Quote:
Originally posted by EddieSVX
I wish I still had the URL, but I saw a dyno chart of a stock SVX once and there wasn't that big HP/torque dip they show between 2700 ~ 4000 RPM or wherever it is in the range that they claimed it dips a lot and that the replacement chip fixes.
So I dunno, I think this may improve a little but not as much as they advertise. Maybe they let go of the gas momentarily or weren't hard pressing it during those RPMs, or maybe their specific car had issues.
The HP/tq curve of the stock SVX I saw was pretty linear.
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Here's a plot of chiketkd's car on an awd dynojet (dynojets typically show higher #'s than dyanpacks). This is a plot of a very healthy svx with better than typicall driveline efficiency thanks to a transmission transplant. You'll notice that it comes out of the 2500 rpm stall at around 80hp. All of our runs on the factory software were about the same be them good runs or bad runs. Now we did have good runs and bad runs and the plot shown in our hp comparison is a bad run. Chike's plot would be indicative of a good run. Here let's look at it:
Ok, now we chose to use a bad run in our comparison. We chose this bad run not to be deceptive but to illustrate the problem with the factory tuning. The bad run is a valid indicator of real life performance because it happens in real life pretty frequently with the factory software on the us market svx. Mass air meters are great. Personally I think it's THE way to go for engine management but at the same time they like any technology do have limitations. They are slow to register the rush of air that comes in when the throttle is opened far and fast. In order to overcome this limitation there is a seperate fuel enrichment based on the throttle position sensor to stop the car from going too lean when the accelerator is floored. It uses a table to look up and add a set # of milliseconds of fuel injector pulse width according to the tps voltage. The #'s in this table are ballpark #'s since they are based on throttle position and not actual air mesaurements so in some conditions they result in the afr being a little richer than was planned and in other conditions a little leaner. Because the SVX is already nastily lean from the factory when the throttle enrichment isn't enough and the afr goes even leaner the power loss jumps from bad to terrible. I drive an SVX myself so I know about this intermittant lag all too well and I'm sure you do too. We shouldn't just pretend like there aren't times when we press the gas and the car just kind of sits there for a second before it does anything. It's an annoying problem which the stage 1 software does fix. So now let's look at the plot provided on our website:
You should note where the plot with the stage 1 software comes out of the torque converters 2500 rpm stall. You'll never find a stock svx doing that and that's no one time thing; every stage 1 plot shows the same low end increase. Whether you are comparing to the best stock svx plot you can find or the worst you will still see that a stage 1 starts at something like 112 ( i can't remember the # off the top of my head) and stock svx's start off around 80hp.
I imagine you can appreciate the plot comparisons better now so I'll move on to touting stage1v4. The plot on our website is not of stage 1v4. It's of the original stage 1 software. Someday we'll go do some more runs and we'll post more plots. Maybe next time I show both a good and bad run on factory software so the skeptic inside doesn't get the better of anyone who would otherwise be thrilled to say goodbye to the lag in their svx. Now while we don't have any plots of v4 everyone seems pretty thrilled with it. I think it's safe to say there's a good improvement over what i think was a pretty impressive improvement with the original stage one software. We've also made some nice drivability improvements. Try to drive someone elses SVX who has it if you can.