Max safe boost? [Merged 10-6]

[Turbolaser]

Is it safe to do the boost contol solenoid mod on a stock 1G?

 

[Sean Denny]

You should have no fuel issues with the T25, almost like they designed it that way....


What do you mean "plugged bypass"? I hope you aren't quite sure what you are talking about because that is a bad thing if it is what you did.

Also, you don't have headers. You have an exhaust manifold.

Lastly, what do you intend to tune with and what do you expect to gain? That t-25 is giving you all it's got. Other then minor HP gains from leaning out the overly rich stock fuel map and possibly advancing timing, you won't be able to do much more. Do you have future upgrade plans?

As I am aware of. Seems to me that you, one, didn't read my whole post, as I said, "about all the little huffer can do," this was purely a response to the above question for who started this thread. Second, a plugged bypass, on a stock 2g bov has an atmospheric equalization port that puts turbo pressure to the top of the bypass assisting the spring to open and bypass, thus eliminating "overboost." With this hole plugged, you can indeed boost higher than the 11-13 pounds set from the factory with an mbc, while the bypass valve still works as it should.
I'm planning on DSMLink in time and will be tuning with that, but until then I will choose to play it safe.
As for headers versus manifolds, okay. Call it a manifold. That's fine too, I may not be the sharpest tool in the shed, but trying to prove that someone is an idiot on here is pretty sad, and if this is how it's going to be, I'll find resources elsewhere.

 

[FlyinTalon]

I call it a header too! Turbo header hows that sound. Lol

 

[19gsx91]

This thread is hurting my brain as there is one almost identical going on in the update feed as well. I have not once seen any mention that because he is running an AT 1g the stock injectors are 390 and NOT 450s, I would not recommend upgrading to any kind of injector without a way to compensate for it due to MOST of us not being aware of how 1g AT cars will react to mods just being thrown at them without any sort of tuning/logging, @Dsmkauai I mean you no disrespect but the 1g MT cars and 1g AT cars are different beasts and will react differently as a result..

If I missed the complete manual swap (injectors as well) somewhere I apologize but talk of a 13g points to an AT turbo ecu that expects 390cc injectors. Be a good idea to find out what's in there now and move forward from there.

and headers are for v6s, v8s and 420a guys. we have manifolds

 

[boostdawd]

Potato potatoe. We know what u mean. All vendors use the terminology as manifold. Welcome to the site!

 

[Sean Denny]

Potato potatoe. We know what u mean. All vendors use the terminology as manifold. Welcome to the site!

Thank you!

 

[Dstarperformance01]

Technically the term header refers to aftermarket terminology and exhaust manifold is a factory term. Manifolds can be cast or tube style. The number of cylinders dictates nothing as well if it's for a turbo application or not.

Potato potatoe. We know what u mean. All vendors use the terminology as manifold. Welcome to the site!

 

[Sean Denny]

I would agree.

 

[Dstarperformance01]

Oh yeah, WELCOME to the site

 

[Sean Denny]

Oh yeah, WELCOME to the site

I thank you!

 

[doubleclutch]

As I am aware of. Seems to me that you, one, didn't read my whole post, as I said, "about all the little huffer can do," this was purely a response to the above question for who started this thread. Second, a plugged bypass, on a stock 2g bov has an atmospheric equalization port that puts turbo pressure to the top of the bypass assisting the spring to open and bypass, thus eliminating "overboost." With this hole plugged, you can indeed boost higher than the 11-13 pounds set from the factory with an mbc, while the bypass valve still works as it should.
I'm planning on DSMLink in time and will be tuning with that, but until then I will choose to play it safe.
As for headers versus manifolds, okay. Call it a manifold. That's fine too, I may not be the sharpest tool in the shed, but trying to prove that someone is an idiot on here is pretty sad, and if this is how it's going to be, I'll find resources elsewhere.

I wasn't trying to be mean. Just trying to keep you from getting actually flamed later on. My point was that there isn't a great return on buying link unless you are planning to upgrade the turbo and injectors. This is why i was curious about what your plans were.

As far as plugging the BOV, I may be wrong, but plugging your port would mean that the boost pressure is not helping keep the BOV closed and you are solely relying on spring pressure. In addition, when you shift and the BOV would see vacuum from the manifold and cause the BOV to open, it isn't which means you are not relieving the pressure in the system as effectively or at all.

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Any thoughts?

As far as a manifold vs. header is concerned. No one has been proven an idiot by getting a name wrong. The people who are regarded as morons on here are those who commonly spew misinformation, get butt-hurt about everything, and refuse to listen to sage advice. Feel free to go elsewhere if those terms aren't fair, but you won't find a better knowledge, experience, or better people on any other DSM site.

 

[Sean Denny]

I see what you mean by your diagram. The stock 2 g recirc valve had the outer hose and nipple as shown in your diagram, however deep inside the valve, there is another hole, a pilot hole basically, that actually lets boost pressure air up above in the same chamber as the spring and actually pressurizes the chamber while under boost. So what it does is assist the spring and shoves the bypass valve open.... under boost! This is why us dsm'ers hate the 2 g recirc valve. Because with that little hole being open, the valve will only allow about 10-12 pounds of boost to the manifold before it starts leaking/bleeding off. By blocking this hole, the recirc valve relies strictly on spring pressure/manifold vacuum to relief and as boost builds, basically seals the valve off tighter, however when you let off the throttle, air fills the spring chamber assisting the spring and.... pssshhhh.... it triggers and doesn't deadhead the turbo. Plus I'm able to run the boost up a bit, not unnecessarily build unused boost and heat, and have a marginally more efficient t25 (for whatever that's worth! Lol)
For your other questions sir, I'm probably not going to go crazy but I would like to do a t28 and probably some 550 or 650cc injectors, thus why I wanted to go with Link. I'm not crazy on attacking a clutch yet and from my understanding, the stockers are only good for about 300 horse before they start slipping. But I figure baby steps.
I apologize for jumping off the hook.

 

[doubleclutch]

Ah, cool. I didn't know that about the 2g recirc. I went immediately to a 1g on my car.

You could consider the 16g family of turbos too. The T28 may leave you wanting and the 16g should have to power you need to grow with your mods. I currently am at roughly 300 hp and have not seen slip yet on my stock clutch. *crosses fingers*

Welcome to the site and good luck!

 

[Sean Denny]

I've actually considered that but 2 concerns I have were, 1, can the boost be dialed back enough to where the stock 450's can be used until I get the bigger injectors and Link, and 2, what is installation like on them? Do the oil and coolant lines line up and I've also been seeing that you have to get a j pipe for the stock plumbing. No biggie on either, i just don't know what id be getting in to.
That's good to know that you're holding 300 with your clutch. I'm not afraid of a beefier clutch itself, but I am scared to death of that dressed crank walk that a stiffer clutch could impose.

 

[doubleclutch]

There are many guides of how to install a 16G. I actually posted a parts list here. The coolant lines can swapped (front to back and back to front) and slightly bent. The oil feed needs to be run from the head (30$), and the oil return can have the bolt holes ground out to work. J-pipes are everywhere on the classifieds.

As far as injectors are concerned, yes and no. If it isn't properly ported and you have a free flowing exhaust, your 16g can creep up to were you run out of injector. When i installed mine, i was on 450s and was able to keep wastegate pressure (9-10 psi) to redline. That is definitely fine for the injectors. You can take a look at a ballpark calculator to figure out how much boost you can run on your 450s here. From taking a look at it, you start to get into trouble after about 13 lbs. Anything over 15 could start causing issues if you are running the stock-ish 10.5:1 AFR

I wouldn't be worried about a modest clutch. It seems like some people on here are cursed with crankwalk after crankwalk and the rest have no issues. *knocks on wood*

 

[Sean Denny]

This is some great info and a great table! I really appreciate you copying me on this stuff. Thanks a ton!

 

[Alan 98 gst]

Yea just do a full tune up first making sure your car is in the best shape it can. I believe the max you can go is 16 psi. I would recommend installing an aftermarket boost gauge as well.

 

[Sean Denny]

Check. Got one of those now, but definitely appreciate the advise.
One question I do have for you dsmer's though, is when talking duty cycle, does that cycle remain constant throughout the RPM if you're running a steady, say, 15 pounds of boost all the way to redline? It seems to me like the duty cycle would actually increase with higher RPM at a fixed boost level. Or are the numbers based off of that fixed boost rating at 7000 RPM?

 

[doubleclutch]

Duty cycle changes based on airflow. The table I gave you is at the RPM you entered. The most conservative would be to estimate duty cycle at redline (7000) RPM. Unless your turbo can't keep that boost up till redline and then it gets slightly more complicated.

Or are the numbers based off of that fixed boost rating at 7000 RPM?

I guess what I am trying to say is . YES

 

[Sean Denny]

Actually, that makes perfect sense now. Correct me if I'm wrong but here it goes. So say it takes 1 millisecond to complete a full duty at 3500 rpm. Based off of airflow, it's still 85% duty cycle at full throttle. However, the same event at 7000 rpm will occur at .5 milliseconds, injector is still at 85% duty cycle, everything is just happening at a faster rate, providing, as you said, the boost remains constant across the RPM's, which, as we know, the t25 kind of falls on its face past about 4500rpm.
Did I get that right?

 

[Vegas Smith]

http://injector-rehab.com/shop/idc.html

It sounds like injector pulse would be the changing variable based on airflow? Sorry, I haven't read the whole thread and am learning myself.

 

[doubleclutch]

Duty cycle is the percentage of time the injector is open during an intake cycle. Each intake of the engine will suck in the same amount of air roughly (obviously more if boost is going up) but you injectors can only flow fuel at a certain rate. The duty cycle goes up because the injector must open sooner and close later during a cycle to ensure enough fuel is injected. Once you reach a certain amount of fuel needed you simply cannot flow enough with small injectors to keep your a/f ratios in the right spot.

Actually, that makes perfect sense now. Correct me if I'm wrong but here it goes. So say it takes 1 millisecond to complete a full duty at 3500 rpm. Based off of airflow, it's still 85% duty cycle at full throttle. However, the same event at 7000 rpm will occur at .5 milliseconds, injector is still at 85% duty cycle, everything is just happening at a faster rate, providing, as you said, the boost remains constant across the RPM's, which, as we know, the t25 kind of falls on its face past about 4500rpm.
Did I get that right?

your almost there. At 3500 RPM the engine is taking in the same air per stroke, but has less more time to inject fuel then at 7000 RPM so the duty cycle will be lower at 3500. Think of it as (time injector spent open/time per intake cycle).

http://injector-rehab.com/shop/idc.html

It sounds like injector pulse would be the changing variable based on airflow? Sorry, I haven't read the whole thread and am learning myself.

Sort of, airflow changes because you are getting more cycles during the same time frame as rpm increases. The faster cycles means you need higher flow to keep the same amount of fuel going into the air charge in a shorter amount of time.

Think of it like a mold on an assembly line. Everytime a mold shows up it gets injected with ..let's say chocolate. If you double the rate the molds show up, you have to double the flow of the chocolate to make sure they are being filled.

 

[Dusty96]

I have a few questions regarding boost. For I've never built a boosted car. I'm wondering how much boost a completely stock 4G63 can take.

And a very slightly modified DSM can take. It's gotta few things done, 950cc injectors. an hx35 turbo, external waste gate, and o2 dump. And a boost controler.. That's it's. I gotta basically redo everything because it barely runs. And I don't wanna break something with too much boost by mistake so I was thinking turning down boost until I tinker some. bought the car like that to get it back on its feet so too say.

Car is a 95 eclipse GSX.

 

[A Sharp]

What is your tuning setup?

 

[Dusty96]

What is your tuning setup?

A very Shitty e85 tune that barely runs. I plan on putting it back to 93 soon and to a stock fuel map. Other than than an EVO 8 ECU

 

[A Sharp]

Gotcha. If you don't have a way to log knock or a wideband, I wouldn't run more than 14-15 lbs.