7A cams installation

[Greg_S]

When going for 550 hp, would you then prefer that I put in the both of them? Still cant deside up to go for the RS2 inlet cam, if I put in both 7A will the boost be coming later? or doesnt it affect the spooling of the turbo? Must also be a fair chance on boost a little bit before when the 7A exhaust cam has higher lift and more air will pass. Right now it max boostes at about 4500-4600 rpm.

Really would appreciate more oppinions on installing 1 or both cams?

Thanks again
Thomas

When doug had both 7A cams fitted he lost power, was running approx 450 at the time so put standard inlet cam back in and it improved.

Would be interested to hear how you get on with 7A & RS2 inlet combo. With 7A exhaust added the boost will come in slightly later but you will get more top end power.

[Pembo]

Just had some 7A cams reprofiled by Piper for the rally car. The attached spec sheet says .....
INLET Duration 264 valve lift 10.87mm Open 22 BTDC Close 62 ABDC
EXHAUST Dur 254 V/L 10.17mm Open 57 BBDC Close 17 ATDC

Engine not rebuilt yet so no performance data to share.

[Greg_S]

Just found this which I think marco posted sometime ago with part numbers and details of cams

[S2central.net]

It depends on how high you need to rev the poor thing. At high boost the valves can take a beating and I would suggest these

http://www.034motorsport.com/product_info.php?products_id=397

also titianium retainers

http://www.034motorsport.com/product_info.php?products_id=357

and then uprated valve springs
http://www.034motorsport.com/product...roducts_id=368

Hmmm - exotic stuff. Kinda curious about these valves on two fronts -

1. How they make such a big difference if the diameter is stock. I presume they are 'waisted' a bit more aggressively than factory ?

2. Are the exhaust valves sodium filled as per stock applications ?


Paul

[Corey]

Hmmm - exotic stuff. Kinda curious about these valves on two fronts -

Are you on about me being exotic?

1. How they make such a big difference if the diameter is stock. I presume they are 'waisted' a bit more aggressively than factory ?

Yup they are cut back for increased flow and would get even better results if matched to a properly ported and flowed head

2. Are the exhaust valves sodium filled as per stock applications ?

No the exhaust valves are made from solid Iconnel and the inlets are stainless steel. They will out live the stock ones in high boost applications, this does away with the fear of the sodium filled stock valves burning out.

[AnLe]

Answer me this, why there are even available performance cams if they only reduce power? Why don't people drive with totally round cams if that is the best way?

7a versus 3b/aby/aan are so marginally different that normal engine tuner that has not got audiglasses over his eyes will lauhg at these 212 degree cams what most people in audi scene consider hardcore upgrade. If one engine produses less horsepower then all engines will? How much was backpressure with std cams and how much more there were with the 7a's? There could even be situation where bibber turbo wouldhave given better torg at low rews becouse the engine was sufficating to the small turbine housing. (don't know that setup so this was just an speculation)

[Jamo]

Answer me this, why there are even available performance cams if they only reduce power? Why don't people drive with totally round cams if that is the best way?

7a versus 3b/aby/aan are so marginally different that normal engine tuner that has not got audiglasses over his eyes will lauhg at these 212 degree cams what most people in audi scene consider hardcore upgrade. If one engine produses less horsepower then all engines will? How much was backpressure with std cams and how much more there were with the 7a's? There could even be situation where bibber turbo wouldhave given better torg at low rews becouse the engine was sufficating to the small turbine housing. (don't know that setup so this was just an speculation)

You forget one factorm the 7A cams were designed for NA cars not a turbo car.

The 7A exhaust cam works well with the S2 due to higher lift and greater exhaust time opening without overlap

The 7a inlet is another matter entirely.

Custom cams are designed to spec based of the original turbo timing

[Jamo]

Are you on about me being exotic?



Yup they are cut back for increased flow and would get even better results if matched to a properly ported and flowed head



No the exhaust valves are made from solid Iconnel and the inlets are stainless steel. They will out live the stock ones in high boost applications, this does away with the fear of the sodium filled stock valves burning out.

They come highly recommended on motorgeek.com and have been on my watch list for a while now after reading about them.

It just depends on how far i want to go on my upcoming project.

[AnLe]

good points, but good na engine is good food for turbo.


But yes, right component is allways the correct way to go, now explain me what differs na and turbo cams? catcams and shircs has aroud 270 degrees and something like 10 or 11 mm of lift, how they are different from na cams? ramp? and lobe? are so different from each other?

ps. I had my 7A cams open 1,4mm intake and 1.0mm exhaust open at tdc.

[Jamo]

good points, but good na engine is good food for turbo.


But yes, right component is allways the correct way to go, now explain me what differs na and turbo cams? catcams and shircs has aroud 270 degrees and something like 10 or 11 mm of lift, how they are different from na cams? ramp? and lobe? are so different from each other?

ps. I had my 7A cams open 1,4mm intake and 1.0mm exhaust open at tdc.

Valve overlap, in the NA engine valve overlap is good, in a turbo it's not good

http://www.mx6.com/forums/archive/index.php/t-134786.html

http://www.sdsefi.com/techmods.htm

[S2avant450]

Thanks a lot for all the information.

But... Still bit confused, most here suggests only installing the inlet cam, so think thats where im heading.

The engine will be ready to install this weekend, so will have to decide soon. Looking forward to get it started up and running.

/Thomas

[AnLe]

well, as that is true, when you have back pressure then overlap will not be good thing, but as I am interested only to go faster, it seems somewhat odd to choose an turbo that makes backpressure.

There is other thing to overlap, to make an fuelmap that is little too rich and too little advance enginebrake situation (taking foot of the gas pedal) overlap gives possibility to feed raw gas in exhaustmanifold keeping gasses hot and wheels spinning and engine cooler.

When changing cams, you should make new fuel&ignition maps, just swap cams will not give true picture, if you are using maf, it fixes fuel issue as good as it can, but if more advance can be given to better breathing engine, you are missing a lot.

[Corey]

They come highly recommended on motorgeek.com and have been on my watch list for a while now after reading about them.

It just depends on how far i want to go on my upcoming project.

If you don't go as far as you want you will not be satisfied because you will always think "what if..."

[S2avant450]

Re hi

Well this weekend my engine will be assembled - Here are the changes:

- New Verdi rods
- New Wiseco piston (81,5 mm)
- cylinder walls being "horned" to 81,5 mm (making with 9/100 in oversize vs. pistons)
- New Sachs Sintermetal sport clutch (old had few marks)
- enlarging my plenum chamber with 5 cm (old version made to much pressure on fifth cylinder)
- Installing Greddy A/F meter
- Getting the injectors tested (dont know english name)
- Installing 7A cam/s, think it will be cam as in only the exhaust cam.
- Run about 1000-1500 km with absolutely no boost, to give the new horned walls in cylinder the best start.
- Remapping of engine at RH Motorsport

Finish, and hopefully happy.

So its not about going all the way, but by current turbo, is maxed out at 530 hp, and after so much money spent, I would off course like to save the last 400 pound on valves, springs etc. But as I allready wrote, if needed, I will buy the valves etc. But in my world, the 7A cams is not even needed to get the 500-550 hp? But as I now have bought em, and heard many really good things about the cams. I surely want em/it in.

The hole list is just to show; off course the car will be remapped after putting the cam/cams in...

Then; thanks again

/Thomas

[S2avant450]

7A cams on Ebay

By the way, just saw these, if anybody here is interested.

http://cgi.ebay.de/Audi-90-Coupe-S2-...QQcmdZViewItem

/Thomas