7A Exhaust Cam

[S2central.net]

IIUC - it is the 7A inlet cam which changes the engine characteristic a little in that the engine doesn't generate as much torque in the low-mid range with the 7A IN cam - compared to stock 3B, ABY, AAN.

In saying all of this, I am due for a new timing belt and some new top side gaskets anytime soon - for a little extra effort I guess I could drop in my 7A EX cam to try it out on an otherwise stock engine - with the exception of homefried ECU of course.

Paul

[Jamo]

According to Mihnea Paul in previous posts, the 7A exhaust losses some low end torque but that it can be mapped back in.

Also running a 7A exhaust will lean out the AFR at high revs if not mapped for it.

The 7A inlet changes the car a hell of a lot less torquey and moves boost higher up the rpm.

Mihnea corrected me on this when I thought it wasn't different and having a car with a 7A inlet I agree.

I made this thread a sticky about a month ago with Doug's RR plots

http://www.s2forum.com/forum/showthread.php?t=10461

[S2central.net]

Good man - I like some evidence - especially on something like this where I haven't tried anything for myself. I'll go have a look at that sticky thread.

[Rusty]

...300 HP is more or less a dream on a K24...

[Bram]

What would be the real effect on changing the ADU exhaust cam for a 7A? Will the torque spool up later? Or will it remain about the same when properly mapped and give higer output power higer in the revvs?

[Rocco]

and bosting at 1,7bar??? haha sure the turbo its in it work limit

one thing,somedays i,ve tryed with the stock k2470 bosting at 1,9-2.0 bar

[Rusty]

Nope, standard homefries boost

[newsh]

How long would it take me to swap cams over? I fancy doing a back to back comparo with the 7A and Stock exhaust cam, I've had the 7A one in for a year or so now and it would be nice to try the stocker again, I'm missing some low down grunt. Do I need a tool to lock the cam wheel, can't remember

I guess its just, line all the marks up, whip the camwheel off keeping tension on the belt, swap cams and bolt it all down again? Looks like I'll have t take a fair bit of piping off though..

[Bram]

According to Mihnea Paul in previous posts, the 7A exhaust losses some low end torque but that it can be mapped back in.

Also running a 7A exhaust will lean out the AFR at high revs if not mapped for it.

The 7A inlet changes the car a hell of a lot less torquey and moves boost higher up the rpm.

Mihnea corrected me on this when I thought it wasn't different and having a car with a 7A inlet I agree.

I made this thread a sticky about a month ago with Doug's RR plots

http://www.s2forum.com/forum/showthread.php?t=10461

Jamo, so what you are saying is that when I drop in a 7A exhaust cam in my ABY I can add a cam pulley from Dahlback, PKM or Cat Cams, after the fitting I have to put the cam timing 5 degrees advanced, and finally have my tuner adjust the ECU software? So what I expect to get is about the same low-end torque as with my ADU cams and have higher output power mid- and top end?

[Bram]

Bump

[Rusty]

By advancing the cam you're reducing the power gains and reducing the low end losses also, it won't be quite like the ADU but it should be better than just fitting the 7A on stock pulleys. That said I bet they're a pain to setup properly and you'll need to have a play to get things right. Search for "cam duration" and go back 3-4 years for some useful threads with durations, lift etc. for the OEM cams.

I had forgotten that the ADU exhaust cam is low duration but that the 7A and 3B/ABY/AAN are all the same duration as the 7A but with less lift. The ADU also has a cam pulley that retards the cams 10degrees for improved top end power. All makes things a little confusing doesn't it!

[Rusty]

Like this one linky although it's also on the first few pages of this thread

[audiman]

Or, just fit the exhaust cam keep stock pulley and forget it. The loss of torque will be so small you will hardly notice it.

for every time you move the timing on the cam pulley, you will need a remap to gain from it. Fit it with stock pulley and remap and forget.

Just my 2 pence worth. Im sure i can proved wrong, but for the tiny loss in torque and the gain in top end power (where a small turbo'd S2 will benefit), i think i am right.

[A80Avant]

so basically with the 7A exhaust cam and the ADU inlet cam,you loose a bit of a torgue in the mid range and you gain some hp in the top range?is that it?

just got my 7A cams today and was doing some thoughts...

to me it seems that the car is pulling nicely in the top range,but im aware of them not pulling as hard...Or is that because the ADU exhaust cam gives so much torgue in the middle range that makes this feeling come up?

i did get the 7A cams to use only the exhaust one,with stock pulley.I was thinking that the lag difference is unnoticable(ross didnt have more than me),and the top end power could be definitelly a gain of some 20hp

am i wrong?

[audiman]

The differences are so different depending on the spec of your car. My car ran 2.5 bar peak holding 2.2bar at redline. So the loss of torque was fixed by a bit more boost. and the 7a cam allowed the engine to pull even at 7.4k.

Fit one and find out. Thats the only way of seeing what change it has on your car.