Dyno log and tune

[Slowrc]

Here is the scan and tune for my 98 Z28. tr230 cam ,home cleaned up heads,3200vig stall, pacesetters, 3"duals, slp lid, and stock 4l60e and 3.23 rear. Looks like I have some work to do!

[5.7ute]

Not too much work at first glance. Knock some timing & fuel out of it (Both commanded AFR & your airmass estimation model) Get your Bens within at least 2% then start throwing some timing back at it to find MBT.

[Slowrc]

Thanks,

Are you saying I am close enough to drop some fuel out of commanded pe and my ve tables and retest, or should I go through the auto ve process and disable the maf. I also logged a stumble from a red light that show 15.20 on the wideband and 14 KR this morning. I am guessing thats a lean spike.

thanks again!

[Slowrc]

http://i19.photobucket.com/albums/b184/Slowec/dyno.jpg


I guess I REALLY need a ls6 intake!!!!

[WeathermanShawn]

Not bad. Good work.

Yes, that LS6 Intake will help. I read a post on another site (:grin:) about the LS6 intake does not like spark advance over 25 degrees. Thats not a bad thing, just something to consider. It might help solve your slight KR situation too (lower spark advance at WOT).

If you are staying MAF, you can work on it to affect fueling. But it never hurts to have a solid VE Table, especially if you can do it on the dyno.

Congrats on your build and dyno results.

[joecar]

I think you can benefit from doing AutoVE... do timing as 5.7ute said above.

[ScarabEpic22]

Yes, wow 12.227 commanded AFR and 10.92 actual! 10.92 is waaay rich for a N/A motor, should be about 12-12.8 depending on what you want to shoot for.

Good thing is you already have the wideband, so AutoVE'ing will be easy! (Or try WeatherManShawn's new method...)

[5.7ute]

Thanks,

Are you saying I am close enough to drop some fuel out of commanded pe and my ve tables and retest, or should I go through the auto ve process and disable the maf. I also logged a stumble from a red light that show 15.20 on the wideband and 14 KR this morning. I am guessing thats a lean spike.

thanks again!

When getting a baseline to start on the dyno, I command around 12.5 AFR at WOT with no more than 25 degrees timing. Then set timing a bit lower around 3-5000 rpm.(Near estimated peak torque)
Do a couple of pulls adjusting the VE table (or maf if still enabled)to get commanded AFR & actual AFR to match. Then slowly add timing until either torque shows no increase, or you get knock. (If you get knock pull a few degrees from these points)
Then you can start leaning out PE some more & see if torque again starts to increase(Timing may take a bit more tweaking at this point). Where knock was evident earlier you can try enrichen some to see if this will give a bit more resistance to knock.
Going in this manner should keep you safe from engine damage.

[Slowrc]

Thanks guys. I logged some on the street and found My 12.2 commanded shows up at 12.48 on the street. I never run 3rd gear out like I did on the dyno. 140mph !!! twice the speed limit ya know. Why would second gear be so close and third richen up so much???

Thanks again for all the help!

[WeathermanShawn]

Mmm. I had that problem before...

Something about load. and your RPM and MAP VE Values are obviously different in 2nd or even 3rd vs 4th gear, as are your MAF values (if MAF-Enabled).

You have to hit every cell (and MAF value) in every gear to get it right. I know its a hassle, but different gears will show different loads and varying MAP and RPM's. Welcome to tuning..:).

Keep at it though. You will be happy with the end result!

[Slowrc]

When I went to autove my car was running at 10.9 to 1 afr. Guess thats why I could command higher afr in pe and open loop and it still ran 10.9. I would have thought it would not be using the ve table at that point , but obviously I was wrong. I have been running in tune mode(no maf) for days now and everything is much better as far as commanded vs. actual. Dialing in the ve is fun:cucumber: once everything is set up.

[TFZ_Z06]

Thanks guys. I logged some on the street and found My 12.2 commanded shows up at 12.48 on the street. I never run 3rd gear out like I did on the dyno. 140mph !!! twice the speed limit ya know. Why would second gear be so close and third richen up so much???

Thanks again for all the help!

If you look closely, your o2 sensor is reporting a good value for power production, that is until 5347rpm. At that point, you start losing intake vacuum, have a small hit of knock retard, and your VE table is too rich in that area. You go from 98% in the VE table to 101%. Of course a commanded 12.23 vs 12.48 is pretty close.

Instead of tuning for AFR sometimes, I watch vacuum. If an engine is pulling vacuum at WOT, its better than having one in a state of reversion. I don't think your cam is big enough to cause that problem, got to be in the A/F.

Consider removing about 0.5 degree spark after (5200rpm,0.80gm/cyl)
and reducing VE around 5200rpm, ~1-2%.

[Slowrc]

you are right, I have been leaning it out via the auto ve process. and I am going to reduce mytiming and slowly add it until knock reappears, then back it down some.

thanks for your comments.

[Slowrc]

Anybody want to take a stab at how much getting my afr from 10.9 to 12.8 would help me on the dyno?

[joecar]

I take a wild stab at it:

I'm guessing you would gain 10-15 hp at peak...

If your VE was corrected I think your torque curve might be cured of the step down at 5000 rpm which would also fix the dip in the hp curve at that point...

If you could get more air (you mentioned going to an LS6 manifold) and adjust timing for this, it would probably make the torque curve wider (which would take advantage of your stall converter) and maybe the power curve would stay up after its peak...

$0.02 worth of bench-racing... :)

What heads (how much can you flow) and valvetrain (how high can you spin) do you have...?

[Slowrc]

Heads are 806 castings (yeah I know:doh2:) home cleaned, polished, and lapped and recut stock valves.(3 angle and hand lapped) hardened pushrods, 918 springs , and tr230 cam. bottom end was rebuilt with speed pro rings, durabond cam bearings, clevlite passenger rod and mains, stock polished crank and stock rods with arp bolts. I spun it to 6700 on the dyno the other day, and it didn't seem to mind.

I will have the ls6 intake by Sunday. I had not tuned the VE before the dyno. The commanded and actual are spot on now thanks to You and some others on hear helping me get through it! (BIG thanks to Joecar and Mr. Prick for always helping me through!!!)

[Doc]

Rodney,bring her back to the shop and let's find out!

[joecar]

Slowrc,

Thanks also goes to 5.7ute and TFZ_Z06 who had some good comments.

I thought this was a dyno only pull (i.e. no tuning)... hmmm... if this was already tuned then possibly some mechanical problem may have developed (because I know that Doc is meticulous).

[Doc]

Just a dyno day down at the shop for one of the local car clubs

[Slowrc]

It was untuned at the time of being dynoed(actually a mail order pig rich tune)"get what ya pay for". Neither Doc or myself had touched the VE. Now I have the ve dialed very close. :)

Doc, I was tryin to get the truck guys to set up a dyno day on april 3rd, but they are not coming thru with the numbers. I'll be back to you with a tune,
ls6 intake , and whatever else the tax refund will buy me and we'll see what she has in her.