PDA

View Full Version : End game numbers from my 98 K2500



greatwhite
05-29-2012, 16:58
Submitted for your perusal, the chart below represents where my truck is currently at:

http://i1174.photobucket.com/albums/r618/justonepict/photo.jpg

That chart is consistent to within 5-10% variance on subsequent runs.

I don't have access to a dyno, the nearest one is a 6 hour/$500 ferry ride and another 6-7 hours driving on either side of that. 20 hours just to get there and at least 800-900 bucks. Thats just not practical/affordable/reasonable so I use an iPhone app instead.

That chart comes from an iPhone app that's comparable (reported to be) to a Gtech pro in accuracy and uses the accelerometers/GPS data in the iPhone itself.

Stats:

Weight - 6900 lbs. Actual weight on the scales, not a guess - scaled with full tank and driver, have about another 100lbs in it with 3/4 plywood bed inserts, lots of my stuff and a fiberglass truck cap. Yup, she's a bit heavy all kitted out for daily use....

Drivetrain loss - 15% (best guess)

Performance:

0-60mph - 9.57 secs

Crankshaft HP calculated estimate from the program- 300hp. So lessee, Guesstimate about 260 or so at the wheels?

Showing 17.30 second 1/4's at 88.2 mph. *Yawn*

Abysmal 60 foot times of 3.50 secs, but on BFG AT tires at 60 PSI for towing. Lots of spin, lots of pedaling out of the hole. You can see it at the beginning of the graph where it's near the zero mark for the first second of acceleration as I fight it for traction.

It's a good 5-10 feet before I can pedal it enough to hook from a standing start the program requires. A better launch with less wheel spin and a bit of boost would make for maybe a half second lower 0-60 number and perhaps a bit more calculated HP. Problem is, any boost at all before launching just sends both rear tires (g80) completely up in smoke until you lift right out of the throttle. Ya just gotta stab it from a standing start an bog it or pedal it or your run in useless.

The truck:

1998 K2500 with just a fresh GM8, TM, diamond eye exhaust, my GMparts replacement Optimizer 6500 (about 15,000 kms), 4L80E, 4:10, Stock tires and suspension height, stock DS4 and my personal brew PCM calibration ( I have Tunercat II and the ability to tune/flash my own PCM).

No water injection (I have devils own progressive WI installed but it wasn't turned on), no intercoolers, no nitrous, no propane, no power adders of any sort.

Just a straight section of flat highway, dry pavement and an operating temp engine.

EGT's topped out at 1120 (I have digital gauges), foot hard to the floor, and won't go any higher.

Still hauls my 35 foot 8500LB TT with ease and EGT's hover around 750-900F depending on the grade. Will haul 4th of July, vantage highway, Lookout pass, etc at 55mph with 1050 and Water temps around 210.

It also a daily driver with TDCO set at a very rattle friendly .25 (much more advance gets the missus complaining about the noise).

Around 15-17 in around town, can get a couple more in all highway driving.

Pretty much the end for the truck as it sits as I don't think the current combination has much more than another 5-20 hp left to squeeze out of it at best and that would start making compromises in day to day use.

I have future plans, but that's a bit "hush hush" right now....lots of fab required to keep it usable day to day and get better numbers.

I'm actually pretty happy with it as is for what it is.

It motors away from traffic whenever I want. The throttle is morelike a like a potentiometer than a throttle, want more speed just dial it up and she goes. No muss, no fuss.

I've surprised a couple guys that have tried to keep up and had a couple Duramax owners (mostly stock trucks) in the passenger seat give me strange looks when I stomp the loud pedal and they get shoved into the seat. The torque curve is pretty flat and it will yank my trailer across country with no more prep than filling the tank.

I'm in to the truck for about 17,00-18,000 now, including the original purchase price, new Optimizer and all the various bits and bobs (heck, Tunercat II took almost a $1000 bite out of me alone). Honestly, I kind of lost track of the current cost after the 599 cracked a piston and I had to pay $10,000 to have the new optimizer installed. I was on a trip and had no choice but to pay someone to do the work. $7100 for the engine and another 2500-ish in parts and labor.

I know it sounds pretty unrealistic in the claims department compared to a lot of other 6.5 trucks out there, but the mileage is calculated across a couple months, the performance is right off the program and not my "guess" or impression of the truck and the drivetrain is essentially brand spanking new.

I was also stuck at the 200-220hp mark for a long time before I broke through.

So it is possible to get decent number out of the old hacks, but it ain't cheap and it ain't easy.

YMMV........:cool:

lilymonster
06-01-2012, 07:13
I thinik this is pretty darn good. This is a simple old school diesel engine with the basic fundamentals of the engine having been designed by GM/Detroit in the NINETEEN SEVENTIES. Yes, the late 1970's when the new 6.2 was their most foward, advanced concept . Of course you all know this, but sometimes it is worthwhile to remind yourself/others. Considering the near 30+year old design of the motor and heavy weight of the vehicle, and the excellent everyday reliability and usability that were retained, this is great performance. Also keep in mind, we all run big tires on these trucks, the older drivetrains are pretty inefficient, and the GMT400 body style has aerodynamics on par with a cardboard box. Now, all of these statements are exactly why I LOVE these trucks. I just love the simplicity, low price, and all around good design of these vehicles. To me, its a fun and rewarding truck to own and drive. I own a shop and a used car dealer and people always ask me, "Why do you drive that old thing? You should Just go to the auction and get the latest, greatest, Duramax LLXYZ and put it on your floor plan." And the answer is, I've been there and done that. I've owned and driven all sorts of Duramax trucks over the last 10 years. I'm over it. For me, these older 6.5's are much more rewarding to own due to the simple, fun, hassle free, low cost ownership experience. Plus I'm not a flashy guy at all and I don't like the idea of driving around a $50k+ PICK UP TRUCK. Anyway, sorry about the tangent, I just thought I'd say what was on my mind, Hope you found relevant.