Ok to make this long story short, went to the dyno with my AEM EMS and GT35R equipped EVO to see how big an effect timing changes would have on my car. Boost was set @ 28psi with an a/f ratio of 11.5-11.3 on VP C-16. I set timing from 5500 rpm's and up at all boost levels above 23 psi to avoid getting variations if boost were to fluctuate. All runs were done to 7000rpm except for the first one which was only taken to 6500.

These are the results in order

1. 6.20 degrees of timing = 410 hp
2. 8.31 degrees of timing = 427 hp
3. 10.07 degrees of timing = 447 hp
4. 11.83 degrees of timing = 467 hp
5. 13.94 degrees of timing = 483 hp
6. 14.99 degrees of timing = 491 hp

I stopped @ 14.99 degrees because of time constraints.



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The hp would fall if I kept reving the engine since I was not advance timing. I've heard so many stories about timing being low at peak torque, that it shocked me that I could go this high with my timing numbers.

Last run of the night was 15 degrees @ 6000rpm climbing all the way up to 29 degrees @ 9k rpm's

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I never thought a single degree of timing can make that much of a difference.

 

Don't be shocked. Those stories are correct, but they do not apply to your setup as much as they do to engines with smaller turbos that generate peak cylinder pressure (peak torque) earlier in the rpm range. Smaller and larger turbo engines have very different timing requirements due to the difference in rpm, so it's like comparing apples to oranges.

An engine with a turbo that delivers 28 psi at 3500rpm will have different detonation threshold than the same engine, but with turbo that sees 28 psi at 5500rpm. Speaking in very general terms, the higher the manifold pressure and/or the lower the rpm, the lower the detonation threshold with respect to 'deg BTDC'.


Believe it. A few tenths of a point in AFR typically makes little difference. A degree or two in ignition timing can make a big difference. Tweaking the ignition map is generally where one spends the most time tuning.

 

That is kind a cool how for every two degrees, it jumps almost 20 HP..

 

I am not trying to be mean but i thought it was common knowledge that one degree of timing is roughly 10whp on a turbo car.

 

Adding timing is also the law of diminishing returns. This thread is a little misleading because the OP started with VERY conservative timing and added timing in until it was where it should be. Had he kept going above 14.99 degrees, you would quickly see the power increase fall.

 

Cool thread but +1 with slowrice, you started awefully low! Cool graph, but if I see another dynojet post with mph instead of RPM I'm gonna kick someone in the *****!

 

For C16 yes Keep this in mind if reading the thread. Good results though

To the original poster. Where is VM Dyno? I've only been to Sporty Dyno

 

Werd.

One particular car I tuned picked up 80 WHP at 7000 RPM (600-680 WHP) with 2 degrees of timing advance. The next 2 degrees did absolutely nothing. Pulled out a degree, nothing. Dropped it back to the 2 degrees advanced from the first pull and moved to the next boost level.

A/Fs can be the same way, that car for example going from10.5:1 to 11.0:1, picked up like 30 WHP. 11:1 to 12.5:1 picked up nothing. Set the car to like 11.5:1 and knew I was on the safe side but not giving up any power.

 

This dyno is in the town of Sabana Grande, GoFast Dyno is the name but since I have the software on my laptop it displays my initials

The rpm pickup missed every now and then and the reading sometimes would cut my rpm in half. Thus the reason for posting it in vehicle speed.

 

..............

 

So changing your Max Dwell values allowed you to push the stock coils with these results is just awesome.

 

Regardless of whether you started low or not, still cool to see the effects of timing (whether low or high). Nice job!

 

I don't think he was showing this as an example of bad tuning to good tuning.

i think he just wanted to show how timing affects power. to that end it doesn't matter where he started or where he ended.

it's a great way to show people how timing can affect power and most people that do tuning know that once you reach the point where adding timing does nothing, back off and look to tune elsewhere.

Thanks to the OP for showing the details

 

I'd like to see a proof done, in this fashion, of a tuner explaining why a fully built Evo with 35R should run 22 psi on pump gas

I mean is anyone left who still beleives 22 psi can be the right pump gas boost for your typical fully built 35R car? People run 22 psi on the stock turbo safely. And as Ted has described in this thread, your tolerance for ignition advance increases as peak torque / max boost occurs later. And also the more efficient compressor and larger hotside also contribute to higher ignition advance tolerance.

So someone explain to me why we still see fully built 35R cars only tuned for 22-23 psi on pump gas?