Audi A5 Forum & Audi S5 Forum banner
1 - 19 of 19 Posts

·
Registered
Joined
·
457 Posts
Discussion Starter · #1 ·
It's finally coming!

According to [email protected] their S5 has been undergoing development at GIAC for over a week now and should be ready in 2 weeks or so. From past pricing, I'm expecting it to be well under 1k USD w/ comparable gains to anything currently available on the market.

I want a custom tune!!!
 

·
Registered
Joined
·
198 Posts
What HP bump should we expect with ECU GIAC + GMG exhaust? Enough for 400 hp?
IMHO, doubtful. The FarnbacherLoles custum tune on my car gave me 25HP on top of what gains I already had with the Milltek exhaust. I would guess 385-390HP tops with those mods.

Just my $.02...
 

·
Registered
Joined
·
39 Posts
I assume that it will be a self-installable module or ECU update vs. sending your computer or even worse the whole car to GMG. Can anyone confirm.
 

·
Registered
Joined
·
457 Posts
Discussion Starter · #6 ·
I assume that it will be a self-installable module or ECU update vs. sending your computer or even worse the whole car to GMG. Can anyone confirm.
I believe, like all other places, involves removal of the module and sending it to GIAC or GMG for the reprogramming. Bringing in your car in for the retune will also accomplish the task at hand.
 

·
Registered
Joined
·
82 Posts
you just need to find your local dealer. champion does it if anyone in south florida is interested. they did my 225TT and it was great (2 hour turn around).
 

·
Registered
Joined
·
536 Posts
IMHO, doubtful. The FarnbacherLoles custum tune on my car gave me 25HP on top of what gains I already had with the Milltek exhaust. I would guess 385-390HP tops with those mods.

Just my $.02...
You are most likely correct, but I have a remaining question as to why the GIAC chip will be unable to rise the HP by a greator amount... Now, I heard that the S5 engine is simply a detuned RS4/R8 engine, which produces 420 HP, and not just an upgrade to the original Audi 4.2 liter V8 found in many current and past Audi cars. Now, if this is true (that the S5 engine is a detuned RS4 engine), then the most cost efficient way to detune it would be to modify the ECU, constrict airflow to the engine (which was how the Benz E55 AMG made less HP than an SL55 AMG), and to add more back pressure (I believe that is the correct term) to the exhaust, all or any of which Audi could have used to detune the 420HP RS4 engine to the 354HP S5 engine. Now, if this is true, then a correct modification to the ECU, coupled with a free flowing exhaust and air intake, should bring the car to around the same 420HP that the RS4 has. But you, and most other members belive that, even with these modifications, the S5 engine will most likely not hit 400HP, let alone 420HP.

So, my question is, did GIAC just not put enough effort into modifying the ECU to something similar to the RS4 ECU (the same also, or possibly, going for companies who manufactur aftermarket exhausts and air flow intakes), or is it that Audi did more drastic and mechanical modifications to the RS4 engine to provide 66 less HP, such as changing the pistons, engine cooling elements, spark plugs, ect. (basically, any modification to the internals of the engine such that it would be very cost ineficient/expensive for a S5 owner to modify the engine to the original RS4 spec), or maybe is it that what I have heard stated here, and on other websites/reviews/videos/forums, is wrong, and that the S5 engine is just an evolution/tweeked version of the original 4.2 Audi V8, such that they took a recent 4.2 V8 from a standard A6 or A8 V8 and then modified it to produce a more powerful engine, one fit for a 4 pass S coupe, and that the S5 engine is not a direct descendent of the RS4 engine (and incase you are wondering; yes, I know that the RS4 engine is also based on the original 4.2 Audi V8, albiet heavily modified, but there is a difference between Audi taking the specs of an RS4 engine as a starting point/base, and detuning it for the S5, versus Audi taking a current, standard 4.2 V8, such as from the current A6, and just tweeking the engine internals, ECU, exhaust, airflow intake and other things, like adding direct injection, in order to create a more modern/powerful/sport orientated engine beffiting to the S5, being the sport version of the A5 4 pass coupe)?

Cliff Notes (although I recomend reading the entire post, as it contains a more detailed question that I would like the response to): So if, as I heard here and many others places/forums, as well as reputable articles/review of the S5, the S5 engine is a detuned version of the RS4 engine (such that Audi took the blueprint of the RS4 engine as a starting point, and then just tweeked it), then why won't an ECU upgrade from a reputable company, coupled with a new exhaust, engine air intake, and maybe some other relativly inexpensive engine mods, raise the S5's engines output to the same 420 HP that the RS4 engine produces, or at least above 410 HP?
 

·
Registered
Joined
·
135 Posts
The S5 engine is a detuned version of the 4.2L FSI V8 that powers the RS4 & R8. My understanding is that the engine internals are different, which doesn't allow the S5 engine to be a high rev engine. The CR is also lower than the high rev version. Without the high rev capability, it's doubtful that you'll be able to match the output of that engine. I do think that you'll be able to get close to 400 bhp, but it may take cams, which woulld be a very expensive option, if it becomes available. The good thing about the engine not being a high rev version is the higher mid-range torque that the engine produces compared to the high rev version.
 

·
Registered
Joined
·
536 Posts
The S5 engine is a detuned version of the 4.2L FSI V8 that powers the RS4 & R8. My understanding is that the engine internals are different, which doesn't allow the S5 engine to be a high rev engine. The CR is also lower than the high rev version. Without the high rev capability, it's doubtful that you'll be able to match the output of that engine. I do think that you'll be able to get close to 400 bhp, but it may take cams, which woulld be a very expensive option, if it becomes available. The good thing about the engine not being a high rev version is the higher mid-range torque that the engine produces compared to the high rev version.
Thanks for the response. But why can't an ECU mod change the S5s reving capability to that of the RS4? I mean, what internals that you are talking about would prevent an ECU mod (the ECU being the brains that controls the engine, including the rev range) from raising the rev range to match that of the RS4 engine (and, pardon my mechanacal knowledge, or lack thereof, but what does "CR" stand for)?

Also, this discussion led me to another quick question. Is the B7 S4 engine also based on the RS4 engine, or is it based on previous 4.2 Audi V8s, like the B6 S4 (I belive B6 had a V8 and not the turbo 6, but I could be mistaken as Audi may not have changed the code for the A4 when they gave it a refresh/update at around 2005) or other discontinued Audi models?

Thanks
 

·
Registered
Joined
·
1,295 Posts
Thanks for the response. But why can't an ECU mod change the S5s reving capability to that of the RS4? I mean, what internals that you are talking about would prevent an ECU mod (the ECU being the brains that controls the engine, including the rev range) from raising the rev range to match that of the RS4 engine (and, pardon my mechanacal knowledge, or lack thereof, but what does "CR" stand for)?
We had this discussion fairly in-depth in another thread:

http://www.a5oc.com/forums/showthre...index.html?t=4044&highlight=compression+ratio

CR stands for 'compression ratio'. In a naturally aspirated engine (like ours), the only way you raise this is to reduce how much volume is in the cylinder when the piston is TDC (top dead center). This is accomplished by either changing the distance between the block and the head (i.e. running a thinner head gasket or milling down either the block or the head surface), by changing the stroke (i.e. running a longer piston rod so that it travels further), or by replacing the piston with one of a different shape (the top of the piston is not perfectly flat, it has a dome shape to it which can be cast/forged differently to affect compression). Any of these options requires you to disassemble the engine, replace parts, do machinework, and put it all back together again. Not cheap, not easy, and not quick.

As for the revs, you are most likely looking at getting longer duration camshafts, which waste a bit more air in low revs, but allow the engine to operate more efficiently at higher revs. You also have to make sure the fuel system is up to par, and of course the ECU has to be mapped that high up in the rev band. As complex as it sounds, this route is far easier than changing the compression ratio -- HOWEVER... cams don't give you free power, they are just moving your powerband around, so if you gain in one place (i.e. at 8400 rpm) you will likely lose power somewhere else. This is confirmed by comparing an RS4 to an S5 torque curve (S5 produces usable torque much sooner). Camshafts are not terribly expensive or difficult to install depending on how accessible the heads are (I don't have my S5 yet, so I can't tell you).

With an ECU alone, you can probably raise the rev limiter to 8400rpm just like the RS4, but it's doubtful that you will make power at that RPM, so it would be engine strain for no reason.

-Ray
 

·
Registered
Joined
·
536 Posts
I believe, like all other places, involves removal of the module and sending it to GIAC or GMG for the reprogramming. Bringing in your car in for the retune will also accomplish the task at hand.
Because of warrenty issues, that makes me less likely to order the GIAC ECU upgrade. Although I know that GIAC is a very reputable manufacur or ECU updates/reflashes, I would much rather buy a piggyback ECU mod, like the ECU chip/mod from Vishnu Tuning for the BMW 335i (and all other BMWs with the same 3 liter twin turbo gas engine). This is partly because I find it extremly difficult to bring myself to pay 2 grand or so for the GIAC upgrade, as it is basically just a data file that contains a coding/software upgrade for the ECU (being something that I could probably fit on an old 1.4 MB capacity 3.5 floppy disk), compared with paying that 2 grand to get something phisacally tangible, as it is usually a new/custom manufactured chip with encoding built into it's memory, enclosed in a box that connects to the ECU via a data cable (and yes, I know that thinking that way isn't very rational, as much of the cost of the GIAC ECU reflash is because of high r&d costs, due to weeks, or even months of programing the original ECU by a team of multiple specialized employees who command relativly high salaries for their knowledge and experience, as well as the cost of using/borrowing an S5 for weeks of testing. Simalarly, this is also the similar reasoning behind the high costs of some perscription medication as well as PC/Mac software/programs, but for me, buying the GIAC reflash is like paying 500+ bucks for an amazing game that will keep you busy/satisfied for months, especially since you most likely have the option to download the game for free, albiet illegally, which makes me wonder if it's possible to do the same for the ECU reflash data? Although I would never do that, as it's not only illegal, but seriously hurts the finances of a wide range of employees in that company, many having the responsibility to support a family, which is why I always buy my music, movies, TV shows and games legally, which is why I already spend too much on media and software, plus I keep needing more space to fit all the boxes the CDs/DVDs came in, lol. Not to mention the issue of installing the data on the ECU, which would nesessitate purchasing or borrowing, if you are lucky, expensive equipment, and also because if you make a mistake, you end up with a nice/big 60 grand paper weight, LOL). But the main reason why I like piggyback ECU mods vs. a flashed ECU is because of warrenty reasons. I know that GIAC, as well as most people in the industry, state that the changes these mods make are "undetectable," but if something seriously goes wrong with your engine, as in the engine is unreparable or the costs to fix it get close to, of go into the 5 digit range, then Audi, like most auto makers, especially ones whose cars are often modified by their owners, will dispatch an employee whose sole purpose is to find any reason they can so that Audi can deny warrenty coverage, and I am sure that one of the steps they they take is to download all the software on the ECU, and if they compare that data to what a stock ECUa data and find major changes, like an engine or fuel renmap, being something similar to a GIAC ECU flash/remap and not a minor change, like a simple VAG-COM mod, then they will deny covering the cost to fix the car, which can be 10s of thousands, which is especially worse for people like me who will lease their car, as they can't return the car to the bank in that condition, so you are forced to pay a HUGE bill on a car that you not only don't even own, buy will return it back to the bank in a few years, or possibly months, unless you pay the expensive buy-out cost at the end of the term which you most likely have to pay in one big payment! And yes, if for some reason you can, due to US warrenty laws, prove, with practically irrefutable evidence, in a court of law that the ECU mod had nothing to do with the damage to your car, then the car maker will be forced to foot the bill, but that is only really possible for damages that don't involve the engine, like some transmition problems or suspension problems, but not 90%+ of all possible engine problems, which are usually the most expensive problems to fix. I also know that GIAC keeps a version of your original ECU software in their databanks, as well as giving you a CD with a copy of that same data on it, but that means that after your car breaks down and is sent to Audi, you have to tow the car to a local performace shop that can do ECU modification (in some areas the closest one will be hours away), hope the car can still turn on to accessory power mode, and give a reason to the Audi dealership as to why you need to tow the car and then bring it back in a day or so (as long as you remembered to tell the dealer to not diagnose or start fixing the problem), and the whole process can be very costly and time consuming, not to mention the cost of reflashing your ECU once the dealer/repair shop fixes your car. Now, if you have a piggyback ECU chip/mod, and your engine brakes down on you, or if you think your engine has broken down or is at least possibly part of the problem you are having with the car (and the problem being one that you need to bring/tow the car to the dealership, then, even if you are stranded on the side of the road (as long as you have the proper tools in the car, which you should, then all you need to do is pop open the hood and ECU cover, remove the piggyback chip and anything that relates to the piggyback chip, like the harness for the chip and the wires that connects the chip to the ECU, put the ECU cover back on (and btw, you need to make sure that you are doing this carfully so that it doesn't look like the ECU box has been opened or tampered with), close the hood and then call AAA for a tow, or drive the car in limp mode to the dealer/repair shop, and then, as long as the ECU box doesn't look tampered with, as previously mentioned, your ECU mod is truly 100% undectable, and when you car is all fixed, you can drive it home and then take 10 minutes to connect the piggyback chip back to the ECU... it's easy as pie, and you are basically guarnteed to never have your warrenty denyed, unless you are an idiot and forget to remove it (or forget to always leave the tools neccesary to remove the chip) or were too lazy to install the chip yourself, in which, if you were smart, at least take 10 minutes out of your day to watch your local performance shop install it so you know how to take it out. It is because of these important reasons why I don't understand why some great ECU tuining houses like GIAC refuse to change how they mod the ECU to a piggyback chip, or at least give the customer the option to have their ECU flashed, or charge a little bit more for basically the same remap but on an easially removeable (and installable) piggyback chip, which I, and many people would definatly pay for, not only for warrenty reasons, but also because of time issues, as you will have to wait for up to a week, unless you have a GIAC distributed near you, for your ECU to be removed, shipped, remapped by GIAC, shipped back and then reinstalled, and in the meantime, your car can't even turn on (and it may even be dangerous to even try to turn the car on, although most likely not).


This part is very off topic... (but I quickly wanted to mention it):

And yes, I know this post, and the one I wrote just previously, are probably very long (I typed this all on my iPhone, so there is no way for me to guage how long it will be until I post it) but I was given some utterly devistaying news this morning, and writing all this helpt my mind to temporarily forget about it, plus, you don't have to read it ;) . But seriously, I want to aplogize if this, or any of my previous long posts have annoyed or bothered any of you. :) I will do my best to keep the word count down in the future, LOL.
 

·
Registered
Joined
·
198 Posts

·
Registered
Joined
·
198 Posts
I do think that you'll be able to get close to 400 bhp, but it may take cams, which woulld be a very expensive option, if it becomes available.
Upgraded cams are under consideration at FarnbacherLoles but I need to follow-up with Kip/Peter to see where they are in the decision process.
 

·
Registered
Joined
·
2,335 Posts

·
Registered
Joined
·
135 Posts
Thanks for the response. But why can't an ECU mod change the S5s reving capability to that of the RS4? I mean, what internals that you are talking about would prevent an ECU mod (the ECU being the brains that controls the engine, including the rev range) from raising the rev range to match that of the RS4 engine (and, pardon my mechanacal knowledge, or lack thereof, but what does "CR" stand for)?

Also, this discussion led me to another quick question. Is the B7 S4 engine also based on the RS4 engine, or is it based on previous 4.2 Audi V8s, like the B6 S4 (I belive B6 had a V8 and not the turbo 6, but I could be mistaken as Audi may not have changed the code for the A4 when they gave it a refresh/update at around 2005) or other discontinued Audi models?

Thanks
The strength of the rods determine what the maximum RPM the engine is built for. If the S5 doesn't have the same rods as the RS4, it won't be safe to rev it as high as an RS4 engine. Also, the camshafts & intake manifold are most likely tuned to make power at a higher RPM in the RS4 engine vs. the S5 engine. You could certainly mechanically rev the S5 engine to 8,000 RPM if the rev limiter were removed, but it wouldn't necessarily make more power as RPM increased if the engine wasn't tuned for maximum airflow at those RPM's. If you look at a stock dyno graph for an S5, I'll bet that power starts dropping just prior to 7,000 RPM's.;)
The B7 S4 engine is the non-FSI 40v 4.2L V8 (which the FSI engine was derived from by placing the fuel injector where the center intake valve used to be).
 

·
Registered
Joined
·
135 Posts
There are a substantial number of differences between the 4.2L in the S5 and the RS4. The only things they really have in common are (1) displacement and (2) they are installed in Audis:

http://www.6speedonline.com/forums/audi-s-s4-s6-rs4-rs6/103884-audis-4-2-v8.html

Due to all of these reasons, it is not as simple as just increasing the redline to make more HP, IMHO.

Some very good info in that link, thank you. Apparently, there are many differences between the S5 & RS4 engine. They did, however, incorrectly state that the S5 engine is a non-FSI engine. I'm pretty sure that the S5 & Q7 engines are basically the same (although Audi's website lists the CR's as being different).
I think that close to 100 hp/ltr may be obtained w/the S5 engine without the high rev capability.
A lot of the VW R32 guys are getting close to that (300-310 bhp) naturally aspirated & that engine isn't even FSI.
 

·
Registered
Joined
·
1,184 Posts
This part is very off topic... (but I quickly wanted to mention it):

And yes, I know this post, and the one I wrote just previously, are probably very long (I typed this all on my iPhone, so there is no way for me to guage how long it will be until I post it) but I was given some utterly devistaying news this morning, and writing all this helpt my mind to temporarily forget about it, plus, you don't have to read it ;) . But seriously, I want to aplogize if this, or any of my previous long posts have annoyed or bothered any of you. :) I will do my best to keep the word count down in the future, LOL.
Even your apology was a full paragraph......:D

Alwin,

Are you driving up to get yours done? If so let me know and we can get it done together. Maybe we can get a price break, but minimally we can talk shop while we wait.
I am very seriously considering going full GMG exhaust/downpipes as well while i'm at it....
 

·
Registered
Joined
·
457 Posts
Discussion Starter · #19 ·
Even your apology was a full paragraph......:D

Alwin,

Are you driving up to get yours done? If so let me know and we can get it done together. Maybe we can get a price break, but minimally we can talk shop while we wait.
I am very seriously considering going full GMG exhaust/downpipes as well while i'm at it....
I want a custom tune, so yeah, I don't mind bringing it to GMG/GIAC directly for one. You're cool with the oval dual tips vs. the quad tips?

I really wanted their exhaust too, but the tips killed it for me...can always saw those off and replace them with quad tips, but at that juncture of the exhaust system, getting it welded seamlessly and lined up perfectly/evenly on both sides becomes a high-risk poker game. Their system is also the only system I haven't tried in full yet too hahaha. I'm happy with their downpipes though, and I still think the Milltek tips are the nicest looking compared to anything else available on the market for the S5.
 
1 - 19 of 19 Posts
Top