stock mas limit finally found?
 

some of you may have been following my progress, I've recently dyno'd the car at 700awhp on a dynojet and with increases in boost from 38psi to 45psi, only lower rpm torque increases a little, not the high rpm horsepower, a sign that there is a choke point. Increasing timing also does not make a significant improvement.

I'm interested in going with SD or a MAF-T to answer the question once and for all, how much horsepower can you make on the stock MAS.

If someone has a MAF-T intake setup I could borrow I'd be willing to spend some time dialing the tune back in and seeing if it helps reduce the restriction enough to increase the horsepower. I figure that's the quickest way to get the answer and to see if SD experimentation on the stock ECU is worthwhile for a car at this level.

Any logs? Just curious what the 2-Byte maf frequency looks like.

700 HP through that little guy is impressive. The gains of getting rid of it may be even more impressive though.

Well I've seen 8's out of a GM MAS setup.

Actually I already did the math for your car, at 38psi with no MAF it should be worth about 40-45whp. This is based on a car that is not octane limited at xx boost. Like 0xDEAD said, there are plenty of DSMs running around 750-800+ (I think of Hal Landry) with a 3" GM. DSM25psi made 762 on a Mustang (for what thats worth compared to a DJ) so there is plenty to be had.

I would switch to SD and get it over with, its the easiest overall since all you change is the tune and a MAP sensor vs having to do a different upper pipe. I imagine if you were going to leave it drawthrough you might gain some but not as much as blow through.

I didn't think SD was ready for this kind of boost

I don't log airflow, don't need it for tuning.

Well its kinda ready for any boost level any engine can take. SD works on MAP sensor voltage. How you tell evoscan to represent that voltage in the map is up to you and your skills. I know a couple places that sell 100psia MAP sensors. So as long as you can keep it below 85psi you should be ok. If you need to run more boost let me know and I'll help you source a larger sensor. :lol:

Roadspike was saying something about the 5bar pressure sensor not being sorted out yet with the stock ecu...maybe he'll chime in on that obstacle.

Its sorted for the most part I simply atm have slight tunning issues at the low load and rpm end of the spectrum where the gradiants for VE are the highest. Right now i have a slightly rich cruise issue at about 50-60 load. Nothing a few tweaks of the map and RPM VE wont sort out over time.

I'm sticking to a more 1:1 map kPa vs load rather than the scaling your car is doing where 300kPa would have been more like 360 load. In the end your load will go down on this rom so you don't have to scale it out so high. If you want its easy enough to change the load value to something more like your car is tuned with already.

I'll give you my rom setup for the 5 bar if you want chris just shoot me an email in pm. You're going to have to sort out the VE on your own car anyways since with the big head and turbo its going to be more efficient than my personal car.

Notables:
Car uses a 5 bar kalvico sensor good up to 58psi
This car hooks the air temp sensor to the fuel temp sensor for easier change out in case you want to go back for some reason.

Shoot me an email or call me Rob can give you my number.

Oh one more thing I was planning on implementing boost control on the stock ECU as well but i still need the help of MrFred for one scaling item. :)

Rock on :cool:

i wonder if you could run 2 map sensors those of you running big boost
with some sort of code to use the high resolution 2.5 or 3 bar for loads below 100 and then switch to the 5-6bar above?

interesting, I'm not too hung up on my scaling staying the same, I can adjust my timing/fuel maps as needed if it's off.

where are people getting the 5 bar kalvico sensor and cost?

can you elaborate on the iat sensor details?

I'm not interested in stock ecu controlled boost right now, maybe later.

my email is chris@mellontuning.com if you want to shoot that ROM over. another obstacle will be getting away from my beloved 96940011 ROM, I bet it's not supported.

Might be worth logging just to see what it's doing. It would show if it's a physical limit on airflow or an electrical limit. You may already be well past the electrical limit and just be tuning around it.

Here is one source:

http://www.zeitronix.com/order/order.htm#MAP50

I've seen the airflow data before on my car, it looks normal, just saying I haven't done it recently or continually.