TurboTommy

Yeah, we need alot of timing.
Unfortunately, I think we are knock limited.
A question would be: if we had, let's say, theoretical unlimited octane fuel, how much ignition lead could we run to achieve max power? Let's say at 1 bar boost. Anybody with a good estimation?
Rogue?
How about minimum best timing; are we knock limited before we even achieve that?
Back in the day, I think Autothority was using 27-28 degrees!

Rogue_Ant

Thomas - it really depends on the kind of fuel used; the turbo used; the engine specifics (bore, stroke, which head, ect), even the type of load the engine will see...

But to not just leave it in ambiguity, we have pushed pretty hard in Sid's car. His car has a nice big turbo (slightly bigger than a GT35r), and is a stroker setup, still using the 8v head, massive intercooler, and running E85 with a 5th injector injecting fuel right before the throttle-body, which further aids in cooling the intake charge. Sid obviously runs my 3D mapping, but I can pull out just the 16psi column data to show as an example: (and yes, this is a LOT of timing lead)

Rogue_Ant

And before it is brought up - yes Sid's car is a bit of a special case. I DO NOT suggest running this much timing unless you know what your are doing, and what is going on regarding your engine/car! Even then, know that incorrect timing is one of the quickest ways to hurt an engine.

One thing that should be clear to those who are familiar with tuning is that the car's VE is dropping off as RPMs increase, especially above 5500rpm - which is why you see such an increase in ignition timing. We are trying to compensate for the lower cylinder filling at high RPMs with added ignition lead.

The point of showing Sid's timing is that these cars tuning requirements (ignition timing especially) are not very typical compared to a common "tuner" 4-cylinder. A much better engine for comparison would be a SBC.

Paulyy

Josh, with respect, Let's say i put an aftermaket standalone on my 951 with some sort of base map to get the car started and ready for tuning, trailered it to a local dyno tuner and got him to tune it. Because these cars are quite rare here and as rare as they are, slim to none are street modded like mine in Melbourne. Do you think they'll get the timing right as you say it's higher then a standard "tuner" 4 cylinder engine?

Rogue_Ant

Pauly, at this point I think you would be better served by my Tuner & Logger setup... Basically it gives near full stand-alone tuning capability without the hassle. Then you can utilize the base maps I provide, which should be fairly close out of box.

If you are asking the question in the more general term - I'm not sure I could answer it, as you are basically asking me the competence of some tuner/person that I've never met... That said, tuning these cars it helps to have experience with them. (if nothing else, prior experience tuning the 951 should help to shorten the amount of time needed to develop a good tune)

Paulyy

I just asked as a general term, need to change my setup, nor even thinking about it!

TurboTommy

Thanks Rogue;
that's some crazy *** timing on Sid's car.
But, like you said it might not be a good measuring stick because of the e85 fuel; alot cooler in-cylinder temps, and alot of unevaporated ethanol causes ignition delay.

Rogue_Ant

True - Sid's car, is not a good yardstick to use for against more 'normal' 951.
So, here is a much more appropriate ignition timing curve at 16psi:

Rogue_Ant

But even this amount of timing is significantly more than what would typically be seen on a DSM/Evo/Honda. Again, this is due to the reasons I mentioned earlier.

refresh951

Is this for pump fuel?

Rogue_Ant

Yep pump fuel.
Obviously some of the cells are "impossible" to get to; no turbo setup is going to make 16psi of boost at 800rpm. So, those cells can pretty much be ignored...

TurboTommy

Would you say that this would be minimum timing for best torque, or would this be safe timing because generally we are knock limited?
Another words, if we used race gas would there be a substantial gain in power if we were to increase the timing by, let's say, 5 degrees?
And, I'm guessing a 3.0 liter might need more?

Rogue_Ant

On pump fuel, we are definitely knock limited.
On high octane fuel, it really depends. E85, for example, wants quite a bit more timing than pump gas. Race gas also can utilize more timing.
A stroker motor wants more timing, as does an engine with a larger bore...

The ideal timing advance tends to be whatever number which results in peak cylinder pressure occurring around 15° ATDC. Obviously this needs some sort of in-cylinder pressure measurement system, or an Ion-sense unit. Another method of finding best timing, is going to be utilizing a load-type dyno, and adjusting timing/fueling until best torque is found.

333pg333

Josh, are you seeing any signs of headlift or gasket issues on Sid's car?

refresh951

I know you asked Josh but I can say with certainty that Sid has had no HG issues.