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Meat Popsicle
91 CRX Si
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2,936 Posts
Discussion Starter #1
I'm ready to rent some dyno time to tune the ignition map but I have a few basic questions. From what I've researched, you should gradually increase timing while listening for detonation. Once you start nearing MBT, you'll start to see little to no increase in torque when adding timing. Once you hit this point, you can pull back the timing by a few degrees and call it a day.

So this all seems simple enough. I planned on doing an initial pull on the dyno, looking at the torque curve, and adding timing where necessary to smooth the curve.

So lets say I have a smooth, flat torque curve and I haven't heard any detonation. How should I go about increasing timing overall? I would think that it would make most sense to work a few columns at a time, probably the low RPM/low boost rows/columns first and working my way up. Am I thinking about this correctly?

Apologies in advance if this is way the fuck off track...
 

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Brokedick Millionaire
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40,297 Posts
This is where you need to nit pick the brain of Blundell and others. It was "interesting" comparing the old tuning ways (timing locked out at 34 BTDC) before MBT was more understood.

What once was a mess....



cleans up nicely....



Still has the AEM TQ peak at 4750 but look at the dips that were removed...
 

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Meat Popsicle
91 CRX Si
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2,936 Posts
Discussion Starter #3
Agree bone, just don't know the right way to contact someone like Dave. Pgmfi.org seems to be gone again so...

They did a great job cleaning up that torque curve and that's how I planned on approaching it...smooth out the dips as best I can.
 

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Meat Popsicle
91 CRX Si
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2,936 Posts
Discussion Starter #6
Hmm I figure the method of finding MBT would be the same...identifying the point where adding timing either stops producing or reduces torque and then pulling it back 1-2 degrees.

I would assume that if you're octane limited, detonation would simply occur earlier.

What am I missing?
 

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Registered
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3,720 Posts
You have it right. Just make sure you use a dyno with a brake. Lock it at a speed and move through the load cells finding the knock limits and MBT through those cells.
That would be a thorough dyno tune. It wont work on an inertia dyno.

You can also just get it close enough in the low load by street tuning, and just tune the highest load cells using the above method. Much quicker. You probably wont be able to tell a difference afterward.
 

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Classic Man
Civic
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16,355 Posts
What I am trying to say is get some knock ears to listen for det. It can still make power and have some pre ignition issues and detonation issues. The type that blows head gaskets, takes out rod bearings, etc, not pistons and sleeves.
 

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Meat Popsicle
91 CRX Si
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2,936 Posts
Discussion Starter #9
What I am trying to say is get some knock ears to listen for det. It can still make power and have some pre ignition issues and detonation issues. The type that blows head gaskets, takes out rod bearings, etc, not pistons and sleeves.
Cmon bruh, I wasn't going to go into this blindly ;)

When I mentioned listening for detonation in my first post, I meant a det can. In fact, I'm actually using most of the write-up that you did on building one.
 

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Meat Popsicle
91 CRX Si
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2,936 Posts
Discussion Starter #11
It was the single best thing I ever did when learning how to tune, was learning what ping sounded like.
And that's my biggest concern. I've listened to this video:

https://www.youtube.com/watch?v=GGJZ6kKzLus

And sure, it's very obvious here where it's filtered but I'm concerned that the difference won't be so noticeable with my det can. My engine is already rather 'clicky' with the web cam and the tight valve lash settings. Maybe it's one of those things that you know once you hear it..
 

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Classic Man
Civic
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Its not super obvious what it sounds like and thats why a lot of people would rather just pay a guy like me to do it. :p

But Ill tell you what, when you hear it, you know.... "That was a hell of a lot louder/sharper than just engine noise"
 

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Classic Man
Civic
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Meat Popsicle
91 CRX Si
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2,936 Posts
Discussion Starter #15 (Edited)
Its not super obvious what it sounds like and thats why a lot of people would rather just pay a guy like me to do it. :p

But Ill tell you what, when you hear it, you know.... "That was a hell of a lot louder/sharper than just engine noise"
So I *think* I hear some detonation between 3-4K at 6-7psi but it's difficult to tell. I think I'm just going to pull like 4 degrees and see if it goes away.

Web cams recommended valve lash of .007" and .008". I'm wondering if tightening this up to .005" and .006" will help reduce the valvetrain noise.
 

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Classic Man
Civic
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16,355 Posts
6-7psi? Unless you got serious boost leaks or other issues, its almost impossible to blow something up with that little pressure.

You could pretty much just run 94 octane and leave timing unchanged and it should be ok if AFR is good and the fuel has decent octane.
 

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the artist formerly known as drexelstudent11
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3,983 Posts
6-7psi? Unless you got serious boost leaks or other issues, its almost impossible to blow something up with that little pressure.

You could pretty much just run 94 octane and leave timing unchanged and it should be ok if AFR is good and the fuel has decent octane.
yeah, think of how long everyone kept their FMU'd with 2 degrees of dizzy retard garbage setups together for back in the day - honda motors are pretty damn forgiving
 
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