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C6 Corvette ZR1 & Z06General info about GM’s Corvette Supercar, LS9 Corvette Technical Info, Performance Upgrades, Suspension Setup for Street or Track
Keep in mind that is point of MBT. Many times people purposely do not run at MBT values. It is more so interesting (for my value) to see what they specify at WOT. Stock LS7 follows the 0.96 line across...which is about 22 deg timing. This aligns with the stock HO timing table after all PE adders are taken into account perfectly. I am sure it is no coincidence that "tuners" also set their timing tables similar and see no power going higher (on 93 and standard compression).
Pulled the plugs out and swapped to TR7IX. Prior to this I had two long highway cruises (2.5h each way). Guessing that is what cleaned up the plugs so much compared to my pic a couple replies up. Could also be the catch can doing its thing...
LS7, mamo msd, Katech K501, milled 0.030" heads, ARH headers, tr6ix plugs, etc the works. Live at sea level and will see 101-102kpa days. Runing E10 94 @ 0.82 lambda. 92% duty cycle. Airflow calcs put it at ~600whp @ 7000 and 500tq at 5000.
Seems I am about 4 deg across the board lower timing than other tunes. I did not desensitize my knock sensors as they are there for a reason IMO.
I also road race so it builds up a lot of heat - want to make sure its safe but dont want to leave a lot of power on the table.
Even with this timing map I get blips of 0.5-1kr.
1.04g/cyl @ 4000, 1.12 @ 5000 1.0 @ 7000 so seems to be making jam...put the line in there for reference.
Thoughts? Normal?
Thank you!
I meant to give you my timing table form the 1/2 mile race where I was tuning earlier to compare with (this one is isn't my final timing table but is from the fastest run). The bottom is a log of the 1/2 mile run. I also have water/methanol spraying progressively starting around 4000 rpms. This was a 164+ mph pass log. Funny thing is I could add more timing without picking up any more KR with the sensors "numbed" but didn't pick up any more mph so I only added timing where the mph was improved. Maybe "numbing" the sensors isn't helping.
I hope you get things figured out.
Last edited by MickVette; 09-19-2018 at 07:25 AM.
Reason: more info
Thank you for the post and information - very helpful. It looks like you are basically running a stock timing table (once the fuel spark adder gets tagged onto the standard table.)
Stock ls7 runs a flat 22deg 3k-6k then goes 24-25deg till redline.
Some of my timing will be pulled due to shaving the heads and will probably make more power with less...16 just seems low.
Thank you for the post and information - very helpful. It looks like you are basically running a stock timing table (once the fuel spark adder gets tagged onto the standard table.)
Stock ls7 runs a flat 22deg 3k-6k then goes 24-25deg till redline.
Some of my timing will be pulled due to shaving the heads and will probably make more power with less...16 just seems low.
16° does seem low.
For comparison data: My engine has 12.0:1 CR 93 octane and a water/methanol mix. I calculated the actual octane at WOT to be about 94.7 so I guess that is allowing the stock'ish timing numbers with the higher CR. I parked my car for a while and to help the fuel stay longer I ran the tanks near empty and put non-ethanol 90 octane with stabilizer. I did pick up 2-3° of KR with that fuel even spraying the water/methanol. I'm still trying to run that stuff out of the tanks, even after a few fill ups I still see some KR. I might have to spring for some 100+ octane race gas for a tank full to even things back out.
So all that talk from me to ask if maybe you got a bad batch of fuel to tune with?
Plugs gapped correctly? Try one range colder yet? I'd put TR7's in for ***** and giggles and see if that makes a difference...
Bit of an update. Installed the TR7IX, oil catch can cleaned out, 65f outside and did some logs. Still getting knock so unfortunately the plugs did not help nor did moving the oil line from the header (well...other than not starting a fire!).
Looks like nature of the beast is to take lower timing. I know these are ricer calculations but I am hitting 1.10g/cyl peak tq ~495wtq, 1.02g/cyl ~460wtq at 6800 which puts me around 595whp. Injectors are at 92% on E10 at 7k. Maf hits 60lb/hr.
Thing that bothers me is I can do 3 identical pulls and KR is different. Most of the time there is knock at 4200 rpm (right when the poweband starts to climb hard), and 6000rpm (that weird area between tq falling off and cyl head wanting to keep going).
Knowing I am probably riding along max spark for my setup I reduced those areas more and then took an extra degree out of the whole map for good measure.
Technically speaking, +- 4deg around MBT is ~1% loss both ways.
I will leave this open for discussion but after how much KR do you consider safe before pulling back timing? 0.5? 1? 2?
I am now running with no KR...but it is not the most agressive timing map around.
I just ran into a similar situation. Stock LS7 with ARH's and MF103 as only mods. Wanted to dial in the MAF curve and see where I was at. Don't have tables in front of me but I noticed when I leaned out the PE curve from factory I picked up .5 to 1.5 KR right around 4400-4800. Factory seems to run them real rich at peak torque, ~.7 lambda if I recall. Don't know what your PE table looks like but you might want to try to go richer at peak torque which might allow you to up the timing.
Try gapping down the plugs if you are running stock gap. I know when I went to milled heads and MSD intake I was getting a little knock and reducing the gap fixed that.
No, those typically run too hot and can cause kr in even a stock motor.
I've read quite a bit of conflicting info on this. Some people go from stock to TR6ix/TR7 and clean up their knock issues, and some go the other way (back to stock) to clean up their issues. FWIW the ZR1 also runs the same plugs which is boosted and has over 100 more hp.
My tables look similar to yours if not worse, but I'm on cali 91 octane gas. I'm also running .82 lambda at WOT, are you about the same?
Try gapping down the plugs if you are running stock gap. I know when I went to milled heads and MSD intake I was getting a little knock and reducing the gap fixed that.
Technically speaking...a lower gap "reduces" the speed of the flamefront due to a smaller kernel which is similar to reducing timing a smidge. So I could see why this helped.
From a "physics" standpoint 0.82 lambda gives you best torque.
Now with what you said if you can get an extra 2deg timing running richer (torque starts to fall off when richer than 0.82) do you make up for that power loss and then some? Or are you better off with less timing and less fuel?
This is the $1,000,000 question.
Originally Posted by psmith23
I just ran into a similar situation. Stock LS7 with ARH's and MF103 as only mods. Wanted to dial in the MAF curve and see where I was at. Don't have tables in front of me but I noticed when I leaned out the PE curve from factory I picked up .5 to 1.5 KR right around 4400-4800. Factory seems to run them real rich at peak torque, ~.7 lambda if I recall. Don't know what your PE table looks like but you might want to try to go richer at peak torque which might allow you to up the timing.
Good point on the ZR1. They also run richer which would help cool the chambers down more which may be how they get away with it?
I am running 94 e10 at 0.82 lambda as well (want to make use of that flame speed).
How much lower are you? I get the most KR activity at 4000, 5000, and 58-6000.
Originally Posted by ssbowtie1
I've read quite a bit of conflicting info on this. Some people go from stock to TR6ix/TR7 and clean up their knock issues, and some go the other way (back to stock) to clean up their issues. FWIW the ZR1 also runs the same plugs which is boosted and has over 100 more hp.
My tables look similar to yours if not worse, but I'm on cali 91 octane gas. I'm also running .82 lambda at WOT, are you about the same?
I don't have the PCV lines hooked up to my air intake or intake manifold. Oddly, I have a thin oil film coating inside the plenum and runners of my Holley Hi Ram. Not sure how that got there.
09-14-2018, 09:31 AM
