4.2 Single Turbo Build

[rotorhead24]

Hello Everyone,

I have left the played out 2.7 scene and am looking into a v8 s4/s5 in the very near future. This will be my play/race car and will be heavily modified. I plan on a large single turbo putting down atleast 800hp. I am considering picking up a 4.2 block at the time and starting porting/polishing/blueprinting to drop in a chassis later down the road. There is a local listing for an 05 s4 4.2 with low compression for 700$.

Is this a good place to start? I am no too familiar with the 4.2 and its fallacies. Are there years/vin nums to avoid for certain reasons?

Plans for the engine:

Polished crank
Forged rods/pistons
Ported head
Studs
Valve seat job

Thanks for the read. I plan on having a lot of fun with this project...

*****I have wandered outside Audizine to find the best info in a single thread that has resolved nearly all my questions and hopefully others you may have too:

http://www.motorgeek.com/viewtopic.php?f=10&t=37659 ******

[seanj130]

Hello Everyone,

I have left the played out 2.7 scene and am looking into a v8 s4/s5 in the very near future. This will be my play/race car and will be heavily modified. I plan on a large single turbo putting down atleast 800hp. I am considering picking up a 4.2 block at the time and starting porting/polishing/blueprinting to drop in a chassis later down the road. There is a local listing for an 05 s4 4.2 with low compression for 700$.

Is this a good place to start? I am no too familiar with the 4.2 and its fallacies. Are there years/vin nums to avoid for certain reasons?

Plans for the engine:

Polished crank
Forged rods/pistons
Ported head
Studs
Valve seat job

Thanks for the read. I plan on having a lot of fun with this project...

If you plan for 800hp, you are not concerned with any motor problems as you will have to rebuild from ground zero. 700$ sounds like a deal, running or not as you will begin the build.

[LOUDERPLEASE]

"At least 800hp".

Significantly more than 2x the original output.

Where will the intercooler(s) live?

+ you're baulking at $700 something tells me that won't even cover the beer tab.

[Scottydo]

Supercharge it. Finding a single turbo setup for that motor plus a intercooler housing is going to be very difficult.

[FastEddie]

Do it...................only because I want to see something different lol. Good luck though!

[BCsniper]

...sounds like you need to do a bit more research. Where do you plan on getting these forged rods and pistons for the engine? Do you know anyone other than JHM that supplies them? ...didn't think so, now just go ask JHM's how much new forged rods and custom sized pistons will run, then let me know if you still want to do this.

read the first post here from Justin and get a little more background on the BHF 4.2
http://www.audizine.com/forum/showth...and-discussion


You talk about just buying the motor to build, what car is it going to go in? My advice to you, since it seems like it would fit your goals easier, would be to go out and find a timing belt V8 from an A6/8, S6/8, or RS6. The engines are more robust and the cost associated with them should be a bit less.

Or go big ballin and get the motor from an S5 or RS4 since they have forged internals already

[stormscr3]

...Or go big ballin and get the motor from an S5 or RS4 since they have forged internals already

I agree with this ^

[Austonwerner4]

Have you guys seen the 034 STK?

[iHaveBoost?]

^ for the B5 S4...

[B6JoeS4]

Here we go again

[rave]

It's old but I guess I'll say it and get it out of the way....

[mrjasper3mn]

It's old but I guess I'll say it and get it out of the way....

+1

[rotorhead24]

Thanks for the advice already guys, i already have a good idea what im doing with the plumbing outside the engine , right now just trying to avoid a generation of block that would need to have the cyclinders sleeved. good to hear that they did make some 4.2's with forged internals. i am aware of costs involved with builds, as this is not my first rodeo.

I have heard before that the rods are interchangeable from the 2.7 to the 4.2 and maybe even the 1.8? can someone elaborate or confirm this? This is not a budget build so please dont think i will be cutting any corners to save a few bucks. I have learned the good value of doing things right the first time and not letting my toys own my life.

I have considered having JHM build a full long block, but where is the fun in that ?

[rotorhead24]

+1

If you plan for 800hp, you are not concerned with any motor problems as you will have to rebuild from ground zero. 700$ sounds like a deal, running or not as you will begin the build.

...sounds like you need to do a bit more research. Where do you plan on getting these forged rods and pistons for the engine? Do you know anyone other than JHM that supplies them? ...didn't think so, now just go ask JHM's how much new forged rods and custom sized pistons will run, then let me know if you still want to do this.

read the first post here from Justin and get a little more background on the BHF 4.2
http://www.audizine.com/forum/showth...and-discussion


You talk about just buying the motor to build, what car is it going to go in? My advice to you, since it seems like it would fit your goals easier, would be to go out and find a timing belt V8 from an A6/8, S6/8, or RS6. The engines are more robust and the cost associated with them should be a bit less.

Or go big ballin and get the motor from an S5 or RS4 since they have forged internals already

This is the exact response i was looking for. I rember reading years ago that some generation of the 4.2's had cylinder distortion problems the lead to seized pistons on even stock cars....

[EUROSWAGR]

I have considered having JHM build a full long block, but where is the fun in that ?

The R&D is already done, I'm not sure you could even imagine how much they have invested in the program or the lengths they have went to gather information for their development. I would guarantee if you try this on your own with Joe Blows machine shop you'll go through multiple BHFs, which will not be cheap. Even if you do get one to run and throw power at it, I have a feeling it won't be running for long.

It's cool to be different, but really man, this isn't the platform to be different with.

[rave]

What about..... C6 S6 V10 swapped into the S4, then, to further impress......



twin turbo.



big cahones status.

[rotorhead24]

or if i was really into wasting my resources...

why not a 6.0 w12 from the a8 saloon, also shared with the continental tt and the spyker tt??....

becuase im being realistic and not pioneering a new nasa project.

[EUROSWAGR]

What about..... C6 S6 V10 swapped into the S4, then, to further impress......



twin turbo.



big cahones status.

I'm curious if you've ever opened your hood and seen your engine bay?

I mean if you have enough money and don't mind hacking apart a perfectly good car anything could be possible, but the B6/7 S4s and a C6 S6 engine bay are probably no where close to similar. Then you want to slap 2 turbos in there...

I like big dreamers, but builds like that just look cool on paper and rarely ever get completed or become a drivable car without a million issues.

[troyguitar]

The R&D is already done...

It's cool to be different, but really man, this isn't the platform to be different with.

R&D might be underway but from what has been made public it is far from done. I have seen a grand total of zero cars over 450whp or faster than that 11.9x quarter mile so far. Am I missing something?

[aks4avant]

Great idea OP. I've seen a complete 4.2 S4 motor fully built on either MTM website or a suppliers website for about $30,000$.
Not cheap, but sounds more like your gonna get your hands dirty so guess that may not be your option. But maybe they could share some
Good info.

Good luck regardless

[Slow4]

R&D might be underway but from what has been made public it is far from done. I have seen a grand total of zero cars over 450whp or faster than that 11.9x quarter mile so far. Am I missing something?

money.
time.
LEGIT demand.

[rotorhead24]

What I have collected from this awesome thread:

http://www.audizine.com/forum/showth...and-discussion

Gen1 4.2 (c4, b4 and older?): Sleeved
Gen2 4.2 (c5 RS6) : more Aluminum with some special metallic coating engineered and imported from the space station that needs reapplied after boring/honing
Gen3a 4.2 (current s4): even more aluminum content, Thin, weak cylinders, sketchy waters and definite headache and castration in the future
Gen3b 4.2 (b7 rs4): Badass and refined that comes with forged internals

SOOO... I need to either start with a Gen1 or Gen3b rs4 block? All other vesrions seem weak in cylinder thickness and keeping the head seated. Cost between those seems it would be night and day. If other are charging 30k for a built longblock, i would say there is some room for savings lol.

I have not ruled out going thru JHM for the build but I guess that is the main purpose of this thread. Since this will be my hobby car, I would like to say I did all or most of the assembly.

[EUROSWAGR]

R&D might be underway but from what has been made public it is far from done. I have seen a grand total of zero cars over 450whp or faster than that 11.9x quarter mile so far. Am I missing something?

I'm pretty sure they are close to releasing some good stuff, but they have been developing their program for maybe 2 years now or more. So that should that say, either 1. it isn't easy like so many 4.2 guys with dreams fail to realize or 2. JHM is making sure that these motors will hold power and last. JHM is known for testing on their vehicles and a very small group so that they can be completely sure their products not only perform, but will be reliable. They aren't in the business of blowing shit up..lol unless it's them trying to blow their own shit up for testing purposes.

No tuning company besides JHM has put any type of R&D into this platform, if it wasn't for them most people would struggle to run high 12s low 13s. Yes I understand these aren't drag cars, but that is a pretty universally accepted test for a cars acceleration performance and reflects the actual power a car is making. Since they came into the game, B6/7 S4s have went from NA pigs with no hope (laughingstock of the B5 S4 world), to cars that can be decently quick. Since their nitrous kit and supercharger kit development, we now have the chance to run 11s...that is pretty respectable and impressive for a 4 door luxury sedan that is AWD and weighs 4,000lbs. Shit if you go to a track and watch domestics, most of them struggle to run 12s let alone 11s, even with 450whp.

I know your kind of new to the platform, but with only one company that really cares... our platforms progress isn't as fast as most of us would like. The community also isn't very big so developing parts isn't going to make them incredibly rich. It also sucks that the cars are dropping in value and becoming more affordable for younger guys with less money to play with. People complain about the price of products all the time and compare them to mustangs and shit. JHM has the market cornered, that's the truth, but their prices are fair considering the quality and performance. The BHF isn't a slap together type of motor, but everything else about our cars is pretty solid so with a built motor option we should start to see some impressive things.

[EUROSWAGR]

Great idea OP. I've seen a complete 4.2 S4 motor fully built on either MTM website or a suppliers website for about $30,000$.
Not cheap, but sounds more like your gonna get your hands dirty so guess that may not be your option. But maybe they could share some
Good info.

Good luck regardless

Most of us have seen that, but who has ever seen a built BHF from MTM? what kind of power did they make? O wait...no one has ever seen or heard of one running... have they?

[0000 V8]

This thread sounds awfully similar to a thread I saw a while ago about a guy who stated all his PLANS and everything he was GOING to do with a turbo setup. There are just too many threads out there like this that get started and die because people dont research before they make big announcements. I cant even FIND that guys dumb thread, thats how insignificant these posts are.

Id love to see all of these plans come together, but I dont recommend stating you are going to do it, without first at least getting started and proving you have the guts and the cash to do it.

Talk is cheap.

At least you drive an allroad

[rotorhead24]

at first first I was looking for some good input once i saw 0000 V8 had posted. but never mind.

of coarse talk is cheap, this forum is free to all isnt it? how about we keep this thread focused on the structural integrity of the different 4.2 block and not other people's failed attempts at building a motor that has been around for about 20 years.

[Perry Bullard]

This thread will eventually die out too.
0000 V8 is right though. Too many people have started up a thread and just never started the build.
So I guess what most of us are saying is we won't believe it til we see it.

[EUROSWAGR]

at first first I was looking for some good input once i saw 0000 V8 had posted. but never mind.

of coarse talk is cheap, this forum is free to all isnt it? how about we keep this thread focused on the structural integrity of the different 4.2 block and not other people's failed attempts at building a motor that has been around for about 20 years.

Comparing all 4.2l V8 blocks is your first mistake. People have built the older generation 4.2l timing belt motors so there is something else you've learned today. I think what 0000 V8 is really trying to say is that you should really just be researching and planning rather than starting a thread about your "plans" to build a motor with a single turbo setup.

Like I usually ask, what is the point of a single turbo setup when there is a centrifugal supercharger setup with all the work already done that is more than capable of pushing more power than most people will ever need?

You throw out 800hp "at least" like it's so easy to achieve numbers like that. The APB 2.7t have been around for 13 years and haven't touched that type of power reliably. I mean come on dude, it's impressive to make power like that on bigger displacement domestic motors that are a dime a dozen and ever machine shop in the world knows how to build so what makes you think that it's not going to be a long road of trial, error, failure and plenty of $$$.

These comments are where most logical members in this forum start to say "BS" and think that a person is kind of a joke and basically talking just to hear themselves talk.

[0000 V8]

So I guess what most of us are saying is we won't believe it til we see it.

Exactly. Its not that we dont want to believe you. I for one would love to see something other than JHM parts just for the sake of having them. Im not personally attacking you OP, hell, Id come help anyone on AZ with a build if they needed it.

I think the intercooler mounting issue could be overcame, but not with out trimming the inside of your bumper a bit. Theoretically, anything is possible, you just need the cash and guts, as I stated earlier.

When you say this will be your "play/race car" what type of racing are you referring to?

[0000 V8]

The reason I asked that question above is this. If you want to do a build as drastic as mine, its ok to go crazy with some things. The options for your build open up when you arent constricting yourself to keeping the car intact as a daily driver, or mostly together. There is a reason I dropped 600 lbs off the weight of my car, even with the cage installed. I literally removed most of the extra weight I didnt need. The car is also not technically street legal. I didnt need it to be.

The other point is this. If you want to make this a race car, you must first decide if you want big power OR big handling. You will likely not achieve both. That being said, if this will be a road course/track vehicle, dont waste your time with the motor yet. If you want something that will go fast in a straight line, then this is more practical of a route, however, MOST practical would be to buy an american muscle car, since they are only good for straight lines and are much cheaper to build.

[rotorhead24]

By play/race car i mean a car that could have indefinite down time to ensure the best build possible. Purely intended for entertainment, going fast and robbing passengers of the ability in inhale air or circulate blood to their extremities while putting my foot into it. I will likely be running a stand alone & digital dash, but I would neever do a ls1 swap to get the results that I want. Ill leave that to the teenagers playing with themselves in the Formula D kiddy club. I know this will be a challenge, which makes it fun for me.

I know about the threads other people start. Ive been around the car world and forums a while, I did a swap in a 87 944 when I was 14.... Maybe I mis-titled this thread. Should have been '4.2 versions - The Good and the Bad'. When I do start this build I will definitely start a detailed thread then.

I will most likely pick up an older 4.2 but Im still having trouble distinguishing which is sleeved and what is not.

I am just trying to start with the best version of the block before I look like the other people that find out later that their cylinder have cracked, or heads lifted, and have woken from their wet dreams to a lady grenade that has left a stinky sweaty outline on their sheets. So that is where I am different from other wannabe posters. Doing research and collecting the advice of others BEFORE ANY INITIAL PURCHASE, Is the the proper way to start ANY project IMHO.

If the 4.2 was such a lost cause, I doubt JHM would have put all they have into R&D. There is a good 15yr gap between the 2.7 and when the new 4.0t starts getting tuned on, which is why I personally feel its time to see what we can to with the 4.2. Audi is in my blood but so is boost. I want to keep it that way.

[beemercer]

I have heard before that the rods are interchangeable from the 2.7 to the 4.2 and maybe even the 1.8? can someone elaborate or confirm this? This is not a budget build so please dont think i will be cutting any corners to save a few bucks. I have learned the good value of doing things right the first time and not letting my toys own my life.

I have considered having JHM build a full long block, but where is the fun in that ?

the timing belt 40v 4.2 had similar rods as the 2.7t, the bhf has a much different rod

the fun would be making the power, let someone else deal with all the bullshit around building the motor

This is the exact response i was looking for. I rember reading years ago that some generation of the 4.2's had cylinder distortion problems the lead to seized pistons on even stock cars....

that'd be the bhf primarily

What about..... C6 S6 V10 swapped into the S4, then, to further impress......



twin turbo.



big cahones status.

LOL

What I have collected from this awesome thread:

http://www.audizine.com/forum/showth...and-discussion

Gen1 4.2 (c4, b4 and older?): Sleeved
Gen2 4.2 (c5 RS6) : more Aluminum with some special metallic coating engineered and imported from the space station that needs reapplied after boring/honing
Gen3a 4.2 (current s4): even more aluminum content, Thin, weak cylinders, sketchy waters and definite headache and castration in the future
Gen3b 4.2 (b7 rs4): Badass and refined that comes with forged internals

SOOO... I need to either start with a Gen1 or Gen3b rs4 block? All other vesrions seem weak in cylinder thickness and keeping the head seated. Cost between those seems it would be night and day. If other are charging 30k for a built longblock, i would say there is some room for savings lol.

I have not ruled out going thru JHM for the build but I guess that is the main purpose of this thread. Since this will be my hobby car, I would like to say I did all or most of the assembly.

I'd say you have the following for v8s

-32v motors, 3.6, 3.7 & 4.2... head is similar to an old VW 1.8
-early 40v motors, dbc
-later 4.2 40v dbw motors, C5 motors, fairly strong and less failure prone
-bhf, 40v mpi timing chain motor... smaller stroke, switched from chemical stripped (no coatings, that nikasil not alusil like audi uses) bores to mechincally stripped bores, higher silicon content, probably the weakest option to use
-32v 4.2 fsi timing chain motors, S5/Q7, forged internals, less issues with timing system/cylinder wall scoring, may be a good option for making power on stock internals
-32v 4.2 fsi t/c high rev, rs4/r8, similar to above but stronger to deal with the rpms, probably the best option

each block is different, same bore and bore spacing and similar materials but some are radically different.

if I were in your shoes I'd do a stock RS4 or RS6 motor, or a built bhf from JHM. There should be an RS6 motor for sale in the classifieds (AudiA4_20T), you'll need to work out the flywheel on either an rs4 or rs6 since they are 10 bolt (steveken was selling rs6 6mt conversion kits with a working flywheel)


just saw the latest post, from what I've found no Audi V8s have ever been sleeved (this will conflict with information in the 4.2 build thread but I've found no evidence). The motors have always been Alusil.

Another option to consider if you wanted to build a bhf yourself would be to get the bores nikasil coated, may give you more options for pistons (alusil limits you choices).

[rotorhead24]

The car is also not technically street legal. I didnt need it to be.

EXACTLY MY THINKING. And props on dropping 600 while still adding a cage. However, I do hope to retain most of my interior by adding alot of boost with my build. A back seat delete seems to cause alot of butt hurt controversy these days when trying to compare rides these days lol.

[RX-Heven]

Put a rotary in it ;)
That will give you plenty of room for all peripheral systems, save weight, and make the power you want.

[rotorhead24]

I have wandered outside Audizine to find the best info in a single thread that has resolved nearly all my questions and hopefully others you may have too:

http://www.motorgeek.com/viewtopic.php?f=10&t=37659

[EUROSWAGR]

Members that have been around and have explored built options know about that thread, in fact it's probably linked in past threads about the same topic. I guess it is a good link for new users to visit though.

[rotorhead24]

To summarize this thread:

The AVP code: 32v belt timed, 4.2, drive by cable, non vvt engine has been Audi's longest running (mileage) non oil burning V8 engine. I have read multiple time that they reach 250k + miles with good maintenance.

The AVP has been used in success in the DTM circuit, thanks to the lack of Alusil or whatever its called, that turns every post 1995 4.2 over 100k mi into a sand paper lined vagina. That deseves a class action lawsuit if you ask me.

[FastEddie]

I know it would be expensive but I think the new 4.0 TT setup in the new S6 and S7 MAYBE could fit. The turbos sit on top of the engine in the back. Something worth looking into! Plus those motors are new and haven't really been played with yet.

[EUROSWAGR]

I know it would be expensive but I think the new 4.0 TT setup in the new S6 and S7 MAYBE could fit. The turbos sit on top of the engine in the back. Something worth looking into! Plus those motors are new and haven't really been played with yet.

I hope your an electrical engineer or have a very strong background in electronics if you decide to take on that task.

[BCsniper]

if I were in your shoes I'd do a stock RS4 or RS6 motor, or a built bhf from JHM. There should be an RS6 motor for sale in the classifieds (AudiA4_20T),

The RS6's seem to be getting more and more attractive these days. A huge twin turbo V8 and yet the prices for them continue to decline, finding them for $20k seems to be normal. There's one for sale by me for $18-19k. I wouldn't necessarily want to own one, but I could see them being used for donor engines for other builds more often now.