How much timing advance is safe?

[quato]

Hey folks, I have been going through the break-in of my new engine and also doing a bit of tuning as well. I used the maps from my 2.0 engine but now that I'm 2.4 I'm hitting completely different cells as could be expected. Since the engine is brand new, I'm worried about hurting the engine by going too far.

A brief history of the car. When I bought it, it ran flawlessly and was able to run about 20-22 degrees of peak timing advance. Then it eventually developed a miss like there was a boost leak somewhere. I did a boost leak test and had air coming out of the crankcase, so no bueno but ok since I know it was an untouched engine before and may or may not have had some hard miles. Now the engine is rebuilt with a G64B bottom end (I'll list pertinent details below), pretty much fully built and it's loving any timing I can throw at it. I'm running about 12.5-13.5psi and about 20degrees of advance with not a hint of knock anywhere.

I do know that it's possible to advance too much and possibly hurt the engine (usually with E85 or race gas) but I want to stay within a safe limit. I don't have access to a dyno so I am doing this slowly back and forth to work datalogging and reviewing and tuning, rinse and repeat. After everything is fully broken in, I'll go on up to ~22psi and retune from there.

Ok now my specifics:

G64B Block .020 over
No balance shafts
Kiggly girdle (overkill for my application but hey, I already had the engine open...why not haha)
Manley H-Beam rods
Manley 8.5:1 pistons
ARP hardware throughout
New head
HKS 272's in/exh
New valves
Supertech springs
Fel-Pro Permatorque head gasket
Fidanza flywheel
Southbend "stage 3" clutch

Things I forgot to include when I first posted:
Aeromotive A1000 external pump
Braided line to Aeromotive FPR and back to fuel cell (came with car)
FIC 1050 injectors
Evo8 ECU
Evo8 MAF
Apexi solenoid for electronic boost control
Evo8 3bar MAP
3" exhaust
Tial 38mm wastegate
3" deep spearco intercooler with 2.5" piping
LC-1 wideband
running 93 octane for now but will tune to e85 to use with map switching

Thanks for any input or advice /ubbthreads/images/graemlins/worthy.gif

 

[prove_it]

What turbo, exhaust, and IC?

It matters. Truth is all engines are different. Yours may like more, or could like less. Best thing you can do is run around 12 degrees up to peak torque(no more than 14) then step up to about 17-18 at redline. You didn't mention fuel, so I'm assuming your using 93 octane. My E85 tune runs up to 22degrees and it's great. It's too hard to tell when you'll pop the engine though. You could be adding only 5whp by going to 18 versus 16 degrees. In that case it's not worth it. That's why you really need a dyno to tell where to stop. I would say that with a low boost(15-16psi) on 93, 18 degrees should be ok, but diffently no more. Also higher boost means less you can get away with.

 

[quato]

Oops sorry about that, I knew I was forgetting something. I'm running a Turbonetics 60-1, but I don't know the a/r as it's not marked anywhere on the turbo. Exhaust is 3" basically turbo-back. It really goes from about 2" right at the turbo and expands to 3" after the oil pan. Intercooler is a 3" deep spearco (don't remember all the measurements but it almost fills the bumper opening) with 2.5" piping.

Also I'm tuning with an Evo8 ECU and an Innovate LC1 for a wideband. I have a JDM Evo8 3bar map sensor and a gm air temp sensor. One day I'll go speed density when I get a good solid tune under my belt.

Actually I'll update my first post for readability.

What you said made some sense. Basically because I'm running such low boost right now, I can get away with this timing. Then when I up the boost, I'm going to have to keep the timing a bit lower. Yes I'm running pump 93 right now but I have map switching on my ecu and would like to be able to switch between e85 and 93 as I need to.

One thing that I've seen so far is that when I started messing around with the tune I was at ~26 lb/min and now just from adding timing I'm up to 33 lb/min at about 13psi. That's just going off of what the MAF is telling me. So it looks like I'm going the right direction, but I want to keep it safe.

Ideally I'm shooting for a good safe tune at 22psi (when the clutch is broken in) then I'll bump it up to almost 30 on e85. Going to have to upgrade my MAP sensor though...

 

[quato]

Another thing. I have verified that my knock sensor does work. It still has the annoying part throttle knock that it had when I was on the stock 2 liter engine, haha

 

[cheekychimp]

Did you have any machine work done to the block when you put that girdle on?

 

[quato]

I did. The block was tanked, decked, bored, cylinders honed, mains were align honed. The entire rotating assembly was balanced and all bearings were checked for clearance by the machine shop.

 

[cheekychimp]

Before or After you added the girdle?

 

[quato]

Before anything, I made clearance in the block to accept the girdle by grinding down the ears until the girdle fit without catching anything plus a mm or two of space. Then with the girdle attached and torqued with the ARP mains it was align honed and then checked.

 

[diambo4life]

Look at your spark plugs. You will know whether your timing is too little, too much or you are at the verge of blowing your sh!t up. /ubbthreads/images/graemlins/wink.gif

 

[cheekychimp]

Quoting quato:
Before anything, I made clearance in the block to accept the girdle by grinding down the ears until the girdle fit without catching anything plus a mm or two of space. Then with the girdle attached and torqued with the ARP mains it was align honed and then checked.



/ubbthreads/images/graemlins/cool.gif Good!

I made the mistake of buying my girdle after the engine was done and not wanting to pull anything apart I haven't been able to use it. Waiting for something to blow so I can utilize it on the next build.

 

[Brianawd]

Only way to really know if your at MBT is to put the car on the Dyno and go to town tuning it. Every car will be different. On my galant MBT at peak torque was around 17degs and peak hp was around 23degs.

 

[beaner]

Quoting quato:
I'm running a Turbonetics 60-1


My 60-1 didn't wake up until about 30psi. On 93, at peak tq my timing would be near zero, ramping up to about 12 at redline. E85 is whole other ball of wax, I wish I had switched over and ran more psi before swapping it out. Ah well.