rr_allroad

You know sometimes it the little things. I have been having an issue with my AR.

When the car hits about 5000 rpm and beyond under full boogie the power would taper off and the motor felt like it was having turbulance in the intake or stuttering. Hesitation is a better description. Not that you would feel it in the drivetrain but you could feel it in the motor.

I attributed this to maybe an issue with my brand tortilla snacks. I thought about this more and consulted some know-it-alls and they said I was full of it, the snacks were fine.

Then I thought maybe there was some torque related issue with the tip tranny but that didn't make much sense.

Then I thought maybe it's the plumbing. So I looked for damage or missing hoses. No Dice. Then I thought maybe I should install some bitchin BPV from Forge or someone just to make me feel better, like I was making a difference in this issue. Then a wise Audi guy at a local tuner suggested that if I really want to change to put in 710N in place of my 710a/b to enhance reliability etc... No mention of my problem being fixed by this.

Well as you can guess by now I put in 710n's and I have a new car. My AR runs like a raped ape. Totally cured of it's high rpm hesitation and I know you are thinking this normally sane allroader has lost his brain but the car shifts better! I wouldn't kid a kid. It really does.

Bottom line - I expected nothing and got everything. Best $63 I ever spent.

Lightweight-USPowah

What mods do you have?

Northern Ivy

Raped Ape, uh ohhh...the ASPCA is going to be paying you a visit!

myroad

however, that hasn't stopped others, so could someone explain how this 710N (is it a valve/wastegate?) helps performance,or anything? Thanks.

RostyVyg

How hard is it to replace the BPVs' by yourself?
Does it take much time or any special tools?

Thanks.

Arnzo

The stock valves tend to fail over time, especially if you rev hard / chip. Putting in new valves (provided you are experiencing issues) can provided better throttle response and more linear power delivery. I replaced my stock valves with Bailey valves. They are a much better quality valve than the original valve. Also better in build than the 710N but the 710N probably offers the exact same benefit and offers the benefit of being more stealth. If a tech looks at my engine he'll immediatley see that I have changed my valves (Baileys are bigger than stock, are shaped differently and are a slightly different color). The 710Ns, however, look the same as the 710 a/b. The other big benefit of the 710N over an oaftermarket valve is cost. $65 vs $250 - $300.

Clues

When you let off the gas, your throttle plate closes. However, your turbo is still sending air towards your engine. The pressure "bounces" off of your closed throttle plate and back towards the turbine blades in the turbos. With nothing there to stop it, the result is the turbine blades slowing down. This might not be good for the longevity of the turbo, but the main concern is that when you shift and get back on the gas, you have turbo lag as the turbine blades come back up to speed. You deal with this by installing one of two things in the space between the turbo and the throttle - a blow-off valve or a bypass valve. A blow-off valve is nothing more than a valve that is forced open when the pressure buildup reaches a certain level and allows excess air to vent into the atmosphere. A bypass valve works the same way except the air is directed back into the engine air intake system, but before the turbo (so it can be re-used). Both types of valves work well to prevent large pressure drops and wear on the turbo. The advantage of a blow-off valve is that it is louder and sounds much cooler, while the advantage of a bypass valve is that it allows air to be reused, resulting in a quicker spool-up when you get back on the gas.

The 710N was designed for the TT to withstand higher boost levels than the stock 710As (used in all other Audi Turbo applications). When functioning properly, there is little or no difference between the 710A and the 710N. However, the 710A valves have been prone to damage - specifically, the rubber diaphragm inside the valve has been known to tear under the pressure of higher boost levels. The 710N used a more durable (silicone based?) material that resists damage.

rr_allroad

Just to be clear my AR had this hesitation since new (14,000 mi now). It wasn't as apparent until I started snacking at about 7,000, but still it was there.

The 710N is physically the same warranty friendly appearance as the 710B's I removed. The difference I can see and feel with the valves is the diaphragm of the 'B' is easily deflected with my finger and the 'n' is much stiffer.

The install is super easy: Flat screwdriver, 7mm nut driver, pliers. Remove the front cover on the engine (labeled Bi-Turbo), twist the two screw heads a 1/4 turn to release, gently lift up on the rear of the cover. The two BPV's are right there. MAKE SURE when you do this you purchase the crimp clips for the tiny hoses. They are different sizes left and right. The rest is self-explanatory... took me 20 minutes start to finish.

My raped ape runs a K&N panel and ApPReciates tortilla snacks, heavy on the salt.

I know most people buy new doodads for their car and think it does something when it doesn't really. "Hey this RS badge is good for 5 horsepower". But this little change has really made a difference I'm totally surprised.

ar2002

That's the conclusion I'm drawing from the discussion thus far. What do YOU say?

rr_allroad

Even though my car had an issue that wasn't the actual motivation to swap my valves. I had done a ton of research and concluded that the 710a/b would fail and the 710N would provide some extra margin of reliability.

The fact that it fixed the hesitation issue is a big bonus. Moreover my AR experienced the hesitation even in stock trim.

Your valves may be fine at this point so swapping to the 'N' may not yeild any perceived difference. It may be peice of mind for $60.