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kpturbo
Joined: 27 Jan 2010
Posts: 4
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 Posted: Mon Feb 08, 2010 8:19 pm Post subject: What has happend to my plug?? |
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Hello.
Is there someone who can help me find out what has happend to this plug?
As you can see a bit of the porcelen has come of also and hit my valve and valveseat on the way out  ..
Is a platinum heatrange 8 Ngk plug.
The engine is a 650hp nissan SR20DET running only 1.65bar og boost with E85.
I suspect I have been running lean and have had some detonation.
The plug is from sylinder 1 and here are a picture of the plug on sylinder 2
The plugs in sylinder 3 and 4 looks the same as number 2.
Thanks for all the help you guys can give me.. |
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murphinator
Joined: 08 Jan 2010
Posts: 57
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| Posted: Mon Feb 08, 2010 10:01 pm Post subject: |
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chunked a piston and smashed an electrode ? or leaned out enough to melt off an electrode ?
wideband tuned ? wot afr ?
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PB's 1/4 mi 12.209, 117.75 trap ,1/8 mi 7.76 ,93.99 trap , 1.949 short time 4.53 0-60
I tune with HP Tuners software |
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kpturbo
Joined: 27 Jan 2010
Posts: 4
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| Posted: Tue Feb 09, 2010 4:56 am Post subject: |
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| murphinator wrote: | chunked a piston and smashed an electrode ? or leaned out enough to melt off an electrode ?
wideband tuned ? wot afr ? |
Theres no damage on the piston so I dont think anything has hit the plug. I also think I maybe leaned out on sylinder 1 but sadly I didnt have EGT sensors on each sylinder at the time. The engine is wideband tuned but I dont remember the AFR..
Im running bosch 1600cc injectors and two walbro 255pump with AN8 fuellines so I know that im getting enough fuel. But maybe one of the injectors did not perform as it should. I just wanted to know if maybe my timing was the problem.. |
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nelson8708
Joined: 22 Aug 2008
Posts: 63
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| Posted: Tue Feb 09, 2010 7:27 pm Post subject: |
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it was probably a injector problem, not performing like you said. Typically the #1 cylinder is the richest running and #4 is the leanest because of the intake manifold layout.
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KA-T for 2 1/2 years now |
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89shortbox
Joined: 04 Nov 2007
Posts: 135
Location: Michigan
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| Posted: Thu Feb 11, 2010 12:59 am Post subject: |
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the cut plug fuel ring looks like it should have been a good tune
How much timing under full boost and AFR.
_________________
----------------------
89 S10
406 SBC Twin Turbo BT
Going E85 this coming season
HAHA, the season is alreay gone to another season. |
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kpturbo
Joined: 27 Jan 2010
Posts: 4
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| Posted: Fri Feb 12, 2010 10:13 am Post subject: |
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| 89shortbox wrote: | the cut plug fuel ring looks like it should have been a good tune
How much timing under full boost and AFR. |
Sorry but I dont remember the timing and AFR. I buildt the engine but i dont tune it myself. That I leave to the experts  ..
But I have another question for you guyes. Is it normal that it is much more breathing from the crankcase on E85?? I could see alot more "steam" coming from my catchtank with E85 then it was with 98ron petrol..
I have talked with some friends that use E85 on rallycars and they say that its normal especially if you have alot of HP... |
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Eric68
Joined: 01 Nov 2007
Posts: 308
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| Posted: Sat Feb 13, 2010 7:44 pm Post subject: |
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The melted plug is from detonation and probably a little pre-ignition that followed. The smoke from the breather is a sign that there is more wrong with the piston that what you have seen so far. I bet you hurt a ring land and have not realized it yet. Better have a good look at them pistons or do a good leak down check.
What I have learned with E85 is that it seems that the early signs of detonation are not as evident as they are with gasoline. The specs on the porcelain don't seem to show up -- the piston just melts down. That is not to say that E85 is any more dangerous than gas, it just doesn't have as much carborn content as gasoline and as a result the black carbon specs that you see on the electrodes don't show up when using E85.
_________________
E85 racer and E85 carb builder
www.horsepowerinnovations.com
E85 powered 68 Camaro street car
Best ET on motor 10.04 @ 132 MPH, 5.95 on N2O in the 1/8th |
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hotrod
Joined: 19 Apr 2005
Posts: 812
Location: Colorado
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| Posted: Sun Feb 14, 2010 4:18 pm Post subject: |
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I would concur, get a leak down test and compression test to verify that cylinder is healthy. A bit of oil leakage past a wounded piston/ring can drastically lower the effective octane of the fuel in that cylinder.
Turbocharged cars are notorious for seeming to run fine (although just a tad flat) on an engine with one wounded cylinder. The boost hides the weak cylinder until it gets bad. If you have the means to monitor crank case pressure, or blow by volume (some dyno operators can do this) that could also show health of the ring seal.
When one cylinder has such a problem and others appear normal the first two things I would check is health of the piston/ring package and the injectors.
Larry |
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kpturbo
Joined: 27 Jan 2010
Posts: 4
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| Posted: Fri Feb 19, 2010 2:22 pm Post subject: |
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| hotrod wrote: | I would concur, get a leak down test and compression test to verify that cylinder is healthy. A bit of oil leakage past a wounded piston/ring can drastically lower the effective octane of the fuel in that cylinder.
Turbocharged cars are notorious for seeming to run fine (although just a tad flat) on an engine with one wounded cylinder. The boost hides the weak cylinder until it gets bad. If you have the means to monitor crank case pressure, or blow by volume (some dyno operators can do this) that could also show health of the ring seal.
When one cylinder has such a problem and others appear normal the first two things I would check is health of the piston/ring package and the injectors.
Larry |
Well since the engine is already taken apart it would be a little difficult to measure the anything at this time ..
There maybe was some damage to the pistonrings because the engine startet fill up my catchtank with oil so maybe your are right about oil in sylinders and that caused the engine to knock.. But in which order everything happend is still a mystery to me. Was it the oil in the sylinder that made the engine to knock first and then the plug melted, was it a bad injector that made the sylinder go lean and then the pistonring gave up and startet to leak oil in the sylinder or maybe there was something else, I dont know..
Since I dont have any info on AF/R, EGT, Crankcase pressure etc everything is just speculation. But since im now building a new engine I will do some new mods to prevent this happening again.
First of is this:
A Phormula knock analyzer so I can hear the engine at all times. I have used this in the past and it works great. I dont know if I can get the time to cut the the throttle if hear it knocking but its better then nothing. I also have a Stilo WRC helmet with buildt-in intercom so I can also plug in the Phormula when im on the track..
I will also modify my crankcase breathing system also with a bigger and better Catchtank design.
And im going have EGT sensor on each sylinder this time ..
Here is my pocketrocket if someone wants to see it. Its a 79mod rwd toyota starlet 
Yes its a mean bastard  |
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murphinator
Joined: 08 Jan 2010
Posts: 57
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| Posted: Fri Feb 19, 2010 8:23 pm Post subject: |
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that knock analyzer looks a bit more high tech than these , very nice 
and that car looks sick - I am a GM guy but always appreciate anything that performs and from the hardware I see it has to be a beast.
What have you been doing with it and what type of results ? power to weight has to be off the charts.
dont take offense but kind of shaped like a cross between a chevette and a vw rabbit
_________________
PB's 1/4 mi 12.209, 117.75 trap ,1/8 mi 7.76 ,93.99 trap , 1.949 short time 4.53 0-60
I tune with HP Tuners software |
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Eric68
Joined: 01 Nov 2007
Posts: 308
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| Posted: Fri Feb 19, 2010 10:15 pm Post subject: |
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That's a neat lookin little car. I'm not an import fan, but for some reason I LIKE yours. Keep it up 
_________________
E85 racer and E85 carb builder
www.horsepowerinnovations.com
E85 powered 68 Camaro street car
Best ET on motor 10.04 @ 132 MPH, 5.95 on N2O in the 1/8th |
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peter
Joined: 06 Mar 2009
Posts: 11
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| Posted: Thu Mar 04, 2010 11:42 am Post subject: |
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Have any of you guys actually heard knock when using E85? I've been told that with E85 the engine will explode before there's any detonation that can be heard. I'm still wondering if it starts to raise the cylinder pressure as the timing is increased before actual detonation and therefore blow up the motor before knocking can be heard?
As mentioned with gasoline detonation can be monitored fairly easily with basic headphones or with a knock analyzer. Maybe these are useless with E85 tough.. ?
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hotrod
Joined: 19 Apr 2005
Posts: 812
Location: Colorado
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| Posted: Thu Mar 04, 2010 12:00 pm Post subject: |
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I only know of one person that has actually logged knock on an E85 engine.
It was a DSM (Mitsubishi) 4G63 engine and he was running 35 psi of boost on E85 and a bit too lean during shift throttle lift, and then back on the throttle (EFI).
In other words -- if your mixtures are in safe rich territory, it is almost unheard of. Pre-ignition on lean mixtures is far more likely than knock (although they sometimes trigger each other).
Larry |
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peter
Joined: 06 Mar 2009
Posts: 11
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| Posted: Thu Mar 04, 2010 12:31 pm Post subject: |
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| hotrod wrote: | I only know of one person that has actually logged knock on an E85 engine.
It was a DSM (Mitsubishi) 4G63 engine and he was running 35 psi of boost on E85 and a bit too lean during shift throttle lift, and then back on the throttle (EFI).
In other words -- if your mixtures are in safe rich territory, it is almost unheard of. Pre-ignition on lean mixtures is far more likely than knock (although they sometimes trigger each other).
Larry |
So basically when timing is added it is most likely that the power actually starts to drop before there's detonation/knock? I'm going 3.4l stroker on my supra and upping the compression ratio from 8.5:1 to 9:1. You think I would still be able to run as much timing/boost as before with E85? Probably 30-35psi is the max boost I'd use.
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hotrod
Joined: 19 Apr 2005
Posts: 812
Location: Colorado
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| Posted: Fri Mar 05, 2010 1:11 pm Post subject: |
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| Quote: | | So basically when timing is added it is most likely that the power actually starts to drop before there's detonation/knock? |
No not necessarily. Professionals tune engines to what is called MBT (minimum best torque) timing. The traditional way of doing it, was to find the maximum possible power, and then dial back timing until power dropped about 1%. That ensures that the engine is running on the safe side of the power curve. It adds substantial safety at a very small price in power. A tune that is perfectly safe for a given set of conditions of wide open throttle lasting 10 seconds can cause fatal detonation damage at 12 seconds of wide open throttle due to heat build up in the engine. Proper "safe" tune depends on actual usage conditions, not just some abstract fuel air mixture and ignition timing.
Burn speed on E85 fuel air mixtures varies much more that burn speed in gasoline, so small changes in fuel air mixture can effectively change your ignition timing.
Here in the Rocky Mountain West you see this sort of change all the time during the summer. A tune that is perfectly safe around town, kills the engine while towing a load over a pass due to the duration of the load. The same thing happens at Bonneville salt flats. There are a lot of racers that lose their engines near the 2 mile mark on their first pass, on a tune that was "safe" on the dyno, but due to the long term continuous load on the salt, they pushed the engine over the edge because they were on the back side of the power/ignition advance curve. They either push it into pre-ignition, or detonation (or one leading to the other) as heat builds up in the engine.
The timing that "feels best" on the street to your butt dyno, is almost always over advanced for heavy load. The engine feels great under brief periods of acceleration but under heavy continuous load it will eat itself.
Once you get near peak power, additional ignition advance gives you very little increased power at a huge cost in peak cylinder pressures and bearing loads, and drastically cuts your safety factor. If you go too far in that direction, you can kill any engine so fast you won't have time to lift throttle before the damage is done.
| Quote: | | I'm going 3.4l stroker on my supra and upping the compression ratio from 8.5:1 to 9:1. You think I would still be able to run as much timing/boost as before with E85? Probably 30-35psi is the max boost I'd use. |
No! Studies done by NACA back during the period of WWII on highly supercharged aircraft engines showed a very strong relationship between cylinder pressure and intake air temperature and detonation. Increase either one and your likelihood of detonation goes up (for a specific engine)
Due to the higher compression ratio, the engine will have higher thermal efficiency (likely to make more power) but it will probably do it at lower boost than the lower compression block, and have a narrower window of safe timing and fuel air mixture. As you build boost the safe window in both ignition timing and fuel air mixture gets narrower and narrower, until you are on the ragged edge of detonation.
On naturally aspirated engines, max safe power (just short of knock) is usually about 2-3 degrees retarded from maximum power.
The one major difference is, aircraft usually leave ignition timing alone at a factory recommended setting that will produce peak safe power and juggle fuel air mixture, where performance car guys frequently find a good fuel air mixture and then try to screw with the timing more often than the AFR (although modern electronic engine management is changing that). There is only one ideal ignition timing for a given engine and fuel air mixture, and it is the timing that puts peak cylinder pressure at about 12-14 degrees ATDC. This is why general aviation use fixed timing, and fiddle with fuel air mixture only.
http://www.highperformancepontiac.com/tech/0212hpp_spark_plug_advance/photo_04.html
Some of the very best technical data on engine tuning and supercharged engines under high load is in the aviation industry. There are several really good articles on the subject but you have to take a bit of time to get familiar with some aircraft terminology like LOP and ROP. In aviation they tune fuel air mixture based on cylinder head temperature and refer to ROP (rich of peak) and LOP (Lean of peak) meaning tuning the fuel air mixture so that the cylinder head temperature is so many degrees above or below the peak cylinder head temperature, since they can monitor cylinder head temperature and adjust fuel air mixture in real time while in flight. Unfortunately water cooled engines do not change cylinder head temperatures much but EGT and power change much the same in our engines and you can learn a lot by understanding how engine temperatures, EGT temps and power levels, ICP (internal cylinder pressure) change as you adjust mixture and timing.
http://www.mooneyland.com/lean_of_peak.htm
http://www.avweb.com/news/savvyaviator/savvy_aviator_59_egt_cht_and_leaning_198162-1.html
http://www.avweb.com/news/pelican/194452-1.html
Note in the above link how flat the power curve is near peak and how internal cylinder pressure, cylinder head pressure and EGT change near peak power. It is almost impossible to find peak power (even for professionals with first rate dyno setups). By the time you think you are at peak power you are usually far to the right where power drops off, when you should be tuning far to the left where power drop just becomes noticeable for maximum engine life at high power.
http://homepage.mac.com/ghim/Bearhawk/page13/files/Mixture%20Magic.pdf
http://www.avweb.com/news/pelican/182132-1.html
Bottom line is I would recommend you narrow down your fuel air mixture to a good max power AFR and then adjust ignition advance until you think you have reached max power, then retard the ignition (usually 2-3 degrees) until you can just detect a small drop in power. That is the MBT timing for that specific engine. Then dial in the AFR the last little bit.
Most people over use ignition advance.
Larry |
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