7A Exhaust Cam

[Jamo]

The RS2 cam is better than the 7A exhaust in an RS2, no loss of torque with the RS2 cam low down.

The 7A cams is an upgrade over stock S2 cam exhaust cam, I can't think of a reason to fit it to an RS2 as there's no gains to be had in reality.

If your running a Garrett turbo I'd do the reverse and look for an ABY / AAN exhaust cam as the Garretts seem to perform better on the stock cams according to european tuners.

[audiman]

If your running a Garrett turbo I'd do the reverse and look for an ABY / AAN exhaust cam as the Garretts seem to perform better on the stock cams according to european tuners.

Depends if you have a girl sized Garrett I had a man sized one that did nothing until 4k!

[Jamo]

Depends if you have a girl sized Garrett I had a man sized one that did nothing until 4k!

Now now you'll give us Garrett envy

[Bram]

Well, I have laying around both intake and exhaust cams from my ABY, from a ADU and a 7A engine. So actually I can do whatever I want
I also have a Dahlback cam pulley that could advance the timing if needed with a 7A exhaust cam.

However I am still not sure what is the best solution for my GT3071R 0.63

Currently I have both ADU cams installed and my tuner mapped the ECU on it. The car pulls very strong over a large RPM range (see attachment), but I read several times the combination of ABY inlet and 7A outlet (5 degrees advanced) would give me approx. the same low-end torque and add extra HP top-end compared to using both ABY cams after a remap.

Is this assumption still valid?

[Bram]

If your running a Garrett turbo I'd do the reverse and look for an ABY / AAN exhaust cam as the Garretts seem to perform better on the stock cams according to european tuners.

Can you explain this maybe? I do not see why the standard ABY cams would be better in combination with a Garret????

[Rusty]

A turbo car is a little more complicated than a NA car for cams as there is the back pressure of the turbine to consider. The free flowing turbine in a Garrett might not produce enough back pressure to prevent low-end blow by with cams that overlap. As the stock cams don't have any overlap this might explain why they work better over the whole rev range. Companies like catcams use much shorter duration exhaust cams than inlet.I will be trying the 7A inlet cam with stock ABY exhaust and pulley and see what happens... the thinking being that the exhaust cam is fine for bigger power than my little k24 so it's not really worth uprating it. I might be horribly wrong, I might get it right, have to wait and see... NA theory indicates that it should be better but I'll lose low end torque a little.

[Jamo]

Can you explain this maybe? I do not see why the standard ABY cams would be better in combination with a Garret????

Different turbos have different flow characteristics just because one cam works well with one turbo doesn't mean it will work with another it's a dark art so to speak.

Most success with the garret turbos has come from using both 7a inlet and exhaust or both standard AAN / ABY

The standard ones work well due to no overlap and the fact the garretts produce very little boost below their threshold.

I wouldn't follow the crowd with the 7A cam as the RS2 exhaust cam is a better choice as an upgrade IMO and if you have stock AAN / ABY cams I wouldn't upgrade.

The 7A cam to be used as an alternative due to the prohibitive price of the RS2 cam on the forum.

Of course this is all IMO and as you have the cams mix and match to see which one is better although I think you'd need remapping to get benefits out of them.

[s2bug]

ok, here's a first shot:

the turbo is basically made of 2 parts: cold and hot side, the cold side inlet is called the inducer (I guess because that's where the air gets induced) and the hot side outlet (the one that goes into the downpipe) is called the exducer.

The KKK turbos are separated into several families: K24, 26, 27, 28, 29 and there's also hybrids.

The #s refer to the hot side's scroll volume in cubic centimeters, thus a K26#6 hot side supposedly has a scroll volume of 6cc's.




The stock S2 turbo is a KKK24, it's exact denomination is K24-7000 because the cold side's ID is 2470. It has a K24 #6 hot side with an exducer bore of 48mm
The RS2 turbo is called K24-7200, and, although called K24 is a full K26 turbo, it has a larger shaft than a K24, the hot side is a "special" K26#6 (it is special because it is the only hot side that KKK has ever made especially for the 20v turbo 2.2 liter engine. The bearing housing (center part) is a K26 part number (ID= 2672) and so is the cold side. The exducer bore on the K24-7200 turbo is 54mm.



IMO and if it were only for me, the RS2 is your best bet! the cold side can go as high as 370 safe and reliable HP (possibly a bit more though) and as much as 650-700Nm of torque (see SteveH's stock rods, 600 is safer and 700 seems to be the absolute limit for the stock rods) if everything else is done accordingly (exhaust cam, IC, injectors, rod bearings, head gasket and last but not least ECU remapping)

the RS2 turbo gives full boost at around 2800 RPM in the 2 higher gears when accelerating WOT from 2000 RPM or so, and this is due to its hot side mainly.

If it were for me, and this will be the turbo on my next car, it will have the RS2 hot side, RS2/K26 bearing housing and a K27/29 cold side, this way about 400 HP will be available at the top of the rev range, but most important, low end torque will be there as early as 3500-3700 RPM.


HTH,

Mihnea

Hi Minhea

Looking at a similar upgrade but bucks dependant concidering the GT3071 :O) as opposed to the RS2 on 034


For a neglible difference the GT seems stonking! not beeing totally turbo tech I pass the question to you.

Which and why would be best?
Many thanks

J

[Rocco]

the 3b cams are worse than the ABY-AAN cams'?? they are an upgrade cams for the 3b???

aniway i have the 7A cams in my home ready for mount it. looking for RS2 tuned specs around 350-400hp wich maybe are the best combo??


wich for inlet??? 3b,aby,aan,rs2,7a.....

and for exhaust ? 3b,aby,aan,rs2,7a...??



.-------
Tomas

[Jamo]

3B cam is different not in timing but because it has the dizzy drive on the end of the inlet.

3b \ aby \ aan are all the same timing to my knowledge.

[GazzaG60]

ive put a 7a ex cam in mine after then rebuild. not run it yet but will report.

cams are a funny game as stated before. from what i managed to learn whilst planning a solid lifter 16vt was that for high end with a big turbo for high power a set of good NA cams can be set to perform.

many big power guys run NA cams and tune the overlap to around 10-12 deg.

i was gonna run a set of schrick solid lifer cams around the 280-300 deg mark in the corrado, solid lifter to rev 8500. top end power would be great and the lack of low end help keeping traction. vehicle characteristics are important too. lots of lift on those cams too. about 12.5mm.

may get myself a set of adjustable cam gears and mess with the overlap and see what i can do.

[Jamo]

Gazzag60 there is a great thread on motorgeek where Javad has the adjustable cam chain gears I cna't find it however.

[GazzaG60]

cheers ill have a look.

my info cam from a friend in the states who's a 16V GURU so same rules apply.

he made 517whp on standard timed cams on a 16v so it must work.

this is almost free horsepower so well worth a look.

[A80Avant]

so what you are saying is that the ADU exhaust cams combination is better than the 7A exhaust cam + ADU inlet cam? on a garrett setup?

Has anyone tried this setup before?IS it better to fit both 7A cams?or will the lag is going to get even more?

[A80Avant]

appearently i read in a german forum that Peter from PKmotorsport that his view is that matching the 7A cam with an ADU inlet it wont give anything obvious because of the overlap.Dope!!!! so me getting the 7A cams was useless??? Will it be any better if both of them are used??