Ignition advance, Dyno and Detonation

[apardal]

Hi!!

Same subject, different topic...

I would like to have some educated help about what's going on with my project.

Here are the specs (some of may already know them):

-Blue Top 4A-GE
-Castrol RS Formula 10W60 fully synth engine oil
-Wiseco Pistons 81.5mm
-ARP conrod and crankshaft bolts
-Toda Flywheel 3.7Kg
-Toda Camshafts 288/288 7.9mm lift
-Slightly ported and polished head
-Bronze valve guides
-3 angle valve job
-Shaved head 0.6mm block 0.1mm
-TRD 0.8mm Head gasket
-Compression Ratio estimated @ 12:1 - 12.2:1
-NGK Spark Plugs BCPR6ES-11
-Stock intake manifold W/O T-VIS
-300cc's injectors
-Tsudo Exhaust headers with 2.25" pipe with mid muffler and final muffler (Apexi WS Universal)
-Megasquirt V2.2

I went to the dyno last saturday, trying to figure out what was the power output...

- first test, setup made days before so that I wouldn't hear my home made engine stethoscope pinging... with ignition timing very low.

23º ignition timing above 5000rpm

120.4hp@7800rpm e 117.9Nm@5259rpm



- second test, tuned the mixture and lowered the ignition timing. Thought it could be detonation holding the power down!

20º ignition timing above 5000rpm

116.0hp@7888rpm e 124Nm@4562rpm



At this point we decided we should advance the ignition timing since from the moment it detonates, the engine will loose power

- third test, with data logging always on, another tune was made to the VE map.

26º ignition timing above 5000rpm

135.9hp@7896rpm e 128.7Nm@5123rpm



15 hp gain with 3º advance... time to go further

- forth test, removed the air filter

30º ignition timing above 5000rpm

163.4hp@7588rpm e 155.3Nm@7061rpm



We were impressed, 7º of ignition advance gave 43hp with a setup that
initially looked like it didn't work.

I could have tried another test with 2 or 3 degrees of advance but I went to the dyno to make just one or two tests and I was already way off my budget!

I think the torque curve is alright, because it's good through 4500rpm until 7000rpm but the value could be a little higher, maybe with a little more ignition advance it will be better. I draw the conclusion that I've no need to have the rev limit at 8700 since my max power output is around 7500rpm.

At the moment, I'm trying to figure out what's the thing with the noises from my home made engine stethoscope because what I thought was detonation, can't be, because it will make strange noises with 23º of ignition timing and with 30 it makes a little more noise, but gains 43hp. If it was detonation, there would be no power gain, I think.

On the road we tried to figure out what detonation would be and raised the ignition timing to 40-45 degrees and the noise becomes more intensive, for sure, but it is difficult to understand at what point detonation starts.

Right now I need to decide whether I'm going to install ITB's or not, if I'll change my cams to a more aggressive setup or if I'll leave it be and try new colder spark plugs (BCPR9ES-11). Either way, I'll need better oil cooling devices...

A video made today driving around the new setup!

http://www.youtube.com/watch?v=xHcqzyXyAIs


Well, what I would like to know from you guys is what do you think about the "supposed to be" detonation issue, because raising the ignition advance will make a lot more power and a little more intensive noise from the engine that I hear even without the DIY sthetoscope.

Right now I have ignition timing at 27º with a little less power than 30º, of course, and I'll still have engine noises when pulling hard uphill in 4th or 5th gear, around 5000-6000rpm, and this noise will be subtly and randomly heard until 8000-8500 rpm.

Best regards

[Lipinhu]

Quote:If it was detonation, there would be no power gain, I think.

Yes, most cases, the engine starts to loose power even before it detonates.

Bit offtopic, but what is your idle rpm?

[apardal]

1100-1200rpm. It would idle better with ITB's.

[cavey]

just something totally wild: maybe the stethoscope is being used in the wrong way/the resulting sound is interpreted in the wrong way?

I'm no mechanic, but I just did a simple google on "engine stethoscope". This seems to be an interesting page:
http://remanufactured-engines.com/page4.htm

good luck with finding the cause'n'solution!

[apardal]

That is possible, since the gain of power contradicts the detonation issue...

Thank you for your time cavey!!

[byd1380]

I have astandard 4AGE large port with ITB's fitted, i run up to 38 degress advance at full throttle load and high rpm, if you pm me your email I can send you a screen dump of the map.

Ivan

[apardal]

Ok Ivan, thank you for you help, but my problem might be having too much compression!

I have to order ITB's soon anyways... and it will help a lot, I think.

Best regards

[Rasteirinho]

I think you can solve you problem with more air or less compression...

[apardal]

I think more air will be the solution

[KrizKH]

Rasteirinho Wrote:I think you can solve you problem with more air or less compression...

I'm not sure what you mean but I don't see how "more air" can solve problems with detonation?

I've experienced that the last few degrees give good effect and as we start hearing detonation the hp stops increasing.
Think we ended up with 33-34 degree advance.