back pressure desired

sonic blue l

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Just checking to see if my thinking is correct.

If you want more boost increase the desired back pressure?

Now with that said, high back pressure is restriction. So im just curious as when I compare the hd300 to the easy tune, the desired back pressure is lower on the easy vs the hd300 in multiple areas and in fact I don't see any area where the hd300 is higher.

Anyway I have a 72 atmo and was debating about playing with the desired back pressure tables, so just looking for suggestions/ information on the topic of back pressure. Or even any changes that one would consider after adding a 72 atmo vs the stock one. Oh, I also have a colt cam, and ih maxxforce pistons (not cut, not coated), wondering if that would warrant changes to timing, etc.

Thanks.
 
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sootie

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No changes to tuning required for atmo turbo swaps
 

ckrueg

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Yes the way to get more boost is to increase desired EBP up to a point-more exhaust pressure means increased turbine/compressor speed. When the tune commands higher EBP, the vanes close to increase it, and when the desired EBP is lower, the vanes open to decrease it. The limit is at high load and rpm, EBP will keep rising even when the vanes are wide open, and at low rpm, the vanes can be closed all the way and there is just not enough airflow to increase EBP.
 
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Just checking to see if my thinking is correct.

If you want more boost increase the desired back pressure?

Now with that said, high back pressure is restriction. So im just curious as when I compare the hd300 to the easy tune, the desired back pressure is lower on the easy vs the hd300 in multiple areas and in fact I don't see any area where the hd300 is higher.

Anyway I have a 72 atmo and was debating about playing with the desired back pressure tables, so just looking for suggestions/ information on the topic of back pressure. Or even any changes that one would consider after adding a 72 atmo vs the stock one. Oh, I also have a colt cam, and ih maxxforce pistons (not cut, not coated), wondering if that would warrant changes to timing, etc.

Thanks.


I'm with you on the sluggish feeling. I just finished my own overhaul: HD pistons, RCD cam. On the boost, it feels strong. Off the boost, it doesn't have the same nuts as before. I even had the injectors tested and balanced at RCD.

I'm going to see if i can find some time to go visit someone who can live tune it.
 

sonic blue l

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Yes the way to get more boost is to increase desired EBP up to a point-more exhaust pressure means increased turbine/compressor speed. When the tune commands higher EBP, the vanes close to increase it, and when the desired EBP is lower, the vanes open to decrease it. The limit is at high load and rpm, EBP will keep rising even when the vanes are wide open, and at low rpm, the vanes can be closed all the way and there is just not enough airflow to increase EBP.

Cool, thanks
 

sonic blue l

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I'm with you on the sluggish feeling. I just finished my own overhaul: HD pistons, RCD cam. On the boost, it feels strong. Off the boost, it doesn't have the same nuts as before. I even had the injectors tested and balanced at RCD.

I'm going to see if i can find some time to go visit someone who can live tune it.

Mine does not feel sluggish, I just wanted to see why hd300 has minimal changes to boost vs the mild. So Im taking it that the fuel is driving the turbo harder, so I still think some fine tuning should be beneficial.

I wonder how much different your cam is vs my colt. Also do you have cut pistons? My truck is pretty responsive and I tow my 5th wheel no problem.

Live tuning would be nice, I had tsd tunes on my 6l but only way to get them on my 6.4 is live tune. A bit too far of a drive for me :(
 
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As I said, the truck pulls great on boost. Towing is not a problem. It just doesn't have the Same off boost response as before.

The pistons are not cut. The cam is an RCD stage 2.

Sorry if I mucked up your thread, I was searching for some info when I came across this and I must've read in between the lines.


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sonic blue l

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As I said, the truck pulls great on boost. Towing is not a problem. It just doesn't have the Same off boost response as before.

The pistons are not cut. The cam is an RCD stage 2.

Sorry if I mucked up your thread, I was searching for some info when I came across this and I must've read in between the lines.


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No problem. This sounds like the same issue your having.
http://powerstrokearmy.com/forums/showthread.php?t=35310
 

purplepstroke

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I build most my engines with the Ih pistons and have pretty much concluded the ih pistons make a more sluggish take off. I have had other people agree with me too.
 
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