It seems like a lot of the custom EFI set ups use speed density, but most OEMs use Mass Air. What are the pros and cons of each? Can you use mass air with Mega Squirt? I am not trying to stir anything up, just want to learn.
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Mass Air v/s Speed density
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Mass Air v/s Speed density
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Re: Mass Air v/s Speed density
Mass air flow (MAF) sensors do a good job a measuring exactly how much air is in the system, but even the big ones usually aren't large enough for most aftermarket horsepower levels. The sensors are expensive to make compared to just a vaccum and temperature sensor (speed density). So even if you get a large enough MAF for your application, if you decide to step up to more HP, you may need a new expensive MAF. Where as speed density you can put the largest throttlebody you can find (or reasonably use) and as you step up Horsepower (new cam, heads, exhaust, etc) the fuel and EFI side of it doesn't need to upgrade anything (as long as your injectors also had extra capacity early on, which you'd have to upgrade too with a MAF system if you sized them too small for more HP). Speed Density is a lot more forgiving with upgrades.
OEM's use them primarily for emission requirements, to know exactly how much air is flowing into the engine, even before the O2 sensors warm up enough to start providing feed back. And yup, megasquirt has settings to work with them.Escaped on a technicality.
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Re: Mass Air v/s Speed density
Randal pretty much nailed it.
I think the reason why all the aftermarket standalone EFI systems are Speed Density is because it's so easy to make the changes for parts upgrades, there's no point for a MAF really. Also, a MAF can be a huge air restriction depending on the application.
Meanwhile, there are guys out there who SWEAR by their MAFs - mostly megasquirt guys - a MAF is a really awesome way to run a two stroke engine, all the jet ski guys are running them.
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Re: Mass Air v/s Speed density
Originally posted by dieselgeekRandal pretty much nailed it.
I think the reason why all the aftermarket standalone EFI systems are Speed Density is because it's so easy to make the changes for parts upgrades, there's no point for a MAF really. Also, a MAF can be a huge air restriction depending on the application.
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Re: Mass Air v/s Speed density
Originally posted by dieselgeekRandal pretty much nailed it.
I think the reason why all the aftermarket standalone EFI systems are Speed Density is because it's so easy to make the changes for parts upgrades, there's no point for a MAF really. Also, a MAF can be a huge air restriction depending on the application.
Meanwhile, there are guys out there who SWEAR by their MAFs - mostly megasquirt guys - a MAF is a really awesome way to run a two stroke engine, all the jet ski guys are running them.
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Last edited by BKBridges; April 18, 2011, 08:54 PM.www.FBthrottlebodies.com
Bruce K Bridges
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As was mentioned, SD gives you a lot more freedom in packaging the intake system. With blowers, turbos, stacks, etc. you are not restrained by a MAF.
(Why is stacks repeating? I only typed it once)Last edited by Arrowhead; April 20, 2011, 05:35 AM.
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