What RPM does your primary make boost?

T

TXUMSC

New member
My 475 isn’t registering any boost on its gauge until about 2250 rpm. Between there and 3k I can get 14 psi out of it making about 44-45 overall. EGT’s are not hot (950-1150) and drive pressure is 1:1 pretty steady. Should I just shut up and drive or is something off? Is this typical when unloaded?

S362/68/12 over S475/87/1.10, custom tunes, BBI 0.5’s

Spring gate is six turns in from initial tension and should have the gate opening at 15-17 psi. Any tighter than that and I notice EGT’s getting over 1250 pretty easy.

All I’ve run is my 120 HP tune so far.

Boost leak kit arriving any day.
 
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Sounds like you need to throw a hotter tune on it.

I would think that set of compounds making decent power would be pushing them to around 65 psi.
 
So the 475 isn't making any boost at all until 2200,
How long is the hotpipe setup on this?

Is it one where the primary is upfront on top with a long hotpipe?
 
Somethings off, my vp truck with 62/475 makes 70 psi. That's with a 475/96/1.10. You should be able to push that setup a whole hell of a lot harder than me. I would think you'd hear a boost leak that large. If you go tighter on your waste gate it may climb initiallly but then drop quite a bit once it cleans the fuel up. 1250 is nothing to worry about I don't think
 
jasonc said:
So the 475 isn't making any boost at all until 2200,
How long is the hotpipe setup on this?

Is it one where the primary is upfront on top with a long hotpipe?
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Gauge doesn’t move at all until 2250 but I can hear the turbo.

It’s a Crazy Carl’s kit. The hot pipe isn’t long.
 
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thatguy69 said:
Somethings off, my vp truck with 62/475 makes 70 psi. That's with a 475/96/1.10. You should be able to push that setup a whole hell of a lot harder than me. I would think you'd hear a boost leak that large. If you go tighter on your waste gate it may climb initiallly but then drop quite a bit once it cleans the fuel up. 1250 is nothing to worry about I don't think
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Once I get the boost leak test done then I’ll know what I need to do next. I do hear a whistle but to me it’s just the turbo.
 
You are leaking boost someplace. Probably what you're hearing when you think you're hearing charger.
 
Carl has been very helpful to this point. I didn’t ask him on this as I wasn’t sure what I should expect from this setup, my first time in a compound truck ever.
 
Honestly, I don't think there's anything wrong. Those egt's sound reasonable for the lack of fuel that you're throwing at it. Your small charger could keep up with what you're commanding right now by itself.
 
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Phooker said:
Honestly, I don't think there's anything wrong. Those egt's sound reasonable for the lack of fuel that you're throwing at it. Your small charger could keep up with what you're commanding right now by itself.
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I agree those temps are reasonable and if they remain that way then I’ll be happy. Not looking to make any crazy HP goals, simply tow without EGT’s getting too high. My small charger got hot when towing heavy. I don’t push past 1250 deg and it was nothing to see that towing our 5th wheel (15.5k unloaded) up most any hill in 3rd gear locked.

My main concern here was, by comparison of others experiences, my primary doesn’t seem to be doing much. I want to ensure I’m getting all I can from this costly modification.
 
TXUMSC said:
I agree those temps are reasonable and if they remain that way then I’ll be happy. Not looking to make any crazy HP goals, simply tow without EGT’s getting too high. My small charger got hot when towing heavy. I don’t push past 1250 deg and it was nothing to see that towing our 5th wheel (15.5k unloaded) up most any hill in 3rd gear locked.

My main concern here was, by comparison of others experiences, my primary doesn’t seem to be doing much. I want to ensure I’m getting all I can from this costly modification.
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Stock pump/60%S&S on my old ats compound setup made roughly 45-50lbs on max effort file. Absolutely no smoke at all and maybe 1200 degrees. Towing my halfton at 80-90 (roughly 10k lbs between truck and trailer) netted 1000-1100 degrees flat ground. If you're truly worried, I'd hook it to the camper and make a quick run and see.
 
Phooker said:
Stock pump/60%S&S on my old ats compound setup made roughly 45-50lbs on max effort file. Absolutely no smoke at all and maybe 1200 degrees. Towing my halfton at 80-90 (roughly 10k lbs between truck and trailer) netted 1000-1100 degrees flat ground. If you're truly worried, I'd hook it to the camper and make a quick run and see.
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That’s good information I can use, thank you. Probably won’t be until October before I can get the trailer connected, but that will be the true test.
 
TXUMSC said:
That’s good information I can use, thank you. Probably won’t be until October before I can get the trailer connected, but that will be the true test.
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I honestly don't think you're making enough heat to actually put the low pressure charger to work yet. Doing a boost leak test won't hurt though.
 
Boost was leaking behind the S300 compressor housing, the boost elbow plug, passenger side boot to the intercooler and top of boot to the intake horn. All is tight, no more bubbles. Pressure leaks down pretty rapidly while testing but I assume without plugging the system it leaks out the valves. I was able to get it up to 20 psi at a time and spray and tighten until I found no more issues.
 
Not yet, in the morning I’ll get a chance.

What I did gather is that my intermediate boost gauge is reading a solid 4 psi low. Doesn’t sound like much but if I’m only registering 14 at full tilt and it should be 18 then my calculations will change.
 
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Truck seems to feel much better. I tightened everything up and double checked the whole system. Gave it a little hit today and saw 48 psi overall, 1116 deg EGT, primary came on a bit quicker and all at 2800 rpm instead of over 3k with PLENTY of pedal left. If my boost gauge is in fact off by 4 then I was at 17 psi on the primary and about 14 on the secondary. Drive/boost is still very close 1:1 the whole time.
 
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