Is it safe to add a few pounds of boost without adjusting timing or anything? The tune I'm running is a bit smokey are WOT, and I'd like to try to clean it up if at all possible. Is it safe to push the stock LLY turbo to 35PSI?
Adding Boost
- Thread starter Cougar281
- Start date
you could add boost, but 35 psi is a ticking time bomb. i would not go that high. i max mine out wot 32. i rarely go that high. cruise on the highway it stays at 0.
It's not so much that you'll blow it up but it is just not effecient above 32 PSI - you are creating too much back pressure for the added boost to help you. You could go into Throttle base injection and pull some full out at high Throttle positions - or cut back pulse width in the lower right corner of your Main Injection Pulse tables. Just slowly pull some fuel out of the WOT areas until you clean it up.
We ran Blue at 45 PSI for quite awhile with no problems. It's still on the original 2004 turbo. I wouldn't worry about 36 PSI, the charger is alot bigger than an LB7 charger.
But I found on the dyno that 30-32 PSI boost makes the most power.
But I found on the dyno that 30-32 PSI boost makes the most power.
Dave,
Have you logged pulsewidth at WOT? My guess is that your low rail pressure condition is causing pulsewidth to skyrocket (in order to compensate), so fuel is being sprayed further down in the power stroke. When that happens, the truck soots..
Nick
Have you logged pulsewidth at WOT? My guess is that your low rail pressure condition is causing pulsewidth to skyrocket (in order to compensate), so fuel is being sprayed further down in the power stroke. When that happens, the truck soots..
Nick
Nick, at WOT it's 3350uS. I've found that over about 2000uS starts draining rail pressure. Whe nI have some time and a cool engine, I'm going to pull the race valve and see if it appears ok.
When I drain the rail the pulse doesn't increase. I run 3400 ms without smoke as well.
I guess all trucks are different.
Yeah, when you go to WOT on my truck (such as on the Dyno), the pulsewidth went to 3350 and stayed there the entire time it was at 100% TP, and while the rail pressure dropped off, built up, and dropped off again.
For those curious why I asked, it's because I'm often emailed tunes that lose rail pressure and don't recover because they have pulsewidth tables shaped like this. Notice the 90 and 100mm3 rows are single value for a while, before tapering up towards 5000. It's not uncommon for tunes to be built like this, and it's fine as long as the truck can hold commanded rail pressure. When it does not, the ECM compensates by opening the pulsewidth. I thought maybe Cougar281 was experiencing this. He isn't.
Anyway... the rows I described above are highlighted blue for those interested.
Nick
Anyway... the rows I described above are highlighted blue for those interested.
Nick
Increasing duration when the rail pressure is falling makes little to no difference.
It won't hold more pressure, if anything, the pressure will fall faster. If you wanted to "recover", you'd actually back off the duration so it ain't spraying fuel while the piston is halfway down the bore.
Everyone was playing with this before EFILive or HPTuners was out. We were using a Tech2 to watch the rail while we were stacking stuff. That's how we knew where to start when EFILive came out.
It won't hold more pressure, if anything, the pressure will fall faster. If you wanted to "recover", you'd actually back off the duration so it ain't spraying fuel while the piston is halfway down the bore.
Everyone was playing with this before EFILive or HPTuners was out. We were using a Tech2 to watch the rail while we were stacking stuff. That's how we knew where to start when EFILive came out.
Are you just posting that for everyone's information because I never saw anyone claim anything to the contrary. I think the reason tunes end up increasing duration as rail pressure drops is because the stock tuning does that.
I am so confused...sorry guys..I am running a PPE with the 225 tune and it smokes like train, I dont care about some smoke, but the excessive smoke is kinda bothering me. I would like to be ablt to hit it hard without leave the on ramp with a smoke screen.
The author was asking if he could run a Garrett LLY/LBZ/LMM charger at 35 PSI safely. I've seen lots of these chargers run at 40psi personally with no harm if the EGT's or nitrous didn't claim their life. Even at stock boost, EGT's or nitrous can kill, so it's not the 35psi that is the threat.
In the replies was a claim that a tuning mistake that some tuners make causes the duration to rise at WOT when the rail falls. I've seen the exact opposite. Most my friends would agree. Nothing more, nothing less.
Stock tuning normally won't drain the rails unless something is bad.
As an outside observer, here's what I saw.
Cougar 281 made a post saying that he wanted to clear up some smoke he was having and asked if it was safe to bump boost up to 35 psi
You then stated you felt it was safe to run that boost level, but the turbo was most efficient at 32.
Nick then asked if Dave had logged pulse during the rail pressure drop he had experienced to see if the pulse was increasing as rail dropped. He stated that if this was the case it could result in an increase in smoke.
You then stated you had never seen pulse increase when rail pressure dropped.
Dave then stated he never saw an increase in pulse when rail pressure dropped.
Nick then said he wanted to make sure the pulse table wasn't setup to cause a problem, but it was apparent that it wasn't so that variable was eliminated.
Nick then posted an explanation on why he thought the pulse table might be causing a smoke problem with a screenshot of a tune that could exhibit the problem he had pointed out as a possibility.
You then said that tuning to increase pulse as rail pressure dropped did not help to increase rail pressure, but instead would cause rail pressure to drop more.
I then said that I didn't really see how that was relevant to the discussion as no one had made any claims to the contrary, and stated that that type of tuning is likely a result of the stock pulse table having those characteristics.
Are you saying that tuning mistakes like Nick posted would not cause pulse to increase in the event that the rail pressure drops significantly?
I never claimed stock tuning would drop rail pressure either, but stock tuning does call for pulse time to increase as rail pressure drops. I believe the reason for this is because the stock pulse map is calibrated to give the correct quantity of fuel regardless of rail pressure. Like you said, stock tunes won't drain the rail so they would never run in the low rail pressure areas at higher fuel quantities, but the table is still shaped that way. I would imagine that most people, as I have done, enter their max pulse time at the max fuel pressure column and then copy it across until it intersects with the stock fuel table. That is most likely why tables end up with an increase in pulse time when pressures get too low.
Man, this thread got way off topic...
I myself have run that high for a long time. Heck the turbo has lasted longer than anything else on the truck:rofl:
watch your EGTS and when you get into that area that area of hgher boost...Do they drop or stay the same if they drop then i would keep it that high JMHO
also a drive pressure gauge is nice when playing with VVT helps with adjusting vane posistion to make the turbo react better
If your truck is draining rail.... dont tune it out, pimp it out
watch your EGTS and when you get into that area that area of hgher boost...Do they drop or stay the same if they drop then i would keep it that high JMHO
also a drive pressure gauge is nice when playing with VVT helps with adjusting vane posistion to make the turbo react better
If your truck is draining rail.... dont tune it out, pimp it out
That's pretty much the same thing as me. Some smoke is fine, but to blanket an entire on ramp with a thick cloud of smoke is not what I want to do... In theory, upping the boost a bit could help move more air and maybe clear it up a little.