AVO turbo kit for BRZ - initial build thread

[504]

Hey guys, first time poster here
is exhaust scavenging effect still existent in the AVO UEL manifold? As far as I know the stock headers on this car come in a 4-2-1 orientation which actually creates a vacuum in the next pistons manifold tube to suck out exhaust gases. If scavenging wasn't occurring was it acknowledged during development and does it affect engine longetivity due to possible build up of carbon in combustion chamber?
Also some people say UEL headers are bad for the engine due to varying back pressure experienced by each piston. I know some Subarus come from stock with it, I just want to know what this community has to say about it

Thanks!
(sorry if this has already been discussed)

[Mr.Jay]

The syms car wasn't na was it? Only part from they I have seen was a cf intake

[vinnie86gt]

Just wondering if we're able to use different turbos with this kit? what turbos suit the AVO manifold?? Was thinking of going a gtx3076, gtx3071r or even a gtx2876r... Have seen some good results with this turbo on our cars...
But I do like the stealth of this kit which is why I wanna mix n match

[dabocx]

Is there any benefit to a 3inch exhaust over a 2.5 inch since the avo pipe that goes from the turbo to over pipe is 2.5?

[Sportsguy83]

Originally Posted by dabocx

Is there any benefit to a 3inch exhaust over a 2.5 inch since the avo pipe that goes from the turbo to over pipe is 2.5?

At higher boost levels yes, there is an advantage.

[killerkid08]

Originally Posted by 504

Hey guys, first time poster here
is exhaust scavenging effect still existent in the AVO UEL manifold? As far as I know the stock headers on this car come in a 4-2-1 orientation which actually creates a vacuum in the next pistons manifold tube to suck out exhaust gases. If scavenging wasn't occurring was it acknowledged during development and does it affect engine longetivity due to possible build up of carbon in combustion chamber?
Also some people say UEL headers are bad for the engine due to varying back pressure experienced by each piston. I know some Subarus come from stock with it, I just want to know what this community has to say about it

Thanks!
(sorry if this has already been discussed)

I second this.

[AVOturboworld]

Sorry I'm not replying much lately, I will from next week. Drove down to Formula Drift at Long Beach, CA, added another 1400+ miles on the turbocharged FR-S. Been at the event today, will be there again tomorrow. Hope to meet up with some forum members at the Eibach meet on Sunday as well.

[Cessblood]

Originally Posted by 504

Hey guys, first time poster here
is exhaust scavenging effect still existent in the AVO UEL manifold? As far as I know the stock headers on this car come in a 4-2-1 orientation which actually creates a vacuum in the next pistons manifold tube to suck out exhaust gases. If scavenging wasn't occurring was it acknowledged during development and does it affect engine longetivity due to possible build up of carbon in combustion chamber?
Also some people say UEL headers are bad for the engine due to varying back pressure experienced by each piston. I know some Subarus come from stock with it, I just want to know what this community has to say about it

Thanks!
(sorry if this has already been discussed)

Good question.

[AVOturboworld]

Just got back from Formula Drift in Long Beach, CA last night. Put another 2400+ miles on the turbo kit, I'm at 13828 miles now total on the car - about 9828 miles on the turbo kit. I'll write up my experience with 91 octane at higher boost levels later. It was interesting.

[AVOturboworld]

Apologize for not posting last night, but it looks like the turbocharged FR-S is much better at taking a 7 day road trip than I am.

As you all know, we spent another 2400+ miles driving to California and back for Formula Drift at Long Beach. I took this time to test the AVO Turbokit on 91 octane gas while driving from one end of California to the other. Now, this wasn’t the first time we had tested the car on 91, but those initial tests were done on our 5psi base kit with stock exhaust. This time we wanted to test our Stage 2 setup, on the base 7psi and also at higher psi levels.

To clarify some details, this was with about 500-600lbs of event gear in the car, so it was under a bit more load than normal for most. I also got gas from a bunch of random gas stations without using any octane boosters or any other additives.

Overall, it didn’t do too bad. I started at 8.5psi, and had to bring the car down to 7.5psi when I hit a gas station that had bad gas. And that’s going to be a fact of life for people living in the 91 octane desert, there’s good and there’s bad gas stations down there, and it’s going to make all the difference in the world.

The first log shows what the car was doing on a blend of 91 octane and 92 octane, at 8.5psi. As you can see, it was perfectly happy even with that blend of about 7 gallons of 92 and the rest 91. No issues, no fuss, smooth power delivery.



The second log, well – that’s the good log of pure 91 octane, at 7 psi. Cruising on the freeway, plenty of air over the intercooler, in 80 degree temperatures. There was one knock event. The interesting parts is that the Ignition Advance Multiplier is all over the place even when it’s not knocking. This is the ECU doing a fine job of keeping it from knocking – every time it anticipates it’s going to knock, it was pulling the IAM back to keep it from knocking. Every time it thinks things are going ok, it’s putting the timing back in.




On bad gas, it was worse, with the timing being pulled back even further. That is what it’s supposed to do, so everything was safe. It does show that there will be limits to the boost/power levels you can run on 91 octane, and other factors, such as ambient temperatures, stop and go traffic, etc., will have their effect on performance. Keep in mind that it’s even doing that in n/a form, so the real moral of this story is that 91 octane is evil.

[King Tut]

How do you determine that these are real knock events and not phantom knock?

[AVOturboworld]

I'm running a second knock detector (knocklink) to give a second opinion. The phantom knock at the 2600-3200 range is rather consistent, and doesn't set it off much. When we were doing the initial road tuning, we were also running a pair of knock ears, which is the ultimate determiner. So it would probably have seemed a bit crazy, but we literally had three knock sensors going on the initial tune, and I'm still running around with two (stock and knocklink) at all times.

[King Tut]

Very nice. I have considered adding a second opinion on my car.

[buditjoenawan]

Originally Posted by King Tut

How do you determine that these are real knock events and not phantom knock?

It doesn't matter if it's phantom knock or real knock, since the ECU is applying self preservation tactics anyway. As a result, the car will feel like it's stuttering, hesitating, bucking. Regardless of real or not, the ECU "hears" more things happening and takes preemptive measures to mitigate the possibility. The lower octane fuel, and who knows if there are any weird blends or oxygenation that is in the gas, will inherently be less stable at higher chamber pressures. At this point, I am assuming that the motor is octane limited; smart tuners please refute me.

Paul, does the ignition advance multiplier go beyond 1.0? If I was tuned for 91 octane, then moved to an area with 93 octane, will the ECU adapt to the higher octane?

budi