View Full Version : Final st215 questions/confirmations

12-03-2014, 05:38 PM
So, trying to button up some things on my alltrac/4th gen 3sgte swap and just want some confirmations or corrections from people here.


1 - Opening on IC leading to TB. I assume I just route a tube to the intake I setup, correct?

2b - This is connected to 2a which is connected to the manifold. Judging by the diagram Tim showed me it looks like that should go to a vacuum valve of some sort that I do not have. Can I just cap this like I have it/run a boost gauge off it?

3 - Seems to be connected to the idle control valve, from what I can tell. If I plug it, the motor dies. Can I just throw a mini filter on it and call it a day or should it also be ran to the intake?

12-03-2014, 05:49 PM
I have some pictures from Jasmine somewhere of that area. Let me dig them out.

12-03-2014, 07:04 PM
You could put a mini filter on the IAC line, although Id run it to the intake. It makes less noise if you route it to the intake. Never been a fan of that loud ass whoosh from idle on cars just running a mini filter.

12-03-2014, 08:07 PM
K, I will take your advice and connect 3 up to the intake. It is a bit obnoxious right now, could only imagine after I get to driving her all the time.

And thank you Tim, whenever you find your pics.

12-18-2014, 08:30 PM
I found this pic and have a question:


It looks like there a BOV located right before the TB. Is this a needed thing or can I just recycle it into the intake?

Sorry if its a noob Q, but just trying to iron out details before making my intake.

12-18-2014, 08:57 PM
I know I have these pictures...

The BOV is optional to be honest. It's not necessary. Some folks put it before the TMIC, others after. In my case I had it about 24" before the throttle body. The stock ST215 had a bypass valve went from the intercooler to the intake assembly. I've circled it in this picture.

I'm going through the 1500 pictures I have from my build looking for those shots.

12-18-2014, 09:24 PM
So the stock has a bypass valve. Now, with it being optional, would it be safe to just cap off the inlet, or should I buy a bypass valve from a saab/volvo/etc and install it? I am just looking to recirculate it if I need something there. No PSSSSS noises for me.

12-18-2014, 10:37 PM
Going back to your first post:

This is where you would stick a BOV if you had one. Stock this would have a house that runs over to the airbox and connects to a bypass valve which is mounted to the intake box. If you're not going to run it you can just cap it off. You'll have a bit of turbo flutter but it shouldn't hurt the turbo.

This is the other line that connects to the other port on the stock BPV to actuate it and allow it to vent. You can connect your boost gauge here.

That's what I did. I just put a small filter on it and called it a day.

The black hose you have pictured that is between #1 and #3 I'd stick a oil catch can in there. Great quick visual to see how the motor is running and if you are having excessive oil blow-by.

I finally found teh damn thread...


That's how I connected my boost gauge and everything else. I have a crapload more pictures if you'd need them.

12-18-2014, 10:45 PM
#1 - That port is either capped (not routed to intake) or valved, If you don't have a valve there then you don't build boost. If you aren't going to run a blowoff/bypass, you have to cap it, but that's not really recommended. Without a valve, the pressure wave from snapping the throttle shut propagates back off the throttle body and slams into your turbo, and that wave will bounce back and forth in the intake until that wave dies. This action is VERY hard on turbos, especially the more boost you build.

If you don't want a blowoff valve noise, run a the output of the valve back to the intake. The quiet one that a lot of people use is the one from a Volvo 740/850. However, there are some aftermarket blow off's that are designed to be routed back to the intake and aren't particularly loud.

2a/2b - If those are just two ends of one vacuum line and not connected to the intake manifold at this time, then you can ignore them. Also realize you will need a vac line off the manifold to go to your BPV, already discussed. you could use this line as the supply for that.

12-18-2014, 11:20 PM
Facime these lines he's asking about are all together. As you mentioned #1 goes to a valve (or capped) and #2 goes to the valve (or capped or to a boost gauge).

I did a lot of research back when my wife told me my car was too goddamn loud. In my research I found that this is an HIGHLY DEBATED topic on mr2oc, alltrac and other forums (skyline, honda, etc). Of course though the Honduuuh boys like them cuz 'it adds like 100 HP'. Here's my .02 on the subject.

ST165: No BPV/BOV from the factory.
ST185: No BPV/BOV from the factory.
ST205: Stock BPV
ST215: Stock BPV
MR2 3sgte: Stock BPV

So what does this mean? No freaking clue. But I know that at the stock boost levels of the st165/st185 a BPV really isn't necessary. I ran my 215 for about 6 months at 12psi with no BOV. She ran like a champ. When I started running 16, 17lbs of boost I put it back on. One thing to point out though, I had a FMIC connected. I had a lot more area to dissipate the pressure wave. I also didn't shift aggressively at high boost. When I was shifting I typically had 5-8lbs of boost built.

Anyway, YRMV.

12-19-2014, 04:46 AM
At 6-8psi in the stock system, no BPV/BOV is fine, but who runs stock boost anymore? Especially in a motor we all know can do significantly more with no mods.

The problem with running no bypass is two things: 1) the pressure wave slows the turbo down slightly, so you lose some performance as the turbo has to spin back up (Also, energy dissipated = more heat). and 2) it puts more stress on the seals and bearing surfaces of the turbo. You might not see this for a while but eventually this is going to wear the turbo out quicker.

Also, just because Toyota might not have done something in their stock configuration does not mean its the best way to run something. Sometimes, there is room for improvement. For example, no one runs stock headbolt torque on a 7M.

Last thought, I cant think of a good reason NOT to run a BPV. The Volvo one is dead quiet and you wouldn't even know its there, and I personally cant stand the sound of turbo flutter.

12-19-2014, 04:31 PM
Thanks for the input. Think I will be ordering a bypass valve soon and try and button this all up.

12-19-2014, 07:28 PM
bov is not exactly needed. I ended up putting a tial in mine due to the compressor surge driving me nuts. All the other stuff you have is IAC related. Make sure you give it a good cleaning with carb choke before you get that thing going.

12-20-2014, 06:43 AM
I dont run a valve. Brian dont either. And many MR2 bros dont. I personally think they dont decrease turbo life, and they just slow you down.

Dont get a valve just cause one guy on here says to. Dont run without one just cause one bro on here says not to.

Make your own decision. Theres tons of discussion and arguments on both sides. I've spent my hours, and days on the internet researching it so I feel I'm at least educated on my decision. Will it be a bad one? Dunno. I'll let you guys know if my turbo frags out anytime soon, but if it lasts 20k miles then dies, there can be no correlation made because it is used. But for me, if I run it, get 100k out of it. That's proof enough for me.

12-20-2014, 06:45 AM
Facime, run one, then remove it and run. Your car will be faster and more responsive between shifts. I've noticed it on mine.

12-20-2014, 08:51 AM
Meh, whatever.

12-20-2014, 01:38 PM
True it will be better with out a bov. However, that compressor surge noise arggh so anoiying. Especially with a 4th gen when you tap the gas and it starts to spool

12-20-2014, 07:28 PM
Well, I bought a cheap one for trying. Figure I can get a cap for now and then play around with it later.

12-21-2014, 12:11 AM
My turbo dont surge. But its relatively small. In fact riding in my car you'd never know I dont have a valve. It still blows off. Just not all of it. It only purges the delta. So piping never goes to 0. And the valve dont have to close so spoolup happens quicker too.

12-21-2014, 12:18 AM
Man I wish I could do the 4th Gen swap. It spool pretty quick and faster?

12-21-2014, 12:31 AM
Once it spooled it was wicked. Mine had a lag due to the large FMIC and piping. Once it boosted though it boosted

Sent from my SM-N900V using Tapatalk

12-21-2014, 12:40 AM
Yes it does

12-21-2014, 04:07 AM
good to know. I know I iwll not be getting the swap for a while but I was wanting the st205 but leaning more towards the st215 now.

12-21-2014, 05:31 AM
good to know. I know I iwll not be getting the swap for a while but I was wanting the st205 but leaning more towards the st215 now.

I went with the 215 cause it was cheaper and its stock power is good for my needs. If I ever hit 300 flywheel hp I will be happy.