Jump to content
SAU Community

Rb20 And Lag

iz32

By iz32,
in Engines & Forced Induction

 Share

Recommended Posts

iz32 Community Regular

iz32

Posted
Posted

could small shots of NOS be used in the lower RPM range to bring the turbo on earlier or perform a little better between 2500-5000rpm?

just a general though and not knowing or experiencing nos setups at all

Im thinking using standalone ECU spare outputs to control it but with the rpm range and how its to be used, im not too sure about.

is it simply nos on/off via electro/mechanical switch or can you implement incremental spray increases/decrease to tie it in with rpm/vac pressure/afr..?

im also thinking the tuning side would be a nightmare between the nos off - turbo on boost rpm range.

anyways, its just some food for thought......

Link to comment
https://www.sau.com.au/forums/topic/240121-rb20-and-lag/
Share on other sites
clip14 Rising Star

clip14

Posted
Posted

yes a small shot of nitrous can bring on boost a lot quicker.

nitrous is used in drag cars to spool the large turbo's off the line (the ones which do not use antilag) much healthier for the turbo and cost effective as well given that these type of cars only spend a few seconds on the bottle - throttle plate is left open for the remainder of the run so the turbo does not come off boost.

it is not a stupid idea like some people have dismissed.

the tuning side of things is not as complicated as you might think.

nitrous has is an expanding compressed gas and simple thermodynamics will show that this drastically decreases the intake charge and cylinder temperatures reducing the likelihood of detonation.

a wet nitrous system injects fuel as well as nitrous into the intake charge (on top of the fuel injectors). since the oxygen content in combusting nitrous oxide is a set ratio, the amount of fuel injected in a wet system will match the amount of nitrous injected, resulting in no change to the fueling maps of the engine ecu. timing here could be an issue, as the timing maps can be load/boost dependant, but again due to the decreased cylinder temperatures, less likelihood of detonation due to advanced off boost timing. boost will come on and timing will be pulled anyway.

in terms of nitrous control, a separate map can be used if your ecu is advanced enough/has the capability. many top of the line ecu's such as the very expensive autronic and motec do have a lot of tuneablility. simple method is to use a simple position sensor on your throttle/accelerator pedal i.e. at 100% throttle (push switch on the foot well floor) or any percentage of throttle opening (wired into your TPS or other position sensor) to activate the nitrous. a rpm based nitrous activator will result in an empty bottle quickly i assume.

you theoretically could wire into a vac/pressure source, and trigger when your intake plenum see's atmospheric pressure (which theoretically is when you have the throttle wide open or full engine load) but there are situations where this will activate when you dont want it.

target afr is just way too complicated - engines under cruise conditions run lean, on boost, a lot richer. not sure how you'd work this one.

here's a real world example for all you haters (albeit an extreme but you get the point)

"To put it into perspective, the Boostlogic drag car ran a 13.9 @149mph without nitrous, and a 7.86@187mph with nitrous, but we only sprayed for two seconds out of the hole. Granted, that's taking everything to an extreme (GT5591+225 shot) but nitrous makes any lazy turbo into a totally streetable one."

Link to comment
https://www.sau.com.au/forums/topic/240121-rb20-and-lag/#findComment-4193665
Share on other sites
Butters Experienced

Butters

Posted
Posted

My Rb20 on NOS vs some other engines around these parts.

Had 75 shot of gas and made of peak of 250rwhp with stock turbo.

http://spreadsheets.google.com/pub?key=pHf...mp;output=image

As you can see not much touches it in the 3000 - 3500 rpm range.

Link to comment
https://www.sau.com.au/forums/topic/240121-rb20-and-lag/#findComment-4197660
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • TurboTapin
      Why am I hitting a power wall with my stroked RB25?

      By TurboTapin · Posted

      I'm an idiot, my intercooler is rated for 1000hp. I had clicked on the wrong product. Knowing the delta P would be nice, but I'm doubtful I'll do it. Now as for an EMAP, that would be great and I'll get around to it eventually but from my findings in my last post, I'm considering a turbo swap now. 
    • TurboTapin
      Why am I hitting a power wall with my stroked RB25?

      By TurboTapin · Posted

      You sir, big win tonight. Precision never supplied compressor maps in the past and Idk when they started, but it seems they only offer for a few of the older gen2's which is exactly what I have. I punched in some numbers and seem to have gone with the wrong turbo. 600-700whp isn't in the most efficient area and is close to the choke line. 800whp is well off the map. Punching the numbers into a 68mm gen2 turbo map is bang on in the center. Here I was thinking going smaller would shift the power band down, but in reality it would just make it so much worst due to my rev limit. I would have never thought. 
    • Dose Pipe Sutututu
      Why am I hitting a power wall with my stroked RB25?

      By Dose Pipe Sutututu · Posted

      Increasing overlap will bring the torque down earlier (and make your idle sound sick lol). Worth a shot (if you dyno time) to experience a bit (providing you are confident your valves won't kiss your pistons). Is to just take off 5 degrees across the boosted area of the map, and then retard the exhaust cam let's say, 3 degrees at a time and then overlay all the runs with VCT on all the way and VCT off as soon as you make positive pressure. Ideally you would have a total of 6x overlays to looks at 0 exhaust & VCT off once manifold pressure is +ve 0 exhaust & VCT on all the way -5 exhaust & VCT off once manifold pressure is +ve -5 exhaust & VCT on all the way -10 exhaust & VCT off once manifold pressure is +ve -10 exhaust & VCT on all the way Just leave your O2 wideband closed loop on for all of the boost area & RPM, and hopefully there isn't too much fuel correction needed and the Haltech is fast enough to compensate (I do this, then apply the correction to the main table). Getting that overlay data should give you a good indication of what to aim for.
    • PranK
      iPad gauge cluster

      By PranK · Posted

      So, my main limitation here is that the car does not have an oil pressure sensor by default, just a switch. As part of my tune I bought an oil pressure sensor upgrade so I now have access to oil pressure levels and logging rather than just the boolean behaviour of the switch but this means I need to use the tuning app to display this value. So, this rules out using any other app on the iPad. The app will also flash when pressure drops which is a nice feature. I have replaced the centre screen with an Android one, which is awesome for Android Auto, but I think it might be too far away and out of my line of sight. I might add some gauges to it this weekend and just see. I guess if its just temp and oil pressure I can make them massive! 🤣  
    • CRSKmD
      R32 Sedan - Grip and Drift (have my cake and eat it too build)

      By CRSKmD · Posted

      This is what the look like normally. Except we only got the 2 doors locally
×
×
  • Create New...