charlie_pank Posted April 15, 2005 Share Posted April 15, 2005 My friend has a supercharged system in his car and is trying to sort out the fuelling. The system he has works off MAP rather than throttle pos, as I've been sorting out the fuelling on Kermit recently (in case you hadn't noticed), he asked me about his set up. Thing is I don't know how "load" is related to MAP in a forced induction system - can anyone shed light on this? Link to comment Share on other sites More sharing options...
Myles Posted April 15, 2005 Share Posted April 15, 2005 I'd expect (crudely) MAP to increase with load, but that's not very helpful. Project Scope-Creep is underway... Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
charlie_pank Posted April 15, 2005 Author Share Posted April 15, 2005 It's a start, as I wasn't sure what the effect of the supercharger would be on the MAP, and wondered whether there are some weird interactions going on in the inlet manifold meaning that maximum MAP is not actually at WOT... Link to comment Share on other sites More sharing options...
Myles Posted April 15, 2005 Share Posted April 15, 2005 Mmm - I'm making this up as I go along, but... ...the boost provided by the supercharger is (presumably) going to rise with revs - and so (presumably) will MAP. But load can vary with revs (nat-asp: light throttles to maintain certain revs on the flat, more throttle required to maintain the same revs on a hill...)... Oh dear. 😳I'm not qualified to comment really. You want someone like DW/Oily/Bill S, I'd guess. Project Scope-Creep is underway... Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
Joe 90 Posted April 15, 2005 Share Posted April 15, 2005 MAP is an abbreviation for Manifold Absolute Pressure, and as a first approximation fueling is therefore going to be proportional to MAP. This simple relationship is why many people prefer MAP over TPS, which invariably has a non-linear relationship. The problem you may experience in a supercharged application is that not all MAP sensors will accept pressures above 1 atmosphere, and you may need to source a MAP sensor which is linear up to your maximum boost pressure. SEP field working, not spotted in 103,300 miles. Some photos on webshots, updated 25 Jan Link to comment Share on other sites More sharing options...
Bill Shurvinton Posted April 15, 2005 Share Posted April 15, 2005 In fact, for a non-hairy engine MAP is directly linear to load. PV=nRT is the ideal gas law. For an engine you need to add the volumetric efficiency to that. So at 1bar (atmospheric) to 2 bar, MAP doubles, so fuel doubles (the ECU should automagically sort out density changes due to IAT). Very easy if you look at it the right way. Oddly people who understand TPS systems have real trouble with speed density and vice versa. which ECU is it? Link to comment Share on other sites More sharing options...
charlie_pank Posted April 15, 2005 Author Share Posted April 15, 2005 Bill it's a Wintec2 - he showed me the software on his work PC - it made me so happy to have an Emerald. To the untrained eye, the Wintec looked feindishly complicated. It seems to be driven off a target AFR rather than one being able to directly determine fuelling at each load/speed site. Therefore I struggle to see how it can operate effectively without a wideband 02 sensor (perhaps that's what they mean in the documentation by an "HEGO"?). Link to comment Share on other sites More sharing options...
Bill Shurvinton Posted April 15, 2005 Share Posted April 15, 2005 Actually the TEC is a fine ECU, very popular all over the world. It has a LOT of features which is why it is confusing. For example the alpha-n/speed density blend feature is really nice. They were one of the first to put in autotuning. A wideband (a HEGO is not a wideband BTW) would speed things up enough. Suspect 20 mins with the manual and i could work it out. Link to comment Share on other sites More sharing options...
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