2020 LT1 SS, super weak on dyno trying to figure out issue

That sounds like some junk TSP cam specs.

I had a car over a decade ago do something similar with all brand new valve train parts. Turned out the cam was too big on lift for the valve spring package. Parts were not bought as a complete setup. Cam from one company, spring package from another.

Looked like your dyno graph, just higher. Also had bad knock retard with low to reasonable ignition advance. Upon disassembly and inspection the interference was enough to cause really bad valve tip wear in no more time than a handful of street miles and then a small number of dyno pulls.

I think you and I have shared a hatred for TSP valvetrain products for some years now. The Tsunami cam, jeebus what a headache lol

Well, after finding some things - some burnt looking plug wires, pinned against the headers, LTR5IX plugs that looked crusty and were apparently reused when the motor was pulled out to do the cam (and oddly orange like torco had been used on them or something with MTBE) I put different wires and new LTR6IX plugs in the most troublesome seeming cylinders. I never used heat range 5 plugs in bolton 10:1 compression LS1s making 350, so 12:1 LTs making 500 I feel like should take a 6 minimum?

Also did compression test on #2 #3 and #5 all were 220s

Anyway, first pull on E66 made @515, and no more obvious dip. I mean it looks like the valvetrain or SOMETHING isnt quite happy, its an unnatural fall off from peak that doesnt gently roll over its a straight slide but marked improvement.

Ive heard about 2019+ cars hitting the ABS during 5 or 6th gear pulls (Ive been doing these in 5 so far) what fuse is the right one to pull to make sure thats not happening? I actually logged all the ABS/brake channels I could find yesterday at one point thinking that might be it before seeing posts about the newer cars doing it

Run22 is latest, other one is with the brake channels I logged

Can you post the graph? Overlaid with the previous?

Graph

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Originally Posted by edcmat-l1

Can you post the graph? Overlaid with the previous?

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Can see a subtle dip, but not the chunk out like all the previous

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Originally Posted by GrannySShifting

Can see a subtle dip, but not the chunk out like all the previous

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Definitely follows the same pattern. The HP jump looks like it could be due to A/F difference also. Can you post the .wp8 file?

Either way good deal on picking up a chunk. Still looks like it falls off like something isn't happy.

I would pull a cover and double check the springs. These motors take special valve springs. I've seen them coil bind so bad that they wiped out the guides within 10 to 15000 miles. Also seen new ones break as previously mentioned.

No chance you have the A/C or defrost on? These will engage the compressor at high RPM/ WOT and the dip looks similar.

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Originally Posted by Alvin

No chance you have the A/C or defrost on? These will engage the compressor at high RPM/ WOT and the dip looks similar.

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Alvin you know - I never thought of that because all the older gen ECU turn them off automatically under load, but no climate is off

if you set the disable to 4000 and reanable to 3950 does that shut it off, or do you have to do TPS too (set to 200%/197%)

So, this is fun. 2020 Camaro SS, with both ABS fuse and j case square fuse pulled, in 5th gear must jerk the brakes to make that dip. Doesnt do it in 6th for WHATEVER reason (although reads a few hp lower in 6th). I smelled the rear wheels after back to back to back pulls and def smells like something getting hot/funky

In summary, Im not crazy LOL

While were all having fun in here, lets talk injector SOI and alcohol offset. What are you typically doing for this, if it likes say 360 on pump gas what are you finding on 85% ethanol?

Also, little wierd thing I encountered, it made 515 with 66% ethanol in it, and only 495 with 80%. Timing pretty much same, I dont SEE anything wrong with SOI/EOI ending up too late with the higher fill of alcohol but I ALSO noticed that the pulsewidth was little LESS at 6000rpm say - it was leaner (13.1 vs 12.6) even though target air/fuel reflected HIGHER alcohol content and everything??

I don't back SOI up for Ethanol vs Gas as long as I'm not running out of spray window. As for the Lambda changing, if you used the LT4 injector density table, that would be why. Pay attention to Injector Tip Temp as the LT4 table will add/remove up to 4% fuel at WOT depending on temp. Your dyno runs had different Injector Tip Temp values in the log.

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Originally Posted by TriPinTaZ

I don't back SOI up for Ethanol vs Gas as long as I'm not running out of spray window. As for the Lambda changing, if you used the LT4 injector density table, that would be why. Pay attention to Injector Tip Temp as the LT4 table will add/remove up to 4% fuel at WOT depending on temp. Your dyno runs had different Injector Tip Temp values in the log.

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Thats what I was thinking, why they have the offset numbers all over the place from the factory beats me, Ive zero it out

Hadnt thought to look at that, these runs were 1.012 and 1.000 that multiplier will do that much change?? Def saw alot more than 1% change in A/F highest to lowest mPa and ITT youd see WOT is 1.013 to 1.00 range.

The LT1 table is pretty much 1.00 everywhere WOT. Best to just use a LT1 table then, ever see a reason to use the LT4 table anywhere or you use LT4 table and make the WOT section all 1.000?

It really needs to be dialed in. A .001 is a 1% change ;) Higher numbers leaner. Lower richer. I find the offset to be necessary on trucks. Helps tremendously with high load, low rpm spark knock and being able to run more timing. Even on stockers set up from the factory for ethanol it helps to change it or increase it. That's what I've found anyway.

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Originally Posted by GHuggins

It really needs to be dialed in. A .001 is a 1% change ;) Higher numbers leaner. Lower richer. I find the offset to be necessary on trucks. Helps tremendously with high load, low rpm spark knock and being able to run more timing. Even on stockers set up from the factory for ethanol it helps to change it or increase it. That's what I've found anyway.

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How does Injector Density table help being a ITT vs Rail Pressure table on high load low rpm spark knock?

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Originally Posted by GrannySShifting

So, this is fun. 2020 Camaro SS, with both ABS fuse and j case square fuse pulled, in 5th gear must jerk the brakes to make that dip. Doesnt do it in 6th for WHATEVER reason (although reads a few hp lower in 6th). I smelled the rear wheels after back to back to back pulls and def smells like something getting hot/funky

In summary, Im not crazy LOL

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Ought to hit em with the temp gun to see what they read. Should be able to hit the rotors through the rims.

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Originally Posted by GrannySShifting

Thats what I was thinking, why they have the offset numbers all over the place from the factory beats me, Ive zero it out

Hadnt thought to look at that, these runs were 1.012 and 1.000 that multiplier will do that much change?? Def saw alot more than 1% change in A/F highest to lowest mPa and ITT youd see WOT is 1.013 to 1.00 range.

The LT1 table is pretty much 1.00 everywhere WOT. Best to just use a LT1 table then, ever see a reason to use the LT4 table anywhere or you use LT4 table and make the WOT section all 1.000?

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I use the LT4 table and then set WOT to 1.00 on NA LT1's that use LT4 fuel parts. I don't know if that is the "correct" way to do it but I found it easier. There may be a little bit of part throttle and idle adjustment to the table if you want to make it perfect but it will work fine without doing that. I found it easier than trying to keep the LT1 table with LT4 injectors. The Lambda and fuel trims were all over the place at part throttle and idle using the LT1 table.

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Originally Posted by GrannySShifting

Alvin you know - I never thought of that because all the older gen ECU turn them off automatically under load, but no climate is off

if you set the disable to 4000 and reanable to 3950 does that shut it off, or do you have to do TPS too (set to 200%/197%)

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I have no idea if that works as it should.

I've had a couple I forgot to turn the AC off and instead of making an entire pull down on power like a GEN 4 these got up high in the RPM before the compressor came on.. Which gave it a odd graph.

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Originally Posted by GrannySShifting

How does Injector Density table help being a ITT vs Rail Pressure table on high load low rpm spark knock?

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Was referring to the alcohol offset for that one.

The density table will keep your trims and wot fueling in general dialed in to the T so to speak. You can actually dial it in to the point of keeping trims averaging less than a 1% error in your MAF curve if you get good enough at it for both regular driving and wot runs. I dial in driving then have customers do cold start repeated high load burst to dial in the afr's for wot. After doing so a couple of times all fueling should stay less than or around a 1% error. The density table also seems to be engine specific more so than injector specific as it won't change so much for injectors, but for the engines directly from all of the OE calibration stand points I've seen running the same injectors with different engines.