Toolmaster

Anyone happen to have an either "stock" or even a modified ignition advance table as it relates to either boost and/or RPM?

I'm in the process of thinking of upgrading my car to an aftermarket ignition/fuel system and want to see what the stock chips (or even what other people are running on modified systems).

Thanks in advance! If you'd like, email me at jayc@rennlist.com.

Jay
86 951
Toolmaster

Russ Murphy

Jay,
You know, the stock map would be really useful/interesting. Rage2 posted his map for his initial/stock injector setup here. <a href="http://www.virgeweb.com/rage2/944t/2002-02rage_sdsmap.xls" target="_blank">SDS Map</a>

Toolmaster

Russ -

Thanks for the info! It's helpful, but it'd be more helpful to know the boost curve there too. That gives me a single line on my chart (albiet an aftermarket line) which is certainly more info than I had this AM.

Thanks !
Jay

Russ Murphy

Jay,
The columns that are labeled FUEL MAN PRES and
IGNITION RET MAN are the boost values in psi (the positive numbers up high) and the partial vacumn values in inches of mercury (the negitive numbers down low). Sorry, but I'm not sure if that's what you meant by "boost curve".

Toolmaster

Russ -

Right - I'm with ya. But what this table doesn't show is rpm/advance/boost.

For example, at 4000 rpm, I could have just shifted and have lesser boost than when I got to 4000 rpm in a higher gear.

What I'm looking for is a table that has rpm on the x axis and boost on the y access, with the advance degrees as the cells in the table.

Kinda like:

Boost Pressure in PSI

0 val val val val val
1 val val val val val....
2
3
4
5
6
7
8
9
10
etc

RPM 0 100 200 300 400 500 600 700 800 900 etc...

With Rage's table, I can fill in a line of this table, as I know the advance for a specific rpm and boost value - but as I can be at many different boost levels for each rpm, which would change the advance, I'm hoping to get the actual table.

Thanks!

jay

rage2

You have a map of every rpm vs boost from my table. Say you are at 5000rpm, 12psi boost. You would take the 5000rpm value (36) then add the retard value at 12psi (10@11.8psi) and you have the setting there.

Chris White

Can I jump in with a question? How did you establish the advance curve for your SDS set up? I have seen some other curves for highly modified 951s that get over 42 degrees of advance (not at high boost of course).
Thanks
Chris

Toolmaster

Rage -

AH! The missing link.

So I could then use your table if I were to rename the columns as such...

Ignition RPM is RPM
Val next to it is the initial advance

Ignition retard MAN is boost pressure
Val is the value to add/subtract at that boost pressure

Right?

If that's true- then I owe you big time! Thanks!

jay
(Ps - what hp did this map give you?)

Toolmaster

Rage -

So if I understand our chart correctly,

2000 rpm I have a base of 26 degrees. At 10psi boost I add 10 to get a grand total of 36 degrees advance for that situation.

One more question though...

the Man pressure - is that positive pressure or absolute pressure? Like is 10 psi really 24.7 psi, or 10 psi.

Thanks a bunch man!

Jay

rage2

You subtract the retard value, so you would have 16 in your example. And the boost values are in PSI, so 10 is 10PSI.

My timing values were from the factory Porsche workshop manuals. It'll be tweaked to be a bit more agressive when the weather gets better.

Russ Murphy

Rage,
I've got two questions. 1. Were the IGNITION RET MAN values gleaned from Porsche and were they modified to account for the low octane gas availible in Calgary? 2. Why are the RPM FUEL values significantly greater than estimated value from SDS's cylinder displacement/injector size table?
Thanks man.
Russ

rage2

1. Crappy gas

2. Old injectors? The car was running pretty lean when we used SDS's values calculations. Remember, it's just a baseline, I've changed injectors and refined my map a lot more since the one I posted =).

Russ Murphy

Hey Jay,
what aftermarket ignition/fuel system are you getting?

Toolmaster

Russ -

Well, I'm sorta in the process of deciding just that. I figure if I'm able to find the right dealer/reseller (wink wink) then I'll make the decision then.

Part of my goal for this thread is hopefully to meet up with the right person to work with. Any aftermarket system that we purchase needs a good support base. For example, I'd rather go to a Porsche guy/gal for tuning than the maker of the unit if at all possible.

Thanks!

Jay
86 951 (We can rebuild her. Make her stronger, faster, better....)