HTT or Cheetah?

[Brayden]

Also I have rewatched the video of the 11.55 run. Why does the truck backfire 3/4 the way down the track. I have been building/racing Duramax trucks for about 8 years, the only time I have seen a duramax do that is usually nitrous or some other fuel being sprayed in.

To reply to the highlighed part. I have done something very similar to what you see in that vid. Big injectors, low timing, 2 pumps, and that can happen on the shift.

I think I have described the setup on the truck numerous times.. Johnboy is reaffirming my setup exactly.. Big Sticks, low'ish timing 26 degrees or so, dual pumps 29,xxx psi of pressure and dual pumps....

If you want I can dumb it down for you but... 4-5 shift drops about a 1000 rpm, and by doing that the lookup cell in the timing table jumps about -18 degrees. So we end up at 8 degrees of advance after the shift and what that means is there is fuel that ends up unburnt in the exhaust manifold, turbo, stack etc...

That's a timing backfire. It happens when you are trying to make big hp on a stock motor... which is something you can't do with timing for very long which I'm sure you guys have found out.

Brayden

 

[McRat]

Sure thing. I've made 798rwhp uncorrected at 4400rpm with lots of timing. Probably = 830rwhp corrected. No bark. At no time going down the track am I running 26 deg of timing.

Perhaps you could dumb it down a bunch more for me.

 

[Brayden]

Sure thing. I've made 798rwhp uncorrected at 4400rwhp with lots of timing. Probably = 830rwhp corrected. No bark. At no time going down the track am I running 26 deg of timing.

Perhaps you could dumb it down a bunch more for me.

@ 4400rwhp? Do you mean uS?

So you're saying the timing is higher than 26 degrees or lower?

I'm telling Dan that the timing went from 26 degrees to 8 degrees BTDC.

 

[Brayden]

www.fleeceperformance.com/Media/Brayden_TimeSlips.jpg

www.fleeceperformance.com/Media/JNeals_Truck_Weight.jpg

www.fleeceperformance.com/Media/Jerrod_Dyno_730hp.jpg

Now before the dyno analysts get all antsy... the blue spike is where the tach pickup lost signal. It made 730 before it lost it. The subsequent 2 runs were losing power from heat soak. The ramp in the graph is when the dual pump controller goes to 0% duty cycle... I did this to soften the cylinder pressure down low to keep the motor alive, and then turn it on later in the curve.

Brayden

 

[Turbotug]

@ 4400rwhp? Do you mean uS?

So you're saying the timing is higher than 26 degrees or lower?

I'm telling Dan that the timing went from 26 degrees to 8 degrees BTDC.

Probably 4400prm.

 

[McRat]

Thanks for the correction.

 

[Brayden]

So I'd say that you haven't experienced timing backfire because you have plenty of advance for the rpm and power you desire to produce on fairly stock? or stock size injectors.

We use big injectors and less timing and we experience it. That's all I'm saying. Seems black and white to me.

Brayden

 

[McRat]

www.fleeceperformance.com/Media/Brayden_TimeSlips.jpg

www.fleeceperformance.com/Media/JNeals_Truck_Weight.jpg

www.fleeceperformance.com/Media/Jerrod_Dyno_730hp.jpg

Now before the dyno analysts get all antsy... the blue spike is where the tach pickup lost signal. It made 730 before it lost it. The subsequent 2 runs were losing power from heat soak. The ramp in the graph is when the dual pump controller goes to 0% duty cycle... I did this to soften the cylinder pressure down low to keep the motor alive, and then turn it on later in the curve.

Brayden

I'm not siding with PPE here, and I'm not sure PPE belongs in this thread, since it's a High Tech vs. Fleece Performance thread.

Congrats on the numbers, and I'm sure if you say you didn't spray it, you didn't. The jump in the dyno is not nitrous, but I can't tell what it is.

Guess we will wait until other dragracers replicate the setup with the same listed mods.

I'll admit I'm puzzled why you'd add 300lb to truck to race it, but to each their own. A deluxe 4x4 EC/SB weighs 6420lb as delivered including spare tire and 1/2 a tank and window sticker. An RC 4x4 is normally 61xx when delivered, much of the difference is the weight of the back seat.

 

[McRat]

So I'd say that you haven't experienced timing backfire because you have plenty of advance for the rpm and power you desire to produce on fairly stock? or stock size injectors.

We use big injectors and less timing and we experience it. That's all I'm saying. Seems black and white to me.

Brayden

So far, I've only got bursting from too much timing, never too little. I haven't seen turbo bark yet at the dragstrip except with stock chargers and misbehaved harness boxes.

 

[beach_33]

they didnt add weight. that is the way the truck sits ever day. it is a sled puller not a drag racer. they didnt want to remove to much weight from as they wanted to see what it would run the way the truck is set up everysingle day. just to try and shut everyone up. i think the extra weight comes from the toolbox, fifth wheel hitch, and custome sled pulling hitch. plus lets not forget that brayden is not a small fellow by anyones standards

 

[jneal]

Remember Pat, The truck had all of it's pulling accessories on it except the front bracket when it was raced. So 300 pounds of accesories isn't hard to add up to. Full set of u-joint shields, bump stops, pulling hitch, tool box, and 20 inch wheels. That alone should about add up to 300lbs. We asked the when were gonna race it, "Shouuld we strip the truck". The unanamious answer was NO. so we didn't strip it down out of it's pulling setup simple as that.

And the jump in the dyno rn was when we shut off the 2nd cp3 since we didn't have a duel fuler controller that would work. We just had a switch that kept 12vdc to the 2nd pump and then we'd turn the power off the the 2nd pump dring the run causing an abrupt jump in rail pressure. Hence the jump in the dyno graph.

 

[McRat]

Remember Pat, The truck had all of it's pulling accessories on it except the front bracket when it was raced. So 300 pounds of accesories isn't hard to add up to. Full set of u-joint shields, bump stops, pulling hitch, tool box, and 20 inch wheels. That alone should about add up to 300lbs. We asked the when were gonna race it, "Shouuld we strip the truck". The unanamious answer was NO. so we didn't strip it down out of it's pulling setup simple as that.

And the jump in the dyno rn was when we shut off the 2nd cp3 since we didn't have a duel fuler controller that would work. We just had a switch that kept 12vdc to the 2nd pump and then we'd turn the power off the the 2nd pump dring the run causing an abrupt jump in rail pressure. Hence the jump in the dyno graph.

Not sure about that. Two pulls have the jump the other doesn't. That's why I'm convinced it's not nitrous. A nitrous jump looks like that, but the third curve is OK.

 

[jneal]

I'd also like to make a point to notice the fact that I have now made several posts in this thread directed toward people of doubt, AND I HAVEN'T FLEW OFF THE HANDLE and have kept my composure. My anger management classes are working.:hug:

 

[jneal]

Not sure about that. Two pulls have the jump the other doesn't. That's why I'm convinced it's not nitrous. A nitrous jump looks like that, but the third curve is OK.

The 3rd run we flipped the switch alot earlier than the previous 2 runs in an attempt to get torque numbers up. Needless to say it didn't work as well as we'd have liked. but that is why the jump is not as abrupt. Rail pressure hadn't dropped yet before we flipped the switch. the previous 2 runs by the time Brayden seen pressure dropping on the data log and told Mark to flip the switch it was to late, pressure had already dropped quite a bit and then when he flipped the switch it caused a spike due to rail pressure going straight to 29,XXX psi. On the 3rd run he just flipped the switch right after the he hit the button for the dyno to start the run.

 

[Brayden]

they didnt add weight. that is the way the truck sits ever day. it is a sled puller not a drag racer. they didnt want to remove to much weight from as they wanted to see what it would run the way the truck is set up everysingle day. just to try and shut everyone up. i think the extra weight comes from the toolbox, fifth wheel hitch, and custome sled pulling hitch. plus lets not forget that brayden is not a small fellow by anyones standards

I'm 250lbs of the extra weight...

 

[Brayden]

Not sure about that. Two pulls have the jump the other doesn't. That's why I'm convinced it's not nitrous. A nitrous jump looks like that, but the third curve is OK.

third run the switch is turned on earlier.... I told Mark that he could turn the pump on earlier to try to make some more torque.. It smoothed out the curve because rail pressure never had a chance to drop then spike, it just stayed consistent @ 26kpsi +

Brayden

 

[McRat]

third run the switch is turned on earlier.... I told Mark that he could turn the pump on earlier to try to make some more torque.. It smoothed out the curve because rail pressure never had a chance to drop then spike, it just stayed consistent @ 26kpsi +

Brayden

Nope. Look at the graph. The output is the same before the bump. It's something else.

 

[Brayden]

More explanation? I'm not following....

If you could average the red and blue lines together pre spike and post spike they'd average about the same as the green line.. which again is dropping because of the heat soak on a 90 degree Indiana day.

 

[Josh2002cc]

I'm with Jneal

I'd also like to make a point to notice the fact that I have now made several posts in this thread directed toward people of doubt, AND I HAVEN'T FLEW OFF THE HANDLE and have kept my composure. My anger management classes are working.:hug:

Hey....me tooo

Can't say the same for mr. beech, but that is okay doctor says to take 3 breaths then react. :hello:

 

[McRat]

All three pulls are within a normal window, both before and after the "event".

Flipping the switch during the event didn't change the engine output before it was flipped.