hrcslam

I bring this up because my timing tables are much lower than the stock ones. Is this normal?

See sig for build details.

My timing tables:



The most timing I see on at over 80kPa and 4000rpms on data logs is 34° advanced, and this is very rare. 32° advanced is common over 4500rpms @ more than 80kPa though.

I've changed a lot to my tune since my last dyno tune. My O2 popped out and it went to SD mode and ran like utter crap after my dyno tune. So after fixing the O2 (new bung and O2) I did a SD tune then a MAF tune. My VE tables look completely different than my Dyno tuner did, and my MAF tables changed too. But, I didn't change my spark tables.

Basically, my dyno tuner changed my VE tables based on BLM's with the MAF plugged in, then adjusted WOT AFR with his wideband using the AFR % Change @ WOT tables. I ended up changing the VE tables a lot from what he did, then had to adjust the WOT AFR tables down using math (no wideband).

I haven't changed the Spark tables though and I haven't seen any real knock. To clarify, I'm getting false knock. I determined that by maxing my max spark advance at 25°. Then I did a data log and saw the exact same amount of random knock counts and retard. I haven't been able to address this issue yet (exhaust is hitting frame), but have pulled knock retard down a lot in the tune. I know I know, not a good idea.

My question is, for my Compression ratio (11.6:1) on LE2 ported heads with my build am I leaving power on the table at 30-34° WOT over 4000rpms? Hopefully I can get it back to the dyno in a month or so, but is it worth adding timing and data logging it before then?

PA94Z

iTrader: (1)

How are you adjusting afr without a wideband? Narrow band of sensors are not accurate enough. To properly tune a maf car you should first tune in speed density adjusting ve tables. Then tune maf tables. I'm no expert but tuning ve tables with the maf still in play seems like the wrong way to do it.

30* is conservative. Is the tuner familiar with lt1s? if you get the spark tables close on the dyno you can fine tune at the track. Increase spark advance until mph stops gaining or drops off. Then back it off 1-2 degrees.

hrcslam

Yeah, I did it with the BLM's. Not the best method I know, but I don't have a wide band and my Dyno tuner has no idea what he's doing on my LT1.

You're right he shouldn't be adjusting the VE tables with the MAF plugged in. But I took it to him cause he was the tuner and I was still learning. Thanks to websites like this and LS1LT1.com I learned the err of his (and my) ways.

I got the BLM's to stay right at 128 throughout the tables in SD mode, I had to "disable" PE mode to do it though. Then I re-connected the MAF and adjusted the MAF calibrations until the BLM's were steady at 128 again. Then re-enabled PE mode. I then adjusted my AFR correction @ WOT tables using a calculator I made on Excel and monitored Knock counts the entire time. I should be at 12.1:1 to 12.49:1 AFR at WOT now; assuming, of course, 128 is actual 14.7:1 AFR. I don't want to push it leaner without the wide band though.

Now I'm up to spark timing and wondering how bad my tuner messed those up to.

bowtienut

iTrader: (1)

That would be the LOWEST high-MAP timing values I've ever seen for a properly tuned NA setup on LT1's.
Did your "dyno tuner" set the tables to these values? I wouldn't call him a dyno tuner if he just set it to ridiculously safe levels and then tuned A/F only.
Only if you've advanced your cam and therefore biased the Opti reference could I imagine this being right.
My car wants 29 WOT timing in the tables, and that's the lowest I've ever heard of. Most high compression builds with good heads seem to like 30-32.

moehorsepower

iTrader: (3)

Thats good timing for around a 150 shot. and that A/F is way too rich for an LT again unless you are on the bottle..

hrcslam

Damnit. I knew it. Thanks guys.

What should I be shooting for on AFR with my set up then? My Coolant temps are steady at about 195°F in stop and go traffic with 115°+IAT.

I pulled a couple spark plugs and they indicate cold and rich. So I need hotter plugs and to lean out a bit. I can't even read the plugs for timing correctly because there's too much soot. I'll get a picture of one posted....

bowtienut, yes, my Dyno Tuner did. He's an Import guy. I think I need to convince him to just let me use the equipment. I installed the cam straight up, but it's got +6° ground in.

moehorsepower, interesting you say that. I know nothing on how to do n2o but will probably end with some in a year or two. Thanks for the info.

nitrous2fast

iTrader: (2)

Most n/a LT1 car's will make best power at 12.7-13.1 AFR.

nitrous2fast

iTrader: (2)

What plugs are you running?

hrcslam

Autolite 103.

I just adjusted my Tune for WOT at 12.67 from Idle to 2K at WOT, then 12.8 from 2000 to 4400, then 12.97 from 4400 to 5200, then 13.02 from 5200 to redline (6500). This was done with the AFR Correction @ WOT tables (Coolant and RPM) and assuming my 128 BLM is 14.7:1.

Does this sound good for AFR?

I gotta get some data logs in and adjust my timing. I'll be taking to the track on Friday (hopefully), I'll get some tuning done then.

Also, I did change the timing since my Dyno tune, I added 0.5° advance to what he had at WOT. Ugh.

moehorsepower

iTrader: (3)

Dont go by numbers too much, give it what the motor wants / likes, but of course check as you go, On LT's they like A/F in the 13's, 13.1 - 13.3, but check your plugs as you tune..

MEAN LT1

iTrader: (2)

Everybody has their own way of tuning and prefers to do things different. I know many people, my self included that have tuned MAF cars without touching the VE tables.

hrcslam

Yeah, I'm starting to feel comfortable tuning so I've been doing a lot of it by feel and sound.

The car sounds really healthy. I did a data log on the way to work and it did feel slightly better. At work I added 1° to 80kPa+ over 2800rpms. It really liked that. Random knock counts are pretty much gone now. And it pulls much harder than it did before. But the data log showed no difference in spark advance. Weird...

Yeah, I think that is how it's supposed to be done as in MAF mode it's using primarily the MAF for fueling.

My tuner didn't touch my MAF tables and only tuned my VE tables and AFR Correction tables and Spark tables. All with the MAF hooked up. My car, since fixing his tune, is very daily drivable on a cam that should be running at least 3.73, but I'm on 3.42's and cruising down the highway at 1450rpms with zero bucking.

I may add another degree, but will wait until Friday at the drag strip. DA's are getting worse (over 6600 yesterday), but hoping to up my trap from my last outing a month ago (5600DA). High hopes I know...

PA94Z

iTrader: (1)

I found my car liked 12.8 AFR and 36* timing total after the PCM added (commanding 32*). I tuned my car at the track. AFR was measured on a wide band.

I have a wide band for sale if you're interested.. The Holley ECU runs dual wide bands all the time so no need for the additional one anymore. It is a NGK AFX with NTK sensor:
PM if interested...

hrcslam

Thanks for the info! And the Wide band offer, but money is now too tight. Maybe in a few months after I get settled into my new job I can afford one.