How far can you push a mostly stock S5 TII?
 

I was thinking, as I feel I am getting too used to the power I have now, which I dunno how much it really is, boosting around 11-13psi, 0.9 bar anyways, Racing Beat REV TII exhaust, metal intake from air filter to turbo.

If I say, added an Rtek 2.1 (due to the value compared to price vs. a proper standalone), bigger injectors (720cc would be enough I guess), stuck with the stock turbo, maybe a fuel pump as well...

What could I be looking at staying on the safe side of AFR 14.7? If Racing Beat's numbers are correct, right now I am looking at 260bhp @ 0.9bar. Probably more or less, no way of testing this, but with my list I would bet around 300-330, or am I far off?

Btw, for the summer I will probably get all these mods done, and get money and time to go to a dyno as well, to confirm my numbers, but a theoretical max with 720cc inj, Rtek 2.1, RB Rev TII and a bigger fuel pump, that is my main question.

You need a bigger turbo.

Lower the boost to stock levels before you blow the engine. 11-13 psi is FAR from safe with a stock fuel system.

I can push a stock T2 about 50 ft.
After that, it's AAA.

Tune your car before she blows. That can't be safe.

Depends on your stamina i guess.. :lol:

All joking aside, stock turbo will not give you more then 300fwhp

What if I said that she did not run lean now, but is borderline?

What is borderline to you? I hope this is not the same car with erratic idle that you have. Bottom line is you are running too much boost for the stock fuel system, but if you have that need for speed, you can always port it when it blows soon.....

Justin

14.7 afr? That's wayy to lean under boost

14.7 is the border called stoichiometric. But as for borderline, my numbers are below 14, 13.5-ish. It is borderline, yes, but it won't kill my engine.

And yes, what gas do you fill on your car? What gas SHOULD you fill on your car? I fill RON 98, that is 93 AKI where your regular is 91 RON 87 AKI. That helps a bit as well I bet. Mentioning this because many places in the US there is a lack of anything above regular, and if lucky, 95 RON 89 AKI is the highest you get.

14.7 is not a magic number, that is pretty damn lean under 11lbs. of boost. 13.5 is not borderline, that is lean as well. You WILL blow your engine running the way you have it now. You need larger secondaries AT THE LEAST, and a better fuel pump.

That being said, you aren't going to push the stock turbo past 11lbs. safely and you aren't going to get the engine pushing more than 260-280hp with the stock turbo.

You need bigger injectors, management, and a larger or hybrid turbo to get your power goals. Now, stop driving your car like that and read.

You're stock top mount intercooler also can't cool the stock turbo at 12+ psi either.

At this point, your higher octane gas is probably the only thing keeping it running. Your setup is not considered 'safe', resulting in this stream of replies concerned for the life of your engine.
FYI most places here have 91 AKI readily available, so the tuning advice here is pretty accurate for you.

In a laboratory, yes, a 14.7 afr is the most efficient way to turn gasoline into water and carbon dioxide. Inside a rotary engine combustion chamber, high egt's and detonation potential require a much richer mixture. Tuners that have generously shared their results have used much richer afr's than you are doing.

Hahaha, instantly everyone comes in the thread and says turn down the boost now or it will blow up. He responds with. Its fine.

Why ask questions when you don't listen?

Seems like a common theme lately. It amazes me when these threads pop up when there's so much info on the forum detailing exactly how to build a safe setup. It's literally as simple as putting together a shopping list based on forum threads and installing parts to make an engine/turbo/fuel/ecu setup that has been proven safe and successful numerous times.

there are very few cars in the world that run Stoichiometric air/fuel ratios under full throttle. your full throttle mixture should be in the 11's, if not even a little richer.

13.5 is leaner than most people would feel comfortable running an NA!

i hope you have a tow service.

you need to do a little more research on force inducted engines, particularly rotary force inducted. you seem to comprehend everything except the most important, which is target AFRs for a combustion engine. a rotary will give no hint of a problem until it is too late when lean mixtures are taken into account. 11.5:1 AFR is about your peak target above 10psi, below that you can get by a little leaner. running beyond 15psi pig rich before ignition breakup occurs, usually a target of 10.5-11:1 AFR.

14.7 even with the smog pump, it still isn't a magical fuel, far from it. turbo cars could run 87AKI but were limited to factory boost which was borderline for that fuel, 91-93AKI(our "premium" pump fuels) bumped up the auto ignition table a bit for more boost BUT the same AFR tables had to be used. octane should be looked at as a point where the fuel is going to combust without spark, if you run lean enough all fuels are equal and will detonate, causing severe damage.

the air injection from the smog pump generally accounts for about 2 full AFR points(each smog pump has slightly different efficiency due to wear), so your AFRs are likely high 12's, pushing the engine into a shallow grave each time you press the throttle.

mazda's factory boost cut level was aimed at the noob owners who would unknowingly run 87AKI.

hopefully you read these replies before it's too late.

Those Apex seals are gona look like bananas if you keep running your A/f that lean.

im almost in the same situation, but i wanted to know whats the max boost you can run a completely stock s5 t2 at. i capped it at 9 pounds on my boost controller, im pretty paranoid about it and wanted to know if i could run any higher.

10psi is straining the limits of the stock fuel system as well as the rather aggressive timing maps.

upgrade turbo. stock turbo is a peashooter. doesn't make ideal use of the rotaries powerband. chokes out during the high rpms, and maxes out at about 11-12lbs anyways.

if you want to run stock, pick up the rtek, wideband, bigger injectors, fuel pump upgrade. stock tmic is fine for these levels.

and do some research on afr's.

i have two 820cc low imp. injectors i have no need of.... wink wink.

While this is up, what's the limits of the stock injectors? I'd like to be up around 10-12psi but need to start figuring out my limits as far as fuel. It has a walbro pump but stock injectors. It also has a microtech lt-10s, bnr stage 1 turbo, stock tmic and several other things that are probably irrelevant to the question. I'm trying to not go to the point of.....vmic and new injectors just yet but would like to be able to go higher than 8psi.

there is no set limit, the easier the turbo and engine breathe the more air is forced into the engine to make more power. power requires fuel, not a set boost level. more mods mean more fuel needed.

I guess I worded it wrong. My question should've been, with the setup I have, will my stock injectors support 12psi?

maybe but they are going to be wide open. not a good idea.

Ok, I'm fine with waiting and doing it right, was just curious.