Whats a safe amount of timing to be running on pump gas?

[1NaudiA4]

So my motor is out of my again. This time getting some rebuild love. Lower compression Mahle 8.5:1 pistons, Rosten main bearing girdle, new bearings,... just all the basic stuff since it just had a rebuild less than 500 miles ago.

I was quickly losing compression in cylinder 4 and I'm sure that the rest of my cylinders would have followed suit if I didn't stop driving. Turns out that I had some severe detonation going on the eventually caused the piston rings to lose tension. what it looks like to me at least... see for yourself in the pictures of the pistons. The air fuel ratio was steady around 11.5 at red line so it wasn't running lean.

Basic set-up: 98 A4 1.8t AEB

034 IIC
Siemens 870cc injectors
Aeromotive FPR
Ross Machine Fuel rail
034 Tubular Manifold
034 Down-pipe
Precision 600hp FMIC with 2.5" piping
Forced performance HTA3076 .82ar
3" stainless exhaust
Mahle8.5:1 pistons 81.5mm
Scat Rods
Rosten Main bearing girdle
Synapse Waste-gate
Synapse BOV

I know it says demo mode but I just unplugged my computer to I could hook it up to the internet.

[bassed]

Depends on the motor and how much timing it can eat before you have knock or pull timing. Do you run w/m?

[mike-2ptzero]

if you put the info into a spread sheet(2D map) it will be much easier to look at.


404 -16 -8 -1 4 6 9 12 14 16
354 -16 -8 -1 4 6 9 12 14 16
305 -10 -2 5 10 12 15 18 20 22
256 - 8 0 7 12 14 17 20 22 24
207 - 2 6 13 18 20 23 26 28 30
157 5 13 20 25 27 30 33 35 37
108 10 18 25 29 32 35 38 40 42
59 14 22 29 34 36 39 42 44 46
10 18 26 33 38 40 43 46 48 50
0 8 15 20 22 25 28 30 32
0 1k 2k 3k 4k 5k 6k 7k 8k

[andyrew]

Holy crap man! Your not running w/m?

That really sucks that this happened...

[1NaudiA4]

No I wasn't running w/m. I didn't even really look at the timing map because I thought it was set up conservatively and I didn't feel and knock/detonation but I guess you can't always feel it.

I was think of pulling back the main rpm timing map for break in by about 8 degrees. Then once its all broken in I'll hop on a dyno.

Mike: So should I just plug everything into excel and make a graph?

[Poopie]

definitely looks like it got too hot. I hit 29* of timing request with about 5* of timing pull on straight pump gas...this was peak and it tapered down. It all depends on the tune and the efficiency of the cooling.

[mike-2ptzero]

No I wasn't running w/m. I didn't even really look at the timing map because I thought it was set up conservatively and I didn't feel and knock/detonation but I guess you can't always feel it.

I was think of pulling back the main rpm timing map for break in by about 8 degrees. Then once its all broken in I'll hop on a dyno.

Mike: So should I just plug everything into excel and make a graph?

Well just plug the numbers I posted into excel. You dont need to make a graph because you want to look at it in 2D. Then kind of figure out your boost/rpm thru the blocks.

The map might be a little high for 93 octane only. At 256kpa(22-23) and 4k rpm your hitting 14 degs of timing.


You might want to look into putting a EGT probe on your #4 cylinder if you dont already have one on the manifold. The ring most likely lost tension because of high EGT's. You might also want to start doing some logs of the IIC when you have the car running again.

[Don Supreme]

[QUOTE=mike-2ptzero;2854709]


You might want to look into putting a EGT probe on your #4 cylinder if you dont already have one on the manifold. QUOTE]

Why #4?

[A4ringedONE8T]

You might want to look into putting a EGT probe on your #4 cylinder if you dont already have one on the manifold.

Why #4?

Runs the hottest and leanest

[mike-2ptzero]

[QUOTE=Don Supreme;2854794]

You might want to look into putting a EGT probe on your #4 cylinder if you dont already have one on the manifold. QUOTE]

Why #4?

Well for him it seems #4 runs the hottest. I think other people have had issues with cylinder #4 before any of the others.

[Don Supreme]

#3 here.

[1NaudiA4]

Do you think drilling into the #4 runner would cause any weakness issues that could eventually lead to cracking?

[Don Supreme]

Do you think drilling into the #4 runner would cause any weakness issues that could eventually lead to cracking?

I have the same fear, but my mani is pretty damn thick, so I hope it works out.

[mike-2ptzero]

Do you think drilling into the #4 runner would cause any weakness issues that could eventually lead to cracking?

No it shouldn't. If you are running a thin manifold you have more things to worry about then putting a EGT bung on it.

[1NaudiA4]

034's manifold is pretty thick so I shouldn't have any issues then. Its going to be a bitch to drill through it though.

[mike-2ptzero]

034's manifold is pretty thick so I shouldn't have any issues then. Its going to be a bitch to drill through it though.

You will not have a problem drilling a whole thru it. I have mine located in the FR manifold and they use a much thicker tube to make their manifold.