What is the highest safe boost levels on B9 S4 with stock fuel system and engine

[FrankTsui]

Hi everyone

Thinking of tune the car and wanted to know the hardware limit of EA839 engine.

from the source:https://motor-car.net/vw-engines/item/20039-vw-ea839 indicates the highest turbo pressure is 2.5 bar (absolute) , however I logged my stock S4 that the boost pressure spikes to 2.2bar (absolute) and taper to redline. And also logged my friends' stage 2 S4 which pike to 2.85bar and 2.7 with different tune brands.

Just wondering what is the safe turbo pressure limit of the stock engine and fuel system? Tuners told me the engine could do stage 3 without replacing any engine hardware except turbo and could do more than 3 bar (absolute) pressure without sacrificing anything.

many thanks!

[oesman]

Just wondering what is the safe turbo pressure limit of the stock engine and fuel system? Tuners told me the engine could do stage 3 without replacing any engine hardware except turbo and could do more than 3 bar (absolute) pressure without sacrificing anything.

I don't think there are easy answers here. I doubt we're going to get a specific number that we all agree is perfectly safe and a number that's dangerous. Obviously more boost creates complications from heat, pressure, etc... Furthermore, it's not just how much boost pressure, but also how efficient the turbo is and how much total air you're putting in there in terms of mass (M = V * d). You might only be adding say 0.3 bar but the bigger hybrid turbo is putting more air mass into the engine. In simplest terms 3 bar through a drinking straw isn't the same as 3 bar through a garden hose. More air mass results in more power from combustion with adequate fueling. So ultimately it's not just the pressure you're worried about, but weather the engine will handle the extra power and if the fuel system will manage the demand. How safe that is will be complicated by mechanical tolerances, existing engine wear, fuel system wear, environmental conditions, maintenance, etc...

Stage 3 at 3 bar including atmospheric pressure seems about right, I see right around 28 psi above atmospheric (I'm at sea level) on my TTE 710 with 034's Stage 3 E85 tune. The general consensus from tuners is this is safe on the stock block, but I doubt you'll find anyone willing to actually warranty that. So far there are a good amount of Stage 3 cars and we're not seeing engine failures left and right. Ultimately the more you modify the car the more risk you take, this is one reason some people will buy a $100k+ car vs. putting $20k in mods into a $40k car even though the modified car might turn out just as fast or faster.

[AldermanToffee]

I’ve ran just shy of 3.5 bar absolutely and it has been fine.

I don’t think anyone has really found a limit yet. That 3.5 bar was on a rather large turbo bang on within its max efficiency, so very different to a smaller turbo absolutely screaming of course.

[FrankTsui]

Thanks for your interpretation. Turbo pressure looks very comprehensive and therefore cannot be defined with just a single number. Learnt really a lot! Thank you again!

[FrankTsui]

Yeah 3.5bar absolute looks pretty scary but I have been told that the engine uses EA825 parts and therefore could make incredible horsepower.
May I know how much horsepower do you make now with 3.5 bar?

[AldermanToffee]

Yeah 3.5bar absolute looks pretty scary but I have been told that the engine uses EA825 parts and therefore could make incredible horsepower.
May I know how much horsepower do you make now with 3.5 bar?

Yes, there is crossover between the EA839. The EA839 is essentially the "newer gen" engine that subsequent engines (such as the EA825) are based on.

I was making ~600whp on 3.5 bar on 93 AKI and 12 degrees of timing. So quite a "tame" tune.

I believe the more aggressive E60/E70 tunes from 034/IE run around 3.2 - 3.3 bar with 18-20 degrees of timing and make slightly more. Maybe closer to 650whp? This is on a smaller turbo also.

[FrankTsui]

WOW!! 600 whp that is amazing! have you replaced the turbo? my stage 3 friend told me the EA839 could do stage 3 with only turbo, pressure sensor and intake+downpipe replacements.

I talked to a tuner that I just want a "stable" tune and don't require fast 0-100km/h acceleration. I'd like to race the car in mountains and tracks and he says 2.6bar absolute with 12 degree of timing sounds good for my needs (98 octane gas). I think with that setting it could only make say 320 whp?

[AldermanToffee]

WOW!! 600 whp that is amazing! have you replaced the turbo? my stage 3 friend told me the EA839 could do stage 3 with only turbo, pressure sensor and intake+downpipe replacements.

I talked to a tuner that I just want a "stable" tune and don't require fast 0-100km/h acceleration. I'd like to race the car in mountains and tracks and he says 2.6bar absolute with 12 degree of timing sounds good for my needs (98 octane gas). I think with that setting it could only make say 320 whp?

Yep, big turbo and now building the engine too. Stage 3 is indeed turbo, intake, intercooler and optionally a downpipe. If you’re running over 3 bar you will needed a 5 bar MAP sensor.

Stock turbo can run 2.6 bar no problem at all. I think you might be able to squeeze around 2.7 bar out of it. Completely depends on your altitude but 320whp is more than doable.

Sorry, can’t give you a better estimation of power levels on stock turbo as it isn’t something I’ve looked into much to be honest.

[FrankTsui]

Yep, big turbo and now building the engine too. Stage 3 is indeed turbo, intake, intercooler and optionally a downpipe. If you’re running over 3 bar you will needed a 5 bar MAP sensor.

Stock turbo can run 2.6 bar no problem at all. I think you might be able to squeeze around 2.7 bar out of it. Completely depends on your altitude but 320whp is more than doable.

Sorry, can’t give you a better estimation of power levels on stock turbo as it isn’t something I’ve looked into much to be honest.

No probs at all mate! Thank you so much for your info!

There are some stage 2 S4 which run 2.85 bar absolute without any probs. And the logged APR stage 2 and found APR use 2.7 bar+. I think stock engine can hold at least 3 bar+ with proper timing and turbo's limit should around 2.9 bar I guess? since the stock pressure sensor supports 2.99 bar

[AldermanToffee]

No probs at all mate! Thank you so much for your info!

There are some stage 2 S4 which run 2.85 bar absolute without any probs. And the logged APR stage 2 and found APR use 2.7 bar+. I think stock engine can hold at least 3 bar+ with proper timing and turbo's limit should around 2.9 bar I guess? since the stock pressure sensor supports 2.99 bar

The issue is the turbo is being massively over spun at such high boost levels. It might work but it would not be efficient or sustainable

[oesman]

The issue is the turbo is being massively over spun at such high boost levels. It might work but it would not be efficient or sustainable

Yep and to piggyback on this a big part of the problem with spinning a small turbo very fast is heat. Result is harder to manage air charge temperatures, less timing advance, and more detonation risk. Furthermore sure you might hit a bar/PSI number, but as we were discussing earlier mass is what matters. Hot air expands and is less dense, the air charge won't have as much mass. It's all about cramming as many grams/pounds/whatever of air in there not really pressure per se. We just correlate boost levels with mass because it's an easier concept to grasp, more pressure, more air mass, but it doesn't linearly translate in real life when you're outside of efficiency of the compressor.

[Speedster00]

cool discussion. I know of a guy named mario with M2 motorsports thats tuned a few full frame turbo builds at 700+ wheel and hasnt seem to found the limit of the engine. 034 admits in a recent weekly video they haven't found the EA839 motor limit either.

Im stage 2 EPL with a stock DP. Apparently that was the only tuner that would let you go stage 2 on a stock DP. I dont want the noise or emissions hassel with a gutted cat so Ill stick with my EPL tune. Stage 3 would be a blast but I dont want to mess with the DP/Emissions, ect..

[oesman]

I know of a guy named mario

Heh well thats going to open up a whole can of worms since he was also the guy apparently posting fake Dragy screenshots.

034 admits in a recent weekly video they haven't found the EA839 motor limit either.

I recall them saying the rods were the main weak point, but I think other than that no one's really found a hard limit yet and 034 said they haven't had a failure, but it's their assumption based on prior experience. They're selling Pauter rods for the EA839 already on their site.

Not sure who's rods AldermanToffee is going with, but he was telling me he's doing pistons and rods in his new engine, since the old one sadly melted a piston when an injector crapped out.

[AldermanToffee]

I’m using Italian RP’s Rods and Pistons in mine.

[Speedster00]

Heh well thats going to open up a whole can of worms since he was also the guy apparently posting fake Dragy screenshots.

Oh dang! I did not know that. I will say the guy posted all the builds and pictures but would never answer questions.

[oesman]

Oh dang! I did not know that. I will say the guy posted all the builds and pictures but would never answer questions.

Yea something about a screenshot of a Dragy he cropped so you could only see a bit of it and claimed was a B9, but then people found it the uncropped version and it was some other guy's M3 lol. If you're in the b9 discord, it's in the chat history.

[AudioPAS4]

What were you getting at Stage 2 034? My VAdPro is hitting 8, but i dont thing thats right. Thoughts?

[John@DEADBEEF_DynoSp]

People wondering why they blow up only need to read this thread with its unicorn timing and boost numbers on inadequate hardware.

[AldermanToffee]

People wondering why they blow up only need to read this thread with its unicorn timing and boost numbers on inadequate hardware.

The weekly Facebook posts of engine failures on tuned vehicles are doing a very appropriate job at that.

[S4James]

this is why im sticking with a 93 tune until i can see some progress here.