BklynRX7

AS im sure you all know msd ignition boxes ahve to be set by cutting loops to perform for a v8, v6, or i4 engines. But what muts I set for a rotary? The guys at msd said the rotary performs like a 5 cylinder and to set it at either 4 ot 6 and just adjust my timing. Is this right? and exactly what must i do to the timing?

RETed

First, their built in rev limiters are next to useless when using the MSD only on the trailing.

Second, with that said, if you are just installing one on the leadings, it doesn't really matter - if anything, get a 6A (4 / 8-cylinder) or the Digitial-6.

Third, bitchslap the idiot who told you the rotary fires like a 5-cylinder...


-Ted

BklynRX7

First of all it was a MSD tech that told me that so that shows u how much they know about a rotary.

So your saying if im not gonna use the rev limiter, which i wouldnt, then i dont have to worry about these settings?

For the record im installign a 6AL on the leading(6420) and eventually a 6A(6200) on the trailing. Im only doing the leading for now.

YearsOfDecay

OK... lets clear some things up...

If you are not using the Rev limiter (which i highly sugest you DON"T) then you just disable it and hook up the wires.. All the box does is amplify the trigger signal and send a higher volatge to the coil... until the rev limiter kicks in.. then it will drop the spark at various intervals depending on what cyclder setting you have it on... The 6A's are complete dumb boxes... they take the input, amplify it and puke it out.. thats it, thats why there are no cylinder settings on those.

If you plan on putting a box on the trailings... you have to use TWO seperate boxes.. one for EACH trailing coil. You only need 1 box on the leading because it fires in a waste spark configuration (both coils fire at once, every time) The trailings are seperate and each have an individual trigger.

Now, if you want to use the reve limiter functions, you will need to put the SAME boxes on the leading and trailing and the SAME limiter pills in each box.... or you might not be having a good time when it kicks in!!!

This is why most people only put MSD'a on the leading.. only need one box. I've seen three boxes before, but they usually have all three mounted in one of the bins... thats a LOT of wire to run from the trigger lead to the box and then back to the coil..... I just don't trut it.. Keep your wiring as short as possible, thats what my old man always bashed into my skull!!!

If i had an extra 300 bux falling out my *** for two more MSD 6A's , i might try it (The haltech has a two stage rev limiter built into it.. no need for a 6AL)

ilike2eatricers

For the price of 3 MSD 6As you could just get an HKS Twin Power. TINY unit that does the leading and trailing. I have one and love it.

YearsOfDecay

good point as well!!!!

BklynRX7

I understand all that, i was neevr planning on using the rev limiter. I just misunderstood the instructions and missed the part sayign that the 6a (or the 6al without the limiter) doesnt haver to be set anyway.

AS for usign the same boxes i dotn think i would need to since the 6420 wouldnt be using a rev limiter it would be performing just as the 6200 is. RIGHT?

RETed

Ah, that explains it.
These are the same bitches that told us their DIS-4 could push the 13B ignition - NOT.


A 6AL is a waste of time.
Just get the bare-bones 6A with no rev limiter.


-Ted

BklynRX7

well since I already have the 6AL(real cheap) im just gonna use it and not insert the rmp module.

It will still work correctly right?

Same for having a 6420(6AL) on the Leading and a 6200(6A) on the trailing.

JamesWade2002

Sorry to bring this back up, but I just found it.
I don't trust the stock rev limiter as it seems to be ineffective. I have a 6AL and want the rev limiter to work. Is there anyway for it to work or even slow things down when its just on the leads? Which wire should I cut?

RotaryResurrection

iTrader: (8)

Dude, this was already explained.

IF you're using only one box for the leading, you can't do it. Because even if your leadings get cut at your limit, the trailings are still trucking right along and the engine will continue onward, though not as fast I would guess. It makes no sense to try it this way, though, and you might very well cause a bigger problem trying.

Besides...who wants to LOWER their rev limit? I assume you are using the stock ecu which has it's own limiter which can't be changed without a reprogram. The limit is in the ecu, not at the coils. So even if you put a higher rpm pill in your msd box, the ecu is still going to limit the input before the MSD, so you'll still hit that one first. So you cannot raise your current limiter, only attempt to lower it. Unless you get a knightsports chip or something that removes the rev limiter.

Maybe I just don't see the point?

JamesWade2002

anything to slow it down. The tach is going so fast in first gear and when I'm at an autocross it will bury it solidly at 8K in second before I get to the first corner. I am running S4 internals with adkins seals, so I really have no idea what a safe rev limit is for this motor. Anything to slow it down even after 7k. I don't think the stock limiter even works now. I just races right past 7500 and then stops at the bottom of 8000. Is it supposed to do that?

cool_as_crap

nvm il search

RotaryResurrection

iTrader: (8)

First, if you are making too much power ( ) then maybe you should slow it down by restricting intake/exhaust airflow. IF your complaint is about the gearing running out, swap in a 3.9 diff for longer gears.

The biggest thing to keep in mind is that factory tachs are almost never totally accurate, especially on older cars. This is the case with every 7 I have tested. The factory tach is usually a little "fast", meaning it might be showing 8 grand while the engine is actually only turning 7750. The amount it is off varies by car, though. Because of this, different car owners tend to think they have different rpm limiter points, but in reality their tachs are just off. A limiter around 8 grand is perfectly normal for an s4 car.

JamesWade2002

I'll test it again. obstructing flow of any kind is NOT an option and neither is higher gears. I really need an agressive spark limiting rev limiter that I know works all the time for cheap and easy. I Think Megasquirt will fix this as well as other stuff too. So what is the definative word on the limits of stock S4 internals? I would like to spin as high as I safely can, say 8500, as this would put me where I need to be on the track in 1st and 2nd gears.

RotaryResurrection

iTrader: (8)

8500 is doable for s4 internals, but I wouldnt recommend sustaining it for long. s5 setups are more suited to that. around 8500 is when you start to see shaft flex, the side tips of rotors contact the irons due to said flex, etc. especially with the heavier rotors.

so now your plan is to spin the engine *faster* than the stock rev limiter? man, I am real confused at what you're trying to do here. first you want to slow it down, now you want to rev longer.

as I said, swapping to a 3.9 diff would give you an extra 3-400rpm at the top of each gear to play with, with speed being the same. you can pick them up for nothing from auto owners doing swaps. if it's as big a deal as you talk like, it might be something to consider.

JamesWade2002

I'll just see where the stock limiter hits, if it hits. I need to be able to come into a corner on the limiter, because it takes longer to shift than it does just to sit on the limiter for a sec in some areas. I just don't want the motor doing 9,000 if I don't have time to shift and just keep my foot in it. The question about the limit of S4 stuff was directed more toward my mid summer plans of setting up a megasquirt with ignition control and a really agressive rev limiter, which I guess I'll set at 8,000. That way if I am in, say 2nd gear, and wanna just pin it to the limiter for the last few seconds before I brake for the corner, instead of trying to go for 3rd, which I might be in for like 1/40th of a second, I'll just bounce it. The 3.90 would work if I was always able to keep the engine above like 5,000, but there are places where I might have to go into a slow turn in 2nd, and I won't be able to hit 1st. I'll just have to exit a turn in 2nd at like 15mph, which is the slow way around for me anyway, then add the 3.90, and you see where I'm at. I need a rev limiter I can really abuse, something that cuts in above all the other noise and confusion of an autocross run and says "HEY, DAMN IT, YOUR ON THE LIMITER!" Its not a comfortable feeling when I look down and realize I have been thinking about the next corner, and I didn't notice the tach needle is bearied against 8K and I have no idea what speed the engine is really doing. Clearer yet....still mud? I'm tryin.

RotaryResurrection

iTrader: (8)

I can assure you that your stock s4 ecu will not let you rev past 8500. So 9 grand is not a concern. For what you are describing, it should be okay left alone...but if you run it every weekend, well, that engine might not hold up for more than a year or 2 like that. IF it's a once every month thing, I wouldnt give it a second thought.

IF you want to check for a limiter, warm it up and hold it WOT in neutral...wait just long enough to hear the stutter, then let off. Your factory tach will probably show it anywhere from 7800-8200, but the ecu is seeing a more accurate tach signal than you are...I have never actually hooked up a test tach to find out the exact rpm that the ecu limits at, but it is there...or at least it is on every car I've tested.

See, if you just had a FD and a PFC, you could adjust your rev limit anytime you wanted with the touch of a button.

JamesWade2002

If I had an FD......oh man....those helmet humps in roof....those awsome tiny coils....FDs makes me happy.

Dom_C

I don't agree, with the rev limiter in nutral(sp) On a s4 na block with s5 rotating assembly and a monster 6 port to 4 port conversion it would rev way past 8500 in nutreul, I feel like this is because of the ecu only cuttin gfuel to one rotor and the other being able to take it past there while in nutreul with very very low load. ANd to clear it up, the actual rev limiter on that car was at 8500 stock, this is varified by the dyno tac, the stock was only reading 7800. This isn't saying that some cars may be freaks of nature but I imagine mazda made all ecu's the same with little margain of era. BTW kevin, you built this engine. I was not the one to rev the car in nutreul way past 8500, that would be the stuid *** redneck that I sold it too, he loved it just because it sounded like a chain saw. . he told me that and I just looked at him in aww wondering how stupid one could be.

RETed

Don't take this the wrong way (but you probably will)...
...but learn how to drive.

I've got no problem shifting from 1st to 2nd just by watching the STOCK TACH with my peripheral vision.
Once I see the tach needle go vertical, I do a quick mental split-second countdown, and I can shift consistently at 6,500RPM (for drag racing).

If you don't like watching the stock tach, get one of those "monster" aftermarket tachs.
Mount it higher to help with your vision.

If you can't keep track of the stock gauges and on the race course, I dunno what you're doing there in the first place?

There is a write-up buried in here that uses a single MSD 6AL (or equivalent) and an RPM switch to cut POWER to the trailings.
This effectively gives you an adjustable rev limiter, BUT you're still allowing raw fuel to get into the engine.
And ignition cut like this makes for some violent backfires that can damage things!

If you want to get serious, get a stand-alone and then adjust the rev limiter to where ever you want!
If you're banging off the rev limiter all the time on the race course, that kills you time and upsetting the chassis, so this is not even a very good fix for your problem.


-Ted

JamesWade2002

um....don't take this the wrong way but, how many autocrosses have you been to? What would you do to fix the problem of running out of revs just slightly before track? Why does everyone on here think that everyone at an autocross race has to posess the same skills as a drag racer or a open coarse road racer? There is simply no time for even glancing at the tack when you are in the middle of a slallom and the chassis is VERY upset, your very loose one second, then on entrance to the next set of cones 1/30th of a second later your front wheel's slip angles are just off from what they need to be to make inside the cones, this all takes tremendous concentration(while you are doing this you are stareing at the front inside corner of the next cone, not your tach). I went to the drag strip and never missed a shift at exactly 8k on every run all night long. On a large race course, there is lots of time. Let me say that again TED, THERE IS LOTS OF TIME TO LET THE CHASSIS TAKE A SET. If you take a streetported S4 out to an autrocross that is open and revs fast, you will rev it straight up into the rev limiter, if it has one, and you will never see it or feel it or have a chance to fix the situation, it will just be how the coarse is laid out, and it will happen over and over again. The guys who have been doing this for years do this. The guys that go to Topeka EVERY year and have Corvettes that are almost as fast F125s are throwing fire out the pipes and the cars are cutting out hard as they aproach some corners because there is no time to shift and they won't lift. If the stock fuel cut really does come in at somewhere near 8k then I am happy with that, if I can verify that it works. I just don't wanna autocross this car all season and then have 80 lbs of compression at the end because the STOCK S4 ecu couldn't control things.

RETed

I was doing SCCA Solo II down here in Hawaii a LONG time ago, but this was before I was into FC's.
You're right - people bang the rev limiter all the time on the track; I would still try and avoid it if possible.
You can still play with the gearing or tire size, unless your class doesn't allow you to do so?

You're right - depending on the course layout, you can run into a transition where you need to choose to either bang off the rev limiter or upshift and lose precious fractions of seconds.
I question why you're pushing so hard in a local event?
If we're talking about regionals or higher, why are you asking us for advice???


-Ted