TDIT

Hi all,

Does anyone have a 20B timing map for an NA non-PP engine? If so, can anyone post a screen shot please? It would greatly help me out.

Many thanks!

bumpstart

you mean a non turbo 20b PP NA engine?

same as the other PP's

mechanical curve starting somewhere i expect about 15 -18 BTDC .. motor depending..to keep it happy at idle

and maxing out around 22-26 degrees.. motor depending.. at peak TQ revs

after that adding 1 degree for every 2000 rpm past peak TQ revs

( i.e// if peak TQ is 6000.. it will be say 25 at 6000..26 at 8000, 27 at 10000 etc )

vac timing i would leave flat if the motor pulses lots at steady revs

but i expect it pulls only about 10 inch Hg
and if the signal is not choppy
( you can use a little fuel filter in the vacuum//boost line and a oneway valve in the brake booster to try and even it up )
and you could try and spread up to 5 degrees vac advance into that 10 inch vacuum scale

though for first time tuners it may be better to leave that a little flat for now and concentrate on maximising power at each rev on the mech curve

TDIT

Thanks for the reply mate.

No turbo and no PP

Just a naturally aspirated 20B without peripheral porting.

Does not being a PP change your advice?

Many thanks!

bumpstart

the less it is ported then the lower the base timing and the wider the vac advance spread will be
and generally the max timing is determined by the amount of Hp you would expect

as a rule the s5 turbo engine with same rotors makes around 100 hp per rotor at 9 pounds of boost
.. its timing will be around 25 BTDC at zero boost
and will have pulled 5 -7 degrees out when at full boost at that HP
.. ie 100 HP per rotor is 18 - 20 BTDC with 9.0 :1 compression
.. and a stock ported engine needs 9 pounds boost to make that airflow




for a stock to mild port non turbo engine with 9.0 rotors
and expecting around 75 Hp per rotor at zero boost

then timing would be 25-28 BTDC at pk tq revs
and the same 1 degree rule for increasing the timing every 2000 rpm after and above that point

a stock engine idles mostly at ( -5 ) 5 ATDC to ( zero ) TDC

and a mild port engine will like somewhere from TDC ( zero ) to ( +5 ) 5 BTDC as idle base timing

both will like you to have got to at least 20 degrees by 2500 rpm
on its way to that 25- 28 BTDC pk TQ max value somewhere from 4500 and 6000 rpm at the engines sweet spot

the vac advance of a stock or mild engine will be spread over double the range of a PP
...from 20 inch Hg to zero vac
the vac assisted timing will be much as 8 degrees spread over that range
( ie 8 degrees at 20 inch Hg and zero at zero inch Hg )

bumpstart

PS.. if you want you can take a hint from the FSM for the s2 rx7 where it describes the graphing of the dizzy and its vac pots in some detail

be aware that the description for mechanical rpm mapping is out of context displayed in dizzy degrees and effectively all the numbers for the mech timing double to relate as crank degrees

when you map it out
you will see most dizzies ( for 9.4:1 compression engines )
will time for 5 ATDC or zero and max out somewhere in the 22-27 BTDC region
with a supplementary 6-10 degrees vac advance

for the 9.0 rotors it is natural to shift the base timing more advanced slightly to maintain the idle quality the same
and push just a little further in pk timing

t-von

iTrader: (8)

Nice info! Now I'm just trying to visualize the timming curve. Would the formula be much different with 9.7 rotors?

diabolical1

iTrader: (3)

this is great information. Bumpstart, thank you.

bumpstart

9.7 rotors will bring down the pk tq max timing value by a few degrees

and may also allow you to be a little more conservative in the idle/ base timing value to keep the same idle vac and quality

without the turbo you have a little margin to get things not so right and you can play things up or down a little on the road for max response without necessarily needing the knock ears and a dyno


having too much timing on an NA will mostly cost peak power
and may push the car to mild detonation on hot days and even cold mornings or when loaded up with weight going uphill

so if road tuning definitely listen hard, watch your wideband closely
and keep a sensitive foot on the accelerator feeling for the little kicks that tell you all is not well

if that happens get off it, pull up to 2 degrees max timing and let the engine idle or coast down for several minutes to relieve the internal temps that have built up on the rotor


for the split timing then generally at idle it is 15 .. at part load it bunches up tighter to 8 to 10 degrees and at WOT it goes back to full width 15
at higher revs than what you will see it may pay to bring the timing closer again . but leave that for the PP guys

t-von

iTrader: (8)

^ Really thx for this. You can go ahead and post the PP info. This info is really great for the forum as a base to help get started.

TDIT

Thanks Bump REALLY appreciate your help with this. I already am starting to understand where the tuner went wrong with my 20b. I have an afr of 14's but my emissions are 3 times the legal even on e85 with new very high density cats in series. So I figured I HAD to have an unburnt fuel issue. looking at your comments and making notes, it's clear the timing I have can be improved greatly. I will make up a map and post for consideration.

Cheers and thanks again

t-von

iTrader: (8)

Curious, why E85 on an NA rotary? Are you running your air pump? Also did your exhaust smell of unburned fuel with those cats in place even though you had hi readings?

bumpstart

i expect he is putting the turbo on later or is cleaning up his NA part of the map


lots more to it i am afraid, as a 20b isnt easy on an IM240 test even with all the tricks

you need to tell us what type of ecu it is for a kicker and then the manifold and injector setup

it isnt a matter of getting it lean enough on e85
... you may need an electric air pump and do need a quality cat placed in a sweet spot for temp

you will most likely need to first play the start of injection ( or end of injection, ecu depending )
injection angle timing up and down on the current fuel tables
till you see the richest AFR at each of the rev plots

then you go back and trim up the fuel map

TDIT

trying to get it passed emissions. failed with turbo and e85. no secondaries during test. rev limited to 5k. tune was done on dyno. great for turbo, bad for emissions.

turbo bypassed. direct air intake now in place. thought timing was too low. is actually too high. in mid 30's bu 3k rpm.

cat's are two euro5's but connected and in series. very high density brick style.

no air pump - that's next on the list if I can't get it over the line with na and different timing.

oh - intake restrictor is now also in place. down to 45mm opening.

timing advice welcome.

computer is wolf v550. fully adjustable. suspect my issue was timing to advanced. time will tell.

cheers

bumpstart

be aware that some ecus do not allow a negative ( ADTC ) number to be used when setting up the datum point for timing

a microtech is a good example.. wolf i am unsure about

when faced with that , knowing timing mark on FC engines is 5ATDC ( -5 )
then the microtech preferred method is to consider the 5 ATDC mark as a zero
( as you cant tell the ecu consider it as -5 )
as such.. a microtech that thinks zero is negative 5
( or put another way is timed to the 5 ATDC mark )
will have a 30 in its load map .. that when measured with a timing light .. will actually be a REAL 25 BTDC

ie.. -5 + 30 = 25 BTDC


capiche?

if the wolf is setup the same then mid 30's is really only 30 degree !


the same issue,, but in reverse can rear its ugly head when a tuner grabs numbers out of a microtech

and duly punches them in on an ECU that IS already timed correctly in real degrees
( ie.. 0 + 30 = 30 real BTDC degrees )



what you must do,, and it is most important.. is figure out how this ECU was initially setup
either the 35 you see in the map equates to 30 ,, indicating they called the -5 mark a zero datum

or the 35 in your map is a real 35 at the crank
indicating they stole numbers out of a microtech and thus everything is 5 degrees too advanced

the best way is to mark the pulley for a 10 BTDC mark
on s4/5 and 20b pulley,, it should already have 5 and 20 ATDC marks.. 15 split
set and fix a set of dividers or calipers so one point is at 20 and the other is at 5

project this fixed gap forward clockwise from the 5 ATDC mark and make a new mark

this is 10 BTDC

( -5 + 15 = 10 )

using the timing lock function on most ecus, setfixed timing 10 BTDC
( all ecus will allow a positive timing lock number and all types of engine port will idle at 10 BTDC )

use the timing light and turn the CAS at the base ( or adjust trigger angle number in timing setup in ecu )
till your timing light and the new 10 BTDC mark are in agreeance

lock down the CAS and turn off the timing lock feature

your ECU is now timed to REAL degrees,, and what happens in the table,,more or less happens at the crank
( to some degree,, as there is drift in the reluctor timing signal translation with revs and good ecus allow you to factor that out )

as such,, you can now use the numbers you see in others maps more directly

// to pass ems you will need an electric air pump
as it has a high rate of flow at idle speeds and wont diminish if you turn down the revs
though you may need to setup the ACV so it pump into the exhaust ports and less post the cat

and to pass ems you absolutely need to optimise that angle of injection map

follow the hint i gave you ,, adjust the angle up and down till you see richest AFR, indication the timing of the injection is getting more fuel into the chamber and less on the walls

absolutely this is a neglected area in most ecus where economy and ems are to be optimised
i highly doubt the current map seen in the wolf ecu is anything close

TDIT

Okay, that's an awesome response Thank you.

The wolf can support negatives, though none are in place. I think the answer is it has been taken into account, as all the timing maps show a good idle at 11-12d passed dc. So I have to subract 5 from everything to get the real reading...

bumpstart

dont guess,, double check !

.. if you make the 10 BTDC mark and use that value in your timing lock then you cannot go wrong

TDIT

Shall do. All good =]

BTW, wolf does also support timing lock of X

Rub20B

What emission test do you need to pass and which emissions did you fail on (HC CO NOx?)? standing idling or driving on a dyno or? Cats only work well (at least for converting CO/HC and NOx) when afr entering is very near to lambda 1. so ideally you must adjust your timing in a way the engine will not misfire and run happy at lambda 1 in the speed/loadpoints which are used during the test.

If the mixture is rich, there is no oxygen for the cat to burn the CO/HC emissions unless you add secondary air with an airpump.

TDIT

Hi Rub

The beasty was too high on co emissions despite being at mid 14's for afr. The test is on a dyno which simulates typical street driving and low load. Car was driven to the test site (30 minutes of highway before), then left ideling until test. The test is run twice (without pause) and the better results of the two is the one that counts. Unfortunately mine were both shithouse - even on e85. The mob that did the tune (after my safe approximations) say the tune is fine - which logic tells me is not the case. Anyway, they are both out of business and being chased by creditors (I'm finding that rather amusing - especially since they provided a written guarantee that the car would able to pass emissions.) Did they screw only me? Narr, they over sold their abilities to several people. How rare right...?

Anyway, the history is just that. I'm finishing it off.

Now, this is where I'd like to say the problem's been resolved - but it hasn't. I'd like to say I'm working on it, but I'm not. Seems we have a little problem... The ecu was taken out of the car for safe keeping - and kinda put in too safe a spot. Yep, I've misplaced it. Will update when it's found... Oh I can hear the laughter already...

j9fd3s

iTrader: (3)

we have the same test, or very nearly in California, unfortunately we also have a visual inspection, and so we're required to run the stock emissions a equipment. anyways, i've managed to learn a few things in the 25 years i've been smogging these things...

our test is steady state, one an 15mph and the second at 25mph. for both tests the stock ecu is in closed loop, so its using the o2 sensor to correct to 14.7:1 AFR. the wrinkle is that for the 15mph test, the ecu usually is using "port air", the air pump air*. this means the net AFR at the cat is 14.7, but the engine is a little richer.

just generally the cats seem to like to be a little rich vs a little lean. take some time and really get the test spots and everything around them consistent, as rich spots obviously will give high co and hc, and lean spots can misfire which is also high hc.

we are required to run the stock ecu, and thus stock timing, but advancing the timing -10 degrees increased NOX, but HC and CO didn't move much.

if you can fit an air pump, it makes a huge difference


*i built a little tester and hooked into the diagnostic ports, so i was able to watch it being in closed loop and port air

t-von

iTrader: (8)

^ Yep gotta have the air pump. I can run fairly close to stotch without it but you can smell the exhaust more. Engaging the pump cleans things up very fast. I have mine feeding the engine at idle and at 1,500rpms my solenoid opens to feed the cat.

TDIT

I will be honest, I've not tried an air pump (and yes, still have the stock.) But the problem for me is there's no room to mount it in the bay.

While the search for the computer continues, I have been doing some re-routing works. Turbo, disconnected - though still physically bolted to the car - and now there is a nice pod filter on the piping before the throttle body. The greatest benefit is allowing for NA tuning and timing. Rev limit is still set at 5k also. So the ranges for a nice tune are there and not difficult to put in place with a mate behind the wheel on the highway as I tune. But one needs a computer - (Charlie brown *sigh* moment.)

Does anyone know if there is a smaller airpump available that will fit? Failing that, and I'm not kidding when I say this) I have a mate that deep sea dives and he's told me I can borrow a small tank and regulator. Once said, I'd rather just find a pump that worked and do it once then forget about it.

Thanks to *everyone* that's commented. Once I find the ecu there will be a lot of work to do.

Rub20B

Yeah I think the main problem is with rich mixture the cat has no oxigen to convert the HC and CO, if the engine runs lean there might be oxygen but not enough temperature or HC CO to burn and the cat might not fully light off. so slightly rich engine out mixture with high CO HC and then secondary air from the pump will make for a happy cat =)

TDIT

Agreed. Though finding a pump is proving tricky. Of course finding the ecu is a little more important.

Another option open to me is e99. I can get a 200 litre drum of it for around $380. If it solves my hydro carbon and CO problem, it will be worth it. It should address both...

The other 'problem' I have is I'm running premix at 1:100. That oil doesn't burn clean, but I can;t run without it unless I out the car on a trailer and toe it to the inspection site. A 45 minute drive without lubrication is not something I am willing to risk on an engine of this calibre and cost.

j9fd3s

iTrader: (3)

the Rx8 electric air pump is pretty small, pretty much every 2000's car has an electric airpump on it. not sure they would last long term, but any of them should work for the test