Lil Blacky’s official TVS build thread(long post)
05-01-2018, 11:28 AM
#576
Just looking at what you did and what you didn't do that would keep the issue there and in the same valve relief corner, although it looks like the other relief was starting to let go.
Forged pistons also... That sucks. My new set is costing $900.00 I have a like new set for a standard bore size.
Are you going to get some lower compression pistons this time?
Forged pistons also... That sucks. My new set is costing $900.00 I have a like new set for a standard bore size.
Are you going to get some lower compression pistons this time?
Last edited by Henry3959; 05-01-2018 at 11:51 AM.
05-01-2018, 12:12 PM
#577
Senior Member
Thread Starter
My friend has some je 2.4 pistons for me. They are lower than our stock compression. 9 something. And I’m sending my old stock block to Trevor jolley to get sleeved
05-01-2018, 12:46 PM
#578
Nice... My pistons were suppose to have arrived at 3.466 and they came at 3.461 making a new sleeve a 3 1/2 thousandths clearance so they are going back. In speaking with diamond and 3 Denver engine builders, they all recommend .003 to .0035 clearance for my app.
05-01-2018, 06:22 PM
#583
Looks like you have something going on with #3 cam lobes or springs thats making some sort of difference. Just because it "looks" okay doesnt mean you cant give it a quick mic to be sure. I would also check your valve spring tension to see if one is weaker than the others.
05-01-2018, 10:09 PM
#584
You need to figure out the root cause or you are setting yourself up for it for the 3rd time. I've been around engines for 35 years and I've seen too many that end the same as before due to not changing anything and hauling it up to a chance occurrence.
Honestly having the motor blue printed or something wouldn't hurt. We used to build small block chevys and every time would Clay the pistons to check clearance, like the one I put in my Nova. Are you thinking that it went lean or what? It shouldn't have gone bad in less than 5,000 miles. If you throw it back together without changing things you can expect the same outcome. Been there done that and it gets expensive.
Honestly having the motor blue printed or something wouldn't hurt. We used to build small block chevys and every time would Clay the pistons to check clearance, like the one I put in my Nova. Are you thinking that it went lean or what? It shouldn't have gone bad in less than 5,000 miles. If you throw it back together without changing things you can expect the same outcome. Been there done that and it gets expensive.
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Henry3959 (05-01-2018)
05-02-2018, 12:04 AM
#585
my .02:
that to me looks like high cylinder temps caused that. going back to my top alcohol dragster days we would every so often burn a piston up like that, where it splatters aluminum all over the sleeve and if it gets real aggressive it will start to torch the head gasket out. when we looked at the data log we would always find that cylinder was over 1250*f on the pyrometer. the root cause was that cylinder leaned out for some reason, in our case was a plugged fuel nozzle or failed fuel hose (mechanical injection).
id be interested (i think most of us would) in some more info on when the failure happened. were you on the track or just having fun on the street? at a guess how long were you at full throttle for? also, what sort of air fuel ratios are you seeing, and roughly how much timing? i kind of have a theory in my head but i need a little more info, if you wouldnt mind sharing.
that to me looks like high cylinder temps caused that. going back to my top alcohol dragster days we would every so often burn a piston up like that, where it splatters aluminum all over the sleeve and if it gets real aggressive it will start to torch the head gasket out. when we looked at the data log we would always find that cylinder was over 1250*f on the pyrometer. the root cause was that cylinder leaned out for some reason, in our case was a plugged fuel nozzle or failed fuel hose (mechanical injection).
id be interested (i think most of us would) in some more info on when the failure happened. were you on the track or just having fun on the street? at a guess how long were you at full throttle for? also, what sort of air fuel ratios are you seeing, and roughly how much timing? i kind of have a theory in my head but i need a little more info, if you wouldnt mind sharing.
05-02-2018, 09:44 AM
#587
Senior Member
Thread Starter
They were brand new injectors. I was almost to the end of the track when it happened. I felt it slow down. When I glanced at the wideband going down the track it was reading low 12s which is what it’s set at. Running 20-21 degrees of timing. I was getting about 3 degrees of knock pretty much the whole way down the track. Iat2 temps weren’t hot. Had ice in the tank so it was pretty cold. And yes it obviously got hot. And I’m not using any of the same parts for the next one. The head, springs, valves and cams are getting replaced. I plan to get ID1000 injectors. I wouldn’t be surprised if the issue lies with the head somehow. I mean it’s all from 06 with 150k+ miles. It’s been beat on pretty bad.
05-02-2018, 02:15 PM
#588
to me, its lean. i know guys run ecotecs in the low 12s, but thats causing a lot of heat. the other thing is your car being an automatic is a little unique, the automatic loads the engine much different than a standard. during a 1/4 mile pass your wide open for 12 ish seconds, during that your cylinder temps/egts just climb, where is a manual trans car there is a short period where the load is taken away to shift, so the the temps will level off for a second before climbing. gm computers have a feature called piston protection, something most tuners turn off. piston protection adds fuel after you have been at wide open throttle for a certain amount of time (that time figure isnt a value we can change) to cool the cylinders down.
something that has to be considered is the intake manifold distribution. when monitoring air/fuel ratio in the collector its the average of the cylinders. intake manifolds never have exactly the same air distribution to every cylinder, and this results in some cylinders being richer or leaner than others. in reality when running at say 12.0:1 afr you may have 1 or 2 holes running at 11.5:1, and one running at 12.5:1. i havent seen actual flow data from the lsj intake manifold, but being you have had 2 engines fail in the same cylinder, id say the manifold has more air flow to cylinder 3.
another thing here is the knock retard. the ecm is protecting the engine by removing timing, however the engine was knocking for it to remove timing. i would tend to think the knock isnt caused by too much timing, but because the engine is lean. again, lean causes higher cylinder temps, and that causes detonation.
if your targeting low 12s afr and thats what its doing i would say there is nothing mechanically wrong to cause the failure, i would say the problem is the tune. myself, id be targeting 11.5:1 afr, you may lose a slight bit of power (likely not enough to feel) but the pistons would thank you for it.
something that has to be considered is the intake manifold distribution. when monitoring air/fuel ratio in the collector its the average of the cylinders. intake manifolds never have exactly the same air distribution to every cylinder, and this results in some cylinders being richer or leaner than others. in reality when running at say 12.0:1 afr you may have 1 or 2 holes running at 11.5:1, and one running at 12.5:1. i havent seen actual flow data from the lsj intake manifold, but being you have had 2 engines fail in the same cylinder, id say the manifold has more air flow to cylinder 3.
another thing here is the knock retard. the ecm is protecting the engine by removing timing, however the engine was knocking for it to remove timing. i would tend to think the knock isnt caused by too much timing, but because the engine is lean. again, lean causes higher cylinder temps, and that causes detonation.
if your targeting low 12s afr and thats what its doing i would say there is nothing mechanically wrong to cause the failure, i would say the problem is the tune. myself, id be targeting 11.5:1 afr, you may lose a slight bit of power (likely not enough to feel) but the pistons would thank you for it.
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Slowbalt2000 (05-02-2018)
05-02-2018, 02:45 PM
#589
Senior Member
Thread Starter
That’s what people run with e85. And I can tell quite a bit when the afr is mid 11s. Our e85 here changes from station to station. I’ve had e85 drop it to 10s and then a different store brings it back up. But if putting a little more fuel in is what I have to do then I will. And I’m also going to monitor temps in every single cylinder this time. Putting a sensor on each runner on the header.
05-02-2018, 02:47 PM
#590
Senior Member
Thread Starter
And also my tune is setup to not remove timing if it knocks. But I always monitor the knock. We did that because I was getting a ton of false knock. But that problem was fixed.
05-02-2018, 03:00 PM
#591
to me, its lean. i know guys run ecotecs in the low 12s, but thats causing a lot of heat. the other thing is your car being an automatic is a little unique, the automatic loads the engine much different than a standard. during a 1/4 mile pass your wide open for 12 ish seconds, during that your cylinder temps/egts just climb, where is a manual trans car there is a short period where the load is taken away to shift, so the the temps will level off for a second before climbing. gm computers have a feature called piston protection, something most tuners turn off. piston protection adds fuel after you have been at wide open throttle for a certain amount of time (that time figure isnt a value we can change) to cool the cylinders down.
something that has to be considered is the intake manifold distribution. when monitoring air/fuel ratio in the collector its the average of the cylinders. intake manifolds never have exactly the same air distribution to every cylinder, and this results in some cylinders being richer or leaner than others. in reality when running at say 12.0:1 afr you may have 1 or 2 holes running at 11.5:1, and one running at 12.5:1. i havent seen actual flow data from the lsj intake manifold, but being you have had 2 engines fail in the same cylinder, id say the manifold has more air flow to cylinder 3.
another thing here is the knock retard. the ecm is protecting the engine by removing timing, however the engine was knocking for it to remove timing. i would tend to think the knock isnt caused by too much timing, but because the engine is lean. again, lean causes higher cylinder temps, and that causes detonation.
if your targeting low 12s afr and thats what its doing i would say there is nothing mechanically wrong to cause the failure, i would say the problem is the tune. myself, id be targeting 11.5:1 afr, you may lose a slight bit of power (likely not enough to feel) but the pistons would thank you for it.
something that has to be considered is the intake manifold distribution. when monitoring air/fuel ratio in the collector its the average of the cylinders. intake manifolds never have exactly the same air distribution to every cylinder, and this results in some cylinders being richer or leaner than others. in reality when running at say 12.0:1 afr you may have 1 or 2 holes running at 11.5:1, and one running at 12.5:1. i havent seen actual flow data from the lsj intake manifold, but being you have had 2 engines fail in the same cylinder, id say the manifold has more air flow to cylinder 3.
another thing here is the knock retard. the ecm is protecting the engine by removing timing, however the engine was knocking for it to remove timing. i would tend to think the knock isnt caused by too much timing, but because the engine is lean. again, lean causes higher cylinder temps, and that causes detonation.
if your targeting low 12s afr and thats what its doing i would say there is nothing mechanically wrong to cause the failure, i would say the problem is the tune. myself, id be targeting 11.5:1 afr, you may lose a slight bit of power (likely not enough to feel) but the pistons would thank you for it.
100% agree, 12.0 afr might be considered "safe" but theres too many variables with street tuning for me to ever consider running that lean.
Alissa, running egt in every runner is a good idea. definitely let us know what they read when you get it running again.
05-02-2018, 03:24 PM
#593
I would do some tuning and testing with EGT but a 4 channel EGT without feedback to lower the temps isn't going to save the next cylinder.
I tuned our Nitro Methane 2 stroke land speed holding RS 50 with EGT and we could loose a piston on the dyno faster than you can shut the engine down. The actual temps in the cylinder are hotter than what's leaving the port with some delay in the thermo-coupler. Naturally nitro-methane is more volatile but even if you stare at the EGT's down the track and something goes south, it's all over but the crying.
I tuned our Nitro Methane 2 stroke land speed holding RS 50 with EGT and we could loose a piston on the dyno faster than you can shut the engine down. The actual temps in the cylinder are hotter than what's leaving the port with some delay in the thermo-coupler. Naturally nitro-methane is more volatile but even if you stare at the EGT's down the track and something goes south, it's all over but the crying.
05-02-2018, 11:02 PM
#595
That’s what people run with e85. And I can tell quite a bit when the afr is mid 11s. Our e85 here changes from station to station. I’ve had e85 drop it to 10s and then a different store brings it back up. But if putting a little more fuel in is what I have to do then I will. And I’m also going to monitor temps in every single cylinder this time. Putting a sensor on each runner on the header.
on gasoline with water/meth i myself target .75-.8 lambda for a safe tune, thats around 11.0:1-11.8:1. theoretical best power on gasoline is .85-.9, or 12.5 to 13.2:1, however running that lean will cause high cylinder temps and cause engine damage. e85 has a much wider range for theoretical max power, .70-.85 lambda, that would display 10.5-12.5 on a gasoline calibrated wideband. again, when you go to the leaner side of things is causes higher cylinder temps, and damage. i havent done much with e85 myself, but we have done a number of cars on e85 in our shop, ill have to check with our tuner but im fairly certain he targets around 11.0:1 for a safe e85 tune.
if your e85 has that much variance you need to compensate for it somehow. ive read how people keep a test kit in their car so when they fill up they can test the ethanol content before filling up. alternatively you can put an ethanol content gauge in the car. you could tune the car for say, e70, and when you fill up if the ethanol content is higher splash some gas in to bring it down closer to 70%. or, you could work out some different tunes for varying ethanol content.
