Heads from 2.8l natural aspirated on RS4?

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gregsback

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	Heads from 2.8l natural aspirated on RS4? « on: December 28, 2012, 08:16:45 AM »

Hi,
I would like to know if anyboby has experience with 2.8l natural espirated cylinder heads on a RS4 (2.7BT)?
many thanks in advance
Greg


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prj

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	Re: Heads from 2.8l natural aspirated on RS4? « Reply #1 on: December 28, 2012, 08:23:44 AM »

Quote from: gregsback on December 28, 2012, 08:16:45 AM

Hi,
I would like to know if anyboby has experience with 2.8l natural espirated cylinder heads on a RS4 (2.7BT)?
many thanks in advance
Greg

You can change the cams, but I would not change the heads.
The 2.8L is a big port head on the intake and on the exhaust.
The S4 2.7TT head is a small port head on intake and exhaust.
The RS4 2.7TT head is a big port head on the intake, but small port on the exhaust.

The smaller ports on the exhaust prevent the exhaust gases from expanding too soon and better maintain their exhaust velocity.
This helps to increase spoolup.

So the question is about your application... how much power you are aiming for.
The intake port shape on the RS4 head is also different, and specially angled injectors are used in the intake manifold.


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gregsback

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	Re: Heads from 2.8l natural aspirated on RS4? « Reply #2 on: March 31, 2013, 12:51:01 PM »

Hi prj,
I am struggling with a vehicle where the heads are changed. This Car has a Problem with too High exhaust gas temperatures. Even with series Production calibration. The temperature increases at n>4500rpm higher than 945deg. Then t3 limiter Becomes active. To make the Story short: all sensors and all actuators of this Engine are already changed. If you Want to decrease the T3 you have to go to very early timing (20deg earlier !!!). This is Not a prefered Way for me to go. Therefore i Would like to understand what is happening in this engine. My thinking was, that due to the missing thumble of the head, the combustion moves significant towards Outlet valve opens. This would explain a high temperature. But i do Not have an idea of the amount of combustion elongation due to missing thumble. And i heard voices saying that a change to N/A heads is never a problem. But to be honest i have doubts about that. But i have no experience regarding the change to these cylinder heads.... Does anybody have experience?
Many thanks in advance
Greg


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ddillenger

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	Re: Heads from 2.8l natural aspirated on RS4? « Reply #3 on: March 31, 2013, 01:29:16 PM »

Is your cam timing correct? Are you using naturally aspirated cams?


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gregsback

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	Re: Heads from 2.8l natural aspirated on RS4? « Reply #4 on: March 31, 2013, 11:07:35 PM »

Yes, the Cam Timing is correct and double checked 4 times now. The Inlet Cam is natural aspirated, the exhaust is rs4. All valves (in and Out) are from rs4.
Therefore i slightly disagree regarding the valve diameters.


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666s4

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	Re: Heads from 2.8l natural aspirated on RS4? « Reply #5 on: March 31, 2013, 11:38:28 PM »

I have used 2.8 heads with NA intake and S4 exhaust cams. That's a good mod on an 2.7 engine.


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gregsback

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	Re: Heads from 2.8l natural aspirated on RS4? « Reply #6 on: April 01, 2013, 12:06:22 AM »

Could it be that the Cam actuators do not work properly? How can i Check this in a relieable Way? Dies anybody habe experience with the Cam actuators?
Many thanks in advance


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ddillenger

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	Re: Heads from 2.8l natural aspirated on RS4? « Reply #7 on: April 01, 2013, 12:16:43 AM »

Quote from: 666s4 on March 31, 2013, 11:38:28 PM

I have used 2.8 heads with NA intake and S4 exhaust cams. That's a good mod on an 2.7 engine.

No, it's not. It's a bad idea all around on a k04 car.


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gregsback

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	Re: Heads from 2.8l natural aspirated on RS4? « Reply #8 on: April 01, 2013, 12:48:52 AM »

Performance wise it might not be the best choice i think. But i am more focusing in the Existing Problem with too high T3 with series Production calibration....


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s5fourdoor

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	Re: Heads from 2.8l natural aspirated on RS4? « Reply #9 on: April 01, 2013, 11:03:12 AM »

Can somebody that knows this give a real answer: At what HP or TQ level do the big ports actually matter? Are we talking like greater than 5000 RPM with 25 psi or greater?
My 2.7t holds 21 psi to redline and supposedly this won't add any tangible hp.


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666s4

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	Re: Heads from 2.8l natural aspirated on RS4? « Reply #10 on: April 03, 2013, 12:55:48 AM »

Quote from: ddillenger on April 01, 2013, 12:16:43 AM

No, it's not. It's a bad idea all around on a k04 car.

Ddellanger i might not know about tuning the ECU, but when it comes to hardware I know my ABC's About 20 years long. I am not doubting you but I have done and been around a lot of builds. Having big ports 99.99999% are neutral (meaning don't lose power) If not making at least a little more power.
Big cams might hurt (meaning duration not lift) overlapping can be the issue.
Big ports with NA 2.8 intake cams do make power Wink


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666s4

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	Re: Heads from 2.8l natural aspirated on RS4? « Reply #11 on: April 03, 2013, 01:18:13 AM »

Quote from: nehalem on April 01, 2013, 11:03:12 AM

You will make some hp at high rpm and very high boost over 30psi. At 21psi just run 2.7 heads with rs4 or 2.8NA intake cams.


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prj

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	Re: Heads from 2.8l natural aspirated on RS4? « Reply #12 on: April 03, 2013, 04:15:58 AM »

Quote from: 666s4 on April 03, 2013, 01:18:13 AM

You will make some hp at high rpm and very high boost over 30psi. At 21psi just run 2.7 heads with rs4 or 2.8NA intake cams.

RS4 cams = 2.4NA


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666s4

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	Re: Heads from 2.8l natural aspirated on RS4? « Reply #13 on: April 03, 2013, 08:37:59 AM »

Quote from: prj on April 03, 2013, 04:15:58 AM

RS4 cams = 2.4NA

thats what I said. But some people don't know that. They refer to them as RS4 cams.


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prj

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	Re: Heads from 2.8l natural aspirated on RS4? « Reply #14 on: April 03, 2013, 08:46:56 AM »

Quote from: 666s4 on April 03, 2013, 08:37:59 AM

thats what I said. But some people don't know that. They refer to them as RS4 cams.

You never did, I just clarified.


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