Dynoed my Truck Today

GMC_DUDE · May 6, 2004

In preparation for the s/c install, I took the truck up to Bellingham and had a baseline dyno test run. The results were very consistent across the 3 runs, averaging 240 max. rwhp, and 250 max. rwtq. Not too bad for a 4.8 with auto and 4WD drivetrain . Once the s/c arrives and is installed, will run another test and, if anyone is interested, will try to figure out how to post images of the test results.

Peace and cool-ness,

GMC_DUDE

May 6, 2004

GMC DUDE,

Nice #'s. Is your truck stock? Can you give us some more info about your truck?

Thanx in advance.

03Bowtie · May 6, 2004

I'd also like to know what you have done to your truck already. I've got a '03 4.8L ext. cab with a dynomax muffler and custom tubing and a AEM Brute Force intake. Mine dyno'd at 220 RWHP (got 2 good runs at 220). If your truck is stock, then your dyno guy didn't calibrate something right. There's no way a stock truck w/ the 4.8 is making 240 at the rear wheels. Heck, it only makes 265 at the flywheel.....

GMC_DUDE · May 7, 2004

Yes, the truck is modded. The performance mods are: K&N air filter, JBA shorty headers, Flowmaster 70 single in/dual out exhaust, and Flex-lite (sp?) 290 electric fans. I got the numbers from examining the curves themselves, and from the tuner's printout, to make sure I wasn't reading an A/T shift spike (the max. numbers the dyno software prints on the graphs often did this). The 3 runs were within a couple hp/ft-lb of each other, so I believe the results are accurate, at least for that dyno in that location. I would be careful, though, about comparing these numbers with those from other dyno's, as there is no way of knowing if either of them are properly calibrated (BTW these are raw numbers, not SAE corrected, and from a Dynojet dyno). It does seem strange, though, that I am making 33 more HP than Durkin's Tahoe did pre s/c'ed, since he and I at that time had essentially the same mods and drivetrain, and he has the 5.3 engine.

GMC_DUDE

Durkin · May 8, 2004

GMC_Dude:

Those are great numbers!

Since your HP is higher than mine ad your torque numbers are lower, one explanation is that you may have pushed it way past where my dyno operator quit (since we never got past 3,950 RPM) and I think peak HP occurs around 5,200 RPM. As you know torque drops as rpm passes a certain speed and I think that on these engines it ia 3,200 on a stocker.

Baseline stock dyno results run by AAA Muffler Auto Performance in Costa Mesa, CA at 90 MPH were: Rear Wheel Horsepower = 207; Torque = 277 ft lbs; RPM = 3,950; the speed limiter was on, but we did not hit it.

The fans might be worth 10 to 15 HP assuming the stock fan was removed and I am sure you would not have both.

Hope tou kept your fan shroud though because you are probably going to need it; thats what yer Radix intercooler reservoir and pump are supposed to mount on. If not, Ii wil be interest in where you mount it, because I want to replace mine and add a Mezziere electric pump!

Anywhich, keep us informed of your prgress and good luck.

Regards,

Durkin

GMC_DUDE · May 8, 2004

Well, there's the first installation hitch, and I don't even have the unit yet I do have the shroud, but there is no way it will fit over those humongous fans, and the e-fans are too nice to go back to stock. Oh, well, there will surely be more glitches, but I don't have two engineering degrees for nothing, so I'm sure to figure out some solution.

Anyway, on the dyno you are right, they did a 1,2,3 run in tow/haul mode, and the data is from second gear (with corrections for the gearing of course). On third gear we banged into the 100 MPH vehicle speed limit at about 4300 rpm , but the Radix tune should take care of that . Looking at Run No. 1 data, the peak torque was 251.6 at 4600 rpm, and peak hp was 241.0 at 5200 rpm. At 3900 rpm the engine put out 185.5 hp and 249.8 torque (love that flat torque curve ). Anyways, it will be interesting to see what the s/c does to the numbers.

Peace and Cool-ness

GMC_DUDE

Durkin · May 8, 2004

GMC_Dude:

If I can be of assistance; let me know!

Keep the fans and find an alternative! That is what hot rodding is all about!

You do not need two engineering degees to find a place for the Radix stuff, but it may help!!

Think you onlly need the far upper left 1/4 part of the shroud any way; if you wish, I will take a pic of where the stuff mounts!

Patience will be good!

Regards,

Durkin

GMC_DUDE · May 8, 2004

Heck, it wouldn't be any fun if it all just bolted right in! Where's the customization in that?

(edit)

But I do have a question. I was reading through the installation manual which I downloaded from their web site (why doesn't that other company let you do this?) and I noticed that the serpentine belt is replaced with a different (longer?) one. However, the belt is not listed in the parts list and they supply a part number for it at the beginning of the instructions. Is this something I have to buy separately? If so, who carries them? Is there anything else major (besides the tools they list) that I would need to buy?

(/edit)

Anyway, I guess that's what scares me a bit about the Radix kit, is that I am sure there are going to be places where things don't go together as they should. Hopefully, they will be minor things, easily solved, and at any rate, I've talked to the Magnacharger support people and they are really great One of the reasons I chose Magnacharger.

Peace and Cool-ness,

GMC_DUDE

Durkin · May 8, 2004

GMC_Dude:

The belt is in the kit.

Every thing fits perfectly; no need to improvise anywhere. All you need to provide is the truck, a few tools and about 9 to 12 hours of wrench time.

do not forget to drive yer truck till it is is empty and fill it with the highest octane you can buy--before you start the install. After its in, you are through using the cheap stuff.

Regards,

Durkin

03Bowtie · May 10, 2004

GMC_DUDE, when you did your dyno runs, did you actually shift gears during the runs? On mine, we just did 2nd gear roll-on runs till it hit the rev-limiter. It was really weird when it hit the limiter. I was expecting it to pop and cut in and out intermittently, but it just kind of cut out all-together almost like he let off the gas.

GMC_DUDE · May 11, 2004

Well it's here!!! Was on my porch when I got home from work today. (Thank heavens I live in a good neighborhood ). I've been looking the kit over (will take official inventory later) and can report the following so far:

1: Yes it does come with a serpentine belt, so my fears there were unfounded.

2: Mounting the intercooler shouldn't be a big problem with the e-fans. I can't put it in the normal spot, but it looks as though I can mount it to the fuse/relay box with a home-made bracket of some sort.

3: The biggest challenge will be dropping in the s/c itself. That thing weighs a TON!!! (well, OK, 85 lbs. according to the package). It is far more than I can lift. A friend offered to help, but I don't think even he and I can do it, especially leaning over the engine bay. I think I will be looking into renting/borrowing some kind of engine lift type device to hoist it into place.

Otherwise, I've been reading the downloaded instructions over and over, and it looks like the installation is pretty easy, just a lot of little steps. I spent (literally ) last weekend buying the tools I will need but didn't have. Will keep everyone posted.

03Bowtie,

On my dyno runs they put the tranny into "3" and also into tow/haul mode and ran it through the gears. Mine did not hit the rev limiter, although I have hit it once (OK, OK twice ) on the street. We did hit the 100 MPH speed limiter though, and so had to throw out the third gear results. I don't think using the "2" position on mine would work very well, because although it starts and stays in second gear on light throttle, pushing it to the floor will cause the tranny to downshift to first (never had a vehicle that did that before). When I figure out how to get cardomain to host my pics I will post the graphs of the runs.

Peace and cool-ness,

GMC_DUDE

P.S. Just discovered an annoying trait of this board. If you edit your post a second time, you lose all your first-time edits.

Durkin · May 11, 2004

GMC_Dude:

Still wonder where you are going to mount the reservoir and pump for the intercooler if the shroud is off?

Regards,

Durkin

Durkin · May 14, 2004

GMC_Dude:

Looks like tomorrow is the big day!

Good Luck!!!

Regards,

Durkin

GMC_DUDE · May 15, 2004

Actually I've been at it a couple days now, doing a little bit after work. Hopefully it will be wrapped up this weekend. So far things haven't been too bad, although the occasional little gotcha's have occurred, like GM omitting the drain valve on the radiator (see details in Bash/Rant section). The parts inventory freaked me out for a bit until I realized 1) They had pre-assembled a few things, so the itemized parts which appeared to have been shorted were actually on an assembly. 2) They went with a completely different intercooler than the one shown in the downloaded instructions , but fortunately the printed manual is up to date and shows how to install it.

Speaking of which, in my earlier post I should have said I was going to mount the intercooler RESERVOIR and PUMP on the fuse/relay module, since it won't mount on my e-fans, not the intercooler itself.

Solved the s/c weight problem by buying a "cherry picker" hoist to lift the thing in. Just tried it out this evening and I think it will work great.

The remaining tasks now are:

1: Finish the installation

2: Pay everything off