This is just for the Guru's here....okay since I have my motor street ported I wanna get the most power I can out of it, ie advancing the timing....Now My question is using the stock CAS how can I adjust timing at 6000 rpms? or how does advancing the timing at idle change timing at 6000 rpms under boost? what does the ecu do to the timing at WOT? I assume it is pressure sensitive?

 

What EFI system ya running, mate? If it's stock, you can't do any real specific load (i.e. this particular RPM at this particular vacuum/boost) tuning at all -- All you can really do is adjust the CAS as a baseline.

If you've got an aftermarket EFI, I can help you out with where you'd wanna run both leading and trail-split.

B

 

I'm running the stock ECU with my piggy back SAFC fuel controller....I kinda figured that but how does baseline adjustment of the CAS effect high rpms and boost situations?

 

It'll affect them either beneficially (to a point) or detrimentally (by having the CAS too far advanced at base). Honestly, I wouldn't mess with it just yet. Wait 'til you can fine-tune individual load points with an aftermarket EFI system.

B

 

after market efi meaning entire ECU?

 

Yep -- Replacing the entire ECU. Sorry, I'm using to talking a certain way and sometimes forget that I need to adjust my terminology to fit.

B

 

well I'm going to try and trick the ecu and see what it does to the timine, hook up an air compressor and pressure regulator to the MAP sensor and watch the timing at the same time and see what happens...though I don't know if it would be the same under load.....

 

If your using a MAP sensor then I take it you have an aftermarket ECU?

 

No I mean the pressure sensor same thing....

 

You can advance your timing up to 18 degrees leading and 15 trailing. Then you can open the top of the cas and time each rotor trailing separate.

Half way between the marks is about 20 degrees advanced, so a little less for leading.

This will still be safe, when the ECU advances the timing normally, under boost or load..

With the timing advanced you will need to lower your boost or run high grade gas to prevent any predet., as safety.

 

ecu advances timing under load and boost? I thought it was retarded under boost....

how do you advance the timing separte from the Leading and Trailing? don't they advance with each other?

 

inside the top of the cas is where you time separate. No the timing is advanced while giving it gas

 

I am not a fuel injection guy but I was allways told that you are supposed to retard the timing so in times of high boost you have enough room for the timing to advance and catch up to the large amounts of air and fuel. My car is carbed so it is most likely different. When I retared the timing I noticed a big difference though. The engine lopes at idle and sounds tough and with my msd I have all the spark I need at 20+ lbs of boost.

 

thats what I thought NeilTII....but I guess my Turbochargers book by Hugh MacInnes is right..

 

I think you guys are slightly confused.
Stock leading timing at idle is 5* ATDC.

So, even if you are running X amount of timing BTDC under boost, your timing is still advanced somewhat.

Just as an example, I run 35* BTDC under cruise loads and 12* BTDC under full load (WOT at 14psi).

So even though, my timing is retarded under boost, its still advanced compared to the stock timing...

Anyways, I'm pretty sure the stock ECU works in the same manner...

 

Yeah, I agree. It advances when you hit the gas, but the boost sensor retards it when you are under boost. (But its still advanced, just not as much.)

 

okay the question still stands what how does the timing underload and boost change if you change the timing at idle?.....

 

According to BDC: around 27*BTDC at 0 boost and about 20* BTDC at 7psi boost.

So if you advance the timing by 5*, eg from 5* ATDC to 0 BTDC, then it would go up to 32* at 0 boost and 25* at 7 psi, etc etc

 

well the cas tells the ecu where -5 is, and form that the ecu runs on its timing maps. if you advance the timing, the ecu doesnt know that and it the timing will be advanced everywhere the same amount. or to put it another way the ecu has the timing curve in it, and you cant change the shape of the curve, only the height, without a standalone, or a dizzy

mike

 

Damn this **** is confusing the hell outa me, eVilRotor do you mean advancing idle by 5* to get 0* BTDC?

does this also advance the vaccum advance? So its basically impossible to advance the timing as radically as you did with the stock setup?

....so basically the timing curve will stay the same but it will be lifted up the number of degrees you advance it at idle?

okay now for the next question...if I were to run a 1st gen distributor / CAS would that solve the problem of not being able to change the stock timing curve?

 

I think so. It will just follow its curve, but with the 'new' advance that you dial in with the CAS...

 

You really should not be messing with the base timing on the CAS.&nbsp If you have no idea on what total timing is safe and what advancing (or retarding) timing does to an engine, you're asking for trouble.

As a side note, an A'PEXi Super IT-C can handle advancing the timing at 6kRPM only...


-Ted

 

I do know what the effects are (better gas milage, more power all around) and it seems that some people who just posted are telling me good Timing setup for a TII, I'm not saying I'm gonna go out an crank my CAS up to 10* advanced on the baseline... whats and A'PEXi Super IT-C

also will I still gain power from my street port if my timing is still stock?

 

http://www.belperformance.com.au/apexi/html/itc.html

Yes, you'd still gain power from street port even with stock timing.


-Ted

 

but I could adjust the timing if i installed the 1st gen distributer right?