Putting 7A cams in a different way.

[lynx]

Hi guys,

I have one question.
First, I hope I will make myself enough clear, for understanding. Because this kinds of terms in english is a bit hard for me (to translate estonian to english).

Anyway, I getting a pair of 7A cams for my engine (3b, adu em, k26/t04e) and I' m a little bit of confused how to install them. I have read may threads about 7A cams, and suggested here is to use only 7A exhaust cam, not the inlet (loosing a torque and not any different in power).
However, here in Estonia some of guys have some of ideas, and I' m asking what You thinking of it.

Ok, taking exhaust cam and putting it one tooth later. And now comes the hard part, how I transale the word they are using. Anyway, they are thining this. Hall (senser??)will go 13,8* later. And result is: -28 +180 +19 =227
There are some terms, that I could not transale in english at the moment, but I' ll hope You will understand.

Anyway, let' s take the intake cam.
They suggest to remove "gearwheel" form it (cam) and put it back in backwards. So, this will make cam 10* earlyer.
And one of the nuber they are sayng, but I can' t translate:
- +42° (52-10=42)

and

- -2° (8-10=-2)

And finnaly putting the hall senser.
Then turning the cam pulley one tooth back (approx. 14* hall senser) and then again putting hall senser back in normal place.

They are all-so telling that this will make much more torque till 5500rpm and hp.

Now I'm asking from You. What do You think about this? Or is there better way to putting 7A cams in 3B engine?

with best regards,

[|Maku|]

What my brother tried to say about 7 cams is that local guys in Estonia have tested this kind of conf:
Outlet cam 1 teeth later (cam gear);
Inlet cam 1 teeth later (this time cam sprocket teeth), remove sprocket and put it backwards, which makes cam 10 degrees earlier.
Specs of this conf would be:
Outlet 28° vUT 17° vOT = 225;
Inlet 2° nOT 42° nUT = 224;
Overlap 19°.
Of course hall sensor must be in the right place. A few local guys have said that it does not matter how you put hall sensor, but i must say that is does matter. I have tested it myself..
One more thing, those numbers may not be 100% accurate!
http://www.friikartul.ee/maku/nukkade_tabel/ (one useful link i have made).

[lynx]

hmm, I like to install cam(s) this weekend, maybe even today, but I have that question.

What do You think this other installing method?
I don' t want to make several tests, to know what is best. I'm going to change cam(s) only one time, but question is, how.

Could You guys suggest something?

P.S> I' d tried to search placing 7A cams but I could find anything.
But if I go for only ex. cam, is it straight swap with original? No any changes (like earlyer tooth etc?)

with best regards,

[newsh]

My understanding is:

a) If you use only the exhaust cam its a straight swap.

b) Valve overlap on a turbo engine is not a good idea. Does that link say that the RS2 cams have overlap though??

[|Maku|]

My understanding is:

a) If you use only the exhaust cam its a straight swap.

b) Valve overlap on a turbo engine is not a good idea.

Would you be so kind and explain why overlap isnt so good idea on a turbo engine? Lets take RS2 cams for example, there is quite big overlap and if i remember correctly then catcams sport cams have quite big overlap.

[newsh]

Would you be so kind and explain why overlap isnt so good idea on a turbo engine? Lets take RS2 cams for example, there is quite big overlap and if i remember correctly then catcams sport cams have quite big overlap.

Well, because the turbo will be pumping a large amount of fuel and air into the exhaust during the overlap, but I'm not an expert, just recalling what I've read here in the past..

I am surprised that the chart you posted shows that the RS2 cams are overlapping.

I'm interested though as I'm getting a pair of 7A cams myself and if there's a way to use the inlet cam and get good torque then I'd like to try it, otherwise I will use only the exhaust cam.

[|Maku|]

I am surprised that the chart you posted shows that the RS2 cams are overlapping.

Jep, so it is.

Right now im useing cams with specs like this:
Inlet 240, 11 degrees before
Outlet 225, 4 degrees before
Overlap 7 degrees.
And i must say that it isnt a very good combo, because engine starts "running" at 4000 rpm (i use rs2 turbo too). Tomorrow Im going to try another combo (inlet 240 25degrees before, outlet 225 10 degrees after, overlap 35 degrees), I will let you know how it worked if you are interested.

But about 7a cams. Have anyone tested both of them with different combos?

[newsh]

(snip)
I will let you know how it worked if you are interested.


But about 7a cams. Have anyone tested both of them with different combos?

Please do.

I think pisobiker may have done some research into this.

[lynx]

anyway, with friend we did to that "scary" test. We changed cams like I wrote top of the topic, and guess what . . . I think 2.3NA going even better, that my s2 does at the moment.

The car just not going anywhere . . . till 5000rpm there nothing that I could proud of it, and after that . . . hmm, I guess 2.3NA even going better.

Anyway, morning we will change cams again, but I think this time original 3B intake and 7A ex. just swap.

thanks anyway

[repo]

If You still want to play, I have some of those in stock:

http://promo.pp.fi/temp/camgear1.JPG

100 eur / piece. incl 22% vat. + freight.

[lynx]

If You still want to play, I have some of those in stock:

http://promo.pp.fi/temp/camgear1.JPG

100 eur / piece. incl 22% vat. + freight.

At the moment I don' t want to play anymore.

But I have some serious problem. Just changed cams, just intake (original). Both cam now like they should be. Mark at the cam pulley and flywheel is like they should be. Also we tested many different way to put hal(l) senser.

The car just can' t do nothing more that 0.5-0,6 bar overboost (before it did ca. 1,7). It' s just kind of boost problem, not related to the rpm, because car choke after 0,5-0,6bar overboost seriously, and there no any point to push it after that.

I think if I put original ex. cam back, the problem still there . . . but I have question, what may cause that?

I just want to drive normal with my car, but at the moment even overtake at the road is dangerous.

with best regards,

[lynx]

problem resolved one way . . . I mean, problem have founded.

There was a "little" boost leak.
The leak was at hose witch comes from intercooler, near engine. Hole was that big, that I could put 2 fingers there.

First thing at the monring I will replace that hose with something stronger.

[|Maku|]

I tried "inlet 240 25degrees before, outlet 225 10 degrees after, overlap 35 degrees" combination and its not very good combination. Max turbo power was at 4500rpm and it was quite uncomfortable to ride.

Right now Im using 7A cams and Im planning to get adjustable sprockets.