I cant figure it out, I ran a 12.40 on mt streets with a jl chip and 50 shot dry system, stock pulleys and filter. The other day I added an lfp upper pulley and a JL 5lb lower with the 50 shot and only ran a 12.20 at 111mph. It seems the more you do to these trucks the more it takes to make them quicker. Is anyone else having this problem or what gives?

 

I think with our trucks you can gain a lot at first with just a few mods, and then the faster you get the more it takes to gain a little more! I think for the mods you have you are running pretty darn good!

 

It might have something to do with Aerodynamics ?

The faster you go, the more Aerodynamic drag is created therefore requirring greater amounts of power to over come it. Look at your truck, now look at a Vette or Viper or whatever, what do you think will have the most drag?

Just my $.02

 

the first few seconds cost a few hundred, the last few tenths cost a few thousand. thats been a problem for some time now

 

What were the weather conditions? specifically Barometer and humidity? Those 2 things will make or break your track times. Sometimes you have to look below the surface.

 

The law of diminishing returns.

The quicker you get, the harder it is to make big gains. I guess I may be too conservative for this group, but I like to make one change at a time, and flog it to death, until it just won't improve any more. That way you get your money's worth out of your mods.

My .02

 

Compare 60 foot times, weather, & track conditions. All that comes into play bigtime!!!!

 

If you have the stock exhaust system(?) still on, you may be 'choking' off all that extra 'air' being compressed. I think mine is suffering from that situation but I d/k for sure.

Dan

 

So, what you're telling us is that you ADDED an upper AND lower pulley, but did nothing to your chip (fuel&timing adjustments etc.) to compensate for all the added boost? Your truck is now pushing at least an extra 6 psi(upper and lower pullies) of boost. If it were me, I'd be callin JL and inquiring about a reburn before you do some damage to that motor by leaning it out too much.
That *may* have something to do w/ your ET's. Maybe not. I would think JL might have some ideas.

 

BINGO!!

You're at the point where long tube headers will make a huge difference. You have to work on that air-flow from both ends. I've only got an extra 5-6#s of boost and don't see any point in going any further without a set for myself.

If you haven't reburned your chip, that will make a difference, also.

 

Hey,

I think its time for Long Tube headers..Our local track isn't the greatest, it goes uphill close to the end of the 1/4 mile, Plus there was a cold front moving in the area. It's usually pretty high humidity in GA.

Hey Odin's Wrath, can you replace that Porsche 911 with a Lightning?

Dan, He has the full Bassani exhaust with the shorty headers and X-Pipe.

 

Just as BBQ said the first few seconds are easy. You have to realize that the required MPH greatly increase per sec the further down you go. D= V*T is an equation that everyone knows. but since D is a constant inorder to isolate T (what we all are looking at) the equation D/ V = T or D/ T= V. I wish that I could draw on this board but in the first eqation the value V must increse exponentially to change T. Since acceleration is the derivative (change per given unit ie second) in velosity the value a=d(v) or .5(v)^2 (notice the squared function). In the second the same applies but inversely. Now for a few numbers for yall to tickle your fancy...
(these numbers come souly from the equations above)

if a car (truck) got a 20second Et... (1=1 mph/mile) : Distance/ Time = Velosity so....
1/4mile = 1320ft.... 1320/20sec = 66mph.... now that's bad but if we move it to only 1 second faster the velosity changes from 66 to 66.47 only a .5mph change now lets move that WAY down... from say 15 down to 14 sec.... 15 seconds = 88mph and 14sec = 94.3 mph now that's a 6.3 mph change... doesn't sound like alot but we all know what even 1mph can do. These mph seem slow because of the acceleration curve that any multi geared car. It's concave down (accelerating at a decreasing rate). But now for the extreme. the fastest L so far is 11.2 @ about 118. now the difference between the 20sec car @ 66 and 11.2 @ 118 and a 10sec flat @132mph.... now if i change the te by .2sec the mph goes up to 134.5 at that it's 2/10= 2.5mph.... Hope that helps a little

 

Does JL know it's a "dry" shot (higher injector duty cyle needed)as opposed to a "wet" shot (no increase in injector duty cycle, just timing)? Need to make some runs and check the plugs... the ones that are easy to get to.

 

Spade$.........Being an engineer I had to take more than my fare share of math and unfortunately I understood everything you said

Merry Christmas........Joe

 

It has everything to do with Aerodynamics. You are right on the money!