[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Timing advance setting with Engine Management System
I'm not sure what to say.
Thanks??
Anyway, I'm glad for you!
Always nice to see someone that can take matters into their own hands ;^)
Dan
----- Original Message -----
From: "Jeff Toomasson" <area53@validpath.com>
> Not me. I got a woody! </boi-oi-oi-oing!> hahaha :D
>
>> good info dan.
>> now does anybody else have a headache after reading that much techinical
>> info
>>
>> On 5/3/05, Dan Bubb <jdbubb@ix.netcom.com> wrote:
>>>
>>> For full throttle I think what you have is pretty close.
>>> Full advance by 2500 seems a little fast to me, so I'd lower the value at
>>> 2440 somewhat.
>>>
>>> Couple general comments about spark timing and setting up load points on
>>> an aftermarket engine
>>> management just cause I can't help myself.
>>> 1. I don't think these engines need a huge amount of total advance at WOT
>>> based on input from both
>>> TT and NGP. I would think 32-34 max would be good. Plus you have a higher
>>> than normal compression
>>> ratio and that speeds up the burn rate meaning you need even less advance.
>>> 2. The burn rate in the combustion chamber varies with throttle opening.
>>> More throttle=higher
>>> density in the chamber=faster burn rate. So, at partial throttle (cruise
>>> conditions) you need to
>>> have more advance. So, you might try adding more advance in the lower load
>>> positions. As an example,
>>> if your engine cruises at .5 bar/15"vac then you probably want to have
>>> 12-15 deg more advance at
>>> that RPM point then you do at WOT for that RPM. In other words you want to
>>> emulate the vacuum
>>> advance of mechanical distributors.
>>> 3. Engines are generally linear in their requirement for fuel or ignition,
>>> but with some exceptions.
>>> One is around idle where some monkey business , mostly with the ignition
>>> timing, can improve idle
>>> quality especially if you have wild cams. The second is engines with wild
>>> cams tend to have weak low
>>> speed performance and at a certain RPM "come on the cam".
>>> The TEC II (and also Megasquirt) has 8 load and 8 RPM points. I would
>>> adjust the RPM points so you
>>> have a couple close to the idle speed, and several around the RPM where
>>> the cams kick in to handle
>>> the drastic change in fuel required there, of course one at your max RPM,
>>> and last one or two in
>>> between those points.
>>> For idle, one at the desired idle speed, then one RPM point a few hundred
>>> below that. This lets you
>>> put in the actual idle advance at the idle RPM and really bump up the
>>> advance if the idle should
>>> falter some. So, say 6 deg across all load points at 1000 RPM and 20 deg
>>> at all load points at 700
>>> RPM. Idle drops down, advance kicks in and helps to bump the idle back up.
>>> Let's say your cams kick in around 4000. If it's a big change in power
>>> then you may want an RPM
>>> point at 3700, one at 4000 and one at 4300. The ignition requirements
>>> don't change drastically when
>>> the cams come in (or maybe it just doesn't matter that much) but for good
>>> drivability the fuel will
>>> change quite a bit and that's why you need a bunch of RPM points around
>>> non-linear behaviour.
>>> Also, since you're running ITB,s I'd also bunch the load points towards
>>> the higher end of the range
>>> especially if your using MAP (manifold absolute pressure) for load. Maybe
>>> if you're running throttle
>>> position for load this would be less important.
>>>
>>> I'd put in an ignition map here but the formatting will be all hosed. So,
>>> if you'd like my idea of
>>> an ignition map LMK and I'll send you one in Excel.
>>>
>>> And one last comment. You are going to run more than 7000 RPM?? I bet your
>>> power peak will be that
>>> high and you need a few hundred RPM beyond that for maximum performance
>>> through the gears.
>>>
>>> Anyway, that's what I think. Most of this is based on experience with a
>>> 2.0L 8V with ITB's and a 306
>>> cam using Megasquirt running to 8000 RPM.
>>> Hope this is clear for all that read this far.
>>> Dan
>>>
>>> ----- Original Message -----
>>> >From: "Don Walter" <dswalterwi@gmail.com>
>>> >To: "Scirocco List" <scirocco-l@scirocco.org>
>>> >Sent: Monday, May 02, 2005 9:56 PM
>>> >Subject: Timing advance setting with Engine Management System
>>> >
>>>
>>> >Okay with the TEC 2 I can set an 8x8 grid for the Advance based on RPM
>>> and
>>> >MAP (manifold air pressure). I have a 16V 2.0L with Autotech Sport Cams
>>> and
>>> >have looked heavily throught the Bently on an idea how I should be
>>> setting
>>> >the advance table. As near as I can find the idle advance should be
>>> around 4
>>> >to 8 degrees with the full advance by 2500 rpm as 13 degrees mor than
>>> base.
>>> > Quote from Bently:
>>> >CIS-E rpm-dependent timing advance:
>>> >total timing @ 2500 rpm = measured base timing value (4 to 8 degrees
>>> BTDC)
>>> >plus approixmately 13 degrees
>>> > In the TEC 3 grid I have it set on average as:
>>> >12 degrees at 816 rpm
>>> >17 degrees at 1628 rpm
>>> >34 degrees at 2440 rpm
>>> >36 degrees at 3252 rpm
>>> >36 degrees at 4064 rpm
>>> >36 degrees at 4876 rpm
>>> >36 degrees at 5668 rpm
>>> >36 degrees at 7000 rpm
>>> > 36 degrees total I am thinking about turning down to 28 degrees total.
>>> > Does anyone have any input as to how they have theirs set?
>>>
>>> --
>>> Don Walter - Waukesha, WI
>>> 1986 2.0L 16V TEC 2 Black Scirocco (see progress at
>>> http://www.cardomain.com/memberpage/708939)
>>> 1986 2L 16V Toronado Red Scirocco (under repair)
>>> 1988 1.8 16V Toronado Red Scirocco (sold on 3/29/04)
>>> 1984 1.8 8V Pewter Scirocco (sold years ago)
>>> 1971 Karman Ghia (sold)
>>> 1969 Karman Ghia (sold)
>>> 1969 Beetle (sold)
>>>
>>> _______________________________________________
>>> Scirocco-l mailing list
>>> Scirocco-l@scirocco.org
>>> http://neubayern.net/mailman/listinfo/scirocco-l
>>>
>> _______________________________________________
>> Scirocco-l mailing list
>> Scirocco-l@scirocco.org
>> http://neubayern.net/mailman/listinfo/scirocco-l
>
>
>