rick4.2L

What differentiates the different audi 4.2L engines? 2000 - 2004 A6 4.2L=300 Horespower
2004-2006 S4 4.2L=340 horsepower
2005 A6 4.2=335 horsepower? Why not 340?

I guess I just don't understand why the 2005 A6 4.2 only has 335HP vs 340HP and what differentiates all of these engines? Different bore? higher compression? different heads? intake??? I have a 2003 A6 4.2, are there any engine mods I can do to increase HP besides a chip? Thanks Rick

Kimchee

i believe the extra power came from a different intake manifold, tuning and free exhaust flow... similar differences between the S6 V8 (340hp) and the A6 4.2 V8.

You're pretty much limited to the hp increases in the 4.2 as there isn't much support for it. You can squeeze an extra 20 hp from a chip and an exhaust, just don't expect miracles.

I guess it's time to upgrade to the RS6.. twin turbos baby!!

baskinblack4.2L

From what I have seen the difference is spread threw 3 things

1 cams
2 rev limmit/ tuning
3 intake

all the motors you mentioned have the same comp ratio, bore and heads

BrianG

For now, the biggest performance upgrades for the 4.2L are exhaust and engine chips. I have a SuperSprint exhaust that is good for about 10hp and Milltek 4.2L downpipes that you can get from Stratmosphere. I haven't installed them yet, but I was told to expect 30hp for the downpipes. I think that is a bit optimistic, so I'm hoping for a total of 30hp from the SS exhaust and Milltek downpipes. You can also get an engine chip from a couple companies GIAC, APR, Powerchips, etc. The chips are good for about 15hp, I would guess.... So, with all this, you are looking at maybe 40-45hp gain.

If that's not enough, PES is working on a 4.2L supercharger for the A6/S6/S8 that is due to hit the market this summer.

Stay tuned.

ESN

And, for '07, the 4.2 will be direct injection FSI @ 350 hp.

4ringdriver

even APR is touting nice gains on their own site.

http://goapr.com/Audi/products/ecu_upgrade_a627t.html<ul><li><a href="https://forums.audiworld.com/allroad/msgs/110780.phtml">click allorad</a></li></ul>

Limey Dude

Iv'e been wondering why the A6 4.2 has 300BHP compared to the S6 4.2 of 340Bhp. I started to look through ETKA to establish the differences in these 2 engines but haven't finished. I can confirm that the part numbers for CAMS are indeed the same and that the profiles and durations of the cams are the same.
This leads me to believe that the main differences are:
1.) Inlet manifold, (looks the same but notice the S6 only has one inlet vaccumn diaphram on the front of the block, compared with the A6 4.2 which has 2. The S6 may be similiar to the A8's 4.2 in which the 2nd diaphram is on the back of the block closest to the bulkhead (firewall))
2.) Engine mapping, I figure this is different as the S6 has slightly poorer fuel consumption -2mpg approx. Also the redline for the S6 is set a little higher than the A6 4.2
3.) I also understand that the exhaust manifolds and exhaust systems are tuned and allow more HP than the A6 4.2 system.

I will confirm more by reviewing the various computer tools I have for these cars.

You may be interested in other cars that use Audi power plants?

1.) The Spyker C8 has a N/A Audi 4.2 V8, that produces 400BHP, why can't we have that sort of power?? Obviously they worked hard on the cams, inlet, outlet and ECU's to get this performance.
2.) The Spyker C8 spyder T has a tuned version of the RS6 4.2 and produces 525Bhp.
Link here &gt;&gt; http://en.wikipedia.org/wiki/Spyker_C8

3.)The Gumpert Apollo has a tuned version of the RS6 4.2 and produces 650Bhp / 627 lb-ft @ 4500 rpm. She can do 0-60Mph in 3secs.
Link here &gt;&gt; http://en.wikipedia.org/wiki/Gumpert_Apollo

Kimchee

4.2 in the A6/S6

Kimchee

heavily to 300... so it's just bringing back the 340~350 that's lurking beneath.

Although, I'm still calling Bull****.

GTA_Driver

With the compression ratio of 11.0:1, I wouldn't be running a supercharger with more than 4-5 lbs of boost for any sort of long term reliability (we're talking more than 3 months).

5 lbs usually increases power output by about 30-40%.