timing maps/strategies for old-school turbo engines

[thechuckster]

hi folks,

Wilbo and I did some tuning of the 18RTE last night -- and it gets on boost so goddam easily now ...

Much of his work consisted of pulling out fuel from my initial VE map and learning how to drive the tuning software while i avoided hitting things driving up and down Mt Cootha. So +ve to him for being a quick learner while under seige

However, afterwards we were still guessing as to a good reference point (and a tuning strategy) for improving the timing map.

When i get home, i'll post a pic of the current map (and our fueling efforts to date) but i'm curious if anyone could point us towards any ignition timing resources.

As the engine old-skool (non-cross flow, SOHC, iron head, tapering combustion chamber) and forced induction (ex-RB20 turbo) i can only use existing data on 18Rx engines up to 0psi boost.

Will's borrowed a copy of Corky Bell's book, but anything else on timing maps would be handy.

Anyone with an 18RG turbo willing to share their timing maps?

tia,
Charles.

[Hen]

Some stuff I stumbled across a fair while ago:

General ideas for setting up timing

And about dyno tuning a turbo 20R. Short, but maybe useful.

Both pinched from this page

Good luck
Hen

[VeeP]

hey man, just a quick question

what did u find was the best fuelling setup early in the RPM range in order to bring the turbo onto boost quickly. ie over fuelling, under fuelling etc ??(considering the only change to timing i can make is the base timing figure)

[thechuckster]

Hen: thanks for that, i remember reading up on SDS hardware ages ago... but once i found msefi, it got left behind.

VeeP: we were tuning for near or just under stoich when off boost - too much fuel when not on boost makes the engine miss and cough, not enough fuel makes it surge.

The accel enrichment prevents the engine stumbling as you suddenly go from high to low vacuum (e.g. accel). And that's something we're still trying to get right.

Given that you have a factory ECU, the only things i'd suggest you tinker with are FMIC, piping, zorst and a cooler air inlet. Playing around with base timing is risky.


Anyway - timing and fuel maps - (100kpa is 0psi):

Timing

Fuel


If it helps you to visualise stuff, here's those two tables as 3D wire charts:
Timing

Fuel


FOr those with megatune, see attached MSQ file - it's MS/Extra_HR_09c code so you may need to down the firmware from here (zip file).

[30psi 4agte]

Chuck:Just looking at your ignition map. Im used to a slightly different setup so my Q is :

I assume the 200 kpa mark 14.7 psi of boost if 100 kpa is 0 psi ?

I take it is like this because the ecu takes into account atmospheric pressure.

[thechuckster]

yup - kPa is an absolute measurement

0kpa=absolute vacuum, ~100kpa = atmospheric (14.6psi), 200 = 14.6 psi of boost, etc

[30psi 4agte]

cool...... thought so

The ign map looks pretty good. It may be retarding a little early as the boost come on but like you have stated it is an older setup.

Is it going to go on the dyno for a propper tune ? Or are you guys just gonna have a play for now and try to sort majority of it yourselves ?

[thechuckster]

plan was to sort out most of the tune with road use - then polish it on a dyno and some logging of drag/track runs.

I've got a wideband sensor making road tuning a little easier.. plus some of the extra features in the ECU are yet to be turned on (e.g. idle timing map, PWM idle control, AFR target table & boost control) and it would be a waste of dyno time to work them out at a workshop.

Big upside of this is learning part.

[30psi 4agte]

I agree with there.
the more you can do yourself the better before the dyno. It gives you time to sort out all the little bugs so that when it comes time for the tune on the rollers all they have to do is tune and not fart arse around sorting the little things.

[thechuckster]

... plus i'm going to ues a dyno shop that lets me help with the tune and a shop that wants to learn about a different kind of ECU. Mr DOHC and MonkeyMajik have given me names of shops that would be interested in seeing/playing with a Msefi ECU.

[30psi 4agte]

I dont blame you ! I did the same thing when my car was tuned.

I like to be a part of stuff. Its not that the tuner isnt any good but more of a ........ Its my car and i know it better than anyone sort of thing.
So if something is a miss i like a tuner that will listen to what i have to say + bounce ideas off of. Not one that thinks he knows better and tunes the car the way he wants insted of the way i want.

[chris davey]

You are in luck Charles. I just got all my data off the microtech last night. Obviously not the same setup but it may help. I will whack it up here in a few hours.

Can you get a log with rpm, MAP and AFR? What wideband do you have again?

[thechuckster]

Chris: I now have an LC1 hooked up to the ECU, provides linear AFR readings from 10:1 to 20:1 ... is very helpful :-) ... i'll do a drive tonight with O2 correction off and post a log.

I have copies of some timing maps you posted a while ago - they were helpful!

I can even post the XLS file of entire datalog and anyone with Megalogviewer (a free log analysis/graphing tool for Msefi users) will be able to review all the engine data i'm collecting.

30psi: yeah, i figured i'd have to spend 2 hours telling the workshop how i setup the car and what the various quirks of the car are and then another 2 hours listening to someone tell me all about what i did wrong (which i already know)...

I rarely take the car to workshops so i prefer to use someone who can work collaboratively with me ... plus a tuning shop that takes a liking to Msefi could announce its services to other Msefi users in BNE (of which there is a growing population).

Whether they'd want to participate in the forums and free sharing of information/experiences is another thing ... but helping the community invariably results in work coming your way.

[chris davey]

Here is my current map. 1jz-gte, Hypergear TR44, running 15psi presently. This has been used with my old Ta45s at 17psi and spiked to 22psi IIRC. Engine still runs

I am working on some changes mainly adding about 4 to 5 deg to the less than 4000rpm and vacuum areas. I got the base map for MT 1jz and it uses a lot more timing than I have so I thought I would give it a go. I use a jaycar super ear kit (thanks Charles) and a knocksense.

[oldcorollas]

Chuckster, how fast do you find the response of the LC1?