zebinheimer

ok so ive been thinking about engines that are worked to the bone with pistons, rods, port/polish, etc etc. Now as far as the 4.2 goes (40v, lets use the year 2000 for ex.) What work can be done at what cost to bring it up to say 400hp (sounds fair right?) WITHOUT forced induction. I welcome any and all ideas, as the title states youre schooling me so keep in mind i know a relatively small amount about engine work, just trying to get educated here lol

p.s. cost efficiency is not a priority here as I just want to learn.

thanks

ub2slw

Should I dare make the claim? Okay i will...I'm at or above 400hp in my BHF (05.5 S4 4.2) I over-reved the engine and had to do a rebuild of the top end. I had a smooth port and polish on the exhaust side and a rough port and polish on the intake side (see my profile for pictures) I also added RS6 exhaust valves that are 2g lighter. Intake valves are the same. With the APR software, APR downpipes and a x-pipe my car was dead even with my friend's RS4. Overtaking c5 corvettes on the highway was no problem....

To raise the HP even more I could have had a custom thinner head gasket made to bump the compression ratio up, changed cams (still qestionable in my eyes) added full exhuast and air filter (still no proof of gains over stock airbox)

HOWEVER you can find my previous posts in this area about reducing weight more importanlty rotating mass (clutch, fly wheel, wheels and tires) I sent my fly wheel clutch combo to the 2benetts and at the time there was nothing available to replace the dual mass setup...since then I remember a company now offers a single mass setup (MTM i think) but drivablity would be a concern.

So in all you can spend $3,000 to remove and replace the engine $300 for the P&P, $1,200 for downpipes, $600 for software, $100 for the x-pipe, $1,000 for single mass fly wheel and clutch setup. OR buy a chipped RS6 with an aftermarket suspension since the DRC WILL crap out.

zebinheimer

method behind the madness is this...

I want this vehicle over the 2.7t because of:

1)reliability (SAP, turbos, TBB, boost leaks the whole nine.)
2) For some "insane" reason I just love the 4.2.
reliability, power/liter (as compared to say a 540i, or most other v8's out there.), the sound, etc.
3) finally, widebody ftw.

theres the automatic issue too but that WILL be dealt with, Ive been doing research over the past few months to come up with a parts list and method to a 6 speed swap, I have professional help too so I wouldn't be going completely alone.

Now, lets say I wanted to do the following:

1)rebuild
2)P&P
3)rs6 valves
4)software(if available for the 00')
5)x pipe/dp's
6) merge collector/better flowing headers.

how much would each net me, both in power and cost on average?

Also with the high compression setup via a thinner HG, wouldnt there need to be piston/rod work done as well?

Thanks a lot for your time
p.s. I'm not completely talking out of my *** here with these plans, I believe its better to buy a 10k car and put 10k into it then buy a 20k car. so youre input will be put to good use lol

zebinheimer

Would it be practical as opposed to cams and valves? (given availability ofcourse).

ub2slw

Some work was done to that to really open her up...
Everything is going to work together to make more horsepower...more air in more air out the better the performance. Not one single item will give you a great advantage. The software is needed to advance timing and correct fuel mixture...which means you need better flowing heads to get the air in then better flowing exhaust to get the air out. Tuning is going to be the most critical portion of your setup. Which means to get the ABSOLUTE most out of the car you'll have to have a qualified tuner AND a dyno to dial the car in.

The bottom end is pretty strong, i wouldn't recommend opening the block. The only advantage would be to blance the rods. If you did want to replace them, I'm not aware of any rods and pistons available off-the-shelf, it doesn't mean that they don't exist though.

BTW I completely respect and admire your diligence to work with Natual Aspirtation, but the A6 did come in a S-sline 2.7t with 6peed...if you were dead set on the V8, the RS6's are in the mid-to-high 20's

ub2slw

it is my understanding that the only major difference is the manifold has longer runners on the S8. However I've never seen one and wouldn't know if it DID fit the engine...would you be able to close the hood?

audikillsbmw

034 sells forged H-beam rods for 4.2's.

audikillsbmw

installed an S8 engine with a new exhaust, chip, etc. I'm personally going the supercharger route, because that's a bit easier (in my book.) Good luck though. FWIW, 034 Motorsport also carries titanium valve retainers for 40v V8's. A nice way to reduce valvetrain weight..

audikillsbmw

S8 has a 2-stage manifold, unlike the 3-stg unit in a normal 4.2.)

audikillsbmw

Not bad for $1100. And FYI, VAST offers ported stock exhaust manifolds for our cars, as well as an EFK (which I have.) Probably a lower gain than a set of headers, but those won't be ready for another month or two (courtesy of a fellow V8 owner, S6skier.)