Greddy Turbo - Should I Weld on External BOV?
 

FYI and Personal Findings (BLUF):
When I started this thread it was to help learn more about the GReddy turbo kit for the BRZ/FRS/GT86. As some of you know the kit does not come with a BOV flange. It was designed to not need a BOV but can be added.

Key Notes:
Q1: Can I add a BOV to the GReddy Turbo Kit?
A1: Yes; however, if you add the BOV make sure to tune the car with it on. It will affect the tune if you decided to put it on later.

Q2: Is a BOV nessessary for this kit?
A2: No; GReddy designed this turbo kit to not require a BOV. If you look at some professional racers like Ken Gushi they do not use a BOV on this kit. If you are pushing a high amount of boost then you will need to consider a BOV but not on this kit.

Q3: Where do I mount the BOV on this kit?
A3: Hotside of the intercooler right after the turbo. This is where FullBlown Motorsports and GReddy recommended the BOV to be installed. The BOV should have just enough room to clear the front lip of the car and before the charge pipe bends downwards to connect to the intercooler.

Q4: Will I not have the cool BOV noise if I don't have a BOV?
A4: Yes/No; you won't have the sharp blowoff sound that a BOV will give. However, this kit gives its own sound from the compressor surge. It is a fludder sound and actually sounds pretty sick. For those that know about turbos they will be impressed by hearing that type of sound. This is a quality turbo kit.

Q5: What is the max PSI I can push on this kit without modifications?
A5: 14 PSI. When talking with GReddy USA and testing this kit on the dyno the max PSI with the current wastegate will level out at 14 PSI. FullBlown Motorsports (@FullBlown) tested the theory of pushing 17 PSI on this kit. However, the boost didn't remain stable and would drop down to 14 PSI. On a side note, GReddy USA did say this kit can handle more PSI if the wastegate was upgraded. There is still room for play.

Q6: Can I use the stock 2.5 BAR Map Sensor on this kit?
A6: Yes, Fullblown Motorsports (@FullBlown) was able to test this kit on E85 with 1000cc ID's and a Deatschwerks DC-65c fuel pump pushing 14PSI on the stock map sensor. The end result on the tune was 300whp.

Q7: Does the GReddy Turbo Kit spool (build boost) quick?
A7: Absolutely, don't let size discourage you from getting this kit. This turbo has a mean bite to it and has room for more potential (based off of what GReddy USA said over the phone). I believe this kit is very friendly for every day drivers to track/drifters. If you are just looking to max out your car with boost and power than go with a bigger turbo/different company.

Q8: Can I do a nice burnout with just pushing the throttle?
A8: Hell Yes! When rolling out of a stop in first and/or second this turbo spools quick enough to allow for fun drifting around cornors with just pushing the throttle (this is experienced from my tune from FullBlown and using E85).

Q9:
A9:

Sources: FullBlown Motorsports
GReddy USA
Trial and Error
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Original Post Below:

Hey Guys,

Just got my Greddy Turbo Kit installed last week and I am having FullBlown tune her this week. However, since the Greddy Turbo Kit has an internal waste gate that dumps to the exhaust I am contemplating on puting an external BOV in. I have the flange and a Greddy FV BOV that I can install. I've contacted Greddy about installing it and should be no problem on the hot side of the turbo.

Basically, my question is should I just keep the stock Greddy setup with the fludder noise or should I add the sick sounding BOV? Actually, they both sound pretty cool. And will adding an external BOV degrade the turbo's performance design?

Thanks all! :)

EDIT: Meant hot side of intercoloer; not hot side of turbo. My bad.

You will benefit more from recirculating instead of venting to the atmosphere.

Venting to atmosphere is always better in regards to boost regulation. The excess sound is subjective.

Get a 50/50 BOV and get the best of both worlds :D

Wouldn't recircing the gases result in less lag? I thought that was the whole purpose of recircing? That's the common understaning in the DSM community at least.

The only real reason is to have the benefits of an ewg but the sound of an internal. VTA will outperform every time.

If you must recirc back into the DP, you must do so as a angle to allow a smooth transision into the exhaust. An abrupt 90* entrance will hinder performance.

The only reason to recirculate is if your MAF is before the turbo. That isn't the case on our cars, so feel free to vent to heart's content. I would definitely have LJ put a BOV on the Greddy kit for you.

Are we talking about A BOV or a wastegate? I'm confused lol. The only reason to recirculate a bov is if you have a draw-through maf and can't meter the expelled air.

Yeah, I was thinking of having LJ weld the flange on for me.


@Everyone, Thanks for all your inputs. There are a lot of forums out there that go back and forth but they don't know our cars like you guys do. Thanks again!

I added a BOV to my greddy turbo kit. A greddy rep said it doesn't really need a BOV but I think it's a must have.

Unless Ive been mistaken all these years, a bov goes on the cold (compressor) side of a turbo, not the hot (exhaust) side. Unless you are meaning adding a bov wouldn't affect the hot side.

Regardless, IMO, add the bov.

He didn't mean hot side of the turbo, he meant hot side of the intercooler or the piping from the turbo to the intercooler inlet versus the cool side or the piping from the intercooler outlet to the throttle body.

Right on; I called them and asked about putting one on. Greddy just told me to weld the flange, bolt the bit*h on and rock hard. Haha. Might of exaggerated a little bit tho.

Thanks for clarifying! :thumbsup: