Cyclone manifold Tuning

[prove_it]

I did ask over on ECM forum, but thought I'd see what the experts over have to say. I've been wondering about the cyclone manifold and timing curves. Right now I'm just using a modded EVO timing map in link. I'm wondering if I should have a different curve based on the activation point of the runners. Make sense? Part of me says no, since the increase in airflow will put the reference cells lower into higher load, but not sure. Also should the pre-activation curve be more aggressive?

I am on E85, but would like to answer this for anyone needing the reference.

 

[swe_gvr4_1991]

Short answer, I don't know.

Long answer; go out and find a long stretch of road and do a 4th or 5th gear WOT pull from a slow rolling start so that you cover the broadest RPM range. You must go say 1000 RPM over the Cyclone activation RPM.

Then check out the log for tell tales on stuff. Could be dips or peaks just where the Cyclone activates.
Then do some good guesses and massage those RPM timing cells.
Do another identical WOT pull and log.

What changed in the logs? There you have a starting point.

If you export your logs to CSV format, maybe we can help out too.

Good luck!

 

[belize1334]

The cyclone manifold will change the effective volumetric efficiency of the engine. So if you're running SD, where you have to calibrate the ECU for VE, then you'll need new VE tables for every variance of the activation point. Or, alternatively, you could do one VE map for the whole rpm range w/o the dual runners, and another map for with. Then you could stitch the maps together at whatever rpm you choose to activate.

BUT, if you're not running speed density, you don't have to tune anything. You place the cyclone trigger at 4100rpm, which is roughly where the two curves intersect, and you're done. The MAF measures airflow and then ECU then calculates load. It's no different than raising the boost a little at a certain rpm point - you get a little more airflow and the ECU jumps to the appropriate load cell.

 

[prove_it]

I am running SD, and that's what I was wondering. My activation point doesn't feel that bad, but I can tell it needs work.

 

[swe_gvr4_1991]

For pure research purposes running SD on the Cyclone i would do this:

This way you will know the exact timing and AFR target.
Also notice the same value on the VE map across the Cyclone activation RPM range.

This is how i personally would do it to see the exact behaviour of the VE once the runners open. This way i would know how much it affects AFR and therefore i need to adjust the VE appropriately.

Hope it makes sense. The car will drive like crap under this test but like i said it's only for 2-3 pulls on maybe a lower gear like 2nd or 3rd. It would be sufficient with a lower gear if logging on a fast logger like link.

Edit: I would also do some runs with the "proper" VS map and compare.


Edit: Resized the pic.

 

[belize1334]

So there are really two questions here.

1) Where should the cyclone activate?

2) How should the tune be altered to take advantage of a given activation point?

This is how I would approach it. Opinions may differ.

1) Activate it at 4100rpm. That's where the JDM ecu did it and that's where Keydiver's chip does it on my setup. To convince yourself that this is the place to do it you can look at a dyno comparison I did a while back. click The thing to note is that blue curve never dips below the red curve and there is no dramatic jump in power at the activation point (4100). That means the activation point is well positioned where the two different curves would intersect. This should be true regardless of the turbo choice or boost level since it affects resonance in the head, which is independent of boost. It MAY be different for strokers but nobody has said anything definitive about that yet.

2) As for your tune. I'd say get it dialed in to the appropriate AFR everywhere with the cyclone disable (always open). That's gonna be the same as a 1G manifold tune. Then enable the cyclone manifold and drive it around for a while. You want to be logging in open loop and keep out of the boost. What you should see is a consistently lean condition that depends on rpm. So what you want to do is determine the scaling as a function of rpm and then apply it globally. You can do this by creating a compensation multiplier that depends only on rpm, or by manually rescaling the VE with a different value for every column. To determine the scaling, look at your logs and divide the logged AFR by your target AFR and plot that against rpm. There should be an obvious trend. Multiply that by your current VE and bob's your uncle.

 

[prove_it]

Speaking of resonance in the head, do cams, OS valves, and smoothed ports effect this resonance?

 

[belize1334]

Supposedly it's helmholtz resonance so all that matters is the cross-section of the runners, the length of the runners, and temperature (which corresponds to sound speed). These values can be combined to determine a resonant frequency. Doubling the cross section doubles that frequency so by having the option of 4 vs. 8 runners you effectively double the area with the flip of a switch and your manifold, which was originally optimized at around 6k rpm gets a second resonant peak at 3k rpm. The biggest departure from this would probably come from boost pressure in the form of temperature, which increases the sound speed. But remember, temperature is measured in Kelvin in this scenario. The difference between off boost (say 80 degrees F - that's roughly 300K) and full boost (150 F is roughly 340K) is negligible. Sound speed goes as the root of temperature so even a 10% increase in temp relative to absolute only gives you 5% change in resonant frequency. Real world - should the activation point and tune be altered to account for cams, porting, valves, etc? Probably. A lot? No. All of that *should* be a secondary effect - making it ignorable unless you're trying to break records.