Whats stock boost for S13 S14 SR20DET

[UNISA JECS]

Sounds like a very simply question but one that isn;t very easy to find a deffinate answer to.

What I do know:
S13 SR20DET
Wastegate actuator has a 7lbs spring so it is either 7psi or higher, now before someone jumps in and says you answered your own question not so fast.

The W10/W11 Avenir AWD SR20DET commonly swapped into the FWD B13/B14/P10/P11 chassis also has a stock wastegate actuator with a 7lbs spring inside, but is boost controlled from the factory to .65bar (9.4psi) IIRC.


What I dont know:
S14 SR20DET
I dunno nothing about that not even what the stock wastegate actuator is rated at with no boost control if any.

[s15specR]

got the same question...bump

[burnsauto]

Sounds like a very simply question but one that isn;t very easy to find a deffinate answer to.

What I do know:
S13 SR20DET
Wastegate actuator has a 7lbs spring so it is either 7psi or higher, now before someone jumps in and says you answered your own question not so fast.

The W10/W11 Avenir AWD SR20DET commonly swapped into the FWD B13/B14/P10/P11 chassis also has a stock wastegate actuator with a 7lbs spring inside, but is boost controlled from the factory to .65bar (9.2psi) IIRC.


What I dont know:
S14 SR20DET
I dunno nothing about that not even what the stock wastegate actuator is rated at with no boost control if any.

stock from the factory is around 10-11 (i cant remember the exact number) with an inline bleed off solenoid

stock for most of the swaps in the US....7lbs.

[UNISA JECS]

Heres a picture for anyone that might be wondering what it looks like that didn;t get a full clip:

http://i167.photobucket.com/albums/u159/zilvia_album/SP32-20080812-094355-1.gif

[Petoria]

With my notch top win I installed my boost gauge It read between 6.7 and 7 psi at stock.

[UNISA JECS]

With my notch top win I installed my boost gauge It read between 6.7 and 7 psi at stock.

I guess notch top is S14? ok so if it is that pretty much tells me that the stockwastegate has a 7lbs spring inside it, now if we can find out the factory boost pressure.

[slidingsky]

S13 red and black top & S14 SRs are rated at 7psi
The Avenir (silvertop/no paint VC) is rated at 7psi as well
The GTiR is rated at 10psi

[FusionR240sx]

yea my red top is @ 7psi

[UNISA JECS]

S13 red and black top & S14 SRs are rated at 7psi
The Avenir (silvertop/no paint VC) is rated at 7psi as well
The GTiR is rated at 10psi

If you are speaking in terms of stock wastegate rating we know that (except for the GTi-R I didn't know that)

But we wanna know what the stock boost is from the factory, if you say its 7psi that doesn;t make much sense because what would be the purpose of the factory boost solenoid

For example:

U12 Bluebird rated at ~207ps journal T25g

U13 Bluebird rated at

W10 Avenir rated at 230ps journal T25g

W11 Avenir rated at 230ps ball bearing 25g

RNN14 GTi-R rated at 230ps journal T28

I imagine none of these boost 7psi from the factory, what would be the purpose of a boost solenoid then.?

[SoSideways]

S13 red and black top & S14 SRs are rated at 7psi
The Avenir (silvertop/no paint VC) is rated at 7psi as well
The GTiR is rated at 10psi

yea my red top is @ 7psi

Are those numbers with or without the factory boost solenoid?

Pretty sure this thread was created to dispel some of the myths or questions surrounding the inconsistent answers that are always giving about the stock boost pressure on the S13/S14/S15 motors.

Most people in the US claim stock boost pressure is 7psi on the S13, because a lot of them don't have the stock boost solenoid on there, or their's aren't working, thus so far, everything "assumes" that it's 7psi stock.

I think Unisa Jecs is trying to PROOF it once and for all, so we can all put it on the records and say "yes, stock is ___psi".

[UNISA JECS]

Maybe I wasn;t clear enough in my first post, my bad.....I just dont wanan see a bunch of people replying that they boost 7psi, we know this already, that just means you dont have the stock boost control solenoid in your car working.

Please read the first post again and then look at whats highlighted in RED about the Avenir.

[SoSideways]

I don't have time right now to look through the S14 SR20DET FSM that's commonly found on the internet as a PDF file, but I'm sure it mentioned the boost solenoid in there.

I just don't remember if it mentioned the default pressure of boost it's supposed to generate if it's working properly.

[UNISA JECS]

I don't have time right now to look through the S14 SR20DET FSM that's commonly found on the internet as a PDF file, but I'm sure it mentioned the boost solenoid in there.

I just don't remember if it mentioned the default pressure of boost it's supposed to generate if it's working properly.

I have the S14 SR20DET FSM on PDF as well with no specs given as to the stock boost pressure, howver I will look again just to make sure.

Same thing goes for the RNN14 GTi-R I have a FSM for that to with the same, no mention of the stock boost pressure, I will look again to make sure as well.

[SHIFT_*grind*]

stock from the factory is around 10-11

Yep. I'm almost certain it's 11lbs for the S13 SR. I'm not quite as sure for the S14.

[UNISA JECS]

You know what im going to ask Matt from Nistune since he is in Australia and AFAIR they sell factory Nissan SR20DET atleast S14 im not sure if they sold S13 out there.

[SoSideways]

Well, I'm pretty sure there were/are members on this board that lived/lives in Japan, so if they could chime in about this subject, that'd be cool.

[slidingsky]

The point of the Nissan boost solenoid is to switch from the low boost and high boost settings. Low boost is 4psi high boost is 7psi.

I didn't know that about the Avenirs.... we really don't get those motors to often so I haven't put that much research into them.

[UNISA JECS]

The point of the Nissan boost solenoid is to switch from the low boost and high boost settings. Low boost is 4psi high boost is 7psi.

Thats impossible, the wastegate has a 7lbs spring, therefore you cannot control boost but at anything but 7psi or greater.

By default if the boost soleniod failed your boost would drop to 7psi via the rating of the stock actuator.

I know that the U12 U13 W10 S13 all have 7lbs wastegate srpings +/- .5lbs

*AWD SR20DET engines are my background knowledge of the SR20DET, I just have never knew for sure the stock boost of any but the W10 Avenir.

[SHIFT_*grind*]

4 pounds is way too low. Boost without a solenoid is 7 pounds; the solenoid can *only* increase boost, not decrease it.

Gah, beaten to the punch.

[s13silvia88]

i have the stock boost ssolenoid in my sr20det its a red top , and it boost exactly at .5bar there for 7 psi

[UNISA JECS]

i have the stock boost ssolenoid in my sr20det its a red top , and it boost exactly at .5bar there for 7 psi

Know if you can prove that it is working 100% and hooked up correctly is another story, not doubting you that its hooked up and all, but for it to only be boosting 7psi makes no sense of having a boost control solenoid at all.

You could disconnect your solenoid and I can guarntee you yoru boost will not drop below 7psi +/- .5psi (for wear and tear of the wastegate)

[slidingsky]

What sense does it make to boost to X Psi if you have a wastegate that is rated for 7 Psi? The real question would be to get something around a 15 Psi spring and then see what happens with a working boost solenoid in place. Assuming that it really is 11 Psi like suggested (not doubting it btw).

[SHIFT_*grind*]

What sense does it make to boost to X Psi if you have a wastegate that is rated for 7 Psi? The real question would be to get something around a 15 Psi spring and then see what happens with a working boost solenoid in place. Assuming that it really is 11 Psi like suggested (not doubting it btw).

It makes perfect sense, because if you have a 15 psi wastegate spring, you cannot boost less than 15 psi.

All a boost controller or boost solenoid does is create a controlled leak so that the wastegate thinks the manifold is seeing less pressure than it actually is.

Stock wastegate actuator is 7 pounds. The factory solenoid creates a controlled leak between the manifold and the actuator so that when the manifold sees 10-11 pounds (pretty certain it's 11), the actuator sees 7 and opens up.

[UNISA JECS]

It makes perfect sense, because if you have a 15 psi wastegate spring, you cannot boost less than 15 psi.

All a boost controller or boost solenoid does is create a controlled leak so that the wastegate thinks the manifold is seeing less pressure than it actually is.

Stock wastegate actuator is 7 pounds. The factory solenoid creates a controlled leak between the manifold and the actuator so that when the manifold sees 10-11 pounds (pretty certain it's 11), the actuator sees 7 and opens up.

Also this controlled leak is not lost to atmosphere it is simply re-routed back to the intake trake between turbo and MAF like it should be since it has been accounted for already by the MAF sensor.

[UNISA JECS]

When you think about all this:

KA24DET @ 7psi has an effective compression ratio of 14.0:1

SR20DET @ 7psi has an effective compression ratio of ~12.5:1

SR20DET @ 9.7psi has an effective compression ratio of 14.0:1

This shows one example why it takes more boost on a SR to make the same horse as the KA all things equal.

Factory boost pressure has to be similar to the Avenir SR20DET from the factory.

[s13Eper]

Stock redtop swap here. ~11psi (autometer) with stock boost solenoid.

[UNISA JECS]

Stock redtop swap here. ~11psi (autometer) with stock boost solenoid.

Ok thats good info, I know most autometer gauges are off about 1psi though, I owned one and about 4 on my friends owned then as well and there were all usually ~1psi high I compared all there gauges this is years ago against my Apexi gauges and the differences where clear to see.

To add to this just called my friend that I swaped a W10 Avenir SR20DET into his B13 Sentra SE-R years ago and I just remember he installed a RNN14 GTi-R T28 journal bearing and he told me the actuator pressure is ~9psi but thats only confirming the wastegate rating.

[SoSideways]

Stock redtop swap here. ~11psi (autometer) with stock boost solenoid.

DING DING DING!!

I think we have a weiner! :bigok:

[Sileighty_85]

Im sure that the S14 Boost level is no Higher than the Red Top Since the S14 still runs 370cc Injectors

I have a video @ home of a RHD BONE STOCK 180SX with a close up on the boost gauge when I was test driving it, I will find it and upload it when I get home... If interested.

If I remember correct I dont think I ever saw it go above .7 Bar

[UNISA JECS]

Im sure that the S14 Boost level is no Higher than the Red Top Since the S14 still runs 370cc Injectors

I have a video @ home of a RHD BONE STOCK 180SX with a close up on the boost gauge when I was test driving it, I will find it and upload it when I get home... If interested.

If I remember correct I dont think I ever saw it go above .7 Bar

Hp rating is higher on S14 isnt it plus has a T28 correct? If so that makes perfect sense.

Try and get the video uploaded if you can that'll be cool.

[SlideWell]

the optional 3 din gauge cluster for the kouki s14 SR reads boost up to .7 bar. and yes, T28 for all s14 SR's.

[!Zar!]

7lbs no solinoid. Which is almost .5bar.

[slidingsky]

I'm still getting mixed signals but most of them say that the boost pressure itself is 10 PSi +/- .5psi for the S13/14 SR

Which would be more reasonable compared to the Avenir.

[UNISA JECS]

I'm still getting mixed signals but most of them say that the boost pressure itself is 10 PSi +/- .5psi for the S13/14 SR

Which would be more reasonable compared to the Avenir.

What I found on the Avenir was threw a japanese translation.

‚ª‚ñ‚΂êƒAƒxƒj[ƒ‹ (http://www.geocities.co.jp/MotorCity-Rally/2549/)

ブースト
ノーマル（０．６５）。ＥＶＣぐらいは付けたいかな？

Translated:
"Boost Normal (0.65). As for about EVC the kana which we would like to attach?"

[s13silvia88]

its for response. with my friends with out the boost solenoid there cars lag in response and boost comming on fast. or early in the rpms. i connected it rite bc i had a front clip and i kno wat wires were connected to it so u jsut extend it...

[UNISA JECS]

its for response. with my friends with out the boost solenoid there cars lag in response and boost comming on fast. or early in the rpms. i connected it rite bc i had a front clip and i kno wat wires were connected to it so u jsut extend it...

It not strickly for responce, however it may help improve responce, but if you were to look closely at the wastgate signal line, inside of it you will find what is called a restrictor pill, this delays the on-rush of incoming air briefly to alow boost to get a head start before being bleed off to maintain targer boost pressure, this lil pill have a big influence on precieved lag.

http://i167.photobucket.com/albums/u159/zilvia_album/SP32-20080812-144824.gif

[SoSideways]

Those pills are like the holy grail of boost control on the twin turbo Z32s.

[Sileighty_85]

Ok Well I can confirm that the Stock boost pressure for the S13 SR20DET is .7 Bar

I'd like to upload the video but there is like 2 mins of crap until the I show the Boost gauge.

[nismo_s14_]

i read and was told:
s13 sr is @ 7psi
s14 sr is @ 8psi
s15 sr is @ 10psi

[Silverbullet]

^ you obviously don't read.

i find it a little hard to believe the stock S14 was able to adjust to 10psi on a T28 from the factory. That yields roughly 250whp.. close to maxing injectors.

[kernel]

I can confirm the stock boost pressure is 7 PSI with this solenoid hooked up.

Both my RHD (180sx 1991 and Silvia 1991) were boosting that and everything was stock.

180sx had a FMIC with cat-back, silvia had cat-back only. That's all.

[Sileighty_85]

I can confirm the stock boost pressure is 7 PSI with this solenoid hooked up.

Both my RHD (180sx 1991 and Silvia 1991) were boosting that and everything was stock.

180sx had a FMIC with cat-back, silvia had cat-back only. That's all.

are you sure its 7psi and not .7 Bar?

My 180SX was bone stock with ONLY a cat back and ran .7 BAR

dont forget about the pressure drop you will encounter when using a FMIC

[UNISA JECS]

I can confirm the stock boost pressure is 7 PSI with this solenoid hooked up.

Both my RHD (180sx 1991 and Silvia 1991) were boosting that and everything was stock.

180sx had a FMIC with cat-back, silvia had cat-back only. That's all.

Again not doubting you that you have it hooked up, but maybe your solenoid doens't work but this goes against having a boost solenoid in the first place if your only seeing 7psi because the wastegate alone will manage a 7psi boost pressure.

[s13Eper]

Just a side note, I have a switch wired between the factory boost control solenoid and the ecu. Closed (on) = around 11psi, open (off) = around 7psi. Stock red top.

[kernel]

I have Defi gauges in both my car and it was .5 Bar

Also, I can't confirm that both solenoid were working but I'm sure I had 7 Psi, no more.

I can confirm that the spool up time was higher without the boost solenoid, I hooked up my actuator directly to the hot pipe and it was a bit slower !

The silvia had SMIC...so...no pressure drop there and still 0.5 bar !

[Def]

When you think about all this:

KA24DET @ 7psi has an effective compression ratio of 14.0:1

SR20DET @ 7psi has an effective compression ratio of ~12.5:1

SR20DET @ 9.7psi has an effective compression ratio of 14.0:1

This shows one example why it takes more boost on a SR to make the same horse as the KA all things equal.

Factory boost pressure has to be similar to the Avenir SR20DET from the factory.

Effective compression ratio is an essentially meaningless number. At least mechanical compression ratio gives you a very rough idea of the ideal thermal efficiency achievable according to the Otto cycle.

A better way to look at the two engines under boost is to calculate the mass of air per cycle at an arbitrary volumetric efficiency.


As for stock boost, I made 205 rwhp with just a turbo back exhaust and stock everything else on my redtop with a T25 at 7.5-8 psi(wastegate spring). I can't imagine stock boost is much higher than that with the BC solenoid if 205 bhp is to be believed.

[UNISA JECS]

I can't imagine stock boost is much higher than that with the BC solenoid if 205 bhp is to be believed.

I dunno, the stock S13 sr20det only has a ~2.25" Dp and 2.25" catback and stock air box so 205ps at .7bar doesn't sound unreasonable but .5 bar might. Ofcourse overhere we usually larger exhaust and intakes so at .5 bar we make what they make at a higher pressure.

[Def]

I'd expect more like 170-175 rwhp if it was actually 205 bhp. I find it hard to believe you'd get a 30 rwhp gain from just an exhaust and the slightly bumped boost that comes with it, but I guess it's not completely impossible.

[koukimonster139]

couldve sworn it was 11psi


who cares tho, stock boost sucks

[Def]

All I've got to say if it's 11 psi, is I feel sorry for those with stock S13s/S14s, as the SMIC takes about 2 seconds of WOT to heatsoak at about 10-11 psi on a T25.

I got nasty detonation on the track with 93 octane, stock everything except the turbo-back exhaust and 8 psi. After 1 lap the SMIC was essentially something good to cook an egg on, that's about it.

[redclaw05]

im rocking a SMIC. running 7 or 8 psi according to my profec B.
stock t28 as well.


hoping to get a FMIC very soon so it can feel the breeze :)

[asiandude15]

Alright we hooked up an autometer guage to my friends car and he has a S14 (from a k's aero) sr20det in his S13. The guage said 5lbs. I was like WTF?!?! Any ideas why cuz the guage is hooked up before the FMIC cuz I wanted to see a direct reading without the pressure drop and I would imagine with the pressure drop through the FMIC setup, if it is really at 5lbs than that would mean like 3-4lbs by the time it gets to the throttle.... Weird

[SoSideways]

Your wastegate actuator could be tired and on its way out.

[jssilc]

i kno this is a old thread but interesting. did you guys ever think the bc could be used to keep the boost consistant. im on stock wastegate on a t25 but on a ka now 4-5gear the boost kinda doesnt stay consistant maybe the bc is ment to keep the boost consist through different conditions.

[TurboStrong]

My stock notch top is stock and she hits 7 pounds.

[Mesarina]

Old thread I know, but just to clarify I have a stock jdm 94 180sx (black top) with boost solenoid, and stock boost is 7psi, no more, maybe you guys doing swaps got an engine with a shimmed wastegate or something...

[cotbu]

Old thread I know, but just to clarify I have a stock jdm 94 180sx (black top) with boost solenoid, and stock boost is 7psi, no more, maybe you guys doing swaps got an engine with a shimmed wastegate or something...
You with only a post count of ten...should do some test. like remove the solenoid from the equation, then log boost if it's 7psi ask yourself what's wrong with this?

unrelated, I have friend that says he was running 10psi. He was actually running 20+ on an s14 bb turbo with 370's. When he looked at his gauge it was 10psi. I don't doubt that. When I looked at the gauge it was 20, then by 6900rpm it was 10psi

your solenoid is probably not functioning or the ecu is detecting something (like over boost) and turning off the solenoid.

[Mesarina]

You with only a post count of ten...should do some test. like remove the solenoid from the equation, then log boost if it's 7psi ask yourself what's wrong with this?

unrelated, I have friend that says he was running 10psi. He was actually running 20+ on an s14 bb turbo with 370's. When he looked at his gauge it was 10psi. I don't doubt that. When I looked at the gauge it was 20, then by 6900rpm it was 10psi

your solenoid is probably not functioning or the ecu is detecting something (like over boost) and turning off the solenoid.

Post count doesn't have anything to do about how much me or you know about cars, I have code 55 on my ecu, I already removed the solenoid from the equation too, hope your friend's s14 is not running 20psi with 370cc injectors ;)

[cotbu]

Sorry about the post count thing, It's not what you think. He has an s13 with an s13 sr20 and a s14bb turbo.

You on the other hand bumped a thread with out documenting your proof that the solenoid gives you 7psi. I no longer even think about testing this theory, since i dumped the solenoid a while ago. If someone, such as yourself does have the solenoid and can document it keeping boost at 7psi or allowing boost to reach 11psi, would put an end to this age old question.

[Solus Christus]

I have a stock S13 Silvia K's and my boost gauge reads 11 psi with boost solenoid.

I'm guessing a motorswap without the boost solenoid will default to the wastegate's 7 psi but a stock JDM Silvia/180 with the solenoid can reach 11 psi.

[LoSt180]

Stock boost for both the S14 and S15 is the same. Approximately 10-11 lbs with the factory boost solenoid in place. With the solenoid unplugged it defaults to wastegate pressure of 7 lbs. It will also drop to 7 lbs if the ECU detects an error. I had an issue were it felt sluggish and wouldn't go past 7 lbs, after scanning with Consult port there was a knock sensor issue. Fixed problem, cleared code, bam 11 lbs and running strong again. The FSM also states the the boost solenoid responds differently based on speed; 'slow' turbo response at slow speeds and 'fast' response at high speeds.

If people have the boost solenoid hooked up and are still only getting 7 lbs, then they have another problem somewhere. For example, I noticed my auto-to-manual wiring specialties harness originally kept showing my car was in neutral. Car felt like a dog, after fixing the neutral sensor wiring, full boost and VCT started working like a champ.

Readings come from my stock Kouki DIN gauges and roughly converted to psi. The gauge reads up to 700 mmHg. Wastegate pressure is right at the middle line, or 350 mmHg (~6.7 psi). Full boost is a little before the 7 line. So I'm guessing ~550 mmHg (~10.6 psi).

I also upgraded to S15 injectors and S15 ECU and boost remained the same as S14 ECU.

Picture of my boost gauge for reference:

http://i6.photobucket.com/albums/y240/lost_180/97-Kouki/s14-sr20det-stock-boost.png (http://s6.photobucket.com/user/lost_180/media/97-Kouki/s14-sr20det-stock-boost.png.html)