7A Exhaust Cam

[Audi_CQ]

Let me put it in another way.Since it all boils down to what you want from the car to perform:

If you had a turbo that spools after 3800-4000rpm would you go for ADU cams or 7A cams ?

7A's if your goal is ~500. Use adjustable chain sprockets and advance the ex ~5degrees. Adjusting both cams 5 degrees will give a bit more low down power, as inlet closes is the most important figure for low down power. If using a small hotside with a lot of backpressure it's best to only advance the exhaust as the increased overlap would kill the advantage of the early closing inlet valve.

[A80Avant]

if i had to buy something else to use with the 7A exhaust cam,then i would go for the aby sprocket then to have same results as using an aby inlet and 7A exhaust.
As my car is fully ADU in all cyl.head parts,the other solution would be to get an adjustable cam gear and use something i could tune in on a remap session.On the other hand,i dont feel very secure with the idea of having bolts on the sprocket cause god knows what will happen if one gets loose...

So for me the main question is : Since im not getting anything out of the engine below 3500rpm anyway, will there be any better results if i chance to 7A cams (both) so i can still have about the same lag AND get better top end results? OR will this setup screw everything around?

IM talking about this with a larger turbo,and the 3071R is a larger turbo than stock,but not that large.Since the bigger you go,the more lag you have,then what is the point in keeping cams that can give you good results from 3000rpm if your turbo is still sleeping at those revs anyway?

[Jamo]

The thing is the RS2 never came out in america so how many RS2 cams has Javad seen on a dyno?

Really think your not going to get the answers here, it's going to be what works best for you on the car.

If I run another dyno day be interesting to try and quantify some results on some members cars.

I just can't wait to the see the results of using the NM inlet and exhaust cams

[A80Avant]

i may have to be a guinea pig then.
unless i get a straight answer from MRC or something....or an answer at all for that matter.

[Jamo]

I reckon you may be able to measure the difference without a remap and gtech.

[A80Avant]

well obvious difference would be best if i had a remap after the change.safe side of not going lean as well.

[Jamo]

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.


Marco

Damn good post

[Bram]

Aaaaaa, there is the data from Pisobiker. I have been looking for that for a long time!
So advancing the 7A cam by 5 degrees would only solve earlier spool-up and not low-end torque?

[BedaS2]

ABY,AAN,ADU have same intake cam...

[Jamo]

ABY,AAN,ADU have same intake cam...

We know, if you read the post it says timing.

The ADU has different timing due to the Cam wheel trigger being in a different position.

[BedaS2]

You know ideal timing for turbomotor ?

[Jamo]

There's a thread about with timing plots, ABY cam with RS2 cam wheel I believe was one of the best results or 7A cams

It's a recent thread

[BedaS2]

Sorry about my English ,is no good :-(

[BedaS2]

I have 7A cams...

[BedaS2]

GT35R ,7A cams ,wosner piston,h rods,11.4s /209km/h drag with bad clutch :-)