Aggresive Timing GTP

[Lumpo]

Lets see some of your guys timing tables for your 97-03 GTP. Looking for some aggressive cruise and part throttle timing. Just want to compare to mine.

[supersle]

I used the timing tables from an 04+ which is a lot more aggressive. I've been getting better MPG with that in cruise. Don't have it handy right now to post though.

[passingpower]

This is my Hi Oct table. I use this in conjunction with pseudo lean cruise and it doesn't knock. Which means I can push higher. (limited by MaxBreakTorque and knock of course).

I plan on tweaking this up when it gets hot (for Michigan) this summer.

Edit: This is on an 01 GTP.

[Lumpo]

Ours are actually pretty close. Check mine out...

[GeoJB]

Don't know if having 0 kr at lower RPM's is a good idea. You never know while your low speed cruzing. could be just a "tad" too much timing.......then POP!

[xpzd3800]

what are you guys seeing for gas mileage, I might be changing my table up soon..

[passingpower]

Zero knock is always a good idea.



During cruise, a 'tad' would mean you're on the back side of the peak torque for that RPM. Hence my referral to the MBT limit. At the low throttle angle and high(er) plenum vacuum at cruise, cylinder fill is so low especially with an 8.5:1 ratio engine, It's difficult to achieve a peak cylinder pressure high enough to blow a head gasket. I'm not saying no one has done it at cruise, I'm just sayin' you almost have to make it a goal to see it POP during cruise. In fact, at 8.5:1, the L67 should have had a higher timing table in cruise from the factory. Instead, we have the same tables as the 9.4:1 L36. Guess fuel economy wasn't high on GM's list in 2001. Psst! cheap tweaking of firmware on old hardware is how the recent "gains" in mileage have been attained. The L67's low compression pretty much demands aggressive timing to offset the inefficient burn during cruise.

Between PLC and this table, I have no trouble seeing 38mpg at 60mph and that's withstanding the ~5% economy hit burning E10.

Call BS all you want.
I was asked for my two cents.

[passingpower]

Almost forgot to mention:
Any reference I make, made or will make to PLC, pseudo lean cruise, or lean cruise, is in regard to off-road use only.
And I would never endorse its use by anyone in the U.S.A.

[Lumpo]

Anyone else have a timing table to share? I would really like what the rest of you guys have your timing set.

[BlackGS]

This is running E85, and is actual timing from a scan. I think boost was around 18psi on the upper limits.

[GeoJB]

Don't know if having 0 kr at lower RPM's is a good idea. You never know while your low speed cruzing. could be just a "tad" too much timing.......then POP!

Ah Dam, should have been clearer..... not enough coffee this AM.
In your tune, under Spark retard: Knock fast attack rate Vs. RPM - set to zero @ 400 800 1200 RPM and 1 @ 1600 RPM.

Passingpower, you bring up a good point.

[murphinator]

like black gs this is a screen shot. Its from a scan about 2 years ago.at the time I was commuting to a job 2 states away daily 6 days a week and spent a lot of time working on cruise timing - not saying there was a lot of science or understanding behind it but hundreds of flashes later the cells i was in around 72-74 mph had all the timing they could take without kr on a 3.5pulley/plog/3" dp / supporting mods car that would average 31-32 mpg (480-500 miles out of a tank) and stop at the track on the way home occasionally and run 13.5 @104

[Lumpo]

Wow so it looks like i should be able to add quite a bit more timing. Im just worried about adding too much timing. I know you can add too much timing and be KR free. Is 50* still a safe amount to run at cruise?

[passingpower]

iirc, 50° adv is a firm-coded limit within our OS that can't be changed without TT.

That's a fine piece of work, Murph. I plan on referring to that this summer. TYVM
Now, the only thing I need is hours of free to dirt-cheap dyno time. Yeah right!

I'd be surprised if 50 was not safe from a detonation or pre-ign standpoint. As to whether it makes more useable torque or just serves to fight the piston on the compression stroke, well...

[Lumpo]

Is this the fuel pump i need to convert to E85?

http://cgi.ebay.com/ebaymotors/High-...Q5fAccessories

[murphinator]

iirc, 50° adv is a firm-coded limit within our OS that can't be changed without TT.

That's a fine piece of work, Murph. I plan on referring to that this summer. TYVM
Now, the only thing I need is hours of free to dirt-cheap dyno time. Yeah right!

I'd be surprised if 50 was not safe from a detonation or pre-ign standpoint. As to whether it makes more useable torque or just serves to fight the piston on the compression stroke, well...

car is still running that cruise timing with 215,000 miles with no mech. issues , effort to climb slight grades was noticeably less as the timing got up into the 40's is 50 better ? I dont know either lol but it takes it just fine

[Rebel_Kings]

Ours are actually pretty close. Check mine out...

i notice your sc and running 14.7:1

honestly it may seem weird but try running 13:1 or 13.7:1 and check out your performance and mpg. in sc cobalts were running 13:1 and were getting 40 mpg on freeway at 75mph.

[murphinator]

i notice your sc and running 14.7:1

honestly it may seem weird but try running 13:1 or 13.7:1 and check out your performance and mpg. in sc cobalts were running 13:1 and were getting 40 mpg on freeway at 75mph.

in closed loop narrowbands and trims should bring you back to lambda 1 or stoich for the fuel you are running is my understanding

[Rebel_Kings]

sorry overlooked the tune and we have it set at 14:1

what happens from what i understand is when you set the ratio thats what everything goes by. because fuel trims just add or minus fuel in certain ares of your driving based off of your cars history of you driving it. you re set the ltft's after you change some things with the fuel so your car has to relearn them.

then what most people do is they unplug there MAF copy there high octane table over to the low, drive about 50 miles of everyday driving never going to WOT and just data log to get yourself a nice histogram telling you where fuel was added and where it was taken away, that way you can go back through your tables + or - wherever its needed. (out of memory so some things might be a little skewed sorry.

[Rebel_Kings]

in closed loop narrowbands and trims should bring you back to lambda 1 or stoich for the fuel you are running is my understanding

http://www.hptuners.com/forum/showpo...64&postcount=1
pretty much same idea excepy at 14.0 not 14.7