Im not sure if im at the end of the ocatane of the fuel, or is the specle on the plug just the rubbish fuel e-85 is mixed with.
Anyone seen this with E85?
I also used the briggs and stratton test kit on the fuel, although only marked to 30% (easy to mark the rest) read e90!
Ive maxed out 4 indy blue 842 injectors at 51psi fuel pressure and 2 bosch 044's.
Just wondering if the big boost guys are finding it hard to add timing?
Last edited by onboost on Fri Mar 06, 2009 11:07 pm; edited 1 time in total |
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393bird
Joined: 20 Dec 2007
Posts: 31
Location: Tennessee
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| Posted: Fri Mar 06, 2009 8:24 pm Post subject: |
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I am not having any issues at all. 15 psi of boost with 10.5 compression ratio,30 deg timing locked. Plugs look great.
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onboost
Joined: 06 Mar 2009
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| Posted: Fri Mar 06, 2009 8:47 pm Post subject: |
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im runnng 8.8cr.
I think it may be my intercooler, its only 600x300x76, it has only 2psi drop across the core but im not sure on the intercooler efficiency asyet. Im gonna have to weld a bung to monitor air temp in and out and see exaclty whats going on.
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TOYOTA COROLLA KE20 SR20DET 9.28@145 on E85 |
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onboost
Joined: 06 Mar 2009
Posts: 12
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| Posted: Fri Mar 06, 2009 9:35 pm Post subject: |
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My plug tiny specles.
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TOYOTA COROLLA KE20 SR20DET 9.28@145 on E85 |
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393bird
Joined: 20 Dec 2007
Posts: 31
Location: Tennessee
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| Posted: Fri Mar 06, 2009 9:43 pm Post subject: |
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With your very high boost level,you may have have to use water/meth injection above 20 psi,or find some E98.
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hotrod
Joined: 19 Apr 2005
Posts: 872
Location: Colorado
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| Posted: Fri Mar 06, 2009 10:18 pm Post subject: |
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Something is not right there, I know that properly tuned E85 will handle between 38-42 psi boost in the 4G63 engines, and slightly lower in the Subaru engine. You are up there but you still should not be getting detonation.
Is this a recent conversion or have you been running E85 for a while?
How old are those plugs?
By the way the title of your thread is wrong, you are not getting pre-ignition. If you were at 31 psi you would have melted pistons. You "might" be getting trace detonation but I doubt it. Pre-ignition is not the same as knock or detonation. It is a totally different process and due to hot spots in the combustion chamber, which are sometimes aggravated by detonation.
Back off the peak boost and find your best timing at about 24 psi, that should be about what timing the engine wants even at higher boost.
Do all your plugs look the same?
Frankly that plug does not look too bad to me. If anything you are still lean, but it looks to me like the temperature mark on the plugs is way down on the bend, it should be much closer to the end of the ground strap. It looks to me like it is about 2x as far down the plug as I would run it. The heat band on the electrode should be about 1/8 inch (2-3 mm) from the open end of the ground electrode, and you should have some temperature color in the top thread of the plug if you were hot or getting detonation.
At .75 lambda properly tuned you should have a little color on the plug.
Are those stock heat range plugs or one or two steps colder than stock?
At that boost level you should probably be running at least 1 step cold and perhaps 2 steps cold.
Not sure of how your engine timing marks are setup and how you are measuring timing.
If you are maxing out injectors there are two things you need to check. First what is the fuel pump actually moving under your conditions. You need to measure the supply voltage at the pump and compare that to what it should be getting. Many fuel pumps drastically lose fuel flow capacity even though they can manage the pressure if voltage drops under boost.
I would suggest you set up a test rig and actually measure the fuel pump out put at full system pressure and find out what its maximum fuel flow volume capacity is at that supply voltage and at full system fuel pressure.
Second what is your injector duty cycles? If you are maxing out the injectors and they are showing duty cycles over 90% you are risking melting an engine due to lean out. Many injectors will latch up and fail to open properly under full load, especially if fuel pressure is high, and or system voltage is low. You might want to send the injectors out to witch hunter or RC engineering to have the flow checked and cleaned. You might have injectors that are getting erratic at high boost and leaning you out. If you static fuel pressure is 51 psi at peak boost of 31 psi your system fuel pressure is 82 psi which is over the recommended max pressure of about 73-75 psi where many injectors start acting funky.
Do you have a knock sensor on your engine that pulls timing when it hears detonation, or are you running with no dynamic timing control?
Do you have det cans to listen for detonation?
Where do you live (region)? Are you tuning on a dyno or doing road tunes on your own?
For practical purposes you cannot run a plug that is too cold. The worst thing that will happen with a too cold plug is the car will be hard to start.
Under some circumstances low EGT's can indicate detonation.
Have you done a compression test or a leak down test to verify you have healthy cylinders, if oil is getting in the cylinder under high load, that can also trigger detonation.
Larry |
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onboost
Joined: 06 Mar 2009
Posts: 12
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| Posted: Fri Mar 06, 2009 10:56 pm Post subject: |
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thanks for the reply, this is a recent conversion and im pretty sure that this is the fasted e85 power car in Australia at the moment.
Well the reason i thought it was pre-ignition was because if it did detonate it would be too late. Also bad intercooler will cause pre-igniton because of the overheated air intake temp. never the less i was just trying to suss out whats up with my plug.
As far as lower boost goes we are able to run more timing no probs and keep the plug clean, its only since we are stepping up to the over 30psi range we are getting this.
I have also gone to a larger turbocharger with alot larger turbine housing to see if it were a back pressure issue and had no luck.
As far as the plugs got they are 3 steps calder than stock.
Any richer and the engine really starts to struggle to make power and begins to missfire even at 18thou gap with msd dis4 HO ignition.
Ive done flow tests at 51psi and 83 psi of fuel pressure.
11.2ltrs per min @51psi
8.8ltrs per min @83psi
injectors at max duty at 43 psi will only flow 7.6 ltrs per min, and lets say 8.5 at the higher base pressure.
I know im on the border line of fuel flow and will be adding another pump to fight g-forces etc, but i am within the limit at this stage.
Regardless the mixture is there thru the whole run at the track, the EGT's are within 40deg of eachother the back being the coolest due to my inlet manifold design (not much space)
Timing is the actualy number ive stated its a standalone ecu, ive adjusted my pointer to give me tru tdc aswell.
As far as using knock boxes ive tried them and can hear squat, we can usually here this engine knocking when it does knock hard. although we had earmuffs on, heads in the engine bay and people down the end of the shop and no1 could hear it. I dont trust knock boxes ive seen them destroy engines, i believe the plug shows before it will knock.
Are specles before detonation? or detonation? my experience with destroying engines is u usually see descent size specles before u start actually melting a plug wich then leads to melt down.
These are only tiny Black speckcles, could they just be carbon deposits getting flown around the cylinder? the reason why i say this is because the engine really loves the timing on the dyon but the plug doesnt.
My engine has large ring end gaps and my leakdown umbers are around 20-15%. always have been.
This is why im starting to think about my intercooler, although i was using nitrous on the dyno the other day and even that was specking the plug, even though nitrous acts like an interooler itself.
I really cant get my head around tghe speckles lol.
Im located in melbourne Australia, and have plenty of dyno access.
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Drag Chevette
Joined: 18 Sep 2007
Posts: 458
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| Posted: Fri Mar 06, 2009 11:34 pm Post subject: |
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if carb cleaner and a rag takes it off its carbon from the cylinder....
if it is burnt into the plug, its detonation and a colder plug or more fuel is required.....
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onboost
Joined: 06 Mar 2009
Posts: 12
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| Posted: Fri Mar 06, 2009 11:43 pm Post subject: |
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thats an idea im gonna give it ago
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onboost
Joined: 06 Mar 2009
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| Posted: Fri Mar 06, 2009 11:49 pm Post subject: |
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i didnt have any carbi clean, but i had brake clean, took 50% off but the rest looks like its ben pretty baked on there
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hotrod
Joined: 19 Apr 2005
Posts: 872
Location: Colorado
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| Posted: Fri Mar 06, 2009 11:51 pm Post subject: |
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Hmmmm --
3 steps colder should be good enough.
15%-20% leak down bothers me, you might want to check your crank case pressure under boost. With that much leakdown and boost you should be putting a lot of mixture into the crankcase. I hope you have good breathers.
That much leak down might be putting oil in the cylinder which gets spooky fast.
The rule of thumb is detonation breaks things, (broken piston ring lands, pounds out bearings etc.)
At high load, high rpm detonation is hard to hear sometime. Sometimes it is easier for a spectator at the top end to hear the engine than the driver, you might try having some one video tape you near traps to see what the engine sounds like under high load and full temp.
By the way a too narrow spark gap can also cause detonation by resulting in too much ignition delay in the early stages of the burn. Larger gaps burn faster than narrow gaps for the first few milliseconds of ignition.
I noticed you are using conventional plugs you might also try running a J-gap plug, my engine really likes them. I run Champion C59YC racing plugs which are an over the counter J-gap racing plug.
Pre-ignition melts stuff -- big holes in pistons like you put a blow torch on them. Fatal pre-ignition is silent but very quickly fatal --- the engine is dead before the driver can lift throttle under high load.
Sometimes detonation does lead to pre-ignition due to the detonation blowing the insulation dead air layer off the top of the piston allowing it to heat very quickly. This is also why EGT's sometimes drop suddenly under detonation as heat that should be going out the exhaust pipe is going into the head, valves and piston crown.
I agree you need to get before-after temps on the intercooler to see if it is getting the job done on high boost. You might also want to take a look at your exhaust gas back pressure between the head and the turbo. On a big turbo with a large hot side full race setup, it should get down near the same as boost pressure if everything is sized right. Stock turbo setups have too small hot sides and can run exhaust back pressures as high as 2.5x boost pressure.
| Quote: | | Are specles before detonation? or detonation? my experience with destroying engines is u usually see descent size specles before u start actually melting a plug wich then leads to melt down. |
On my engine I never see black speckles only the silver balls. My engine (Subaru WRX) is an aluminum head which might explain that. I understand their are two theories on the dark speckles one is that is is iron from iron heads others say it is carbon flakes melted onto the plug.
In my engine, you will see very light gray haze of aluminum on the plug first. Without a 10x magnifier you won't even notice it. If you look closely it is microscopic spray of molten aluminum sprayed all over the plug. If you index the plug you can see what direction it is coming from as it will be heavier on one side of the plug. In my engine it detonates near the rear intake valve first (exhaust side burns faster).
As detonation gets worse, it changes from a faint haze to distinct bright shinny balls of aluminum that look like microscopic ball bearings. The tend to cling to the ground electrode first in my engine. If you look very closely at the center electrode instead of being smooth and rounded like you would expect the corners begin to look like they were sandblasted or chewed on by a very very small rodent. Then I understand you start to see bubbling of the porcelain near the center electrode and then cracks and broken plugs. If you pull the heads you can see the same sand blasted look on the top of the pistons in the area near where it is detonating.
You might want to cut your plugs apart and look at the mixture ring at the base of the center porcelain. You take a hacksaw and cut the threaded portion of the plug off just below the wrench flats so the center electrode insulator is exposed. At the very base of that insulator a faint discoloration ring forms that shows the mixture under heavy load. It supposedly is harder to see on alcohol fuels but still there.
The mixture ring can only tell you what is going on when everything else is just about perfect though, but here is what I've been told.
On a Drag car you need to put 3-4 good passes on the plugs before they will show color. You may need to clean the porcelain with a spray carb cleaner. When everything is right, on gasoline you will have clean white porcelain with a dark ring about 1/16 inch (1.6mm) wide that circles the porcelain as close as possible to where the plug body grips the insulator.
When every thing is right all plugs will have equal width rings of equal darkness (balanced mixture). If you have one or more plugs that are significantly different than the average of the others it is telling you its burn conditions are different. Rich makes for wider darker rings, lean leads to thin weak rings.
On E85 the fuel coloration is much weaker but it is still there from my experience, so you should still see some color down there. I have never done this on my E85 setup so cannot say from experience how much weaker but I know even methanol leaves a weak mixture ring.
You need at least a 10 x magnifier to really see the signs of detonation, you can't see enough detail with out one. You also need very good light (sun light) or an illuminated magnifier.
On high power turbocharged boat engines my friend likes to see a fuel mixture ring almost 1/8 inch (3 mm) wide to keep them from melting (1000hp engines).
By the way where are you measuring your mixture in the exhaust system.
Sorry I can't give you a clear culprit to look for, but I suspect as you mentioned that you are perhaps running out of fuel under peak load (problem will show up at max torque) or the intercooler is not getting the job done. At the sort of boost you are running you might want to play with water injection on top of the E85 too, but that would add a new variable to deal with.
Larry |
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onboost
Joined: 06 Mar 2009
Posts: 12
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| Posted: Sat Mar 07, 2009 6:40 pm Post subject: |
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well me esperience so far with ethanol is it does not have a fuel ring, i did see something once but it was not a black ring i think it was blue or green ring i cant remember now. The stuff burns so clean.
Ok now does urs look like aluminium or do they look black and when u look at it with the magnifying glas they turn grey?
Ive never seen these grey balls or anything like that on my plugs.
Ive bever seen gray, ive orded a magn. to have a closer inspection.
I have one -12 and one -10 brethers, its got pletney to breath from.
here is a datalog of one of my passes, rpm vs egt vs A/F (gas calibrated)
converting those egt's from C to F., am at the 1410 mark toward the end of the pass.
I measuring about 1.5 from the back of the turbo, half way down the dump pipe.
How well does water alcohol injection work with e85? do u think it will help me in my case?
Thnx for the reply's ill take all this on board and hopefuly fix my problem.
i got a couple vis on my car at these links
http://www.fullboost.com.au/video.php?startRow=10&endRow=20&page=2
Calder Park LOSD part 1/2 January 21st, 2009 u see the white corolla thumbnail thats mine, may car is about 3/4 way thru the vid
this is the other one link titled Calder Park - 4, 6 & Rotary
March 4th, 2009 im the third car in the vid.
http://www.fullboost.com.au/video.php?startRow=0&endRow=10&page=1
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hotrod
Joined: 19 Apr 2005
Posts: 872
Location: Colorado
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| Posted: Sun Mar 08, 2009 1:06 pm Post subject: |
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| Quote: | | How well does water alcohol injection work with e85? do u think it will help me in my case? |
It should work well, given its history of use on high performance aircraft engines, even on 120 octane av gas they got better results with water/alcohol injection.
I plan to play with it someday but have all those plans on hold now until I find a job.
I'm not familiar with that sort of log output, and may be misinterpreting it (I am red green colorblind) but looks like the trace that zig zags all over the map is the AFR trace, if so as I read it looks like your going super lean around 4000-5000 rpm ?? If there is a boost trace on the map I cannot see it.
Larry |
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Eric68
Joined: 01 Nov 2007
Posts: 331
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| Posted: Sun Mar 08, 2009 8:45 pm Post subject: |
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| hotrod wrote: | it looks to me like the temperature mark on the plugs is way down on the bend, it should be much closer to the end of the ground strap. It looks to me like it is about 2x as far down the plug as I would run it. The heat band on the electrode should be about 1/8 inch (2-3 mm) from the open end of the ground electrode, and you should have some temperature color in the top thread of the plug if you were hot or getting detonation.
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That was exactly the same as my observation. Either too much timing or the plug is too hot (or both).
I think you have too much heat in the plug -- I would fix that first.
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crispeed
Joined: 24 Dec 2007
Posts: 98
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| Posted: Mon Mar 09, 2009 12:52 pm Post subject: |
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What is your air intake temps from the begining to the end of the run? Also where do you measure the AIT at?
Are all the ground electrodes looking the same?
What rpm is peak torque?
You got a log of the ignition timing?
Care to share the ignition map?
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