Well i'm just entertaining some fantasies here maybe but is it possible. I Know where there is a 4.2l fsi (engine only) from an rs4 for sale and i was wondering if it is possible to drop it into a B5 s4. Would i need to find everything for the engine like tranny ECU etc?

 

Just buy a b6 +

It's not worth the time, effort, money, or thought.

Sorry, but that's the truth.

 

Well i thought as much. Could you humour me though and outline what i'd need in terms of parts i'm just interested to know. Think about it as a kind of sleeper car project.

PS no need to be sorry. Only reason i even had the thought was because i saw an engine for sale for a decent price with only 10k on it.

 

Anythings possible, but logistically a k04 turbo kit would be a much better choice. You would CERTAINLY need the ECU and wiring harness at least. Even IF it is possible to keep the existing drivetrain there would be alot of custom work. If you have to ask its out of your ability. IMO forget the idea and buy a k04 kit if you wanna go fast. Hate to sound like a buzzkill but its not gonna "drop in" you might be able to force it in with tens of thousands of dollars, a shop, and lots of experience. Sorry if its not the answer you wanted.... reds right on.

 

yea, the 4.2 is a great motor, but nothing competes with turbos. I am pretty sure the transmission from the rs4 wont even fit under the B5. the B5 is too small i would guess. probably not possible without making your own chassis and bodywork and just using a b5 shell. but then again, thats not a B5 anymore...

 

Oh there are no answers i'm looking for only knowledgable opinions. i was just hoping they had same mounting and compatable gearbox. Wishful thinking i know but i couldn't find it myself and figured you guys would know straight off. I know you can tell i'm a total newb here but i'm just looking for a information in order to learn so i can form a project that isn't a complete waste. I have access to a machine shop and am educated in engineering so i'm not completely ignorant and realise the time and effort needed for these kinds of things.

I don't know why but just buying something straight doesn't do it for me. I'm a tinkerer i can't help it and i need something to focus on.

Anyway. If you don't mind i'd like to throw something by you guys feel free to kick the crap out of it i won't take it personally. Firstly i need to explain my logic i'm actually irish and living in ireland and i don't know what your tax and insurance is like in the US but here in ireland it ****** expensive. Any car above 3litre costs 1566euro to tax and generally these engines will cost at least that to insure. So at todays exchange rate thats around 4000 dollars a year before you even turn her over. I'd like powerful car but i cant justify the expense. S4 i can do but wouldn't it be great to save myself a few k a year by maybe spending some time and money now and save in the long run(maybe!).
So the logic bit now, well classic cars cost exactly 44Euro to tax no matter what engine and insurance is in the low hundreds depending on what you value the car at but here's the fun bit we only judge a classics age by the chassis no. no matter whats attached to it it will remain a classic legally. So you see where i'm going? I'd like to combine modern reliability and effiency and power with old school looks to make a powerful sporty car that doesn't cost me nearly as much to keep (ignoring normal running costs). I propose to take the inards of a reasonably modern Audi awd v8 and put it into a 30 year old car. What you think eh. I've got ears and years fire away.

 

It pains me to think of what happened to the RS4 that that engine came from.

As far as cramming the 4.2 into the B5 -- I don't even know if it would fit under the hood without some major mods to the chassis. I don't know if you've ever worked under the hood of a B5, but there is basically no room to work. IMO, cramming a 4.2 into a B5 is unrealistic.

Have you considered looking for a B6 with a seized engine or something like that?

 

You'd have to modify the entire engine bay, realistically you will throw out everything the B5 had and need everything the rs4 had under the hood. Radiators, piping, washer fluid reservoir, EVERYTHING. Not worth the price and labor, buy a B6 or an RS4 otherwise forget about it...