Repair-It

Bob wrote:Yeah, I think the 2500 is going to be a bit rough as a daily driver. I would be in favor of the half ton for anything but heavy towing.

I think the thought was Ranger replacement and Caprice backup.

As far as I can tell, there was a light duty 2500 from 99 to 2000. According to some research, it would be only 150 lbs lighter similarly equipped. A small amount of that weight reduction is lost because these are the only two years for iron head engines.

I wish they were more common, since I still think it would be the perfect fit. Not because of the lighter weight, but better ride and lower bed/body height. Since they appear to be HD only from 2001 and up, I don't think it is worth trying to track down one from a 2 year run.

I did also determine that 4WD costs about 300 lbs and the extended cab costs 400 lbs. I like the extended cab from the perspective of being able to put kids back there when using the truck but now it is up to a 5,8xx lb vehicle with the 4WD...

Plus the chances of finding one in my price range that is not totally rusty is going to be much harder, anyway.

Some auto trader comps. It puts the Craigslist one right where it should be in terms of price and condition.

http://www.autotrader.com/cars-for-sale ... 4508&Log=0


http://www.autotrader.com/cars-for-sale ... 3353&Log=0


http://www.autotrader.com/cars-for-sale ... 1507&Log=0


http://www.autotrader.com/cars-for-sale ... 2733&Log=0

https://youtu.be/CqllpMpEdjM

https://youtu.be/uXrwRohOfjg

https://youtu.be/8ZrrSG8FF5U

https://youtu.be/Lr2cLtHsXwg

Helping?

Adam wrote:https://youtu.be/CqllpMpEdjM

Saw that. But it does inspire getting something and then getting almost 40 extra rwhp out of it. Really need a dyno and WB though...

https://youtu.be/uXrwRohOfjg

Saw this. It was the inspiration for this whole 2500 thing. Except I have sort of convinced myself that i want 4WD...but if i found a clean 2WD for the right price, I would still look at it.

https://youtu.be/8ZrrSG8FF5U

Don't think i saw that. I think that was his original truck and i also think it was a 2000 light duty 2500. Look at the black spacer between the front bumper and bottom of the front fender/headlights. It is 2" taller on the previous video than here, because the body is higher. That is one way to tell the light duty 2500 from the HD.

https://youtu.be/Lr2cLtHsXwg

What's making it so jagged did you find out?

Stock tune in these trucks commands 14.7 all the time

Oy.

14.7 what?

billgiacheri wrote:14.7 what?

Air:fuel ratio. 14.7 is stoichiometric, which is usually maintained in closed loop by the O2 sensor during normal operation (idle, part throttle). He's saying that this truck basically never goes into PE. PE is power enrichment which is an open loop mode that engages near WOT. Extra fuel is injected (usually quite a bit) which aids in cooling the cylinder temps. Most OEM tunes have a ton of PE fuel and you back out a little of this fuel to gain some power at WOT. In this case, 14.7 is actually too lean for ideal power and it wants to be richened up. I think this phenomenon is due to the 5-speed manual calibration. I wouldn't be surprised if there was a timer to delay PE fuel. I know GM did this as far back as late 80s TBI truck calibrations.

He was saying he's seen every instance of spark and fuel combination on OEM vehicles. The combinations are:
1) Not enough spark and too much fuel (like the 2015 Silverado video Adam linked). It took a ton of extra spark and in concert with less fuel, made another 40 rwhp.
2) Not enough spark and not enough fuel
3) Too much spark and not enough fuel (I hope this isn't intended by the factory)
4) Too much spark and too much fuel (I think this is less common but does happen - back in the day neanderthals of carb tuning thought this made the most power)

I want to say that #1 is the most common and is quite conservative. That 5.3 had like 13 degrees of spark at WOT he was saying and was quite rich. For reference, Sloppy commonly runs 13 degrees of total spark at WOT under BOOST (granted this is the new DI 5.3). That thing would probably last like half a million miles at WOT like that. Crazy conservative.

I should note that factory conservatism isn't necessarily in place because any changes will necessarily harm the engine. It is more that there is substantial safety margin in case things change over time. Sensors get dirty and inaccurate, fuel injectors get clogged, radiators can become inefficient, and there is no wide band information available to tell what is happening. But if you have the instrumentation, you can safety take away this safety margin - you just need to be continuously more aware of engine parameters, which most people obviously are not interested in.

Adam wrote:https://youtu.be/PCf9KD_tpgY

So he said the truck was like 5,1xx with him in it. A 4WD 2500HD with me in it would be pushing 5,700 lbs so add 600 for the purposes of this conversation.

He ran a best of 11.964 @ 121 mph. That was with a very lethargic 60' of 2.141 which is what my Caprice is capable of to put that in perspective. So, what happens if we added 600 lbs but also added 4WD?

A drag racing calculator says his combo is putting out 740 hp at the crank. The same calculator says the trap speed would drop to 116.6 mph with the added weight. But with a strong launch, the ET could be as low as 11.5. Now the question is, what is his exact engine setup and what would I realistically expect to accomplish?

If we back that off to 625 crank (call it 500 rwhp), the estimate says 12.2 @ 110. That is fast but also only 5 mph faster in trap than my CTS-V, with worse aerodynamics. For absolute performance, it's not really any faster than a brand new Chevy SS with drag radials. But it would still be faster than the CTS-V, and one hell of a sleeper. That said, I like the 120 mph trap speed number a hell of a lot more.

Here's a bogey for you: C5 Z06. If I can't at least walk a 2002 Z06, that's not enough. Gonna need a very low 12 ET to get one on the launch and something close to 120 to walk one from a roll.

So I really need less weight, OR a reliable path to more than 500 rwhp.

If I raise the power to 600 rwhp, which is about 750 crank, the ET falls to 11.5 and the trap at 117. That is more like it.

Fortunately I know 600 rwhp is quite possible and may even be feasible on the small rod LQ4. I would feel better with an 05+ though and that is going to probably remove the 4WD from the equation. Which reduces weight and reduces the power I need to make trap speed. But without good tires and a good launch, we know that a 121 mph trap speed is only good for very high 11s.

I care more about trap speed but at the same time, I don't want crappy traction when I am trying to use power - that is just annoying. On the other hand, a good firm Caprice launch and then roll into the throttle in 2nd would still present some very strong street performance.

http://www.yellowbullet.com/forum/showt ... p?t=599742

Wow, maybe the small rod LQ4 will handle it. I like this:

On my 2nd 2001 model lq4, turning 7200 on both. 1st one dies after 4 or 5 years, spun #1 rod bearing because I ran it too low on oil, not the engines fault, but several bottles through it at 150 jetting and never complained. The stock lq4 are supposedto hold 800 all day.

7200 rpm! It's rated for a tad over 5000 in stock form. Crazy.

If that's true, then a 750 crank hp combo gives me the 11.5 (on a hard 4WD launch) @ 117, more or less meeting my goal.

By the way, I don't really plan to become an active drag racer. These numbers allow me to communicate performance in a standardized way, since people know what 1/4 mile numbers mean. ET gives you launch capabilities (especially when taken relative to trap speed), and trap speed is very equivalent to power/weight ratio (but real power, not some made up number). Trap tells you what non-traction-limited acceleration will be like (i.e. a rolling race).

But this is all I really want.

https://m.youtube.com/watch?v=315FVwSc0Xk

Obviously Matt loves this. And how could you not? It is awesome. Roadmaster SS.