t_raven

iTrader: (12)

Posted this in the dyno section but shoulda realized this would be the better section.

I've been reading Greg Banish's books to get a handle on things before I start playing with my hptuners. I obviously won't be tuning on a dyno but I'm curious now about different strategies to tune on the two.dumI understand the benefit of steady state testing with an eddy current dyno, especially for VE modeling and spark hook tests. Greg's books are written for steady state tuning, and I saw no real mention of tuning on an inertia dyno. It's good info but it seems like most shops have inertia dynos. Street tuning would be more like tuning on an inertia dyno, so knowing the tuning strategies on an inertia dyno would be helpful for street tuning.

Is it really that beneficial to use an EC dyno, or is this one of the cases where practical application can overcome theory? Can a good tuner produce just as good of a tune on either?

Without being able to hold steady in one cell of a VE map, how do you map VE on an inertia dyno?

Without being able to do a spark hook test, how would you find MBT at a specific rpm?

bayer-z28

iTrader: (14)

You *can* tune on the streets. I do (don't have the $$$ to rent a dyno). I know it's not the most desired or respected, but a lot of people do it and you do get a real world load of the vehicle. EC replicates the weight of the vehicle on the street and the normal resistance that comes with it. A free wheel dyno is just that. No specific load and just drums with a couple sensors.

If I need to populate a table of low vacuum at a lower RPM, I just ride the brakes until I get it into that kPa cell. I can tune a whole RPM range of vacuum like that. Some people gave me looks when I was screaming on the HW doing 60 in 3rd gear riding the brakes....

I try to keep transients as smooth as possible. Only time a snap the throttle is when I'm doing a WOT pull. And the VE table tuning has a times table also, so I can see how many times that cell has been hit. If it hasn't been hit many times, I don't correct it. Like Greg says, I try to get as many hits as possible. Helps to have a competent buddy in the pass seat to tell you higher or lower. I obviously don't do it for a long time, just enough to sit at a couple cells and then let off.

I was schooled by Greg as well, so I know the side effects of street tuning. I was actually planning on renting a dyno some time to set timing. I adjust the timing a little bit, but I never push it far enough to hit knock. I stay under 38* in higher R's, as a general rule of thumb. My lower RPM Low vacuum tables are under 30*.

But yes, an EC Dyno is THE BEST tool for tuning because of the various features that Greg points out. You can't really do steady state with a free wheel dyno. (IIRC) The Dynojet 224x Has EC, I believe. 224 does not.

turbolx

For WOT testing, the biggest difference is sweep rates. If you look at how long it takes to complete your average pull (3k-6.5k RPM), you'll see a significant difference between the two dyno types. Inertial dynos tend to allow the engine to sweep faster, especially if the engine makes a lot of power. By comparison, a loaded dyno is able to replicate the same resistance as the vehicle would see on the street. Done properly, an eddy current dyno sweeps at exactly the same rate as a vehicle driving down a road/track.

Recognizing this, some tuners just "leave some safety margin" when tuning WOT fuel or spark. While having a safety margin is a good idea, it's even better to know how much you've left. If you're guessing, well...


In short, you don't and you don't.

VE mapping requires steady state conditions to avoid confusing wall film (transient fueling) with the base fuel number that should be exclusive to steady state. I see a lot of errors where people end up baking in transient errors to the VE surface because they refused to test in steady state. Later on, when you want to "fix driveability" it leaves you with a bigger mess.

See my note above about WOT spark. At part throttle, you're completely blind on an inertial dyno when it comes to finding MBT. Since by definition any force causes an acceleration on an inertial dyno, finding the point with the most force (torque) at a specific airflow (load) and rpm requires that you hold something still, which isn't possible on the inertial only dyno.

I know lots of places don't have load bear dynos. Many of these even have good reputations with throngs of fans who wouldn't think of bringing their car elsewhere. That's great, but it still doesn't change the science of the ECU was designed to work by the OEM. I find it much easier (and more consistent) to just work with the science instead of against it. Step one is understanding the underlying theory.

t_raven

iTrader: (12)

These are some of the concerns I've had about shops with inertia dynos. That's why I was curious if there are strategies to achieve the same results. Not wanting to pay someone for a less than ideal tune was one reason I decided to do it myself.

t_raven

iTrader: (12)

I've figured most VE cells could be hit on the street with different speeds in different gears, using hills, or even the brakes like you mentioned. I figured I could throw some old pads and rotors on just for that and not have to worry about warping them lol

ctd

iTrader: (1)

Looks like you live around a few hills. Use your cruise control for steady state, different gears to move the RPM columns. Example, find a rolling hill area, set cruise @ 50 mph in fourth gear, then make the same run in sixth. Different gears @ different speeds steady state. Make sure the cell count number is high enough to give good data.

For WOT I have a few quiet roads with nice up hill grades, I start with 3 gear run from 2 - 6.5k rpm. The first few runs you may to abort however you get the trend of what is needed to build the tables.

Myself I prefer to do the MAF table first, much easier. You don't have the multitude of cells to populate. If you are a math wiz you build your start up VE table from your solid MAF table or the other way.......I'm not a math wiz.

Use your scanner just like a dyno, dynamic cylinder air & dynamic air, torque & HP lines. You can immediately tell if you are improving or not.

I tune both on the street & on a loaded Mustang Dyno. Both way's are very good, I've melted a lot of **** on the dyno building VE tables.....holy you build some heat!

turbolx

One of the problems with "hitting every cell" on the street is that you tend to sweep through a lot of the critical cells during normal acceleration. This sweeping data pollutes the steady state data and can have you "baking in" some transient fuel compensation to the VE table very easily. If you watch my DVD, you'll see that I don't even begin recording until I have reached steady state on the dyno to avoid this.

Yes, it's possible to use a combination of road grade, brakes, gear selection, and throttle to get into some of the cells that would be simple to find on a load bearing dyno. Just like it's easy to overheat things that depend on airflow for cooling on the dyno, you can also overheat things on the road by dialing in "abnormal" conditions as well. Be careful!

t_raven

iTrader: (12)

The man himself graces my thread lol . Your books helped a lot. I've got hptuners for my LS stuff but I've also got Gen 7 DFI I'll be putting on the 455 in my 67. I feel like I've got a good general knowledge from your books, I just need to get familiar with those two software.

Thanks for all the input guys. Luckily I live in an area with a lot of very empty roads and various hills. Got a lot of reading to do still. I'm gonna tune my 01 TA in stock form to get the hang of it before I start installing parts

Slowhawk

iTrader: (12)

Load dyno just makes it alot easier, expecially high powered/barely legal street cars. I would not trust a non-loaded dyno for any part throttle tuning.

For basic stock, cammed and even H/C cars you can do the tuning on the street fairly easy.