Boost Controller and BOV question
Thread Starter
Senior Member
Joined: Jul 2001
Posts: 749
Likes: 0
Boost Controller and BOV question
These should probably be in separate posts, but I hate having a bunch going at once smile.gif
First: Do I need a boost controller with an external wastegate? I was planning on one for the cheap "internal" wastegate on the T-25, but now that I have Onpol's Turbonetics Deltagate II, I'm wondering if I still need the controller. I was only thinking a manual one for now, but I could just wait and upgrade to a nice electronic one later.
Second: Where should the BOV go in the intake piping? Right after the compressor? After the intercooler? Near the TB? For Piping reasons, right after the intercooler will be ideal. It would be next to the "low pressure" piping and could be routed back with a minimum of plumbing.
Thanks,
ac
First: Do I need a boost controller with an external wastegate? I was planning on one for the cheap "internal" wastegate on the T-25, but now that I have Onpol's Turbonetics Deltagate II, I'm wondering if I still need the controller. I was only thinking a manual one for now, but I could just wait and upgrade to a nice electronic one later.
Second: Where should the BOV go in the intake piping? Right after the compressor? After the intercooler? Near the TB? For Piping reasons, right after the intercooler will be ideal. It would be next to the "low pressure" piping and could be routed back with a minimum of plumbing.
Thanks,
ac
Super Moderator
Joined: May 2001
Posts: 11,851
Likes: 2
From: Rancho Palos Verdes, CA
Vehicle: 2008 Toyota Prius 2006 Suzuki SV650S
The BOV should be somewhere between the the TB and the intercooler. The closer to the TB the better, as it catches the pressure spike sooner.
Thread Starter
Senior Member
Joined: Jul 2001
Posts: 749
Likes: 0
Thanks. I just bought an intake pipe from a 1st gen DSM. It has the flange for their bypass valve, and a 45 degree bend. 2" pipe, which is what I'm using. Not bad for $20, saves me welding and I needed that bend anyway.
I was planning on using it around the intercooler, but I also need a pipe to come down from the TB to the intercooler, so I'm sure this will work.
as always, thanks.
ac
I was planning on using it around the intercooler, but I also need a pipe to come down from the TB to the intercooler, so I'm sure this will work.
as always, thanks.
ac
Senior Member
Joined: May 2001
Posts: 1,436
Likes: 0
Random took care of you on the BOV, so I'll answer the wastegate question smile.gif
Wastegates (no matter internal or external) always come pre-sprung to a specific pressure level. The Tial 40mm external that I'm buying comes with a 0.8bar (11.7psi) spring already in it. The thing is, this is the MINIMUM that you could run, with or without a boost controller. A boost controller would only allow you to increase it...
If you're unsure why, remember how a wastegate works: positive manifold pressure is vented through to the wastegate actuator. This actuator is "sprung" so that your manifold pressure has to PUSH against this spring to start opening it. After a certain boost level, that spring will push back and the actuator flapper thingy will open the wastegate and allow the exhaust to route around the exhaust housing.
A boost controller bypasses or limits the amount of pressure that's sent to the actuator, thus it in-turn keeps the wastegate closed and forces the turbo to create more pressure. But it cannot go in reverse... The controller only limits the boost seen by the actuator, it can't "create" boost in order to make it open earlier.
You probably already knew all of that, but for anyone else reading, hopefully it made sense.
-Red-
Wastegates (no matter internal or external) always come pre-sprung to a specific pressure level. The Tial 40mm external that I'm buying comes with a 0.8bar (11.7psi) spring already in it. The thing is, this is the MINIMUM that you could run, with or without a boost controller. A boost controller would only allow you to increase it...
If you're unsure why, remember how a wastegate works: positive manifold pressure is vented through to the wastegate actuator. This actuator is "sprung" so that your manifold pressure has to PUSH against this spring to start opening it. After a certain boost level, that spring will push back and the actuator flapper thingy will open the wastegate and allow the exhaust to route around the exhaust housing.
A boost controller bypasses or limits the amount of pressure that's sent to the actuator, thus it in-turn keeps the wastegate closed and forces the turbo to create more pressure. But it cannot go in reverse... The controller only limits the boost seen by the actuator, it can't "create" boost in order to make it open earlier.
You probably already knew all of that, but for anyone else reading, hopefully it made sense.
-Red-
Thread Starter
Senior Member
Joined: Jul 2001
Posts: 749
Likes: 0
yeah, I knew that about the boost controller, but it also mentions something about how it keeps the wastegate closed until the boost pressure is reached and then "shows" it the pressure all at once. So it won't crack early, I guess.
Onpols Deltagate II is user-adjustable from 6 to 10 psi, and I'm tapping the signal right off the compressor, so 6 psi in the manifold will be around 8 psi out of the compressor (or slightly less).
Hey Red, since you're checking in here: should an external wastegate dump come in before or after the O2 sensor? I ask becasue my turbine outlet elbow has an O2 hole, but I'm also making a downpipe, so I can put the 02 sensor farther down if necessary. It seems like the readings would be the same, since it isn't dependent on volume, and I need the O2 sensor to be reading as hot as possible. Anyway, it's a subject that the books conflict on: "put the 02 as close to the turbine as possible" and "route the wastegate dump tube at least 18 inches from the turbine outlet"
later,
ac
Onpols Deltagate II is user-adjustable from 6 to 10 psi, and I'm tapping the signal right off the compressor, so 6 psi in the manifold will be around 8 psi out of the compressor (or slightly less).
Hey Red, since you're checking in here: should an external wastegate dump come in before or after the O2 sensor? I ask becasue my turbine outlet elbow has an O2 hole, but I'm also making a downpipe, so I can put the 02 sensor farther down if necessary. It seems like the readings would be the same, since it isn't dependent on volume, and I need the O2 sensor to be reading as hot as possible. Anyway, it's a subject that the books conflict on: "put the 02 as close to the turbine as possible" and "route the wastegate dump tube at least 18 inches from the turbine outlet"
later,
ac
Senior Member
Joined: May 2001
Posts: 1,436
Likes: 0
You don't need the dump tube to flow "past" the o2 sensor. You already nailed it -- volume doesn't matter. Throw the O2 sensor where it's most easily attachable and doesn't get TOO hot. You heat the stocker up far enough and it basically goes dead smile.gif
I've gone through a few of these damned things, grr... I'm wanting to find a good wideband alternative, as the "real thing" goes for about $1000+ but there are ways of using a Honda 5-wire O2 sensor found in some of their ULEV cars to work as an alright wideband. Costs about $330 to build a kit as I understand it...
I've gone through a few of these damned things, grr... I'm wanting to find a good wideband alternative, as the "real thing" goes for about $1000+ but there are ways of using a Honda 5-wire O2 sensor found in some of their ULEV cars to work as an alright wideband. Costs about $330 to build a kit as I understand it...
