Can't advance timing
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Joined: Aug 2002
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From: Sydney
Can't advance timing
Well, it's been tried and failed...
I finally got my SMT-6 in over the weekend, thought that it would be great. One of the first piggyback computers to be able to control timing, for under $500.
Well, we advanced timing throughout the whole range 1 degree. Nothing. Not so much as kilowatt gained anywhere. So we advanced it to 2 degrees. It starts pinging at the end of the two camshaft profiles (IE 4000-5500 and 7000 to redline) and loses power almost everywhere. Bummer. It looks like the car is pretty well tuned for premium fuel. Perhaps a bit of octane boost would have let it tune a bit higher, but I want my engine tuned to be daily drivable, not on special fuel.
We can successfully retard, which means we can use it for a turbo, but as a naturally aspirated engine tuning tool? Well, 5-10kw was the best we could get by leaning out the fuel. Nothing from timing advance.
Soooo. my advice is, if you think a piggy back computer is better than V-AFC: Don't waste your money unless you're going custom turbo.
I finally got my SMT-6 in over the weekend, thought that it would be great. One of the first piggyback computers to be able to control timing, for under $500.
Well, we advanced timing throughout the whole range 1 degree. Nothing. Not so much as kilowatt gained anywhere. So we advanced it to 2 degrees. It starts pinging at the end of the two camshaft profiles (IE 4000-5500 and 7000 to redline) and loses power almost everywhere. Bummer. It looks like the car is pretty well tuned for premium fuel. Perhaps a bit of octane boost would have let it tune a bit higher, but I want my engine tuned to be daily drivable, not on special fuel.
We can successfully retard, which means we can use it for a turbo, but as a naturally aspirated engine tuning tool? Well, 5-10kw was the best we could get by leaning out the fuel. Nothing from timing advance.
Soooo. my advice is, if you think a piggy back computer is better than V-AFC: Don't waste your money unless you're going custom turbo.
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Joined: Feb 2001
Posts: 2,895
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From: You wish
Sunder,
What you've probably run in to is the rather interesting way Honda handles the intersection of ignition timing and knock retard on its modern ECUs. Its a sticky little methodology, and I'm not sure why they have chosen to do it the way they have - but they have.
Unfortunately, this all I can disclose as its not my discovery to share. But, suffice it to say that, especially on earlier model S2000s, more ignition timing in the right spots does provide more power. Whether or not we can take advantage of that with piggybacks may be another story all together.
UL
What you've probably run in to is the rather interesting way Honda handles the intersection of ignition timing and knock retard on its modern ECUs. Its a sticky little methodology, and I'm not sure why they have chosen to do it the way they have - but they have.
Unfortunately, this all I can disclose as its not my discovery to share. But, suffice it to say that, especially on earlier model S2000s, more ignition timing in the right spots does provide more power. Whether or not we can take advantage of that with piggybacks may be another story all together.
UL
Thread Starter
Registered User
Joined: Aug 2002
Posts: 611
Likes: 0
From: Sydney
Hey UL,
Thanks for the info... I wish you could be clearer to disclose on the Knock vs Ignition timing... We do notice that the engine does genuinely ping at 2 degrees advance. You can tell by the AFR and the shaky torque graph.
However, upon more careful tuning, we've found 1 spot where we gain about 3-4kw from advancing 2 degrees, and a a couple others, where advancing 1 degree gives very marginal gains.
I'd hardly call it an unqualified success, and the gains are barely worth the increased risk of detonatation in case of a bad run of fuel, so we're going to advance around 6000rpm by 1 degree, and leave all others alone. I am going turbo in a couple months anyway.
Thanks for the info... I wish you could be clearer to disclose on the Knock vs Ignition timing... We do notice that the engine does genuinely ping at 2 degrees advance. You can tell by the AFR and the shaky torque graph.
However, upon more careful tuning, we've found 1 spot where we gain about 3-4kw from advancing 2 degrees, and a a couple others, where advancing 1 degree gives very marginal gains.
I'd hardly call it an unqualified success, and the gains are barely worth the increased risk of detonatation in case of a bad run of fuel, so we're going to advance around 6000rpm by 1 degree, and leave all others alone. I am going turbo in a couple months anyway.
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