Boost tuning today, big backfire/died, also temporary lifter clatter
02-26-2008, 02:25 PM
#21
Being sluggish, wouldn't be because of the 15 degrees of timing. It's more than likely the A/F is rich on spool-up.
You actually want the A/F to 'ramp' down to 11.5:1 (or whatever your target is) as boost increases. In other words, seeing 12.8:1 with 1-2psi, is okay. Richening up to your target A/F by about 5psi.
You actually want the A/F to 'ramp' down to 11.5:1 (or whatever your target is) as boost increases. In other words, seeing 12.8:1 with 1-2psi, is okay. Richening up to your target A/F by about 5psi.
My normal PE is 12.8.
Boost PE (the way I've set it up in the Boost PE table in my tune):
12.8 at 1psi, 12.2 at 4psi, 11.7 at 8psi, 11.1 at 12psi
You can see that PE ramp playing out in the hptuners scan chart view back in post 15.
I haven't seen any problem with spooling up when going down the road, it's already making boost at 50% throttle depending on load, and it comes on pretty quickly.
Checking the log again, to get some objective numbers, it went 0-10 psi in 1.9 seconds, at 60%-80% TPS. Felt faster than that... Not sure if there's a lot of room for improvement there or not. Would be interesting to see what happens at 100% TPS.
Last edited by John_D.; 02-26-2008 at 03:53 PM.
02-26-2008, 03:07 PM
#22
LS1Tech Co-Founder
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John, 13 psi + 93 pump + 24 degrees of timing is risky. You will find that a lot of folks running say 12-17psi on pump are running like 15 -18 degrees of timing at WOT, I've seen some folks post that they were even running 12-13 degrees.
What do your inlet air temps look like?
What do your inlet air temps look like?
02-26-2008, 04:59 PM
#24
TECH Addict
you sure your knock sensors are working?
I have seen them go both ways, either way to sensitive or not register squat even when I can hear audible knock.
Pull some plugs after a run and verify they look good with no signs of detonation and have a passenger with "knock tuned ears" ride shotgun. Just because the computer is saying no knock doesn't mean your not detonating. Just like everyone else is saying, thats a crapload of timing for that much boost.
I have seen them go both ways, either way to sensitive or not register squat even when I can hear audible knock.
Pull some plugs after a run and verify they look good with no signs of detonation and have a passenger with "knock tuned ears" ride shotgun. Just because the computer is saying no knock doesn't mean your not detonating. Just like everyone else is saying, thats a crapload of timing for that much boost.
02-26-2008, 05:34 PM
#25
Good point. I'll check the plugs out.
I can also add 5 degrees of timing on the low end and see if I can get some knock down low where it's not so dangerous, to see if the sensors are responding. Sensitivity, decay, etc. are still set the same as stock.
I can also add 5 degrees of timing on the low end and see if I can get some knock down low where it's not so dangerous, to see if the sensors are responding. Sensitivity, decay, etc. are still set the same as stock.
02-26-2008, 08:01 PM
#27
I don't know exactly. When I was talking with the SDPC folks I told them I wanted something for boost, around 9:1, using first generation TEA 5.7 heads that were not milled, on stock graphite gaskets. The pistons have a big dish in them.
The engine did not come with a build sheet. There was some turnover at SDPC as the engine was getting finished up, and all I got was an invoice. I don't know the exact dish or the exact compression ratio.
The engine did not come with a build sheet. There was some turnover at SDPC as the engine was getting finished up, and all I got was an invoice. I don't know the exact dish or the exact compression ratio.
02-26-2008, 08:23 PM
#28
We've spent a lot of time in here talking about the timing advance, and I do need to verify I'm in the right range.
As far as the backfire, after thinking more about it, I'm leaning toward the big timing drop through the shift. With all the fuel I've added as I've increased the timing advance, I think the timing suddenly dropping from 22 degrees to 4 degrees loaded up the exhaust system with fuel. Then when the timing ramped back up, 3/10's of a second later is when it backfired and the engine died. This is the first time I've had an upshift under any significant amount of boost, and it's the first time it's ever backfired on me.
About the lifter noise, I don't know. Maybe I've got a weak lifter in the bunch... I'm going to do a fresh oil change and see if the problem comes back.
This oil is slightly fuel diluted from some earlier tuning when my WB sensor was on the way out and I was running way too rich but the WB was reporting way lean. The sensor could handle any NA load, and the first couple of seconds of boost too, but then went straight to 50:1 on me after that, no matter how much (or how little) fuel I threw at it. I chased that one for two weeks before realizing it was the sensor. Ended up running all the way up to 210% VE at one point, before getting a grip and figuring out my instrumentation had to be bad.
As far as the backfire, after thinking more about it, I'm leaning toward the big timing drop through the shift. With all the fuel I've added as I've increased the timing advance, I think the timing suddenly dropping from 22 degrees to 4 degrees loaded up the exhaust system with fuel. Then when the timing ramped back up, 3/10's of a second later is when it backfired and the engine died. This is the first time I've had an upshift under any significant amount of boost, and it's the first time it's ever backfired on me.
About the lifter noise, I don't know. Maybe I've got a weak lifter in the bunch... I'm going to do a fresh oil change and see if the problem comes back.
This oil is slightly fuel diluted from some earlier tuning when my WB sensor was on the way out and I was running way too rich but the WB was reporting way lean. The sensor could handle any NA load, and the first couple of seconds of boost too, but then went straight to 50:1 on me after that, no matter how much (or how little) fuel I threw at it. I chased that one for two weeks before realizing it was the sensor. Ended up running all the way up to 210% VE at one point, before getting a grip and figuring out my instrumentation had to be bad.
02-26-2008, 08:34 PM
#29
I have rattled the engine pretty hard a couple of times trying to beat this but it's just the limits. I now run 11.5 lbs & meth with 13 degrees & it's pretty bomb proof. I have the dual gate boost controller as well & I do 15/16 lbs for 1 gear blasts (not 3rd) when I have to.
I have a 9.4 to 1 compression ratio & my car makes some great power at 11.5 psi.
It may be the gasoline in my area I don't know.
02-26-2008, 08:38 PM
#30
Couple of other pieces of information that may or may not be interesting to anybody following this thread.
Cam is a 224/228 .581/.588 on 115.
Mac mid's. (seem to work ok...)
An STS-provided '67' turbo that went to Jose in AL for a rebuild when I blew the swap engine almost 3 years ago and sent a bunch of piston(s) through the original spooled up turbo. While Jose had it, it got a new/improved cold side wheel and housing that make it "basically a 70".
LS6 intake, the whopper fmic, 3" tubing from the k-member forward, bigger filter and tubing to the turbo, bigger tubing over the axle, borla xr-1 after the turbo.
Car has just hit the road again in December. Was on jackstands nearly all the rest of the time after the old engine blew.
Cam is a 224/228 .581/.588 on 115.
Mac mid's. (seem to work ok...)
An STS-provided '67' turbo that went to Jose in AL for a rebuild when I blew the swap engine almost 3 years ago and sent a bunch of piston(s) through the original spooled up turbo. While Jose had it, it got a new/improved cold side wheel and housing that make it "basically a 70".
LS6 intake, the whopper fmic, 3" tubing from the k-member forward, bigger filter and tubing to the turbo, bigger tubing over the axle, borla xr-1 after the turbo.
Car has just hit the road again in December. Was on jackstands nearly all the rest of the time after the old engine blew.
02-26-2008, 11:48 PM
#31
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I was only able to run 14* on my car without meth, 18 with @ 15 psi....over 22* should only be tried when you KNOW where things are. The fact that it still runs after backfiring @ WOT is a VERY good sign! That usually reults in serious carnage (like the plastic intake goes away). Not that I would know.....
03-19-2008, 01:36 PM
#32
I got the piston CC information from SDPC, and 405HP_Z06 (Aaron) was kind enough to plug in all the details into a compression calculator.
Based on the information we had to work with, I'm running 8.7 static, 6.8 dynamic.
I also found that when I "sensitized" the knock sensors by turning the gain up from 1 to 4, that actually desensitized them.
So I'll be making a couple more tuning runs with them set back to the stock gain settings and see what happens as far as KR.
Looks like 8.7 needs a lot of timing, especially with a low IAT.
Based on the information we had to work with, I'm running 8.7 static, 6.8 dynamic.
I also found that when I "sensitized" the knock sensors by turning the gain up from 1 to 4, that actually desensitized them.
So I'll be making a couple more tuning runs with them set back to the stock gain settings and see what happens as far as KR.
Looks like 8.7 needs a lot of timing, especially with a low IAT.
03-22-2008, 08:06 AM
#33
Update:
1. No backfire through the shift with less torque management retard. New transmission is here, and torque converter is coming next week. Then I will eliminate torque management completely.
2. Lifter did not clatter anymore after oil change. Old oil was thinned down a bit from fuel from running rich on boost during previous tuning.
3. Resensitizing the knock sensors (lowering the "gain") shows 1 to 2 degrees of KR showing up, but only sporadically, at the timing settings I had.
4. Addressing the KR by
a) lowering the timing overall
b) using Spark Control, Spark Correction, AFR Correction to reduce timing as boost increase
(this works because I have the AFR slowly and steadily going richer as the boost climbs, so I can also use that richer commanded AFR to reduce timing)
5) It's breaking up a bit on the top end, possibly blowing out the spark. Will be reducing the plug gap from .035 to .030 to see if that solves it. The breaking up may have been contributing to the KR I was seeing too.
1. No backfire through the shift with less torque management retard. New transmission is here, and torque converter is coming next week. Then I will eliminate torque management completely.
2. Lifter did not clatter anymore after oil change. Old oil was thinned down a bit from fuel from running rich on boost during previous tuning.
3. Resensitizing the knock sensors (lowering the "gain") shows 1 to 2 degrees of KR showing up, but only sporadically, at the timing settings I had.
4. Addressing the KR by
a) lowering the timing overall
b) using Spark Control, Spark Correction, AFR Correction to reduce timing as boost increase
(this works because I have the AFR slowly and steadily going richer as the boost climbs, so I can also use that richer commanded AFR to reduce timing)
5) It's breaking up a bit on the top end, possibly blowing out the spark. Will be reducing the plug gap from .035 to .030 to see if that solves it. The breaking up may have been contributing to the KR I was seeing too.
