Cams 7A inlet and exhaust RR results

[Jamo]

So the 7A exhaust cam is superior to the RS2 exhaust cam then?And how does the 7A cam compare to the 2 litre 5cyl 20v exhaust cam?

I know Mark H said that the 7A cam was better than the RS2 cam in his car.

[martinjs]

And how does the 7A cam compare to the 2 litre 5cyl 20v exhaust cam?

The NM cam is the same as the 7A i think.

[4WheelDrifter]

Not quite. Less lift & shorter duration.

[caterpillar]

you may try some more cams too like the catcams.....www.catcams.be

[robo]

I just wondered if exhaust cam with 13.5mm lift would be too much????
I got price from catcams for both cams at £ 598+vat

[fivepotnoodle]

Doug,
can you tell me what mods are in your engine in respect of turbo, EM and exhaust system.
Thanks

Must be top secret or he's full of dung

[audiman]

Its no secret, Dougs car has changed massively since this. The best setup that i have tried in my car was 7A exhaust and stock 3b inlet.

7A intake cam reduces torque and creates more lag, with a minimal increase in power. I have tried both 7a and 3b intake cams. I have no dyno figures, but the 3b intake cam was better for everyday driving, and gave 400rpm less lag than 7a

[Jamo]

Must be top secret or he's full of dung

Doug has a MRC600 thread with the details of his engine build.

Strange comment on a 2 1/2 year old thread!

[s20ale]

Obviously doesn't know Doug. !!!

[dainys]

Its no secret, Dougs car has changed massively since this. The best setup that i have tried in my car was 7A exhaust and stock 3b inlet.

7A intake cam reduces torque and creates more lag, with a minimal increase in power. I have tried both 7a and 3b intake cams. I have no dyno figures, but the 3b intake cam was better for everyday driving, and gave 400rpm less lag than 7a

I think with both adjustable 7a cams could have more power, more torque and the same lag

[audiman]

We can all think. Do you have proof that this is possible??

[Rusty]

Just my ramblings:-

Both 7A cams:-

The power loss is could be due to the exhaust cam being too long duration and the charge blowing through the cylinder at lower revs, hence the increase in lag and loss of low end torque. Using the world of normally aspirated engines as a guide a shorter duration exhaust or an exhaust timed to close earlier would allow for better low end performance than with both 7A cams. Top end performance would be reduced. A longer duration inlet is not a bad thing, it just has to be matched to the exhaust. Catcams use this theory in their turbo cams but to get more flow they give much more lift on the exhaust.

3B/ABY inlet + 7A exhaust:-

This prevents a loss of midrange power as the inlet opens later and so there is less blow-by as the overlap is less.

However, there is also the issue of the turbine and EM restricting flow so you can only take the exhaust cam so far before any further increase in duration becomes pointless or even has a negative effect if the exhaust gasses flow back into the cylinder.

[Bram]

posted my question in the other thread

http://www.s2forum.com/forum/showthread.php?p=313223&posted=1#post313223

[fluk3]

is there anyone of you knows if you can drive with std valve springs if you mount a 7A exhaust cam. ?
can the engine still take the 7200 rpm as the original?

[audiman]

its fine, same part numbers in fact. will rev to 7800 without problems