I've been reading alot of different numbers out there for "stock" boost (psi) numbers for det's. My BB det runs dead on @ 7.5psi, but I'm hearing numbers like 6, 7, 8, 6.5... What exactly is the stock wastegate set at? I have all of my vacuum lines running off of the manifold. I have seen some people using a line off of the stock TMIC piping that goes to the wastegate. Does this make a difference? If the wastegate is set for 7.5psi, then how the hell are these people making "stock" 6psi? Are all boost gauges different? I'm using the autometer mechanical. Anybody???

I've heard 6.5, and I'm pushing almost 7, so I guess it's 6.5

what about stock boost for a T28...???? I just got my car running with this setup and the boost gauge is reading 6 but my friend is telling me is cant be it has to be 7???

From word of mouth(not sure if it is a fact), a BB motor stock boost is set at 6.5psi. Now a T28 is set at 7psi because the stock wastegate actuator is set between 7-9psi. Please someone correct me if I am wrong but I am pretty sure those numbers are correct. Thanks!

The stock boost psi for AWD SR20DET is 6.5, however if you have rotated you compressor housing and put more or less of a load on your wastegate actuator your boost will change a little. The more tension or preload you put on it the more boost and less boost creep you will make. With less than stock tension or preload on the wastegate actuator you will have alot more boost creep and possibly boost a little bit lower (barely).

Originally posted by charlie2020
The stock boost psi for AWD SR20DET is 6.5, however if you have rotated you compressor housing and put more or less of a load on your wastegate actuator your boost will change a little. The more tension or preload you put on it the more boost and less boost creep you will make. With less than stock tension or preload on the wastegate actuator you will have alot more boost creep and possibly boost a little bit lower (barely).


ahh, that would explain the mere 5.5 psi i was making without a boost controller. i have the avenir.

i ran a 13.9@101 on that boost level.

Ok...so why am I boosting 7.5psi? The turbo and wastegate are stock. The only thing I have is a 2.5in dp and 3in exhaust. All I am hearing is heresy (sp?). Does anyone have an answer?

Has anyone here ever made there wastegate actuator adjustable like the GTi-Rs? If not I think it is a pretty worth while modification.

Benifits:
1. Don't cost much to do maybe a $1.00 or so.
2. Up the boost slightly.
3. Your still OEM with no boost controller and boosting more than stock levels (not that a boost controller is bad by any means)
4. Delay the onset of boost creep when the actuator wastegate first starts to open (first you should know that wastegate actuator starts to open up at about half its rated spring presure so if a stock AWD SR20DET is 6.5 psi then it starts bleeding off boost pressure at around 3psi+/- (relaxed/slop/easy/lazy whatever you want to call it spring pressure) until it reaches it stock spring setting of 6.5psi making the turbo work unessisarily (spellcheck). Remember the springs gets harder (more resistance) as it is compressed thus probably making the boost psi more stable and less pron to fluctuate when you shorten the rod lenght. This could probably go on an on about why didn't the factory make it this way in the first place (DRIVEABILITY) but in the name of performance we like that big punch in the gut acceleration or else we wouldn't drive Nissan SR20DETs.

Below is an aide to the adjustment of the turbo wastegate actuator rod. Apparently, most SR20DET come so that the wastegate opens and starts bleeding off excess turbo pressure at about 3 PSI. This can be adjusted up, so that the wastegate does not open until a high pressure is achieved. I would not to go more than 3psi above stock as you still want the wastegate door to still be able to bleed off excess boost pressure to prevent spikeing.

The technique is as follows:

With a pump

What you need is a small pump with a very accurate pressure gauge inline between the pump and the end of the tube where you connect it to the wastegate. You pump in any thing over 3psi becuase that is around when the actuator start to open, maybe 6-8 PSI or whatever you want becasue we want to delay the onset of boost creep so we can build max boost faster, and then adjust the end of the wastegate rod so that is fits back over the wastegate lever, making sure the lever is in closed position (pushed back towards the direction of the rod). Tighten the lock nut on the wastegate lever and replace the circle lip. Remove your pressure equipment and replace regular hose to wastegate actuator.

or

Without Pump

1. Pull the circle clip off the end of the wastegate actuator rod
2. Loosen the lock nut carefully at the end of the rod and turn the end of the rod 1 full time or so that it gets shorter.
3. Tighten the lock nut and reassemble.
4. Take for a test drive and record your new boost psi.

Originally posted by blackb13
Ok...so why am I boosting 7.5psi? The turbo and wastegate are stock. The only thing I have is a 2.5in dp and 3in exhaust. All I am hearing is heresy (sp?). Does anyone have an answer?

Not to be dick but I think I answered your question you just don't have a good understanding of function of the wastegate actuator. You can boost more than stock on a stock wastegate actuator.

0. It's not hearsay (spellcheck) it's FACT
1. What DET do you have?
2. Did you in any way rotate your compressor housing?
3. To understand what I am talking about you need to really understand the function of the wastegate actuator (I mean literally really think about it.)
4. Once you really understand it and how shortening or lenghtening the actutor rod effects boost psi.
5. You'll say NO SHIT that makes sence.
6. Why you are boosting exactly 1 psi more than I can think of 2 reasons possibly.

A) Slight vaccum leak in the line to the Actuator.
B) Slightly bent Actuator rod.
C) Just might be your boost guage is inaccurate.

Originally posted by blackb13
I've been reading alot of different numbers out there for "stock" boost (psi) numbers for det's. My BB det runs dead on @ 7.5psi, but I'm hearing numbers like 6, 7, 8, 6.5... What exactly is the stock wastegate set at? I have all of my vacuum lines running off of the manifold. I have seen some people using a line off of the stock TMIC piping that goes to the wastegate. Does this make a difference? If the wastegate is set for 7.5psi, then how the hell are these people making "stock" 6psi? Are all boost gauges different? I'm using the autometer mechanical.
Anybody???

It is pretty much impairitive (sp?) that the actuator not be disturbed from stock position if you plan on making 6.5psi and no pressure leaks as that is how the actuator works.

Won't a bigger exhuast increase boost?? Just like removing the cat (usually).

Originally posted by Loe Lyf
Won't a bigger exhuast increase boost?? Just like removing the cat (usually).

No, it won't, it has absolutly nothing to do with it, just think about it how would putting an exhaust on increase boost, you have not done anything to the wastegate actuator (THE WASTEGATE IS WERE THE MONEY IS AT THE). But it will increase VE volumetric effiency (sp?) just like CAMS, CAI, PORTING ETC.

Here are 2 ways to make more power with your SR20DET granted both are equal SR20DET examples both with stock T25.
I believe (example 1) is the better way, just imagine when you want to run 10psi for a while.

Example 1.
Stock SR20DET 6.5psi (Air charge not as hot, designed to run this way all day long)
TOMEI CAMS or whatever floats your boat
NISMO Cam gears (geared toward top end as it is already hard enough to laugh with all that tourqe of a stock DET and how a DET falls off in the upper RPM range).
3inch exhaust
probably put down and easy 230whp
Very reliable at 6.5psi, don't have to worry about detonation.

Example 2.
Stock SR20DET 10psi (Air charge a lot hotter then 6.5psi not intended to run this way all day long)
Stock Cams
3inch exhaust
probably put down and more stressed out 230-40whp
Not as reliable at 10psi, have to worry about detonation and how hot it is outside.

Does anyone agree with this, just trying to show a way to have more horse power and reliability.

my boost.. 8 psi at full throttle
2.5 inch downpipe and 2.5 line
t-25 stock of a bb det
sr20de 9.5:1

Originally posted by Nayzan
my boost.. 8 psi at full throttle
2.5 inch downpipe and 2.5 line
t-25 stock of a bb det
sr20de 9.5:1

Thats nice but what are you trying to tell me, that your 2.5inch exhaust is makeing you boost 8psi. I think not, the problem lays somewhere else (if you want to call it a problem?). Thats like saying if you put cams in your going to boost another 1.5psi above stock thats crazy. See I'm not trying to put people down here but alot of YOU don't know shit about turbo's with all do respect because it is fairly new here and it doesn't help that you have someone like JWT to make it work for you. Actually learn how a turbo works not that it just sucks in air and makes a cool sound and alot of power, then you can make an argument if you think I am wrong. I'm not trying to be an asshole I'm just trying to educate LM's that need it. From what I see the Nissan Turbo Community is far behind Mitsubishi, Subaru and Toyota's knowledge of forced induction things those guys know there shit, I'm just trying to make that happen here so you don't have to rely on 3 letter ripoffs.

You're not being a dick. However, all you needed was to post the stock psi and list some kind of source.


Originally posted by charlie2020



0. It's not hearsay (spellcheck) it's FACT. What is FACT? Sources please.

1. What DET do you have? U12 red top det

2. Did you in any way rotate your compressor housing? NO

3. To understand what I am talking about you need to really understand the function of the wastegate actuator (I mean literally really think about it.) I know what the wastegate actuator does. So, what do I really need to think about???

4. Once you really understand it and how shortening or lenghtening the actutor rod effects boost psi. I see your point here. However, mine has NEVER been touched.

5. You'll say NO SHIT that makes sence. Ok...

6. Why you are boosting exactly 1 psi more than I can think of 2 reasons possibly.

A) Slight vaccum leak in the line to the Actuator. Nope, Trust hoses all around with clamps on every nipple

B) Slightly bent Actuator rod. There is no noticable bend at all.

C) Just might be your boost guage is inaccurate. I highly doubt that. It rests at zero and vac is at 18 when idling.

Now, do you think that because of the age of the actuator, it might not be able to keep it at 6.5? I want to know where you got your information from. How do you know the t25 is set at 6.5psi? Can you post a link,sources?

Three letter ripoffs...JWT <- funny stuff.

Originally posted by blackb13
Now, do you think that because of the age of the actuator, it might not be able to keep it at 6.5? I want to know where you got your information from. How do you know the t25 is set at 6.5psi? Can you post a link,sources?

Three letter ripoffs...JWT <- funny stuff.

a wastegate is a resistance spring, if it gets old, it will more than likely lose boost instead of gain it. now, if the wastegate is stuck, then it will just spike, then settle down.

i think there is something wrong with his boost guage.

adding stuff like exhaust only increases the max psi (if possible) your turbo can deliver, if the wastegate DOES open. now, exhaust may gain you power, but not more boost. now, if your gate is closed all the time (max exh energy delivered to turbo) then you may gain boost. see what i am saying?

Charlie,

JWT is a rip off? I call bullshit.

I seen this crap time and time again on this board. And it is simply not true. The JWT ECU is a bargain. Explain the two month wait for one. The guys on this board have to be the cheapest people on the planet. If there was something better/cheaper they would buy it.

I have yet to anyone post up a equally reliable system for a better price. And don't give me that AFC and fuel pressure regulator crap either. Between an AFC, a regulator, and a gauge your close to the price of a JWT ECU, it doesn't work as well, and takes hours to install and tune. A JWT ECU takes about 10 minutes to install. What about the cost of dyno time for tuning another system?

Prove me wrong. Everyone here, not just me, is waiting to see it.

Cheers,
Charlie :)

Charlie,

I'm not even going to waste my time anymore after this post. If you like JWT then you do. If your like me and you like to do shit on your own then good for you. Later

When I make remarks about JWT, it's my opinion don't take it to the heart unless its true. w/respect CHARLIE

Please don't come back with some kiddy bullshit line like. See he won't even explain himself. No, bro it aint like that I just don't like explaining myself to people who can't comprehend that there are others ways of doing things safely. ;)