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?

Nope, no screen grabs as of right now. I'll check my laptop at home to see if I can find the original S5 maps I used.

Ken

Hopefully everyone knows this already but if you are going to try any of these settings, make absolutely sure you've got enough fuel!!! Start rich and tune down. Don't automatically assume your fuel settings are going to work good with these timing settings. Your porting and turbo used will also affect how well these work on your car. Try them. Just be careful and don't automatically assume all will be instantly well when you load them in. There is always some tweaking to be done.

yea, that was why i was working up to them, so i could stay on top of fuel tuning, and just to incrementally make sure everything was working right and sounded/felt fine

Naaah Fred, it just automatically works. Just wave your magic wand and "poof!" instant horsepower and torque! Don't you know that's how cars work? :D

B

hey BDC im working on a HB high comp turbo setup(s4 rotors)and im close to start
the motor but i dont have a base timing,split tables,i been searching for days but there is no info about running a BP with MS,did you have any tips or ideas that are you willing to share thank Joey

he has a timing map on his link for a halfbridgeport

Bdc could you please give me some more details on the engine that was used with the The Half-bridge port map with the advance in the 40's such as witch housings, what rotors and what front pulley?

It's from mine, primarily. S5 4-port turbo block, S4 turbo 8.5:1 rotors. Front pulley? Atkins Rotary aircraft setup, but that shouldn't matter.

B

so i need to play a bit if i use this maps cause my setup use high comp 9.4.1 rotors
and s4 turbo housings,by the way what injector combo and turbo are you running BDC?Thanks Joey

Eh, take out 1* across the board, Joey. It's a pump gas setup and it already has a fair bit of retard in it under load so the change from 8.5:1 to 9.4:1 won't make much diff but wouldn't hurt to start on the conservative end.

My injector combo is 720/1680 at a 40psi base pressure.

B

The reason why i ask is i was wounding how you're car was running good with the leading plugs firing on the rotor flank,the pic is a s4ts rotor, front pulley,and housing @45 degrees of advance?(give or take 2 degrees depending on how the front pulley was bolted on)
http://i58.photobucket.com/albums/g2.../s4t2-rh45.jpg

Then i started to think maybe he had s4 housing with s4 rotors in a s5 engine with a s5 front pulley witch would make you think u are firing @45 when u are really firing @ around 35 the front pulleys are different between the s4 and s5 engines the is around about a 10 degree differance and the s5 pulley is a tad bigger (see pics)!
red pulley is a s4 silver is a s5
http://i58.photobucket.com/albums/g2...9_100319AA.jpg
here is a pic of what i mean buy rotor flank the X (to give an idea) is were u would be firing on at 45 out side of the chamber!
http://i58.photobucket.com/albums/g2...rotorflank.jpg
Here are pic with the red s4 pulley set at -5 factory mark then with the silver s5 pulley installed with out moving the e-shaft see the differance!*(NOTE: each mark is 5 degrees)
http://i58.photobucket.com/albums/g2...9_095951AA.jpg
10 degrees differance (give or take a degree or 2)
http://i58.photobucket.com/albums/g2...9_100058AA.jpg

More Pic's
s4 housing rotor and pulley all in the below pics!
s4 @ 30 degrees advanced
http://i58.photobucket.com/albums/g2.../s4t2-rh30.jpg
s4 @ 35 degrees advanced (see the rotor flank starting to cover up the leading plug hole!)
http://i58.photobucket.com/albums/g2.../s4t2-rh35.jpg
s4 @ 40 degrees advanced (look were the flank is now)
http://i58.photobucket.com/albums/g2.../s4t2-rh40.jpg
If I am wrong about the s5 front pulley and u do have a s4 front pulley installed,
Please explain cause i don't under stand how it would run good firing out side of the chamber if it would even fire at all?FYI buy no means was any of this meant to offend you what so ever, i think it is great to have a experienced rotary tuner on the ms forum to give out pointers

thanks BDC,i will get back to you with the results

Looks like I need to advance my timing 10 degrees after reading about the pulley marks. I'm currently using series 4 housings and using the Mazdatrix/Racing Beat underdrive pulley. I ended up marking the factory leading -5 degree mark on the new pulley and set it to that. I used the series 5 pulley to do this however by putting it on, moving it to the mark, taking it off, and then marking the new pulley. But that's for series 5 housings though. Looks like I've been 10 degrees off this whole time. Also, I decided to use BDC's timing map for my streetported 4-port (N/A application actually)
Brian

so twister do you think that i should change my front pulley to a S4 turbo(i have a s5 turbo installed now)to take care of this 10 degrees diference,i already subtracted 1* all around my advance and trailing settings like BDC sugested but i want to be safe before i start this motor up thanks for inputs(BDC and twister)

You're VERY right about the difference in pulleys!! This is something I ran into a few years ago by accident. I had no idea I'd mixed up the pulleys and front hubs. Having them mixed up will send your advance off about 13* too far forward or too far behind. It's therefore imperative to make sure that you keep the pulley/front hub combo together.

Mine is correct -- I used a Racing Beat pulley/hub (underdrive) unit with known-good timing marks to mark my pair. This is a common enough problem on the FC's that when I go out of town to tune cars I take a known-good combo with me incase I detect that their's is off.

B

Twister7, thanks for taking the pictures of the rotor in the housings. I need to take a closer look at this. The only place I'm having it fire that early is at low RPM pretty deep into vacuum. Otherwise, it will go about 40* and then forward. Based on this, I need to see if I'm firing the lead too early by accident. It does seem to run and function just fine. I'm running S5 rotor housings, btw.

I've got some driving time today while I run an errand up to Dallas and back. I'll try goofing with this and see if it makes any appreciable change by pulling a bit of adv out and see what happens.

B

All i know so far is u have to keep the front pulley and rotor housing combo the same . s4 housing with s4 front pulley s5 housings with s5 front pulley! read my replys

I am not seeing any differance when swapping a s4 pulley hub for a s5 pulley hub are u ? If so let me know so i can check a few more (i have 10 or 15) and make sure the s5 one i pulled is a s5, also i don't see any differance in the front cover from s4 to s5 other than the s5's pointer is higher up to allow for the hair bigger s5 pulley,,only thing left is the e-shaft i really don't think mazda would change the key way but who knows, i need to figure out a way to check that!

When i was search a wile back i did come across a .txt file that was said to be a stock s4 n/a and a stock s4t2 timing map it was on the nopistons forum! The map if it is a stock s4t2 map did show 42.5 deg advance at 6400 to 7168 at what i think is very very light loads (off throttle like loads) and 40.4 at 3072, but because Mazda does not use a map based system I am not sure.At 42.5 about half the plug hole would be covered buy the rotor flank.Any ways here they are!
FYI like i said i don't know if these are stock maps for sure or not!!!!

Oh ya if u are running s5 housing one need for more advance might be (Rotary engine by Kenichi Yamamoto on page 53) spark plugs installed away from the minor axis in the leading direction will reduce emissions but deteriorate the fuel consumption because the initiation of combustion in the less squishing area causes slow combustion speed! (THIS MAY CAUSE IT TO NEED MORE ADVANCE)

As far as I know, the keyway has NEVER changed on the eccentric shaft for the 13B since the 70's up until the current renesis engine. Also, as far as I know, the pulley hubs have stayed the same from 79-91. I'm only aware of the actual pulleys being different between series 4 and series 5 housings.
I just need to go find out now where I should EXACTLY mark the factory -5 degree mark on my Racing Beat pulley for series 4 housings.

^^do you have a link or pic??

The crankshafts are no different in terms of the front keyway aligning TDC at 9 o'clock, but they most assuredly have changed front hubs somewhere in that mix. I wound up having 2 or 3 different kinds from what I recall. It was aggravating enough to force me to not only make a known-good pulley/hub combo but also carry one with me. I've seen cars that were 13* too far advanced across the board as well as 13* too far retarded. Happened on my car once, actually.

B

Edit: to bold and stress a particular point

No, no, no -- Static timing will not change from housing series to housing series even though the lead plug placement on the S4 housing is higher than the latter! If anything, it may demand a closer look at when spark is being fired under load if the compression ratio of the motor is the same between the two, but as far as setting a known good timing mark? Absolutely not. TDC, regardless of the housing, is set with the front rotor at TDC and the crankshaft's front keyway being at 9 o'clock. This is not something you want to fool with!!

B

I wish load was called out in those charts. I'm a bit confused looking at them. RPM we know but load can either be low at the bottom or high at the bottom. If load is low at the bottom, then the max advance timing under boost is over 40 and split is negative! If load is high at the bottom then that means 14+ degrees of advance at idle with 28 degrees of total advance up top. That makes more sense. I'd still love to know what each load point is in terms of kpa.

Let me see if I can ask this correctly:
For my setup (series 4 housings, series 5 N/A rotating assembly, Racing Beat pulley), where should I "zero" my timing on the pulley? Should I find a series 4 hub/pulley setup and set it to the factory mark, or should I set it to 0 degrees TDC on the Racing Beat pulley? I am using your timing map by the way. After reading through all this pulley and timing difference stuff between the series 4 and 5 housings, and considering a have an aftermarket RB pulley, I am a bit stumped. Can you help clarify this for me? I know my timing is definitely off, but I need to know where to exactly set it to.