SPANKY LS1

iTrader: (24)

At what point is BS3/DFI necessary? Previously, wasn't the primary limiting factor of retaining the stock PCM the fact that the MAF couldn't keep up with the demands of a high RPM/HP motor? IIRC, the stock PCM is good to ~8,000, so hyphotecially couldn't a <8000rpm N/A or NOS 346/408/422 be able to be sufficienly tuned via HP Tuners (SD mode) as opposed to needing BS3/DFI? Basically, what can BS3/DFI do that the stock PCM can't do in SD mode, what are the limits of te stock PCM?

Thanks, Shawn

cyphur

iTrader: (10)

isn't it easier to tune w/BS3 and such things like that, than trying to manipulate the stock PCM?

SPANKY LS1

iTrader: (24)

Ok, let me try it this way:

What is the limit of the stock PCM when being tuned in SD mode?

sb427f-car

Computing speed is one thing. The aftermarket PCMs have better hardwear in them to process more data, faster and thus better control the engine. The fact that you can use the PCM to drive other accesories (nitrous stages via an integral window switch) a built in boost control to run in hold, step, or progressive for a turbo application, built in 2 step, ect, ect, ect. You do get what you pay for, but for 75% of the people on this board (maybe 85 or 90%) we'll never use all that's incorporated.

HumpinSS

iTrader: (1)

Magnus posted before the stock pcm has a faster processing chip in it. Faster than the aftermarket ECU's

MUSTANGEATER

iTrader: (10)

The big thing I would look at since you mentioned Nitrous is the capability of the system to retard timing or control multiple stages of nitrous. The ease of tuning with BS3 as opposed to a Mass Air or Speed Density setup would also be a good reason to pick it up. The BS3's data log ability is the **** too.

If you can or know someone who can tune the car really well in speed density I wouldn't hesitate doing that but if you don't might as well splurge for the BS3.

Pro Stock John

iTrader: (34)

BS3 is good for max effort forced induction. Could be good for high rpm big inch motor.

Judson for example runs a FAST with an MSD crank trigger.

Magnus

iTrader: (4)

All depends on what you are looking for

Nitrous controller is one reason to use an aftermarket unit.
Closed loop wide band correction at WOT is another good reason to use an aftermarket unit.
Support for low impedence injectors is another.
Integrated boost control would be nice as well.
Real time tuning too.

That's pretty much all I can think of that aftermarket units have over the stock PCM. There are probably more but I can't recall any off hand.

Factory computers have more paramters to adjust operating conditions as well as better resolution on fueling tables (from what I have seen).

Now that our 2bar product has been out for quite some time, there are quite a few cars that put down over 800hp to the wheels with it. It makes tuning boosted cars a lot easier using the stock PCM.

But, the stock PCM cannot do the things I listed initially which are the main reasons people switch to an aftermarket unit. In just about every other catagory the stock PCM wins, imho.

- Keith, HP Tuners

kp

iTrader: (34)

The DFI has so much cool stuff, the stuff magnus mentioned plus switchable dual spark maps, individual injector tuning, add fuel for the nitrous (no worry about solenoids failing), n2o timing retard, 3 stage nitrous control that shuts off at a predetermined wideband point for safety, two step, shift light output, fan controls, write the VE table as you go, easy/quick logging etc - very tweakable. After a little time playing with the cold start stuff I could reach in the car, turn the key and fire the car dead cold on a 45 degree day with a 276 degree @ .050 cam and it fired right up and idled - try that with a dominator carb

I'm sure the BS3 and FAST has similar options, never seen the software for BS3 but people seem to like it for LS1s.

But, since some of the gauges on these cars plus the speedo is controlled by the ECM I would honestly stay with the stock computer unless you were doing a big FI or 8000+rpm nitrous setup or a race car only setup where you pull all the wiring. People have been having excellent results with the HPT 2 bar and if you spend a little time with it a SD tune on a n/a car is fairly easy once you realize whats going on. Plus buying a tuning package is a lot easier then rewiring your whole car, out of all things DIY people are scared of most its usually wiring. If I was doing an all out n/a race car I would have an aftermarket ECU in there just for the extra race car features that you would have to add on using the stock setup - less wires the better and I would rather control everything at one central point.