MegaSquirt Adv/Split Tables on my website
 

At the behest of a few people over the past couple of months, I decided to make some sets of Leading Advance and Trail Split timing tables for you guys. The ones I saw per the base map that was uploaded to me were pretty awful (I hope that doesn't offend anyone) so hopefully this will help you guys out. If ya'lls cars were running a bit sluggishly with poor throttle response and poor gas mileage, then this will help liven it up some. These were hand-made using my known-good timing maps from a different system with the same exact engine setups.

http://bdc.cyberosity.com/v/Technica...ch/MegaSquirt/

A few more things: Use these at your own risk. Don't hold me liable if you decide to burn these tables to your ECU, hot rod the car down the highway, then blow it up. Like any other standalone or programmable ECU, this one needs no lesser degree of proper tuning and attention paid to it. I'm assuming that these timing maps have static amount of (x) degrees of advance that's arbitrarily added to the table, with the exception of perhaps any air or water temp correction. So, as an example, if the 200kPa @ 7krpm load cell says 14*, I want the ECU to run 14* lead advance; no less and no more.

Good luck and let me know if you guys need anything else that I can hopefully help out with.

B

again thanx alot BDC, i greatly appricate your help given to us. I have much respect for you, going out of your way and not expecting anything in return.
**again everyone use at own risk!

**IAT/CLT RELATED IGNITION OFF**

cool thanks

You bet. Please let me know how they work as I'd like the feedback. I'd like to learn this system as time goes on but unfortunately I don't have one installed on a local vehicle here to play with so I need the input from you guys.

B

I'm not sure where the base map you're talking about came from, but mine have always worked well for me. I've tuned mostly NA's though.

The off-boost portion of some of your maps look similar to my NA maps anyway though.

Ken

I've got no idea where they came from but they weren't very good at all. I could see how any car running them would be running kind of sluggish with poor or lackluster throttle response as well as poor fuel mileage. I encourage others that run this ECU To try these tables out and see how their vehicles respond.

B

awesome... I just changed some areas of my tables based on these, and i'll let you know how they work out. I've got a nice 1200 mile drive ahead of the 7, and would love to get more than barely 20mpg highway, although it seems like the rough tune I had (no dyno time and playing it safe on a fresh rebuild) was extremely conservative on the spark side.

How radical is the "extended port" that these were tuned from? I have stock intake ports, minor exhaust porting, and am still a bit unclear about the effects of this on timing. As far as I can figure out, a minor exhaust port wouldnt affect it, but I have very little practical tuning experience.

I've never actually released mine to the public, but they were basically like the factory ones as close as I could get them, with a slightly higher advance.

One thing I've noticed is that the S5 NA (the place I originally created the maps) likes less advance down low, even in the low-load portions of the map than the S4 NA or T2.

The "Extend Port" map looks very similar to mine, except the 100 kPa high-rev advance is higher than I'd normally use for my NA engines. If you were using one of my NA maps on a turbo, I could see it making the engine sluggish off boost (however, Scott Clark has used that as a base for the TII's he's tuned, and he said he didn't change it off boost, just added an on-boost section). In any case that map looks pretty good to me.

If someone happened to get a hold of the base map from the Zeal engineering CD, then we purposely made the ignition a bit retarded (2-3 degrees) from what we use in our own engines. There's no way to tell what people have done to their engines, so we try to make it safe, and make it so it'll run, but so that the user will HAVE to retune it for best performance, and we even say that in the documentation we supply.

The Half-bridge port map looks odd to me, so I might be missing something, but I've never seen a map with advance in the 40's at low revs and low load... Could you explain that?

In any case, thanks for posting your maps.

Ken

yea BDC was explaining that yesterday. it has to do with the "overlap" the engine is producing. so much air escapes thru the exhaust ports at low rpms and low load. I think he will explain it better than me :)

The set of curves I've made are based directly off of those I've made for other engines that had stock or street ports. There's not much difference in terms of the VE of a motor from a stock to a street port so these curves are used across the board for them. So, for your car, they'll be alright to use. They tend towards the conservative side once under heavy load.

B

Compression ratio will have a slight effect on this and perhaps that's what it's about in that case.

These will be a good starting point, I think, and I don't think the curves ought to be changed at all.

That's the culmination of a few years of work. You'll see in the filename the text, "IGNv8", which is the 8th iteration of a set of lead and trail-split advance curves since I started goofing with partial bridge turbos back in early '03. I've made a couple more since then, but I was happy w/ how this iteration turned out and have kept it as what I give to customers. I have these same curves replicated on the Haltech (where they started) and on the PowerFC.

The advance explanation -- I know the table looks odd and there's alot of "red" area when ya look at it in the MegaTune software, but it really does make sense. The starting up with very high advance (from 0 to 100kPa) with a steady and progressive drop thereafter as RPM's rise is my attempt to better utilize the ever-increasingly thinner (less dense) charge as RPM's drop. With overlap, the slower the engine speed, the more physical time a chunk of the charge has to be scavenged out into the exhaust, bypassing any chance to perform work in the chamber. The effects of overlap are more pronounced the lower the RPM. The idea behind firing the plug earlier is based on this theory that the charge is progressively thinner the lower the engine speed. As far as how it runs, it brings alot of low-end response and life back to the engine below 3krpm.

B

One more thing I forgot to add, Ken -- the partial bridge "IGNv8" set of advance curves is what I use on my own car.

B

More or less what I was getting at. The S5 is higher compression, and they moved the leading plugs a bit, which would account for the differences.


I think our NA map was reasonably well-tuned for an otherwise stock engine; we used it to pick up a pretty good amount of torque and horsepower on our S4 NA. As I said before though, for our turbo map, I wanted people to actually tune their own ignition tables, so we gave them something to use as a starting point, and nothing more.

The "extend port" map looks very similar to what we use on our own cars, so I think it's fine, but must agree on the disclaimer.

Ken

I wasn't trying to contradict you or anything, just hadn't ever seen a table like that for a rotary. I've never worked on an engine with that kind of porting, so that would be why. I was honestly interested in the logic behind that table.

Ken

When I get home, I will load up the maps into my s5 turbo swapped 86 base. After I make sure my afr's are fine and all that, I will drive it for awhile and report back with the results. :)

Hi Ken, I don't mean to be disagreeable, but I don't agree on the approach of recommending, nay encouraging, average users to tune their own advance curves, as this is not only a voodoo-kind of black art but is also 100x more critical to engine reliability than any fuel tuning could ever be. A map, in essence, has its foundation in solid advance curves. Those come first and they generally remain unchanged unless there's some valid experimentation going on, such as changing types of fuel or making radical changes to the engine. From there, fuel-type tuning comes into play. The majority of tuning comes from trying to get fuel-type curves set to desired air/fuel ratios. To mess with spark advance curves with a level of confidence requires looking at an array of factors (this is mainly directed at the general readership here and not so much yourself, Ken): Type of fuel used, compression ratio, engine VE (volumetric efficiency) at variable RPM's, overlap and its effects, average IAT's, and many more.

The intent behind my disagreement isn't meant to "lord" over anyone or try and over-power anyone else by leaning on the "experience" excuse, but I've been doing this for a very long time, and I've learned that spark advance stuff is very sensitive and can be a very powerful way of quickly grenading an engine w/o any visual or audible indication prior. In short, that's not stuff I recommend people just start goofing with unless they have a very, very good idea as to exactly what they're doing. As an example, when I go and tune others' cars, the first thing I do, after saving whatever map they've got on their ECU to my laptop, is to wipe it and start over from scratch using a map that has a set of advance curves tailoured to the engine setup. Once those are written to the ECU, they don't change, with rare exception.

B

muythaibxr, can you post a screen grab of your timing and fuel tables? I need something for an S5 engine.

Oh I know where you were coming from. I just added the note to try and gain your confidence in what I was trying to assert behind the (hopeful) legitimacy of the way I set the advance curves up for that particular partial-bridge setup. :)

B

An example of what Ken is talking about for those that might not be familiar:

http://bdc.cyberosity.com/v/ProjectC...geViewsIndex=1

Take a peek at the differences between these two rotor housings. Yes, that's my pretty mug from about 8 years ago, sans grey hair. I was just finishing up that engine that day. Little did I know that I had mixed rotor housings. I found that out after the fact; long after I'd made a wad of power out of it for a good period of time.

There's a good thread on NoPistons.com about it.
http://www.nopistons.com/forums/inde...howtopic=69628

B

I think the point I was trying to make is that setups can vary widely as you say, and I don't want people using the exact settings I used on one car to daily drive their car when their engine setup and modifications may be completely different. I don't care if they tune it or a tuner does... I just don't want them using my maps when I have no way to make sure that they'll be good for any particular setup.

I'm not sure I agree that it's a black-art though. When I started tuning, I started out with no experience, and at this point I've tuned or helped tune several engines with good results. I don't think it's magic as long as you start with a known-safe map, and gradually and carefully change it from there. I learned myself, and while I know that some people are not going to be capable of doing it themselves, I don't want to discourage anyone either. I'm not a genius, so if I can do it, plenty of others should be capable too.

I do encourage people to take the car to a tuner if they have any doubt in their minds about what they're doing though.

Ken

Fair enough and good post. I think the intent here is a good one. I employ the same thing whenever I post a base map up on my site. I tell people to use "at their own risk". But, as far as the two sets of tables I posted up for the MS users here, it's my guess that they'll encompass just about everyone -- those with stock or street ported motors (the ExtendPort tables will work) and the partial bridge guys. I'm also assuming that the MS users here are also street-car driving guys using pump gas. I hope the specificity about my particular tables is clear.

A challenge or two for you, if you'll hear me out:

1) How many of those that you've tuned were under good load, such as 10+psi of boost? Did any of them reach, say, 25psi and vary on the octane of fuel used?

2) The magic words -- "a known-safe map". Where did that map come from and what did it take, in its genesis, for it to become safe in the first place?

The point I'm ultimately trying to drive home here is this: The higher the load, the increasingly risky it is fooling with spark advance becomes. I'm not meaning to invalidate your points as I think you take a reasonable stance, but I think, in my opinion, that you ought to stress the risk factor involved in spark advance tuning especially when it comes to load. Hypothetical comparison: Advancing spark 5* at 80kPa of load won't do much except possibly make the car run a bit goofy. Advancing spark 5* at 200+kPa can produce a great running engine for a split second and then one that sounds like a Harley with the performance of a 1970's lawnmower the next.

B

To be honest, I've tuned one up around there... at close to 20 psi on race gas (115 octane).

I took it mostly from the factory maps, and then slowly tweaked it where I thought it could be tweaked.

I can agree with that whole statement, but part of the fun of MS is learning, so I don't want to discourage anyone. I try to make the risks clear, and I think you make them clear in this statement.

Ken

BDC once again you offer great knowledge for free. I will meet you someday and give you something for you work. I had a good setup before the iron broke I was running 15psi on 91 octane. It broke on the dyno. I had no problem on the street and autocross. I plan to upgrade to meth and turn the boost up more. I did manage 390hp @ 15psi. Not the greatest but after seeing those maps I think there is more there.

I didnt take the extended port map as-is, rather I kind-of merged it with what I already had and was working up to BDC's map. The car seemed to be a little quicker, but this was just based on the butt-dyno, i dont have any hard evidence to back it up. Either way, thanks for the advice and maps!

So Ken, do you have any screen grabs?