Even after reading all this information and a lot of people obviously not big fans of SD, at least at the moment, I and still very interested it in and will hopefully be trying it out this winter. I am glad there have been a lot of big name shops/tuners put there .02 in this thread...I hope it keeps going...

 

Mrfred and GST, thanks for the input, good to see guys who are really deeply involved with the development of all the stock ECU stuff and that I respect chime in on this.

About the boost levels and fueling that you touched on MrFred. The AEM/Haltech/ViPec and many others use a boost fuel correct table so what you are mentioning doesn't happen. As boost rises the amount of fuel is calculated and added based on basically 100% more fuel being added per BAR of boost. Works really well until you get way out of the efficiency range of the turbo and then the car will start to get a little on the rich side if anything.

 

Or until your fuel pump can't keep up.

 

mrfred, I forgot where in the code the load calc is done with the SD code, but if it is the load+baro temp compensated load, then in your situation above, they should be identical maf and SD, with the reason being the temp is rising with the boost rising. Of course, depending on where the loads are calculated (I don't feel like reading the whole SD thread again )

Are you saying that the max load at boost spike didn't change or the load at redline? With a maxed out turbo I wouldn't expect the load at redline to change much, if at all, no matter what boost you were spiking to. The boost spike loads should change up until again you were well into the inefficiency range of the compressor map. But, if temp compensated load was used for map lookups, then all should be well, unless of course if the temp reaction is too slow, where the VE tables can take account for the inefficiency.

That sort of goes along with what David mentioned about SD and turbos out of their efficiency range though. That's where the VE table needs to be accurately mapped to account for that and if a VE table can't accurately account for it, then a separate correction is needed.

 

DB and R/T - Indeed with my friend's Evo, I 100% believe that the breathing capacity of the motor (perhaps not just the turbo) was maxed out, and this is why boost was going up while load was not changing. The challenge we have for SD is that we have no way to generate an accurate VE curve out in this VE range where many people are pushing their turbos.

 

Thank you everyone who posted in this thread! It definitely helped make up my mind, and hopefully it will help other people who are considering this route.

Dave, for the record it wasn't you who I spoke with, but another shop that I like very much. There are only 3 shops that I would trust to do any of my work - your shop being one of them but a bit far away, and none of them recommend SD on stock ecu so I am just going to stay with the MAF.

If English Racing was within 30 minutes from my house maybe I would try it out, but since I am going with a small stock frame turbo I don't think it's necessary for me to push that route now.

 

Its still not good for the car though. Nice that the car will still run smooth, but I think its bad to not know about it until later. If something goes wrong, I want to know about it right then and there. Not risk causing damages because the car still runs smooth.

 

Yeah, that is about what I expected.
FWIW, I'm on the quarter master, no-Bshafts, Comp 280 cams, head work, tubular exhaust manifold, blah blah blah. My car would stall constantly with even a 1200 RPM idle on the MAF. I definitely could have put more time in and fixed the issue and idled it at 1200 with the MAF. However, on SD, I idle the car at 800 RPM without a problem. Only time the car stalls is when I stall because the Quarter Master can make anybody look like an FNG.

I'll have to dig through my references, but I'm with Petey here. I had an SAE paper that showed like a ~2 pound/min gain (50 lb/min compressor) on a hot flow bench when they went from an open inlet to an inlet with flow straighteners. Pretty suprising. It's not a huge gain, but that's 20 HP on a car with a maxed out turbo.

 

Actual driving, you will notice an IC coupler popping off instantly. If the sound isn't a dead give away, the car pulling like a freight one second, then pulling like a stock 1990 civic the next, will be. No mistaking a popped coupler.

On the dyno, it's different.

 

its not any different on the dyno. if you pop a coupler off your pull will be WAAAAAY slower, car will sound different, and obviously the power will be down like 75%. if it happens mid pull, the torque will have a dramatic drop off.

 

I Did speak with dave about this and i am glad that he turned me down i like that if the tuner is not 100% happy with it he will not tune it he stressed that he wanted somebody local that way if there was any touch up needed or problems he would be right there

 

we see between -30 and -40 degrees here in wyoming

 

I think it may have been more the turbo being the limiting factor rather than the engine itself. Keeping temperature a constant, the more pressure you add, the more airflow through an engine you will get. Out stock turbos can only flow about 42-43 lb/min max, and that's only about 22ish psi at redline, depending on mods. But the engine itself can flow much, much more, only limited by the pressure and temps that the turbo give it, ie...cars making 1000whp shows that the engine itself isn't the limiting factor.

Volumetric airflow through and engine can be calculated as:

Airflow (CFM) = PR[RPM*V.E.*Cid/3456]
PR - pressure ratio (boost)

The mass airflow is then temp corrected from that. That only leaves VE and temperature as variables in the ultimate mass airflow and power. It would be interesting to see actual VE measurements of an engine at different boost levels, but I don't think it varies enough as compared to the contribution of the boost and charged air temp. The way I always look as that equation is to figure the VE of the engine in an NA state, simply shaped by the RPM curve...the VE of an engine is going to have a natural curve to it. When we add a turbo to the mix, we simply calculate the mass airflow from the temp and boost pressure. The temp we can measure directly with out IAT sensors, but can also be calculated simply by looking at the compressor maps for the turbo.

In terms of the SD patch, you can still account for this in the VE tables. In your example, if you are turning up the boost and your mass airflow isn't going up (baro+temp comp load), then it has to be because the temp is going up (inefficient turbo). So, in terms of tuning SD, simply make the VE lower at that same RPM for the higher boost so that the mass airflow calc comes out to be the same. But again, I defer to how the actual patch is coded up. I forgot more and more every day

But, I'm interested in what you saw when you were tuning that particular car. What boost/rpm and boost+addition/RPM gave the same baro+temp comp loads? On my stock turbo, all the way up to 32 psi I would get increasing loads. Of course at redline, probably from midrange to redline, where the turbo was basically riding it's choke line, the loads were the same. But, that would be expected on the stock turbo. Is that what you were referring to or am I just misunderstanding something?

 

for someone like myself:

Live on an island elevation fluctuates from 0-1500 ft above sea level, 25* temperature fluctuation at most; I think SD is a fairly reasonable option. Then again not everyone lives in Hawaii. I would think that any state with the relatively same atmosphere have less to lose compared to someone who lives in lets say: Colorado.

 

I meant to type It "must be different" , as I have absolutely no experience with, nor have I ever seen a dynamometer in person.