Pb82 Ronin

Because...weather. And load %. And inlet/intake air velocity. And topography (hills and mountains). All that matters when tuning...especially for drivability.

He may be "fine," but it's in NO WAY ideal. A MAF car can adjust fueling requirements based on the above situations. Speed density is a one size fits all scenario. If anything is different than when the tune was dialed in, the tune is no longer ideal. Is it "safe?" It can be...but you're going to have to leave a ton on the table to make a speed density tune safe in "all environments" and then, you're down on power compared to the MAF equipped car. Speed density is quite basically the beginning technology of the fuel injection replaces carburation changeover back in the 80's. It's inferior to Mass Air. PERIOD. Does speed density work? Yes. Can it work in all fuel injected applications? Yes. Can you use it in a turbo application? Yes. Should you if you care about your cars pure performance? No.

Rkreigh

no doubt maf adds a level of additional gps airflow measure and adds to the precise nature of the tune based on that input but what is the upper limits of a MAF based system?

I'm running around 900 hp in a twin turbo blow through application and I don't know of a MAF that will support that. are you just scaling the inputs in the tune and still using it?

bigger maf? thanks!

Rkreigh

look up the turbonetics numbers off the turbo and you should see an AR stamp on the turbine section and the compressor specs based on the t76 available turbos

for lower boost applications and not winging the motor way up in rpms you will get a sizeable bump in torq and running 10 psi or so it will be fine

I sure would look to get the car as recommended to a good tuner. Injectors are a bit small for my taste and running lean up top is no bueno

stock pistons don't like detonation either (nothing does) but the hypers will bust ring lands quickly when rattled

nickalltogether

This is absurd. You have an IAT sensor in conjunction with the MAP sensor. With those two sensors you can correctly scale for elevations, density changes due to weather, etc.

Saying speed density is the beginning of fuel injection is also pretty ridiculous.. maybe in the Mustang world where speed density came on the 5.0s before they went fuel injection.

Turpid porpoise

Pb82 Ronin

IAT that only gives temp data, and a MAP that only gives pressure...but you're assuming volumetric efficiency, which can change a great deal especially in a forced induction application.

Look I don't want to get into an web bashing session over something this trivial. SD provides less information to the computer than a MAF car. End of story. Yes people can and have used SD with success stories. But to tell people that it's an "upgrade" over MAF is just wrong.

jimbos'ss

VE is derived from airflow, RPM and IAT. SD is derived from pressure, IAT and RPM and VE. MAF isn't that much better, maybe slightly more accurate but prone to having issues with range and placement. It has issue when flow over the sensor is not laminar something a MAP sensor will never have. It has issues with range as the air mass limitations of the 0411 PCM are hardcoded at 512g/sec and 12k hz. Now you can always go to a larger MAF but you lose resolution by doing so. In the end SD is the preffered method on these cars for a reason.

Pb82 Ronin

So spend thousands if not tens of thousands to go turbo and don't pay $500 for a bigger, better MAF? Sure, makes sense if you don't think about it.

Turpid porpoise

The stock ECU is hard coded for 512 g/s and 12,000 HZ, if you go with a larger MAF you lose resolution. Speed Density has become the route of choice for this chassis due to the PCM limitations. Unless you want to spend thousands on a standalone ECU speed density is a far better option.

aaronc7

This thread has been derailed pretty good already....but in my experience, the biggest disadvantage to SD is that any sort of engine airflow modification (intake, headers, anything) will require a VE table update, which makes sense, as that mod is changing the VE of the engine. A MAF since it's measuring airflow directly, as long as you're not changing the intake/TB, stuff immediately around the MAF, it will handle those mods much better and fueling won't be way out to lunch.

It's easy to see why many prefer SD due to the stock PCM memory limit of 512 g/s. Yes, you can scale the injector and other tables to trick the computer and put in a card style MAF in a larger tube. Most just prefer to go SD and with a proper tune, it will be able to handle changes in temp and air pressure just fine. If not then you probably need to tweak some sort of VE vs IAT table, or the IAT was placed in a shitty location.

At the end of the day, many ways to skin the cat, do whatever you like best or have had best results with.

Also the idea that speed density is dead..... I have two newer 2015+ turbocharged cars and both are speed density tuned from the factory. I'm sure the power and logic of these newer ECUs is lightyears ahead of what we have here, but the concept of SD is surely not dead yet.

NosLaser

Please don't listen to anything Pb82 is saying.

NosLaser

I have one car in my garage with almost 1600rwhp and it is very much speed density and has better driveability than my mass air car

Pb82 Ronin

So in hoping to actually HELP the OP. Your car should be retuned in any way possible that brings you to your desired goal. AFR in the 10's (at any PSI) on gasoline isn't ideal. I could care less if you tune it using stone tablets, ice cream trucks, or freaking drones...but it should be re-tuned.

NosLaser

This you can actually listen to. It should be retuned.

stevieturbo

What a load of bollox.

C5 Kirkland

Let's get back on topic. Front or rear mount turbo? With your setup, you should be good to run AT LEAST 700rwhp (crank up the boost!) before you will need to start spending more money.
BUT like the others have said, if you don't want to buy HPtuners and tune it yourself, find a local tuner that has experience with SD tuning and discuss with him/her what you want done.

BLOWNBLUEZ06@RKT Performance

I disagree mass air is always better, even when it's within the range of the sensor. If you had your motor tuned SD and the efficiency and drivability was worse, it's time to find yourself a tuner that knows what they're doing.

BLOWNBLUEZ06@RKT Performance

Definitely SD
at low boost levels, 12.0 is absolutely fine. I'm a big fan of meth injection when it's set up properly.

Rkreigh

Brent you always come through with solid advice and I feel it's time to say THANKS

I'm looking to go direct port alchy injection on my ttix. I've notice that fuel distribution for the alchy at higher volumes doesn't do so well and tuning with another gent that had a big blower and alchy with two nozzles in the up pipe the front cyl ran leaner and the rears cyl running too fat

it was pretty obvious it was fuel distribution as on the injectors without the alchy all egts were good

we went direct port and the egts really evened out and the car was smoother and made more power on the same alchy flow.

Not sure what is the best direct port kit, I don't like those hard plastic lines much and I'm looking for a bit more quality

let me know if you recommendations/thoughts thanks~!

Turpid porpoise

Take a look at ProMeth, they offer direct port kits for most size engines that only require you to bend a few hard lines.