I am just curious if there is some baseline formula for boost retard? i imagine it is different for every engine, But just curious as to what the general ballpark is.
At what pressure should you start to retard timing? is there any sort of ramp? like 1degree for every 2 psi?
Any advice on this subject?
i know you can do boost variable tuning on hondas because a buddy of mine told me about it. Like when you launch you'll build 10 psi but when you shift into 3rd it's a full 20psi
I imagine you can do it in any ecu though, not sure if this is the same as retarding timing at the same time though Ken.
Wouldn't it be best start by pulling a fixed amount and logging knock retard as you slowly dial it back in - that way you don't run a high risk of detonation while tuning it?
JM Graphics / The Sticker Guy! wrote:i know you can do boost variable tuning on hondas because a buddy of mine told me about it. Like when you launch you'll build 10 psi but when you shift into 3rd it's a full 20psi
I imagine you can do it in any ecu though, not sure if this is the same as retarding timing at the same time though Ken.
Uh...no. Variable boost control has nothing to do with spark timing.
ken soggs wrote:I am just curious if there is some baseline formula for boost retard? i imagine it is different for every engine, But just curious as to what the general ballpark is.
At what pressure should you start to retard timing? is there any sort of ramp? like 1degree for every 2 psi?
Any advice on this subject?
If you are knocking you know you've gone too far. That's about all the advice I can give. I have never really heard of any general scheme (I'm sure there is though). The only way to really tune it right though is on a dyno, because you can still advance too much at a given RPM without knocking and still not make the most power possible. Knock sensors themselves aren't very reliable at high RPM's anyways...and I'm sure you know that.
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Im gonna go with Whalesac with the Variable boost, its controlled by vaines in the exhaust houseing of the turbo.(atleast all the ones i have seen). I dont see how controlling spark will affect boost pressure.
JM Graphics / The Sticker Guy! wrote:Whalesac wrote:JM Graphics / The Sticker Guy! wrote:i know you can do boost variable tuning on hondas because a buddy of mine told me about it. Like when you launch you'll build 10 psi but when you shift into 3rd it's a full 20psi
I imagine you can do it in any ecu though, not sure if this is the same as retarding timing at the same time though Ken.
Uh...no. Variable boost control has nothing to do with spark timing.
uhh...no.
Your statement didn't even remotely answer Ken's question. He wasn't asking how to limit boost. He was asking how to get a rough spark table in relation to boost pressure. Anyways, since we are on the subject, you control boost dynamically with an EBC by adjusting the pulse width sent to the actuator. Retarding timing is a terrible method of boost control.
Tinkles wrote:Im gonna go with Whalesac with the Variable boost, its controlled by vaines in the exhaust houseing of the turbo.(atleast all the ones i have seen). I dont see how controlling spark will affect boost pressure.
It sounds more like you're thinking of VGT's (Variable Geometry Turbochargers) like the newer Holset Hy35's. Granted, that might work, but not really its intended purpose. It is used more to improve the efficiency over the entire power band, because a higher AR = higher efficiency (for a given pressure).
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Yeah, I am just wondering how much timing guys pull when boosting...
I have decided that i am going to stick to the 2-bar tune and just tune the max cell for max boost (where ever i end up above 14psi) I dont spend much time between 3psi and max boost... so if i am going easy, i rarely break 3psi, and if i am punching it, it flys right thru to 10+ psi in no time....
But as people pointed out to me the problem with this setup is the fact you have no timing control above 14psi (since the ECU doesn't know where you are once you peg the 2bar sensor.)
So i got myself the MSD 6212 DIS-2 Programable. And grabbed myself a the 3-bar map for it. This way i can dial in the timing all the way up to 30psi right from the msd. (i wanted it for the extra spark juice, the 6212 puts out more juice than the DIS-2 Plus and HO. but had a hard time swallowing the $750 price tag... but was looking into a window switch for meth IC sprayers, and possibly Nitrous, and saw those were like $200... and then the boost timing master was another $200, so was kinda bummed.. but then when i realized the 6212 had the boost timing and window switch built in, and everything is very customizable... plus the added spark energy.. it suddenly became well worth the upgrade from my old DIP switch style 6211 DIS-2)
Soooo... I just wondered if there was a baseline for boost retard. I know the DIS-2 comes with a flat ramp pre-programmed in it. once you hit a given psi, it just drops off at a steady rate as boost increases. So i didnt know if this was a normal thing or not.
I have a indicator light that comes on when my ECU commands more than 2* of knock retard. So i know when i see that lil light come on that something isnt right, and i compensate for it. Shockingly, i rarely see the light unless my IAT's are real high, or i am just really loading the engine. but of course it comes on quite a bit more in the high PSI's... So i was just thinking i could use the msd to start pulling timing gradually up top, as opposed to waiting for the KR to yank a whole bunch all at once.
I guess i could just data log and see where my KR creeps up... and massage those areas in the HPT spark map (up to 14psi) or with the msd if it gets above 14psi.
hmmm.... but HPT sees boost via the ecu MAP input.. which is limited to 14psi. So HPT logging wont really help me above 2bar... unless i can wire into the MSD's 3bar, and log it as an input sensor...
Will splicing into a map sensor skew its reading?
Whalesac wrote:
Tinkles wrote:Im gonna go with Whalesac with the Variable boost, its controlled by vaines in the exhaust houseing of the turbo.(atleast all the ones i have seen). I dont see how controlling spark will affect boost pressure.
It sounds more like you're thinking of VGT's (Variable Geometry Turbochargers) like the newer Holset Hy35's. Granted, that might work, but not really its intended purpose. It is used more to improve the efficiency over the entire power band, because a higher AR = higher efficiency (for a given pressure).
Whatever the proper name is, its what Ford runs with their power@!#$s. I believe they are Garrett turbos.
Tinkles wrote:Whalesac wrote:
Tinkles wrote:Im gonna go with Whalesac with the Variable boost, its controlled by vaines in the exhaust houseing of the turbo.(atleast all the ones i have seen). I dont see how controlling spark will affect boost pressure.
It sounds more like you're thinking of VGT's (Variable Geometry Turbochargers) like the newer Holset Hy35's. Granted, that might work, but not really its intended purpose. It is used more to improve the efficiency over the entire power band, because a higher AR = higher efficiency (for a given pressure).
Whatever the proper name is, its what Ford runs with their power@!#$s. I believe they are Garrett turbos.
I''m pretty sure those are VGT's, especially considering it's a diesel. The newer Dodge Cummins use the VGT Holsets.
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I was curious about this myself. I'll be boosting hopefully sometime next year, and will be using the MSD 6212 programmable as well.
As stated above, you can pull timing back from stock values then start logging, increase the timing values back towards stock until you see knock retard. (Make sure you are only pulling timing in cells where your in boost)
When I turned up the boost on my car I started by copying the low octane table values to the high octane table. Then I lowered the values in 100kpa row by hand a few degrees. Then I did some logging, tuned my AFRs. I waited until fuel was adequate and where I wanted it before I began adding back more advance.
Its an important step to have your fuel under control before you mess with advancing timing. It helps clue you in to knowing whether the knock is coming from spark or lean condition.
There can be problems retarding timing too much, this is where an EGT guage is beneficial. I think PJ as made some good posts on that in the past if you search. You should not concern yourself with adding the most advance possible across the RPM band, this is where dyno tuning comes into play. Knowing your EGTs, AFRs and what balance is optimum for making the most power at X RPM.
Ahh it's @!#$n' 4am I am just talking out my ass at this point.
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I'm curious about this as well.
If we put the IAT sensor right after the turbo (pre-intercooler), will the ECU pull enough timing fast enough to prevent knock in most cases?
2002 Cavalier 2200 5spd
Quote:
If we put the IAT sensor right after the turbo (pre-intercooler), will the ECU pull enough timing fast enough to prevent knock in most cases?
You want the ECU to see the IAT readings that are going into the motor, so after the intercooler is better.
FU Tuning
Ken, I could have gotten you that ignition for WAY less.
Thats also what I run, and when I start to tune I knock back the ignition signifigantly, then bump it up slowly after I do a log, and see whats going on.
You can add as many nodes into the boost retard timing graph as you need, and you can adjust the curve based soley on your data, but I would start with a diagonal pulling more timing as boost increases, then start to modify it.
But Black Eco described the process the best, and his info is excellent for a 4am talking out the ass post.
