TwinSpark MegaSquirt conversion - Page 2 - Alfa Romeo Bulletin Board & Forums

Reply
 
LinkBack Thread Tools Display Modes
post #16 of 99 (permalink) Old 02-18-2012, 11:57 AM
Registered User
 
Grant's Avatar
 
Join Date: May 2004
Location: San Jose, California
Posts: 3,771
Send a message via AIM to Grant
You know, I'm actually having trouble finding the contradiction in what I said vs that. Can someone point it out for me?

1987 Milano Platinum - check for many new items. [B][COLOR="Red"]
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
[/COLOR][/B]

1989 Verde - Harsh shocks and SS rears, 27mm torsion bars, stainless lines, pads, 16X7.5 rims, 4.10 rebuilt platinum tranny, poly bushes, and RSR 28mm front and 25.4mm adjustable sways!

1984 GTV-6 - 80K miles
Grant is offline  
Sponsored Links
Advertisement
 
post #17 of 99 (permalink) Old 02-18-2012, 04:09 PM
Richard Jemison
Platinum Subscriber
 
Alfar7's Avatar
 
Join Date: Apr 2005
Location: Pensacola, Fl. U.S.A.
Posts: 5,777
Quote:
"When VVT is off (the cam retards back to the normal position) the intake valve opens later, and CLOSES later too.
Hint
earlier


Quote:
At high rpm, you want to turn VVT off because the intake valve closing time is retarded as well. At high pistons speeds (high rpm) the intake charge "lags" a bit and can't follow the piston as well as lower rpm. Because of this it is beneficial for power to leave the intake valve open later, allowing more of the charge to keep coming in, even thought the piston is on its way back up at the start of the compression stroke.
Just totally incorrect!

Richard Jemison
RJR Racing

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

"When you are dead you don`t know it.
Only those around you are distressed.
Same with stupid"
Alfar7 is offline  
post #18 of 99 (permalink) Old 02-18-2012, 04:12 PM
Registered User
 
Grant's Avatar
 
Join Date: May 2004
Location: San Jose, California
Posts: 3,771
Send a message via AIM to Grant
I think the issue is I'm talking about the intake cam and I think you are talking about the exhaust cam. Which brings up a point, VVT on the alfa is on the intake cam right?? haha.

On my car, when VVT is on, intake cam advances 30 crank degrees and opens the intake valves earlier, and closes it earlier too. When VVT is off, the intake cam retards, the intake valves open and close later as well.

1987 Milano Platinum - check for many new items. [B][COLOR="Red"]
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
[/COLOR][/B]

1989 Verde - Harsh shocks and SS rears, 27mm torsion bars, stainless lines, pads, 16X7.5 rims, 4.10 rebuilt platinum tranny, poly bushes, and RSR 28mm front and 25.4mm adjustable sways!

1984 GTV-6 - 80K miles

Last edited by Grant; 02-18-2012 at 04:15 PM.
Grant is offline  
 
post #19 of 99 (permalink) Old 02-18-2012, 04:24 PM
Registered User
 
Grant's Avatar
 
Join Date: May 2004
Location: San Jose, California
Posts: 3,771
Send a message via AIM to Grant
Anyways, I might not be correct ultimately about why VVT should be turned off eventually on a 4ag, but I have dyno charts to prove that it is beneficial to turn it off a few thousand before redline. I don't want to digress anymore though, as you probably have experience showing losses by turning VVT off within the rpm range that a Nord typically sees, and that's all that is important on this forum!

1987 Milano Platinum - check for many new items. [B][COLOR="Red"]
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
[/COLOR][/B]

1989 Verde - Harsh shocks and SS rears, 27mm torsion bars, stainless lines, pads, 16X7.5 rims, 4.10 rebuilt platinum tranny, poly bushes, and RSR 28mm front and 25.4mm adjustable sways!

1984 GTV-6 - 80K miles
Grant is offline  
post #20 of 99 (permalink) Old 02-19-2012, 06:12 AM
Richard Jemison
Platinum Subscriber
 
Alfar7's Avatar
 
Join Date: Apr 2005
Location: Pensacola, Fl. U.S.A.
Posts: 5,777
Misinformation

I don`t believe you can read

Quote:
I think the issue is I'm talking about the intake cam and I think you are talking about the exhaust cam. Which brings up a point, VVT on the alfa is on the intake cam right?? haha.

On my car, when VVT is on, intake cam advances 30 crank degrees and opens the intake valves earlier, and closes it earlier too. When VVT is off, the intake cam retards, the intake valves open and close later as well.
__________________

I suppose Toyota has found a way to change duration on the cam?? Not! And I can`t imagine advancing a cam 30 degrees (crank) as Alfa`s are 6 degrees at the cam and 12 degrees at the crank. My Acura NSX has VVT on all four cams and they are not more than the Alfa`s

Read my post:

Quote:
Quote:
"When VVT is off (the cam retards back to the normal position) the intake valve opens later, and CLOSES later too.

Hint
earlier
Quote:
and CLOSES later too.
I explained all this in detail, If the valve opens later (vvt non advanced) the valve closes earlier (function of duration)

With the VVT on, the valve opens earlier and closes later

We are only talking intake cam Nit Wit, haha

Richard Jemison
RJR Racing

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

"When you are dead you don`t know it.
Only those around you are distressed.
Same with stupid"

Last edited by Alfar7; 02-19-2012 at 06:23 AM.
Alfar7 is offline  
post #21 of 99 (permalink) Old 02-19-2012, 12:01 PM
Registered User
 
Grant's Avatar
 
Join Date: May 2004
Location: San Jose, California
Posts: 3,771
Send a message via AIM to Grant
haha so funny Richard.

1987 Milano Platinum - check for many new items. [B][COLOR="Red"]
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
[/COLOR][/B]

1989 Verde - Harsh shocks and SS rears, 27mm torsion bars, stainless lines, pads, 16X7.5 rims, 4.10 rebuilt platinum tranny, poly bushes, and RSR 28mm front and 25.4mm adjustable sways!

1984 GTV-6 - 80K miles
Grant is offline  
post #22 of 99 (permalink) Old 02-19-2012, 04:00 PM Thread Starter
enablieri
Platinum Subscriber
 
aikendrum105's Avatar
 
Join Date: May 2006
Location: Melbourne, AU
Posts: 562
Send a message via Skype™ to aikendrum105
Ok - my brain is full.

Richard, reading through, (a few times ) There's a couple of basic points I wanted to make sure I had right. (if you'll indulge me)

* VVT Used for performance (with a cam design to suit) - you time your intake cam such that when retarded the cam is at the optimum position to maximise torque in the idle -> ~3500 rpm mark. ( ~3500 being the area where the engines innate efficiency starts to kick in) Then you actuate the VVT to advance the cam - increasing overlap to place the cam at a better position to maximise power in the ~3500 -> redline range. Your ignition advance curve needs to be setup to match this cut-in point - retarding if you have that mapping ability, or restricting max advance / retarding the dizzy overall at the expense of off idle performance. You may not be too concerned with idle stability / light throttle load economy / emissions etc for your application here

* VVT Used for emissions - you design your intake cam a little differently, and time it such that when retarded, the cam is in the best position for low engine emissions (and possibly better economy) under light load conditions, like idle, light throttle, cruising and decelerating (engine braking). In this position the cam is useless for making any real power / torque - so you need to monitor engine load through a variety of artifice to actuate that VVT at the slightest provocation to get that intake cam back in it's overlapped position for torque and power. You only get two VVT positions (on this engine), you've used one for that light load emission area, so the actuated 'performance' position means your cam profile has to cover the off idle -> redline torque / power in one timed position relative to the exhaust cam (rather than having a position for lower rpm torque, and a position for higher rpm power)

Your ignition advance probably needs standard or a little more advance at idle / light load - with a good reduction / retard whenever the VVT actuates to prevent pre-ignition - which is excacerbated by the fact that the VVT is kicking in a much lower revs under load in this setup.


How does that sound ?

And if that's the case (and I have to ask this) - is there any option with the standard TS intake cam to time it further advanced at the inactive VVT position (at the expense of emissions / idle quality) to give more overlap when the VVT actuates (with more torque / power) Or is further than 6 degrees with that profile counter-productive and likely to bend things ?



Appreciate the help.

Cheers,

Scott Murray
'04 156 JTS Sportwagon -- brilliant car for the daily, kids taxi and parts hauling

in officina -
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

'66 Giulia Super 105.28.720988 -- TwinSpark+MS3+ITB+COP
'65 Giulia Sprint GT 105.04.753710

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


che figata -

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
aikendrum105 is offline  
post #23 of 99 (permalink) Old 02-19-2012, 04:23 PM
Richard Jemison
Platinum Subscriber
 
Alfar7's Avatar
 
Join Date: Apr 2005
Location: Pensacola, Fl. U.S.A.
Posts: 5,777
Beating a dead horse.

Here`s some simple statements for you guys that can`t seem to get a grip on the system

First, I could care not less about emissions. Period

Two, You do not need to adjust ignition timing relative to advance or retard of the V V T. The engine should be at max advance by 3500 RPM.

Third. Cams lobe design determines where lobe position should be at Idle/unadvanced V V T, as when it is advanced, you still have to have piston to valve clearance. My customers get full set up information.

Enough...

Richard Jemison
RJR Racing

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

"When you are dead you don`t know it.
Only those around you are distressed.
Same with stupid"
Alfar7 is offline  
post #24 of 99 (permalink) Old 02-19-2012, 04:57 PM Thread Starter
enablieri
Platinum Subscriber
 
aikendrum105's Avatar
 
Join Date: May 2006
Location: Melbourne, AU
Posts: 562
Send a message via Skype™ to aikendrum105
I think I just got helped to death

Appreciate your thoughts though, I did ask for them

Cheers,

Scott Murray
'04 156 JTS Sportwagon -- brilliant car for the daily, kids taxi and parts hauling

in officina -
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

'66 Giulia Super 105.28.720988 -- TwinSpark+MS3+ITB+COP
'65 Giulia Sprint GT 105.04.753710

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


che figata -

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
aikendrum105 is offline  
post #25 of 99 (permalink) Old 02-20-2012, 04:15 PM
Registered User
 
Join Date: Mar 2005
Location: Milpitas CA
Posts: 2,984
hehe RJ might not care about emissions but I would also point out that many times a good performing engine may also have good emissions. bad emissions many times are due to bad tune and bad tune is bad performance.
When this falls apart is when we do tricks to fix something we do not or cannot control.
one good example is det at WOT if we did not get any det we would run a perfect mix with the best timing. but in realty we have problems at WOT and we get det.
the head shape is not the best, so what can we do (a hack) we retard the timing some.
hack #2 wast gas run pig rich and use the wasted gas as a charge cooler.
now that is not good emissions but that is the easy hack to help the det problem.
but if we could keep the timing opium and keep the mix right we would make even more power and have good emissions if it was not for that pesky det problem.

1987 black Milano Verde, 1987 (made in 1986)blue $200 gold with ABS and LSD
1972 White spider 2000 Veloce
slyalfa is offline  
post #26 of 99 (permalink) Old 02-21-2012, 06:54 AM
Registered User
 
Join Date: Feb 2010
Posts: 52
VVT control in much more responsive when it is TPSvsRPM based. I tried MAPvsRPM and did not like it. I have to admit I did not try to operate VVt only based in TPS. Maybe I should...
But anyway, if you want accurate VE maps and fast responsive engine due to VVT I don't see any other solution except table switching based on TPS.
Car manufacturers always implement many maps in their ECU's, I guess that it the only way to control accurately an engine under all running parameters.
madk4speed is offline  
post #27 of 99 (permalink) Old 02-21-2012, 01:27 PM
Registered User
 
Grant's Avatar
 
Join Date: May 2004
Location: San Jose, California
Posts: 3,771
Send a message via AIM to Grant
Richard,

If you want to help, please be professional. No one is asking you to log onto your computer and post on the internet. I'm here to try and help others as they have helped me in the years prior as I learned more and more about these cars we love.

That being said, toyota's VVT on the 4ag is 30 crank degrees of movement. That is probably why I have to retard the cam at high RPM.

Second, for the intake cam: if the intake cam advances, the intake valve opens earlier and closes earlier too. If it closed later....the duration would have to be changed, which is impossible with out a second lobe of course (vtec). So no, I don't agree with what you are saying unless we are having some kind of terminology conflict.

1987 Milano Platinum - check for many new items. [B][COLOR="Red"]
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
[/COLOR][/B]

1989 Verde - Harsh shocks and SS rears, 27mm torsion bars, stainless lines, pads, 16X7.5 rims, 4.10 rebuilt platinum tranny, poly bushes, and RSR 28mm front and 25.4mm adjustable sways!

1984 GTV-6 - 80K miles
Grant is offline  
post #28 of 99 (permalink) Old 02-22-2012, 03:16 AM Thread Starter
enablieri
Platinum Subscriber
 
aikendrum105's Avatar
 
Join Date: May 2006
Location: Melbourne, AU
Posts: 562
Send a message via Skype™ to aikendrum105
On the motronic thread - Festy has just posted a handy diagram of the Motronics Spark advance at WOT - showing the hefty retard when the VVT kicks in. here

Quote:
Originally Posted by festy View Post
3 WOT advance curves for what I think is the 3 fuel octane settings.
The numbers look low, but keep in mind that VVT is activated when the WOT table comes into play.
There's a 10 degree reduction in advance just when VVT is enabled, and the extra 5 odd degrees advance at 5000 rpm lines up with VVT being deactivated at that point too.


(And also that max advance is reached in the 3000 rpm area, just as Richard said.)

Interesting that with the VVT active the max advance seems to be only about 16-17 degrees, (compared to a standard nord dizzy which is more in the 28 or higher area) and appears to drop off again from 3200-4000, before it spikes back up to give the extra advance when the motronic cuts the VVT out at 5000. More emissions trickery probably.

Anyway - a good place to start with the curve on the MS. (at least the initial VVT retard amount - perhaps not the dropoff at the top )

Cheers,

Cheers,

Scott Murray
'04 156 JTS Sportwagon -- brilliant car for the daily, kids taxi and parts hauling

in officina -
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

'66 Giulia Super 105.28.720988 -- TwinSpark+MS3+ITB+COP
'65 Giulia Sprint GT 105.04.753710

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


che figata -

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
aikendrum105 is offline  
post #29 of 99 (permalink) Old 02-22-2012, 03:43 AM Thread Starter
enablieri
Platinum Subscriber
 
aikendrum105's Avatar
 
Join Date: May 2006
Location: Melbourne, AU
Posts: 562
Send a message via Skype™ to aikendrum105
I ordered the MS2 kits months ago, and finally got around to soldering them up.

I bought the kits through DIYTune.com - it's worth subscribing to their newsletter - they had a 10% off promotion which prompted me to get stuck in and order all the goodies I'd been eyeing off.

The kits are -very- well labelled - you can see the little zip-lok bags everything comes in - the assembly instructions on the web are super-clear, but muddy a little once you start to apply customisations for your application. In my case the SAW wave output my EDIS ignition modules require need a small modification.

I also bought the Stimulator board (the smaller board with all the trimpots / jumpers) - This 'pretends' to be an operating engine - allowing you to change temps / throttle loads / sensor input etc on the bench and verify the MS operates correctly. Also very handy for testing for glitches in maps etc that can be hard to pickup when running in the car. They do pop up assembled on Ebay now and again quite cheap as you normally only use it when first constructing the MS. But I find them gold for diagnosing issues after you've been running the car for a year or two and all construction / operation info has well and truly fallen out of your head (at least that's what I found on my GTV6)

As they say on the MS forums - the Stim kit is good soldering practice too if you're new to it, or a little rusty. Start there

As has been mentioned - it's not going to be as reliable perhaps as an OEM grade system, unless you take a lot of care with assembly, the quality of your solder joints, the bends you use on resistors / transistors etc to reduce fatigue, and using using things like non-conductive hot-melt to secure components from vibration. Helps of course to mount the thing inside the car in a nice cosy location away from the weather and such.

Because I'm not using any of the old Motronic relays etc, I also bought the MS relay / breakout board - tidies that side of it right up into a nice compact unit. Particularly as the car is a '66 and only had one relay (horn) to begin with.

The GTV6 had all that available already, so the MS was more fun to adapt to a stock L-Jetronic loom, and was hot-swappable with the original Ljet box with only a few quick changes in the engine bay (AFM, MAP line etc)
Attached Images
  

Scott Murray
'04 156 JTS Sportwagon -- brilliant car for the daily, kids taxi and parts hauling

in officina -
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

'66 Giulia Super 105.28.720988 -- TwinSpark+MS3+ITB+COP
'65 Giulia Sprint GT 105.04.753710

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


che figata -

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
aikendrum105 is offline  
post #30 of 99 (permalink) Old 02-22-2012, 02:29 PM
Registered User
 
Grant's Avatar
 
Join Date: May 2004
Location: San Jose, California
Posts: 3,771
Send a message via AIM to Grant
My guess is that is way too little advance. I brought up the point in that thread a while back.

At 3000 rpm with VVT on, and 11:1 compression pistons on 91 pump gas, I'm using 25 degrees of timing.... with VVT off i'm using 32 degrees at high load and 3000 rpm. I haven't tuned a TS but I bet that timing is like 10 degrees to conservative across the whole board. Which is huge.

1987 Milano Platinum - check for many new items. [B][COLOR="Red"]
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
[/COLOR][/B]

1989 Verde - Harsh shocks and SS rears, 27mm torsion bars, stainless lines, pads, 16X7.5 rims, 4.10 rebuilt platinum tranny, poly bushes, and RSR 28mm front and 25.4mm adjustable sways!

1984 GTV-6 - 80K miles
Grant is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Alfa Romeo Bulletin Board & Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome