timing curve(s) for 18RTE

[thechuckster]

hi folks,

am having difficulty trying to guess out a starting timing map for the turbo 18R.

The original setup ran a modified dizzi but i can't find any notes on my actual install.

Some of my paperwork from that part of my history (a Street machine article about Mike Vine turbo kits on old holden 186/202s) has this advice:
-static timing liming to 24 degrees
-mechanical advance starts at 2750
-total mechanical advance of just 6 degrees
-limit of 36 degrees overall advance
-anything with over 4psi requires water injection (which i had)
-anything over 9psi requires advance to be retarded (which i didn't have - dammit)

Unfortunately, going thru the megaquirt site looking for 8-valve turbo setups provided a confusing example:
2.6 mitsu, 10spi turbo, base timing of 9-10 degrees with advance curve ending up at ~50 for high vacuum and around the 40 degree mark when at maximum boost.

Going thru here provides the a confusing 2tgte map with also has low static timing with high boost-level timing. I also found some data from Chris Davey's setup (1JZ) which has wide ranging and high static timing (15-25 degrees from memory) and obvious boost retard pulling maximum timing from 35 down to 24 degrees.

The engine is:
2000cc / 7.4:1 comp / 375cc injectors (4AGZE) / 7-10psi max boost / estimated power is ~100 flywheel Kw

Suggestions for static timing and max advance across a MAP range of 0 to 180 absolute Kpa would be most welcome.

tia,
Charles.

[chris davey]

I am definitely no expert but couldn't you start with stock timing that the 18r runs and then just retard it once it starts to make boost. This is the suggestion a guy from microtech gave last week for a 3sgte.

2psi 28
4psi 26
8psi 22
10psi 20
12psi 18
14psi 16
16psi 15
18psi. 12

That was suggested to start with. So if you tried something like that to start with and then you can borrow my knock sensor if you want to check for knock and advance it a little at a time

Otherwise, pm Phil and see if he got in touch with Peter Kip on Saturday. I can't remember if he did. He runs an 18rg turbo and run 9.96 in a ke20. I am sure he knows a thing or 2 about these engines in particular. Otherwise, I can ask my fiance's dad as he knew him a little while back

[Mr DOHC]

unfortunately i didnt get in contact with him, but cliff/simon/alex all know him, but cliff/alex run 18RG Turbos, ask them at the next meet, or i can give u their mobiles if needed

[30psi 4agte]

I need more info!
What sort of ecu? ( is it a mega squirt )
How does it map I.E rpm and manifold pressure or just manifold pressure?

[thechuckster]

thanks for the interest - i will spread the +rep around

Megasquirt ECU - running MSnS-Extra
timing and fuel maps are 12 x 12, MAP versus RPM.
the fuel maps is VE, the timing map is degrees
(note: MAP is expressed as Kpa from 0-255, 21psi is maximum boost allowed by map sensor)

[thechuckster]

even if 18RG folks could just list the timing at idle and the max advance (and at what rpm) it would help with some guestimation.

[30psi 4agte]

Not sure how a MS is configured but the EMS has a -50kpa 0 kpa +50 kpa map range.( these are all sep ie -50kpa 0 - 12500 rpm etc) all of these are Vs RPM.

I use an EMS ecu and my timing is as follows


15deg across the KPa range for the first 1000 rpm This helps on starting the engine.
on the -50kpa map it advances to 20 at 1500 and then gradual up to 4000rpm where it holds 35 deg to redline


The 0 kpa map is similar but slightly lower timing across the board ( cos of more load )
The + 50 ( boost map is the same as the 0 untill about 5800 where it starts to retard about 5 deg in total.

[oldcorollas]

MS you can choose rpm vertices in 100rpm(?) steps, or manifold pressure in 1kpa steps, so the points can be bunched where you need them. ie, you get to choose any 12 positions for the rpm and MAP, to make 144 tuning points.

[scootaphill]

i think this may be part of what you are looking for

http://www.toymods.net/forums/showthread.php?t=4080

and good luck

cheers

[chris_rg]

even if 18RG folks could just list the timing at idle and the max advance (and at what rpm) it would help with some guestimation.

my N/A 18rge is something like 15 degrees at idle, 33 by about 3000rpm at full load all the way up to 7500rpm. I think i have decreased it slightly at higher rpm under full load.

goes up to 40+ under high vacuum and high revs.

my ignition tuning was pretty much a guess, except for full load where i listened for pinging and backed it off a bit.

here is some pics... i'm not using all the possible resolution, no need for it really.




not sure how much help this will be though

i imagine that the 18r will be a different beast altogether. Having a different combustion chamber design with different spark and valve locations etc.

cheers
Chris

[thechuckster]

I'm going to try these as a starting point - the ignition map is a best guess based partly on Chris's table and the fuel map is from a 2.6 mitsu turbo.

Spark Map


Spark 3D graph


Fuel Map


Fuel 3D graph


a few things to think about:
the car needs a lot of advance at idle as the CR is 7.4:1
i expect boost to come on strongly from 2800rpm
boost will initially by sub 10psi, but the engine has coped with 13-14psi previously
FPR is a rising rate

cheers and thanks to all - ill advise if the maps are anywhere near useful.

cheers,
Charles.

[chris_rg]

hi charles,

Just wondering why you have a rising rate FPR? is it because your injectors are close to their limit?

does the rising rate FPR add extra non-linearities to the fuel delivery?

cheers
chris

[wilbo666]

hi charles,

Just wondering why you have a rising rate FPR? is it because your injectors are close to their limit?

does the rising rate FPR add extra non-linearities to the fuel delivery?

cheers
chris

Most turbo cars have a RRFRP. When you are on 15psi boost the fuel rail pressure only appears to be 40psi - 15psi = 25psi! So if you up the Fuel rail pressure 1:1 with the boost (what most stock turbo cars do) then the fuel pressure remains constant relative to the manifold pressure.

It removes a non-linearity from the system

Cheers
Wilbo

[thechuckster]

just to add to wilbo's response
- at high levels of boost (if i get it there) the injectors are far from 100% duty (safety factor)
- it was the FPR as suggested by the supplier (name eludes me - have details at home)
- i wanted to be able to run uber-rich on boost
- it's bolted to the firewall now and i'm not real keen on replacing at the moment :-)

cheers,
Charles.

[chris davey]

No idea how the MS fuel map works but the ignition map looks pretty good to me. I was initially thinking that 15deg at idle is quite a bit until I read on. I think 19deg advance will probably be ok considering 10psi boost and 7.4:1 CR but I would still probably start a little lower like 15deg just to be sure. As from what I have read it is better to be retarded than advanced too much. And apparently you can go to the special olympics as well!