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Rb20 And Lag

iz32

By iz32,
in Engines & Forced Induction

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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......

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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."

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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.

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