UrS4boy

"I would like to point out some aspects about 3B/ABY/AAN vs. ADU vs. 7A cams:

Analizing data I have there are some in my opinion interesting things to consider when choosing among different cam's options:

3B/ABY/AAN:

TIMING:
Intake opens 3° after TDC, exhaust opens 42° before BDC

DURATION:
Intake 202°; Exhaust 213°; no overlap -> intake opens 12° after exhaust closes;

ADU:

TIMING:
Intake opens 13° after TDC, exhaust opens 24° before BDC

DURATION:
Intake 202°; Exhaust 205°; no overlap -> intake opens 12° after exhaust closes;

7A:

TIMING:
Intake opens 7° before TDC, exhaust opens 42° before BDC

DURATION:
Intake 224°; Exhaust 213°; no overlap -> intake opens 3° after exhaust closes;

ADU exhaust on 3B/ABY/AAN:

TIMING:
Intake opens 3° after TDC, exhaust opens 24° before BDC

DURATION:
Intake 202°; Exhaust 205°; no overlap -> intake opens 2° after exhaust closes;

7A exhaust on 3B/ABY/AAN:

TIMING:
Intake opens 3° after TDC, exhaust opens 42° before BDC

DURATION:
Intake 202°; Exhaust 213°; no overlap -> intake opens 12° after exhaust closes;


This means that:

1) as a matter of "TIMING" RS2 cams are designed to give best flowing efficiencyes at lower rpm compared to 3B/ABY/AAN. High rpm efficiency is however ensured by a higher exhaust lift of 9.5mm instead of 8.6mm (and by the higher flow and boost rate of the RS2 turbocharger). I belive RS2 cam settings where designed to have best compromise between low rpm and hig rpm performances.

2) using a 7A exhaust cam with a 3B/ABY/AAN intake cam, timing will be the same but you'll have 10.5mm lift instead of 8.6mm which is a sensible difference in final EFFECTIVE FLOW which will more likely be usefull in the higher rpm. Since timing is not changed there are no changes in efficiency rpm ranges.
Compared to the ADU cam you'll have more high rpm efficiency but will have less low rpm torque."

In answer to a question about the 7A exhaust cam vs the RS2, Marco responded:

"...I mean that on the "real stuff" things might be slightly different, so experiences might give better infos.
What I can say is that, "reading" the timing, duration and lift, RS2 exhaust cam has slightly more "retarded" timing and less "duration" (therefore theoretically being better setted to lower rpm) compared to the 3B/ABY/AAN exhaust cam, but having sensibly higher lift that will increase effective average opening area thus increasing flow expecially on higher rpms.

So it seems to me a very well engeneered "compromise" design.

If you just look at top hp and/or track use of the car, the 7A exhaust cam will for sure give higher outputs but will also stress a little more the valvetrain (higher lift).

About using only the RS2 exhaust cam and keeping the 3B/ABY/AAn intake cam, it seems to me (always "reading" from a teorethical poin of wiew) the intake timing will be slightly advanced (10°, thus giving some better flow on higher rpm), while having same duration and (I suppose) lift. This "hybrid" solution will make intake open closer to the exhaust closing (10°) but still not overlapping, so should be fine.

What I cannot "read" anywhere, is that the two cams (intake and exhaust, I mean) could be designed to perfectly work together so that the even apparently small differences between ADU and 3B/ABY/AAN intake cams could suggest to use both the RS2 cams (but I recognize the real difference is made by the exhaust one)."<ul><li><a href="http://www.s2forum.com/forum/showthread.php?t=1477&amp;page=2">Reference link to the S2 forum for the non-believing</a></li></ul>

J.Alves

Hy.
I have S6 AAN and i'm trying to change to RS2 specs, i've changed everything less the intake camshaft that still is from the AAN since in the ETKA show that is the same for both engines and now the engine don't run properly.
Is realy the intake camshaft the same or do i have ajust it by
retarding the 10 degree's diference that is shown on the RS2 timing specs?

UrS4boy

The two intake cams are the same. Most people who go "RS2" do NOT change the AAN exhaust cam. Some go to the 7A exhaust cam. If you used the AAN cam position sprocket wheel, with the RS2 exhaust cam, you don't have to worry about the 10 degree issue (assuming that you lined the two cams up properly as per AAN requirements).

J.Alves

I have install both cams like if was AAN standard engine but it dosen't run properly so i measure the timing and the intake cam was opening 3 degrre's ATDC and i retarded to 13 degree's ATDC like RS2 standard and it runs fine.
My doubt is: if the cam is the same why can't the engine run properly being the cams installed like it says on workshop manual?

UrS4boy

Which camshaft sprocket did you use? The AAN or the RS2 sprocket?

J.Alves

By camshaft sprocket you mean were the camshaft is powered by the
chain?
If is that what you mean the exhaust camshaft and sprocket is from a ADU engine and the intake camshaft and sprocket is froam a AAN engine.

UrS4boy

...powered by the cam belt, as shown here (with the silver cam sensor shutter behind the sprocket)(Note: The red arrow are pointing to the G40 cam position sensor):



Here is what the stock cam timing should look like at TDC No.1:



On the other side, it should look like this on an AAN:

J.Alves

I've change the AAN cam sprocket,water pump, timing belt, turbo, injectors, pressure regulator, MAF, ECU, exhaust mainfold, wastgate and exhaust cam to RS2.

The problem is when i install the cams like this:



the engine fails when i touch the throttle and then i retarded the intake camshaft like this:

The red point is the original mark is now and it runs good, why can't run fine with the two marks aligned if the intake cam is the same for the AAN and ADU engine?

UrS4boy

I *think* the problem is you should have used the AAN cam sprocket with the AAN cam position sensor shutter wheel, not the RS2 cam sprocket and shutter wheel. The AAN ECU is expecting the cam position sensor reading 10 deg differently than the RS2 ECU would. I would change the cam sprocket back to the AAN and re-align the cams as per AAN requirements.

J.Alves

The ECU is original from an RS2, the only thing that is from the AAN is the intake camshaft.