Is Speed Density tuning required for under 400HP street driven cars

[Td-d]

I can add my 2 cents, coming from a place of experience having run SD for a while on my '09 STI.

Firstly, I don't understand why this debate becomes so ideological godstruth, we are talking about a fueling system! And MAF and SD are not the only ones, incidently. Google up Alpha-N. Each has advantages and disadvantages.

Personally, if you're not going big, there's little point to SD - it will be more effort that it's worth. MAF is very versatile at dealing with varying environmental conditions such as temperature and altitude. With SD, especially on vehicles not designed for SD from the ground up, you have to tune the various compensations very carefully, and the hardware (if left stock, in particular the IAT sensor) is not ideal. By the way, there are a number of Subarus that ran SD from the factory (mostly Legacies and Outbacks) - including a very obscure 2001 16bit rom that I recently disassembled which had all the mapping axes in MAP sensor voltage. Real pain in the arse, but I digress.

Once you start going for serious power, a MAF implementation has it's drawbacks. Yes, you can increase the intake to accommodate - but your low end and idling will suffer, and tuning it will be a major pain in the ass. Ask me how I know. A blow-through MAF will also have it's challenges with respect to tuning.

The best of both worlds is using SD with MAF blending at lower airflows. This has been available for other Subarus from both open source and COBB for a while. Just saying

[Circuit Motorsports]

Originally Posted by Td-d

The best of both worlds is using SD with MAF blending at lower airflows. This has been available for other Subarus from both open source and COBB for a while. Just saying

Agreed!! Just a note that EcuTek has also supported SD/MAF blending for a while now on the 86 platform. It's extremely useful and allows more MAF resolution for idle/cruise, and SD for high flow.

[FA20Club.com]

And it does allow the use in hybrid for by setting transition point based on load, manifold pressure rpm etc. This was you are still able to use the MAF for lower boost levels with better idling characteristics and cruising drivability.

[Acree]

My previous car was an Evo IX with a built 2.4L running the stock MAF sensor. It put down 556hp on a mustang dyno. I did speed density for about 6 months, but it's more trouble than it's worth in my opinion on that platform. SD has nothing to with horsepower levels but the limitations of the platform. It's been proven by a majority of members here that MAF does just fine for 400+ hp.

[vgi]

@Circuit Motorsports @FA20Club.com that EcuTek note is worthless for non-EcuTek tuners: the license (which payed by car owner but actually owned by the car) owners can't make any changes, not even change the idle rpm themselves. So better say that you can do it (if so) once customer pays EcuTek for license and you for the tune.

[DeliciousTuning]

Originally Posted by vgi

I would like to bring back a lot of useful information that has been removed from one the threads.

Some tuners are saying that Speed Density tuning is required for high HP cars. Some others say MAF based tuning on modern cars is sufficient for most people goals.

So let's say for an average Joe with HP goals for under 400HP with no plans on building engine and street driven car, would Speed Density tuning be needed or provide any benefits?

Here's some info:
http://www.pcmforless.com/index.php?...ning&Itemid=56
http://support.moates.net/theory-speed-density/

Hi,

Nice to see the question that we (EcuTek Tuners, including myself and OFT) should have started before the "other" debate. But I think the question should be rephrased a little bit. It is not about whether Speed Density is required below 400hp but what the benefits and drawbacks are of both systems at power levels for both systems.

Saying one is not needed at all below a certain level and placing an example of a scenario that is good for some people but not everyone is pigeon holing the question before the debate begins. There are scenarios for both and that is where the questions of Speed Density versus MAF should be discussed. If you would like to discuss those differences I am interested.

Here is a thread I have started as a wider discussion.

http://www.ft86club.com/forums/showt...16#post1366216

Cheers,
William Knose

[SirBrass]

So what are the benefits and drawback of MAF and MAP (speed density)?

[FA20Club.com]

Might want to jump into the new discussion thread lots of valid information there.