Well...it's Tuesday....any results yet?

 

Well, it's late and I'm tired, but here's a preliminary rundown:

1) Fuel pump was restricting output to 49, causing leaning out and engaging knock/timing retardation at upper RPMs - pump output was manually adjusted/upped it to 57, helping considerably.

2) For some reason the PCM was referencing a low-octane timing table, knocking the timing down a few MORE degrees - this was reset - possible cause hypothesized by Magnuson: bad gas (???).

3) Highway mileage before blower install; ~16 mpg. Highway mileage since blower install; ~13 mpg. Mileage on the way back to San Diego from Ventura; 17.2 mpg.

Well, a few things were dragging down my truck, obviously the gas mileage increase is one clue. I have some other comments and questions, though, and will write more once I have had some sleep.

 

Here's my guess on what happened if the pump wasn't pumping out enough fuel.

The Truck was running out of fuel up top, starving the engine, making it knock. Once the PCM picks up a certain amount of knock it goes to the low octane tables until 20 gallons or 20% fuel is added, can't remember which, then it goes back to the high octane table until knock happens which occured quickly since you are running lean. Since moving to the low octane tables, pulling MORE timing, didn't fix the problem of being starved it was still picking up some knock and retarding the iming even more.

Glad to hear you got it straightened out.

FWIW ... My mileage in my Z got down to 9mpg with a combo tank and about 13-14 interstate driving. The headers were making it run pig *** rich since they weren't coated.

Good to see you improved mileage too.

 

More recent, detailed update on this?

 

yeah, what happened?

 

Okay, here's the deal.

Went up on Tuesday. Checked out the install, no problem there (the shop that did the install does Radix installs all the time). Went on a nice little drive with the Tech II installed (Magnuson has a convenient little drag strip outside that doubles part time as a commercial thoroughfare ). Heard a ping while at WOT in second, so we went back and had a look at the Tech II data. Looked decent - nothing to write home about, but nothing stuck out or was overtly out of whack.

Threw the truck up on the dyno and noticed that my curve shape resembled other blown 5.3L curves, but it was falling underneath the others. At about 4K RPMs, where the other blown 5.3L's continue upward (of course they have a robust database since most of the guys there have blown Chevys or GMCs), my truck leveled off and started moving downward. Something was up.

Hooked up a fuel pressure gauge and saw what looked like not enough fuel getting to the motor while at high RPMs. John had a look at the physical adjustment screw and said that it looked like someone had been on the regulator before - usually there is goop on the spline, but not on mine. It was reading 47 so he cranked it up to 57 (I think those were the numbers, though I'm not completely sure).

Ran on the dyno again but saw that timing was still getting pulled. Looked at the data and saw that the truck was operating on a low-octane timing table, and appeared to be stuck on it. I was asked about my gas (I only use Shell 91, the best available in California except for race gas), so everyone was perplexed as to how I ended up on the low table. Regardless, we called Superchips, uploaded a proper table, reset it, and ran again.

This time we were getting up to about 4800 RPMs before getting shut down. John hypothesized that the extra load the dyno presented was the factor, so we unhooked it from the dyno, hooked up the Tech II again, and had another run on the pavement. No ping, and air flow was 389 grams, up from the 366 grams I was seeing just after install. John says that in his experience there is nearly an 1:1 correspondence between grams of airflow and RWHP, so he said that I am definitely in the ball park for where I should be with a blown 5.3L.

About the Magnuson dyno...it's a Mustang dyno, but with 600lbs more load (or something like that) added to produce numbers comparable to Dynojet numbers. I guess the Mustang is 15%-20% more conservative that the Dynojet, and people hate the smaller numbers, so Magnuson modified and calibrated their Mustang dyno to produce Dynojet numbers. The day they did the dyno adjustment they ran a vehicle back and forth between their dyno and a Dynojet until the numbers were within 5 RWHP or so of each other. Most of the 5.3L vehicles there produce 380-420 RWHP on this recalibrated setup.

So am I happy? Well, I feel fortunate that Magnuson was willing to have a look at my setup and take some time to troubleshoot the issue. I really wish I would have had one more run on the dyno to see what was going on with the final tune I ended up with. If my truck was behaving badly with the extra dyno load, why didn't the other trucks that were dyno'd on it behave badly also? I though this was weird. I felt like we weren't done, but it was near the end of the day and they had worked about 6 hours on the truck, so I hit the road.

They told me that because my truck was completely stock except for the blower, I might be experiencing some restriction at the high end due to my stock exhaust. This week I had a Gibson 3" single pipe, side-swept cat-back installed. I was really trying to avoid this because I hate loud exhausts. I was told that the Gibson side-swept is the quietest out there, and that I would be able to hear it outside the truck, but not inside. This is not the case. I can hear it inside the truck and I am not happy about it. In retrospect, maybe I should have ordered the 6.0 H.O. Escalade EXT cat-back system, which probably wouldn't have been so restrictive, but also not as loud. Not sure what I'm going to do about this yet.

An interesting thing I did not get resolution on was my prior dyno results. We suspect that at minimum, the A/F sensor at the dyno shop I ran at before and after install is whacked out (I am not running at 10 A/F like those results say, I am running between 12.1 and 12.4, right where I am supposed to be). Regardless of the air/fuel stuff, even if the dyno was way out of calibration, the difference between the before and after install runs should have been 100-120 RWHP, since I ran on the same dyno 48 hours apart with nearly identical weather conditions. As you all know, the difference was 60 RWHP. What's up with that? It is still very much a mystery.

What now? Well, it is clear to me that I am not done. We ran out of time at Magnuson, but I think there is more to do with my truck. With a new tank of 91 octane and a more free-flowing exhaust, I think I need to have a look at things again. I am not convinced there is still not an issue, either with the blower, the install, or perhaps with my stock truck, since I have yet to see my vehicle pull steady up past 6K RPM's. It appears now that my job is to find a dyno shop here in town that can tune my vehicle on the dyno using the proper tools to monitor, measure, and adjust, and find a problem, if one exists.

If I have learned anything on this adventure thus far, it is the following:

1) The canned tune that comes with the Radix is a minimum tune, set to the lowest common denominator amongst the vehicles it was meant to encompass. Given this, staying with this 'stock' Radix tune will likely mean that you are leaving a lot on the table. Taking into account all the variables including your specific vehicle's characteristics, the blower's, your gas, where you live in the country, etc. etc., you can almost be guaranteed that there will be room for improvement (i.e. my mileage up to Magnuson was 13 mpg, on the way back home it was 17.4 mpg).

2) I will not be buying a tune by mail, ever. After my excursion I am convinced that there is no substitute for on-the-dyno tuning. There is just no way anyone could know what is happening with my vehicle and how it is behaving without seeing it behave, while it is behaving that way. Accordingly, there is no way to see what effects a change in programming has without seeing the effects a change in programming has. And the only way to do this is on the dyno.

In short, knowing what I know now, I see buying a blower as a two-step process: (1) Installing the blower, and (2) Tuning the vehicle after the blower has been installed. For those considering an install, this would be my recommendation.

 

Bottom line, there were some issues with your particular set up, but nothing that could not be worked through. I think that you have to admit that you were provided outstanding support by them, I don’t know of ANY other manufacture that would do what they did for you!


The tune that the Radix comes with is soft for a few reasons:

1) CARB legal (smog)
2) Can be daily driven
3) DEPENDABLE horsepower

I still think that MagnaCharger provides the most complete/dependable supercharger kit on the market HANDS DOWN.

If a customer wants to add boost, or tune the vehicle with LS1 Edit, then that should be left up to the customer.

BTW, Glad things are working out!

 

Thanks Fun Guy, I hope that you can get all of the quirks worked out, being you have so much time an money in this project, you should be happy. Good points about the stock radix tune, or any supercharger tune for that matter. You could take all of the trucks straight off of the line made this year and line them up and none of them would run the same, thus no tuner, no matter how good he/she is could tune perfect for each and every truck without knowing how the truck acts before and after. Keep us updated on what happens, Im sure you have a lot of peoples interest by now. Good luck man.

 

Magnuson certainly was not required to help me, but it was in their best interest to do so. You need to realize that if it they 'did me a favor', I also did them a favor. They had no blown Avalanches in their database, pretty much just RCSB and ECSB Silverados and Sierras. In the process of troubleshooting issues with the low octane table I was locked on, they discovered other, additional issues with the timing tables in general that were corrected by back-and-forth communications between John at Magnuson and the guys at Superchips in Florida. As a result of me putting the time, effort, and energy into getting my truck running properly, future owners of Magnuson's products will be better off, since my time in Ventura helped Magnuson hone their product (Radix + Superchips) better. I helped them out just as much or more than they helped me out, and if anything, future buyers will be the beneficiaries of this improved product.

 

Fun Guy...when you left Magnuson could you feel more power?

You said it well about "mail order tuning". Most of them are good guys but can not do it without seeing first hand what the truck needs. With superchargers or mods such as cams and headers LS1edit with a widebandO2 is a must. Anything less and you are just guessing.