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Discuss all things tuning in this section. News, products, problems and results.
So ive been watching the DBW webinars and ive heard that you can limit the throttle opening on low rpm and you produce better torque?
How does this work? Is it possible to get a WOT dyno run on a RB25DET with DBW limiting the Throttle opening to 35% until 4500 rpms and possibly get better torque than if the Throttle opening was at 100% all the way?
I had the idea that with the Throttle fully opened we had all the air needed to produce MBT on the cylinder.
NVM, Webinar 138 kind of touched this in the Q&A
Only in vary rare situations (engines with special tuning of intake and exhaust manifolds) will you pick up more power with the throttle partially closed, especially for normal passenger cars.
In general this was only a carby fuel atomization/progression problem, not a gas flow/intake resonance problem.
I mentioned this a few weeks ago - while it does happen in some cases, it seems to be mostly restricted to IR (independent runner) normally aspirated engines, especially with 'healthy' camshafts.
If you are doing a proper map session, you may notice the torque remaining the same, even dropping off, as the throttle is opened at lower rpm - in extreme cases, the engine will even start misfiring and running rough - if this an issue.
I would expect it to be much less common with forced induction, but it is something to be aware of - if it happens to your engine while mapping, it may not be a problem, just the way your particular setup is set up.