Hyper-advancing ignition for hi rev cams?

[isaac]

So I stumbled on something tonight that I'm sure somebody knows about but I hadn't seen in any of the maps I'd gotten from Kenny, John, or Mark. It's hyperadvancing the ignition curve.

Since I've got a K cam, I've got a low end problem. This car really doesn't have any balls below 3,000rpm, and thats even with the 6 deg advanced cam. The problem of course is that none of the engine's characteristics are suited to low end operation.

The cam doesn't come into the powerband until 3,000, and only then does the turbo reach full spool.

So tonight, based on the theory that anywhere I don't have power needs more timing, I went nuts. In the square on my 12x12 map bordered by 1,500rpm-3,000rpm, and 100kpa-150kpa, I advanced the timing at least 50% more than it was before.

Just to give an example of the maximum craziness I envoked on the car, here's how my 150kpa spark map changed: Before, it was 18 deg at 1,500, rising to 23 deg by 3,000rpm, as part of a full gradual curve like that. Now, it's 28 deg at 1,500, rising to 34, 36, and then down to 32 by 3,000rpm.

Add 10% to that, and you've got my new 120kpa map in the low rev range. Add another 10%, and you've got my new 100kpa map.

Here's my map, to compare with yall's. POST YOUR MAP! That way I and everybody else can compare.

http://www.pbase.com/image/50398947.jpg
As you can see, there's a big bump in advance in that block, then it drops again to avoid detonation. This isn't the farthest I could push this map. I plan on driving around and advancing it even more if nobody here gives me a reason not to. It seems to like it a lot, and accelerates more smoothly down low because of it. There's gotta be a limit though.

[linuxman51]

those aren't obscene numbers for a 8v, but they're a little high in the midrange. you need to hook a wideband up and tune the ****er, and then strap it down and see what your power curve looks like.

[The Aspirator]

That's really interesting, I can't say I've spent much time tuning the low rpm low boost bins of the ignition table, just did them so they don't ping. Your method should make the low end more bearable! Well when I get my car running we'll see what a B21FT acts like under MS powar.

[PetesDustyVolvo]

Also using a K cam advanced 6 degrees here... this table gives me better low end than LH

up top its a little more iffy... waiting for my LC-one!1! =p


http://img283.imageshack.us/img283/5681/sparkmap9ex.jpg


edit: wow can you really run 40* advanced at 100 kpa and ~2500 rpms??

insane

unrelated Q: whats that 531 bolted down to isaac? B23F? B230F? B230FT? and what turbo? intercooler?

PS: whats your idle like at ~20* advanced?

[kyle242gt]

Hyperadvance? I got cher hyperadvance right here. Since refiguring my TA a monthish ago, I've been exploring the upper limits of timing. Let me know what you all think. Yes, I know I need to get on a chassis dyno.

I haven't really tuned the line at 140, since my car either runs about 5PSI or 15PSI, seldom in the middle. But after reading your numbers, Isaac, and being admonished to run less total boost yesterday, I plan on lowering max boost to 150 or thereabouts. I'll try your timing approach.

Anyway, real world driving shows GOBS more power at 100Kpa, about the same cruise MAP (8" vac, whatever that works out to, 70ishKpa?) and (curses!) the about the same MPG. I'm still getting the occasional stutter, so I've still got some work to do...

Unopened 92 B230FT, Kcam, 15G, stock IC, greentops. ps- any critique of my high boost timing is welcome, and I'm running 87 octane CA gas :barf:

[isaac]

edit: wow can you really run 40* advanced at 100 kpa and ~2500 rpms??

unrelated Q: whats that 531 bolted down to isaac? B23F? B230F? B230FT? and what turbo? intercooler?

PS: whats your idle like at ~20* advanced?

It's working just fine right now at 40 degrees, so I might even advance more. I don't really know how it's working of course. At part throttle, in vacuum, in that range it's pretty sensitive to timing and only gives me so much before bucking.

Hard parts are mid 89 B230F+T with about 9.55:1 compression, 15g, and stock IC. Idle got better the higher I advanced it for some reason. Could have to do with me running a rich idle.

Kyle, it looks like you're going buckwild with the timing there. It's still looking a little weak up in high boost, but that's probably the 87. Still, I'm running 93 octane and even I'm not running that high a high rev timing at 120kpa and ~140kpa. I might try it out. I just know I'm not even close with fuel, so I don't like pushing it. Down low I'm not so much worried about pushing the ping threshold because those are just load pings instead of high rev hard detonations.

[PetesDustyVolvo]

It's working just fine right now at 40 degrees, so I might even advance more. I don't really know how it's working of course. At part throttle, in vacuum, in that range it's pretty sensitive to timing and only gives me so much before bucking.

Hey, maybe you're running fairly lean even in low boost and getting away with it? :e-shrug: I'm encouraged to try more timing anyway. Sorry for the interrogation here :-P. How did you arrive at your fuel table? MST3K?

As for upper boost, I'm convinced cali is a completely different game.

PS you silly 15gers, :cool:

[Captain Bondo]

The hotter your cam is, the more low speed advance you will be able to run. You have just successfully reproduced what Volvo did when they made 017 distributors for k-cam motors in 1979. The lower the ve of the motor is, the more advance you can run.

There is a specific concept to remember when mapping ignition, and John follows it on his car now and he can tell you it works.

You have a given fuel octane. Your specific motor can produce a certain amount of torque with this octane. Remember that combustion pressure and torque are literally the same thing for our purposes.

Your goal is to produce this maximum cylinder pressure for as much of the powerband as possible. Looking at timing as a "number" can get you in trouble.


Your motor will narturally want to produce more torque at a certain rev range. The motors usually do this between 3000 and 4500rpm, depending mostly on the cam and how boost comes up.

What you need to worry about is not the timing number itself relative to zero degrees, the important part is what the timing is relative to engine speed.

People tend to make a nice steady ignition curve, they advance the whole curve until they get pinging, and then retard the whole curve.

What you should do is only retard where it pinged, and then KEEP ADVANCING the map before and after the torque peak. By adding more advance you broaden the torque peak
Adding more advance after the peak helps keep the torue high in the upper rev range, especially past 5250, which is the KEY to making power.

Advance below the torque peak increases bottom end power. If you retard the timing at low rpm for the purpose of spool-up, make sure it's only retarded from 0psi-30% of max boost.

I've seen a few maps where people do the "spool up helper" ignition strategy, but they retard across the board which still helps but it is at the expense of off-boost response and bottom end power once boost comes on. In vaccuum you still need the advance, and as soon as boost starts to come on, you want the advance back to take advantage of it. It's just in between.

But yes, this "hyperadvancing" is just compensatiing for the fact that the motor's ve is not very good at each end of the rev range.

John and I did this on the top end to his car before it left this earth, doing it to the bottom half was next on the agenda although we never got this far.

I hope this helps. But basically yeah, most people have way moe room for advance before and after the torque peak but don't take advantage of it becuase the motor pinged in the midrange.

edit: holy crap this was long. sorry guys. :oops:

[The Aspirator]

This is the map that Kenny is reffering to. We spent a long time tuning the top end but didn't really get around to the bottom end. I would have LOVED to see a torque graph for this tune, I'm pissed it blew up. :-P We were running just under 200kpa and it started pulling like a mad man above 5000rpm. Wow Isaac you're running even more timing than I was in the mid rpm range! Looking back at it, my mid range is pretty retarded, but it must have been because it would ping at that low rpm. That's why it just racks up higher and higher.

http://www.vipinfoservices.com/john/images/megasquirt-kenny-tuned-powar.gif

[Les, slight limp]

Hi,

I don't know if its any use, but advance ramps on distributors look remarkably like your computer stuff. The recomended maximum advance for a corotid/heart shaped compression chamber is static + 32-34 degrees. This should be at its max by 3200-3400 rpm, obviously with a dizzy the advance stays at this figure.

This is according to what iv'e read i could be wrong, i'm sure cap bondo can supply better information, just trying to help. Les.

[Captain Bondo]

Yeha exactly, we scooped out the midrange a bit becuase I think the boost spiked about 2psi around 4k. Also worth mentioning we hadn't really done the pre-3500rpm part of the map yet. The B21ft is going to be trickier to tune I think.

Les, as you say and I sorta alluded to, the dizzy curves are a good place to start- although they don't have the flexibility to literally have a big "notch" in the middle of the curve to compensate for a boost spike or etc, they are a "best fit", and are a good relative starting point. Most of the maps posted seem pretty close to reality in the midrange- but that's because they were mostly dictated advancing a curve intil it pinged. With programmable we don't have to settle for that though becuase can have a curve that more closely represents the actual burn time of the motor as we have we none of the contraints mechanical advance imposes. :rockon:

[volvorsport]

that nice NA B230 had an MBE system , and had around 40-43 degrees advance , that was the sweet spot.

[PetesDustyVolvo]

wow, my new spark map:




http://img6.imageshack.us/img6/3466/untitled5kj.jpg



:rockon:



needs more work but cool!!! its actually a lil bit faster

[Captain Bondo]

Why do you dump 10 degrees almost across the board from 100-120 and again form 120-140?

[PetesDustyVolvo]

Why do you dump 10 degrees almost across the board from 100-120 and again form 120-140?
because i'm not really using it (it being boost) much these days, trying to get good gas mileage and waiting for my innovate LC1 to get delivered

[Captain Bondo]

right ok, thought that must be it. :)

[PetesDustyVolvo]

btw

i have a hunch that maps that pop up from autos vs. manuals SHOULD look a little different in the low rpm low kpa area

i popped it kenny's (the other one :-P) "531 map" from another thread at one point and when i hit the gas it almost felt like i was driving manual :grrr::pow::rant: almost

i just have a feeling im the only one with an auto in this discussion

[linuxman51]

i popped it kenny's (the other one :-P) "531 map" from another thread at one point and when i hit the gas it almost felt like i was driving manual :grrr::pow::rant: almost



???

[PetesDustyVolvo]

your map (from your 531 head car) didnt have much pull on an auto tranny idling in drive but when i touched the pedal it started to pull pretty hard... it gave the feeling of the sort of "rev"-> drop the clutch that im prone to doing...

i know its a nonsensical and random thing to say. i was just thinking that mauals dont spend much time below 1200 rpms, at least not when I drive them. it felt like the map started at 1200 even though it had a line below that.

dunno why i mentioned it... you all should just ignore (and probably do) about 75% of what i say

[isaac]

Advance below the torque peak increases bottom end power. If you retard the timing at low rpm for the purpose of spool-up, make sure it's only retarded from 0psi-30% of max boost.

I've seen a few maps where people do the "spool up helper" ignition strategy, but they retard across the board which still helps but it is at the expense of off-boost response and bottom end power once boost comes on.

What? I've never heard of that. Those would seem to go against what I've been doing. Why would retarding timing help spool? BTW excellent writeup.

[Morley]

What? I've never heard of that. Those would seem to go against what I've been doing. Why would retarding timing help spool? BTW excellent writeup.

Retarding the ignition a lot moves a part of the combustion out into the exhaust channels/headers, thereby spooling the turbo.

Watch out for crazy EGTs....only used on launches etc. And pretty tough on the material.

[isaac]

Oh, well then screw that idea.

[kyle242gt]

Yeah, anti-lag is not a real good idea :omg:

So, I set my boost to 160Kpa and tried my damndest to up the advance. No love. I didn't play with the advance after 2800, but in the 1500-2400 range (when the rockemsockem 15g is spooling up) I can get about 17 or so.

BTW - I harp on this every now and again, if you're not using MSnS-E's boost control, you're missing out.

After I get some other projects out of the way, I'm going to run water/alc injection. :evil: I was going to save that for next summer, in case I nuke my M46, but is sure looks like crappy fuel is holding me back at even 10PSI :please: :barf: :rant: :grrr:

[The Aspirator]

Kyle it's in the upper rpm where you really want to play with advancing the ignition, especially at full bewst. I'm not using the boost control yet but I really want to!!! Maybe in a few weeks after I get this engine sorted out I'll try it, really looking forward to it.

[kyle242gt]

Hi John - I've been upping my timing at 160, A LOT... I'll post a map tonight or tomorrow.

But:

HOLY SH!T!!! I see what the fuss is about Kcams. This thing is a rompin stompin rip snortin beast at about 3500+.:-D :badboy:
//edit:
Okay... here we go. I added 2-9* from 1500 to 6000 at 140, and 3-11* at 160Kpa. Notable is the 11* increase at from 5000 up at 160Kpa.

This thing hauls ass. It was a little nerve wracking constantly adding timing and then flogging the car, white-knuckled for the first tiny ping, and then WHACK the cam comes online and ZOOOOOM! I gotta lay blame for not taking John's advice sooner on my blind goal of 15PSI. I'll whip out the trusty :roll: Gtech and do some 0-60/1320 runs for giggles. I was around 7/15.5 last time I did it. Butt-O-Meter says it's faster at 10PSI than 15.

[The Aspirator]

Seeee! I told ya so :booty: , hahahahaha. I'm really glad it's working out for ya! It's just one of those things, you think your car is tuned just peachy keen, then you try something like this and you almost crap your pants. That's exactly what happened when Kenny and I went out tuning back in August. My car was faster than it had ever been before. Then I blew the **** up.... :-P. (but don't worry, my engine was doomed, yours will be just fine)

*edit*
Dayum son, das a lotta timing! Wicked.

[The Aspirator]

We played with the 242 today, hot damn tight squish and a powerstroke really does work! I think I advanced the ignition well into the 30's at 200kpa, and mid 20's at 225. It pinged a little bit at 4500rpm but otherwise didn't ping anywhere.... mebbe that means there's more to it! This tune though completely changed the car, it's even more of an animal. Gotta dynotune one of these days!

[tequila_gundam_no_chaser]

Oh, well then screw that idea.

For an example of how well it works, set your car to fixed trigger angle, then drive it up an incline slowly. Notice how the turbo spools just off idle, but watch your coolant temps.

[ovlov760]

What? I've never heard of that. Those would seem to go against what I've been doing. Why would retarding timing help spool? BTW excellent writeup.
I've messed with this strategy a bit and I think it definitely helps spool. Makes me wish I had more than 12x12 though.

[blkaplan]

I have about 25 degrees timing @ 1500 rpm and at that point i have full boost... ie 7psi

[Hank Scorpio]

I have about 25 degrees timing @ 1500 rpm and at that point i have full boost... ie 7psi

Ya I used to run butt loads of ign timing off boost, always helped spool a bit earlier. Course I also was running but loads of cam.

[blkaplan]

Ya I used to run butt loads of ign timing off boost, always helped spool a bit earlier. Course I also was running but loads of cam.


mine is just due to M cam, 9.8:1 compression, and a t25 peashooter