[OpenFlash]

Hi guys,
A lot of talk about ignition advance and boost these days. And there is a good deal of misinformation spread about this forum. The idea behind engine tuning is, generally speaking, to make power the most efficient way possible given the constraints (octane, hardware, engine load etc,). And there is no bigger contributor to combustion efficiency as ignition advance. The less advance, the less mechanical leverage is applied to the top of the piston during the combustion process. Think of it as pushing a shopping kart when it's already at nearly a full arm's length away. Doesn't matter how much you push out those arms during the first 80% travel, you are only applying a small portion of that energy on making that kart move forward. You're arms are still working, you are still extending energy but your efforts aren't being put to efficient use.

Now get a little closer to that shopping kart and how your efforts are put to better use. As you can imagine there is an "ideal" distance between you and the shopping cart that will result in the best possible shopping kart acceleration given the equal pusher effort. Too close and you don't have good enough leverage. To far away (as in the first example) and you are just wasting most of your energy into the air. But there is a "sweet spot" in the middle that will result in best possible shopping kart performance. It is this distance you "tune" for.

In the case of engines, ignition timing defines this "distance". But since the engine rotations, this "distance" is actually described in degrees of rotation. That's where ignition advance degrees come from.

In the real world, there are many things that keep us from running our engines at the "ideal" ignition advance (Min advance for Best Torque, or MBT). One constraint is octane. The less you have, the more likely the air/fuel ratio charge will pre-ignite before the actual combustion/burn occurs. In the case of most turbo engines, running at MBT is only possible when using race gas and/or methanol injection. Another realworld limitation, that many people are seeing now with respect to n54 flashes, is boost control. With the MSD80/81, controlling boost with respect to intake air temp isn't straightforward. It requires fiddling with several maps, compensations, etc,. And still not getting it right. This is why you see stock cars with flashes running absurdly high boost pressures in hot ambient temps. When the engine is at these high loads during these adverse conditions, it cannot operate anywhere near MBT. Instead, it operates inefficiently with low/negative timing advance. The engine still still combusts a lot of air/fuel but only a small percentage of the combustion energy is used to push the piston downwards during the power stroke. Instead, most of the energy is wasted in the form of heat that ends up being absorbed by the cooling system and by the exhaust. End result is a lot of engine stress and not a lot of performance.

So where is MBT assuming no such constraints? As with any engine, it will vary from car to car slightly. Hardware upgrades that change the engines volumetric efficiency (turbos, exhaust, intercoolers, etc,.) will also have an effect on MBT.

Today we tested to see how much power we could make running ~15psi on our shop car. The car was running on 91oct pump gas with our PWM methanol system. The car has FBO with ASR turbos with a prototype upgraded fuel system (which does nothing at these power levels). The map is based off of the publicly available 7-11 map. But tweaked/user tuned for a higher Proportional gain (faster boost response) and an adjusted Wastegate DC table (no DC taper up top).

Running on meth, knock isn't an issue. And running with a Procede, boost control isn't a concern. So running a stable 15-15.5psi with 0% ignition correction (stock timing), we get this log:



Actual timing is what just about everyone is familiar with when it comes to a good, knock-free tune. Around 12 deg in the low end, ~10 deg in the midrange, tapering up to 13deg by redline.

Next, we adjusted timing to actually ADD advance when meth is flowing. When meth isn't flowing, a more conservative timing map is established. The new ignition control hardware in the Procede rev2.5/3 make this transitioning between negative and positive corrections possible. By adding just 2 deg of advance, we get the following datalog:



Now we are seeing up to 16 deg up top when running on methanol. As before, not a hint of knock.

On the dyno, the difference between stock timing and stock timing+2deg is pretty significant. As much as 25whp at 6100rpm!



And yes, that is nearly 470whp at just ~15psi. On a 90 deg day. Running 91oct+meth. With conservative on-boost AFR ranging from 12.5 to 11.8 across the board. And with peak power head right up to the rev limiter.

On the road, the engine sounds ferocious. And a lot happier than it would running another 1-2 psi of boost with less advance. And since the engine is running more efficiently, it is running at a lower BSFC (fuel consumption per hp) and with lower EGTs. The engine oil and coolant systems will also be less taxed.

Please note this this extra advance would not feasible if the car wasn't running the PWM meth system. No doubt that the DME would have retard the timing in response to knock activity. So how much power power will another 1-2 deg of timing add in? Or are we already at MBT now? At what point will the extra octane afforded by meth going to be insufficient? All these are good questions that will be fun to answer in the near future now that we have our engine control system and meth hardware working as we need it to.

Because today, we just picked up a free 20-25hp with no increase in boost pressure

Cheers
shiv

[335xiRT1]

looks good.
PWM meth system is needed for this extra power.
your old meth system wont be able to accomplish this???

[chris b.]

nice! good read!

[tofu-]

was excited until i realized these were aftermarket turbos

[dzenno]

Man that's so cool

[TommyLights]

Originally Posted by tofu-

was excited until i realized these were aftermarket turbos

+1, lol!

[RR80]

Thanks for the info~~ It made me want the 2.5 upgrade more and more... ...

[chingy24]

Shiv,

How much will this "extra advance" effect the guys without upgraded turbo's?

[lamia2super]

cant wait to install my turbos with the new actuators

[Ilma]

I couldn't agree more!

I have been experimenting with higher octane and lower boost to get maximum advance on my timing curve.

Car feels soooooo responsive and eager with lower boost/higher timing.

And it also sounds better and feels better.

I then tried higher boost and lowered timing advance by a degree more than the standard 7-11 timing map and the car felt flat and sounded different.

I just love running the higher timing setup.

Like Shiv says....it's much easier mechanically on the car to be making power electronically via timing advance than by spinning those turbos harder and harder.

Octane and timing is the way to go.

[onebadmofo]

How comparable ASR turbos to RB's?

[OpenFlash]

Originally Posted by chingy24

Shiv,

How much will this "extra advance" effect the guys without upgraded turbo's?

You will not need to have upgraded turbos to enjoy the benefits of this extra ignition advance. All you need is some form of reliable octane enhancer (pwm meth kit or race gas).

Ilma-- Yep, the car is so much more responsive, crisper and nicer sounding running the extra advance with lower boost. Lower boost means less spool-up time, less boost control induced throttle variation, lower EGTs, less backpressure, greater turbo efficiency, etc,. Just a win-win assuming you have the octane

[Brey335i]

Originally Posted by onebadmofo

How comparable ASR turbos to RB's?

Lol not sure if this is the thread for that but it would definitely be cool if Shiv could give us his review of the ASR turbos.

Very cool stuff. Looking forward to seeing what you guys do next

[cwn23]

Will this also work with the PPS system or just the PWM meth kits?

[tofu-]

Originally Posted by shiv@vishnu

You will not need to have upgraded turbos to enjoy the benefits of this extra ignition advance. All you need is some form of reliable octane enhancer (pwm meth kit or race gas).

i'd be more interested in seeing data on this as opposed to upgraded turbos, considering most of the market is still running the stockers. seems this would show a more realistic advantage (if any) for the majority of people.

[OpenFlash]

Originally Posted by cwn23

Will this also work with the PPS system or just the PWM meth kits?

I don't recommend using PPS kit when running extra advance. Meth flow response time is relatively slow. And flow rate consistency is relatively poor. You would have to make compromises in the tune in order for it not to "outrun" the meth kit. When meth is flowing, you can take advantage of the extra octane and run more advance. But it's those split seconds that meth isn't flowing yet (or properly) that are concerning. When running ignition advance targets that are, for the first time, higher than stock, the importance of consistent meth flow/octane is more critical than ever.

[OpenFlash]

Originally Posted by tofu-

i'd be more interested in seeing data on this as opposed to upgraded turbos, considering most of the market is still running the stockers. seems this would show a more realistic advantage (if any) for the majority of people.

You will see the same relative gains with the stock turbos (around 20hp with 2 deg of advance). It's even more useful with stock turbos since they are flow limited and simply "running more boost" isn't an option. In fact, dropping boost a bit and running more timing will result in more power, more consistently with far less engine stress. And it will, as Ilma pointed out, feel a whole lot more responsive. It's night and day once you experience it for yourself.

[OpenFlash]

Originally Posted by Brey335i

Lol not sure if this is the thread for that but it would definitely be cool if Shiv could give us his review of the ASR turbos.

Very cool stuff. Looking forward to seeing what you guys do next

They are great. Probably a little bit more power potential than the RB turbos. But with similar spool-up characteristics. But it's the upgraded wastegate actuators which make the biggest difference IMHO. With them, I can run much higher P values (in the PID boost control) without any oscillation/overshoot. Which means faster boost response with very low boost error. Even when running high boost. This was not the case with the other upgraded turbos (with stock actuators) I've tested. You could get the to work but it required some compromise elsewhere (lower P values, longer integral delays, etc,.)

shiv

[vase330]

With the nasty hot summer I think this makes for big difference. I run map 0 when temps go past 90f and maybe it's placebo but the car just seems happier. Otherwise I run map 2. Now with cold temps like in the winter does it mean this will have a lot less of the dramatic effect? Pardon my ignorance.

[OpenFlash]

Originally Posted by vase330

With the nasty hot summer I think this makes for big difference. I run map 0 when temps go past 90f and maybe it's placebo but the car just seems happier. Otherwise I run map 2. Now with cold temps like in the winter does it mean this will have a lot less of the dramatic effect? Pardon my ignorance.

The effect of getting the engine to run closer to MBT (through additional timing/octane) is always going to be dramatic. Regardless of conditions.

[Joshboody]

Now Shiv is going to swamped with rev 2.5 upgrades... while I wait, I'm going to perfect my shopping cart launches

[cstmx_ryder]

What's MBT?

Also, with the 7-11 maps, should we not touch any adjustable settings? (ie, boost, ign. correction) Or can we?

TIA