Free Horsepower For Gtst & Gtr's

[Wardest]

I had my boost restrictor taken out. The only issue is that nothing has actually changed. I'm not running anymore boost that I was before. The car doesn't feel any faster.

I think SIKR33 is a bit upset.

[rev210]

sikr33,

Sorry if it seems a little discouraging. After all you are only trying to help out.

The factory solenoid is nothing but a bottleneck for real performance. You will get better results with a bleeder performance wise and ultimately the very best results with an EBC.

Keep looking for those 'free horsepower' ideas tho', I'm sure you will run into a few that people haven't tried and then the silence is golden.

[Steve]

Good on you SIKR33, for sharing something with everyone else. That is after all what this forum is all about, as is the constructive comments that have been posted - IMHO.

2500 members, you cant expect them all to get along unfortunately.

[Guest 570CK]

Originally posted by SIKR33

YEAH U KNOB BUY A BLEEDER. good one stupid stop giving ridiculous info to people Yeah guys listen to them they know lol

buy a cheap ass bleeder and spike ur turbo. im gettin off this thread as ur all assholes go and blow up ur turbo's u dumb fux

Yo.. its good people have ideas to share. But some people think if its not in there magazine, then its not true. Those knobs come and go.

I thought forums were for ideas, not a group of girls bitchen.

So keep em coming SIKR33. Don't worry, just chop em on the street.

And to the guys who reckon they don't have a restrictor. Maybe thats cause you purchased the car second hand and the owner before took it out.

Anyways, Ideas are great.

[Guest wasted]

don't even consider, such a stupid modification as this. as rev210 said, you will gain NO more boost, i'd bet this guy has damaged his own car, and just wants to see it happen to others. if you want more boost just go and buy a bleed valve ~$100.

[solution]

ok people, he has stopped using caps, dont jump on the bandwagon and bag him, hes just trying to help, its not like you would just hear one opinion and go and do something like this, weigh up the pros and cons

oh and rev210, compared to what is a GTS25-T a slow car?

jeez you must have something fast whats your other car?

[Blitz]

Guys its simple, if you want to have your restrictors removed, just check with your workshop first and get the proper advice, its not that hard.

[DennisRB30]

Threads like this are the reason I am very sceptical when taking advice from net forums. Fortunately, it’s sometimes quite easy to tell when a someone has no clue what their on about.

I thought about the mechanics of it, and came to the conclusion that removing it could only let the wastegate actuator diaphragm receive a higher boost level under variations in boost, due to an unrestricted boost signal from the intake. Since its boost pressure that activates the wastgate, a higher boost reading at the actuator would cause the wastgate to open faster therefore dulling boost response and possibly even reducing boost* (*depending on the function of the factory boost solenoid, which I’m not entirely sure of it’s function). At best, removing it could only reduce boost response whilst still leaving max boost as the factory intended it.

Well, theorising is just that, so I tried it for myself. Not to my surprise taking out the restrictor done absolutely NOTHING to increase boost. I urge any sceptics to try it for themselves. Remember if you do anything else other than remove it (eg dial in cams), your results will mean nothing.

To further the test I replaced the boost solenoid with a bleed valve with the restrictor not in place. The bleed valve did not function properly because there was too much airflow in the hose. This resulted in the bleed valve not being able to bleed off enough air to reduce the boost signal.

I put the restrictor back in which reduced the potential air flow in the wastegate line, therefore allowing the bleed valve to bleed enough air to reduce the boost signal. (the less boost signal the actuator gets the more boost your turbo will make)

The valve I used was a proper industrial bleed valve used for pneumatic systems. (The wastegate actuator system is nothing more than a simple pneumatic system). I have never recommended anyone to waste money on a $100+ “specialised” bleed valve for increasing boost, but I suspect that some of them might have a restriction in them on the intake side therefore negating the need for an extra restrictor.

Anyway, the restriction on the wastegate line plays an important role in INCREASING the boost and adds sensitivity to the boost controler. BTW there is no spiking evident at all. Maybe spikes only occur when there is no restriction in the line to limit the air flow in the wastegate line?

[giz01]

3.18 What's this about a free boost upgrade?

It's true. You can get a 1-2 psi upgrade by removing the boost restrictor on the top of solenoid valve. It is identified by a white band on the hose which goes from inlet pipe to the solenoid valve. This pipe is at the top of the boost control solenoid. If you don't want to cut the hose, just get a piece of 1/4" fuel hose the same length, and replace the original hose with this new piece.

Remember to reconnect all hoses. There is nothing left off or disconnected after this modification. Let me stress this again, There is nothing left off or disconnected after this modification. Take the car for a drive and watch your boost gauge. Make sure there is no major increase or decrease in boost level. If there is, stop and recheck your work!

One or two PSI might not sound much, but remember that the export-spec cars run around 10psi (0.7 bar), this is up to twenty percent, or somewhere about 8-10 kilowatts at the rear wheels. On an S15, we saw 20KW at the wheels. Not bad for nothing!

So, the obvious questions are, why does it work, and will it cause any damage? It works because removing the restrictor changes the pressure signal to the wastegate actuator. From the factory, it is designed to open slowly, and make the transition nice and gentle, by allowing the wastegate to "creep" open a little before we reach the preset boost limit. The restrictor is what causes this creep, by restricting the flow from the solenoid valve. Without it, the wastegate stays shut (or as close as mechanically possible) till the preset level is reached. The opening is now a "snap" operation.

Will it hurt anything? We know of cars which have run this modification for 2-3 years without problems. If you fit an aftermarket boost controller, you generally take the restrictor hoses out anyway. Your mileage and durability may vary.

[DennisRB30]

Giz01 thanks for setting it straight. I was unaware of a restrictor in the solenoid line. A boost increase by removing it makes total sense (as opposed to removing the restrictor marked by red in the wastgate line as indicated by others in this thread).

It would have the same effect as opening a bleed valve to release pressure from the wastegate line.

Just make sure you DON’T remove the restrictor in the wastegate line as well, otherwise it might not work for the same reasons a bleed valve might not work.

[Black33]

Removing the restrictor will do nothing!

[giz01]

Maybe it doesn't on line, BUT it did work on gf's s14!

[giz01]

And thanks to 200sx.org for this info

[Black33]

it doesn't do anything on a gtst

The restrictor is what causes this creep, by restricting the flow from the solenoid valve. Without it, the wastegate stays shut (or as close as mechanically possible) till the preset level is reached. The opening is now a "snap" operation.  

I don't understand how your saying above that the restrictor causes creep????

If it restricts the flow to the wastegate it will do THE OPPOSITE!

Also, you say that removing it will mean the wastegate will stay shut until it reaches the preset level - can you want to explain why this is????

[Doctor]

You still have the same psi of air going to the wastegate regardless of a restricter or not. I beleive all it would effect is controlling the spike factor.

My theory anyway.

[DennisRB30]

Originally posted by Black33

it doesn't do anything on a gtst

 

I don't understand how your saying above that the restrictor causes creep????

If it restricts the flow to the wastegate it will do THE OPPOSITE!

Also, you say that removing it will mean the wastegate will stay shut until it reaches the preset level - can you want to explain why this is????

I have not looked to see where this restrictor is or how it would work with the solenoid. If it’s in the BOOST SOLENOID LINE, it will not be restricting any flow to the wastegate, on the contrary, it will allow the pressure to back up faster in the wastgate line dulling boost response. Removing it might allow more air to be bled away from the wastegate line in the same way as a bleed valve, thus increasing boost.

I have not inspected it or tried removing it but at least the theory makes sense, unlike removing the restrictor marked by red in the wastegate line.

[DennisRB30]

Originally posted by Doctor

You still have the same psi of air going to the wastegate regardless of a restricter or not. I beleive all it would effect is controlling the spike factor.  

My theory anyway.

Scenario 1.

Having restrictors in the WASTEGATE line without any type of wastegate bleed will not change the amount of PSI the wastegate gets. However it will increase the TIME it takes for the PSI to build up in the wastegate line after the restrictor. This effect will reduce creep, and if the volume of air in the lines after the restrictor is too big, it might cause spikes. Eg, if you set the boost to 10psi, the pressure in the line before the restrictor (actual boost pressure) might reach 13psi but the actuator might only see 10psi because the pressure in the line has not had time to equalise yet because of the restrictor. But if the system is designed right no spikes will occur and the system becomes beneficial by keeping the wastegate closed for longer before the set boost is reached

Scenario 2.

When there is some sort of wastegate bleed, eg bleed valve or solenoid the restrictor becomes a bottleneck, which allows the pressure behind it to decrease below that of the nominal boost pressure. The bleed valve allows air to escape, and the pressure is reduced because of this. Without the wastegate line restriction the bleed valve would have to bleed off an overly large volume of air to make a reduction in pressure.

That is why removing the restrictor in the SOLENOID line may* increase boost, because it might then be able to bleed off enough air in the wastegate line to reduce the pressure below that of nominal boost pressure.

The moral is leave the WASTEGATE line restrictor in!

Does this make sense?

[Guest 570CK]

It slows the flow of air.

Dude its simple, don't have to be einstein to work it out.

1. Your car has two things that control your boost. Actuator Spring and your Boost Controller Soleniod.

2. Restrictor. What it does.. It slows down the flow of the air.

Thats all it does. This cause the boost to be more stable. Less chance of boost spikes. By slowing the rate of flow, it doesn't add extra flow of air to the EBC soleniod. Which make the wastegate open gently

3. Why does removing the restrictor do anything? You increase the flow of air. Therefor the Boost Controller Soleniod is counter acts this by opening its valve up a bit more to release the extra flow. This causes the pressure in the line to drop. So the Wastegate will stay close a bit long. Which causes the boost to spike.

4. How does a EBC / bleeder valve work? Same idea. It releases air to increase the boost level. They don't call it a bleeder valve for nothing.

5. If you bypass the standard boost controller soleniod. All that controls your boost is the actuator spring.

6. If you stock soleniod is playing up or not working properly. It may cause no changes in psi pressure. As its not opening the valve anymore to compensate for extra flow. This is common on older cars.

I got this information from "Maximum Boost by Corky Bell"

Its a good book. And it does explain it pretty well.

Not going to write it word for word. goes on for 2 pages.

[Guest 570CK]

little picture for you

From Intake ====R======================= Soleniod

.............................................=

.............................................=

.............................................=

.............................................=

.............................................=

.............................................=

.....................................Wastegate

........................................Actuator

R = restrictor

Ignore the dots

Leonardo will be jealous of my artwork

[DennisRB30]

There are 2 different restrictors that I’m talking about. I even used caps lock to illustrate the point.

Is there a particular part of my post you do not agree with? I’m not sure you followed what I was trying to say. I would be glad to be corrected as long as you give detail as to HOW you think things work. I went out of my way to try and explain the process, you basically just said doing A will affect B because it just does. I’m not trying to have a go at you. It’s just that some things you said didn’t seem make sense.

At the end of the day the actuator spring is the ONLY thing that controls boost. Solenoids and bleed valves are just a way of tricking the actuator by reducing the pressure value it receives.