Speed Density

[ultm8mind]

Anyone got this going on in their ride yet? What exactly can it do for me? What are the pro's? What are the con's? Discuss....

[blkonblk2red]

+1 i know two people running it.. i've heard it helps with about 14+15 whp...? both the people i know running it have a stroker motor a 2.3 and 2.4 both funny enough untuned lol

[VIIIrs]

from what i hear you can run VTA and you also have less restriction because it removes the MAF.....maybe we can get some TB input on this.....i'm thinkin about doing it....

[GoBoost]

I have no idea what you guys are talking about.....

[VIIIrs]

LMAO get on EVOM i'm sure TB wouldn't mind making a thread and making it a sticky...

[ryanowarrior]

that ole Andy boy can fill ya in on it also....if he ever gets on here.............

[VIIIrs]

yeah where the hell has he been

[bomjoon]

it costs $$ and you dont need it.

there. thats the answer you need.

[VIIIrs]

^^^^^are you ever positive?

[bomjoon]

lol

yes im positive when you meet me inperson.

ima e-thug.

srsly... you dont need it. the stock ecu is more than what everyday reg tuner needs.

[Evolvedgti]

Joey, your losin it bro!

O you are tryin to e thig. i get it.

[VIIIrs]

oh no we don't need e-thuggery LOL....I know and that's whats bad ass if you already run ecu controlled boost all you need is the IAT sensor right

[VIIIrs]

Joey, your losin it bro!

O you are tryin to e thig. i get it.

u talking to me or is bomjoon joey?

[bomjoon]

ask matt. tofububble.

he can explain it in many different ways that you wont remember after the 1st explanation.

[Evolvedgti]

;)u talking to me or is bomjoon joey?

bomjoon joey, your Joe! ;)

[VIIIrs]

he'll explain you retarded LOL for real!

[bomjoon]

u talking to me or is bomjoon joey?

lol .

[VIIIrs]

Bam!!!!!!!!!!!!!!!!

[1d10t]

Well Bruce, SD measures airflow via MAP (pressure) sensor data instead of measuring the amount of air passing by a heated element in the MAF.
Going SD would eliminate the necessity of recirculation the bov, also eliminates the death feel when you blow an intercooler pipe off. It would allow you to run no filter,a full 4" intake filter or a forward facing turbo manifold. The question is, is the restriction of the MAF robbing HP? Yes, your 4" intake has to bottle-neck to 3" to fit the MAF. But, on the other hand, we are only running 3" exhausts. (mostly). So having a bigger intake, pushing through smaller intercooler pipes, exiting a smaller than intake exhaust. Im not sure if power is to be had. Now maybe with a bigger exhaust? With out dyno sheets or track times its all speculation and theory. I cannot speak for tables in ecuflash, or what it does, if anything at all, for knock and afr's.
I think combination of parts plays a vital role in if it is worth it or not

[EmminoDaGreaT]

There is a negative to SD, if its not tuned properly, as with anything the car will act funny, etc as well as the need to be tuned more frequently w/ changes to the vehicle.

IE MAF's can usually compansate for minor changes as Maps, don't.

either way the evo @ the shop is on SD and picked up around 15 wheel from 412 to 427.

[VIIIrs]

There is a negative to SD, if its not tuned properly, as with anything the car will act funny, etc as well as the need to be tuned more frequently w/ changes to the vehicle.

IE MAF's can usually compansate for minor changes as Maps, don't.

either way the evo @ the shop is on SD and picked up around 15 wheel from 412 to 427.

so basically what ur saying is for more consistancy MAF is the way to go but if your car is basically a track/drag car SD would probably be the best way to go....as well as MAF is more reliable than SD...so SD wouldn't be able to compensate for altitude, or weather changes?

[ultm8mind]

hmmm, think about dat Joe

[TouringBubble]

Some people have already hit some key points ...

You can ditch the MAF which allows for more customized intake/turbo setups. I honestly don't think that the MAF restricts the airflow that much unless it is damaged, but big turbo cars have sucked the MAF screen in and damaged the sensor, so that might hold some water.

For drivability, I really think that MAF is the better solution. The resolution you get with a MAF setup is great as it picks up on very minor changes in throttle and airflow. But, MAF can be finicky as well and depends on many other sensors to really get things right. But, closed loop operation on MAF is far superior IMO.

SD is great for a purpose built car. It's forgiving and pretty solid once tuned. For a track car, you aren't 100% crippled if you lose a IC pipe, and for a drag car SD will handle much higher boost levels than MAF which caps at a certain Hz value. SD also allows the use of VTA bypass valves, which can generally hold more boost and respond quicker than recirculating valves, which, honestly, are designed for better/smoother performance at part throttle.

I haven't worked that much with SD, but the above represents what I've gathered from the research I've done.

[TouringBubble]

And, as far as running SD on the stock ROM, you just need a MAP and Baro sensor and tuning. That doesn't mean it's simple though as Andy and I are learning.

[ultm8mind]

Ok, I am currently open air not recirc. I have done one or two things to my car, but I was just curious if this would benefit me at all. My Evo is my DD until I get my little hatch built and on the road.

Paul do you think SD is for me or am I good with the MAF set-up?

TB, I could probably give you a breakdown of what I have to help you judge also. But not in here for all, LOL.....

[TouringBubble]

The setup of the VTA valve itself affects how badly the car will run. Basically, most bypass valves, when adjusted correctly, will vent a little air at idle. On a MAF system, this can cause a really crappy idle unless you really crank down the tension on the valve to make it close. at that point, the valve may be too tight to vent boost properly on throttle off ... its main purpose.

Some valves can achieve a balance of both, which is fine. So, if you aren't getting compressor stall (a shuttering sound, kind of like an air powered machine gun) when you lift and your idle is acceptable, then you don't have big problems.

Many people think that the rich spike when you shift is the biggest issue of running VTA ... not the case. Thgat just lets you shoot flames all baller-like.

If you do have problems, then I'd suggest using a recirc valve. a VTA valve is not a reason to go SD in my opinion. SD is not something that everyone should switch to with little reason.

[1d10t]

as said above Bruce, MAF is a more accurate way to measure air. Your car being a street car, Id stay MAF. If you were going 40+ psi drag only, then yeah. Good info in this thread.
Although I recommend securing you honeycomb in your MAF. Removing it works too, but its there to steady the airflow for more accurate measurement.

[ultm8mind]

Oh is that why I almost lit Paul on fire before I left, LOL. Paul, we'll have to figure out how to secure the honeycomb player. I'm sure we can figure it out, haha. Well you figure it out and I either wrench or you do it like you normally do, which is way much faster than my ass doing it. I have learned plenty from you Paul and I definitely appreciate you being there for me.

[VIIIrs]

I don't know if you can really secure it you could go with a GM MAF i'm sure.

[1d10t]

people use epoxy. There are threads on it. Glad to be there for you when youre here, because youre there right now for me.

[TouringBubble]

Yeah, a 2-part epoxy bead around the front edges to secure it to the housing.

[VIIIrs]

^^^^werd!

[Drill_Sergeant]

you can also try going to blow-thru method via MAF-T and GM MAF between BOV and TB. I've tried this method and could not keep the ECU from going into open loop during cruise. some people have gotten it to work with great results. but with all the headaches i went through with it, i would not recommend to anyone.

im waiting for the day one of the evom ecuflash gurus figure out how to run the GM MAF natively. i still doubt i will ever make that change. then again, it may have just been a faulty GM MAF since i got it used for free.

[Drill_Sergeant]

Well Bruce, SD measures airflow via MAP (pressure) sensor data instead of measuring the amount of air passing by a heated element in the MAF.
Going SD would eliminate the necessity of recirculation the bov, also eliminates the death feel when you blow an intercooler pipe off. It would allow you to run no filter,a full 4" intake filter or a forward facing turbo manifold. The question is, is the restriction of the MAF robbing HP? Yes, your 4" intake has to bottle-neck to 3" to fit the MAF. But, on the other hand, we are only running 3" exhausts. (mostly). So having a bigger intake, pushing through smaller intercooler pipes, exiting a smaller than intake exhaust. Im not sure if power is to be had. Now maybe with a bigger exhaust? With out dyno sheets or track times its all speculation and theory. I cannot speak for tables in ecuflash, or what it does, if anything at all, for knock and afr's.
I think combination of parts plays a vital role in if it is worth it or not

although the theory "the turbo is only as good as the exhaust" DOES have merit, i tend to disagree.

yes exhaust has a lot to do with spool up. but it's the amount of air the turbo can suck in that ultimately makes the power.

you can have the most optimal exhaust and still not make power because of restriction. a good example would be the compressor inlet restrictors used on WRC turbos.

im not advocating Speed Density, just giving my thoughts on the exhaust size comment. i do however believe if your compressor inlet is bigger than the MAF, you should consider SD.

say your diaphragm is your compressor, lungs are the housing, windpipe/mouth is the inlet- compare sucking in air through a straw and plain open mouth. with this analogy, your asshole would be the o2 dump.

so again, im not advocating speed density.

im only advocating domestic abuse.

[VIIIrs]

ahahahahah 02 dump

[Apex i ITR]

http://forums.evolutionm.net/evo-dyno-tuning-results/458574-maf-vs-speed-density-w-no-maf.html

Good discussion and results from a reputable tuner in CA.....looks like speed density on cars with stock frame turbo's or not going over 35+ of boost don't see any real gains at least for his customers cars. Maybe if he had a few more parts that breathe uptop (like cams) it would make a difference but he is still putting down 460 on a FPRed and SD made no real difference

[TouringBubble]

Abut the intake v exhaust comments ... I have to say that with the huge intakes and exhausts we can shove in to these cars, the head is likely the bottle neck with larger turbos.

But, any restriction you can remove is a bonus. As I mentioned elsewhere, I gained 19ft/lb and 19 whp with my EPM O2 dump (over a Megan SS O2). The "dump" part doesn't really make power ... maybe 2-4 hp ... it's the precise bend that the turbine outlet pipe takes where the power was gained. The exhaust doesn't come through the turbo and smash in to a nearly vertical wall in the O2 housing, which increases efficiency without really needing more "flow.". This is really more about smoothing transitions than just making things larger, which is obvious since this housing restricts down to a 2.5" at the DP flange and still makes power.

So, basically, this is a DEEP discussion.

[ultm8mind]

Good read gents. SD looks like still a work in progress, alot of people are shifting to it but I'll just be last I guess, like I was with the H1N1 Flu Shot, haha. We'll see, I have a while to go until I return, I will keep an eye on this until then.

THANKS!!

[1d10t]

although the theory "the turbo is only as good as the exhaust" DOES have merit, i tend to disagree.

yes exhaust has a lot to do with spool up. but it's the amount of air the turbo can suck in that ultimately makes the power.

you can have the most optimal exhaust and still not make power because of restriction. a good example would be the compressor inlet restrictors used on WRC turbos.

im not advocating Speed Density, just giving my thoughts on the exhaust size comment. i do however believe if your compressor inlet is bigger than the MAF, you should consider SD.

say your diaphragm is your compressor, lungs are the housing, windpipe/mouth is the inlet- compare sucking in air through a straw and plain open mouth. with this analogy, your asshole would be the o2 dump.

so again, im not advocating speed density.

im only advocating domestic abuse.

Its good to disagree. No progress is made without it. I totally agree with TB on the head and majorly the turbo itself, being the "bottle neck", but as to the exhaust, I picture the pulses interfering with turbine speed. The engine is an air pump. Nothing more. In a perfect flowing situation, You would need the exhaust to be bigger than the intake on a turbo car. I think that the exhaust pulses at the turbine wheel have more of a struggling effect on the turbo than a smaller intake not feeding enough fresh air does. Just my opinion. Think trying to fart while constipated.

[ultm8mind]

Its good to disagree. No progress is made without it. I totally agree with TB on the head and majorly the turbo itself, being the "bottle neck", but as to the exhaust, I picture the pulses interfering with turbine speed. The engine is an air pump. Nothing more. In a perfect flowing situation, You would need the exhaust to be bigger than the intake on a turbo car. I think that the exhaust pulses at the turbine wheel have more of a struggling effect on the turbo than a smaller intake not feeding enough fresh air does. Just my opinion. Think trying to fart while constipated.

Thank you flow master. :D

[bigric09]

Bruce... with your setup...

SD would be beneficial once tuned. Honestly, you could switch over with just a flash in the beginning because you are already on a JDM Map Sensor. By the time you get back i will have the tuning side of it covered and understood as i am in the process of tuning mine on SD and helping with 3 or 4 other cars in the area.

So far what i have noticed simply from switching and being basically untuned, the car is a hell of a lot smoother in all aspects. Idle is better, cruise is better, fluctuation in throttle position no longer is felt in the seat, just seen on the A/F gauge. Even as mine is untuned driving around daily, the car acts normal as it did on the MAF, only my AFR's arent as solid, but soon will be.

With what is on your car now, and the plans after you get back.... going SD would benefit you.

[ultm8mind]

Jason, you know for sure I'll be heading up there to see you. Paul my main man in Columbus is wanting to come to, probably take a third guy Terrell with us also, he is piecing together a 2.4l swap now. But you know you'll see my ass when I get off this deployment now that you're back from Korea.