I've seen many people running at, according to several people, the maximum efficiency of 12psi while producing very good numbers. But I have also seen and heard of people running 14psi on stock turbo, not hybrids. Can anyone report what kind of numbers they are getting or some of the factors that may play into this? I've heard things such as after 12psi the air is too hot to produce power. I'm looking to get the most HP out of the stock turbo possible so I'd like your opinions and experiences.

 

I'm running an S5 stock turbo in my S4 TurboVert. After dropping in a new S4 TII engine and then right after correcting a few vacumn leaks, my boost that would prior max out at 9 lbs jumped to 14 lbs. This while accelerating onto the freeway. As soon as I could my boost controller cranked it back down as I don't like exploded engines.

Point being, you do not want to go much beyond 9 lbs of boost unless you significantly upgrade your fuel and ignition timing management with a Haltech or the like. Or engine go POP!!

So to answer your question, absolutely you can get 14lbs of boost from a stock turbo. But don't go there unless you upgrade the sophistication of your engine management first.

 

I'm tuning on Rtek 2.1 and making adjustments currently on my 12psi setup. Timing corrections have been configured, now I am just logging fuel adjustments. I just want to know what would happen on the turbo's end! I'm worried if I push it too hard that I'm going to be rebuilding turbo's here all the time.

 

The stock turbo map isn't documented as well as aftermarket compressors, so it mostly draws on anecdotal evidence. 12 psi is not the efficiency peak, it's about where the tradeoff between airflow and heat production is acceptable. FMIC's and water injection can help tame your intake temps, but every setup and situation is different. Since you have a RTek 2.1, log your intake temps at 12 and 14 psi and post them up. Work your way up as long as your IAT's are safe.

Anecdotally, turbo life seems to be shortened by running that hard. How long do you need it to last?

 

I've just rebuilt it, I don't want it running beyond what it's supposed to and drastically reducing it's life. I'll try and do some logging tonight to post up some temps. I'm running a Greddy FMIC so this should drastically reduce the temps over stock tmic correct?

 

I ran 14psi for a while. After 2 blown turbo's, I'm down to 10psi.
The turbo will only last a year or two at 14psi. Don't forget t port your wastegate to prevent any spikes. Spikes at that range could pop the motor.

The car definitely has more kick in the pants power at 14 than 10psi. Local people have hit high 13's in the 1/4 mile when running 14-15psi. I've run a 14.2 at 10psi.

The stock top mount and 14psi is just asking to grill steaks on that intercooler.

I have a NPR fmic and the car is fine.

Fuel mods are Walbro, 720 secondaries, and rtek 1.7

 

I ran 14 lbs, turbo didnt last long and neither did the engine.

 

Measure your IATs between 10 PSI and 14 PSI and you'll never run 14 PSI again. At that point you're just heating the intake charge so much as you are way out of the compressor efficiency.

 

But what's if you use pre turbo water injection?

 

why spend all that money trying to get more out of a stock turbo when you could just as easily be putting that money into a better turbo?

on a side note, I was wondering if there's a manifold that's like the greddy cast one but fits like a stock s5 turbo manifold? I do t want to redo my fmic pipes but I keep cracking manifolds and want to find something better than tube steel

 

I'm currently running 12 Psi on the hybrid maxing out my wastegate. the wastegate actuater is ported so the power feels really good and solid. no issues so far tuned on haltech. 1600 secondaries

 

I have, but I'm on my second turbo now. You can run 12s in the quarter mile with the stock turbo. From my experience, running it at 14-15 pounds will be faster than 12.