.5 bar until 5k revs then .7 bar thereafter as i said on the other post im 100% sure of this mate

 

Thats what I always understood.

 

So for the 2 plus years I have had the car and been running just under 0.5 bar (which I thought was standard) I've been running on the low boost?

 

I assumed it was 5-7psi, not bar. Otherwise how does the car gain 60bhp or more when at stage 1 with the boost at 0.85 bar? Wouldn't expect an increase of just 0.15 bar giving gains like that.

 

I always thought 5-7psi as well. But I cant find an exact answer. Anyone else shed any light on this? ta

 

When I first got mine it was on two stage boost. 0.5 bar up to 5k and 0.7 bar after that, according to the defi boost gauge fitted. After I went to rsp, it made 330 on the rollers at about 0.85/.9 bar on the same gauge.

 

biggunsjoe you are running on actuator pressure, basically your boost solenoid is doing bugger all. Have a look and make sure its all connected up properly.

If you have replaced the pipe with the brass restrictor in it this will also cause it to run at 0.5 bar all the time.

 

I thought it was psi but I think it's bar.

http://www.asknumbers.com/bars-to-torr.aspx

Type in 0.5 and 0.7 and it gives near the figures closer to the standard mmhg gauge on in the speedo


0.5 bar would be 375 mmhg
0.7 bar would be 525 mmhg

Could be wrong though.

 

So I'll ask again, how can an extra 0.15 bar give more than 60bhp over standard? I know that you do more than just turn the boost up to get to stage 1, but those other mods are simply supporting mods, to allow for the boost increase. To go to stage 2 you add another 0.35 bar along with more supporting mods to reach 400 bhp, an increase of roughly 70-80 bhp normally. It doesn't add up. Hence why I'd always assumed it was 5-7 psi, not 0.5-0.7 bar.

 

So I'll ask again, how can an extra 0.15 bar give more than 60bhp over standard? I know that you do more than just turn the boost up to get to stage 1, but those other mods are simply supporting mods, to allow for the boost increase. To go to stage 2 you add another 0.35 bar along with more supporting mods to reach 400 bhp, an increase of roughly 70-80 bhp normally. It doesn't add up.

stage 1 is not just boost increase.
induction
exhaust
fmic
fuelling

allof this leads to cooler air induction, the exhaust gets rid of the very restrictive cat and the map sorts out a very safe standard nissan map.

Very easy to increase the power by this much.

 

0.5 bar upto 4500rpm and 0.7 bar after until about 6700rpm

It takes other supporting mods to make the extra power, they dont support the extra boost as the stock IC and exhaust can take the increase in boost, but the exhaust is restrictive will cause back pressure and excess heat and kill the turbine.... The Intercooler, will suffer from heat soak and cause DET.

The biggest factor in the supporting mods is breathing.... aftermarket exhausts and intercooling provide the flow and cooling to enable the increase, as the colder, denser charge contains more oxygen, more oxygen higher fuel buring rate, add that to the increase in max boost and you will easily see upto and beyond 60hp gains over stock.

 

It takes other supporting mods to make the extra power, they dont support the extra boost as the stock IC and exhaust can take the increase in boost, but the exhaust is restrictive will cause back pressure and excess heat and kill the turbine.... The Intercooler, will suffer from heat soak and cause DET.

That's why I class them as supporting mods, that to me says those parts are needed to support the boost increase, as you risk doing damage without changing them. It's the same as if I just increased the boost to 1.2 bar. I could increase the boost, but it wouldn't last long without the supporting mods required to make it reliable.

 

Standard boost is 5psi low and 7psi on high boost, I have a gauge installed that reads in psi and its taking the reading from the stock position.

 

Strange

Tried 5 and 7 psi readings and the mmhg reading is much lower than expected. :/

http://www.asknumbers.com/psi-to-torr.aspx

 

Steady, does your car have any mods? I assume the standard 2 stage boost is in place? It does seem odd that for a car that was pretty over engineered, assuming that the boost is 0.7bar, the turbo can only take and extra 0.15bar before risking going pop.

 

Sorry, I should have said that is what it used to read.

I have since disabled two stage boost and I'm currently running full stage one mods on an rsp ecu.

I have a blitz dsbc installed now and when I switch it off the reading on it too doesnt go above .5

IMO the hike in power from stock to stage 1 is far too much for it to be just .15 over stock boost

 

I have a hks evc Steady and with it off my boost is also just under 0.5. Im hoping to get a definite answer on this thread. If I was underboosting by 0.2 bar the car would feel slow. It doesn't, it pulls strong.

 

Stock is bar reading, people swap out the R33 actuator for an R32 jobbie, as the actuator pressure on that is 0.8bar and saves buying an electronic boost controller.

 

the actuator pressure on that is 0.8bar and saves buying an electronic boost controller.

Got one on mine.

 

Stock read is not in bar it's in mmHg

nmHg us used because it us self compensating. Ie it is not effected by atmospheric pressure

It's just a Shane the gauge is ****

The stock reading will be low

 

Stock read is not in bar it's in mmHg

Yep.

 

It goes up to 700 mmHg which is over 0.9 bar / 13 psi!!! Mine always went off the scale!

 

I hooked up a boost guage on my stock 96' GTST, no mods. Car put out 5psi on low boost and 7psi on high boost. I have added an Apexi boost controller set to .75bar. Car is way faster then the stock boost setting. Its a no brainer. I'm 100% sure its low stock boost is 5psi then 7psi. Air doesn't lie.

 

Well there you go then, thanks for the info.... tried and tested on a stock set up by DCote... this is now CONFIRMED, we could do with a technical sticky with as must of this ionformation on as possible.

 

Well just to mess it up when my car was completely standard it was 0.5 bar then 0.7 bar on a blitz gauge so not some cheap ass uncalibrated gauge.

 

I'm still not sure on this and have been looking at different websites trying to find answers. This one is about doing rb conversions. It says the rb20 runs higher stock boost than the rb25 and goes on to say the rb25 runs 7psi not bar:

http://240sxfamily.com/topic/8158221/1/

This one is an old link from 2007. It was written by someone called bigchief and also says the rb25 runs 5 psi unti 5k rpm and 7psi thereafter:

http://jdmsource.9.forumer.com/a/high-boost-on-standard-solenoid-rb25det_post54.html

This is from club Nico and also says 5psi to 7 psi:

http://forums.nicoclub.com/stock-rb25-turbo-boost-pressure-t551502.html

This forum and the other bring up mixed results with some threads saying its in bar others psi. I wonder if any of the traders like RSP or Conceptua could comment on this see if they have any ideas?

 

On my mates std 96 GTST we've fitted a decent boost gauge as the stock is dead, and guess what... 0.5 to 5k, 0.7 after in BAR

 

The RB25DET engine manual says to check the actuator too this..

Manual transmission - 51 kPa 385mmhg 7PSI 0.5BAR

Automatic transmission - 36 kPa 270mmhg 5PSI 0.36BAR

Then you got the second stage boost ontop that which currently can not find in the manual.

 

So autos run lower boost than manuals according to the manual?

 

First I heard of that.

 

I never heard that either. Would the actuator not be tested for the most boost it would run?

 

If it's true, then there'd be a part number change on FAST for the actuator off an auto. Which afaik there isn't.