As the title implies, will ECU+ have a speed density option and when would it probably be avliable, it's either i get a MAFTpro now or a ECU+

 

I'm in the same boat as you^^

 

I think, in general, that using a mass-air sensor is pretty much always better than speed density. When you do speed density, you're mathematically calculating what the air flow should be, given temperature and pressure. When you use a MAS, you're measuring what it is. For that reason, I've been thus far concentrating on supporting the GM MAFs. Right now, Ivan_C is testing out support for the GM 3.5" MAF on his car (in blow through mode).

With that said, if lots of people really want speed density, there's no technical reason I can't do it. Probably won't be short-term, though, as I'm trying to plug through all of the other features that folks have asked me about. Lots of cool stuff in the pipeline!

Tom

 

So you do have a blow through mode with a 3.5 maf ready to be implemented right? I still don't like the idead of it's restrictiveness

 

How much HP are you planning on running? If a 3.5" MAF isn't big enough then something is seriously wrong. How much airflow can the stock MAS flow before it starts breaking up, I'd think it probably flows enough for 90% of Evo owners. My unhacked MAS on my 2g eclipse is handling 50 lb/min fine and I also have the option of hacking the MAS if I ever need to.

 

Right.

Do you have any real numbers, or are you just sorta anti-any MAS? As I mentioned in a prior post, using a MAS is really the best way to go IMO.

Tom

 

Uh...how could it be restrictive if it's bigger then your intercooler pipe?

 

I have seen 3" GM MAF cars making almost 800 HP to the wheel. yup. 3.0
Actually Im just now tinkering with a 3.5" in blow-thru setup (with a Greddy Type-R VTA BOV) also. If this works Im sure it will not be a limit for whatever I can throw at it(in term of turbo).

 

I agree with Tom in his above statements, MAF's are great for everything (except when you blow off an IC pipe.)

People are riding a little MAF delete bandwagon, which could be a problem for a couple reasons
-minimal gains
-MUST COMPLETELY retune the car for speed density if you want it to run like stock

Seeing as most people with ECU+ have a stock turbo, the marginal gains for having a speed density option from Tom's perspective are probably minimal.

 

OK,

I'm gonna go out and look like an *** hat. But can someone expalin speed density to me?

 

I would agree 100% a blowthrough setup is the way to go.

Badevo, Speed density works with 2 variables....MAP-Manifold Absolute Pressure and IAT- Intake Air Temp.

The IAT sensor goes just before the throttle body on the UICP messuring the temp before it hits the MAP sensor which then decides how much fuel to add.

 

Speed density uses air temperature and pressure, along with a VE table to estimate air flow. So if I did this in the ECU+, you'd remove the stock MAS and add an outboard MAP and air temperature sensor. The big variable is the VE (volumetric efficiency) table, which is this big table that specifies how efficient the engine is at some computed level of air injestion and TPS. The VE table varies based on mods, and is pretty tough to get just right. Seems like a lot of hassle just to remove the MAS to me, especially when in the end, you just have an estimate of the air flow. With a MAS, you measure the air flow directly, which is more accurate and repeatable.

Tom

 

No hat on your ***; it's a valid question.

Mass air metering uses some kind of measuring device to measure the ACTUAL QUANTITY of air entering the engine. It's very accurate, although there is always SOME kind of restriction in the airflow.

Speed density metering uses known quantities -- the displacement of the engine -- to calculate the mass of air based on other varaibles, meaning the speed of the engine and the density of the incoming air. That means there's no need for any kind of restrictive air meter, just a pressure sensor at the manifold. But measuring correctly can be tricky, because fluctuations in local pressure can throw off the total calculations. That is, if the pressure is rising and falling quickly, the motor may average out to a certain air flow, and not inject the exact amount of fuel at a given instant.

I'd say the majority of turbo cars use mass air, but some (like the Dodge SRT-4) use speed density.

Oh, and VE means Volumetric Efficiency.

--Dan
Mach V
MachEVO.com

 

What size is the stocker MAF? It doesn't look that small to me, but I bet going to a 3 inch or 3.5 inch would be damn near as good as removing it all together.

I just need a solution for bolting the GM 3 inch MAF to my car, anyone have a how to or a parts list of what's needed etc?

Who's running 3 inch that I can talk to? =)

 

You'll need the MAF (now available here on the ECU+ order page at our site), , plus a 3" K&N-type filter. Put the GM MAF on the end of your turbo intake pipe, and the filter on your GM MAF. Clamp in place. Brace the MAF/filter assembly so it doesn't rattle around. Done!

--Dan
Mach V
FastWRX.com