TrickrTreat

iTrader: (3)

02camaross +1 , its Probably the compressor. If you plot it out on a compressor map i bet you'll find that in the lower boost levels where your not moving much air horsepower wise, your under its range of efficiency (not enough pressure) , and then by the time you crank the pressure up, your moving so much more air , that your "outrunning" it. Basically you need a bigger compressor.

I mean what you got will get you down the track and put down good numbers , but i bet its whats causing your "issue"

dville_gt

iTrader: (5)

I just keep hearing that there is no way I could be running out of turbo, that is what this seems like to me.

bad6as

iTrader: (17)

I think you need to start mesuring back pressure in the hot side. If you set the boost leash to 20 psi co2 that's what it puts out. As you get higer up in rpm and you flow more air into the turbo you create more back psi. I belive the 1.32 ar and 96mm wheel flows around 57lbs. My 87mm t4 1.25 flowed a lil bit less and at 14 lbs boost I had 11psi back pressure.

bad6as

iTrader: (17)

At 3300lbs at 17psi I traped like 151. At 25 psi I traped the same.

dville_gt

iTrader: (5)

Now this is an interesting thought. I just always assumed that with the 1.32 ar T6 housing I'd never face a back pressure issue. If this is the case I wonder if moving to a larger comp wheel would do anything for me.

skinnies

iTrader: (33)

Interesting if its a back pressure issue why I wouldn't have the same problem, 7675 .96 25+ lbs, it has to have a decent chunk of back pressure, but we've never seen any boost drop issues like you are having. I have 3lb spring and run 27bs on top of the gate with onboard air.

dville_gt

iTrader: (5)

ya, my buddy who is a well known turbo guy around here just also told me to put a heavier spring in it and more c02. I just don't want to go above the 22psi peak I am currently seeing, I just want it to stay at 22 vs. falling off.

dschmittie1

iTrader: (64)

How does your boost controller control boost my just appling a set pressure to the waste gate to achieve target boost or is it like an AMS1000 that measure manifold pressure and applies the needed pressure to the gate to hit target boost?

A back pressure issue would surface like you have having with an AMS 500 or the like that just applies a certian pressure to the wastegate

skinnies

iTrader: (33)

You can try a heavier spring and not have to go over 22, just put in a 10lb spring, should still be able to control the launch fine, and run less co2.

dville_gt

iTrader: (5)

ya, it is just a time based co2 controller (boost leash). so once i ramp in the pressure it holds a consistent pressure on the top of the gate.

but would this provide any benefit over a lighter spring and more co2? the co2 acts to assist the spring, so if 5lb spring + 20 psi is exerting a certain amount of pressure against the gate then a 10lb spring + whatever psi would still make 22psi and fall off through the run.

The only way I can see is to just throw the extra co2 at it and deal with the peak probably being 25psi then tapering off to 20psi by the end of the run.

I think it is too risky to try to set up the co2 curve to attempt to flatten the boost curve by gradually increasing pressure throughout first, then (based solely on time), try to drop the pressure on the gate then gradually increase it again through high gear. If I pedal, get out of the groove, whatever it would totally throw off the timing.

Is there any way to know for certain if it's back pressure or simply lack of compressor flow?

bad6as

iTrader: (17)

Mesure boost at the compressor wheel and also the intake manifold. Intercooler could be causing a big pressure drop

onfire

iTrader: (17)

Where do you reference the gates? Manifold or comp housing?

dville_gt

iTrader: (5)

Manifold, would this make a difference?

71 chevy

iTrader: (18)

probably because your intercooler is very inefficient and your 20 psi at the intake could be 30 psi at the turbo and out of its efficiency range

Old Geezer

iTrader: (3)

What 71 said.^^^^^^^^^^^

dville_gt

iTrader: (5)

i'm sure my intercooler sucks, it's a Godspeed (whatever that is) 31x12x4, 3" in and out. Any reasonably priced (similar sized) options?

Sales@Tick

iTrader: (3)

A larger compressor if you're running into back pressure issues wouldn't help the situation since you wouldn't have enough turbine to support more compressor.

I don't think you have an excessive drive pressure issue, but I bet it's at least 2:1. Single turbo's inevitably will have more drive pressure than a twin set-up, it's just the nature of the beast.

What I would do, is just try more gate pressure and where the boost rises higher than you'd really like to target, yank a degree or two of timing out of it in those regions.

dville_gt

iTrader: (5)

I'm just trying to figure out how to get this thing in the 5.6x's without throwing much money at it. I bought an additional 14gph meth nozzle to add to my existing single 14gph nozzle then I was thinking about possibly bumping up the timing a little and trying to increase the co2 such that it will maintain ~20psi throughout the run (which probably means a peak pressure somewhere around 25+ psi), you think pulling a degree or two will allow it to live at that pressure? I've been .74 twice now and I cut a new best 60' last time out of 1.30 (had to abort that run as I hit coolant 100ft out). I don't think it'll take too much to get it where I want to be, but who knows.

overhere

iTrader: (2)

take a pressure reading at the compressor and see where that is at compared to manifold.

HRHohio

Can you plot your IAT with the graph? What are your IATs?

Perhaps your heatsoaking your IC. Hotter air = less dense = lower pressure values (harder to compress/volume).

Just a thought.