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Boost in Neutral??

MaXiMuS007

By MaXiMuS007,
in Engines & Forced Induction

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MaXiMuS007 Mentor

MaXiMuS007

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I had heard it was load related but I don't understand what that means... don't a certain amount of revs mean a certain amount of air is flowing in and out of the engine (hence spooling up the turbo), loaded up or not?

I was asking b/c I was talking to a mate about why auto's are better than manuals and he said that the stall converter in an auto allows boost from launch (true)

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GunMetalR33 Mentor

GunMetalR33

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I think this is how it works:

The computer will dump in more full under different load point on the fuel map. Therefore when you are in neutral there is no load on the engine so not as much fuel therefore not as much exaust to spool up the turbo...

Launch control on the other hand retards the ignition so the fuel gathers and explodes in the exaust manifold with creates the flow to spool up the turbo...

Correct me if iam wrong...

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Kinks Grand Master

Kinks

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Retarded ignition means that the combustion has less chance of doing useful work, so it will either burn at the bottom part of the compression stroke or once the exhaust valve opens. I've heard that retarded timing can burn your valves, but probably only on older engines.. But yes, retarded timing means a given fuel/air mixture is doing less useful work on the engine and therefore you can use more air/fuel to run at the same point (which is fine if you are in neutral and want your turbo spinning, but useless if you want to accelerate).

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Gson Enthusiast

Gson

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JIMX

"I can get plenty sideways without boost and fat 255 tyres :) Of course boost picking up soon after launch helps it stay sideways, but I've never needed it off the mark."

well as soon as the clutch is droped there is Load...... Thus boost!

thats if the clutched is droped when the rpms are at a good level!

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Cecam Enthusiast

Cecam

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Well if you give it a quick rev you will generate boost as the engines temporary loaded accelerating its own rotating mass, but thats very short, so thats why you hear the bov when you give it a quick stab... which can make you launch abit harder if you time it right... autos have boost because of the resistance/load from the torque converter...

I know of a few conversions where a rb20det turbo and manifold has been fitted to a rb25de (changed ecu and injectors obviously) and that made boost at idle.... looks weird when you go to take it for a test drive and the gauge is sitting at 5psi while its just idling away...

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JimX Grand Master

JimX

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you just said that you can get plenty sideways without boost!!

just commenting that most likley it is With boost!

 

cheers:)

Oh :) Well, the initial wheel spin happens without boost, and I daresay it wouldn't really need boost to continue (although boost makes it easier). So although I am getting boost by a certain stage, I doubt it's absolutely required.

Any NA SKyline owners want to confirm or deny that?

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