Why does my van like soo much timing????

[turbovanman²]

Went out last night with a conservative tune, NO POWER, as I gave it more timing, it picked up. I see some of the maps you guys run and I am like WTF? My setup isn't anymore radical than alot of you guys-stock head, stage 1 cams, custom intake, ported exhaust manifold, 4" intake, exhaust cut-out?

This is really pissing me off, :censored: :banghead:

Full story here, not retyping it again-

http://www.turbo-mopar.com/forums/showthread.php?16425-My-Van-s-2.5-TIII-project-log&p=941242&viewfull=1#post941242

[Jabbott126]

maybe your base timing is off? Have you checked the distributor with a timing light?

[turbovanman²]

Yes, CTS disconnected, 12 deg initial.

[turbovanman²]

Ok, here are some pics of my timing tables, for comparison, Rob's Stage IV cals are the lighter dotted blue colour lines.

http://i12.photobucket.com/albums/a228/turbovanman/Burner%20chip%20computer%20info%20etc/Advancefullthrottle.jpg

http://i12.photobucket.com/albums/a228/turbovanman/Burner%20chip%20computer%20info%20etc/Advancepartlthrottle.jpg


My old 12 sec cal vs my new cal, had to use C14 with the 12 sec cal. 12 sec cal is the black line.

http://i12.photobucket.com/albums/a228/turbovanman/Burner%20chip%20computer%20info%20etc/AdvancefullthrottleDcal.jpg

[speedfreek500]

It likes more timing in the lower rpms or higher? Maybe your cal does not have an wild timing curve,I seen you said you made the octane alittle higher. Does it like more timing with just strait pump gas?

[turbovanman²]

It loves race gas and tons of timing everywhere, I can't run alot of timing otherwise it knocks with pump gas.

[ShadowFromHell]

Whats your compression ratio? Lower then normal? My Shadow LOVED timing with its 88T2 bottom and g-head. This was back before cheap cals and cheap scanners so I wasnt monitoring knock and was just adding base timing but the power difference between 14 degrees and 16 was huge. Doubt this helps but thought Id chime in lol.

[tryingbe]

What's wrong with your engine liking timing?

[cordes]

What is your total timing? Those two tables mean nothing without the advance from RPM, rpm limit, and the multiplier too.

[speedfreek500]

It loves race gas and tons of timing everywhere, I can't run alot of timing otherwise it knocks with pump gas.

I think you just answer'd your question there.

[turbovanman²]

Whats your compression ratio? Lower then normal? My Shadow LOVED timing with its 88T2 bottom and g-head. This was back before cheap cals and cheap scanners so I wasnt monitoring knock and was just adding base timing but the power difference between 14 degrees and 16 was huge. Doubt this helps but thought Id chime in lol.

G-heads love timing due to the lower compression and crappy chamber design.

My cranking compression is 120 psi.


What's wrong with your engine liking timing?

Just don't like to run alot, shouldn't have too.


What is your total timing? Those two tables mean nothing without the advance from RPM, rpm limit, and the multiplier too.

Not sure, I'll grab the other tables but their stock, don't touch those.


I think you just answer'd your question there.

Shouldn't have to run race gas to go fast.

[BadAssPerformance]

Just don't like to run alot, shouldn't have too.

Yeah, then maybe its a patch for something else not working right...

I run very little timing (under boost), even with 110, but then again base compression is a bit higher than 120. Maybe Cam timing would be a safer knob to turn?

[Directconnection]

This isn't the "stock head" that you ripped out all of the quench was it? I'd also suspect the cams....

[cordes]

Some of the stock cals have different advance from RPM tables. That makes the WOT and part tables look a lot different from one another with the same total timing.

[Turbo3Iroc]

You don't know your compression ratio? 120 on a compression tester seems low for a fresh motor. ~150 is what a healthy TIII cranks at. You might be making up that compression with timing.

---------- Post added at 11:49 AM ---------- Previous post was at 11:48 AM ----------

How much timing are you running in high boost?

[turbovanman²]

Maybe Cam timing would be a safer knob to turn?

Did you just say that? :faint:


Some of the stock cals have different advance from RPM tables. That makes the WOT and part tables look a lot different from one another with the same total timing.

Ok, I'll snap some screen shots.


You don't know your compression ratio? 120 on a compression tester seems low for a fresh motor. ~150 is what a healthy TIII cranks at. You might be making up that compression with timing.

---------- Post added at 11:49 AM ---------- Previous post was at 11:48 AM ----------

How much timing are you running in high boost?

I wanted it low, so I wouldn't need to run race gas etc around 20-25 psi. Its not a fresh motor, just a new head.

The timing maps are what I was running, tweaked it some more last night and much better, consistant low 14's.

---------- Post added at 11:12 AM ---------- Previous post was at 11:11 AM ----------


This isn't the "stock head" that you ripped out all of the quench was it? I'd also suspect the cams....

That head came off years ago, right now, a bone stock head with a valve job and back cut valves. Every cam I've run wanted timing.

[Turbo3Iroc]

I wouldn't call 14 high in high boost, especially considering your compression ratio.

[roachjuice]

Crank the timing.

[zin]

Weird sh!t happens, in the end you give the engine what it tells you it wants, don't try to make it fit a preconceived idea of what it should be.

That said, you're smart to be vigilant, and not advance blindly...

Best timing is a function of cylinder pressure, more exactly the point at which peak pressure occurs, which should be 15-20* ATDC. Normally (4" bore) that's a 34-38* BTDC ignition point. That is lighting the mix at roughly 36* BTDC will get you peak pressure in the "sweet spot" of 15-20*ATDC. Poor combustion and/or obstructions to the flame front can and often will "slow down" the flame front, for example, by having to go around stuff in the chamber (piston crowns, etc).

Smaller bores and "tighter"/more efficient chambers will speed up the burn which will require less timing to get peak pressure in the "sweet spot". Some Cosworth 4cyls only need a total of 24*!

If I had to guess, I'd say either poor combustion, OR you don't have as much timing as you think you do... It would be nice to confirm total timing on a dyno with a light to be sure you are getting what the computer says you are...

Unfortunately, you need to know your Brake Specific Fuel Consumption (BSFC) in order to know if it is poor combustion.

I'd also add my +1 to audibly detecting actual detonation. To that end I'd suggest doing this:
http://mdmustangs.com/David_Simmons_Cobra/detdtctn.html

In the end, if you aren't getting detonation, and your a/f is in the right ballpark, just give the engine what it wants!

Mike

[turbovanman²]

Yeah, I guess, lol, just tired of blowing shitt up.

[zin]

You haven't been melting or detonating pistons have you? I thought it was all ancillary stuff... But then I don't catalog this kind of stuff very closely...

Mike

[turbovanman²]

All I do is melt pistons from detonation or lean, most my fault, lol.

I guess just trying to understand the timing situation also, instead of just doing it but I'll just keep giving it what it likes and listen/watch for knock.

[22shelby]

advance till the motor sees god then back off a bit